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Biomedical subjects

B A Berkowitz

Publications and source records attributed to B A Berkowitz.

At least 127 records · Page 7Linked to original sources
PubMed1972

Resistance of noradrenaline in blood vessels to depletion by 6-hydroxydopamine or immunosympathectomy.

1. The degree of the decrease in the noradrenaline concentrations caused by 6-hydroxydopamine or immunosympathectomy was different in different areas of the cardiovascular system.2. In rats or guinea-pigs 6-hydroxydopamine depleted the noradrenaline content of the heart by 90%, of the mesenteric vein by 80% and of the mesenteric artery and aorta by 30-60%. Immunosympathectomy elicited a 70% reduction in the cardiac noradrenaline but only a 50% reduction in the noradrenaline of the blood vessels of the rat.3. The tyrosine hydroxylase activity of the heart, blood vessels, or adrenal glands was not significantly altered 2 weeks after 6-hydroxydopamine. Nor was the monoamine oxidase activity in heart or blood vessels changed.4. The inconsistent ability of both 6-hydroxydopamine and immunosympathectomy to abolish experimental hypertension may be due to the partial persistence of noradrenaline and functional sympathetic nervous system activity in the blood vessels.

Adrenal Glands↗
PubMedDate not supplied

Perfluorocarbon temperature measurements using 19F NMR.

Measuring the T1 of the fluorine resonances of perfluorocarbons (PFC) is a unique method for monitoring oxygen tension in vivo. However, because T1 is also temperature sensitive, error in the pO2 determination due to animal-to-animal temperature variation may arise. Pathophysiologic conditions, such as ischemia, where temperature is not known a priori may also introduce error. Thus, measuring the PFC temperature is clearly desirable in order to correct for tissue temperature variations during the pO2 determination. Because the fluorine chemical shift of various fluorinated compounds has a significant temperature dependence, we evaluated the effect of temperature on the chemical shift of the fluorine resonances of perfluorotributylamine (FTBA). A linear relationship was found between chemical shift and temperature in vitro. In addition, the relative FTBA chemical shifts were essentially independent of pO2. Chemical shift temperature measurements in vivo, obtained from a 10 microL FTBA bubble in the preretinal vitreous space of the rabbit eye, were in good agreement (+/- 0.5 degrees C) with thermocouple measurements from the same location. Good agreement between the NMR determined temperature and core body temperature was also found. The implication of such temperature measurements for the ultimate accuracy of the pO2 determination based on PFC T1 measurements is discussed. To the best of our knowledge, this report describes the first absolute temperature measurement in vivo by NMR.

Animals↗
PubMedDate not supplied

Preretinal neovascularization in diabetic retinopathy: a preliminary investigation using contrast-enhanced magnetic resonance imaging.

Preretinal neovascularization is a well-described feature of advanced diabetic retinopathy. In this study, contrast-enhanced magnetic resonance imaging was used to examine blood-retinal barrier breakdown associated with preretinal neovascularization in three subjects with proliferative diabetic retinopathy. Using a standard imaging protocol, a varying degree of vitreous enhancement was observed in these eyes. The location and severity of enhancement, judged by visual inspection of the images, corresponded to the fluorescein angiographic and/or clinical appearance of preretinal neovascularization. This result suggests that contrast-enhanced magnetic resonance imaging may prove a reasonable approach to the identification of preretinal neovascularization in eyes with significant media opacities.

Adult↗