Biomedical subjects
Publications and source records attributed to S Wolf.
Catalase may provide protection against photochemical action of superoxide radicals and hydrogen peroxide. The authors tried to measure its activity in freshly enucleated calf eyes before and after argon laser irradiation. It was established by iodometric titration that catalase activity was reduced after irradiation in vitreous and in purified catalase solution, but not in the lens.
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The early physiopathologic responses to transection of the cervical spinal cord (C-4) were studied in the experimental animal. After transection, increases were seen in the mean arterial pressure, pulmonary capillary wedge pressure, intracranial pressure, brain water, blood--brain barrier permeability, and extravascular lung water with a marked decrease occurring in cerebral blood flow. Pretreatment with an alpha-adrenergic blocker, phentolamine (Regitine Ciba-Geigy Corp.), followed by transection blocked the rise in mean arterial blood pressure and pulmonary capillary wedge pressure but did not affect the increases in intracranial pressure, brain water, blood--brain barrier permeability, and extravascular lung water and decreases in cerebral blood flow. Transection of the cervical spinal cord initiates a complex series of events involving intracranial compliance and pulmonary permeability, placing both brain and lungs at risk.
The clinical application of TV fluorescein angiography with subsequent image analysis as performed on a patient with familial Mediterranean fever (FMF), who was suffering from an arterial branch occlusion, is discussed. In addition, the diagnostic relevance of rheologic parameters to the diagnostic evaluation of retinal circulatory disorders is emphasized.
Thirty years before Beaumont's publication of his observations of Alexis St. Martin, Pierre Jean Georges Cabanis, a brilliant but now little-known French physiologist, reported clinical data on digestive disturbances that accompany emotional upset. With extraordinary prescience he distinguished emotional states associated with the suppression of digestion from those that were accompanied by accelerated gastric secretory and motor function. However, Beaumont was the first to document the inhibitory effects on digestion by direct observation of the stomach. Later, others documented the excitatory effects, provided further detail concerning emotional states, and began to identify neuronal pathways and humoral mechanisms responsible for the phenomena. The integrative mechanisms in the brain that link life experience to gastric responses have come under study recently; the process has turned out to be immensely complex. Several neurotransmitters have been identified that subserve the facilitatory and inhibitory mechanisms converging on the efferent neurons that ultimately elicit patterns of visceral and general behavior. However, investigations of cognitive and emotional responses to stressful experiences have been largely neglected in humans. Although sophisticated methods and instruments exist that record in a noninvasive fashion a whole spectrum of gastric behavior, such studies are now out of fashion. To fully explore the stomach's link to the brain, research on the entire human organism must be revived.
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We examined the relationship between changes in heart rate and the measured QT interval of the electrocardiogram in healthy subjects after exercise and during breath holding, hyperventilation, the dive reflex, the Valsalva maneuver, and the cold-pressor test. The tachycardia of exercise was accompanied by the familiar shortening of the QT interval, but substantial heart rate changes encountered in other more "sedentary" maneuvers were accompanied by very small changes in QT. Calculating the corrected QT in the latter instances, therefore, yielded spurious results. The data suggest very little, if any, direct effect of heart rate on the QT interval. The length of the interval in healthy subjects appears to be determined largely by reflexly elicited discrete autonomic influences. Those associated with exercise result in QT shortening but, during neurally mediated cardiovascular adjustments that do not involve exercise, QT is maintained within narrow limits.
A new experimental method is described which permits estimation of flow ability of blood: measuring the yield shear stress with the erythrocyte-stasis-meter (ESM). This method is based on the phenomenon that pathological blood under low pressure behaves like a solid body. Knowing the pressure difference at the transition point from solid to fluid behavior and the geometry of the channel, the yield shear stress can be calculated.
We present a system consisting of a slit lamp stereomicroscope and an adapted video system for the examination of the conjunctival microcirculation. This system permits measurement of the flow of erythrocytes in the vessels of the bulbar conjunctiva. We present values obtained from clinically normal individuals under normal conditions and under conditions of hyperperfusion.
Fluorescence angiograms of the retina were performed on 12 healthy, adult subjects between the ages of 20 and 52 years with a 30 degrees fundus camera (C. Zeiss), a low-light TV camera and a video recorder. Characteristic blood-flow parameters for the retina were obtained from the video recording using the picture-analysis system (Mikrovideomat 3, C. Zeiss). These included: the arm-retina time (ART), the arteriovenous passage time (AVP) and the arterial contrast-medium velocity (ACMV). Normal values for these parameters were derived for the four retinal quadrants and then discussed. In addition, the filling characteristics of venules were measured and discussed.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
The creatine concentration of red blood cells and plasma in 44 children with chronic renal failure was studied and found to be significantly higher than in healthy children of comparable age. The creatine concentrations of the 31 hemodialyzed children surpassed those of the 13 conservatively treated patients by 30%. A statistically significant correlation was demonstrated between the serum creatinine level and the creatine concentrations in red blood cells. During hemodialysis the plasma creatine concentration decreases by half and reaches the predialysis values within 42 h after the end of dialysis, whereas the creatine concentration of the red cells does not change during a 4-5-h hemodialysis. With increasing number of hemodialyses the creatine concentration of red cells rises, suggesting an improvement of erythropoiesis.