Ultrastructural changes in hepatocytes of precision-cut rat liver slices after incubation for 24 and 48 hours

Hepatocytes of precision-cut rat liver slices were studied by means of transmission electron microscopy after long-term incubation (24–48 h) in comparison with freshly prepared slices, indicating reversible and irreversible intracellular alterations of the cells. After 24 h incubation the morphological image in transversal sections of slices is characterised by a central zone of damaged and necrotic cells flanked by two to several superficial layers of viable cells. This is typical of a diffusion gradient of oxygen tension and nutrient content from the surface to the centre of the slices. In adapted cells on the surface of the slices we observed an organelle-free layer of fine granular material in the apical cytoplasm followed by parallel oriented stacks of rough endoplasmic reticulum near by. Mitochondria of essentially normal appearance in adapted cells did not contain flocculent densities, which were observed in damaged cells only. The cytoplasm of parenchymal cells consisted of defined areas of clear cytoplasmic material containing numerous branching tubular profiles of smooth endoplasmic reticulum, presumably in the regions with depleted glycogen aggregates. Subcellular signs of necrosis are destroyed mitochondria, dilated endoplasmic reticulum free of ribosomes and clumping of chromatin in the nucleus of hepatocytes. No appreciable differences of the cell organelles were observed between 24 and 48 h of incubation, but the incidence and intensity of signs of necrosis increased with the duration of incubation and the thickness of the slices. The process of these changes may reflect the phenomenon of cellular adaptation and of hypoxic cellular injury in the periphery and the centre of the slices, respectively.     

Exposure to extremely low-frequency electromagnetic fields improves social recognition in male rats

The effect of exposure to low-frequency electromagnetic fields (ELF EMFs) on social recognition was studied. The test was based upon a comparison between two encounters of an adult rat and a conspecific juvenile, separated by an interexposure interval (IEI). The exposure to ELF EMF of 1 mT intensity during 2 h for 9 days increased the duration of short-term memory of adult male Wistar rats up to 300 min. These data indicate, for the first time, that ELF EMF improves social recognition memory in rats.     

Rewarding effects of the optical isomers of 3,4-methylenedioxy-methylamphetamine ('Ecstasy') and 3,4-methylenedioxy-ethylamphetamine ('Eve') measured by conditioned place preference in rats

3,4-methylenedioxy-methylamphetamine (MDMA) (‘Ecstasy’) and its analogue 3,4-methylenedioxy-methylamphetamine (MDE) (‘Eve’) are well known illicit street drugs mainly abused by young people. In spite of the actual research going on, the classification of their abuse potential remains unclear. Since secondary reinforcers are the main factors responsible for craving and relapse, the aim of our study was to assess the potency of MDMA and MDE in a second order reinforcement paradigm, i.e. conditioned place preference (CPP). For the general assessment of our study conditions, we compared MDMA with amphetamine. Unexpectedly, no significant CPP for MDMA was found in contrast to amphetamine. Detailed analysis of current literature led us to the working hypothesis that social environment is crucial for the development of CPP. In a subsequent experiment we tested the influence of housing conditions on CPP using MDMA and demonstrated that isolated animals show significant CPP compared to group-housed ones. In order to better understand the rewarding mechanisms of Ecstasy-derivatives, we tested both the racemic drugs and the pure isomers in the CPP paradigm. Both MDMA's optical isomers and racemic MDMA showed significant CPP without notable differences, while MDE and its isomers completely failed to show any significant CPP. In conclusion, the mechanism by which MDMA induces addiction is much more complicated than assumed so far and more pronounced in isolated animals. The fact that both optical isomers of MDMA led to CPP implies that at least two pathways by which MDMA induces craving behaviour exist.     

Interference between velocity-dependent and position-dependent force-fields indicates that tasks depending on different kinematic parameters compete for motor working memory

Humans demonstrate motor learning when exposed to changes in the dynamics of movement or changes in the visuomotor map. However, when two opposing dynamic transformations are learned in succession, the memory of the first is overwritten by learning of the second; the same is true for two opposing visuomotor rotations. This retrograde interference is not seen for all combinations of transformations, however. When a dynamic transformation is learned subsequent to a visuomotor rotation, the presence or absence of interference appears to depend crucially on the structure of the dynamic task: a force-field dependent on the position of the hand produces interference, whereas an inertial load applied lateral to the hand does not. To explain these results, it has been hypothesized that two transformations can be learned without interference if they depend on two different kinematic parameters of movement (such as position and velocity of the hand). Here we demonstrate, contrary to this hypothesis, interference between a dynamic transformation that depends on the position of the hand and one that depends on its velocity. However, the interference was found to be incomplete, supporting the view that the ability to retain motor memories for different tasks depends on the degree to which their representations conflict in working memory.     

社交回避与苦恼量表在学生群体中的信效度研究

社交焦虑正日益受到我国心理学与精神病学界的关注 ,对社交焦虑本质的探讨、临床评估以及疗效测评等都需要有效可靠的工具。社交回避与苦恼量表 (Socialavoidanceanddistressscale ,SAD)是国外应用较多的量表之一[1] ,它是Watson与Friend于 196 9年建立在大学生样本上的测量社交焦虑状态的量表 ,用于评估回避社会交往的倾向以及身临其境时的苦恼感受。作者采用“理性分析”法 (rationalanaly sis)建立相关的条目[2 ] 。量表建立初期至今 ,不断有人对其进行信效度考证 ,大都认同其具有良好的测量学品质[3,4 ] ,故在国外被广泛地用于焦虑研…     

Influence of interaction force levels on degree of motor adaptation in a stable dynamic force field

Studies have shown that the point-to-point reaching movements of subjects seated in a dark, rotating room demonstrate errors in movement trajectories and endpoints, consistent with the direction of the Coriolis force perturbations created by room rotation. Adaptation of successive reaches and the presence of postrotation aftereffects have indicated that subjects form internal models of the Coriolis field dynamics in order to make appropriate movement corrections. It has been argued that these findings are inconsistent with predictions of peripheral stabilization assumed in equilibrium-point models of motor control. A possibility that has been raised, however, is that the Coriolis field findings may in fact stem from changes in control commands elicited due to the magnitude and destabilizing nature of the Coriolis perturbations. That is, it has been suggested that a perturbation threshold exists, below which central reactions are not necessary in order to maintain movement stability. We tested the existence of a perturbation threshold in normal-speed reaching movements. Twelve normal human subjects performed non-visually guided reaching movements while grasping a robotic manipulandum. The endpoints and trajectory deviations of their movements were measured before, during, and after a position-dependent force field (similar to a Coriolis field in terms of the time history of applied forces) was applied to their movements. We examined the responses to a range of perturbation field strengths from small to considerable. Our experimental results demonstrated a substantial adaptation response over the entire range of perturbation field magnitudes examined. Neither the amount of adaptation after 5 trials nor after 25 trials was found to change as disturbance magnitudes decreased. These findings indicate that there is an adaptive response even for small perturbations; i.e., threshold behavior was not found. This result contradicts the assertion that peripheral stabilization mechanisms enable the central controller to ignore small details of peripheral or environmental dynamics. Our findings instead point to a central dynamic modeler that is both highly sensitive and continually active. The results of our study also showed that subjects were able to maintain baseline pointing accuracies despite exposure to perturbation forces of sizeable magnitude (more than 7 N).     

Visual field deficits in cats reared with cyclodeviations of the eyes

Summary Visual fields of ten cats which had one or both eyes rotated at 8 days of age were measured by two forms of perimetry and compared to visual fields of two normal cats and of four cats with monocular rotations at 16 days, 3 months or 6 months of age. All animals showed excellent localization of visual stimuli and responded to the actual location of stimuli in space rather than to the retinal locus normally associated with that location. In cats with monocular rotations, the field of the normal eye was always normal, extending from 90 ° ipsilateral to 30 ° contralateral. Cats with rotations of one eye at 3 or 6 months of age had essentially normal fields in the rotated eye as well, while cats with surgery at 8 or 16 days had restricted horizontal fields. They responded only to stimuli in the ipsilateral hemifield; they were blind in the contralateral hemifield. Their superior and inferior visual fields were normal. The field deficits related consistently to visual field coordinates and not to the angle or direction of rotation. In cats with binocular rotations the visual field of at least one eye extended across the midline. Thus, the extent of the field depended upon sensorimotor experiences of the cat both before and after surgery. It is argued that these monocular field deficits have a central origin, not a retinal one.When tested with both eyes open, seven of 14 experimental animals did not respond throughout the visual field seen by each eye alone. The total visual field with both eyes open was less than the sum of the two monocular fields; greatest losses were most pronounced in the extreme periphery of the field ipsilateral to the rotated eye. Since changes in eye position (e.g., convergence during bincocular viewing) were not observed, it is suggested that the binocular losses indicate suppression of the deviated eye which has a central origin.All animals were tested for visual following, visually-triggered extension (placing), and visually-guided reaching. Cats which had been routinely encouraged to use the rotated eye(s) by occlusion of the other eye showed skilful performance within a few weeks after surgery as previously reported by Peck and Crewther (1975), Mitchell et al. (1976) and others. In contrast, two cats reared with both eyes open after unilateral rotation in infancy were profoundly handicapped, as previously reported by Yinon (1975, 1976).This research was supported by Grant NS 14116 from the US Public Health Service     

吸毒者的社会支持及与心身健康水平的相关分析

毒品滥用已成为严重社会问题 ,并已引起医学界、心理学界及社会各界的关注。吸毒者的吸毒行为除与他们自身心理特征有关外 ,还与许多因素有关。如失业、缺乏家庭温暖、精神空虚、孤独 ,对生活失去热情和信心等。研究认为 ,社会支持系统不良是导致多种心理卫生问题的重要原因之一 ,也是吸毒成瘾及复吸的主要原因[1,2 ] 。本研究运用社会支持量表和症状自评量表对一组吸毒者的社会支持状况及与心理健康的关系作初步研究 ,旨在为吸毒者实施心理治疗及作戒毒后回归社会的跟进服务提供参考。1　资料与方法1.1　调查对象1.1.1　吸毒组　选择长沙市…     

Effects of social factors on adrenal weight and related physiology of Macaca fascicularis

Increased adrenal cortical activity and hypertrophy of adrenal glands associated with defeat and social subordination have been reported frequently in small mammals; these adrenal changes have been linked to impairments in immune response, glucose metabolism and reproductive performance. Similar studies in primates have produced variable results. The current study was undertaken to illuminate the effects of social status on the adrenal gland and to examine concurrent effects of social variables on other physiological systems in Macaca fascicularis, in an initial exploration of the hypothesis that high and low social status have different physiological consequences. Sixty adult male M. fascicularis were housed in social groups of n = 5, under either stable or unstable social conditions. It was found that subordinate animals had heavier adrenal glands and somewhat higher plasma glucose concentrations than dominants. In contrast, dominants had higher blood pressure and worsened atherosclerosis, under some conditions, than subordinates. These data appear to offer preliminary support for Henry and Stephen's hypothesis of differential arousal of dominant and subordinate animals.     

Establishment of social rank among grouped male mice: relative effects on circulating FSH, LH, and corticosterone

Previously-isolated, adult, CF-1 male mice were grouped four per cage, killed after periods of time ranging from one hour to 14 days, and their plasma assayed for corticosterone, FSH and LH. Dominant and subordinate ranks were easily separable after 24 hr for comparison with each other and with isolated controls that were also killed throughout the 14-day experimental period. The one hour responses to grouping, during which all males were fighting intensely to establish rank, included a 5–6 fold increase in plasma corticosterone and concurrent depressions in circulating gonadotropins, 19% for FSH and a dramatic 94% for LH. Plasma corticosterone returned to baselevels between Days 1 and 3 in the case of dominant males and between Days 3 and 6 for subordinates. Adaptation was also observed for FSH in the plasma of dominants but later than that occurring for corticosterone. Plasma FSH in subordinates and circulating LH among both relative ranks were still depressed at the end of the 14-day period. A reciprocal relationship between adrenocortical activity and gonadotropin secretion was thus observed only during the early phases of dominance-subordination establishment; thereafter, secretory patterns for these three hormones functioned independently. Seminal vesicles were little affected by grouping but mean preputial weight increased markedly and progressively among dominant males and decreased with time in subordinates.