Protective efficacy of conjugate vaccines against experimental challenge with porcine Actinobacillus pleuropneumoniae. In an attempt to protect pigs against swine pleuropneumonia induced by Actinobacillus pleuropneumoniae (SPAP) by neutralizing the effects of three virulence factors of A. pleuropneumoniae--the capsular polysaccharide (CP), the lipopolysaccharide (LPS), and the hemolysin protein (HP)--two subunit conjugate vaccines were prepared by covalently coupling the CP to the HP and the LPS to the HP. The CP, LPS, and HP were isolated from A. pleuropneumoniae, strain 4074, serotype 1, and the protective efficacy of the conjugate vaccines in swine experimentally infected with A. pleuropneumoniae was evaluated. Following a booster vaccination, a significant (P < 0.05) IgG antibody response to the CP, LPS, and HP was detected in the vaccinated pigs. The pigs vaccinated with the CP-HP and LPS-HP conjugates exhibited significantly less mortality (P < 0.05) and significantly greater weight gain (P < 0.001) than unvaccinated pigs. Vaccinated pigs exhibited significantly fewer and less extensive gross pulmonary lesions (P < 0.001) when compared with unvaccinated pigs. Thus, on the basis of mortality, weight gains, and pulmonary lesion formation, the two conjugate vaccines used in conjunction with one another provide noticeable protective efficacy against SPAP.


Ivermectin: its effect on the immune system of rabbits and rats infested with ectoparasites. The influence of subcutaneously administered ivermectin on the specific immune response was studied in rabbits infested with mites (Psoroptes cuniculi) and in rats infested with lice (Polyplax spinulosa). A pronounced specific antibody activity and a change in immunoblotting pattern was observed in rabbits after the ivermectin treatment. However, in rats the antibody activity decreased and the profile of specific antibodies, tested by immunoblotting, remained the same as before the treatment. The specific immune response in rabbits artificially immunized with whole-body Psoroptes cuniculi extract was not affected by ivermectin. It was concluded that ivermectin has no direct effect on the immune response of rabbits and rats and that the enhanced immune response in the mite-infested rabbits was caused by the massive release of antigens associated with the synchronous death of the mites.


Duck lymphocytes. VI. Requirement for phagocytic and adherent cells in lymphocyte transformation. Preparations of duck (Anas platyrhynchos) spleen and blood lymphocytes depleted of cells capable of phagocytosing carbonyl iron gave lower transformation responses to the mitogens phytohaemagglutinin (PHA), concanavalin A (Con A), Bandeiraea simplicifolia seed lectin (BSS), wheat germ agglutinin (WGA), lentil lectin (LL) and phorbol ester (PMA) than intact cell preparations. When cell populations were fractionated on the basis of their adherence to plastic, it was found that the adherent cells were responsive to PHA, Con A, BSS, WGA and PMA, while the non-adherent cells responded to LL. These observations confirm the expected requirement for phagocytic accessory cells in the induction of in vitro mitogen-driven duck lymphocyte responses. The responses of plastic-adherent populations of cells to most mitogens are believed to reflect the generally close physical relationship between the adherent accessory cells and the lymphocytes, although it remains possible that duck monocytes respond to some of the mitogens employed. The data also suggest that LL stimulates a population of cells different to those responding to other mitogens.


Changes of silver-stained nucleolar organizer regions in mouse endometrial carcinogenesis induced by N-methyl-N-nitrosourea and 17 beta-oestradiol. A high incidence of endometrial adenocarcinoma and pre-neoplastic lesions was induced in ICR mice treated with N-methyl-N-nitrosourea and 17 beta-oestradiol within 23 weeks. The endometrial lesions were histopathologically similar to those of human subjects. To assess the cell proliferative activity of these lesions, a one-step silver colloid staining for nucleolar organizer regions was applied and the numbers of silver-stained nucleolar organizer regions (AgNORs) were counted. The mean numbers +/- SD of AgNORs in each lesion were as follows: simple hyperplasia, 2.07 +/- 0.36; complex hyperplasia without cytological atypia, 2.79 +/- 0.39; complex hyperplasia with cytological atypia, 3.43 +/- 0.38; and well-differentiated adenocarcinoma, 4.17 +/- 0.40. Significant differences were observed in each lesion (P < 0.001). These findings suggest that the mean numbers of Ag-NORs are increased in the progression of neoplastic changes in the mouse endometrium, as in human endometrial lesions. This rapid induction model of endometrial carcinoma in mice is useful in the understanding of the histogenesis of endometrial carcinoma in human subjects.


Immunohistological analysis of tumour infiltrating lymphocytes in seminoma using monoclonal antibodies. Immunological characterization of tumour infiltrating lymphocytes (TIL) by immunohistological techniques was carried out in 20 cases of stage I seminoma. Routine pathological examination of these surgical specimens showed typical seminoma in 20 cases. Eighteen cases showed obvious TIL and immunohistological staining on frozen specimens was performed in 12. TIL in seminomas were predominantly T-cells but B-cells were also identified. T-cells were distributed diffusely with predominance of the CD8+ phenotype judged semiquantitatively. In contrast to the distribution of T-cells, B-cells tended to accumulate and occasionally formed lymphoid follicles. In such follicles the phenotypic pattern of B-cell antigens was comparable with secondary lymphoid follicles in lymphoid organs. There is an immunologically complex response to seminoma by the host with a predominant infiltration of cytotoxic/suppressor T-cells and functional maturation of B-cells.


Interneuronal interaction between members of quadrature phase and anti-phase pairs in the cat's visual cortex. Interactions between adjacent simple cells recorded simultaneously from the same microelectrode placement were studied by correlational analysis. The receptive fields of pairs of such cells exhibit either 90 degrees (quadrature phase) or 180 degrees (anti-phase) phase relationships. We now show that the majority of quadrature phase pair members do not receive common input from the immediately precedent stage along the visual pathway, nor do these cells interact with each other. The anti-phase pairs show relatively strong mutual inhibition. These results suggest that each of the physically adjacent phase-related simple cells receives excitatory input from a distinct group of pre-cortical cells, and that mutual inhibitions between members of anti-phase pairs are used to construct the inhibitory subzones of these cells. We propose a model which incorporates these new results and provides a parsimonious explanation for the construction of both quadrature phase and anti-phase pairs.


Paramyxovirus-like nuclear inclusions identical to those of Paget's disease of bone detected in giant cells of primary oxalosis. Nuclear inclusions, identical to those characteristic of Paget's disease of bone, were observed in giant cells in four of eight cases of primary oxalosis. The giant cells containing nuclear inclusions were directly involved in phagocytosis of large oxalate crystals in the context of typical foreign body granulomas in the bone marrow. Cytochemically, all of them exhibited strong tartrate-resistant acid phosphatase activity, and a proportion of them also tartrate-resistant acid ATPase. The inclusions consisted of typical arrays of filamentous material as described in Paget's disease, admixed with variable proportions of electron-dense material closely reminiscent of nucleolar pars fibrillaris and fibrillary centres. These data indicate: (a) the occurrence of Paget-like inclusions in a bone disease unrelated to Paget's disease, not causally related to viral infection, and resulting from an inborn metabolic derangement; and (b) the occurrence of Paget-like inclusions in foreign body giant cells as opposed to osteoclasts. We suggest that the occurrence of paramyxovirus-like nuclear inclusions in either osteoclasts or giant cells may represent an epiphenomenon of cell fusion and giant cell formation whenever appropriate stimuli act on latently infected precursor cells. Furthermore, our data suggest that nucleoli may represent the specific site of virus-like inclusion formation.


The effects of aging on the pattern electroretinogram and visual evoked potential in humans. We have recorded patterns electroretinograms (PERGs) and visual evoked potentials (VEPs) from 14 elderly subjects (mean age 72 yr) and 12 young subjects (mean age 21 yr) in response to stimulation by high contrast sinusoidal grating patterns of variable spatial frequency (at 9 Hz) and temporal frequency (at 1.7 c/deg). The major effect of aging on the PERG was an aspecific reduction in amplitude (of about 40%) at most spatial and temporal frequencies, together with a small but systematic phase lag. Control measurements suggest that senile miosis may be responsible for the phase lag, but not for the reduction in amplitude. The effects of aging on the VEP were more dramatic and depended on the spatial and temporal properties of the stimulus. VEP amplitudes (at 1.7 c/deg) were significantly lower for the aged at low temporal frequencies (below about 6 Hz), but were similar at high temporal frequencies. At 9 Hz, there was no effect of spatial frequency on VEP amplitude. At high temporal frequencies (above 10 Hz), the latencies of VEPs (estimated from the rate at which phase varied with temporal frequency) were similar for old and young (94 and 99 msec respectively). Below 10 Hz, however, the latencies of the old observers was much greater (153 compared with 108 msec). The second-harmonic phase of VEPs of the old but not the young decreased considerably with spatial frequency, by about 1.9 pi radians (52 msec) over the range from 0.5 to 11 c/deg. The selective reduction in amplitude at low temporal frequencies, the longer latencies at low temporal frequencies and the phase lag at high spatial frequencies are consistent with the hypothesis that mechanisms sensitive to high spatial and low temporal frequencies are selectively degraded by aging.


Effect of light scatter on the pattern reversal visual evoked response: comparison with psychophysical results. The effect of light scatter on the pattern reversal visual evoked response (PVER) was studied in 6 normal subjects. The results were compared with contrast visual acuity, contrast sensitivity function, and glare disability. Light scatter was induced by translucent acrylic sheets. Visual acuity measured with the low-contrast charts decreased significantly (P < 0.0001) even with a small degree of light scatter. Contrast sensitivity decreased with a small degree of light scatter especially for high spatial frequencies. PVER amplitudes decreased especially at the smaller checks with its peak shifted to larger checks. PVER was equally sensitive to light scatter compared to psychophysical tests.


Retinal and cortical activity in human subjects during color flicker fusion. Pattern electroretinograms (PERG) and cortical visually evoked potentials (VEP) were simultaneously recorded from 7 visually normal and 1 protanopic subjects. Stimuli were color checkerboards (0.5 degrees check size), phase-reversing at 17 Hz (i.e. 34 reversals/sec). Using a stepwise sweep procedure, the luminance of the red (lambda peak = 550 nm) and green (lambda peak = 630 nm) checks varied in 11 steps in opposite directions from 0 to 30 cd/m2, embracing the subjective equiluminance point. For normal subjects at subjective equiluminance, the VEP amplitude dropped sharply down to 13 +/- 2% of the value at pure luminance contrast. The PERG, however, was only reduced to 56 +/- 10% at this point, an attenuation 4 times less than that of the VEP. In contrast to normal subjects, in the protanopic subject the PERG was sharply reduced at equiluminance, parallel to the VEP. This would be expected when L-cones are missing. Assuming that the PERG reflects the activity of the retinal ganglion cells, our findings suggest that human retinal ganglion cells respond well under the condition of equiluminant flicker fusion, which is in agreement with recent single-cell studies in the monkey. Consequently, the temporal low-pass filter, which mediates color-flicker fusion, would seem to lie central to the retinal ganglion cells.


Three-dimensional properties of human pursuit eye movements. For any given location and velocity of a point target, there are infinitely many different eye velocities that the pursuit system could use to track the target perfectly. Three-dimensional recordings of eye position and velocity in 8 normal human subjects showed that the system chooses the unique tracking velocity that keeps eye position vectors (a particular mathematical representation of three-dimensional eye orientation) confined to a single plane, i.e. pursuit obeys Listing's law. One advantage of this strategy over other possible ones, such as choosing the smallest eye velocity compatible with perfect tracking, is that it permits continuous pursuit without accumulation of ocular torsion. For nonpoint targets, there is at most one eye velocity compatible with perfect retinal image stabilisation, and the optimal velocity may not fit Listing's law; we observed small but consistent deviations from the law during pursuit of rotating line targets.


Sawtooth contrast sensitivity: effects of mean illuminance and low temporal frequencies. Temporal contrast sensitivity was measured for mirror-image sawtooth (rapid-on and rapid-off) and sine waveforms for a 1.8 deg foveal target. In one experiment, contrast sensitivity was measured for 2-26 Hz stimuli at target mean illuminance levels of 5-1260 td. At 5 td, contrast sensitivity functions for sawtooth and sine waveforms, expressed in terms of the Fourier fundamental amplitude, are equivalent. At higher light levels, sawtooth sensitivity increasingly exceeds sine sensitivity and rapid-off (decremental) sawtooths show progressively greater sensitivity than rapid-on (incremental) sawtooths. This pattern of results was obtained for two color-normal observers and for a deuteranopic observer. In a second experiment, sawtooth and sine sensitivity was tested at 500 td with an extended low-frequency range, to 0.5 Hz. Rapid-off and rapid-on sensitivities declined only slightly at low temporal frequencies in contrast with sine sensitivity. To interpret our data, we evaluate two single-pathway models (last-stage asymmetric detector and compressive response-intensity non-linearity) and a dual-pathway model in which incremental and decremental waveforms are detected by separate ON and OFF visual mechanisms.


Age-dependent intensity-difference thresholds in pigeons. Recent studies have reported age-related deficits in visual acuity and changes in retinal morphology in pigeons. The experiment reported here was designed to determine the effects of age on intensity difference thresholds in pigeons. Six subjects, age 2-17 yr, were trained to discriminate between two stimuli that differed in luminance. When this training was complete, the subjects were presented with a series of stimulus comparisons ranging from 0.08 to 0.43 log unit. Threshold was calculated by determining the luminance difference that corresponded to 75% correct. These data were pooled with 56 intensity-difference thresholds that had been collected from pigeons of various ages over a 20 yr period using the same procedure. A regression analysis that was performed on the pooled data set gave the result b = 0.0038, d.f. = 61 P < 0.05, r2 = 0.066 which indicates that age accounted for approx. 7% of the variance in intensity-difference threshold. This finding, although statistically significant, indicates that as pigeons age their ability to perform this type of non-spatial discrimination task is not greatly impaired. This finding suggests that deficits associated with a spatial visual task in pigeons, such as visual acuity, are task specific and are not due to a global performance deficit.


Isoluminant stimuli may not expose the full contribution of color to visual functioning: spatial contrast sensitivity measurements indicate interaction between color and luminance processing. Visual performance is greatly impaired when tested with heterochromatic isoluminant stimuli. It is thus concluded that the chromatic system contribution to many visual tasks is limited. We suggest that unless color and luminance are shown to be processed independently, such experiments do not demonstrate shortcomings of the chromatic system but rather the inadequacy of using isoluminant stimuli for isolating that system. We hypothesize that color vision has evolved not only to encode color per se but also to enhance luminance-based visual processing, so that for color information to be fully effective, luminance as well as chromatic variations should be present in the stimulus. The hypothesis was tested by studying the contribution of color to spatial vision. The human contrast sensitivity function (CSF) was studied using luminance, isoluminance (color) and combined luminance/color sinusoidal gratings. It is found that luminance contrast sensitivity is enhanced when luminance contrast is accompanied by color contrast and vice versa. The nature of the interaction is best described by an additive single analyzer model. Color opponent cells which respond to both chromatic and achromatic stimuli may be identified as the analyzer.


Moving two-dimensional patterns can capture the perceived directions of lower or higher spatial frequency gratings. Coherent plaid motion is produced by superimposing two one-dimensional gratings of the same spatial frequency moving +/- 60 degrees from the intersection-of-constraints (IOC) resultant direction. These moving plaids were found to change the perceived direction of a third one-dimensional grating, either 6-fold lower or higher in spatial frequency, from traveling in one of the plaid's component direction to the IOC resultant direction. We describe this phenomenon as coherence capture. Coherence capture was found to be effective between plaids with 0.5, 1.0, and 1.5 c/deg components and gratings of 3.0, 6.0 and 9.0 c/deg respectively. It was also found to be effective between plaids with 3.0 c/deg components and gratings of 0.5 c/deg. However, coherence capture between higher spatial frequency plaids and lower spatial frequency gratings became less effective when the component spatial frequencies of the plaid increased.


The optics of the spherical fish lens.

The optics of the spherical fish lens. The optical design of the fish eye is particularly simple because immersion renders the cornea optically ineffective and the lens is nearly spherical in shape. Measurements have shown that an approximately parabolic gradient of refractive index exists within the lens. If full internal and external spherical symmetry of the lens applies, the geometrical-optical behaviour of the lens is then a function only of the refractive index of the surrounding medium, that of the lens core and cortex, and of the form of the index gradient. The theoretical optical performance of models of the spherical fish lens is calculated by means of the ray-tracing program Drishti as a basis for understanding the optical design of real fish and aquatic eyes. Models based on the gradients proposed by earlier workers are shown to be unable to predict reported spherical aberration and image quality. A model of the fish lens with a polynomial gradient is proposed that yields spherical aberration, image quality and chromatic aberration similar to that reported for the fish.


Robustness of perception of heading from optic flow. Heading discrimination in optic flow stimuli was investigated in 5 humans. Flow patterns consisted of a computer generated motion sequence which showed a mixture of randomly moving and coherently-moving points. The motion of the coherently-moving fiducial points was completely determined by the changing position of the observer's simulated vantage point. Ego-rotation as well as ego-translation was simulated. Noise and fiducial points were confined to the ground plane in most experiments. In one experiment the points formed a cloud with no visible horizon. The results indicate that heading perception is robust against degradation of the flow-field by the presence of noise or by the reduction of the lifetime of the fiducial points. The results suggest that points, which move independently from the reference frame as formed by the fiducial points, are to a large extent removed from the analysis of optic flow by the visual process which derives the heading. The motion of recognizable points at infinity (like the horizon) appears to be essential for robust heading perception in the presence of ego-rotations.


The effect of adaptation on the differential sensitivity of the S-cone color system. This paper presents a psychophysical dissection of the S-cone color system. Experiments were guided by a skeletal model that assumed a first stage consisting of S-, M- and L-cones, and a second stage of the opponent combination of the S and L+M signals. The response of the S-cone system was isolated by measuring difference thresholds between lights that were equiluminant tritanopic confusion pairs and thus differed only in S-cone excitation. Two types of mechanisms that control sensitivity in the S-cone system were identified: (i) static mechanisms that have a restricted range and thus limit discrimination to a small range of inputs; and (ii) adaptive mechanisms that change the state of the system in response to changes in steady illumination, so that the system is sensitive to small changes from the adapting light. These mechanisms were localized by lights that stimulated the S-cone system while keeping the signal constant at either the S, the L+M, or the post-opponent stage. The response function of the static mechanism was estimated by measuring difference thresholds at judgment points other than the steady adapting light. This procedure was repeated at a number of adaptation lights to examine the properties of adaptive mechanisms. The data were consistent with an elaborated model that included identical multiplicative gain control mechanisms in the S and L+M pre-opponent branches, and a post-opponent static sigmoidal nonlinearity with different amounts of compression for positive and negative opponent inputs.


The spatial localization deficit in amblyopia. There have now been numerous reports of a spatial localization deficit in amblyopia but none so far have tackled (1) the relationship between the contrast sensitivity and spatial localization deficits and (2) whether the spatial localization deficit is best described in units of visual angle or in terms of the underlying filter size. These issues are germane because they lie at the very heart of our understanding of the underlying deficit in amblyopia. To answer these questions we use spatially bandpass stimuli so that we can readily compare detection and localization for the same stimuli at each of a number of spatial scales. For some amblyopes (all strabismics and a minority of anisometropes) the contrast sensitivity defect neither underlies nor covaries with the spatial localization deficit. In the majority of anisometropic amblyopes, the contrast sensitivity loss is a complete description. The spatial localization deficit in amblyopia is of two independent kinds; positional inaccuracy and positional distortion. The positional inaccuracy deficit which can occur in varying degrees in both strabismic and anisometropic amblyopia, affects all spatial scales equally and therefore is best thought of in terms of a constant fraction of the underlying filter size in the space-frequency plane. The positional distortion deficit which can also occur to varying degrees in both strabismic and anisometropic forms can not be easily understood within this metric at least for strabismics.


Static roll and pitch in the monkey: shift and rotation of Listing's plane. In three rhesus monkeys three-dimensional eye positions were measured with the dual search coil technique. Recordings of spontaneous eye movements were made in the light and in the dark, with the monkeys in different static roll or pitch positions. Eye positions were expressed as rotation vectors. In all static positions eye rotation vectors were confined to a plane, i.e. Listing's plane was conserved. Tilt about the roll axis shifted the plane along this axis, i.e. a constant torsional component was added to all eye positions. Tilt about the pitch axis changed the pitch angle of Listing's plane.


The two-dimensional shape of spatial interaction zones in the parafovea. The spatial analysis of a target may be strongly degraded by the simultaneous presentation of nearby pattern elements. The present study investigated the shape and extent of the region of interaction as a function of retinal location. The stimuli consisted of 3 collinear [symbol: see text] s which were randomly oriented up ([symbol: see text]) or down ([symbol: see text]). The task was to discriminate the orientation of the middle [symbol: see text]. The retinal locations studied were at 0, 2.5, 5 and 10 degrees, on the lower vertical meridian and on the nasal halves of both the horizontal and the 45 degrees diagonal visual field meridians. The extent of the interaction region was defined as the separation between the midpoint of two adjacent [symbol: see text] s that resulted in 75% correct discrimination. The shape of the interaction region was determined by using several orientations (horizontal, vertical, left diagonal and right diagonal) for the virtual line joining the 3. [symbol: see text] s. Our results show that the size of the interaction regions varies linearly with eccentricity as does the size of a just resolved individual [symbol: see text]. However, the size of the interaction region varies much more rapidly than does the resolution threshold for an individual [symbol: see text]. The spatial interaction zones appear to be elongated radially, so that they have an elliptical shape. The size of the major axis is about 2-3 times the size of the minor axis. The major axis is along the meridian through the central visual field (i.e. it is oriented radially) while the minor axis is oriented tangentially (i.e. isoeccentrically).


An operational approach to colour constancy. Colour constancy is traditionally defined as the invariance of perceived surface colours under changes in the spectral composition of the illuminant. Existing quantitative studies show that, by this definition, human subjects show poor colour constancy. A different and complementary aspect of colour constancy is considered which is concerned with the ability of a subject to attribute correctly changes in the colour appearance of a scene either to changes in reflecting properties of the surfaces that make up the scene, or to changes in the spectral composition of the illuminant. Data are presented showing that, if the changes in the appearance of a scene were sufficiently great, subjects were capable of making the required discriminations highly reliably, and without scrutiny.


Mobility performance with a pixelized vision system. A visual prosthesis, based on electrical stimulation of the visual cortex, has been suggested as a means for partially restoring functional vision in the blind. The prosthesis would create a pixelized visual sense consisting of punctate spots of light (phosphenes). The present study investigated the feasibility of achieving visually-guided mobility with such a visual sense. Psychophysical experiments were conducted on normally sighted human subjects, who were required to walk through a maze which included a series of obstacles, while their visual input was restricted to information from a pixelized vision simulator. Walking speed and number of body contacts with obstacles and walls were measured as a function of pixel number, pixel spacing, object minification, and field of view. The results indicate that a 25 x 25 array of pixels distributed within the foveal visual area could provide useful visually guided mobility in environments not requiring a high degree of pattern recognition.


Modeling the dynamics of light adaptation: the merging of two traditions. Light adaptation has been studied using both aperiodic and periodic stimuli. Two well-documented phenomena are described: the background-onset effect (from an aperiodic-stimulus tradition) and high-temporal-frequency linearity (from the periodic-stimulus tradition). These phenomena have been explained within two different theoretical frameworks. Here we briefly review those frameworks. We then show that the models developed to predict the phenomenon from one tradition cannot predict the phenomenon from the other tradition, but that the models from the two traditions can be merged into a class of models that predicts both phenomena.


An analysis of the VEP to luminance modulation and of its nonlinearity. Identification of the VEP luminance modulation system was carried out using a relatively long pseudorandom binary m-sequence stimulus. The complete first order cross-correlation function provides a "fingerprint" of the nonlinearity in the time domain. Volterra kernel slices up to third order are recognized in the complete first order cross-correlation function. They all lie close to the major diagonal. Higher order kernel slices are not measurable. A cascade block model (sandwich model) analysis shows the nonlinearity to be an asymmetric rectification. Luminance increase causes a stronger response than does luminance decrease. The pre-filter gain function is low-pass. The post-filter gain function is band-pass tuned near 10 Hz. Coherency spectra are used to examine the channel structure of the system. Two channels operating near 8 and 15 Hz are easily identified. Another broad channel (or possibly multiple channels) is present above 30 Hz. In many subjects, the pseudorandom stimuli allow a complete system identification to be carried out in less than 82 sec.


An intensity-dependent biphasic neuron in mudpuppy retina. Intracellular recordings in dark-adapted mudpuppy retinas have revealed a type of infrequently encountered cell with unusual response properties. These cells may be a subclass of horizontal cell since they are encountered at the same depth as horizontal cells and have large receptive fields and response amplitudes. However, they differ from typical horizontal cells in that they are depolarized by low intensity illumination and hyperpolarized by higher intensity illumination at all wavelengths. Both types of responses appear to be driven mainly by 572 nm cones. Both the depolarizing and hyperpolarizing responses were unaffected by APB, indicating that they are not mediated by on-center bipolar cells.


Cortical neurons: isolation of contrast gain control. The selectivity of cortical neurons remains invariant with contrast, even though the contrast-response function saturates. Both the invariance and the saturation might be due to a contrast-gain control mechanism. To test this hypothesis, a drifting grafting was used to measure the contrast-response function, while a counterphase grating was simultaneously presented at the null position of the receptive field (where it evokes no response at any contrast). When the contrast of the counterphase grating increased, the contrast-response function shifted primarily to the right. This result is consistent with the hypothesis that there is a fast-acting gain-control mechanism which effectively scales the input contrast by the average local contrast.


On the relation between ERG waves and retinal function: inverted rod photoresponses from the frog retina. In rod mass receptor photoresponses recorded across the isolated frog retina, a paradoxical cornea-positive wave may precede the response of normal polarity. We present a model which shows that the light-induced decrease in rod current can give rise to inverted or biphasic ERG signals if the distal part (tip) of the rod outer segment responds more slowly and/or less sensitively than the proximal part (base). The condition is that current entering at the tip is represented with greater weight in the ERG. The model reproduces recorded ERG waveforms well. It further predicts that if there is a light-insensitive conductance in the tip membrane, ERG photoresponses may be non-recordable although current photoresponses are only slightly reduced. The model reveals a type of complexity in the relation between mass potentials and underlying physiological processes which has not previously received attention.


Color fusion and flicker fusion frequencies using tritanopic pairs. We determined color fusion and flicker fusion frequencies for tritanopic color pairs, so that only short wavelength sensitive cones were modulated. The minimally distinct border (MDB) technique was used to determine tritanopic pairs for each observer. If S-cones do not contribute to the luminance channel, color fusion and flicker fusion frequencies should be equal, because the achromatic flicker perceived beyond color fusion frequency is supposed to be elicited just by the luminance channel. The results show a significant difference between color fusion and flicker fusion frequencies for all pairs and for all subjects, which suggests a contribution of S-cones to the luminance channel. However, the results also showed that the residual achromatic flicker can not be eliminated by adjusting relative luminance of two colors flickering in counter-phase. The relative luminance stayed the same as the MDB setting when residual flicker was minimized. This means that minimum flicker was obtained when L- and M-cones are temporally silenced, and suggests little or no contribution of S-cones to luminance channel. These conflicting results might be explained by phase shift between responses of S-cones and other longer-wavelength-sensitive cones.


The Bezold-Brücke effect in the color vision system of the honeybee. Evidence is presented that intensity dependent color shifts (Bezold-Brücke effect) occur in the color vision system of the honeybee. The evidence comes from a fit between the choices of monochromatic lights in training experiments (Menzel, R., 1981; Journal of Comparative Physiology A, 141, 389-393) and the choice percentages derived now from recently presented quantitative predictions from the color opponent coding (COC) model for the bee (Backhaus, W., 1991; Vision Research, 31, 1381-1397) for the Bezold-Brücke effect. The only open parameter in the simulations of the training experiments is an experiment type dependent factor describing the weighting of color differences (judgement values) in the choice behavior. The results show (1) that the Bezold-Brücke effect exists in the bee. The results (2) confirm the color opponent coding (COC) model which was developed to describe the physiological components of the color vision system in the bee, (3) the general psychophysical assumptions about the structure of the color space, (4) the color difference formula, and (5) the general psychophysical assumptions about the (triadic) structure of judgements as tested in color similarity experiments.


On the scaling of size judgements by orientational cues. Observers carried out multiple, concurrent size discriminations with a range of size standards. The task was to classify each stimulus as larger or smaller than the appropriate standard size for the set to which it belonged. The set to which each stimulus belonged was indicated by its orientation, or in different experiments, by its spatial location. Observers were able to maintain appropriate discrimination, both when there were four concurrent standards and when there were eight. Both angle and position functioned as effective cues. The size of the orientational cue appeared to make little difference to the efficiency of discrimination. However, when the relationship between standard size and orientation was random, rather than regular, performance got worse. The analogy between such discrimination and size constancy is pointed out, and the results are discussed in relation to Andrews, D. P.'s [(1964) Quarterly Journal of Experimental Psychology, 16, 104-115)] account of perceptual calibration.


The precision of size constancy.

The precision of size constancy. The precision of objective size judgments, made when target disparity changed at random from trial-to-trial, was compared to the precision of angular size judgments made under the same condition. Subjects judged incremental changes in the vertical distance separating a pair of horizontal lines. For the objective judgments (in cm), the angle subtended by the target separation decreased with increasing depth consistent with the natural geometry of physical objects. For the angular judgments (in arc min), the angular separation did not change with disparity. For separations subtending an angle < 10 arc min, objective thresholds were considerably higher than angular thresholds, indicating that size constancy does not function well at small scales. At larger scales (> 20 arc min), the Weber fractions for angular and objective thresholds were nearly equal (approximately 6%) for two of the three subjects. These same two subjects also learned to judge "objective size" when angular subtense systematically increased with increasing depth in an exact inversion of the natural relationship. Although their "anti-constancy" judgments were less precise (approximately 9%) than their constancy judgments, the fact that subjects could learn this task with little practice suggests that constancy itself may be a learned response. Angular thresholds for targets presented only in the fixation plane were significantly lower than the angular thresholds measured with random changes in disparity, showing that observers with normal stereopsis do not have direct access to information about the angle subtended at the retina.


Fourier analysis of the stimuli for pattern-induced flicker colors. Pattern-induced flicker colors (PIFCs) were observed and color matched in rotating discs from which higher-harmonic Fourier components in the square-wave temporal luminance functions of a conventional black-and-white Benham disc had been removed. Since both reddish-brown and blue PIFCs were visible with purely sinusoidal stimuli they cannot result from differences in temporal stimulus shape or pattern and do not provide evidence for a temporal coding theory of color. Green PIFCs differed in that they did require the presence of additional harmonics. In a second experiment the luminance means upon which the sinusoidal PIFC stimuli were imposed were varied. The results show that color is determined by the phase of the time-varying contrast between the two parts of the stimulus pattern. This points to a site proximal to the outer plexiform layer for the phase-sensitive interaction causing PIFCs.


Failure of rivalry at low contrast: evidence of a suprathreshold binocular summation process. Presentation of different images to the two eyes normally results in a time-varying alternation between the two images (binocular rivalry). However, we find that when orthogonal gratings are viewed dichoptically at low contrast, a stable summation between the two images is perceived in the form of a dichoptic plaid. The range of perception of the dichoptic plaid depends on spatial frequency, contrast and luminance of the gratings. This phenomenon differs from the "false fusion", a fleeting summation of different images perceived only under very brief presentation of the stimuli. The observations suggest that there exists a neural process that performs a summation of dissimilar images, and that is distinct from the competitive process of suppression and binocular rivalry.


Spatial scaling of vernier acuity tasks. Vernier acuity thresholds for two abutting lines and for a two-dot stimulus were measured as a function of stimulus magnification at eccentricities of 0, 5, 10 and 15 deg using a spatial scaling technique in which all stimuli are simply magnified versions of each other. The advantage of such a technique is that no prior knowledge of a suitable magnification factor with which to increase the size of peripheral stimuli is required. Thresholds for the line stimulus could be successfully scaled by the application of a magnification factor with an E2 value of 1.23-1.78 deg. Further, provided that the effects of dot separation and eccentricity were dissociated, spatial scaling with an E2 value of 1.06-1.96 deg was also successful in removing eccentricity dependence for two-dot vernier thresholds.


Brightness, discriminability and the "crispening effect". Subjects adjusted the luminances, L, of 16 or 25 circles, all visible at the same time on a computer monitor, to make equal-interval brightness series. The background was black, white or grey. The luminance steps between adjacent circles behaved like the luminance discrimination thresholds of Whittle, P. [(1986) Vision Research, 26, 1677-1691)]. They showed a sharp minimum at the background luminance, Lb: the "Crispening Effect". They followed Weber's Law with respect to L when L was small, but with respect to delta L (= magnitude of L-Lb) near Lb. The Crispening Effect was abolished by a thin outline or a hue difference between circles and background.


Spectral transmittance of the rat lens.

Spectral transmittance of the rat lens. The spectral transmittance of the isolated rat lens for radiation of wavelengths from 300 to 700 nm was measured using a spectrophotometer. Transmittance decreased from 93-95% at 700 nm, to 70-80% at 400 nm, 50-60% at 360 nm, 4-18% at 320 nm, and to < 2% at 310-300 nm. These results indicate that the rat lens is remarkably transparent for UVA radiation, which has consequences for rat vision, and for interpretation of earlier studies on retinal light damage.


The role of binocular vision in prehension: a kinematic analysis. This study examined the contribution of binocular vision to the control of human prehension. Subjects reached out and grasped oblong blocks under conditions of either monocular or binocular vision. Kinematic analyses revealed that prehensile movements made under monocular viewing differed substantially from those performed under binocular conditions. In particular, grasping movements made under monocular viewing conditions showed longer movement times, lower peak velocities, proportionately longer deceleration phases, and smaller grip apertures than movements made under binocular viewing. In short, subjects appeared to be underestimating the distance of objects (and as a consequence, their size) under monocular viewing. It is argued that the differences in performance between the two viewing conditions were largely a reflection of differences in estimates of the target's size and distance obtained prior to movement onset. This study provides the first clear kinematic evidence that binocular vision (stereopsis and possibly vergence) makes a significant contribution to the accurate programming of prehensile movements in humans.


Inhibitory interaction in a split/fusion apparent motion: lack of spatial-frequency selectivity. Spatial-frequency selectivity of apparent motion (AM) between isolated Gabor patches was examined under two- and three-patch conditions. In the two-patch condition, the likelihood of seeing AM between two Gabor patches was measured with varying frequency difference between the patches. In the three-patch (split/fusion) condition, the likelihood of AM between target patches of the same frequency was measured as a function of the frequency of the inhibiting patch. AM perception in the two-patch condition deteriorated with increasing frequency difference, showing symmetrical spatial-frequency selectivity. On the other hand, the inhibition of AM in the three-patch condition was frequency asymmetric; when the frequency of the inhibiting patch was higher than that of the target patches, the magnitude of inhibition decreased with increasing the frequency of the inhibiting patch. When the frequency of the inhibiting patch was lower, the magnitude of inhibition remained almost constant regardless of the frequency difference between the inhibiting and target patches.


Human speed perception is contrast dependent. When two parallel gratings moving at the same speed are presented simultaneously, the lower-contrast grating appears slower. This misperception is evident across a wide range of contrasts (2.5-50%) and does not appear to saturate (e.g. a 50% contrast grating appears slower than a 70% contrast grating moving at the same speed). On average, a 70% contrast grating must be slowed by 35% to match a 10% contrast grating moving at 2 degrees/sec (N = 6). Furthermore, the effect is largely independent of the absolute contrast level and is a quasi-linear function of log contrast ratio. A preliminary parametric study shows that, although spatial frequency has little effect, relative orientation is important. Finally, the misperception of relative speed appears lessened when the stimuli to be matched are presented sequentially.


Redness from short-wavelength-sensitive cones does not induce greenness. According to opponent-colors theory, a reddish surround induces greenness in a central test field. Color-appearance measurements verify this with a long-wavelength reddish surround (660 nm) but not with a short-wavelength reddish surround (440 nm). Surprisingly, a short-wavelength reddish surround shifts the appearance of a test toward redness. Four possible explanations are: (1) stray light from the short-wavelength reddish surround falls in the test area; (2) receptoral sensitivity changes overwhelm induced greenness from the surround; (3) a neural process of assimilation, rather than contrast, to the surrounding light; and (4) short-wavelength-sensitive (S) cones do not contribute to induced redness/greenness. Chromatic cancellation experiments confirm the fourth explanation. There was no change in induced redness/greenness when quantal absorption by only S cones in the surround was varied by 30-fold (using tritanopic metamers), even though varying stimulation of S cones strongly affected the color appearance of the surround. The redness induced by a short-wavelength surround is accounted for by opponent chromatic induction mediated by only middle- and long-wavelength-sensitive cones.


The development of vernier acuity in human infants. Vernier acuity, i.e. the detection of a small misalignment between lines, is about one order of magnitude finer than the resolution of periodic gratings in adult humans. This hyperacuity is generally attributed to cortical mechanisms, and the time-course of its development seems to differ from the development of grating resolution that probably is limited by retinal factors. We investigated 271 human infants and children between 2 months and 8 yr of age with essentially identical stimuli and experimental procedures. Vernier thresholds for Vernier targets were compared to grating resolution. The preferential looking experiments led to the following results: (i) Vernier acuity starts below grating resolution. (ii) Like grating resolution, Vernier acuity develops gradually, but more rapidly and longer; at the age of 5 yr performance becomes comparable to that of adults. (iii) Flanking borders without offset, added to the Vernier targets at various distances, did not affect thresholds consistently across distances and age groups.


A multi-channel approach to brightness coding. A model of brightness coding is presented which is shown to predict the appearance of a number of classical brightness phenomena. The model is known as MIDAAS which stands for Multiple Independent Descriptions Averaged Across Scale. In common with many other approaches to brightness perception MIDAAS imputes to local feature detectors a central role in the computation of brightness. It also explicitly recognises the crucial importance to brightness perception of feature detectors operating at different spatial scales. The unique and definitive feature of the model however is the supposition that each scale of spatial filtering operates as if to generate its own description of the pattern of brightness relationships in the image. The final percept is then provided by the composite of those individual brightness descriptions. It is shown that MIDAAS provides a good account of a variety of Mach band phenomena, the conditions under which the Missing Fundamental illusion is observed, the effect of occluding bars on the apparent contrast of step edges, the Chevreul illusion, simultaneous brightness contrast and the non-linear appearance of high contrast sinusoidal gratings. The advantages of MIDAAS over other approaches to brightness perception is discussed, as well as its current limitations.


The eyespot of Euglena gracilis: a microspectrophotometric study. The eyespots in cells of streptomycin-bleached strains and of dark-grown cultures of Euglena gracilis, were examined by means of fluorescence microscopy and microspectrophotometry. When viewed with light in the region of 380-500 nm, the stigma appeared as a dark spot. Adjacent to this was a second spot, not seen with white light, but which was seen to fluoresce when excited with radiation at 370 +/- 20 nm. This fluorescence proved to be polarized in contrast to other fluorescing bodies in the cell. The absorption curves, obtained by microspectrophotometry of individual eyespots, were found to consist of two spectral maxima, an A-band in the blue and a B-band in the green. Unlike the A-band, the B-band provided evidence of originating from an anisotropic structure. Relating these data to literature findings, we conclude that the B-band is the absorbance of a pigment in the quasi-crystalline paraflagellar body and the A-band perhaps a pigment in the orange-red stigma. The spectrum of the B-band does not appear to be that of a flavoprotein or of a free carotenoid but its resemblance to the spectrum of rhodopsin is significant in relation to published data for the Chlamydomonas eyespot that suggests the presence of a rhodopsin-like pigment as the photosensitive system responsible for phototaxis in this alga.


The eyespot of Chlamydomonas reinhardtii: a comparative microspectrophotometric study. The eyespot of Chlamydomonas reinhardtii is believed to utilize a rhodopsin-like pigment in its responses to light. This paper examines its eyespot by means of microspectrophotometry with the finding of an absorption spectrum with two bands, an A-band in the blue, and a B-band in the green. This spectrum is identical to that previously recorded from the eyespot of Euglena gracilis. As with Euglena the B-band was found to have dichroic character and its spectrum was similar to the absorption curve of rhodopsin. This A-B-spectrum was always recorded from a single granule in each cell. It is concluded that both E. gracilis and C. reinhardtii may utilize a rhodopsin-like pigment as the photopigment associated with the eyespot response to light. In both these algae a few particles in each cell were found whose spectra consisted of two other bands, C and D, blue- and red-shifted, respectively, relative to the eyespot A-B-bands. There is some reason to believe that the C-D-granules may also be involved in certain light-controlled activities of the cells.


Retinal perivascular astroglia: an immunoperoxidase study. Different morphological types of retinal perivascular astrocytes have been studied in wholemount preparations of rabbit retina. Astrocytes were immunohistochemically demonstrated using glial fibrillary acidic protein monoclonal antibodies (GFAP clone GA-5). Three types of perivascular astrocytes were found. Type I has an ovoid perikaryon which gives rise to numerous hair-like processes, and it shows strong GFAP reactivity; these cells are associated with medium-size vessels and capillaries. Type II is star-shaped and its spherical perikaryon has a basal cone with four to ten small, protruding, radial processes; these astrocytes show high GFAP reactivity and are located on larger and medium-size vessels. Type III astrocytes show the classic, star-shaped morphology in which processes emerge directly from the perikaryon which lacks a basal cone. However, different from Types I and II, Types III astrocytes show low GFAP reactivity and are positioned between capillaries. These cells are the only ones that can contact other astrocytes of the same type to form a network.


Development of temporal properties of pattern electroretinogram and visual evoked potentials in infants. The postnatal development of the temporal properties of the responses to pattern contrast reversal has been studied by recording simultaneously the pattern electroretinogram (PERG) and visual evoked potentials (PVEP) in infants 3-22 weeks old. The stimulus grating (0.5 c/deg) was either reversed in contrast sinusoidally at frequencies 4-10.5 Hz to study the temporal frequency function of steady-state responses, or square-wave reversed at 1 Hz to evaluate the peak latency of transient responses. Developmental changes of the shape and bandwidth of the temporal frequency function of both PERG and PVEP occur post-natally and are particularly pronounced between 13 and 20 weeks from birth, possibly indicating deferred maturation of classes of retinal and central neurons with higher temporal resolution. The peak latency of the PERG decreases during the age period tested to approach adult values towards the end of the fifth month. The rate of decrease of the peak latency of the PERG differs from that of the PVEP, indicating that post-retinal factors contribute largely to the maturation of the latter, especially in the earliest life period.


Color perception within a chromatic context: changes in red/green equilibria caused by noncontiguous light. We measured changes in the color appearance of one light caused by another light presented in a well-separated region. Observers viewed a 1 degrees test field superimposed on a 3 degrees, 540 or 660 nm adapting field (32 or 320 td). The change in appearance due to noncontiguous light was determined by surrounding the 3 degrees adapting field with a continguous 3 degrees i.d., 5 degrees o.d. ring of either 32 or 320 td. The ring was 540, 660 nm or achromatic (tungsten-halogen "white"). The test was an admixture of 549 and 660 nm light, and varied from 6 to 1000 td. The observer adjusted the ratio of 549 to 660 nm test light so the test appeared neither reddish nor greenish. A 540 or 660 nm ring had a chromatic inducing effect on the small test that mimicked a simple surround contiguous with the test. Results with an achromatic ring were more complex: an isolated achromatic ring (no adapting field present) had virtually no effect on the color appearance of the test, but the same achromatic ring surrounding a chromatic adapting field shifted the test toward the color appearance of the adapting light (e.g. introducing a "white" ring surrounding a "green" adapting field shifted the test toward greenness). A thin pencil-width band of "white" light superimposed on a larger 5 degrees adapting field had an effect similar to a "white" 3-5 degrees ring. These results demonstrate (1) strong effects of the remote noncontiguous lights and (2) that the change in color appearance they cause is not a simple function of only the light in the noncontinguous region. The change depends on other lights in view. The visual processes revealed in these experiments are considered in terms of inferred illumination and surface reflectances of objects in natural scenes.


Positive motion after-effect induced by bandpass-filtered random-dot kinematograms. Using spatially filtered random-dot kinematograms (RDK) with a 1 octave bandwidth, the duration and direction of motion aftereffect (MAE) were measured while varying step displacement, and the results were compared to those for motion direction discrimination. We found that MAE and motion discrimination show quite different dependencies on displacement. At displacements around 0.5 cycles of the lowest frequency, while motion discrimination was still almost perfect, normal MAE vanished and MAE in the same direction as that of the adapting stimuli, which we name "positive MAE", was observed. Similar results were obtained for both 1- and 2-dimensional filtered patterns. A theoretical examination based on the Fourier components of the stimuli showed that the displacement dependency of MAE is predictable in terms of adaptation of first-order detectors, but that of motion discrimination is not. The present results indicate that direction perception and MAE for bandpass RDKs are mediated at least partially by separate mechanisms, and that direction perception at larger displacements is mediated by the second-order mechanism which detects movement of contrast modulation in the image.


Calibration of three-dimensional eye position using search coil signals in the rhesus monkey. A procedure is described to calibrate three-dimensional eye position with a dual-search coil implant in rhesus monkeys using a two-field magnetic system. The method allows one to determine the sensitivity of the search coils taking into account the presence of d.c. offset voltages. The orientation of the implant on the eye relative to a space-fixed reference frame is computed using fixations of targets arranged vertically. The critical steps of the procedure are discussed and documented by experimental data.


Dissociation of orientation discrimination from form detection for motion-defined bars and luminance-defined bars: effects of dot lifetime and presentation duration. A stationary bar-shaped area that was perfectly camouflaged within a dot pattern was rendered visible by moving the dots inside and outside the bar at equal and opposite speeds. Orientation discrimination for this motion-defined (MD) bar was compared with orientation discrimination for a luminance-defined (LD) bar created by switching off all dots outside the bar. The best values of orientation discrimination threshold were similar for MD and LD bars at long presentation durations and long dot lifetimes. But, as presentation duration or dot lifetime was reduced below 1.0 sec, orientation discrimination threshold for MD bars increased at an accelerating rate, while discrimination for LD bars was comparatively unaffected. However, these effects of presentation duration and dot lifetime were largely due to changes in bar visibility. When bar visibility was normalised relative to the relevant bar detection threshold, the effect of presentation duration upon orientation discrimination was abolished for both MD and LD bars, and the effect of dot lifetime was abolished or even reversed. These observations dissociate detection and discrimination for MD and LD form. We suggest that orientation discrimination for MD and LD bars is determined by opponent-orientation mechanisms whose performance is not directly affected by presentation duration, nor degraded by reducing dot lifetime.


Depth discrimination of a line is improved by adding other nearby lines. Depth discrimination thresholds are shown to be lowered by up to a factor of 10 when a few reference lines are added to a stimulus containing a single isolated test line. Four reference lines are better than two, which are better than one, and the improvement in performance is greater when the test line lies between the two reference lines in depth. Stereoacuity for the relative depth of a target line, relative to other nearby reference lines, is shown to be insensitive to changes of disparity of the whole pattern of up to about +/- 5 arc min and is only weakly sensitive to larger displacements of up to +/- 10 arc min.


The conjugacy of human saccadic eye movements. Binocular measurements of instantaneous velocity vectors in normal human subjects during saccades showed: (1) considerable trial to trial variation in peak velocity, saccade duration, and saccade curvature despite saccade accuracy; (2) variations in one eye were mirrored by similar variations in the other eye, with a high positive correlation. The high correlation between the peak velocities suggest that saccades in the two eyes are driven by a common saccade generator. Assuming that a local feedback loop guides saccades, the high correlation between saccade durations and between saccade curvatures suggests that both eyes are guided by common feedback. If so, monocular adaptation must occur downstream from the saccade generator.


Disparity tuning in mechanisms of human stereopsis. The change in sensitivity across some stimulus dimension which follows adaptation to a particular stimulus can reveal a great deal about the tuning characteristics of underlying sensory/perceptual mechanisms. In this study, a psychophysical adaptation paradigm was employed to characterize the disparity tuning of perceptual mechanisms involved in stereopsis. The stimulus was a dynamic random-dot stereogram (DRDS) portraying a surface which varied in interocular correlation (IOC) and retinal disparity. Adaptation to a fully correlated DRDS surface produced an elevation in IOC threshold over a relatively narrow range of disparities, with maximum effect at the disparity of the adapting stimulus. The width of these disparity tuning functions varied from 5 arc min for adaptation at the horopter to 20 arc min for adaptation at 20 arc min disparity. Frequently, IOC sensitivity was enhanced for disparities on either side of the adapted disparity, suggesting that an opponent center-surround organization operates at an early level of disparity processing. A model of underlying channel structure consistent with these data is presented.


Lateral interactions within color mechanisms in simultaneous induced contrast. The perceived color of a region of visual space is a function not only of the spectral composition of the light incident from it, but also depends on the light incident from surrounding regions. The color contrast induced into a region is a result of lateral interactions between neural mechanisms. These interactions were studied by measuring the induced effect of circularly symmetric spatial sine-waves on a circular central test region. The phase of the surrounding sine-waves was changed uniformly in time, inducing a modulation in the appearance of the test. Observers adjusted the amplitude of real sinusoidal modulation in the test in order to null the induced modulation, and the nulling modulation was used as a measure of the induced effect. Spatial additivity was tested by using pairs of sine-waves of distinct spatial frequencies. The results showed that brightness induction can be characterized as a linear spatial process, i.e. the effects of parts of the surround at different distances from the test are summed, after the effect of each part is weighted by a negative exponential as a function of distance from the test. The magnitude of pure chromatic induction, however, is a result of nonlinear spatial interactions. Thus, these results have implications for the connections between visual mechanisms that process brightness and chromatic contrast.


Spectral sensitivities for illusory contour perception: a manifold linkage of chromatic and achromatic cues with the generation of contours. Using colored inducing patterns presented as increments upon a white uniform background, the increment thresholds needed for illusory contour perception were measured as a function of the wavelength of inducing pattern. The spectral sensitivity functions were obtained with varying adaptation level and stimulus configuration, high and low background illumination, and line-based and figure-based inducing patterns. The results showed a distinctive feature between the line-based and the figure-based illusory contours. The sensitivity functions for the line-based illusory contours showed the characteristics of non-opponent mechanisms and they were shape invariant with background intensity and spatial variables. On the other hand, the sensitivity functions for the figure-based illusory contours showed non-opponent nature for low background illumination but opponent nature for high background illumination. It is suggested that the generation of illusory contours involves concurrent processing of different cues of luminance and color, and that photopic adaptation level and stimulus configuration control the degree of the contributions of chromatic and achromatic mechanisms to contour formation.


The discrimination of blur in peripheral coloured borders. Our interest is in measuring the threshold for blur, for long borders at well-defined retinal eccentricities between large fields of colour. Our method is to precisely match a centrally fixated sharp-edged disk of one colour against a surround of another, using the minimum distinct border criterion. We then measure the amount of added Gaussian blur that makes the sharp step-edged border just noticeably different. The selected colours are small fixed chromatic deviations of 500 msec duration from an adaptive low photopic or mesopic white. The effects of retinal eccentricity are striking. Blur thresholds are large for yellow-blue borders centrally (at 1.25 degrees eccentricity) and extremely large for red-green borders peripherally (at 20 degrees). Blur thresholds are generally larger for isoluminous chromatic borders than for a low contrast achromatic border. Accurate Rovamo-Virsu M-scaling is limited to photopic achromatic borders.


Psychophysical and saccadic information about direction for briefly presented visual targets. For saccades, the difference between desired and actual eye movement (constant error), as well as the variability in amplitude on repeated trials (variable error), presumably represent a combination of errors in processing target position (sensory error) and errors in execution (motor error). To examine whether the saccadic system uses the same information about target position as visual perception, subjects made saccades to and psychophysical judgments about the location of targets presented for 17-200 msec. Mean saccadic amplitude markedly decreased and inter-trial variability increased when saccadic targets were presented briefly and followed by a spatial mask. Judged target position (from psychophysical vernier and bisection tasks) also shifted to lesser eccentricities and was more variable. Although qualitatively alike, changes with duration in saccadic constant errors were larger than could be accounted for by the psychophysical results, suggesting similar but separate processing of position information for the saccadic and perceptual systems. Differences in the sizes of collicular receptive fields that preferentially respond to targets at short and long durations can account qualitatively for the observed changes in saccadic amplitude as well as the common occurrence of saccadic undershoots.


Scotopic spectral sensitivity of phakic and aphakic observers extending into the near ultraviolet. Despite interest in ultraviolet (UV) damage and UV vision in lower vertebrates, there are few recent publications on human UV sensitivity. We obtained dark-adapted spectra from 4 aphakic and 5 normal eyes at 8.8 degrees off-fovea using the staircase method. Our measurements extended from 314.5 nm, near the limit imposed by corneal UV absorbance, to 650 nm. Phakic and aphakic sensitivities resembled the traditional rod spectrum at long wavelengths with a peak around 500 nm. However, aphakic subjects were much more sensitive than phakic observers below 420 nm. From phakic volunteers ranging in age from 22 to 43 we deduced lens absorbance which depressed sensitivity at 350 nm by approx. 4 log units (n = 7 phakic runs on 5 eyes, average age = 30) as expected. We show a maximum lens absorbance at 355-360 nm and a UV window in the lens absorbance at 315 nm consistent with data on optical density of human lenses.


Heterochromatic Fusion Nystagmus: its use in estimating chromatic equiluminance in humans and monkeys. The use of chromatic patterns that are equated for luminance has become increasingly popular in psychophysical and neurophysiological studies of visual processing. The currently available techniques for equating different colors for brightness rely upon human reports of perceptual events that are reduced at some luminance ratio. We report here the results of a study using a technique we have recently developed that produces a vivid and compelling motion percept only at isoluminance. That is, unlike previous methods, this technique relies upon a perceptual event (motion) that actually becomes more salient at isoluminance. We also observed that the optokinesis generated by the moving pattern mirrors the perceptual reports at all luminance ratios. If used in this manner, the technique can provide an estimate of chromatic isoluminance in a variety of species and can be used to corroborate a human subject's perceptual experience.


Spatiotemporal factors in infant position sensitivity: single bar stimuli. The ability of 3-month-old human infants to detect the presence of spatial misalignments in single-bar stimuli was investigated in a series of spatiotemporal stimulus manipulations. Both discrete and sinusoidal positional offsets, either stationary or temporally modulated, were presented using the forced-choice preferential looking technique. When discrete offsets were presented in alteration with the absence of offsets, thresholds were a factor of two worse than previous estimates of infant vernier acuity using grating stimuli. However, when offsets (discrete or sinusoidal) were presented in continuous motion, mean threshold was 22-24 arcmin, comparable to previous estimates using gratings with moving discrete offsets. For stimuli containing continuous motion, lowering velocity reduced infants' positional sensitivity. However, when either velocity or temporal frequency was held constant, the most important determinant of positional sensitivity was the sharpness of the offsets. The results from the temporally-modulated stimuli suggest that a simple local flicker mechanism cannot account for sensitivity when continuous motion is used in the stimulus; rather, a local motion mechanism may govern sensitivity in these conditions. We characterize this mechanism as one of "local motion" because it does have a position-sensitive component. The two stationary stimulus conditions in the present study indicate that infants can use a position-sensitive mechanism when no temporal modulation is present.


Lightness induction in the S-cone pathway. Lightness induction is classically regarded as a contrast phenomenon limited to pathways which process luminance information. To determine if lightness induction can also occur in the chromatic domain, this phenomenon was studied with stimuli visible only to the short wavelength sensitive (S)-cones which have post-receptoral connections limited to chromatic pathways. The lightness of an object visible only to S-cones was found to be dependent on the relative intensity of its background in a manner similar to achromatic, luminance stimuli. Less intense (dark) backgrounds made the object appear lighter, while more intense (light) backgrounds made the same object appear darker. These results indicate a commonality among lightness induction effect in the processing of chromatic and luminance information.


Absence of pupil response to blur-driven accommodation. The drive to the pupil constriction associated with near fixation has generally been attributed to accommodation with convergence and fusional convergence having secondary roles. However, our previous investigations have shown that significant changes in accommodation can take place without concomitant pupil response. To investigate further, the present study recorded pupil and accommodation responses to a blur-only accommodative stimulus using a target moved sinusoidally at a range of temporal frequencies. Care was taken to minimise target size change and apparent lateral or vertical target displacement. Results show that pupil response could be very much reduced or absent irrespective of stimulus temporal frequency and despite maintained accommodation response. The results suggest that blur-driven accommodation alone is not sufficient to drive pupil near response and that the presence of cues such as size change and lateral or vertical displacement of an approaching object may be necessary to elicit a response.


A square root law for adaptation to contrast? Several characteristic of aftereffects (especially the motion aftereffect) depend upon the square root of the time spent adapting. The same parameters are here examined for the contrast threshold elevation aftereffect. The time taken to recover is shown to be well predicted by root adaptation time (beyond a minimum duration), but the amount of threshold elevation, the rate of recovery and the integrated recovery phase cannot be so predicted.


The contributions of figure and ground textures to segmentation. Several models of texture segmentation use spatial gradients in the activity of early filters to locate texture boundaries. The models assume that these filters are identical to those involved in the detection and discrimination of near threshold patterns. The models differ in how activity gradients from different types of filters are combined. We examined this question by measuring the respective contributions of a figure and a ground texture to segmentation. Vertical and horizontal line segments were used to construct two perfectly discriminable textures and these textures were used to construct four types of displays. Each display contained an obliquely oriented figure, but the displays differed in the way this figure was defined. Displays consisted of either (1) a horizontally textured figure on a blank background, (2) a blank figure on a vertically textured background, (3) a horizontally textured figure on a vertically textured background or (4) a figure with a mixed texture (50% vertical lines, 50% horizontal lines) on a blank background. In a two-alternative forced-choice experiment, observers were asked to judge the figure's orientation (right or left oblique), and the contrast of the textures was varied across trials. The resulting psychometric functions for segmentation were very similar for the four types of displays, suggesting ways in which a simple model of segmentation should be modified.


[How should we implement the basic principles of treatment of type 2 diabetes mellitus from the aspect of the hormono-metabolic syndrome X (5H)?]. The authors summarize the principles of the therapeutic approach to the 5H syndrome [1. hyperinsulinism, 2. hyperglycaemia (NIDDM), 3. hyperlipoproteinaemia (obesity), 4. hypertension, 5. hirsutism], in particular its two components, i.e. NIDDM and arterial hypertension. The authors found that early treatment of hyperinsulinism, e.g. already in the stage of impaired glucose tolerance or NIDDM with oral antidiabetics, their disproportionate increase with regard to the blood sugar level and glycosylated haemoglobin without making "hygienic" provisions (radical weight reduction; increased physical activity to the maximum possible individual level; energy restricted diet in particular as regards carbohydrates and fat) does not prevent progression of the components of the 5H syndrome to the clinical stage. In treatment of arterial hypertension associated with 5H syndrome non-selective beta-blockers and thiazide diuretics are unsuitable because they worsen the HPLP and enhance insulin resistance. Suitable preparations are combinations of ACE-inhibitors, calcium antagonists, selective beta-blockers in particular with ISA and beta-blockers with a partial selective sympathomimetic activity (devalol and celiprolol). Hygienic provisions must be started in childhood, or when hyperinsulinism is detected.


[Abdominal ultrasonography].

[Abdominal ultrasonography]. The author characterizes ultrasonography as a modern diagnostic imaging method. The main attention is drawn to abdominal ultrasonography, especially to its indications and differential diagnostics. The author evaluates critically the present state and further foreseen development of this method. Finally he makes a statement on the question of safety.


[Emergency states in internal medicine--diagnostic contribution of emergency abdominal ultrasonography]. The authors analyzed the activities of the sonographic laboratory during four consecutive months. During this period 896 patients were examined by ultrasonography and 119 of them (13.3%) for urgently indicated ultrasonography. The authors present a detailed evaluation of results in these 119 examined patients, in particular from the aspect of yield and asset of the method, affection of different organs, agreement of clinical and sonographic diagnoses and comparison with some other examination methods. Urgent ultrasonography is recommended as a very useful method, in particular as regards diagnostic yield which makes it possible to establish the diagnosis quickly and thus to start appropriate treatment early and to reduce thus the period spent by the patient in hospital. The method is useful also in serious cases and in some conditions which threaten the patient's life, as it can help early indication of surgery.


[Monitoring immunosuppression after kidney transplantation. I. Study of cellular reactions to antigenic stimulus in a skin abrasion]. In 20 patients the authors performed in the course of 6-8 weeks following renal transplantation a total of 74 examinations of the cellular reaction to an antigenic stimulus. In 68 instances (91.9%) agreement with the clinical picture was recorded, while in 6 patients (8.1%) the interpretation of the cytological impression did not correspond to the clinical course. In four instances activation of lymphocytes was found, i.e. possible risk of rejection which however was not confirmed. In two instances however incipient rejection was not detected.


[Monitoring immunosuppression after kidney transplantation. II. Evaluation of simultaneous monitoring of CD4+ lymphocytes and the cytological reaction to standard antigenic stimulation]. Monitoring of patients after renal transplantations by the concurrent follow up of absolute values of CD4+ lymphocytes and the cytological reaction to an antigenic stimulation in a skin abrasion reflects the actual immune state of patients and is an asset in the comprehensive diagnosis of rejection activity against the transplant in the early period (6-8 weeks) after transplantation. It can contribute also to the signalling of developing rejection activity against the graft, before the onset of the fully developed clinical picture of rejection, when it is possible by early anti-rejection therapy to prevent the functional impairment of the renal graft.


[Disorders of lipid metabolism in type 2 diabetics]. The authors investigated the incidence of different disorders of the lipid metabolism and their age dependence in a group of 67 patients with type 2 diabetes hospitalized at the First Medical Clinic in Kosice. Some disorder of the lipid metabolism was recorded in 67% of the patients. The most frequently encountered disorder was hypertriglyceridaemia (21%). Hypercholesterolaemia was recorded in 16%, combined hyperlipidaemia in 18% and hypoalphalipoproteinaemia in 12% of the patients. Patients with diabetic nephropathy had significantly elevated mean triglyceride levels and reduced HDL-cholesterol levels, as compared with patients without nephropathy. In diabetic women a significantly higher incidence of combined hyperlipidaemias was recorded, as compared with men and the mean total cholesterol and triglyceride levels were also significantly higher in women with type 2 diabetes.


The effect of Hylak drops on symptomatology in persons with irritable bowel syndrome. The authors present an account on the therapeutic effect of Hylak drops of Merckle Co. in patients with irritable bowel syndrome. They assume that in the pathophysiological mechanism of the disease an important part is played by intestinal dysmicrobia. After two weeks' administration Hylak, 3 x 40 drops, they recorded in 20 patients with the exception of one female patient (where ex post lactose intolerance was revealed which is a contraindication of this treatment), partial or complete regression of subjective complaints in particular as regards intestinal discomfort and the number of imperative bowel movements. As to objective indicators, they proved changes in the pH of faeces and qualitative as well as quantitative changes of the microbial spectrum in faeces.


[Immunologic indicators in ascites].

[Immunologic indicators in ascites]. The authors investigated specific and non-specific immunological parameters in malignant, cirrhotic, cardial and nephrogenic ascites. At the same time bacteriological and cytological examinations of ascites were made. In the submitted paper the authors compare, using statistical methods, immunological parameters of ascites in different patient groups and pay attention to their relationship with positive bacteriological and cytological findings in ascites. The authors recorded the largest number of positive bacteriological cultivation in cirrhotic and malignant ascites which correlates with lower values of some non-specific immunological parameters in ascites.


[Secondary osteopenia. Iatrogenic causes of osteopenia]. The author investigated during the past 17 years 595 patients with iatrogenic damage of bone mineralization, incl. 302 patients where the disorder developed after drugs and 293 where osteopenia developed after surgery. In demineralizations after the use of drugs in the first place corticoids participate, to a smaller extent non-thiazide diuretics and antiepileptic drugs. The largest ratio of operations causing demineralization is formed by ovariectomies, in particular if performed before the menopause, followed by gastric surgery, operations of the gallbladder, small intestine and strumectomy. Finally the author emphasizes the necessity to know iatrogenic bone damage, its early diagnosis and prevention.


[Bronchial asthma. Pathogenesis and clinical aspects]. Asthma bronchiale (a.b.) is defined as paroxysmal or permanent, partly or completely reversible dyspnoea due to a bronchospasm resulting from pathological hyperreactivity of the bronchial system. In the pathogenesis participate allergic, immuno-infiltrative and genetic factors, irritating substances (environment) and infectious. The allergic constituent acts via sensitization and allergization of the mast cell, to its degranulation with release of mediators (histamine, serotonin, leukotrienes, thromboxane, PAF) with subsequent bronchoconstriction and production of viscous mucus. As to adrenergic factors, a block of beta-adrenergic receptors and reduced adrenal function is involved. As to non-adrenergic factors an increased sensitivity of the parasympathetic--vagus is involved which conditions bronchoconstriction and hyperkrinia. From the clinical aspect extrinsic (atopic) and intrinsic (cryptogenic) asthma bronchiale can be differentiated. The former is encountered more frequently in childhood and adolescence, in subjects with a positive family-history, high IgE and positive skin tests and a known allergen. The latter type of a.b. is found in adolescence, in subjects with a negative family-history, with eosinophilia; it is conditioned by infection (e.g. chronic bronchitis), strain, cold and takes a dangerous course (aspirin). As to the course, attacks of a.b. are involved with a symptom-free interval (extrinsic a.) easily controlled by treatment. Then there is the chronic form with a variable course and the necessity of permanent treatment. Status asthmaticus is in recent years with increasing frequency the cause of death and thus calls for maximal treatment. It is the third most serious form of a.b. Assessment of arterial blood gases is very important as a check of treatment as well as from the prognostic aspect (cross-over intubation). From the differential diagnostic aspect we must consider the asthmoid component in chronic bronchitis, pulmonary embolism, left-sided cardiac failure, tracheal or bronchial compression by an aortal aneurysm, tumour. The differential diagnosis is not always easy.


[Self-treatment and self-monitoring in patients with bronchial asthma]. Regular assessment of the peak expiratory flow (PEF), which after proper instruction, the patient can do himself is important for evaluation of the activity of bronchial asthma. It is, however, essential to assess the optimal PEF values of every individual. For control of self-treatment it is important to know the daily variations of PEF and the degree of reversibility of bronchospasm after inhalation of a beta 2-adrenergic substance. Inadequate reversibility of bronchial obstruction despite repeated inhalation of a beta 2-adrenergic substance is usually caused by inflammation. Depending on the clinical status and changes of PEF the patient can, if properly instructed, start corticosteroid treatment in case of acute deterioration or increase the corticosteroid doses in case of subacute deterioration of the condition. Follow-up of PEF is important also for self-management in case of clinically latent deterioration and during maintenance treatment.


[Climate therapy, rehabilitation and psychotherapy in bronchial asthma]. The authors explain the principle of effectiveness as regards treatment of bronchial asthma (AB) in the climate of the Tatra mountains. The most important place is held by elimination of noxious substances from the patient's environment which is comparable with the eliminations test. The second place is held by factors of a medium stimulating climate which calls for adaptation of the organism. This happens during the three-week acclimatization stage which acts as non-specific therapy. The result of climatotherapy is an increased immunological resistance, hardening, reduced bronchial hyperreactivity and improved life of asthmatic patients. Supplementary treatment comprises respiratory rehabilitation and psychotherapy. The aim of rehabilitation is active participation of the patient in treatment, adequate type of respiration and better tolerance of physical strain. The purpose of psychotherapy is to help the patient to overcome fear of AB, induce a change of lifestyle and regime. After comprehensive institutional treatment the patients are prepared for self-supporting ambulatory treatment. Under institutional conditions antiasthmatic treatment can be discontinued in as many as 24% of asthmatic patients and reduce substantially the administration of inhalatory beta-adrenergic substances, as demonstrated by the authors on 1725 asthmatic patients.


[Correct inhalation technique--an integral part of rational treatment of bronchial asthma]. In the rational treatment of asthma bronchiale in recent years a marked increase can be observed as regards prescription of beta-2-agonists and glucocorticoids. They are administered almost exclusively from metered dose inhalers (MDI) with an adjustable valve. Almost half the users do not know the correct inhalation technique. Unless that is used, the effect of drugs is markedly reduced. The author deals therefore in his review in detail with all aspects of a correct inhalation technique; above all he emphasizes slow inhalation with subsequent breath retention which is the only way how to achieve maximum penetration of particles to the final branches of the bronchial tree. The author mentions also spacers which improve in some patients the effectiveness of aerosol treatment.


[Fructose metabolism disorders and infusions]. The authors give an account of views regarding the use of non-glucose energy sources in parenteral nutrition during the immediate post-load period/serious operations, severe injuries). Attention is devoted to the metabolic pathway of fructose and its disorders. In hereditary fructose intolerance an infusion of D-fructose or D-glucitol (= sorbitol) can induce life threatening hypoglycaemia (unless glucose is administered concurrently). According to some views, in subjects with this intolerance the organism is threatened also by hepatic and renal failure; their development may be independent on hypoglycaemia. Fructose and D-glucitol (sorbitol) therefore should not be administered by the parenteral route. This view is supported by cases where hereditary fructose intolerance could not be revealed from the case-history and clinical manifestations. Some countries have already eliminated fructose and D-glucitol (sorbitol) from their pharmacopoeias.


[Synergic joint diagnostics].

[Synergic joint diagnostics]. The author emphasizes the necessity to use all clinical and paraclinical examination methods in rheumatology to assess an early and correct diagnosis of rheumatic diseases. She emphasizes the importance of examination of the articular punctate and importance of the synoviogram in differential diagnostic considerations. The author reflects also on the importance of the frequently omitted unpretentious examination method--needle biopsy of the joints.


[Diagnostic and treatment problems in malignant neoplasms]. The article gives the comparative estimation between the state of oncological aid in the system of the civilian health care and military medicine. The authors analyse the most frequent defects in diagnosis and treatment of malignant new-growths. The article focuses the attention of physicians on an early diagnosis of malignant new-growths, necessity to improve their oncology-oriented skill, and render an adequate oncological aid to the servicemen.


[The transpubic surgical approach and experience with using it to treat posttraumatic strictures of the posterior urethra]. Anatomic researches on 15 cadavers of male adults were conducted to study the transpubic access to the urethra and substantiate its possible application for the treatment of the urethral strictures. The authors make a comparative evaluation of transpubic and perineal methods of the access. As for basic indices (the depth of operative wound, direction and the angle of the operative axis inclination), the transpubic method of access has a number of advantages over the perineal access, and is an optimal one for surgical interference on the urethra. The transpubic access was applied on 21 patients who were operated for strictures or obliterations of the urethra. In all the patients the transitivity of the urethra was restored. No complications were marked.


[Anesthesia of the cervical plexus in surgical interventions on the neck and its organs]. The author proposes a new method for anesthesia of neck plexus, which is seen to be more safe, has reliable points of reference, and is administered by "one-touch" injection. The article gives a description of this method, results of its clinical application, indications and counter-indications. The anesthesia of neck plexus was applied on 71 patients. No complications were marked. This method makes it possible to produce an adequate anesthesia in vast operations on neck and its organs.


[The performance quality of a flight trainer operator under conditions of heat discomfort]. The studies were conducted on 5 sound operators, age 26-44. The flight simulator was placed into a heat chamber with temperature range from 25 degrees C to 60 degrees C. In these conditions the operators had to withstand pitching and rolling in "horizontal flight" within 6 min. The piloting performance on simulator was conducted by the operators every 10 min. per one hour. 48 tests were carried out. The studies have shown the phase character in roll error at the temperatures of 60 degrees C. The authors make a conclusion that the moderate hypothermia could optimize the operator's performance, and the deep one could worsen it.


[The stability and quality control of ditilin preparations (a review of the literature)]. In aqueous solutions dithylinum decomposes with formation iodine, choline, succinic acid and its monoether. The rate of decomposition depends on the conditions of storage, and also upon the concentration and ion force of solution, existence of ion metals and some other factors. The article proposes methods for identification and quantitative analysis of dithylinum and the products of its hydrolysis. The requirements imposed for storage or transportation of dithylinum solutions: not frost and temperature level not higher than 5 degrees C.


[A low-frequency alternating magnetic field and its combination with radon baths in juvenile rheumatoid arthritis]. Children suffering from juvenile rheumatoid arthritis (JRA) (n-132) were exposed to low-frequency variable magnetic field. Therapeutic response registered consisted of analgetic and anti-inflammatory effects most pronounced in 14-19 mT regimen. The addition of radon baths to the above exposure resulted in higher effectiveness of the treatment due to involvement of pathogenetic JRA mechanisms.


[A new method for treating rheumatoid arthritis patients by electrophoresis using mefenamic acid]. The paper provides clinical and experimental reasoning for application of a new treatment for rheumatoid arthritis (RA) implying electrophoresis of an anti-inflammatory drug mefenamic acid from dimexide solution. Complete and partial responses registered in 125 patients, reached 75%. With the new method it is possible to relieve pain, correct immunity and stop inflammation. The best effect was shown in an inactive disease and in activity phases I and II in adjuvant use of the method.


[The correction of functional disorders of the bile-secreting system by using laser radiation]. He-Ne laser irradiation of biologically active points and infrared laser irradiation of the liver were employed to improve gallbladder and sphincter functions, bile production and biochemistry, respectively, in a total of 57 patients with biliary dyskinesia presenting as hypokinetic dyskinesia of the gallbladder, hyperkinetic dyskinesia of the sphincter of Oddi or the combination of the two affections. Simultaneous use of the two kinds of laser irradiation appreciably shortens treatment duration, abolishes biliferous dysfunction, reestablishes physiological balance of bile components in case of its initial lithogenic potential.


[The phonophoresis of solutions of a "dry" mud extract in the therapy of patients with chronic gastritis]. The study of stomach morphology and function in chronic gastritis treated with phonophoresis of dry mud extract solutions demonstrates a stimulating effect of the treatment on acid production. A positive response was also registered on the part of the structure of gastric mucous lining and functional activity of this epithelium.


[The modelling of the cavitation processes during the focusing of the shock wave in an electrodynamic lithotriptor]. The paper reports an experimental technique and the results obtained in the study of cavitation arising in focusing the shock wave of electrodynamic lithotriptor. The aim of the above study was to specify mechanisms of soft tissue lesions during destruction of nephroliths with lithotriptor impulses. Cavitation regions were found along the axis of the generator focusing system and at its outgoing sites as a result of the boundary expansion wave. This phenomenon by the body margin is attributed to transformation of a positive pressure impulse into the tension impulse. As the shock wave pressure impulse is much more significant than the pressure impulse of the boundary expansion wave it is most probable that cavitation-induced lesions appear at the site of the wave exit from the body.


[The action of a pulsed magnetic field on the electrical resistance of the skin]. The skin of 32 rabbits and 10 patients (7 males and 3 females aged 32-48) was exposed to impulse magnetic field (IMF) with intensity of 1.0-1.5 T and frequency of 45 paired impulses a minute. The 5-minute exposure resulted in a 50% decrease in the skin electrical resistance both in patients and animals. On aftertreatment minute 2 the resistance started recovering and returned to the baseline on minute 6 in animals and 4 in patients. Changes in electrical resistance of the skin are attributed to emergence of IMF-related electrical induction.


[The effect of korinfar and anaprilin on lipid peroxidation and the antioxidant system in hypertension patients]. Changes of lipid peroxidation products and activity of the antioxidant system during corinfar and anaprilin treatment were studied in 36 patients with hypertensive disease (stage II). A decrease of the content of malondialdehyde and dien conjugates was revealed in the blood of these patients after a course of treatment with these agents. Simultaneously, the antioxidant protection of the blood increased: the concentration of reduced glutathione increased, the activity of glutathione peroxidase rose. The changes of oxidated glutathione were not clear. It is suggested that such character of the effect of corinfar and anaprilin on the processes of lipid peroxidation is the result of a direct effect on lipid peroxidation products and also compensatory activation of enzymatic reactions of restoration of natural cellular antioxidants as well as enzymatic system directly utilizing lipoperoxides.


[The evaluation of gallbladder contractile function and the ultrasonic signs of chronic noncalculous cholecystitis]. A correlation of the clinical picture of the disease, results of ultrasonic examination (USE) of the gallbladder and laboratory findings in 120 patients with chronic noncalculous cholecystitis has been evaluated. The contractile function of the gallbladder by USE was carried out 25 minutes after intake of 30 ml of olive oil. A correlation has been established between the severity of the clinical picture and echoscopic signs in chronic cholecystitis. The most frequent symptoms of chronic cholecystitis as evaluated by USE were association of thickening and hardening of one of the gallbladder walls and non-homogeneity of the gallbladder. The olive oil test is important in the ultrasonic examination.


[The evaluation of the results of the bicycle ergometry training of students with an inactive phase of rheumatism]. 157 students with compensated mitral insufficiency in inactive rheumatism exercised on bicycle ergometer. Matched controls did not exercise. The analysis of cardiorespiratory parameters showed advantages of the training. Being statistically significant, these advantages support introduction of the method into wide practice.