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     

Community stressors, mediating conditions and wellbeing in urban neighborhoods.

Individual and community measures of stress are related to the presence of depression/demoralization symptoms (Feeling Bad), to positive Wellbeing (Feeling Good) and to the combination of these two (Wellbeing), in an urban sample of 549 adults. The mediation and moderation of these effects by indicators of social support, evaluation of status, and belief variables intended to measure aspects of individual coping tendencies are examined and tested. The findings suggest the absence of moderating effects of any of the support and coping variables on each stressor or on the effects of stressors on Feeling Bad, Feeling Good, and Wellbeing. A number of the variables do, however, have significant main effects, and thus appear to operate directly on the dependent variables, regardless of the presence or level of stress. Differences between apparent effects on Feeling Good and Feeling Bad and the increase in effects for the combination measure are discussed.     

Lack of shared lymphocyte-stimulating determinants between H-2I and HLA-D/DR using mouse primed lymphocyte typing cells

A number of anti-H-2 alloantisera containing antibody reactive with I region gene products (Ia) of the major histocompatibility complex cross-react with determinants expressed by human peripheral blood B lymphocytes. Such data have led to the conclusion that Ia and DR antigens share cross-reacting determinants. We have attempted to generate mouse primed T lymphocyte populations specific for defined I region gene product determinants which concomitantly recognize DR determinants on human peripheral blood leukocytes in primed lymphocyte typing (PLT) analysis. Mouse PLT cells were generated in primary MLC using strain combinations identical to those in which positive mouse/human cross-reacting antisera have been obtained. The resulting PLT cells exhibited strong, yet specific, secondary MLC responses against mouse cells expressing the Ia determinants used as the primary stimulus. In contrast, when examined on panels of human peripheral blood leukocytes, no reactivity was detected. This lack of cross-reactivity suggests that mouse T cells primed toward Ia determinants do not regularly recognize cross-reacting determinants of DR or D-associated antigens expressed on human PBLs. Consequently, mPLT cells are not a useful reagent in defining HLA-D region polymorphism.     

Supraependymal cells in the third ventricle of the neonatal rat

Supraependymal cells in the third ventricle of neonatal male and female rats were examined with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Supraependymal cells in the third ventrical of adult male rats were also studied with SEM. Many neonate supraependymal cells were round to oval in shape and exhibited varying degrees of surface irregularity. Small finger-like processes or narrow pseudopodia projected from the cell bodies over the underlying ependymal cells. Some neonatal supraependymal cells exhibited flattened cell bodies with broad pseudopodia and few surface irregularities. TEM revealed a variety of cell profiles. Prominent within the cytoplasm of many supraependymal cells were lysosomes, smooth and coated vesicles suggesting pinocytosis, subplasmalemma vacuoles, and occasional lipid droplets. The morphological characteristics of neonatal supraependymal cells suggested they were mononuclear phagocytes. Adult supraependymal cells exhibited more pleomorphic cell shapes with numerous cell processes, varying widely in size and shape, and often extending over the ventricular surface for considerable distances. These observations, in combination with previous studies by other investigators, suggest that some adult supraependymal cells may also be phagocytic in nature. The differences in morphology between adult and neonatal supraependymal phagocytes may relate to the differing third ventricle environment between adult and neonates and/or differences in the origin of the phagocytes with age.     

Discharge patterns of neurons in the rostral superior colliculus of cat: activity related to fixation of visual and auditory targets

Neurons in the rostral superior colliculus (SC) of alert cats exhibit quasi-sustained discharge patterns related to the fixation of visual targets. Because some SC neurons also respond to auditory stimuli, we investigated whether there is a population of neurons in the rostral SC which is active in relation to fixation of both auditory and visual targets. We identified cells which were active with visual fixation and which continued to discharge if the fixation stimulus was briefly extinguished. The population of neurons exhibited similar discharge characteristics when the fixation stimulus was auditory. Few neurons were significantly more active during fixation of visual targets than during fixation of auditory targets. Most fixation neurons showed a diminished discharge rate during spontaneous (self-generated) saccadic eye movements away from a visual fixation stimulus, regardless of the direction of the saccade. this diminished discharge rate (or pause) typically began, on average, 12.2 ms before saccade onset and the duration of the pause was Ionger than the duration of the saccade. These observations are consistent with the hypothesis that increased discharge of these neurons is related to active fixation and that reductions in their activity are important for the generation of saccades. However, the lack of a precise relationship between pause duration and saccade duration implies that these neurons would be unlikely to project directly to the saccadic burst generator. The mean interval from the beginning of the pauses of fixation neurons to be beginning of the saccades away from fixation targets is also shorter than has been found in brainstem omnipause neurons. By analogy with the concept of a receptive field, agaze position error field depicts the range of gaze position error for which a cell is active. Although fixation neurons appear to encode the magnitude and direction of the error between visual targets and the visual axis, visual error fields at the end of fixating eye movements were significantly larger than those at stimulus onset. For auditory stimuli, this difference was not significant. These observations are compatible with a number of recent experiments indicating that neural signals of eye position are damped or delayed with respect to current eye position.     

An alternative perspective to the immune response in autoimmune exocrinopathy: induction of functional quiescence rather than destructive autoaggression

Sjögren's syndrome is characterized by dryness of the eyes and the mouth due to mononuclear cell infiltration of the lacrimal and salivary glands. The aetiology is unknown but autoimmunity is considered to play a significant role in the pathogenesis. Recent studies have focused on the fact that tear and salivary flow involves an entire functional system that includes the mucosal surfaces with adnexes (the site of inflammation), efferent nerve signals sent to the midbrain (lacrimal and salivary response region), and afferent neural signals from the brain to the acinar/ductal epithelial structures in the gland. Mononuclear cell infiltration in exocrine glands can lead to glandular destruction, suggested to be mediated through apoptosis. However, the functional impairment of exocrine glands could be regulated by cytokines and/or antibodies against the muscarinic M3 receptor by inhibiting the neural stimulation of the residual glands. This review discusses the possibility that the pathogenesis of Sjögren's syndrome comprises aberrant immune-mediated neuro-hormonal events.     

Prevalence and Associated Factors of Sarcopenia in Singaporean Adults—The Yishun Study

ObjectivesTo describe the normative values of sarcopenia among community-dwelling adults (≥21 years of age); compare the prevalence of sarcopenia using Asian Working Group for Sarcopenia criteria, 2014 (AWGS2014), Asian Working Group for Sarcopenia criteria, 2019 (AWGS2019), and European Working Group on Sarcopenia in Older People criteria, 2018 (EWGSOP2) guidelines; and identify factors associated with sarcopenia.DesignParticipants were recruited through random sampling. Sarcopenia assessments were performed using a dual-energy x-ray absorptiometry scan (muscle mass), handgrip test (muscle strength), and usual walking test (physical performance). Questionnaires were administered to evaluate lifestyle and cognition.Setting and ParticipantsIn total, 542 community-dwelling Singaporeans were recruited (21?90 years old, 57.9% women).MethodsWe assessed anthropometry, body composition, and questionnaire-based physical and cognitive factors, and estimated sarcopenia prevalence according to the AWGS2014, AWGS2019, and EWGSOP2 recommendations, and examined associations using logistic regression.ResultsAccording to AWGS2019, the Singapore population-adjusted sarcopenia prevalence was 13.6% (men 13.0%; women 14.2%) overall, and 32.2% (men 33.7%, women 30.9%) in those aged 60 years and above. The cut-offs derived from young adult reference group for low appendicular lean mass index were 5.28 kg/m2 for men and 3.69 kg/m2 for women (lower than AWGS recommended cut-off); for gait speed it was 0.82 m/s, (AWGS2019 recommended cut-off 1.0 m/s, AWGS2014 cut-off was 0.8 m/s); and for handgrip strength it was 27.9 kg/m2 for men and 16.7 kg/m2 for women (close to AWGS2019 recommendation). Age, sex, marital status, alcoholism, physical activity, body mass index, waist circumference, and global cognition were associated with sarcopenia (P < .05).Conclusions and ImplicationsThis is the first study to provide reference values of muscle mass, strength, and gait speed across the adult lifespan of Singaporeans. Using AWGS2019 criteria, sarcopenia is prominent in older age (32.2% in ≥60 years old), but it is already nontrivial (6.9%) among young and middle-age persons. Multidomain lifestyle modifications addressing muscle strength, cognition, and nutrition over the adult lifespan are important to delay the development of sarcopenia.