Differential sensitivity of the short and long human dopamine D2 receptor subtypes to protein kinase C. The human dopamine D2L (long form) and D2S (short form) receptors were expressed separately in mouse Ltk- fibroblast cells to investigate whether there is a difference in transmembrane signaling of these D2 receptors. Both receptors induced two signals, a phosphatidylinositol-linked mobilization of intracellular calcium and an inhibition of cyclic adenosine 3'-5' monophosphate (cAMP) accumulation, each with similar response magnitudes and identical pharmacology. Both calcium and cAMP signals were sensitive to pretreatment with pertussis toxin (PTX), indicating mediation by coupling to Gi/Go proteins. However, the two forms of D2 receptor were distinguished by acute prior activation of protein kinase C (PKC) with 12-O-tetradecanoyl 4 beta-phorbol 13-acetate (TPA): TPA blocked the D2S-mediated increase in cytosolic free calcium concentration ([Ca2+]i) in a concentration-dependent manner (between 10 nM and 1 microM), whereas the D2L receptor-induced increase in [Ca2+]i was resistant to TPA and was only partially (60%) inhibited by 100 microM TPA. By contrast, TPA did not alter the inhibition of cAMP accumulation induced by activation of either D2S or D2L receptors. We conclude that, in the L cell system, prior activation of PKC differentially modulates the transmembrane signaling of the D2L and D2S receptors, preferentially inhibiting the D2S receptor-mediated calcium signal but not altering the dopamine-induced inhibitory cAMP signal of either receptor subtype.


Phosphoinositide turnover associated with synaptic transmission. Although pharmacological stimulation of a wide variety of transmitter receptors triggers phosphoinositide (PI) turnover, little is known about the type of synaptic activity required to activate this system. To investigate this question, we have used primary cultures of embryonic cortical neurons, which develop functional glutamate and GABA synapses during maturation in vitro. Mature cultures display spontaneous synaptic activity that is totally suppressed by tetrodotoxin (TTX). PI turnover, assayed by the lithium-sensitive accumulation of [3H]CDP-diacylglycerol, was readily detected under basal conditions and was abolished by TTX. Increased excitatory synaptic activity induced by picrotoxin, an antagonist of GABAA receptor-mediated inhibition, further stimulated PI turnover. Similar results were obtained when PI turnover was assayed using [3H]inositol labeling. With either assay, the magnitude of synaptically induced PI turnover was comparable to maximal responses produced by muscarinic receptor stimulation. Although a component of the spontaneous synaptic currents is sensitive to N-methyl-D-aspartate (NMDA)-preferring glutamate receptor antagonists, blockade of NMDA receptors did not affect PI turnover associated with synaptic transmission. To assess the time course of synaptically mediated PI turnover, the amplitude and duration of spontaneous synaptic currents were reduced by lowering the extracellular Ca2+ concentration from 2.25 to 0.5 mM, a maneuver that suppresses basal PI turnover. Increases in PI turnover were detected as early as 5 min following restoration of the extracellular Ca2+ concentration to 2.25 mM. Taken together, these findings indicate that activation of the PI system is associated with physiological levels of glutamatergic synaptic transmission.


Antitumor agents, 130, Novel 4 beta-arylamino derivatives of 3',4'-didemethoxy-3',4'-dioxo-4-deoxypodophyllotoxin as potent inhibitors of human DNA topoisomerase II. A series of ortho-quinone analogues 1-28 of podophyllotoxin possessing various C-4 beta-aniline moieties have been synthesized and evaluated for their inhibitory activity against human DNA topoisomerase II, their activity in causing cellular protein-linked DNA breakage, and their cytotoxicity against KB cells. Compounds 8-12, 15, 19, and 23-28 are better than or comparable to etoposide in their inhibition of the human DNA topoisomerase II, while compounds 8-10 and 22 are comparable to or more potent than etoposide in causing DNA breakage. There is an apparent lack of correlation between cytotoxicity and the ability of these compounds to cause protein-linked DNA breaks or inhibit DNA topoisomerase II. This suggests that in addition to the mechanism of the topoisomerase II involving DNA breakages, other mechanisms of action, such as the radical mechanism or the direct adduct formation of the ortho-quinone with DNA or protein, may also involve and account for the apparent KB cytotoxicity. Two different modes of DNA topoisomerase II inhibition for 8-28 were proposed.


Sarcochromenol sulfates A-C and sarcohydroquinone sulfates A-C, new natural products from the sponge Sarcotragus spinulosus. New Na+,K(+)-ATPase inhibitors, sarcochromenol sulfates A [1], B [2], and C [3] and sarcohydroquinone sulfates A [4], B [5], and C [6], have been isolated from the sponge Sarcotragus spinulosus. Four of them (1, 4-6) and all six corresponding acetates 1a-6a have been isolated, and their structures have been established by spectral methods and chemical transformations.


Detection of hereditary motor sensory neuropathy type I in childhood. Clinical signs and slowed motor nerve conduction velocities were found in 17 of 36 children under 10 years of age who had one parent with hereditary motor sensory neuropathy type I (HMSN I). Four children had slowed conduction velocities at one year or less. Clinical signs were subtle and included pes planus, distal foot wasting, weakness of ankle eversion and dorsiflexion and areflexia. HMSN I can be detected reliably in children, even before one year of age.


Quantitative measures of sympathetic skin response in diabetes: relation to sudomotor and neurological function. The sympathetic skin response (SSR) at the foot to a deep inspiration was measured in 68 randomly selected diabetic patients and 46 age matched normal subjects and compared with other quantitative measures of neurological and sudomotor function. SSR was obtained in all but three diabetic patients. The upper limit of normal for the onset latency was 2202 ms and the lower limit for the amplitude of the first wave 92 microV. Ten diabetic patients had measurable but prolonged latencies, and 11 had measurable but low amplitudes. There were no significant associations between latency, height, and age, but in insulin dependent patients there was a significant diminution of response amplitude with increasing duration of diabetes. Latency was weakly associated with Marstock thermal thresholds, respiratory RR variation, and common peroneal nerve conduction velocity. SSR amplitude was associated with the density of pilocarpine activatable sweatspots in the same region of the foot. Patients with abnormal latencies were significantly older and had reduced thermal sensation than those with normal latencies. Median coefficients of variation for repeat testing in diabetic patients were 9% for latency and 13% for amplitude. The test is objective and reproducible, but latency measurements reflect conduction in a long multineuronal pathway and are not purely a measure of peripheral C fibre function; amplitude measurements reflect the density of spontaneously activable sweat glands and are therefore a valid measure of peripheral sympathetic activity, though they depend more on temperature than do latencies (mean change over the range 32-34 degrees C; 8.5% degrees C for amplitude, -2.5%/degrees C for latency).


Patterns of conduction impairment in experimental allergic neuritis. An electrophysiological and histological study. Electrophysiological and histological studies of peripheral nerve were performed in 24 Lewis rats with experimental allergic neuritis (EAN) in which disease had been induced by a single myelin and adjuvant inoculation in one footpad. Demyelination was demonstrated in transverse nerve sections from ventral roots, proximal sciatic nerves and also in distal plantar nerves. Histological and electrophysiological assessments showed that injected limbs were more affected than uninjected limbs. Neurophysiological studies demonstrated two distinct patterns of conduction failure based upon proximal/distal compound muscle action potential (CMAP) amplitude ratios in both uninjected and injected limbs. Slightly more than half of all nerve trunks showed a mildly reduced distal CMAP amplitude irrespective of stimulus origin. The rest displayed a more severe reduction of distal amplitude that was length-dependent, becoming smaller with proximal stimulation. Histological lesions in plantar nerves were often more severe than those in proximal sciatic nerves or ventral roots. Axonal degeneration was an uncommon finding. This study has demonstrated patterns of peripheral nerve conduction impairment similar to those reported in patients with inflammatory demyelinating neuropathy. Moreover, it has shown that a low distal CMAP amplitude may result from demyelination of distal motor nerve segments and not necessarily from axonal degeneration.


Internalised capillaries, neuromyopathy and myalgia. Internalised capillaries are described in the muscle fibres of two adult males who complained of exertional myalgia. In one patient, "bundles" of internalised capillaries were found in 2% of the Type 1 fibres and many of the Type 1 fibres exhibited non-specific cytoarchitectural changes. The other had hereditary motor and sensory neuropathy (HMSN) Type 2 and his muscle biopsy exhibited the more conventional single and double internalised capillaries in 3% of the muscle fibres in addition to the anticipated neuropathic changes. Electron microscopy revealed the presence of paracrystalline inclusions in the mitochondria of muscle of both patients. Dystrophin was normal on both immunogold/silver staining and immunoblotting. Sixty five of 77 recorded patients with evidence of internalisation of capillaries have been males and 10 are known to have complained of muscle cramps or severe myalgia. An ischaemic pathogenetic predisposition is proposed as a possible stimulus to the capillary internalisation, formation of paracrystalline mitochondrial inclusions and myalgia.


Oncogenes: cause or consequence in the development of glial tumors. Recent developments in the field of oncogenes and growth stimulatory factors have provided limited but essential models in neuro-oncology. The observation in gliomas of platelet growth factor (PDGF)-like immunoreactivity fits with the autocrine secretion model, rising the possibility for the growth factor independence of the cancer cells. The discovery of the tumor suppressor genes, for which loss of function mutations are oncogenic as in the RB gene of the retinoblastoma and p53 gene, has introduced a new concept of oncogenesis which could be useful even in the cure of the neoplasms. Several oncogenes are amplified and/or expressed in brain tumors, some associated with polymorphism leading to abnormal protein products. Therefore, corresponding functions, such as production of deficient epidermal growth factor receptor (EGFR) encoded by erb-B, are impaired. Abnormal chromosomal patterns have been recognized in brain tumors and found mainly in chromosomes 7 and 22 on which oncogenes erb-B and sis are located, respectively. Location of proto-oncogenes, which are normally expressed in the brain, indicate that they share common distribution patterns mainly involving the cerebellum, hippocampus and olfactory bulbs. These proto-oncogenes may be regulated by physiological and pathological events. The concept of oncogene involvement in brain tumors must be extended to include the other factors such as G-proteins, growth factor receptors, membrane-associated and cytoplasmic protein kinases, which are all responsible for the control of the cell growth and their response to external signals including chemotherapeutic drigs.


Distribution of transferrin receptors in relation to cytochrome oxidase activity in the human spinal cord, lower brainstem and cerebellum. Neuronal activity and oxidative energy metabolism are tightly coupled. There is evidence that cytochrome oxidase, the terminal enzyme of the electron transport chain, can serve as a metabolic marker of neuronal activity. All the respiratory chain enzymes have iron containing prosthetic groups and therefore represent an important component of iron utilisation. Since iron entry into cells is mediated by the transferrin receptor, this receptor may also serve as marker of neuronal activity. The histochemical distribution of cytochrome oxidase has therefore been compared with the autoradiographic distribution of the transferrin receptor in the human spinal cord, brainstem and cerebellum. Cytochrome oxidase activity showed a very similar pattern of distribution to the transferrin receptor in the spinal cord, brainstem and cerebellum. The highest levels of cytochrome oxidase activity and transferrin receptor binding were associated with; in the spinal cord, the substantia gelatinosa, laminae II and III and the motor neurones; in the medulla and pons, the spinal trigeminal nucleus, hypoglossal nucleus, dorsal motor nucleus of the vagus, inferior and superior olives, nucleus praepositus, nucleus paramedianus, central grey, superior central nuclei and locus coeruleus; in the cerebellum, the molecular layer. The results suggest that the transferrin receptor may provide a useful marker of total neuronal respiratory activity.


Beta-adrenergic system in myotonic dystrophy. Myotonic dystrophy (DM) is considered an inherited membrane disorder, but the basic defect is unknown. We studied plasma catecholamines as well as lymphocyte and muscle beta-adrenergic receptor densities and functioning in 19 DM patients and 15 control subjects. Plasma adrenaline and noradrenaline concentrations were not significantly different between DM patients and controls. In isolated lymphocytes basal cAMP production was 157 +/- 26 pmol/mg protein/10 min in DM patients and 91 +/- 12 pmol/mg protein/10 min in controls (n.s.), whereas isoproterenol-stimulated cAMP production was significantly higher in DM patients (285 +/- 42 pmol/mg protein) compared with control subjects (168 +/- 21 pmol/mg protein, P less than 0.05). Lymphocyte beta-adrenoceptor densities were similar among DM patients (50 +/- 3 fmol/mg protein) and controls (47 +/- 5 fmol/mg protein). beta-Adrenoceptor densities were also similar in muscle biopsy specimens (12.9 +/- 1 in DM and 13.1 +/- fmol/mg protein in controls). The correlation between lymphocyte and skeletal muscle receptor densities was r = 0.35 in DM patients and r = 0.22 in controls. The results do not support the hypothesis of adrenergic dysfunction in DM despite its membrane involvement.


G2-acetylcholinesterase is presynaptically localized in Torpedo electric organ. In Torpedo electric organ, much of the acetylcholinesterase (AChE) is a globular dimer (G2), anchored to the plasma membrane via covalently attached phosphatidylinositol and selectively solubilized by a bacterial phosphatidylinositol-specific phospholipase C. While the structure of this form of the enzyme is well-established, the ultrastructural localization of G2-AChE is still unclear. Selective solubilization with phosphatidylinositol-specific phospholipase C was, therefore, combined with immunocytochemistry at the electron microscope level, in order to localize G2-AChE in electric organ of Torpedo ocellata. Thin sections of electric organ were labelled with antibodies raised against Torpedo AChE, followed by gold-conjugated second antibodies, before or after exposure to the phospholipase. For comparison, the location of AChE was examined using histochemical methods. We show that (1) immunolabelling is concentrated in the synaptic clefts between nerve terminals and the innervated face of the electrocyte; (2) this labelling co-localizes with AChE histochemical reaction products; and (3) prior exposure to the phospholipase causes a decrease in AChE-associated labelling. Quantitative analysis of immunolabelling in the synaptic clefts shows that the phospholipase treatment had reduced primary labelling at or adjacent to the presynaptic membrane. Together with our earlier biochemical and immunofluorescent evidence, these results support our previous assignment of a neuronal and synaptic localization for G2-AChE in Torpedo electric organ.


The relationship between contraceptives, sexual practices, and cervical human papillomavirus infection among a college population. Four hundred and sixty-five college women were evaluated to determine if specific variables of social and sexual behavior correlated with the presence of human papillomavirus (HPV) DNA in the genital tract, and if these associations differed between women who were HPV DNA positive, HPV DNA positive/clinically (cytologically) negative, or who reported previous HPV-related disease by a history of an abnormal Papanicolaou (Pap) smear or genital warts. HPV positive women had more sexual partners in the recent past, more sexual episodes per month, and used spermacides less commonly than controls. Similarly, self-reporters were more likely to have more lifetime sexual partners and earlier age of onset for sexual activity. Cytologically negative HPV positive women were distinguished only by more sexual episodes per month and sexual partners in the past year (borderline significance). Alcohol use was significantly more frequent in all groups, underscoring this variable as a risk factor for both HPV DNA positivity and related disease in young women. Potential explanations for differences between women with clinically and non-clinically related HPV positivity are discussed, with emphasis on the need for followup studies to determine if an epidemiologically distinct subset of HPV DNA positive but clinically negative women are at risk for subsequent cervical disease.


Image-guided 1H NMR spectroscopical and histological characterization of a human brain tumor model in the nude rat; a new approach to monitor changes in tumor metabolism. In this study a human glioma-derived intracerebral tumor model was analyzed histologically and examined by image-guided 1H NMR spectroscopy. It was shown that histological characteristics such as cellular subpopulation and necrosis of the primary tumor were preserved in the implants. Usually circumscript tumor growth was present with tumor cells invading the surrounding brain parenchyma. It was demonstrated that tumor growth and tumor metabolism could be monitored by image-guided 1H NMR spectroscopy in a longitudinal study. One of the initial changes noticed was the rise of the lactate signal in the tumor region followed by an increase of the choline and a decrease of N-acetyl-aspartate and phosphocreatine signals. Even before tumor invasion in brain adjacent to the central tumor area could be demonstrated by NMR imaging increased lactate and moderately increased choline signals were measured in these regions. By histopathological examination these areas were shown to be infiltrated by single tumor cells. These observations indicate that image-guided 1H NMR spectroscopy could play an important role in the study of brain tumor biology, especially in the case of changing tumor metabolism during growth.


Treatment of malignant gliomas with surgery, intraarterial chemotherapy with ACNU and radiation therapy. Forty patients with malignant supratentorial gliomas received iterative intraarterial (IA) infusions of ACNU, 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea at a dose of 150 mg repeated every 6 weeks. Group A consisted of eighteen patients previously treated with surgery, radiation therapy (RT) and sometimes chemotherapy, who received IA ACNU at tumor recurrence. Group B consisted of twenty two patients who received IA ACNU in the postoperative pre-RT period. In group A, 8/18 patients (44%) had an objective response, including 6/12 anaplastic astrocytomas (AA) and 2/6 glioblastoma multiforme (GBM), while 10/18 patients (56%) did not respond. Median survival time was 6 months for GBM and 12 months for AA. In group B, 6/22 patients (27%) had an objective response (4/18 GBM and 2/4 AA) and 16/22 patients (73%) did not respond. Nine patients had such an extensive tumor after one or two courses of IA ACNU that RT was cancelled. Median survival time was 8 months for GBM and 8 months for AA. Three patients (8%) had ophthalmologic toxicity on the infused side. There was no case of leukoencephalopathy.


Quality of life in patients with intracranial tumors on the basis of Karnofsky's performance status. This prospective clinical trial (1983-1989) compares life-quality scores according to Karnofsky in patients with intra-cranial who had been operated upon. Karnofsky's performance status was evaluated during a follow-up period of 36 months. The patients were between 20 to 77 years of age; 132 patients had an astrocytoma grade III or IV; 42 patients with brain metastases were investigated; 72 had an astrocytoma grade I + II, and 144 had a meningioma. The median survival in patients with astrocytomas grade III or IV was 12 months; a short period with nearly normal activity (Karnofsky score 75) was followed by rapid deterioration. In patients with brain metastases, postoperatively the median functional ability reached its highest value three weeks after treatment and then decreased continuously (average score from 50-25). In patients with astrocytomas grade I and II, life-quality was reasonably good (mean score up to 75). The score was observed to increase slightly during the first year after treatment. A performance status improvement up to 80 could be obtained in patients with meningiomas; however, 35% were left unfit for work.


Neurotropic melanoma. A case report and review of the literature. Neurotropic melanoma is a rare tumor with a biphasic growth pattern associated with a change in morphology from melanocytic features toward Schwann cell features. The tumor thereby develops a capacity for infiltrating nerves which may result in clinically evident cranial neuropathies, most commonly of the fifth and seventh cranial nerves. The histology of this lesion is difficult to interpret; it often erroneously appears fibrous in origin and may be considered to be benign. Despite this benign appearance histologically, the tumor behaves aggressively with multiple local recurrences and possible CNS invasion by either direct perineural growth or distant metastases. We review the literature of neurotropic melanomas and report a 46th case which describes a typical course with neural invasion. Although a rare cause of cranial neuropathies, the neurologist should consider this entity in the differential diagnosis and the history of a recurrent skin lesion of the face should be sought whenever examining such a patient.


Phase II study of weekly intravenous menogaril in the treatment of recurrent astrocytomas in adults. Twenty patients with astrocytomas recurrent after surgery +/- radiation were treated on a phase II protocol of the new anthracycline derivative menogaril 115 mg/m2 administered intravenously once per week. Sixteen patients were evaluable for treatment efficacy. No patient achieved a major therapeutic response. Three patients (19%) had stable disease for greater than 8 weeks, including one who showed minor evidence of tumor regression, but less than 50%. Thirteen patients failed. Treatment was well tolerated. One patient developed granulocytopenia, while none developed thrombocytopenia. Four patients required an interruption in their treatment for one to two weeks because of development of granulocytopenia (one patient) or other reasons. Other toxic effects included arm vein phlebitis and skin irritation, skin discoloration of the infused arm, mild to moderate nausea and vomiting, diarrhea, stomatitis, and a fatal central venous catheter infection. Despite the fact that menogaril appeared to have therapeutic activity against recurrent astrocytomas in our phase I studies, we could not document any activity in this phase II study.


Postoperative venous thromboembolism and brain tumors: Part III. Biochemical profile. The plasminogen activator activity of 31 human brain tumor samples was assessed and the results correlated with clinical parameters and the postoperative occurrence of venous thrombosis. A significant negative correlation was found between plasminogen activator activity and venous thrombosis (P = 0.02), while positive correlations were observed between plasminogen activator activity and peritumoral brain edema (P = 0.03) and alpha 2 antiplasmin measured in the systemic circulation (P = 0.01). Tissue plasminogen activator was found in higher concentrations in meningioma tissue but did not correlate significantly with the occurrence of venous thrombosis. The results of this study suggest a local enzymatic degradation effect of plasminogen activator on thrombogenic substances present in the brain tumor and/or its environment.


Postoperative venous thromboembolism and brain tumors: Part I. Clinical profile. Forty-six patients who underwent surgery for brain tumors were studied prospectively with 125I labeled Fibrinogen leg scans to detect postoperative venous thrombosis. The incidence of thrombosis was 72% for meningioma patients, 60% for glioblastoma patients, and 20% for brain metastasis patients. Correlation between the occurrence of venous thrombosis and the various clinical factors thought to be responsible for the high incidence of thrombosis generally failed to show statistical significance. This finding, along with the marked variation in the incidence of venous thrombosis between the different brain tumor groups, strongly suggests that biological factors play a more important role than clinical factors in determining which brain tumor patient will suffer a postoperative thrombotic event.


Postoperative venous thromboembolism and brain tumors: Part II. Hemostatic profile. Preoperative hemostatic data were obtained on 42 brain tumor patients and correlated with the subsequent occurrence of venous thrombosis detected with 125I-labeled fibrinogen leg scans. The occurrence of thrombosis correlated significantly with an increased prothrombin time, plasminogen, and total fibrinolytic activity and a decreased fibrinogen level. This overall trend in the group of patients with postoperative thrombosis indicates that the hemostatic disorder noted in brain tumor patients is most closely related to a subclinical form of chronic disseminated intravascular coagulation syndrome. Differences in hemostatic parameters seen with the various types of brain tumors suggest that biological factors specific to each tumor are likely responsible for the described hemostatic disorder and support the need for further research directed at the tumor tissue level.


Preventive effects of interleukin 1 beta for ACNU-induced myelosuppression in malignant brain tumors: the experimental and preliminary clinical studies. The effect of recombinant human interleukin 1 beta (rHuIL-1 beta) on myelosuppression induced by 3-[(4-amino-2-methyl-5-pyrimidynyl)methyl]-1-(2-chloroethyl)-1-nit rosourea hydrochloride (ACNU) was studied. In in vivo study using BALB/c mice, pretreatment with 1 microgram/mouse of rHuIL-1 beta as a single intraperitoneal (i.p.) injection had a significant preventive effect on thrombocytopenia as well as granulocytopenia induced by ACNU at an intravenous dose of 60 mg/kg. Facilitated recovery by rHuIL-1 beta administered seven days after injection of high-dose ACNU was also observed. Experimental combination immunochemotherapy with high-dose ACNU and rHuIL-1 beta was performed in nude mice inoculated with human glioblastoma subcutaneously. The elongation of the survival time of the tumor bearing nude mice was also observed in combined use of high dose ACNU with rHuIL-1 beta. Seven patients with malignant brain tumors received intravenous 2.5-3 mg/kg ACNU. All patients were subcutaneously injected with 2 x 10(4)-U or more rHuIL-1 beta twice a week or daily. The mean nadir of leukocyte, granulocyte, and thrombocyte counts of the 7 patients received 2.5-3 mg/kg ACNU were significantly higher than in matched historical controls. In combination with rHuIL-1 beta, it may be possible to use chemotherapeutic agents at a relatively high dose.


In vivo CT measurement of blood-brain transfer constant of iopamidol in human brain tumors. We have developed an in vivo method of measuring the blood-brain transfer constant (K) of iopamidol and the cerebral plasma volume (Vp) in brain tumors using a clinical X-ray CT scanner. In patient studies, Isovue 300 (iopamidol) was injected at a dosage of 1 ml/kg patient body weight. Serial CT scans of the tumor site and arterial blood samples from a radial artery were taken up to 48 min after injection. The leakage of iopamidol into the brain through the blood-brain barrier was modelled as an exchange process between two compartments, the intravascular plasma space and the tissue interstitial space. Using this model and the concentration measurements in blood plasma and tissue, quantitative estimates of K and Vp in brain tumors were obtained. In addition, distribution of the estimated values of K and Vp in tumors were displayed as false colour functional images overlaid on the conventional CT scan. In a study of twelve patients with anaplastic astrocytoma (n = 3), glioblastoma multiforme (n = 4) or metastases (n = 5) the mean K and Vp values in tumor were found to be 0.0273 +/- 0.0060 ml/min/g and 0.068 +/- 0.11 ml/g respectively. These values were significantly higher than those in grey or white matter in the contralateral 'normal' hemisphere (p less than 0.05). The functional images showed variations in K and Vp within the tumor which were difficult to perceive in the original contrast enhanced CT scans.


p53 gene mutations in primary lung tumors are conserved in brain metastases. The p53 product is frequently mutated in human tumors. Both acquired and inherited mutations have been described. These mutations transform p53 from a growth suppressor gene to a transforming oncogene. We examined tissue from 6 patients with primary lung carcinoma and the corresponding brain metastases for the presence of p53 mutations by immunohistochemistry. We then confirmed and characterized the mutations by single strand conformation analysis and by direct sequence analysis. All 6 patients had primary and metastatic tumor expressing a mutant p53. The mutations were all G-T transversions and mapped to exons 5, 6, 7, and 8. The mutations in the primary tumors were precisely conserved in the brain metastases.


Onset of a painful peripheral neuropathy in rat: a partial and differential deafferentation and spontaneous discharge in A beta and A delta primary afferent neurons. 1. The activity of primary afferent axons was recorded in rats that had received a chronic constriction injury (CCI) to the common sciatic nerve. The CCI gives rise to a painful peripheral neuropathy that is characterized by allodynia, hyperalgesia, and, probably, spontaneous pain (or dysesthesia). In the majority of animals, these neuropathic pain symptoms begin 2 days postinjury; sciatic nerve afferents were examined just before and just after the time of symptom onset, at 1 and 3 days postinjury. 2. We used two stimulating electrodes, one proximal to the injury and the other distal, to activate the injured sciatic nerve while we recorded from individual primary afferent axons in microfilaments teased from the L4-L6 dorsal roots. Measurements of conduction velocities (calculated from the proximal electrode) and evaluation of conduction through the site of injury were made from 181 A beta, 135 A delta, and 60 C-fibers. 3. The percentage of axons that did not conduct through the injury site at 1 day postinjury was 85% for the A beta fibers and 55% for the A delta fibers, but only 9% for the C-fibers. By day 3, these percentages had increased to 89% for the A beta fibers, 87% for the A delta fibers, and 32% for the C-fibers. Some axons were activated from the distal stimulating electrode at currents greater than 5-10 times those required from the proximal electrodes, but their distally evoked responses did not have the longer latencies expected from a more distant site of activation. Control experiments confirmed that such high-threshold responses were due to current spread from the distal electrode to a site proximal to the nerve injury. 4. Spontaneous discharges were observed in 35% of A beta fibers, 15% of A delta fibers, and 3% of C-fibers (data from 1 and 3 days postinjury combined). Of the 55 A beta fibers exhibiting spontaneous discharge, 89% did not conduct through the injury site; the same was true of 65% of the A delta fibers (n = 20). Both of the two spontaneously discharging C-fibers conducted through the injury. The frequency of the spontaneous discharge of the myelinated fibers ranged from 10 to 50 Hz and was usually regular or bursting. 5. Intravenous administration of gallamine triethiodide (Flaxedil), a K+ channel blocker, either induced activity in previously silent fibers or increased the frequency of spontaneous activity in 50% (21/42) of A beta fibers and 19% (3/16) of A delta fibers.(ABSTRACT TRUNCATED AT 400 WORDS)


Contribution of Ca and Ca-activated Cl channels to regenerative depolarization and membrane bistability of cone photoreceptors. 1. Cone photoreceptors in several vertebrate species generate Ca-dependent regenerative depolarizations (e.g., Ca spikes lasting up to 2 s) in response to current injection or surround illumination and may remain in a state of prolonged depolarization (e.g., a permanent plateau near 0 mV) after these stimuli. This paper, while confirming the role of Ca channels in the regenerative depolarization, demonstrates that Ca-activated Cl channels either enhance or hinder prolonged depolarization, depending on the value of the chloride equilibrium potential (ECl). 2. Current- and voltage-clamp recordings obtained with the whole-cell patch-clamp technique were compared in 158 isolated tiger salamander cones to determine the contribution of specific ion channel types to the two forms of depolarizing response. Cones dialyzed with CsCl or KCl intracellular solution (such that ECl = 0 mV) that had sustained negative slope regions in their current-voltage (I-V) relations recorded under voltage clamp, were, under current clamp, bistable with respect to their resting potential. Injection of approximately 20-pA steps of depolarizing current resulted in transitions from the negative stable membrane potential (near -50 mV) to a long lasting plateau around 0 mV. Injection of 200-300 pA of hyperpolarizing current could then force a return to the negative stable resting potential, although once repolarization occurred, current injection had to be reduced or terminated to prevent damaging hyperpolarization of the cell. 3. The inward currents accounting for the negative slope region of the I-V relation were carried in Ca and Ca-activated Cl channels. Specific block of Ca-activated Cl current (ICl(Ca)) by 100 microM niflumic acid (NFA) eliminated the prolonged depolarization, even though the negative slope conductance region in the I-V persisted and the cone could still produce the briefer Ca-dependent regenerative depolarizations. Application of 100 microM Cd2+ blocked both forms of depolarization. 4. Substitution of Ba2+, which among other actions did not activate ICl(Ca), usually supported regenerative depolarizations of shortened duration, demonstrating the role of Ca channels in the initial phase of these responses. 5. A difference was observed in the regenerative depolarization when ECl was shifted away from 0 mV, where it had been in the experiments described above. With ECl set to -40 or -60 mV by reduction of [Cl-] in the pipette, steady-state membrane bistability was eliminated and prolonged depolarization did not occur. Under these conditions, application of the Cl channel blocker NFA showed that ICl(Ca) contributes to membrane hyperpolarization.(ABSTRACT TRUNCATED AT 400 WORDS)


Ion channels in spinal cord astrocytes in vitro. II. Biophysical and pharmacological analysis of two Na+ current types. 1. Na+ currents expressed in astrocytes cultured from spinal cord were studied by whole cell patch-clamp recording. Two subtypes of astrocytes, pancake and stellate cells, were morphologically differentiated and showed expression of Na+ channels at densities that are unusually high for glial cells (2-8 channels/microns2) and comparable to cultured neurons. 2. Na+ currents in stellate and pancake astrocytes were comparable to neuronal Na+ currents with regard to Na(+)-current activation (tau m) and inactivation (tau h) time constants, which were equally fast in both astrocyte types. However, they differed with respect to voltage dependence of activation, and current-voltage (I-V) curves were approximately 10 mV more positive in stellate cells (-11.1 +/- 5.6 mV, mean +/- SD) than in pancake cells (19.7 +/- 4.5 mV). Steady-state activation (m infinity curves) was 16 mV more negative in pancake (mean V1/2 = -48.8 mV) than in stellate cells (mean V1/2 = -32.7 mV). 3. Steady-state inactivation (h infinity curves) of Na+ currents was distinctly different in the two astrocyte types. In stellate astrocytes h infinity curves had midpoints close to -65 mV (-64.6 +/- 6.5 mV), similar to most cultured neurons. In pancake astrocytes h infinity-curves were approximately 25 mV more negative, with midpoints close to -85 mV (84.5 +/- 9.5 mV). 4. The two forms of Na+ currents were additionally distinguishable by their sensitivity to tetrodotoxin (TTX). Na+ currents in stellate astrocytes were highly TTX sensitive [half-maximal inhibition (Kd) = 5.7 nM] whereas Na+ currents in pancake astrocytes were relatively TTX resistant, requiring 100- to 1,000-fold higher concentrations for blockage (Kd = 1,007 nM). 5. Na+ currents were fit by the Hodgkin-Huxley (HH) model. In pancake astrocytes, as in squid gigant axons, Na(+)-current kinetics could be well described with an m3h model, whereas in stellate astrocytes Na+ currents were better described with higher-order power terms for activation (m). On average, best fits were obtained using an m4h model. 6. Pancake astrocytes were capable of generating action-potential (AP)-like responses under current clamp whereas stellate astrocytes were not. The h infinity curve for APs shows that membrane potentials more negative than -70 mV are required to allow these responses to occur.(ABSTRACT TRUNCATED AT 400 WORDS)


A model of the electrophysiological properties of thalamocortical relay neurons. 1. A model of the electrophysiological properties of single thalamocortical relay neurons in the rodent and cat dorsal lateral geniculate nucleus was constructed, based in part on the voltage dependence and kinetics of ionic currents detailed with voltage-clamp techniques. The model made the simplifying assumption of a single uniform compartment and incorporated a fast and transient Na+ current, INa; a persistent, depolarization-activated Na+ current, INap; a low-threshold Ca2+ current, I(T); a high-threshold Ca2+ current, IL; a Ca(2+)-activated K+ current, IC; a transient and depolarization-activated K+ current, IA; a slowly inactivating and depolarization-activated K+ current, IK2; a hyperpolarization-activated cation current, Ih; and K+ and Na+ leak currents IKleak and INaleak. 2. The effects of the various ionic currents on the electrophysiological properties of thalamocortical relay neurons were initially investigated through examining the effect of each current individually on passive membrane responses. The two leak currents, IKleak and INaleak, determined in large part the resting membrane potential and the apparent input resistance of the model neuron. Addition of IA resulted in a delay in the response of the model cell to a depolarizing current pulse, whereas addition of IK2, or IL combined with IC, resulted in a marked and prolonged decrease in the response to depolarization. Addition of Ih resulted in a depolarizing "sag" in response to hyperpolarization, whereas addition of IT resulted in a large rebound Ca2+ spike after hyperpolarization. Finally, addition of INap resulted in enhancement of depolarization. 3. The low-threshold Ca2+ spike of rodent neurons was successfully modeled with the active currents I(T), IL, IA, IC, and IK2. The low-threshold Ca2+ current I(T) generated the low-threshold Ca2+ spike. The transient K+ current IA slowed the rate of rise and reduced the peak amplitude of the low-threshold Ca2+ spike, whereas the slowly inactivating K+ current IK2 contributed greatly to the repolarization of the Ca2+ spike. Activation of IL during the peak of the Ca2+ spike led to activation of IC, which also contributed to the repolarization of the Ca2+ spike. Reduction of any one of the K+ currents resulted in an increase in the other two, thereby resulting in substantially smaller changes in the Ca2+ spike than would be expected on the basis of the amplitude of each ionic current alone.(ABSTRACT TRUNCATED AT 400 WORDS)


Quantal synaptic transmission in phrenic motor nucleus. 1. The quantal nature of excitatory synaptic transmission was studied in respiratory interneurons and phrenic motoneurons of intact neonatal rat brain stem-spinal cord preparations in vitro. Synaptic currents were recorded with whole-cell patch-clamp recording techniques. 2. Because the most important factor for quantal detection is the ratio of quantal size to quantal standard deviation, factors that influence this ratio were evaluated so that experimental techniques that enhance this ratio could be defined. 3. Under favorable conditions, we directly observed quantal amplitude fluctuations in spontaneous excitatory postsynaptic currents (EPSCs) in spinal cord respiratory neurons. The quantal conductance size was 55-100 pS. With fast decay of these EPSCs, the charge reaching the soma for a single quantum is only approximately 15 fC (Vh = -80 mV). 4. We also studied miniature EPSC amplitude distributions. These were skewed, as previously reported; however, distinct quantal intervals were observed. Furthermore, in three cells tested, the quantal size in the miniature EPSC amplitude distribution was similar to the quantal size in the spontaneous EPSC amplitude distribution. 5. We conclude that excitatory synaptic transmission in the mammalian spinal cord is quantal and that the apparent skewness of miniature EPSC distributions results from summation of events with multiple quantal peak amplitudes.


Ion channels in spinal cord astrocytes in vitro. I. Transient expression of high levels of Na+ and K+ channels. 1. Na+ and K+ channel expression was studied in cultured astrocytes derived from P--0 rat spinal cord using whole cell patch-clamp recording techniques. Two subtypes of astrocytes, pancake and stellate, were differentiated morphologically. Both astrocyte types showed Na+ channels and up to three forms of K+ channels at certain stages of in vitro development. 2. Both astrocyte types showed pronounced K+ currents immediately after plating. Stellate but not pancake astrocytes additionally showed tetrodotoxin (TTX)-sensitive inward Na+ currents, which displayed properties similar to neuronal Na+ currents. 3. Within 4-5 days in vitro (DIV), pancake astrocytes lost K(+)-current expression almost completely, but acquired Na+ currents in high densities (estimated channel density approximately 2-8 channels/microns2). Na+ channel expression in these astrocytes is approximately 10- to 100-fold higher than previously reported for glial cells. Concomitant with the loss of K+ channels, pancake astrocytes showed significantly depolarized membrane potentials (-28.1 +/- 15.4 mV, mean +/- SD), compared with stellate astrocytes (-62.5 +/- 11.9 mV, mean +/- SD). 4. Pancake astrocytes were capable of generating action-potential (AP)-like responses under current clamp, when clamp potential was more negative than resting potential. Both depolarizing and hyperpolarizing current injections elicited overshooting responses, provided that cells were current clamped to membrane potentials more negative than -70 mV. Anode-break spikes were evoked by large hyperpolarizations (less than -150 mV). AP-like responses in these hyperpolarized astrocytes showed a time course similar to neuronal APs under conditions of low K+ conductance. 5. In stellate astrocytes, AP-like responses were not observed, because the K+ conductance always exceeded Na+ conductance by at least a factor of 3. Thus stellate spinal cord astrocyte membranes are stabilized close to EK as previously reported for hippocampal astrocytes. 6. It is concluded that spinal cord pancake astrocytes are capable of synthesizing Na+ channels at densities that can, under some conditions, support electrogenesis. In vivo, however, AP-like responses are unlikely to occur because the cells' resting potential is too depolarized to allow current activation. Thus the absence of electrogenesis in astrocytes may be explained by two mechanisms: 1) a low Na-to-K conductance ratio, as in stellate spinal cord astrocytes and in other previously studied astrocyte preparations; or, 2) as described in detail in the companion paper, a mismatch between the h infinity curve and resting potential, which results in Na+ current inactivation in spinal cord pancake astrocytes.


The distribution of thirteen GABAA receptor subunit mRNAs in the rat brain. III. Embryonic and postnatal development. The embryonic and postnatal expression of 13 GABAA receptor subunit genes in the rat CNS was studied by in situ hybridization. Each transcript exhibited a unique regional and temporal developmental expression profile. For example, in both embryonic and early postnatal cortex and thalamus, expression of the alpha 2, alpha 3, alpha 5, and beta 3 mRNAs was pronounced. In particular, the alpha 5 gene expression underwent a prominent peak in early brain. Subsequently, the thalamocortical expression of these four genes substantially diminished and was superseded in the adult by the alpha 1, alpha 4, beta 2, and delta subunit mRNAs. Similarly, gamma 1 and gamma 3 gene expression also dropped markedly during development, their initial stronger expression being restricted to relatively few structures. In contrast, gamma 2 gene expression was widespread and mostly remained constant with increasing age. The medial septum and globus pallidus were regions expressing few subunits in both early postnatal and adult stages, allowing clear developmental combinatorial changes to be inferred (alpha 2/alpha 3 beta 2 gamma 2 to alpha 1 beta 2 gamma 2, alpha 2/alpha 3 beta 2 gamma 1 to alpha 1 beta 2 gamma 1/gamma 2, respectively). In contrast, cerebellar Purkinje cells exhibited no developmental switch, expressing only the alpha 1, beta 2, beta 3, and gamma 2 mRNAs from birth to adult. Certain GABAA transcripts were also detected in germinal zones (e.g., beta 1, beta 3, gamma 1) and in embryonic peripheral tissues such as dorsal root ganglia (e.g., alpha 2, alpha 3, beta 3, gamma 2) and intestine (gamma 3). Some parallels in regional and temporal CNS expression were noted (e.g., alpha 1 beta 2, alpha 2 beta 3, alpha 4/alpha 6 delta), whereas the alpha 5 and beta 1 regional mRNA expressions converted over time. The changes of GABAA receptor subunit gene expression suggest a molecular explanation for earlier observations on changing ligand binding affinities. Thus, the composition, and presumably properties, of embryonic/early postnatal rat GABAA receptors differs markedly from those expressed in the adult brain.


Light-evoked expansion of subretinal space volume in the retina of the frog. The retina of the frog was superfused with a Ringer solution containing impermeant "probe" cations and anions. Light-evoked concentration changes in these probe ions were measured in the subretinal space (SRS) with ion-selective microelectrodes. A decrease in probe ion concentration was found, and several observations suggest that this is caused by a light-evoked expansion of the SRS. The probe ion decrease was not seen in the isolated retina; thus, the pigment epithelial (PE) cells are important for its generation. Pharmacological studies suggest that K+ channels in the PE cells are important--perhaps the PE cells shrink in response to the light-evoked decrease in SRS [K+]. The light-evoked decrease of SRS volume may be important in the understanding of SRS solute concentrations, retina-PE adhesivity, photoreceptor-PE cell interactions, and the interphotoreceptor matrix.


Pharmacological and immunocytochemical characterization of metabotropic glutamate receptors in cultured Purkinje cells. Metabotropic glutamate receptor (mGluR) is highly expressed in cerebellar Purkinje cells. The purpose of this study was pharmacological and immunocytochemical characterization of the mGluR in single cerebellar neurons, especially Purkinje cells. Ca2+ imaging with fura-2 in cultured cerebellar neurons, identified immunocytochemically, was used to record the direct effects of drugs in stable conditions. In addition, the expression of mGluR was examined, and expression of the intracellular receptor for inositol trisphosphate (IP3) produced by mGluR activation was studied immunocytochemically with specific antibodies. Purkinje neurons and some other neurons showed Ca(2+)-mobilizing responses to mGluR agonists. These responses were mediated by mGluR because they were not blocked by ionotropic GluR antagonists, were independent of the caffeine-sensitive Ca2+ pool, and were blocked by inhibitors of IP3-induced Ca2+ release. This is the first pharmacological characterization of mGluR at single Purkinje cells. The results differed as follows from those in earlier studies in which phosphoinositide turnover of the entire population of cerebellar cells was monitored: (1) the mGluR responses were not blocked by pertussis toxin or D,L-2-amino-3-phosphonopropionic acid; (2) glutamate was a potent agonist, whereas L-aspartate was ineffective; and (3) the dose-response relationship showed an all-or-none tendency. The metaboltropic response of Purkinje cells changed markedly during development, with a sharp peak after day 4 of culture, whereas mGluR and IP3 receptor proteins increased steadily during maturation. This apparent desensitization of mGluR was not blocked by inhibitors of protein kinase C (PKC) or ADP-ribosyltransferase. The metabotropic responses were mainly localized to the center of the somata of Purkinje cells even on day 4, whereas both receptor proteins were expressed throughout the cell. These results suggest that the function of mGluR is spatially and developmentally controlled by a posttranslational mechanism involving a mechanism other than phosphorylation by PKC or ADP-ribosylation.


Equipotentiality of thalamo-amygdala and thalamo-cortico-amygdala circuits in auditory fear conditioning. The goal of the present study was to examine the contribution of thalamo-amygdala and thalamo-cortico-amygdala projections to fear conditioning. Lesions were used to destroy either the thalamo-cortico-amygdala projection, the thalamo-amygdala projection, or both projections, and the effects of such lesions on the acquisition of conditioned fear responses (changes in arterial pressure and freezing behavior) to a tone paired with footshock were measured. In each group of animals examined, a large lesion of the acoustic thalamus, including all nuclei of the medial geniculate body and adjacent portions of the posterior thalamus, was made on one side of the brain to block auditory transmission to the forebrain at the level of the thalamus on that side. In this way, experimental lesions could be made on the contralateral side of the brain. Thus, animals with thalamo-amygdala pathway lesions received a large lesion of the acoustic thalamus on one side. Contralaterally, only the nuclei that project to the amygdala (the medial division of the medial geniculate body, the posterior intralaminar nucleus, and the suprageniculate nucleus) were selectively destroyed, leaving much of the thalamo-cortico-amygdala projection intact. For thalamo-cortico-amygdala pathway lesions, the acoustic thalamus was destroyed on one side and temporal and perirhinal cortices were ablated contralaterally. In these animals, thalamo-amygdala projections were intact on the side of the cortical lesion. Destruction of either pathway alone had no effect on auditory fear conditioning. However, combined lesions of the two sensory pathways disrupted conditioning.(ABSTRACT TRUNCATED AT 250 WORDS)


Nicotinic acetylcholine receptor desensitization is regulated by activation-induced extracellular adenosine accumulation. Adenosine modulation of nicotinic ACh receptor (nAChR) function was studied in primary cultures of rat skeletal muscle. Activation of the nAChR by carbachol increased extracellular adenosine concentration in a dose-dependent manner. Furthermore, carbachol activation of the nicotinic receptor resulted in a twofold increase in cAMP levels in the muscle cells. The carbachol-dependent increase in cAMP levels was inhibited by adenosine receptor antagonists as well as by nicotinic receptor antagonists. These results suggest that the increased cAMP levels were due to adenosine receptor activation by the extracellular adenosine accumulated on nAChR activation. Others have shown that desensitization of the nAChR by agonist is mediated, in part, by phosphorylation. Since we found that nicotinic cholinergic agonists also cause adenosine accumulation with concomitant cAMP increases, we determined whether the accumulated adenosine has a role in desensitization. We found that the adenosine receptor antagonist, BW1434U, significantly inhibited carbachol-induced nAChR desensitization, indicating that extracellular adenosine is involved in nAChR desensitization. Our data suggest that nAChR function is regulated via a feedback mechanism mediated by adenosine released from muscle on activation of the nAChR.


Patterns of inter- and intralaminar GABAergic connections distinguish striate (V1) and extrastriate (V2, V4) visual cortices and their functionally specialized subdivisions in the rhesus monkey. Local GABAergic connections are undoubtedly important for the operation of cerebral cortex, including the tuning of receptive field properties of visual cortical neurons. In order to begin to correlate specific configurations of GABAergic networks with particular receptive field properties, we examined the arrangement of GABAergic neurons projecting to foci in compartments of known functional specialization in striate (area V1) and extrastriate (areas V2, V4) cortices of rhesus monkeys. GABAergic cells were detected autoradiographically following microinjections into supragranular, granular, or infragranular layers of 5, 10, or 50 nl of 3H-nipecotic acid, which selectively exploits the GABA reuptake mechanism. These injections produced complex inter- and intralaminar distributions of retrograde perikaryal labeling that was selective for GABA-immunopositive neurons and glia. The pattern of retrograde labeling depended on both the laminar and cytoarchitectonic location of injection sites. In all cases, a high density of labeled neurons was present in the immediate vicinity of injection sites, with the density of labeled neurons decreasing for the most part uniformly with horizontal distance. Injections in supragranular layers produced relatively widespread labeling (up to 1.5-1.7 mm from the center of injections) in upper layers, whereas in granular and infragranular layers, labeling was confined to a radius of 0.25-0.5 mm. Conversely, injections in infragranular layers produced labeling that was widest (up to 1 mm) in lower layers, but more laterally restricted in supragranular layers. Injections in granular layers, on the other hand, produced an even distribution of labeling, 0.6-1.0 mm in diameter, throughout all layers. Comparably placed injections in V1, V2, and V4 resulted in patterns of labeling that were distinguished by features including stepwise increases in the lateral extent of labeling from striate to extrastriate areas, and the circular versus markedly elongated intralaminar distribution of labeled neurons in V1 and V4 versus V2. Further, for superficial injections, labeling was present in all layers in V1 and V2, but did not extent below the top layer V in area V4. These findings offer clear examples of organizational differences in the intrinsic inhibitory connections of visual cortices. The results also demonstrate that the number of GABAergic neurons projecting to any spot in cortex decreases systematically with horizontal distance from the spot, and that radiolabeled cells do not coalesce to form slabs, columns, or clusters. This relatively even distribution of retrogradely labeled cells in the tangential plane is consistent with recent computer simulations (Worgotter and Koch, 1991) that suggest that inhibitory neurons broadly tuned as a population can produce the specific response properties of cortical neurons.(ABSTRACT TRUNCATED AT 400 WORDS)


Tenosynovial giant-cell tumor of the cervical spine. Case report. A case of tenosynovial giant-cell tumor affecting the cervical spine is reported. The lesion is seen primarily in the fingers, knee, or ankle, and there are no previous reports of it occurring in the spine. The histological and radiological features of this tumor are discussed along with a brief description of the disease entity.


Legal and ethical issues in HIV testing, Part 2. In part 1 of this two-part series, legal and ethical issues in HIV testing were examined, such as the ELISA test, informed consent, confidentiality, and mandatory vs. voluntary testing. In this article, the author presents the most important legal and ethical concerns related to legislation for testing, testing in the workplace, Centers for Disease Control guidelines and recommendations, ethical analysis, and implications for nurse executives.


The level and focus of geriatric nursing content in ADN and BSN programs. The didactic and clinical focus of geriatric curriculum content within both associate (ADN) and baccalaureate (BSN) schools of nursing in California was reviewed. Geriatric nursing content experts confirmed the detail of a geriatric nursing curriculum, then determined which of the content items were basic to both educational levels, and which might be appropriately deferred to programs of baccalaureate preparation. Nurse educators may use the results of this study to guide curriculum development in both depth and breadth of content.


Degree of comfort in providing care to PWAs: effect of a workshop for baccalaureate nursing students. A low-incidence area of HIV/AIDS was the site for this study, which examined baccalaureate nursing students' degree of comfort in providing basic nursing care to people with AIDS (PWAs), and determined the effect of a National Institutes of Health (NIH)-sponsored one-day workshop on HIV/AIDS on this degree of comfort. The pretest-posttest study revealed no statistically significant decrease after the workshop in the amount of discomfort associated with providing basic nursing care to PWAs. However, there were changes in the ranking of nursing procedures following the workshop. Included is a discussion of the workshop's effect on students' comfort level and implications for nurse educators. Ideas for related studies in the area of HIV health care are explored.


The odds for success on NCLEX-RN by nurse candidates from a four-year baccalaureate nursing program. First-time nurse candidates from a four-year baccalaureate nursing program were examined to identify predictors of success on NCLEX-RN. Five logistic regression models were tested to see if specific variables increased nurse candidates' odds for success or failure. The use of admission criteria was the poorest model in predicting performance. Cumulative grade point averages (GPAs) suggested that the end of the sophomore year was the best time for predicting success and the end of the junior year was best for predicting failure. Age was inversely related to successful performance in three of the five models. Using cumulative nursing GPAs, the likelihood of predicting success on NCLEX-RN increased at the end of each academic year.


Nursing education in the United States, 1898-1910: a time of auspicious beginnings. Nursing education in the United States has been and continues to be a slowly evolving process. For those involved in nursing education at the end of the 20th century, a brief trip back to the end of the 19th century--to chronicle some of the events of that time that have had an impact on nursing education today, and to review some of the accomplishments of our early nursing educators--makes for an interesting journey.


Thermogenic capacity of brown adipose tissue is reduced in rats fed a high protein, carbohydrate-free diet. The functional state of interscapular brown adipose tissue (IBAT) was examined in rats fed for 20-30 d a high protein, carbohydrate-free diet [70% (wt/wt) protein, 8% fat] or a balanced diet (66% carbohydrate, 17% protein, 8% fat). In rats fed the high protein diet, body weight did not differ from that of control rats, but relative IBAT weight (grams per 100 g body wt) and lipid concentration (per gram of tissue) were 37% and 14% lower, respectively. In vivo rates of lipogenesis in IBAT, epididymal and retroperitoneal adipose tissue of rats fed the high protein diet were 20, 30 and 40%, respectively, of control values. Mitochondrial protein and cytochrome oxidase activity per total IBAT were significantly lower in rats fed the high protein diet than in controls; GDP binding was lower even when expressed per total tissue or per milligram of mitochondrial protein. The increase of IBAT temperature following norepinephrine infusion was significantly smaller than in controls. It is suggested that the decrease in IBAT capacity in the rats fed the high protein diet was due, at least in part, to a sustained reduction of sympathetic activity.


Selenium deficiency alters the lipoxygenase pathway and mitogenic response in bovine lymphocytes. We investigated the effect of altered selenium (Se) nutrition on arachidonic acid oxidation in immune cells. Experiments were conducted with peripheral blood lymphocytes obtained from dairy cattle fed diets either supplemented with or deficient in Se. The results indicate that the concanavalin A-stimulated lymphocyte proliferation was significantly lower in Se-deficient cows. When stimulated by calcium ionophore A23187, the lymphocytes derived from Se-deficient cows produced significantly less 5-hydroxyeicosatetraenoic acid (5-HETE) and leukotriene B4 (LTB4) than those obtained from Se-supplemented cows. When included in cell cultures from animals fed +Se diets, 5-HETE and LTB4 elicited a partial reversal of the inhibition of lymphocyte proliferation by either hydrocortisone or nordihydroguaiaretic acid. Based on this information, we postulate that dietary Se status, which in turn determines tissue Se concentration, plays an important role in the regulation of arachidonate metabolism by way of the 5-lipoxygenase pathway. This may be one of the biochemical mechanisms underlying the inhibition of lymphocyte proliferation and the decrease in resistance to infectious diseases observed in Se-deficient animals.


Simulation of nutrient digestion, absorption and outflow in the rumen: model description. A mathematical model is described that stimulates the digestion, absorption and outflow of nutrients in the rumen. The model consists of 17 state variables, representing nitrogen, carbohydrate, lipid, microbial and volatile fatty acid pools. The flux equations are described by Michaelis-Menten or mass action forms with parameters calculated from the literature. Several specific areas of improvement in representation of rumen processes were reconsidered during model development. These included microbial substrate preference, differential outflow and chemical composition of rumen microbes, recycling of microbial matter within the rumen, uncoupling of fermentation with respect to nitrogen availability, reduced microbial activity at reduced rumen pH and pH-dependent absorption of volatile fatty acids and ammonia. The model was used to examine the effects of the diet on the profile of nutrients available for absorption and was shown to respond appropriately to different intake and nitrogen levels. The validity of the improvements and the predictions of nutrient supply on a variety of dietary inputs are tested in a companion paper.


Simulation of nutrient digestion, absorption and outflow in the rumen: model evaluation. A mathematical model of the rumen fermentation processes constructed to predict nutrient supply to the host animal was evaluated. Sensitivity analysis on high fiber, starch and protein diets indicated that the model responds appropriately to these types of diets and to changes in parameter values, and revealed that the model is sensitive to the availability of hexose for non-growth microbial processes and to the maximum storage rate of polysaccharides in amylolytic microbes, although sensitivity varied with diet composition. Of the parameters whose values were dependent on diet, the fraction of protozoa in the amylolytic microbial pool and the fluid and solid passage rates needed the most careful estimation. When model predictions of nutrient supply were compared with the experimental observations, those for duodenal flows of neutral detergent fiber, total non-ammonia nitrogen (NAN) and total volatile fatty acid rumen concentration were satisfactory for several feeding strategies. The partition of NAN flow into microbial and non-microbial NAN flow and the molar proportions of volatile fatty acid production and concentration were not predicted well. The representation of the complex interactions between rumen microbial populations and of their effects on the production of specific volatile fatty acids merits further study for an improvement in the prediction of nutrient supply.


Barley beta-glucans alter intestinal viscosity and reduce plasma cholesterol concentrations in chicks. Ninety-six 14-d-old male broiler chicks were divided into three dietary groups and fed a corn-soybean meal diet, a barley diet with beta-glucanase and that diet without beta-glucanase. All diets contained 4 g cholesterol/kg. Average daily body weight gain, plasma total cholesterol concentration, LDL cholesterol concentration and digestibility of lipids and protein were lowest (P < 0.05) in the chicks fed the barley diet without beta-glucanase and highest (P < 0.05) in the chicks fed corn-soybean meal diet. Supplementation of the barley diet with beta-glucanase resulted in greater (P < 0.05) average daily weight gain, plasma total and LDL cholesterol concentrations and digestibility of lipids. Viscosity of small intestinal digesta was greatest in chicks fed barley, lowest in those fed the corn-soybean diet and intermediate in chicks fed enzyme-treated barley. Significant (P < 0.01) negative correlations occurred between viscosity of the small intestinal contents and average daily weight gain, plasma total and LDL cholesterol concentrations, and digestibility of lipids and protein. A lower concentration of insoluble beta-glucans in small intestinal digesta of the chicks fed barley supplemented with beta-glucanase compared with the chicks fed the unsupplemented barley diet reflects hydrolytic activity of the supplemental beta-glucanase in the diet.


Characterization of inorganic fillers in visible-light-cured dental composite resins. Inorganic fillers in seven visible-light (VL)-cured dental composite resins were examined for their size, composition, phase and content, employing the following analytical instruments. SEM observations indicated that five samples could be classified into the hybrid type while the remaining two belonged to micro-filled and sub-micron types. EDX analyses revealed that five samples contained BaO while others lacked BaO. XRD analyses showed that three were in vitreous phase, two were in the crystalline phase and two were mixtures of both. DTG thermal analyses indicated that the hybrid type composites had the higher inorganic filler content (wt%) than the composites of two other types. In conclusion, wide varieties exist in the inorganic fillers in VL-cured dental composite resins currently utilized.


Skin photosensitizing agents and the role of reactive oxygen species in photoaging. In this paper, the role of reactive oxygen species in photoaging is presented. Many photosensitizing agents are known to generate reactive oxygen species (singlet oxygen (1O2), superoxide anion (O2.-) and .OH radicals). Although photoaging (dermatoheliosis) of human skin is caused by UVB and UVA radiation, the hypothesis tested here in the pathogenesis of photoaging of human skin is the free radical theory involving the generation of reactive oxygen species by UVA (320-400 nm) radiation and their damaging oxidative effects on cutaneous collagen and other model proteins. The UVA-generated reactive oxygen species cause cross-linking of proteins (e.g. collagen), oxidation of sulfydryl groups causing disulfide cross-links, oxidative inactivation of certain enzymes causing functional impairment of cells (fibroblasts, keratinocytes, melanocytes, Langerhans cells) and liberation of proteases, collagenase and elastase. The skin-damaging effects of UVA appear to result from type II, oxygen-mediated photodynamic reactions in which UVA or near-UV radiation in the presence of certain photosensitizing chromophores (e.g., riboflavin, porphyrins, nicotinamide adenine dinucleotide phosphate (NADPH), etc.) leads to the formation of reactive oxygen species (1O2, O2.-, .OH). Four specific observations are presented to illustrate the concept: (1) the production of 1O2 and O2.- by UVB, UVA and UVA plus photosensitizing agents (such as riboflavin, porphyrin and 3-carbethoxypsoralens) as a function of UV exposure dose, the sensitizer concentration and the pH of the irradiated solution; (2) the formation of protein cross-links in collagen, catalase and superoxide dismutase by 1O2 and O2.- (.OH) and the resulting denaturation of proteins and enzyme activities as a function of UVA exposure dose; (3) the protective role of selective quenchers of 1O2 and O2.- (e.g. alpha-tocopherol acetate, beta-carotene, sodium azide, ascorbic acid, etc.) against the photoinactivation of enzymes and the prevention of the protein cross-linking reaction; (4) the possible usefulness of certain antioxidants or quenchers that interact with the UVA-induced generation of reactive oxygen species in the amelioration of the process of photoaging.


Relationship between photosensitizing activities and chemical structure of hypocrellin A and B. Hypocrellins A (HA) and B (HB) are two main pigments isolated from the parasitic fungi Hypocrella bambusae (B. et Br) Sacc. and Shiraia bambusicola P. Heen found in China. These pigments have a long history as traditional medicinal agents. Although HA and HB have the same perylene quinonoid structure, there are different side rings. The different photosensitizing activities of HA and HB due to their different side rings were studied by electron paramagnetic resonance (EPR), spin trapping and spin counteraction techniques. It is demonstrated that the ability to generate active oxygen (1O2, O2.- and .OH) is stronger during HA photosensitization than during HB photosensitization. Under anaerobic conditions, the ability to generate HA.- during HA photosensitization is stronger than the ability to generate HB.- during HB photosensitization. There is a relationship between photosensitizing ability and chemical structure.


Photosensitization by anticancer agents. 11. Mechanisms of photosensitization of human leukemic cells by diaminoanthraquinones: singlet oxygen and radical reactions. The synthesis of several aminoanthraquinone derivatives (AAQs), designed to suppress the dark toxicity and to promote more efficient cancer cell photosensitization for potential use in photodynamic therapy (PDT), is described. The following AAQs were synthesized: 1-NH2-4,5-(MeO)2-AQ (1), 1,5-(NH2)2-4,8-(MeO)2-AQ (2), 1,8-(NH2)2-4,5-(MeO)2-AQ (3), and 1,5-(NHPhMe)2-4,8-(MeO)2-AQ (8). The agents exhibit strong absorption in the region 480-620 nm. Possible mechanisms of photosensitization were studied by measuring 1O2 phosphorescence at 1270 nm, detecting superoxide radicals employing an electron paramagnetic resonance (EPR)-spin trapping technique, and measuring oxygen consumption during the photo-oxidation of a representative biological electron donor, NADH. Strong phosphorescence from 1O2 was observed upon illumination of 2 and 3 in C6H6 (quantum yield of 0.25 and 0.5 respectively), and in EtOH (quantum yield of 0.23 and 0.34). The 1-amino-AQ (1) was the weakest 1O2 sensitizer, with quantum yield of 0.13 in benzene. No phosphorescence was observed in EtOH. A superoxide radical was detected as a spin adduct of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) in irradiated benzene solutions of 1, 2 or 3 and DMPO. AAQs 2 and 3 sensitized photo-oxidation of NADH in H2O/EtOH mixture with the intermediacy of singlet oxygen as judged by the effect of sodium azide on the photostimulated oxygen consumption. Evolution of O2 upon addition of catalase to the illuminated solution confirmed the ultimate formation of hydrogen peroxide. These findings suggested that the (di)amino-dimethoxyanthraquinones might exert photosensitization via both Type I and Type II mechanisms. The AAQs were tested for their ability to photosensitize K562 human chronic myeloid leukemic cells in culture. Viability was measured using the 3,4,5-diethylthiazol-2,5-diphenyl tetrazolium blue assay, and DNA and possible membrane damage were assessed. The results from illuminating cells with light > 475 nm show that for the 1,5-compounds, the presence of methoxy substituents at 4,8 positions reduces the dark toxicity from ID50 of 23 to 250 microM and for the 1,8-compounds correspondingly from ID50 of 53 to > 300 microM. In the 1,5-series this decrease of the dark toxicity is accompanied by an increase in light-induced dose modification from 8.85 to 14.4. Differences exist in the mechanisms of cytotoxicity between the prototype phenolic AAQs and their methoxy counterparts. It appears that the cytotoxic action of the latter causes cell damage by the formation of a high proportion of alkali labile sites in addition to frank strand breaks.(ABSTRACT TRUNCATED AT 400 WORDS)


Calcium therapy for calcitriol-resistant rickets. Ten patients with calcitriol-resistant rickets caused by a defect in the ligand-binding domain of the vitamin D receptor are described. Eight patients, 1.7 to 13.8 years of age, received high doses of elemental calcium (range, 0.4 to 1.4 gm/m2) through indwelling intracaval catheters for periods of 1.8 to 3.8 years. Two other patients, aged 1.1 and 2.2 years, were given oral calcium therapy as the sole mode of treatment. In five of the intravenously treated patients, oral calcium therapy was initiated after radiologic evidence of healing of the rickets. To maintain normal serum calcium concentration, the patients required daily doses of elemental calcium of 3.5 to 9 gm/m2 body surface area. Clinical improvement was observed within a week of the start of intravenous therapy, with disappearance of bone pain; several of the younger patients started to walk for the first time. Growth velocity increased within 2 to 3 months, from a pretreatment rate of -0.8 to -6.3 standard deviation score (SDS), to a posttreatment rate of +0.1 to +5.1 (SDS). Serum calcium, parathyroid hormone, phosphorus, and alkaline phosphatase values returned to normal within a year. Radiologic signs of healing occurred more rapidly in the intravenous treatment groups and in younger patients. Episodes of septicemia occurred frequently in those receiving parenteral therapy and required replacement of the catheter. We recommend that in the treatment of calcitriol-resistant rickets, oral calcium therapy be started at the youngest possible age, in doses to the limit of intestinal tolerance. When rickets is present, calcium should be infused through a large vessel in doses high enough to produce normocalcemia, normophosphatemia, and suppression of parathyroid hormone. Only after radiologic healing has been observed can oral calcium therapy be introduced.


Extrarenal Wilms' tumor: results of the National Wilms' Tumor Study. Extrarenal Wilms' tumor is extremely rare and occurs predominantly in children. Eight cases of extrarenal Wilms' tumor were reported to the National Wilms' Tumor Study from 1980 to 1986. Patients were followed in the study and not randomized to a particular treatment protocol. Seven patients had a favorable histology. One tumor located in the sacrococcygeal region showed immature teratoma with nephroblastic tissue. The embryogenesis of extrarenal Wilms' tumor is controversial; however, tumor containing teratomatous elements most likely represents a different embryologic origin and, therefore, should be classified separately. All eight patients were treated with operative excision and chemotherapy. Seven of the eight patients were disease-free with a mean follow-up of 34.3 months. It can be inferred from this small group of patients that the prognosis is comparable to intrarenal Wilms' tumor in the National Wilms' Tumor Study.


Studies on responsiveness of hepatoma cells to catecholamines. VI. Characteristics of adrenoceptors and adenylate cyclase response in rat ascites hepatoma cells and human hepatoma cells. Alpha 1, alpha 2- and beta-Adrenoceptor densities and catecholamine responsiveness in established hepatoma cells, rat ascites hepatoma AH13, AH66, AH66F, AH109A, AH130 and AH7974 cells and human hepatocellular carcinoma HLF and HepG2 cells, were compared with those in normal rat hepatocytes and Chang liver cells. Alpha 1-Adrenoceptor densities measured by [3H]prazosin bindings were not detected in all hepatoma cell lines. Alpha 2-Adrenoceptor densities measured by [3H]clonidine bindings were also barely detected in hepatoma cell lines except for AH130 cells and HepG2 cells. Regarding beta-adrenoceptor, AH109A, AH130 and AH7974 cells had much more [125I]iodocyanopindolol binding sites than normal rat hepatocytes, although we could not detect the binding in HepG2 cells. Adenylate cyclase of normal rat hepatocyte and Chang liver cells were stimulated by beta 2-adrenergic agonist salbutamol, while the cyclase in hepatoma cells had no beta 2-adrenergic response but a beta 1-type response. These findings indicate that the characteristics of adrenergic response in hepatoma cell lines is very different from that in normal hepatocytes, suggesting a participation in the hepatocarcinogenesis and/or the autonomous proliferation of hepatoma cells.


Mechanism of hepatic microsomal oxidation of 11-hydroxy-delta 8-tetrahydrocannabinol to 11-oxo-delta 8-tetrahydrocannabinol. Evidence for hydration of the aldehyde formed. Hepatic microsomal oxidation of 11-hydroxy-delta 8-tetrahydrocannabinol (11-OH-delta 8-THC) to 11-oxo-delta 8-THC was investigated. Hepatic microsomes from mice, rats, guinea pigs and rabbits catalyzed the oxidation of 11-OH-delta 8-THC to 11-oxo-delta 8-THC together with the formation of dihydroxy-delta 8-THCs oxidized at the 7-position or at the pentyl side chain of 11-OH-delta 8-THC. 11-Oxo-delta 8-THC formed under oxygen-18 gas was analyzed by gas chromatography-mass spectrometry (GC-MS) indicating that molecular oxygen was not significantly incorporated into the aldehyde formed. 11-Oxo-delta 8-THC formed from 11-18OH-delta 8-THC (18O/16O = 0.81 - 1.05) was also found to lose oxygen-18 from the molecule. These results suggest that 11-oxo-delta 8-THC is hydrated in the incubation mixture and the aldehyde oxygen is exchangeable with the oxygen atom of water. When 11-oxo-delta 8-THC was incubated with hepatic microsomes and phosphate buffer containing H2 18O (44 atom%), GC-MS analysis indicated the incorporation of oxygen-18 into the aldehyde recovered from the incubation mixture. The results suggest that the hepatic microsomes may facilitate the hydration of 11-oxo-delta 8-THC and exchange an oxygen atom of the aldehyde group with that of water in the incubation mixture.


Evaluation of biodegradable microspheres as vaccine adjuvant for hepatitis B surface antigen. Biodegradable microspheres were evaluated as vaccine adjuvants based on their ability to provide prolonged release of incorporated agents. Hepatitis B surface antigen (HBSA) prepared by recombinant DNA technology was chosen as a model antigen and encapsulated into polyglycolic acid (PGA) by solvent extraction and solvent evaporation techniques. Five microsphere formulations were prepared to evaluate effect of microsphere size and the presence of immunostimulants such as muramyl dipeptide (MDP) or aluminum hydroxide. The microspheres were characterized for size distribution, surface morphology and antigenicity. Guinea pigs were chosen as the animal model for evaluation of antigenicity of the formulations. The animals were divided into seven groups of four animals each and the microsphere formulations were injected intraperitoneally, using alum adsorbed HBSA as positive control and placebo microspheres as negative control. Blood samples were withdrawn from the animals by toe clipping at two, four, six and sixteen weeks and plasma was analyzed for antibodies against hepatitis B by an enzyme linked immunoassay. At sixteen weeks, the animals were reinjected and evaluated for antibody response at two, four and six weeks post second injection. Antibody response to the microspheres was higher than control. Smaller size microspheres elicited earlier antibody response while the larger size microspheres provided delayed and longer duration of antibody production. Microspheres with MDP potentiated the antibody response. The results demonstrate the applicability of biodegradable microspheres for immunization against hepatitis B.


In vitro autoradiographical localization of melatonin binding sites in the caprine brain. The recent development of a specific 2-[125I]-iodo-melatonin ligand has led to the identification of 125I-melatonin binding sites in the brains of numerous mammalian species. The present study reports the localization of 125I-melatonin binding sites in the brain of the dairy goat. Six previously untreated female goats, aged 5-7 years, were culled under natural light between 0900 and 1100. Brains and pituitaries were immediately dissected out and frozen on dry ice. Both transverse and sagittal sections of frozen brain were cut 20 microns thick and thaw-mounted onto gelatin-coated slides. Three consecutive sections were cut at intervals throughout the brain, mounted onto three slides, labeled A, B, and C, and thusly treated: (A) incubated for 2 hr at room temperature in a 50 pM solution of 125I-melatonin; (B) incubated for 2 hr at room temperature in a 50 pM solution of 125I-melatonin plus 1 microM cold melatonin; (C) fixed in Clarke's fluid and stained with toluidine blue. After incubation, A (specific) and B (nonspecific) slides were washed three times in ice-cold Tris-HCl buffer (pH 7.7), air-dried, exposed to an X-ray film for 2 weeks at -20 degrees C, and then fixed and stained. Specific 125I-melatonin binding sites were found in the pars tuberalis (PT), the area of the suprachiasmatic nucleus (SCN), preoptic area (POA), fornix/mediolateral septal areas, hippocampus, and the cerebral cortex. 125I-melatonin did not bind in the hindbrain, midbrain, neurohypophysis, pars intermedia or pars distalis of the adenohypophysis, or the pineal.


[The study of Chinese herbal medicinal prescription with enzyme inhibitory activity. VII. The study of inchinko-to with adenosine 3',5'-cyclic monophosphate phosphodiesterase]. A Chinese herbal medicinal prescription, Inchinko-to, was studied for the inhibitory activity on adenosine 3',5'-cyclic monophosphate (cAMP) phosphodiesterase (PDE). The inhibitory activity on cAMP PDE of the extract of each constituent from the crude drug and of several compounds isolated from the drug was studied. By changing the combination ratio of two kinds of the crude drugs from 1:1 to 1:5, the inhibitory activity on cAMP PDE was estimated and it was found to be highest at the ratio of 1:3 in Rhubarb and Gardenia fruit, and at 1:4 in Rhubarb and Capillaris buds. These were the same ratio which is now commonly used for Chinese herbal medicinal prescription in Japan. Similar results were obtained in the combination test of the components of the crude drug such as emodin, geniposide, capillarisin and dimethylesculetin. The effects of Inchinko-to and its prescription which lacks one of the constituents of the crude drugs on carbon tetrachloride inducing liver injury in mice were also studied. Among the four prescriptions the antihepatotoxic activities were observed in the prescriptions containing Capillaris buds. Correlation between the administrated content of dimethylesculetin and antihepatotoxic activity was not recognized.


Fetal cocaine exposure causes persistent noradrenergic hyperactivity in rat brain regions: effects on neurotransmitter turnover and receptors. Fetal cocaine exposure has been shown to cause neurobehavioral abnormalities related to ontogeny of catecholaminergic systems. In the current study, pregnant rats received cocaine (30 mg/kg s.c. daily) from gestational days 8 through 20 and markers of presynaptic and postsynaptic noradrenergic function were monitored in the offspring from birth to young adulthood. Animals in the cocaine group had normal body and brain region weights, and norepinephrine levels showed only minor differences from control values. However, fetal cocaine exposure produced marked noradrenergic hyperactivity, as assessed by norepinephrine turnover. The effect was selective for noradrenergic synapses, as dopamine levels and turnover were largely unaffected. The regional hierarchy of effects on norepinephrine turnover corresponded to the timetable of cell replication/differentiation, namely midbrain + brainstem > forebrain > cerebellum; the resemblance of this pattern to that for effects of glucocorticoids and hypoxia on noradrenergic cell differentiation suggests that cocaine alters development of noradrenergic activity by eliciting fetal hypoxia/ischemia and a consequent release of endogenous glucocorticoids. Effects of fetal cocaine exposure on development of adrenergic receptor subtypes (alpha-1, alpha-2 and beta receptors) were separable from those on noradrenergic presynaptic activity, exhibiting a different regional selectivity. Because cocaine exposure caused an increase in receptor binding superimposed on the increase in presynaptic activity, both factors are likely to contribute to a net synaptic hyperactivity and resultant behavioral teratogenesis.


Intrathecal St-587: effects on nociceptive reflexes and blood pressure in the rat. The purpose of this study was to determine the effect of i.t. St 587 (lumbar injection) on tail-flick (TF) latency and paw pressure (PP) withdrawal threshold in conscious rats, and the effect of i.t. (midthoracic injection) and i.v. St 587 on blood pressure in urethane-anesthetized rats. Unlike i.t. methoxamine (alpha 1 agonist), which produced antinociception, i.t. St 587 (0.5-30 micrograms) decreased TF latency and PP threshold below base line. Hyperalgesia was also produced by i.t. Wy 27127 (alpha 2-selective antagonist). At i.t. doses of St 587 > 3 micrograms, there was an apparent but incomplete return of TF latency and PP threshold toward base line. Pretreatment with i.t. prazosin (2.5 micrograms) enhanced the hyperalgesic effect of 30 micrograms, but not 1 microgram of St 587. Intrathecal St 587 and Wy 27127 each antagonized the antinociceptive effect of i.t. guanfacine (alpha 2 agonist) in the TF and PP tests. Intravenous St 587 produced a dose-dependent pressor effect that was antagonized by pretreatment with i.v. prazosin (0.14 mg/kg; 52-fold increase in the ED50), but weakly antagonized by Wy 27127 (0.5 mg/kg; 1.5-fold increase in the ED50). ST-587 also produced a dose-dependent pressor response after i.t. injection which was antagonized by i.t. prazosin (10 micrograms) or i.v. hexamethonium (10 mg/kg).(ABSTRACT TRUNCATED AT 250 WORDS)


Characterization of [3H]morphine binding to interleukin-1-activated thymocytes. We have previously reported that interleukin-1-induced proliferation of thymocytes is accompanied by the appearance of [3H]morphine binding sites on these cells. In the present study, we have characterized these binding sites. They differ from classical opioid receptors in the brain in several ways, including: 1) lack of stereoselectivity; 2) relatively low affinity (Kd = 50 nM) and high capacity (Bmax = 3 pmol/mg of protein); 3) binding is strongly inhibited by Ca++, Mg++, Mn++ and Cl- ions and 4) binding is inhibited by proteinase K or E and by phospholipase A2 but not trypsin treatment of thymocyte membranes. The binding sites, which were found largely on the CD4+ subset of T-cells, also showed a preference for opioid alkaloids over peptides. These [3H]morphine binding sites may mediate a negative feedback effect on interleukin-1-induced proliferation of thymocytes in vivo.


Effects of tacrine on insulin secretion and 86Rb+ and 45Ca++ efflux from rat pancreatic islets. Tacrine (1,2,3,4-tetrahydro-9-aminoacridine), a drug that has attained interest because of its ability to alleviate symptoms in Alzheimer's type of dementia, was found to stimulate insulin secretion from isolated rat pancreatic islets. The insulinotropic effect of the drug was observed at 8.3 mM but not at 3.3 mM glucose and was dependent on extracellular Ca++. From perifused 86Rb(+)-prelabeled islets, tacrine inhibited the fractional efflux of 86Rb+ at 3.3 mM glucose, but stimulated 86Rb+ efflux at 8.3 mM glucose. These effects persisted in the absence of extracellular Ca++. Tacrine also stimulated 45Ca++ efflux from perifused 45Ca(++)-prelabeled islets at 8.3 mM but had no effect on 45Ca++ efflux at 3.3 mM glucose or in the absence of extracellular Ca++. It is concluded that tacrine potentiates glucose-stimulated insulin secretion by a mechanism that is dependent on extracellular Ca++ and involves an increased Ca++ influx. The increased Ca++ influx is either secondary to a decreased K+ permeability induced by an inhibition of ATP-dependent K+ channels and/or due to a direct effect of tacrine on glucose-activated Ca++ channels.


Acute effects of cocaine on plasma adrenocorticotropic hormone, luteinizing hormone and prolactin levels in cocaine-dependent men. Acute cocaine administration alters secretion of anterior pituitary hormones in experimental animals, and cocaine abuse may compromise neuroendocrine function in humans. The goal of this study was to examine cocaine's acute effects on neuroendocrine hormones in cocaine-dependent men. Plasma adrenocorticotropic hormone (ACTH), luteinizing hormone and prolactin levels were measured in 18 men before and after i.v. administration of cocaine (30 mg) or placebo. Each subject served as his own control during the i.v. placebo and cocaine administration conditions. Plasma cocaine levels peaked at 260 ng/ml within 5 min after the i.v. injection. Plasma ACTH levels increased significantly above base-line levels at 5, 15, 30 (P < .01) and 45 min (P < .05) after i.v. cocaine. Plasma luteinizing hormone levels increased significantly above base-line levels at 5 (P < .05) and at 15 min (P < .01) after i.v. cocaine. No changes in plasma ACTH or luteinizing hormone levels were found after i.v. placebo injection. Plasma prolactin levels decreased significantly at 30, 45, 60, 90 and 120 min (P < .01) after both i.v. cocaine and placebo administration. Cocaine-induced increases in plasma ACTH levels may be due to its effects on dopaminergic systems which modulate corticotropin-releasing factor release in brain.


Effect of chronic administration of verapamil on Ca++ channel density in rat tissue. The purpose of this study was to determine if chronic administration of verapamil could alter the density of Ca++ channels in the heart as determined by [3H]PN 200-110 binding. Initially, we compared the effects of verapamil given by s.c. injection or via implantable, slow-release verapamil pellets. We found the majority of animals treated with the pellets died within 24 hr. Those that survived exhibited significantly depressed maximal binding and Kd values for PN 200-110 binding to cardiac membranes, but binding to brain membranes was unaffected. Quantitation of the serum levels of verapamil and its metabolites by high-performance liquid chromatography demonstrated that the verapamil pellets did not release the drug evenly over a 3-week period. Most of the drug was released in toxic quantities during the 1st day after implantation. Verapamil administered by injection (2.5-30 mg/kg/day) for up to 16 weeks raised plasma verapamil levels to 25 to 250 ng/ml, but had no effect on Ca++ channel characteristics in cardiac or brain tissue. The maximal binding and Kd values for skeletal muscle PN 200-110 binding were increased only at the highest dosage for 8 weeks duration. Our results demonstrate that implantable pellets are not a reliable administration method for verapamil and cardiac Ca++ channels are highly resistant to change during chronic verapamil administration.


The pharmacological activity of nitroxyl: a potent vasodilator with activity similar to nitric oxide and/or endothelium-derived relaxing factor. Chemical oxidation of N-hydroxy-L-arginine (NOHA) and other N-hydroxyguanidines has been previously shown to generate either nitric oxide (NO) or nitroxyl (HNO), depending on the oxidative conditions. Because N-hydroxy-L-arginine has been demonstrated to be a biosynthetic intermediate in the oxidative conversion of arginine to endothelium-derived relaxing factor, the possible formation of HNO through a biological process was considered. This study, therefore, explores the biological activity of HNO as a possible effector molecule, and the results indicate that HNO is capable of eliciting vasorelaxation in both rabbit aorta and bovine intrapulmonary artery by a guanylate cyclase-dependent pathway. The pharmacological properties of HNO were very similar to those of endothelium-derived relaxing factor, and the possible relationship between HNO and endothelium-derived relaxing factor is discussed.


[3H]2-phenylaminoadenosine ([3H]CV 1808) labels a novel adenosine receptor in rat brain. Earlier studies have demonstrated that the vasoactive compound CV 1808 displays 10-fold selectivity for the adenosine A2 receptor, and as such, was the first reported A2-selective agonist. After the radiolabeling of CV 1808, its binding characteristics were evaluated in rat striatal, cortical and hippocampal membranes. Using 5 nM [3H]CV 1808, unlabeled CV 1808 produced shallow inhibition curves in all three brain areas, with 61 to 75% of the binding displaying IC50 values of 16 to 24 nM, whereas the remaining 28 to 37% of binding had lower affinity (IC50 595-1130 nM). The A2-selective agonist CGS 21680 and the nonselective adenosine agonist 5'-N-ethylcarboxamidoadenosine displayed very low affinity (IC50 > 10 microM). The A1-selective compound N6-cyclopentyladenosine inhibited only 28 to 44% of specific binding, with IC50 of 272-1750 nM. In contrast, the nonselective adenosine antagonist CGS 15943A inhibited specific binding by 48 to 64% (at 1 microM) with IC50 ranging from 106 to 295 nM. Additionally, several novel adenosine analogs fully inhibited specific binding, producing multicomponent inhibition curves. Electrophysiological studies in porcine coronary artery cells demonstrated that CV 1808, but not CGS 21680, 5'-N-ethylcarboxamidoadenosine and N6-cyclopentyladenosine, activated potassium channels. Further, the CV 1808-induced activation was blocked by CGS 15943A. These results indicate that [3H]CV 1808 binding consists of two components in rat brain: a low-affinity site with A1-like characteristics, and a novel high-affinity site, designated as the A4 receptor, where potassium channel activation appears to be a functional correlate.


General anesthetics potentiate gamma-aminobutyric acid actions on gamma-aminobutyric acidA receptors expressed by Xenopus oocytes: lack of involvement of intracellular calcium. Potentiation of the gamma-aminobutyric acid (GABAA) receptor-gated Cl- channel response has been suggested to be a primary action of some anesthetic agents. We asked whether the GABAA receptor is a target site common for general anesthetics that are chemically and structurally diverse. This hypothesis was tested in Xenopus oocytes expressing mouse cortical mRNA, and GABA-activated Cl- currents were measured using two-electrode voltage clamping. General anesthetics, including inhalational (halothane, diethylether, enflurane and isoflurane), i.v. (3 alpha-hydroxy-5 alpha-dihydroprogesterone, ketamine and propofol) and alcohol (pentanol) anesthetics, enhanced GABA-induced currents by 56 to 1089% at concentrations that were clinically relevant. The results suggest that potentiation of the GABAA receptor/channel response may be a common action for anesthetic agents. Moreover, anesthetic effects were dependent on GABA concentrations; the enhancement was marked with low GABA concentrations and was exponentially decreased as the GABA concentration increased. Also, anesthetic effects were dependent on anesthetic concentrations. The apparent EC50 of halothane was found to be similar to the anesthetic ED50. We also investigated the role of intracellular Ca++ in mediating anesthetic enhancement of the GABA current. We found that intracellular injection of the Ca++ chelator, EGTA, did not change the enhancement by anesthetics. In addition, these anesthetics alone did not produce significant currents, suggesting that the Ca(++)-dependent Cl- current was not activated by these anesthetics per se. Thus, we found that diverse anesthetics potentiate GABA-induced Cl- currents, but this action is not mediated by a release of intracellular Ca++.