Does ex vivo labelling of proliferating cells in colonic and vaginal mucosa reflect the S-phase fraction in vivo? The ex vivo labelling of DNA-synthesizing epithelial cells in colonic and vaginal mucosa was compared with in vivo labelling. For this purpose, in vivo S-phase cells were labelled with [3H]thymidine (Tdr) and ex vivo labelling was continued by culturing tissue specimens in bromodeoxyuridine (BrdU). Various methods of tissue culture were employed in order to improve diffusion of medium (and BrdU) in the tissue. BrdU and 3H-TdR labelling were evaluated by immunohistochemistry and autoradiography respectively. Ex vivo labelling resulted in a patchy distribution of labelled cells, which did not correspond with the 3H-TdR labelling pattern obtained in vivo. Under the described conditions ex vivo labelling does not appear to be a reliable for estimation of the proliferative activities in vivo.


Vimentin antibodies stain membranous epithelial cells in the rabbit bronchus-associated lymphoid tissue (BALT). The lymphoepithelium covering the bronchus-associated lymphoid tissue (BALT) of the rabbit lung was studied with monoclonal antibodies against vimentin, using the indirect immunoperoxidase technique. In the lymphoepithelium single cells which had a membranous apical cytoplasm and engulfed intraepithelial lymphocytes were vimentin-immunoreactive. All other epithelial cells of the lymphoepithelium and of the surrounding airway epithelium did not bind vimentin antibodies. The results support the hypothesis that the membranous epithelial cells in the lymphoepithelium of rabbit BALT are analogous with intestinal M-cells, which in rabbit Peyer's patches and appendix are selectively labelled by vimentin antibodies.


Transplantation in the treatment of paralysis agitans (Parkinson's disease). Over the past 3 years, there has been great interest in transplantation therapy in the treatment of Parkinson's disease. Following the impressive results reported by Madrazo in the spring of 1987, more than 350 cases of adrenal medullary implantation have been performed worldwide. There has been a significant reduction in "off" time and an increase in "on" time without chorea in 40% of patients having this procedure. The duration of effect is 1 year in half of these cases, with the other half (20% of all patients) still demonstrating significant improvement 3 years after the procedure. The mechanism of the bilateral beneficial improvement is unknown. The survival of adrenal medullary tissue has not been demonstrated at autopsy. It is thought that the mechanism of improvement involves either regenerative sprouting of the remaining dopamine producing neurons as a consequence of the release of neurotrophic factors or an interruption of the striatal pallidal output inhibitory influence of the basal ganglia on the thalamus (or both). Fetal mesencephalic implantation has also been attempted in more than 100 cases worldwide. The improvements when seen are not any more dramatic than those following the best results of adrenal medullary implantation. Graft survival has not been proved; it remains a possibility that interruption of the putamino-subthalamic pallidal pathway or a trophic influence of the tissue provides an alleviation in parkinsonism. The ethical controversy, need for long-term immunosuppression, and difficulty with obtaining tissue of the appropriate age and delivering the appropriate quantity to the putamen have made this technique less than adequate.(ABSTRACT TRUNCATED AT 250 WORDS)


Managing a patient with progressive HIV disease. This monthly series was developed from the AOA Task Force on AIDS Writers' Workshop, held August 16 to 18, 1991, in New York. The workshop was sponsored by an education grant from Burroughs Wellcome. It will provide brief clinical updates and perspectives on the human immunodeficiency virus (HIV). Readers may request tear sheets from the AOA editorial offices.


Voices From the Future: what students, interns, and residents want from osteopathic graduate medical training. The need to attract students to--and keep them in--osteopathic internship and residency programs is great. Recognizing this fact, the osteopathic hospitals, through the American Osteopathic Hospital Association, have placed a renewed focus on liaisons with osteopathic medical education. Voices From the Future represents one such effort. This report reveals how osteopathic medical students, interns, and residents perceive the current state of osteopathic graduate medical education programs as well as the changes that they would like to see incorporated.


Guillain-Barré syndrome, pregnancy, and plasmapheresis. The case of Guillain-Barré syndrome (acute inflammatory polyradiculoneuritis) in pregnancy reported here brings the total reported number to 35. The patient had plasmapheresis with no maternal or fetal complications. She did not require mechanical ventilation. This is only the fifth reported case of Guillain-Barré syndrome in the gravid patient involving plasmapheresis. There have been no controlled studies assessing the safety of plasmapheresis in the pregnant patient with the disorder. The possible risks of the procedure need to be weighed against the high maternal mortality rate in such a patient.


Relationship between CNV asymmetries and individual differences in cognitive performance, personality and gender. This study used verbal and spatial variants of a cognitive 'match/mismatch' paradigm to explore relationships between functional brain asymmetries and individual differences in cognitive performance, personality and gender. Contingent negative variation (CNV) elicited in the 'match/mismatch' paradigm was recorded from central (Cz, C3 and C4) derivations in two male and one female samples. Results indicated gender differences in both the degree and direction of CNV asymmetries. Males showed a left hemisphere asymmetry in the verbal task and a right hemisphere asymmetry in the spatial task, with significant laterality (C3-C4) differences between tasks across the foreperiod. Females showed a left hemisphere asymmetry in both tasks with laterality differences between tasks confined to the early part of the foreperiod. CNV amplitude in the verbal task correlated with verbal memory performance and verbal I.Q. CNV amplitude in the spatial task correlated with visuospatial memory performance. Social extraversion was associated with greater left-hemisphere asymmetry in both tasks, while behavioural extraversion was associated with left-hemisphere asymmetry in the verbal task only, and with smaller verbal than spatial CNVs.


Bilateral electrodermal activity: reliability, laterality and individual differences. A first aim of the present study was to estimate the short- and long-term stability of individual response patterns in bilateral electrodermal activity (EDA). A second aim was to examine the relationship of individual brain laterality to both peak amplitude and peak time based electrodermal asymmetry. Additionally, subjects were presented with verbal and spatial tasks to estimate the balance of left/right asymmetry in cerebral activation at time of testing. Finally, the influence of smoking, coffee consumption and subjective circadian phase (morningness/eveningness, subjects' rise time) on bilateral asymmetry and EDA lability was examined. Results indicated moderate to high short-term reliabilities of EDA laterality coefficients, but insufficient long-term stability. Handedness and conjugate lateral eye movements (CLEMs) were not related to asymmetry of EDA, but a significant interaction between CLEM tendency and smoking/nonsmoking on laterality of both EDA parameters was observed. Amount of coffee consumption was also significantly related to electrodermal asymmetry. Analysis of performance data demonstrated that intraindividual shifts of EDA laterality from one recording session to a following one were associated with corresponding shifts in accuracy of verbal/spatial performance. Degree of subjects' electrodermal lability differentiated significantly between speed and accuracy of performance in both verbal and spatial tasks, and was substantially related to subjects' rise time.


The effect of participation in an exercise training program on cardiovascular reactivity in sedentary middle-aged males. Exaggerated cardiovascular reactivity to mental stressors may be a risk factor for cardiovascular disease. To determine if participation in a moderate intensity aerobic exercise training program reduces cardiovascular reactivity to laboratory stressors, 40 sedentary middle-aged males were randomly assigned: training group (n = 25) and control group (n = 15). Cardiovascular reactivity during and after three mental stressors (passive responding, push-button Stroop and verbal Stroop) and mild exercise (bicycle ergometer) was assessed before and after an 8-week intervention. VO2(peak) was determined using the Balke protocol. Among 19 subjects who completed the training, VO2(peak) increased 13.7%. Also, trained compared to untrained subjects showed significant reductions in baseline and absolute heart rate responses to all stressors. Baseline adjusted heart rates were significantly lower during push-button Stroop recovery and during verbal Stroop. Blood pressure, T-wave amplitude, finger pulse amplitude and pulse transit time responses were unaffected by exercise training. It was concluded that participation in a short-term, moderate intensity aerobic exercise training program may have a cardioprotective effect by significantly reducing absolute and baseline-adjusted heart rate responses to stressors.


Basic emotions reflected in EEG-coherences. The differentiation of basic emotions by means of EEG power spectra has been discussed extensively by Machleidt et al. (1989). The present contribution concentrates on the interhemispheric coupling of different EEG-signals as depending on the modulation of these emotions. In the first part the estimation and interpretation of squared coherence spectra is outlined. Results from this technique are presented in the following section. Intention, Aggression and Joy are mainly characterized by an increase of alpha-coherence, whereas a decrease is seen for Anxiety and Sorrow. These effects showed a widespread distribution.


Distributions of the Nd and P300 in a normal sample. To obtain objective criteria for assessing the attentional and cognitive functioning of psychiatric populations, we attempted to standardize values of two components in Event-Related Potentials (ERPs), namely the attention-related negative potential (Nd) and the P300, in normal populations. The study consisted of 100 healthy volunteers (50 females, 50 males) who were given the task of making dichotic syllable discriminations requiring key-press responses. Their ages ranged between 18 and 59 years (mean +/- S.D., 32.3 +/- 11.3 years). Nd was found to be maximum in the Fz region, P300 being maximum in the Pz region. The means and standard deviations of Nd and P300 areas in their maximum regions were 554.1 +/- 307.8 microV ms and 2148.5 +/- 1248.5 microV ms, respectively. The transformation plot for symmetry indicated the suitable power of transformation to be 1/2 for both Nd and P300 distributions. After being transformed into square-root values, the distribution patterns of Nd and P300 areas were examined. When the lower limit of normal values was tentatively assigned to mean -2 S.D. using square-root transformed data for both Nd and P300, 97% of the subjects were found to display values above the lower normal limit for Nd, and 98% for the P300. Neither, Nd nor P300 areas correlated with age, while P300 latencies displayed a weak positive correlation with age. Females displayed relatively larger values than males for Nd and P300 areas and P300-peak amplitudes. However, the differences between females and males were not statistically significant. Females and males showed nearly equal P300-peak latencies.


Evoked potential topography in major depression. I. Comparisons with nonpatients and schizophrenics. This study compared evoked potential (EP) topography in major depression (MD), schizophrenia and nonpatient controls. EPs to four kinds of stimuli were recorded from 15 locations. Patients were 69 MDs and 52 schizophrenics, currently unmedicated. EP waveforms of 195 controls were subjected to principal component factor analysis (PCA). The structures of 32 factors so extracted have been shown to encompass the data space of disparate groups; they were used to compute factor scores for all subjects. Age- and gender-matched groups were compared. Factor scores were normalized across leads (Z-transform) to distinguish between topographic and mean level differences. Topographic differences (P < 0.05) between MD and controls were demonstrated for scores of 8 factors, with 2 others at P = 0.053. Unlike those for schizophrenia/control comparisons, these topographic differences did not converge regionally in MD. EP findings were not related to duration of withdrawal from drugs. There were few differences between bipolar and unipolar patients. Topographies of 5 factors differed between MDs and schizophrenics; these involved all modalities and reflected long latency, cognition-related events, such as P300. These topographic differences were antero-posterior (AP); values were greater posteriorly in MDs and anteriorly in schizophrenics. Deviant AP gradients appear specific to MD; gradients were similar in schizophrenics and controls.


Evoked potential topography in major depression. II. Comparisons between subgroups. Brief Psychiatric Rating Scale (BPRS) ratings of 69 patients with major depression (MD) were employed in an attempt to define subgroups of MD with more homogeneous evoked potential (EP) findings than the MD group as a whole. Correlations were computed between 6 BPRS ratings and scores for 32 EP factors; 14 correlations were significant. These indicated mainly that EP values were related to severity of depression. When age- and gender-matched groups of MDs with above- and below-median depressive mood (D) ratings were compared with controls, 3 of the 10 factors differing significantly between groups gave evidence of two different subgroups of MD. EPs of these subgroups differed from those of controls in opposite directions. Such bidirectional differences from normal suggest differing pathophysiology in the subgroups and support the multiple process view of depression.


AERPs and clinical evolution of thought disorders over five years. In a selective attention task, 21 Subjects detected rare randomized targets (P = 0.02) in a set of randomized standard tones. In one condition, Subjects focused their attention and detected targets in one ear, ignoring the other ear, and vice versa in the next condition. AERPs (auditory event-related potentials) were recorded at 5 electrode sites (10-20 system), at Fz, Cz, Pz, C3, C4, in two conditions varying speed of stimulation (randomized interstimulus intervals of 250-750 ms and 750-1500 ms). One group of 7 schizophrenics with the major syndrome of formal thought disorder (+FTD) was compared to 7 schizophrenics without the FTD syndrome (-FTD), and to 7 controls. The schizophrenic group was matched for age, education, sex, medication, hospitalization and intelligence score on abbreviated WAIS test. Ss were re-tested after 5 years following identical experimental and counterbalancing method to the pre-test. At re-test, similarly to pre-test, schizophrenics' AERPs showed smaller amplitudes, longer latencies, smaller attention effects than normals. -FTD schizophrenics showed intermediate values between the +FTD patients and normals. At retest, +FTD schizophrenics showed an aggravation of these AERP abnormalities while -FTD patients seemed to improve with larger amplitudes, faster latencies and better attention effects than at pre-test. Differential correlations between clinical and AERP indices indicated a dissociation between neurophysiological and clinical evolution: factors of dissociation included Andreasen's positive and negative indices of thought disorder, neuropsychological indices on the Luria-Nebraska scales, and severity of psychotic symptoms.


Computerized EEG topography findings in schizophrenic patients before and after haloperidol treatment. An increase of delta and fast beta activity in schizophrenic patients when compared with normal controls has been consistently reported. Topography of these abnormalities, in particular a possible frontal localization of delta, and their relationship to drug treatment and clinical status are still debated. In order to assess these issues, a multilead CEEG investigation was carried out in a group of 20 DSM-III-R schizophrenics, both before and after haloperidol treatment. All findings are described in terms of amplitude and relative power. Drug-free schizophrenics, when compared with a group of normal controls, showed a generalized increase of delta and fast beta, and a decrease of alpha 2 relative power. After acute treatment, patients showed a significant decrease of delta, and an increase of theta 2, beta 1, and beta 2. After 28 days of haloperidol treatment, similar changes were observed for delta, together with an increase of alpha 1, and a decrease of fast beta.


An EEG computerized system for the evaluation of hypnotic drugs. Digital recording of sleep EEG allows computer analysis and quantitative evaluations of sleep disorders and pharmacological effects. A system for polygraphic signal acquisition and storage, which performs a Fourier transform to compute series of spectra representing the evolution of EEG frequency composition through different sleep stages is described. The time course of spectral descriptors like relative band power is used to study the cyclic patterns of sleep and to compute the DSRI (Delta Sleep Regularity Index), a synthetic measure of sleep quality. The method is compared with conventional sleep scoring and examples of applications to normal, pathological and pharmacological conditions are shown. The topographical distribution of spectral parameters is analyzed by means of mapping techniques, allowing the detection of regional variations of EEG in specific pharmacological conditions.


Modulation of somatosensory evoked potentials during isometric contraction in relation to hand use. The aim of the study was to assess the effect of the hand used on the modulation of somatosensory evoked potentials (SEPs) during isometric contraction. SEPs to median nerve stimulation were assessed during dynamic (increase and decrease of force) and hold phases of isometric contractions. The experiments were carried out with the right or left hand. The changes in the SEP amplitude were found to vary with the hand used. When isometric contractions were performed by the right hand the amplitudes of the later components diminished during the dynamic phases, except for the component N140-P190 which increased. The amplitude of N55-P100 diminished during both the dynamic and hold phases. When isometric contractions were performed by the left hand the amplitudes of the early components diminished during the dynamic phases. These results show that the changes in SEP during isometric contraction depend on the hand used.


Influence of fish meal and supplemental fat on performance of finishing steers exposed to moderate or high ambient temperatures. Ninety-six Hereford x Angus steers (mean initial BW = 295 kg) were used in two growth experiments conducted at moderate and high ambient temperatures (AT), 48 steers per AT. Within each AT, calves were assigned to six dietary treatments consisting of a basal diet (approximately 60% corn and 20% grass hay) supplemented with either 0, 2.5, or 5% fat and with either soybean meal (SBM) or Menhaden fish meal (FM) included at levels such that a ratio of 16.3 kcal of NEm per kilogram of CP was maintained. Blood and ruminal fluid were collected 40 d before slaughter. During the final 28 d of the moderate AT experiment, apparent digestibility of dietary components was measured in four individually fed steers from each dietary treatment. Steer ADG was not affected by fat, and DMI and efficiency of gain were not affected (P > .10) by treatment. Average daily gain was lower for steers fed FM than for those fed SBM at moderate AT but higher at high AT (CP source x AT interaction; P < .05). Ruminal ratio of acetate to propionate declined linearly with increasing fat at moderate AT but was not affected by fat at high AT (fat x AT interaction trend; P = .08). Plasma urea N concentration increased linearly (P < .05) with increasing fat and was higher (P < .05) in steers kept at high than in those kept at moderate AT. Although apparent digestibility was not altered in steers fed FM, DM and NDF (P < .05) and ADF (P = .07) digestibility decreased with increasing fat in steers fed SBM (CP source x fat interaction).(ABSTRACT TRUNCATED AT 250 WORDS)


Relationship of milk production, milk expected progeny difference, and calf weaning weight in angus and simmental cow-calf pairs. Milk EPD, used to predict the milk production potential of a parent's daughters, have been reported by all major cattle breed associations. Our objectives were to determine the relationship of milk EPD of a dam to actual milk production (both fluid and components) and offspring weaning weight. Angus (AN; n = 114) and Simmental (SM; n = 82) cows were machine-milked at approximately 60, 104, and 196 d postpartum after overnight calf removal. In addition, one herd of AN was also milked at approximately 35 and 145 d postpartum. A lactation curve was fitted to these measurements to estimate total milk production during lactation. Simple correlations between 205-d total milk yields (TMY) and adjusted 205-d calf weaning weight (WW) were .30 (P < .001) and .47 (P < .001) for AN and SM, respectively. Furthermore, milk EPD was positively correlated to adjusted WW (r = .38 P < .001; r = .39, P < .001) and TMY (r = .32, P < .001; r = .44, P < .001) for AN and SM cows, respectively. A 1-kg change in TMY changed WW by .014 +/- .006 kg (P < .001) in AN and by .032 +/- .009 kg (P < .001) in SM. A 1-kg change in milk EPD resulted in a 4.85 +/- 1.14 kg change in WW (P < .001) in AN and a 3.74 +/- 1.73 kg (P < .05) change in SM. Corresponding changes in TMY were 42.1 +/- 16.6 kg (P < .01) and 69.3 +/- 16.0 kg (P < .001) for AN and SM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)


Effect of frame size, muscle score, and external fatness on live and carcass value of beef cattle. Commercial slaughter steers (n = 329) and heifers (n = 335) were selected to vary in slaughter frame size and muscle thickness score, as well as adjusted 12th rib fat thickness. After USDA carcass grade data collection, one side of each carcass was fabricated into boneless primals/subprimals and minor tissue components. Cuts were trimmed to 2.54, 1.27, and .64 cm of external fat, except for the bottom sirloin butt, tritip, and tenderloin, which were trimmed of all fat. Four-variable regression equations were used to predict the percentage (chilled carcass weight basis) yield of boneless subprimals at different fat trim levels (.64, 1.27, and 2.54 cm) as influenced by sex class, frame size, muscle score, and adjusted 12th rib fat thickness. Carcass component values, total carcass value, carcass value per 45.36 kg of carcass weight, and live value per 45.36 kg of live weight were calculated for each phenotypic group and external fat trim level. Carcass fatness and muscle score had the most influence on live and carcass value (per 45.36 kg weight basis). Carcasses with .75 and 1.50 cm of fat at the 12th rib were more valuable as the trim level changed from 2.54 cm to .64 cm; however, for carcasses with 2.25 cm of fat at the 12th rib, value was highest at the 2.54 cm trim level. Value was maximized when leaner cattle were closely trimmed. There was no economic incentive for trimming light-muscled or excessively fat carcasses to .64 cm of external fat.


The effectiveness of the best linear unbiased prediction of beef sires using field data collected from small farms. Beef sire evaluation using BLUP was investigated under field conditions at small-scale farms. The 6,848 records on fattened Japanese Black cattle steers were obtained from 1981 through 1987. The average number of steers in the subclass of market-year-farm was 5.2. A sire-maternal grandsire mixed model with relationships was used to analyze the data to yield BLUP for the sire and maternal grandsire effects. The regression coefficients of the realized value of progeny on the predicted value calculated using BLUP procedures for daily gain, carcass weight, and marbling score were 1.027, 1.054, and .917, respectively (i.e., the regression almost equaled 1). Therefore, BLUP was shown to be very effective in predicting offspring performance, even using field records collected from small-scale farms.


Animal model for genetic evaluation of multibreed data. Extension of beef cattle genetic evaluation procedures to multibreed data sets is proposed as a way to allow inclusion of crossbred animals into current analyses and to provide comparisons between purebred animals of different breeds. Previous papers dealing with multibreed BLUP have proposed sire or sire-maternal grandsire models. Because current models used in the beef industry are predominantly of the reduced animal model form, models were developed for animal model and reduced animal model mixed-model evaluations that would account for fixed and random additive genetic effects, along with fixed and random nonadditive genetic effects for populations with heterogeneous means and variances.


Increased litter size in Rambouillet sheep: I. Estimation of genetic parameters. The variance and covariance components needed to estimate heritabilities of and genetic correlations among litter size, ovulation rate, scrotal circumference, and BW in a flock of Rambouillet sheep were estimated using REML via an expectation-maximization type algorithm. The heritability estimates from univariate analyses were .14, .21, .25, .36, and .15 for litter size, ovulation rate, scrotal circumference, 180-d BW of females, and 180-d BW of males, respectively, and average heritability estimates from bivariate analyses were .19, .20, .20, .34, and .10 for litter size, ovulation rate, scrotal circumference, 180-d BW of females, and 180-d BW of males, respectively. The genetic correlation between litter size and ovulation rate was near unity. Body weight in ewes had a moderate genetic correlation with both litter size (.22) and ovulation rate (.20) and a low residual correlation with both litter size (.03) and ovulation rate (.09). The genetic correlation between BW in rams and scrotal circumference was 0, whereas the residual correlation was .71. The genetic correlations of scrotal circumference with litter size and ovulation rate were -.25 and +.20, respectively.


Increased litter size in Rambouillet sheep: II. Expected responses from alternative selection criteria. The variance and covariance components estimated from an experimental flock of Rambouillet sheep were used to predict response in litter size to direct and indirect selection. Indirect traits considered were ovulation rate and scrotal circumference. Ovulation rate was the most useful indirect selection criterion for genetic improvement of litter size. Expected response in litter size to indirect selection on ovulation rate was 93% as large as the expected response to direct selection on litter size. Selection based on an index of litter size and ovulation rate was estimated to produce 123% as much response in litter size as selection on litter size alone, and selection on an index of litter size, ovulation rate, and scrotal circumference resulted in 133% as much response in litter size as direct selection on litter size.


Performance of three tropical hair sheep breeds. The performance of three hair sheep breeds (Brazilian Somali, Morada Nova, and Santa Ines) was evaluated in the production environment of northeastern Brazil. Data from a total of 524 lambs sired by 21 rams and out of 190 ewes were analyzed. These data were collected from 1980 to 1983 at Sobral, Brazil from an experiment designed to compare performance of the three breeds. The traits included weights of lambs at birth, weaning, 8 mo, 10 mo, and yearling ages and ewe characters of weight at lambing (EWT), total lamb weight born (LWB), total lamb weight weaned (LWW), and prolificacy rate (PR). Differences (P < .01) among breeds were found for all characters. The Brazilian Somali, the smallest and slowest-gaining breed, was less sensitive to yearly variation than were the other breeds. The Santa Ines, the largest and fastest-gaining breed, was superior in LWB and LWW per ewe lambing. Averaged over the 4-yr period, the Morada Nova had the highest PR (1.82), and the Brazilian Somali and Santa Ines had similar PR (1.39 and 1.31, respectively). Environmental effects on PR due to yearly rainfall quantity and distribution pattern influenced lamb growth up to weaning and ewe reproduction performance. Breed x year (P < .05) interaction effects on PR were largely attributable to the Somali breed's exhibiting higher PR than the Santa Ines and Morada Nova breeds during the relatively wet years of 1981 and 1982.


Technical note: a noninvasive procedure for measuring goat heart rates. Heart rates were obtained simultaneously from FM radio transmitters and heart rate monitors externally mounted on unanesthetized and unrestrained mixed-breed goats. Data from transmitters were highly correlated (r = .92, P < .0001) with data from monitors and the percentage difference in heart rates between the two devices was less than that observed between animals. Analyses also revealed that radio transmitters provided a reliable, repeatable, and valid method for the noninvasive measurement of goat heart rates.


Measures of libido and their relation to serving capacity in the ram. The purpose of this study was to determine whether the ejaculation rate (serving capacity) of sexually experienced rams could be estimated by selected measures of sexual libido when rams were exposed to estrous ewes under conditions that prevented copulations. Twenty-four crossbred rams selected for either high or low rates of copulation were exposed to two restrained estrous ewes under three treatment conditions that 1) permitted the full range of precopulatory and copulatory behaviors, 2) permitted precopulatory behaviors and mounting but precluded copulation, or 3) permitted precopulatory behaviors but not mounting or copulation. Frequencies of precopulatory behaviors (bouts of leg-kicking and anogenital sniffing) in each of the three treatment conditions and mounting frequency in Treatment 2 occurred in proportion to the ram's characteristic ejaculation rate (P < .001), suggesting that the mating potential of rams can be estimated under conditions that preclude copulation. Frequencies of precopulatory behaviors and mounting were lower when the rams were allowed to copulate, due largely to periods of sexual inactivity after ejaculations.


Influence of trenbolone acetate combined with estradiol-17 beta on growth performance, body characteristics, and chemical composition of goat kids fed milk and slaughtered at different ages. The effects of anabolic agents (5 mg of estradiol-17 beta + 30 mg of trenbolone acetate) on body characteristics and chemical composition of gain were studied in 58 intact male goat kids fed milk replacer. Four kids were slaughtered at 7 d of age to constitute the initial group. The other kids were allotted in a 2 x 3 factorial arrangement with slaughter age (41, 49, and 56 d of age) and treatment (control and implanted at 21 d old) as factors. Energy intake decreased during the first 4 wk after treatment; implanted kids had the same ADG as controls but a better energy efficiency (P < .05). During the last week of the trial, energy intake was the same; treated kids tended (P < .10) to have a higher empty body gain (EBG). Anabolic agents increased carcass (P < .10) and hide proportions (P < .01) in empty BW and in EBG for all groups (except for carcass at 56 d old). Anabolic agents reduced the contribution of adipose tissues (P < .05), empty digestive tract (P < .05), and other organs (P < .01) to EBG. At all slaughter ages, the chemical composition of carcass and hide wet tissues, all dissectible adipose tissues, and EBG were altered by treatment. In these tissues (except for mesenteric fat tissue), water content increased and lipid content decreased (P < .05), but these effects diminished with age. Expressed on a DM basis, the CP content of the treated carcasses was increased in all groups (P < .05). Implanting high doses of steroids altered nutrient partitioning, which reduced fat and increased water and protein in the body.


Performance, plasma hormones, histochemical and biochemical muscle traits, and meat quality of pigs administered exogenous somatotropin between 30 or 60 kilograms and 100 kilograms body weight. Forty-five Large White barrows were injected daily i.m. with either excipient from 30 to 100 kg BW (CTRL), excipient from 30 to 60 and porcine somatotropin (pST; 100 micrograms/kg BW) from 60 to 100 kg BW (pST-60), or pST (100 micrograms/kg BW) from 30 to 100 kg BW (pST-30). Somatotropin accelerated overall growth rate (+4 and +9% for pST-60 and pST-30, respectively), increased longissimus (+10.3 and +14.7%) and semitendinosus (+17 and +13%) muscle weights, and decreased backfat (-49 and -58%) and leaf fat (-49 and -53%) weights. The administration of pST resulted in a similar increase in muscle fiber size for all fiber types in both longissimus (LM) and semispinalis (SS) muscles (+21%). Somatotropin had otherwise little effect on muscle fiber types and biochemical traits of LM, whereas dramatic changes were observed in SS. The relative area occupied by Type IIB fibers was increased (+22 and +29%) and that of Type I fibers was decreased (-10 and -15%). In pST-30 animals, myosin ATPase activity (+15%) and native myosin fast isoform proportion (+10%) were augmented, and energy metabolism was more glycolytic (lactate dehydrogenase: +25%) and less oxidative (citrate synthase: -13%; beta-hydroxyacyl-CoA dehydrogenase: -21%). Compared to CTRL animals, administration of pST increased muscle water concentration (LM: +.8 and +1.1%: SS: +3.3 and +3.3%) and decreased intramuscular fat (LM: -29 and -27%; SS: -39 and -50%). The pH measured 45 min and 24 h postmortem, glycogen content, reflectance, and index of light diffusion were mostly not affected by pST treatment. In conclusion, pST had a very favorable effect on growth performance without any important effect on meat quality traits except for the reduction in intramuscular lipid content. The results indicated that the effects of pST on muscular histochemical and biochemical characteristics were different in LM and SS muscles.


The effect of live weight gain and live weight loss on body composition of merino wethers: chemical composition of the dissected components. Chemical composition of the dissected side parts and dissected side was measured during live weight gain (LWG) and live weight loss (LWL) to determine effects on the chemical composition of the dissected side parts. Thirty-five Merino wethers had ad libitum access to the experimental diet (17.23% CP and 12.09 MJ/kg of DE) to grow from 23.0 to 33.0 kg live weight and then were fed to lose a total of 10 kg in three periods of 25 d each at the rate of 133 g/d. Groups of five animals were slaughtered at live weights of 23.0, 26.3, 29.6, and 33.0 kg during LWG and 29.6 kg (first period), 26.3 kg (second period), and 23.0 kg (third period) during LWL. The greater dissected side weight in LWL animals than in LWG animals at 23.0 kg of live weight was due to the significantly greater chemical fat (P < .05) in the LWL animals than in the LWG animals at 23.0 kg. There were no significant differences between treatments in the protein and water weights in the dissected side. The general increase in the chemical fat in the dissected side of the LWL animals was due to the significant increase in the chemical fat in the muscle (P < .01) and bone (P < .01, 23.0 and 26.3 kg and P < .05, 29.6 kg) at each common slaughter weight and subcutaneous fat (P < .05), intermuscular fat (P < .05) kidney and channel fat (P < .05), and total side fat (P < .01) at 23.0 kg.(ABSTRACT TRUNCATED AT 250 WORDS)


Partial purification of somatotropin receptors from pig liver: they arise from a single somatotropin receptor messenger RNA transcript. Specific binding sites for porcine somatotropin (pST) have been identified in pig liver microsomal membranes. Little information, however, is available about the size and number of ST receptor (ST-R) forms present. Therefore, the present study was conducted to characterize ST-R in pig liver using two approaches. In the first set of experiments, cross-linking of [125I]bST (bovine ST) to microsomal membranes, followed by gel electrophoresis under reducing conditions, revealed the presence of a predominant protein of 107 kDa and four other proteins of 71, 52, 40, and 26 kDa. In a second set of experiments, ST-R were partially purified using affinity chromatography. Binding studies indicated that there was an approximately 1,800-fold purification compared to liver homogenate. Two specific proteins of 107 and 40 kDa were detected after crosslinking of [125I]bST to partially purified ST-R. Northern blot analysis revealed that these proteins arise by posttranslational modification of a single 4.2-kilobase somatotropin receptor messenger RNA transcript. Although the present study indicates that several forms of ST-R are present in pig liver, it is not clear what physiological role these different ST-R play in mediating the hepatic effects of pST. It is evident, however, that the smaller proteins are generated from the 107-kDa protein, which is the predominant isoform present in liver microsomal membranes.


Effects of the alpha 2-adrenoceptor agonist guanfacine on growth and thermogenesis in mice. Guanfacine is an alpha 2-adrenoceptor agonist with antithermogenic properties. A single treatment of guanfacine caused a dose-related reduction in metabolic rate. The maximum reduction was 40%, and a dose of .5 mg/kg was close to that required to produce half this effect. It was determined whether the antithermogenic action of guanfacine would result in increased growth rate in mice. In animals treated once daily for 10 d (0, .125, .5, or 2 mg/kg), the drug caused dose-related reductions in feed intake, weight gain, and feed conversion efficiency. In a further experiment, mice were fed a restricted quantity of feed and treated for 14 d with guanfacine (.5 mg/kg twice daily). Because of repeated dosing, the antithermogenic effect of the drug was attenuated, so that metabolic rate was not lower in treated mice at the end of the experiment. Control and treated mice ate all the feed offered, but the guanfacine-treated group gained 2.9 g less weight (P < .01) than the controls. Half this difference in BW was accounted for by body water (P < .1), whereas body energy content was also reduced by the drug (P < .05). In a final experiment we sought possible sources of energy loss. Mice were treated with guanfacine (.5 mg/kg) three times over 24 h. Severe glucosuria was observed in the guanfacine-treated mice, with a tendency also toward increased output of fecal energy. We have confirmed that guanfacine has a powerful, if short-term, antithermogenic action. However, in mice, other effects of the drug on energy metabolism result in weight loss rather than growth stimulation.


The effect of porcine somatotropin supplementation in pigs on the lipid profile of subcutaneous and intermuscular adipose tissue and longissimus muscle. The effect of porcine somatotropin (pST) on the lipid profiles of adipose tissue and muscle was investigated. Sixteen crossbred barrows were injected daily with either 3 mg of pST or a placebo. After slaughter, total lipid and fatty acid composition of raw subcutaneous (SC) adipose and intermuscular (IM) adipose tissue and longissimus muscle were determined. The SC adipose tissue from pST-treated pigs had a 7.5% decrease in total lipid content; specific fatty acids 16:0, 18:0, and 18:1(n-9)c decreased most. The IM fat from pST-treated pigs had lower levels of 16:0 and 20:0. There was no effect of pST treatment on the lipid profile of the longissimus muscle. The data suggest that pST treatment produces small but significant changes in the saturated fatty acid content of adipose tissue in pigs.


Use of bioelectrical impedance to predict leanness of Boston butts. The objective of this research was to make available bioelectrical impedance technology for the prediction of kilograms of lean and kilograms of fat-free muscle of Boston butts. Seventy butts were removed from 70 pork carcasses according to standard procedures (NAMP, #406), with the exception that the fat was not removed. After the weight in kilograms (BUTT) and internal temperature in degrees centigrade (TEMP) were recorded, each butt was measured for resistance (Rs, ohms), reactance (Xc, ohms), and distance (L, centimeters) between detector terminals four different ways: parallel or perpendicular to the top of the carcass and on either lean surface or fat surface of the cut. Each cut was physically separated into lean, fat, and bone. Chemical composition (moisture, protein, and fat) was determined on the lean portion. Variable selection analysis was used to develop equations for predicting kilograms of lean and kilograms of fat-free muscle of Boston butts. Results of measurements of the four sites were quite similar; however, measuring perpendicularly on the lean surface is recommended. The prediction equation for kilograms of lean from measurements thus taken is as follows: .461-.0304 x TEMP + .576 x BUTT - .0118 x Rs + .00845 x Xc + .0630 x L. The respective coefficients of these independent variables for predicting kilograms of fat-free muscle are .537, -.0415, .479, -.0139, .00804, and .0764. In an industry application of these coefficients, recording temperature would not be imperative because the temperature range would be sufficiently narrow to render temperature of little practical influence when separating butts according to leanness.(ABSTRACT TRUNCATED AT 250 WORDS)


The effect of postmortem time of injection and freezing on the effectiveness of calcium chloride for improving beef tenderness. Three experiments were conducted to determine the effect of freezing and time postmortem on the effectiveness of injecting CaCl2 to tenderize beef. In Exp. 1, longissimus muscle treatments included 1) control 0 h, 2) CaCl2-injected 0 h, 3) control 24 h, and 4) CaCl2-injected 24 h. Injection consisted of .3 M CaCl2 at 10% by weight. Injecting CaCl2 at 24 h postmortem reduced (P < .05) shear force requirements compared with the 24 h control but did not (P < .05) tenderize meat as much as injecting at 0 h. In Exp. 2, longissimus muscle treatments included the following: 1) aged 2 d; 2) aged 7 d; 3) frozen d 1, thawed, aged 6 d; 4) CaCl2-injected d 1, aged 6 d; 5) frozen d 1, thawed, CaCl2-injected, aged 6 d; and 6) CaCl2-injected d 1, frozen, thawed, aged 6 d. Injection alone at d 1 or freezing, then thawing and injecting resulted in the lowest (P < .05) shear force requirements. In Exp. 3, longissimus muscle treatments included the following: 1) aged 1 d; 2) aged 7 d; 3) CaCl2-injected 0 h, aged 7 d; 4) CaCl2-injected d 1, aged 6 d; 5) frozen d 1, thawed, aged 6 d; and 6) frozen, thawed, CaCl2-injected, aged 6 d. Both d-1 injection alone and freezing, thawing, then injecting resulted in meat with shear force requirements similar to those of 0-h injected meat. The effect of treatments on cooking loss was inconsistent. Treatments that reduced shear force also reduced (P < .05) calpain and calpastatin activity proportionately.(ABSTRACT TRUNCATED AT 250 WORDS)


Tracer studies of urea kinetics in growing pigs: I. The effect of intravenous infusion of urea on urea recycling and the site of urea secretion into the gastrointestinal tract. Four gilts (average BW 80 kg) were used in the first experiment to study the effect of i.v. infusion of urea on urea kinetics by means of a radioisotope dilution technique. The pigs were fed twice daily 600 g of a cornstarch-based diet formulated to contain 16% CP by supplementation with isolated soy protein. Infusion of urea, compared with saline, increased (P < .05) plasma urea concentration, urea pool size, urea entry, urea excretion, and urea degradation rates; urea turnover rate and urea space were not affected (P > .05). Expressed as a percentage of the total entry rate, a lower (P < .05) percentage of urea was recycled in pigs infused with urea. The urea infused was almost completely excreted in urine, so there were no differences (P > .05) in N balance. In the second experiment, four gilts (average BW 40 kg), fitted with ileocecal reentrant cannulas, were used to determine whether the upper or the lower digestive tract represents the preferential site of urea secretion in pigs. Two pigs were fed twice daily 600 g of a cornstarch-based diet, formulated to contain 16% CP from soybean meal. The other two pigs were fed the same diet in which 15% cornstarch was replaced by beet pulp. After labeling the body urea pool of one pig on each treatment with [15N]urea, the reentrant cannulas were disconnected to prevent the flow of digesta from the small into the large intestine.(ABSTRACT TRUNCATED AT 250 WORDS)


Tracer studies of urea kinetics in growing pigs: II. The effect of starch infusion at the distal ileum on urea recycling and bacterial nitrogen excretion. Six gilts, with an average BW of 70 kg, were fitted with a simple T-cannula at the distal ileum to study the effect of continuous starch infusion on urea kinetics by means of a radioisotope dilution technique. The pigs were fed twice daily 600 g of a cornstarch-based diet formulated to contain 16% CP by supplementation with isolated soy protein. Infusion of starch, compared with water, decreased (P < .05) plasma urea concentration, urea pool size, and entry, excretion, and degradation rates; urea turnover rate and urea space were not affected (P > .05). Expressed as a percentage of total entry rate, approximately 40% of urea was recycled into the digestive tract in both infusion treatments. The stimulation of microbial fermentation in the large intestine resulted in an increase (P < .05) in fecal N excretion, which was mainly due to an increased excretion of bacterial N. This increase could not be attributed to a greater secretion of urea into the large intestine and its subsequent utilization by the intestinal microflora. The increased bacterial N assimilation after starch infusion led to a reduction in ammonia absorption from the large intestine, which in turn was reflected by a reduced urinary N excretion. As a result, the overall N balance was not affected. In a second experiment, two barrows, with an average BW of 80 kg, were fed twice daily 1.4 kg of a cereal-based diet. The body urea pool of both pigs was labeled with a single injection of 1 g and 2 g of [15N]urea, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)


Effects of exogenous emulsifiers and fat sources on nutrient digestibility, serum lipids, and growth performance in weanling pigs. Three experiments were conducted to determine whether emulsifiers improve utilization of fat from diets for early-weaned pigs. In Exp. 1, 96 weanling pigs (17 d old) were used in metabolism cages, with main effects of fat source (soybean oil, tallow, lard, and coconut oil) and emulsifier treatment (no emulsifier, lecithin, and lysolecithin as 10% of the added fat). Soybean oil and coconut oil were more digestible than tallow and lard (P < .001). Tallow was more digestible when lecithin and lysolecithin were added (P < .007), and pigs fed lecithin had lower serum triglycerides and cholesterol than pigs fed lysolecithin (P < .03). In Exp. 2, 270 weanling pigs (21 d old) were used in a growth assay. Treatments were 1) control diet; 2) Diet 1 with soybean oil; 3) Diet 1 with tallow; 4, 5, and 6) Diet 3 with lecithin replacing 5, 10, and 30% of the tallow, respectively; and 7, 8, and 9) Diet 3 with lysolecithin replacing 5, 10, and 30% of the tallow, respectively. At d 14 of the experiment, digestibility of tallow was improved more by lecithin than lysolecithin (P < .008). For the total experiment (d 0 to 35), the control pigs had poorer gain:feed ratio than did the pigs fed the fat sources (P < .002). In Exp. 3, 420 weanling pigs (21 d old) were used. Treatments were 1) control diet with soybean oil; 2) Diet 1 with tallow; and 3, 4, and 5) Diet 2 with 10% of the added fat as soybean oil, lecithin, or monoglyceride, respectively. Adding soybean oil, lecithin, and monoglyceride to tallow increased digestibility of total fat (P < .07). From d 0 to 14, pigs fed soybean oil gained weight faster than pigs fed the other treatments (P < .06), and pigs fed tallow without emulsifiers had the lowest ADG. Considering all experiments, addition of emulsifiers increased digestibility of nutrients but had minimal effect on growth performance.


Effects of feeding diets containing endophyte-infected fescue seed on luteinizing hormone secretion in postpartum beef cows and in cyclic heifers and cows. Two experiments were conducted to investigate the effect of feeding endophyte (Acremonium coenophialum)-infected fescue (Festuca arundinacea Shreb.) seed on LH secretion in postpartum beef cows and in cycling heifers and cows. In Exp. 1, spring-calving primiparous Angus cows (n = 16) were pair-fed for 75 d diets that contained endophyte-free or endophyte-infected (95%) fescue seed that contained 1.3 micrograms/g of ergovaline and 5.2 mg/g of saturated pyrrolizidines. Serial blood samples for basal and GnRH-stimulated serum LH analysis were obtained on d 7, 28, 42, and 56 of the study. The endophyte had no effect on LH secretion (basal, pulse frequency, and amplitude) or milk production. Average daily gain was decreased (P < .05) in cows that consumed infected fescue seed compared with controls (-.20 vs -.01 kg, respectively). Basal serum prolactin concentrations were reduced (P < .01) in treated compared with control cows (8.9 vs 25.4 ng/mL, respectively) on d 70. In Exp. 2, cycling Angus heifers (n = 8; age = 2 yr) and cows (n = 8; age = 4 yr) stratified by age were pair-fed for 40 d diets that contained the noninfected or the highly infected fescue seed. Estrus was synchronized by prostaglandin F2 alpha (d 18 and 28). Serial blood samples for serum LH analysis were obtained on d 28 (luteal phase) and d 30 (follicular phase). The endophyte did not affect LH (P > .28) or prolactin (P > .16) secretion, whereas ADG was decreased (P < .05) in treated compared with control animals (.32 vs .70 kg/d, respectively).


Effect of heat-stress on bovine embryo development in vitro. Chronic elevation of uterine temperature has long been known to increase embryo mortality in dairy cattle. Short-term elevation in temperature of mouse embryos to 43 degrees C (acute) has been shown to induce intracellular production of heat-shock proteins. In this study, in vitro development of bovine embryos was assessed during short-term (60 h) coculture with oviduct epithelial cells at 38.6 degrees C (T1), 40 degrees C (T2), 38.6 degrees C after a prior pulse treatment (20 min) at 43 degrees C with 5% CO2 (T3), or 38.6 degrees C after a prior pulse treatment (20 min) at 43 degrees C with 100% CO2 (T4). During incubation, embryos cocultured at 40 degrees C had a greater (P < .05) mean embryo development score at 36 h than embryos cocultured at 38.6 degrees C. At 60 h of incubation, embryo development scores were greater (P < .05) for embryos cultured at 38.6 degrees C than for those cocultured at 40 degrees C. The number of embryos hatched at 60 h was similar after coculture at 38.6 degrees C (T1) or a prior pulse treatment with 5% CO2 and 43 degrees C (T3), but the embryo development score at 60 h was greater (P < .05) for the pulse-treated embryos. Embryos in T4 had greater (P < .05) embryo development scores than did T1 embryos from 36 through 60 h. Pulse treatment (T4) resulted in a greater (P < .05) number of hatched embryos at 60 h than T1, T2, and T3. These results indicate a detrimental effect of a chronic elevation in temperature that was evident shortly after embryo hatching.(ABSTRACT TRUNCATED AT 250 WORDS)


Effects of feeding ponderosa pine needles during pregnancy: comparative studies with bison, cattle, goats, and sheep. Four experiments were conducted to determine the effect of feeding dried pine needles (Pinus ponderosa; PN) on the abortion rate of ruminants. In Exp. 1, cattle were fed 5.4 kg of PN daily for 21 d starting at 116, 167, 215, or 254 d of pregnancy. The PN did not cause abortions when started at 116 d; thereafter, the percentage of cows that aborted increased linearly, and the interval to abortion decreased linearly (both P < .01); all cows fed PN beginning at 254 d aborted. In Exp. 2, cattle were fed .7, 1.4, or 2.7 kg of PN for 21 d or 2.7 kg for 1 or 3 d. Sheep and goats were fed .8 and .5 kg of PN, respectively, starting at 121 d of pregnancy. The PN induced some abortions in cattle when fed for 1 (11%) or 3 (30%) d, but the abortion rate was greater (P < .01) when the PN were fed for longer periods of time (80, 90, and 100% aborted in 19, 17, and 10 d for .7-, 1.4-, and 2.7-kg doses, respectively). No goats or sheep aborted in response to PN feeding. Pregnancy rates during the next breeding season for cows that aborted in response to the PN were slightly higher than rates for control cows (94 vs 87%). In Exp. 3, buffalo (Bison bison) and cattle were fed 2.25 kg of PN from the same collection. Abortions were induced in all buffalo and cattle that were fed PN.(ABSTRACT TRUNCATED AT 250 WORDS)


Ovarian follicular characteristics, embryo recovery, and embryo viability in heifers fed high-fat diets and treated with follicle-stimulating hormone. Postpubertal beef heifers (n = 55) were used to examine the effects of high-fat diets, independently of energy intake, on nonesterified fatty acid and lipoprotein metabolic patterns, ovarian follicular dynamics, and embryo recovery/viability after FSH superstimulation. High-lipid (HL) diets (5.4% added fat) increased (P < .01) serum concentrations of cholesterol, but not of nonesterified fatty acids, during the 35-d period before FSH treatment. Development of medium-sized (5 to 9.9 mm) follicles was enhanced (P < .05) during this period in heifers fed the HL diet. The HL diet increased total cholesterol (P < .05) and progesterone (P = .14) concentrations in follicular fluid obtained at ovariectomy (n = 10) 60 h after the onset of FSH treatment, but neither estradiol-17 beta nor androstenedione was affected. Granulosa cells recovered from FSH-induced, estrogen-active follicles in heifers fed the HL diet produced greater quantities of progesterone (P = .06) and less estradiol-17 beta (P < .05) in vitro than did granulosa cells from heifers fed the normal lipid diet. Dietary treatment did not influence FSH-stimulated recruitment of medium and large follicles, number of ovulations, embryo recovery, or embryo viability. Data suggest that increments in dietary fat intake can alter specific aspects of ovarian steroidogenic potential and can increase the population of medium-sized follicles theoretically available for maturation and harvest during the estrous cycle. However, conditions that limited the latter process in the current experiment are not understood and require further investigation.


Combined effects of diet and cold exposure on insulin responsiveness to glucose and tissue responsiveness to insulin in sheep. Hyperglycemic clamp and hyperinsulinemic euglycemic clamp techniques were used to investigate effects of diet and cold exposure on insulin responsiveness to glucose and tissue responsiveness and sensitivity to insulin in adult rams. The sheep were fed a high-concentrate diet (80% concentrate and 20% roughage) and a high-roughage diet (20% concentrate and 80% roughage), both 70% above the ME requirement for maintenance, and were exposed to a thermoneutral environment (20 degrees C) and a cold environment (0 degrees C) for 2 wk. The estimated ME intake was greater (P < .01) for the high-concentrate diet than for the high-roughage diet. In the hyperglycemic clamp experiment, the ratio of the plasma insulin increment to the glucose infusion rate (insulin responsiveness to glucose) was lower during cold exposure than in the thermoneutral environment in sheep fed the high-concentrate diet but was unchanged in sheep fed the high-roughage diet. In the hyperinsulinemic euglycemic clamp experiment, the glucose infusion rate (tissue responsiveness to insulin) was higher (P < .01) for the high-concentrate diet than for the high-roughage diet, and it was also higher (P < .01) during cold exposure than in the thermoneutral environment, indicating that tissue responsiveness to insulin was intensified in sheep fed the high-concentrate diet during cold exposure associated with the higher energy intake. These results suggest that both reduced insulin responsiveness and enhanced tissue responsiveness to insulin in sheep exposed to cold were dependent on the type of diet.


Prolactin and luteinizing hormone secretion in the pregnant pig. Four pregnant, primiparous, crossbred gilts and six gilts from the same population that had been ovariectomized (OVX) for approximately 3 wk were placed in individual pens in an enclosed building. Blood samples were collected every 30 min for 12 h from all gilts via an indwelling jugular vein cannula when the pregnant gilts were at d 30, 50, 70, 90, and 110 of gestation. Serum was quantified for LH and prolactin (PRL) by RIA. The OVX gilts served as controls to ensure that any variations in serum LH and PRL concentrations observed in the pregnant animals were not due to environmental factors unrelated to pregnancy. Within the pregnant gilts, mean serum LH concentrations, mean basal serum LH concentration, and mean serum LH peak height were similar on all days; however, number of LH peaks on d 30, 50, and 70 were greater (P < .05) than on d 90 and 110, and number of LH peaks on d 50 was greater (P < .05) than that on d 70. Within the pregnant gilts, mean serum PRL concentration, mean basal serum PRL concentration, and mean PRL peak height were greater (P < .001) on d 110 than on all other days; however, number of PRL peaks were similar among days. Parameters of LH and PRL secretion in the OVX and pregnant gilts varied independently. Results of this study indicated that 1) LH secretion does not vary appreciably throughout pregnancy and 2) PRL secretion does not vary significantly during the first 90 d of pregnancy, after which it increases markedly on or before 110 d.


Influence of model and marker on digesta kinetic estimates for sheep. Several models and markers are available for digesta kinetic studies. In this study, kinetic estimates derived from chromium-mordanted hay or pellets were compared to estimates derived from rare earth markers (Yb, Dy, or Er) applied individually to samples. Twelve yearling rams (52 kg) were given ad libitum access to either hay or a commercial pelleted diet in a crossover experiment. Digesta kinetic estimates were obtained both by nonlinear analysis with two age-independent rates (G1G1) or with gamma time dependency in the fast compartment (G2G1 to G4G1) and by linear regression of natural log transformed fecal marker concentrations (LN method of estimate). Model did not influence total tract (P > .21) or ruminal mean retention times (P > .87). Partitioning of total retention time was similar (P > .21) for the LN, G3G1, and G4G1 models, but the G1G1 and G2G1 models did not adequately fit these data. Nonlinear models overestimated, and LN underestimated, fecal DM output by 9% (SEM = 4.7) for the hay diet. All the nonlinear models provided fecal DM output estimates that were within 5% of actual fecal DM output, but the LN model underestimated it by 18% (SEM = 3.3) for the pelleted diet. Ruminal outflow rate was slower (P < .01) and both ruminal and total mean retention time estimates were longer (P < .01) for Cr than for the rare earths. Despite the marker chosen, relative diet effects were similar. The three rare earth markers gave identical results for digesta kinetic estimates, indicating that they are useful for simultaneous study of more than one ingredient or particle, but direct comparison of rare earth and Cr-mordant passage rates is not advisable.


Sulfate supplementation of alpine goats: effects on milk yield and composition, metabolites, nutrient digestibilities, and acid-base balance. Effects of sulfate supplementation on milk yield and composition, ruminal and blood metabolites, acid-base status, and nutrient digestibilities were determined using 30 multiparous, lactating Alpine does. Goats were fed isonitrogenous diets containing .16 (basal), .26, or .36% S (DM basis) during a 13-wk lactation trial that coincided with wk 3 to 15 of lactation. During wk 16 to 17, four does from each treatment were placed in a metabolism crate to measure nutrient digestibility and balance. Feed intake, yield of 4% fat-corrected milk, and milk S content were not affected by added S, but the goats fed the .26% S diet had a trend of higher persistency of lactation (P < .20). During wk 10 and 15 of lactation, milk solids-not-fat percentage was higher (P < .10) for does fed the .26% S diet. Sulfur supplementation resulted in quadratic decreases in ruminal ammonia N (P < .05) in wk 15 and in plasma urea N in wk 10 and 15 (P < .05) but in linear increases (P < .05) in ruminal protein S concentrations throughout the experiment. Added S had little effect on blood acid-base status. Apparent digestibilities of DM, OM, ash, ADF, and GE were increased linearly (P < .10) by added S. The milk N:S ratio remained constant. Increasing S from .16 to .26% of diet DM was beneficial to lactating Alpine goats during early lactation.


A net carbohydrate and protein system for evaluating cattle diets: I. Ruminal fermentation. The Cornell Net Carbohydrate and Protein System (CNCPS) has a kinetic submodel that predicts ruminal fermentation. The ruminal microbial population is divided into bacteria that ferment structural carbohydrate (SC) and those that ferment nonstructural carbohydrate (NSC). Protozoa are accommodated by a decrease in the theoretical maximum growth yield (.50 vs .40 g of cells per gram of carbohydrate fermented), and the yields are adjusted for maintenance requirements (.05 vs .150 g of cell dry weight per gram of carbohydrate fermented per hour for SC and NSC bacteria, respectively). Bacterial yield is decreased when forage NDF is < 20% (2.5% for every 1% decrease in NDF). The SC bacteria utilize only ammonia as a N source, but the NSC bacteria can utilize either ammonia or peptides. The yield of NSC bacteria is enhanced by as much as 18.7% when proteins or peptides are available. The NSC bacteria produce less ammonia when the carbohydrate fermentation (growth) rate is rapid, but 34% of the ammonia production is insensitive to the rate of carbohydrate fermentation. Ammonia production rates are moderated by the rate of peptide and amino acid uptake (.07 g of peptide per gram of cells per hour), and peptides and amino acids can pass out of the rumen if the rate of proteolysis is faster than the rate of peptide utilization. The protein-sparing effect of ionophores is accommodated by decreasing the rate of peptide uptake by 34%. Validation with published data of microbial flow from the rumen gave a regression with a slope of .94 and an r2 of .88.


A net carbohydrate and protein system for evaluating cattle diets: II. Carbohydrate and protein availability. The Cornell Net Carbohydrate and Protein System (CNCPS) has a submodel that predicts rates of feedstuff degradation in the rumen, the passage of undegraded feed to the lower gut, and the amount of ME and protein that is available to the animal. In the CNCPS, structural carbohydrate (SC) and nonstructural carbohydrate (NSC) are estimated from sequential NDF analyses of the feed. Data from the literature are used to predict fractional rates of SC and NSC degradation. Crude protein is partitioned into five fractions. Fraction A is NPN, which is trichloroacetic (TCA) acid-soluble N. Unavailable or protein bound to cell wall (Fraction C) is derived from acid detergent insoluble nitrogen (ADIP), and slowly degraded true protein (Fraction B3) is neutral detergent insoluble nitrogen (NDIP) minus Fraction C. Rapidly degraded true protein (Fraction B1) is TCA-precipitable protein from the buffer-soluble protein minus NPN. True protein with an intermediate degradation rate (Fraction B2) is the remaining N. Protein degradation rates are estimated by an in vitro procedure that uses Streptomyces griseus protease, and a curve-peeling technique is used to identify rates for each fraction. The amount of carbohydrate or N that is digested in the rumen is determined by the relative rates of degradation and passage. Ruminal passage rates are a function of DMI, particle size, bulk density, and the type of feed that is consumed (e.g., forage vs cereal grain).


Kinetics of hydration and effect of liquid uptake on specific gravity of small hay and silage particles. Kinetics of hydration of ground hay and silage particles (2-mm screen), determined by a pycnometric technique, was best described by a two- and one-pool exponential model, respectively. Fractional rates of hydration of the large pool, detected in hay particles only, and of the small pool present in both hay and silage particles averaged .135 and .021 min-1, respectively. When hydration was complete, liquid associated with particles averaged 1.16, 1.90, and .83 g/g of insoluble DM for bromegrass hay, alfalfa hay, and alfalfa silage, respectively. Functional specific gravity, which accounts for the effect of associated gas volume, averaged 1.54, 1.46, and 1.54, but unit specific gravity, calculated to include the effect of gases and liquid of hydration, averaged 1.22, 1.14, and 1.26 for bromegrass hay, alfalfa hay, and alfalfa silage, respectively. Preservation of forage as silage not only lowered gas volume, but also reduced water-holding capacity, both of which contribute to greater unit specific gravity and faster rate of escape from the rumen. In addition, estimates of unit specific gravity of approximately 1.2 indicate that even in the absence of associated gas, hydrated forage particles would tend to escape the rumen at a slower rate than that achieved by more dense particles.


Ruminal biohydrogenation of linoleoyl methionine and calcium linoleate in sheep. Four ruminally and duodenally cannulated Hampshire wethers were used in a 4 x 4 Latin square experiment to determine whether linoleoyl methionine and calcium linoleate would increase duodenal flow of unsaturated fatty acids (C18:2 + cis C18:1). All animals received the same basal diet plus a treatment enclosed in gelatin capsules that were placed directly in the rumen. Of the four experimental treatments, one was a control (empty capsules) and three were 5 g of fatty acid equivalent as either free linoleic acid, calcium linoleate, or linoleoyl methionine. Linoleoyl methionine had the lowest ruminal disappearance of C18:2 + cis C18:1. Ruminal loss of unsaturated fatty acids from each supplement exclusive of feed unsaturated fatty acids was 69.8, 92.9, and 94.6% for linoleoyl methionine, free linoleic acid, and calcium linoleate, respectively. Duodenal flow of methionine also was higher for linoleoyl methionine than for control, free linoleic acid, or calcium linoleate (2.5, 1.7, 2.0, and 2.5 g/d, respectively). Plasma linoleic acid was higher for linoleoyl methionine than for control or free linoleic acid but was not different from calcium linoleate (22.0, 17.8, 18.9, and 20.2% of total fatty acids, respectively). Plasma methionine levels were not different among treatments. Intestinal disappearance of unsaturated fatty acids did not differ among treatments. Linoleoyl methionine resisted ruminal biohydrogenation and was digested normally in the intestine. Calcium linoleate did not escape biohydrogenation by ruminal bacteria.


Factors that affect ovarian follicular dynamics in cattle. Studies of ovarian follicular dynamics in cattle may lead to methods for improving fertility, for synchronizing estrus with more precision, and for enhancing superovulatory responses. Within an estrous cycle, two or three large (> 10 mm) follicles develop during consecutive waves of follicular growth. The last wave provides the ovulatory follicle, whereas preceding wave(s) provide follicles that undergo atresia. The life span of large follicles seems to depend on the pulsatile secretion of LH; decreased frequency of LH pulses results in atresia of large follicles. Aromatase activity in the walls of the largest follicles is greatest during the first 8 d of the estrous cycle and decreases by d 12. Steroidogenesis of the largest and second-largest ovarian follicles differs on d 5, 8, and 12 of the estrous cycle. Follicular dynamics are altered by negative energy balance and lactation. The number of large follicles and concentration of estradiol during the preovulatory period differs between postpartum lactating and nonlactating cows. Dietary fats stimulate follicular growth when they are fed to increase energy balance. Administration of bovine somatotropin decreases energy balance and has a differential effect on ovarian follicular responses; growth of the largest follicle does not change, but growth of the second-largest follicle is stimulated by somatotropin. Studies of follicular dynamics in lactating cows demonstrate changes in ovarian function associated with energy balance that may be related to inefficient reproductive performance of cows producing high yields of milk.


Pharmacokinetics in immature animals: a review. Differences in drug pharmacokinetics between newborn and adult mammals are reviewed. The pharmacokinetic alterations during the maturation process are related to changes in the pattern of absorption, distribution, metabolism, and renal excretion. The most pronounced feature in neonates vs adults is the prolonged elimination half-life of drugs. The main factors causing delayed elimination are under-developed renal clearance and immature metabolism of drugs. Special attention has to be paid to central nervous system depressants and to drugs that are extensively metabolized because they will accumulate with repeated dosing of newborn animals.


Factors that affect drug disposition in food-producing animals during maturation. Drugs administered to neonatal food-producing animals (cattle, sheep, goats, swine) may exhibit significantly different pharmacokinetic/disposition characteristics than they do in adult animals of the same species. Undesirable consequences such as suboptimum therapeutic concentrations, toxic effects, and violative tissue residues may result if adult dosage regimens are employed in young animals. Using selected drugs as examples, this paper reviews factors that contribute to differences in drug disposition in newborn vs adult animals. Immaturity of mechanisms involved in drug absorption, especially from gastrointestinal and parenteral sites of administration, and of drug distribution to sites such as plasma proteins, adipose tissue, and fluid compartments are considered. The role of developmental changes in drug biotransformation in the liver and other tissues and the maturation of excretory mechanisms, primarily from the kidney, in the increased rate of drug clearance during maturation is described. Pharmacokinetic studies with specific drugs in the target species are an important approach to establishing rational drug use in immature food-producing animals.


Pathology of soft tissue sarcomas. An introduction. Recent progress in molecular biology, cytogenetics, classification and grading of soft tissue sarcomas is briefly reviewed. It is emphasized that peer review of histopathology is highly desirable. Finally, equipped with modern imaging techniques, the radiologist can anticipate an increasing role in the aspiration cytology of deep seated soft tissue tumors.


The multidisciplinary approach to treatment of soft tissue sarcomas. Soft tissue sarcomas are rare tumors including many histological subtypes. They are pre-eminently tumors for which the multidisciplinary approach to treatment is of utmost importance. The two most frequently applied staging systems both require experienced assessment of radiology and pathology, and stage is a prominent prognostic factor for survival that guides the choice of treatment modalities. For primary treatment radical surgery is still the backbone. In many instances postoperative radiotherapy is a valuable and often necessary complementary treatment. The role of preoperative radiotherapy and/or chemotherapy needs to be defined although preliminary results are interesting. Chemotherapy as an adjunct to surgery should still be considered investigational. In metastatic disease "standard" chemotherapy has a definitive though moderate activity, but recent data on dose-intensified chemotherapy suggest that results may be further improved.


Imaging in the follow-up of soft tissue tumors. Local recurrences of aggressive soft tissue tumors are frequent and very difficult to detect clinically after surgery and radiation therapy. Ultrasound is limited because the skin is thick. On contrast-enhanced CT, both scars and recurrences increase their signal. MRI is the best technique, and the only one we presently use in the detection of recurrent tumors. We are reporting 511 follow-up examinations in 182 patients after tumor removal. All patients had histologic confirmation or at least 6 months follow-up. There were 164 malignant tumors and 18 cases of aggressive fibromatosis.


Ultrasound evaluation of soft tissue tumors. Because of its availability, ultrasound should be the preferred initial modality for the evaluation of palpable superficial masses. Most ultrasound units are equipped with high frequency probes that allow superficial focalization. The differential diagnosis of soft tissue masses and the sonographic features of some benign and malignant soft tissue lesions are reviewed in this article. After an initial ultrasound evaluation confirming the presence of a tumor, the need for and the role of other imaging modalities can be determined. In selected cases ultrasound may obviate the need for further imaging. MRI and CT should be reserved for cases in which sonography fails to establish a specific diagnosis or to demonstrate the limits of the soft tissue mass.


CT of soft tissue tumors.

CT of soft tissue tumors. We review the documented strengths and weaknesses of CT in the evaluation of soft tissue tumors and we describe what we believe to be an optimal CT technique. We also briefly outline the relation of CT to the other techniques in the diagnosis of soft tissue tumors and relate some particular CT findings to the major tumor types.


Magnetic resonance imaging of soft tissue tumors. The value of magnetic resonance imaging (MRI) in histological classification was studied in a series of 164 histologically proven soft tissue tumors (STT) and was rather limited. MRI was only valuable in characterization of lipomatous, vascular and fibrous tumors. There are two main reasons for this limitation i.e. STT belonging to the same histological group may have different composition or different proportions in tumor components resulting in different MRI signals. Secondly tumor components may change individually or proportionally during natural evolution or as a consequence of therapy. Because well known grading parameters such as cellularity, mitotic rate, matrix and presence of necrosis all influence MRI signal intensity, the value of MRI in predicting malignancy is potentially high. To assess this value we retrospectively studied the findings in the first 141 soft tissue tumors (84 benign, 57 malignant) and evaluated a wide variety of MRI features (size, margins, signal homogeneity, shape, signal intensity, neurovascular and bone involvement, degree and pattern of enhancement and evidence of necrosis after injection of Gd-DTPA). Statistical analysis was carried out to determine accuracy of parameters individually and in combination, for predicting malignancy. Highest sensitivity was obtained for "absence of low signal intensity on T2" (100%), "mean diameter > 33 mm" (90%) and "inhomogeneous signal on T1" (88%). Highest specificity was obtained for "evidence of necrosis" (98%), "bone or neurovascular involvement or metastases" (94%) and "mean diameter > 66 mm" (87%). Association of best sensitivity (81%) and specificity (81%) was seen for "absence of low signal intensity on T2", "signal inhomogeneity on T1" and "mean diameter of the lesion > 33 mm". In a prospective study of 23 consecutive patients we reevaluated sensitivity and specificity in predicting malignancy of all parameters. Excellent correlation with the results of the retrospective study was found. Although a quantitative approach to the staging potentials of MRI was not possible, well known staging parameters are evaluated to the best by this method (size, depth, compartmental versus extra-compartmental location, relationship to adjacent structures).


Reactive mesenchymal proliferation.

Reactive mesenchymal proliferation. One hundred and thirteen cases in the files of the Netherlands Committee on Bone Tumors were diagnosed as heterotopic soft tissue ossification. Myositis ossificans was diagnosed in 62, ossifying hematoma in 21, and pseudomalignant osseous tumor of soft tissues in 30 cases. Antecedent trauma was present in 37%, 46% and 7%, respectively. Myositis ossificans arose in the large muscle groups of the thighs and upper arms; when closely related to the shaft of a bone, periosteal reactions were more outspoken. Pseudomalignant osseous tumor of soft tissues was located in the hands, feet, and pelvis, some cases were not in muscle groups and some were almost periosteal. Ossifying hematoma was located in the upper and lower legs and usually in close relation to bone. The three entities belong to the same kind of reactive mesenchymal proliferative process. The radiologic and histologic patterns are reflections of whether the lesions are closely localized to bone shafts or in soft tissues, e.g. in muscles and therefore the term "reactive mesenchymal proliferation" is preferred to myositis ossificans, pseudomalignant osseous tumor of soft tissues and ossifying hematoma. Diagnostic problems are encountered in early phases when cellularity, mitotic activity, and infiltrative spread suggest malignancy. Recognition of these reactions in early phases is important to avoid mutilating surgery.


Vascular soft tissue tumors: medical imaging. Histologically, tumors of the vascular system are divided into three categories. Benign types can be localized (hemangioma) or involve large segments of the body (angiomatosis). Vascular tumors of intermediate malignancy are known as hemangioendotheliomas. Angiosarcoma is one of the rarest malignant soft tissue neoplasms. The authors present the morphological and SI features of 17 histologically proven vascular tumors (16 benign, 1 malignant) examined by MRI. The results are compared with the findings on other imaging techniques. On T1-WI, the tumors are slightly hyperintense to muscle with interspersed areas of low SI corresponding to fibrous septa, calcifications, or fastly flowing blood, and areas of SI equal to fat. On T2-WI, the lesions are more homogeneous and markedly hyperintense to fat. MRI is superior to all other imaging techniques for evaluation of extent and characterization of vascular soft tissue tumors. Angiography remains helpful in demonstrating feeding or draining vessels.


Adipose tumors of soft tissues.

Adipose tumors of soft tissues. Thirteen patients with lipoma were examined at least with MRI, which revealed homogeneous and high signal lesions in both T1 and T2 WI sequences. On CT, these lesions were characterized by very negative density values. Sonography was useful to differentiate a lipoma from an old hematoma that share the same signal on MRI. Eighteen cases of biopsy proven liposarcomas were evaluated with at least two techniques. Tumor heterogeneity was the most important clue to malignancy. With CT, contrast injection was necessary because two cases out of eight appeared homogeneous on native examinations. Lobular pattern and large size are constant signs associated with liposarcoma. The correlation of imaging and histology classification was only successful with differentiated tumors. Angiography unspecifically reveals the malignancy of liposarcoma. MRI is better than CT to evaluate tumor expansion and to differentiate the mass from the surrounding tissue.


Diagnostic imaging of muscular tumors.

Diagnostic imaging of muscular tumors. Eight patients with muscular tumors--all malignant--were reviewed. Seven patients were examined by magnetic resonance imaging. Some of them also underwent conventional radiology and computed tomography. One patient was examined by computed tomography only. An overview and short description of the muscular tumors are given. The findings with the different imaging techniques are presented, followed by a discussion of the role of the imaging techniques. The final conclusion is that MRI is the modality of choice for detection, staging, and follow-up of muscular tumors, although the signal intensity features are not always specific.


HMt, a histone-related protein from Methanobacterium thermoautotrophicum delta H. HMt, a histone-related protein, has been isolated and characterized from Methanobacterium thermoautotrophicum delta H. HMt preparations contain two polypeptides designated HMt1 and HMt2, encoded by the hmtA and hmtB genes, respectively, that have been cloned, sequenced, and expressed in Escherichia coli. HMt1 and HMt2 are predicted to contain 68 and 67 amino acid residues, respectively, and have calculated molecular masses of 7,275 and 7,141 Da, respectively. Aligning the amino acid sequences of HMt1 and HMt2 with the sequences of HMf1 and HMf2, the subunit polypeptides of HMf, a histone-related protein from the hyperthermophile Methanothermus fervidus, revealed that 40 amino acid residues (approximately 60%) are conserved in all four polypeptides. In pairwise comparisons, these four polypeptides are 66 to 84% identical. The sequences and locations of the TATA box promoter elements and ribosome binding sites are very similar upstream of the hmtA and hmtB genes in M. thermoautotrophicum and upstream of the hmfA and hmfB genes in M. fervidus. HMt binding compacted linear pUC19 DNA molecules in vitro and therefore increased their electrophoretic mobilities through agarose gels. At protein/DNA mass ratios of < 0.2:1, HMt binding caused an increase in the overall negative superhelicity of relaxed, circular DNA molecules, but at HMt/DNA mass ratios of > 0.2:1, positive supercoils were introduced into these molecules. HMt and HMf are indistinguishable in terms of their abilities to compact and constrain DNA molecules in positive toroidal supercoils in vitro. Histone-related proteins with these properties are therefore not limited to reverse gyrase-containing hyperthermophilic species.


Structure and expression of a cyanobacterial ilvC gene encoding acetohydroxyacid isomeroreductase. Acetohydroxyacid isomeroreductase (AHAIR) is the shared second enzyme in the biosynthetic pathways leading to isoleucine and valine. AHAIR is encoded by the ilvC gene in bacteria. A 1,544-bp fragment of genomic DNA containing the ilvC gene was cloned from the cyanobacterium Synechocystis sp. strain PCC 6803, and the complete nucleotide sequence was determined. The identity of the gene was established by comparison of the nucleotide and derived peptide sequences with those of other ilvC genes. The highest degree of sequence similarity was found with the ilvC gene from Rhizobium meliloti. The isolated Synechocystis ilvC gene complemented an Escherichia coli ilvC mutant lacking AHAIR activity. The expressed Synechocystis gene encodes a protein that has a molecular mass of 35.7 kDa and that has AHAIR activity in an in vitro assay. Polyclonal antibodies raised against purified Synechocystis AHAIR produced a single band on a Western blot (immunoblot) of a Synechocystis cell extract and detected the protein in an extract of an E. coli ilvC mutant strain that was transformed with a plasmid containing the Synechocystis ilvC gene. The antibody did not react with an extract of an E. coli ilvC mutant strain that was transformed with a control plasmid lacking the Synechocystis ilvC gene or with an extract of an E. coli IlvC+ control strain.


Cloning, sequencing, and high expression of the proline iminopeptidase gene from Bacillus coagulans. The gene coding for proline iminopeptidase in Bacillus coagulans was cloned and expressed in Escherichia coli. Nucleotide sequencing revealed an 861-bp open reading frame with an unusual TTG initiation codon, encoding a 287-amino-acid protein. The calculated molecular weight of the product was 32,415. The amino acid sequences of the amino-terminal region and those of some peptide fragments obtained by endoproteinase Asp-N digestion of the purified enzyme completely coincided with those deduced from the nucleotide sequence. The rare TTG initiation codon that normally codes for leucine was translated as a formal initiation codon; a methionine residue was found at the amino terminus of the enzyme. By using a vector bearing the strong tac promoter, an expression level as high as 200-fold that of the first clone was achieved. The replacement of the TTG initiation codon with ATG and a simultaneous reduction of the distance to the tac promoter resulted in a further increase of 2.5-fold. The expressed enzyme was easily purified to homogeneity by hydrophobic chromatography on a Toyopearl HW-65C column and crystallization, with a recovery of activity of 36%. The molecular weight was found to be 33,000 by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration on a Hi-Load 16/60 Superdex 200 fast protein liquid chromatography column. The expressed enzyme showed the same catalytic and physicochemical properties as those of the wild type, specifically cleaving the N-terminal proline from small substrates.


Genetic analysis of the tetA(C) gene on plasmid pBR322. The TetA(C) protein, encoded by the tetA(C) gene of plasmid pBR322, is a member of a family of membrane-bound proteins that mediate energy-dependent efflux of tetracycline from the bacterial cell. The tetA(C) gene was mutagenized with hydroxylamine, and missense mutations causing the loss of tetracycline resistance were identified at 30 distinct codons. Mutations that encoded substitutions within putative membrane-spanning alpha-helical regions were scattered throughout the gene. In contrast, mutations outside the alpha-helical regions were clustered in two cytoplasmic loops, between helices 2 and 3 and helices 10 and 11, suggesting that these regions play a critical role in the recognition of tetracycline and/or energy transduction. All of the missense mutations encoded a protein that retained the ability to rescue an Escherichia coli strain defective in potassium uptake, suggesting that the loss of tetracycline resistance was not due to an unstable TetA(C) protein or to the failure of the protein to be inserted in the membrane. We postulate that the mutations encode residues that are critical for the active efflux of tetracycline, except for mutations that result in the introduction of charged residues within hydrophobic regions of the TetA(C) protein.


Molybdoenzyme biosynthesis in Escherichia coli: in vitro activation of purified nitrate reductase from a chlB mutant. All molybdoenzyme activities are absent in chlB mutants because of their inability to synthesize molybdopterin guanine dinucleotide, which together with molybdate constitutes the molybdenum cofactor in Escherichia coli. The chlB mutants are able to synthesize molybdopterin. We have previously shown that the inactive nitrate reductase present in a chlB mutant can be activated in a process requiring protein FA and a heat-stable low-molecular-weight substance. We show here that purified nitrate reductase from the soluble fraction of a chlB mutant can be partially activated in a process that requires protein FA, GTP, and an additional protein termed factor X. It appears that the molybdopterin present in the nitrate reductase of a chlB mutant is converted to molybdopterin guanine dinucleotide during activation. The activation is absolutely dependent upon both protein FA and factor X. Factor X activity is present in chlA, chlB, chlE, and chlG mutants.


Mechanism of action of cyclic beta-1,2-glucan synthetase from Agrobacterium tumefaciens: competition between cyclization and elongation reactions. We have examined some aspects of the mechanism of cyclic beta-1,2-glucan synthetase from Agrobacterium tumefaciens (235-kDa protein, gene product of the chvB region). The enzyme produces cyclic beta-1,2-glucans containing 17 to 23 glucose residues from UDP-glucose. In the presence of added cyclic beta-1,2-glucans (> 0.5 mg/ml) (containing 17 to 23 glucose residues), the enzyme instead synthesizes larger cyclic beta-1,2-glucans containing 24 to 30 glucose residues. This is achieved by de novo synthesis and not by disproportion reactions with the added product. This is interpreted as inhibition of the specific cyclization reaction for the synthesis of cyclic beta-1,2-glucans containing 17 to 23 glucose residues but with no concomitant effect on the elongation (polymerization) reaction. Temperature and detergents both affect the distribution of sizes of cyclic beta-1,2-glucans, but glucans containing 24 to 30 glucose residues are not produced. We suggest that the size distribution of cyclic beta-1,2-glucan products depends on competing elongation and cyclization reactions.


A new nylon oligomer degradation gene (nylC) on plasmid pOAD2 from a Flavobacterium sp. Flavobacterium sp. strain KI725 harbors plasmid pOAD21, a derivative of nylon oligomer-degradative plasmid pOAD2, in which all of nylA (the gene for 6-aminohexanoate cyclic dimer hydrolase [EI]) was deleted but nylB (the gene for 6-aminohexanoate dimer hydrolase [EII]) was retained. KI725 showed no growth on unfractionated nylon oligomers (Nom1) obtained from a nylon factory as a sole carbon and nitrogen source (Nom1 minimum plate). Extracts of KI725 cells possessed hydrolytic activity for Nom1 (approximately 5% of the activity of KI72), but pOAD2-cured strains (KI722 and KI723) showed no activity. KI725R strains which grew on the Nom1 minimum plate were spontaneously isolated from KI725 at a frequency of 10(-7) per cell. Activity toward Nom1 was enhanced in KI725R strains (10 to 30% of the activity of KI72). This new Nom1 degrading enzyme (EIII, the nylC gene product) hydrolyzed not only Nom1 but also the N-carbobenzoxy-6-aminohexanoate trimer, a substrate which was not hydrolyzed by either EI or EII. Cloning and sequence analysis showed that the nylC gene is located close to nylB on pOAD21 and is a 1,065-bp open reading frame corresponding to 355 amino acid residues. The nucleotide sequence of the nylC gene and the deduced amino acid sequence of EIII had no detectable homology with the sequences of nylA (EI) and nylB (EII).


Stabilization of phosphorylated Bacillus subtilis DegU by DegR. The production of Bacillus subtilis extracellular proteases is under positive and negative regulation. The functional role of degR, one of the positive regulators, was studied in relation to the degS and degU gene products, which belong to the bacterial two-component regulatory system. Studies with a translational fusion between the Escherichia coli lacZ and the Bacillus subtilis subtilisin (aprE) genes indicated that the stimulatory site of DegR lay upstream of position -140, with the region upstream of position -200 being the major target. It was also found that degS and degU were epistatic to degR. These results suggested some relationship among the degR, degS, and degU gene products. The DegR protein was purified to homogeneity, and its in vitro effect on the phosphorylation reaction involving DegS and DegU was studied. For this purpose, a soluble-extract system in which the formation and dephosphorylation of DegU-phosphate could be examined was devised. The addition of DegR to the soluble-extract system enhanced the formation of DegU-phosphate. The enhancing effect was found to be due to the protection of DegU-phosphate from dephosphorylation. From these results, it was concluded that the positive effect of DegR on the production of the extracellular proteases is brought about by the stabilization of DegU-phosphate, which in turn may result in the stimulation of transcription of the exoprotease genes.


Participation of a cyanobacterial S layer in fine-grain mineral formation. Cyanobacteria belonging to the Synechococcus group are ubiquitous inhabitants of diverse marine and freshwater environments. Through interactions with the soluble constituents of their aqueous habitats, they inevitably affect the chemistry of the waters they inhabit. Synechococcus strain GL24 was isolated from Fayetteville Green Lake, New York, where it has a demonstrated role in the formation of calcitic minerals. In order to understand the detailed interactions which lead to mineral formation by this organism, we have undertaken detailed ultrastructural studies of its cell surface and the initial events in mineral growth using a variety of electron microscopic and computer image enhancement techniques. Synechococcus strain GL24 has a hexagonally symmetrical S layer as its outermost cell surface component. The constituent protein(s) of this structure appears as a double band by sodium dodecyl sulfate-polyacrylamide gel electrophoresis with M(r)s of 104,000 and 109,000. We demonstrate that the S layer acts as a template for fine-grain gypsum and calcite formation by providing discrete, regularly arranged nucleation sites for the critical initial events in the mineralization process. To our knowledge, this is the first time that a bacterial S layer has been shown to have a role in mineral formation in a natural environment, and this report provides conclusive evidence for the specific involvement of bacterial surfaces in natural mineral formation processes.


Interactions of Escherichia coli membrane lipoproteins with the murein sacculus. Bifunctional cross-linking reagents were used to identify cell envelope proteins that interacted with the murein sacculus. This revealed that a number of [3H]leucine-labeled proteins and [3H]palmitate-labeled lipoproteins were reproducibly cross-linked to the sacculus in plasmolyzed cells. The results suggested that most of the cell envelope lipoproteins, and not only the murein lipoprotein, mediate interactions between the murein sacculus and the inner and/or outer membrane of the cell.


Purification and characterization of the hydantoin racemase of Pseudomonas sp. strain NS671 expressed in Escherichia coli. The hydantoin racemase gene of Pseudomonas sp. strain NS671 had been cloned and expressed in Escherichia coli. Hydantoin racemase was purified from the cell extract of the E. coli strain by phenyl-Sepharose, DEAE-Sephacel, and Sephadex G-200 chromatographies. The purified enzyme had an apparent molecular mass of 32 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. By gel filtration, a molecular mass of about 190 kDa was found, suggesting that the native enzyme is a hexamer. The optimal conditions for hydantoin racemase activity were pH 9.5 and a temperature of 45 degrees C. The enzyme activity was slightly stimulated by the addition of not only Mn2+ or Co2+ but also metal-chelating agents, indicating that the enzyme is not a metalloenzyme. On the other hand, Cu2+ and Zn2+ strongly inhibited the enzyme activity. Kinetic studies showed substrate inhibition, and the Vmax values for D- and L-5-(2-methylthioethyl)hydantoin were 35.2 and 79.0 mumol/min/mg of protein, respectively. The purified enzyme did not racemize 5-isopropylhydantoin, whereas the cells of E. coli expressing the enzyme are capable of racemizing it. After incubation of the purified enzyme with 5-isopropylhydantoin, the enzyme no longer showed 5-(2-methylthioethyl)hydantoin-racemizing activity. However, in the presence of 5-(2-methylthioethyl)hydantoin, the purified enzyme racemized 5-isopropylhydantoin completely, suggesting that 5-(2-methylthioethyl)hydantoin protects the enzyme from inactivation by 5-isopropylhydratoin. Thus, we examined the protective effect of various compounds and found that divalent-sulfur-containing compounds (R-S-R' and R-SH) have this protective effect.


Cellobiose chemotaxis by the cellulolytic bacterium Cellulomonas gelida. In the course of a study on the bacterial degradation of plant cell wall polysaccharides, we observed that growing cells of motile cellulolytic bacteria accumulated, without attachment, near cellulose fibers present in the cultures. Because it seemed likely that the accumulation was due to chemotactic behavior, we investigated the chemotactic responses of one of the above-mentioned bacteria (Cellulomonas gelida ATCC 488). We studied primarily the responses toward cellobiose, which is the major product of cellulose hydrolysis by microorganisms, and toward hemicellulose hydrolysis products. We found that cellobiose, cellotriose, D-glucose, xylobiose, and D-xylose, as well as other sugars that are hemicellulose components, served as chemoattractants for C. gelida, as determined by a modification of Adler's capillary assay. Competition and inducibility experiments indicated that C. gelida possesses at least two types of separately regulated cellobiose chemoreceptors (Cb1 and cellobiose, cellotriose, xylobiose, and D-glucose, and it is constitutively synthesized. The presence in C. gelida of a constitutive response toward cellobiose and of at least two distinct cellobiose chemoreceptors has implications for the survival of this cellulolytic bacterium in nature. A possible mechanism for cellobiose-mediated bacterial chemotaxis toward cellulose is proposed. We suggest that, in natural environments, motile cellulolytic bacteria migrate toward plant materials that contain cellulose and hemicellulose by swimming up cellobiose concentration gradients and/or concentration gradients of other sugars (e.g., xylobiose, D-xylose, and D-glucose) formed by enzymatic hydrolysis of plant cell wall polysaccharides.