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Biomedical subjects

J Hirsch

Publications and source records attributed to J Hirsch.

At least 307 records · Page 17Linked to original sources
PubMed1975

Comparison of soflens contact lenses (polymacon) with hard contact lenses and spectacles.

A study, comparing Soflens TM contact lenses (polymacon) with hard contact lenses and spectacles, and using 150 male and female patients, has been done. Volunteers qualified for the study if they had healthy eyes and had worn one type of corrective lenses for six months before they were interviewed and examined. During each patient's examination, his type of correction was not known. Such matters as visual acuity, corneal measurements and average wearing time were considered. (Soflens contact lenses were felt to be safer than hard contact lenses.)

Adolescent↗
PubMed1975

Colloidal lanthanum as a marker for impaired plasma membrane permeability in ischemic dog myocardium.

Colloidal lanthanum salts have an average particle size of 40 degrees A; consequently, this electron-opaque marker remains extracellular and does not cross the intact plasma membrane. The affinity of lanthanum for calcium-binding sites on mitochondrial membranes makes it possible to demonstrate loss of plasma membrane integrity at the cellular level in ischemic myocardium. Biopsies were obtained from infarcted, marginal and normal areas 3 1/2 hours after ischemia was produced in 9 anesthetized closed-chest dogs by electrically induced thrombosis of the left anterior descending coronary artery. The tissue was immediately fixed in 4% glutaraldehyde and 0.1 M cacodylate buffer containing 1.3% La(NO3)3, pH 7.4, for 2 hours. In normal control tissue prepared this way the lanthanum tracer, as expected, was confirmed to the extracellular spaces, including, basement membranes, gap junctions and portions of the intercalated discs. Specimens taken near the center of frank infarctions all contained intracellular as well as extracellular lanthanum. Intracellular lanthanum could be seen evenly distributed around lipid droplets and in focal deposits around mitochondria. Only when mitochondria were disrupted did lanthanum gain access to internal sites on mitochondrial membranes. Areas marginal to the infarct contained cells in varying stages of degeneration including many that appeared normal by morphologic criteria alone. Intracellular lanthanum was present in many but not all of the marginal cells in which degenerative changes could be seen. Similarly a few of the cells that appeared morphologically normal contained intracellular lanthanum. The entry of lanthanum into some of these marginal cells and its exclusion from adjacent cells demonstrated that ischemic injury affects the permeability properties of the plasma membrane and independently of other intracellular morphologic changes and that lanthanum can be a sensitive indicator of such alteration in membrane permeability.

Animals↗
PubMed1975

Cytochemical localization of lysosomal enzyme activity in normal and ischemic dog myocardium.

The effect of ischemia on the integrity of myocardial lysosomes was observed 3 1/2 and 24 hours after the production of infarcts in 20 anesthetized closed-chest dogs by electrically induced thrombosis of the left anterior descending coronary artery. Biopsies from normal, marginal and infarcted areas were fixed and incubated to localize the lysosomal enzymes acid phosphatase and aryl sulphatase. Reaction product in normal cells was localized in small circular or oblong profiles between bundles of myofilaments and adjacent to mitochondria. In addition, curvilinear, membrane-bound profiles containing reaction product were found in close apposition to transverse tubules and near the free margins of the myocardial cells. Thus the distribution of elements of the sarcoplasmic reticulum. Additional reaction product was also seen in residual bodies, on myelin figures, and in the few conventional appearing spherical lysosomes. Little or no acid phosphatase or aryl sulphatase reaction product was seen in the sarcoplasmic reticulum of infarcted myocardium. The degree of cellular degeneration correlated with disappearance of enzyme activity from the sarcoplasmic reticulum and included disruption of membranes and loss of mitochondrial matrix and erosion of I but not A bands. Marginal areas showed variable amounts of cellular degeneration. Separation of myofilament bundles and loss of glycogen correlated with the localized disappearance of acid phosphatase and aryl sulphatase activity in marginal tissue. Disruption of mitochondrial and erosion of I bands correlated with extensive loss of these enzymes. The data suggest that degeneration of myocardial cells following ischemic injury is associated with release of endogenous lysosomal enzymes from the sarcoplasmic reticulum.

Acid Phosphatase↗
PubMed1974

Postnatal development of adipocyte cellularity in the normal rat.

It has been shown by several investigators that adipocyte number is stable in mature human beings and several species of rodents. Although the number of new cells appearing in the adipose depot can be measured histometrically and by Coulter counting of osmium-fixed cells, such methods do not distinguish between "lipid filling" of preexistent adipocytes and synthesis of new adipocytes. The experiments reported here using in vivo injection of [(3)H]thymidine show that synthesis of new adipocytes in the Sprague-Dawley rat continues after birth and ceases before sexual maturity. Furthermore, during the second and third postnatal weeks, a "bed" of preadipocytes is synthesized. Preadipocytes may take as long as 30 days to appear as mature adipocytes.

Adipose Tissue↗
PubMed1973

Histamine: effect on self-stimulation.

When injected discretely into the lateral hypothalamus of rats, histamine inhibited electrical self-stimulation at the injection site without affecting self-stimulation in the contralateral lateral hypothalamus. This effect was blocked by prior treatment with antihistaminics. Histidine, the amino acid precursor of histamine, produced a similar effect after a delay of 6 to 10 minutes.

Animals↗