PubMed Health⌕ Search

Biomedical subjects

S S Sobin

Publications and source records attributed to S S Sobin.

At least 19 recordsLinked to original sources
PubMed1992

Age related alterations in the response of the pial arterioles to adenosine in the rat.

To evaluate the effects of aging on vasoreactivity of pial arterioles to adenosine and barium chloride, an hydraulically intact cranial window preparation was developed in the rat. The microvasculature of anesthetized 3- and 24-month-old Fischer-344 rats was studied during superfusion with artificial cerebrospinal fluid with and without test agents and results determined by videomicroscopy techniques. In both cohorts, the response of pial arterioles to adenosine was both dose and vessel size dependent: arteriolar dilation increased with increasing concentrations of adenosine and at any given concentration the percent increase in diameter was greater in the smaller vessels. During adenosine superfusion the absolute changes and percent increase in vessel caliber were greater in the young rats. Arteriolar vasoconstriction due to barium chloride was vessel size dependent but there were no significant differences in response between young and aged rats. The results indicated an attenuated cerebrovascular response in aged rats to adenosine, but not to barium chloride. This may be due to a difference in the mode of action in these two compounds. Venules did not respond to adenosine at any concentration.

Adenosine↗
PubMed1992

Histochemical characterization of the aging microvasculature in the human and other mammalian and non-mammalian vertebrates by the periodic acid-Schiff reaction.

Prior histochemical studies with the periodic acid-Schiff (PAS) reaction have shown altered biochemical composition in a limited part of the microvasculature (MV) in aging in two species of laboratory animals. We therefore studied, with the PAS reaction, all the components of the MV in multiple tissues from various immature, adult and aged mammals, including human, and immature and aged nonmammalian vertebrates. We now demonstrate that there is an altered biochemical composition of capillaries, arterioles and venules in various tissues with aging. These are first detectable somewhat beyond half the life-span in man (greater than 45 years), marmoset (5 years) and dog (8 years) and seen in old fish, reptiles and birds. The capillary wall is increasingly PAS+; in arterioles there are focal PAS+ areas in the media which increase in size and number with age and become hyalinized masses. The non-muscular venules are increasingly PAS+ apparently due to a polysaccharide staining of connective tissue elements. These histochemical changes in the MV with aging are in the extracellular matrix and appear to be a specific manifestation of aging in vertebrates. The consequences of such changes in MV aging may be important physiologically.

Adolescent↗
PubMed1992

Acute wound repair in an aged animal: a model for accelerated aging of the microvasculature?

This study of wound repair in the aged rat is based on increased carbohydrate content of various proteins which occurs with aging and is readily seen in the microvasculature (MV). We have used the periodic acid-Schiff (PAS) reaction to identify histochemically the carbohydrate moiety of the glycoproteins found in these blood vessels. In the young rat, as in other young vertebrates, elements of the MV are PAS negative and become increasingly PAS+ beyond the half life span. During acute wound repair in an old animal, the new capillaries and venules are PAS- 2 weeks after injury, moderately PAS+ at 4 weeks, and intensely PAS+ at 8 weeks. Arterioles are present and PAS+ at 6 weeks, and intensively positive at 8 weeks, comparable to vessels remote from the wound site. The MV in wound repair in a young animal remains PAS- throughout healing. Rapid aging of the microvasculature in wound repair in an old animal reproduces histochemically the aging which occurs progressively during the prior 24 months. These histochemical changes may result from successive enzymatic and nonenzymatic glycosylation of the various basement membrane proteins in the microvasculature in both normal aging and wound repair in the aged animal. The latter may serve as a model for study of accelerated aging.

Aging↗
PubMed1991

Demonstration of uniform capillary basal lamina thickness by computer technology.

Blood capillaries are assumed to be circular cylinders composed of an inner layer of endothelial cells surrounded by an acellular uniformly thick basal lamina. The capillary basal lamina is the structural and functional interface between the capillary endothelial cells and the adjacent extracellular matrix, important in growth and control mechanisms of the endothelial cell. Capillaries examined in electron micrographs are cut randomly and a projected image of a capillary other than perpendicular to its long axis will produce artifactual thickening of the assumed uniformly thick basal lamina. We have developed an interactive computer program to determine the thickness of the capillary basal lamina that corrects the thickness resulting from the sectioning artifact. We have applied this methodology to demonstrate that the basal lamina of the pancreatic capillaries of the rat are uniformly thick.

Animals↗
PubMed1988

Elasticity of arterioles and venules in postmortem human lungs.

The elasticity and branching order of noncapillary microscopic blood vessels less than 100 microns diam were studied in human lungs obtained 7-30 h postmortem, using a silicone elastomer method that selectively filled pulmonary arterioles or venules. The lungs were inflated to 10 cmH2O pressure and a gradient of transmural vascular pressure of 0-17 cm H2O, from lobe base to apex, was established in the silicone-filled vascular system. Histological materials were obtained after airway fixation by formaldehyde solution and analyzed for vessel diameter in the branching order of 1, 2, and 3, with the smallest noncapillary vessel designated as order 1, in accord with the Strahler system. The change in vessel diameter within a branching order at different levels of transmural pressure is a derived measure of vascular elasticity expressed as compliance coefficient alpha, alpha Values are 0.128, 0.164, and 0.210 micron/cmH2O or 0.682, 0.472, and 0.354%/cmH2O, respectively, of orders 1-3 for arterioles and 0.187, 0.215, and 0.250 micron/cmH2O or 0.992, 0.612, and 0.424%/cmH2O, respectively, of orders 1-3 for venules. The percent is normalized with D0, which is the value of diameter (D) when the transmural pressure is zero. These data are compared with those for the cat where alpha = 0.274 for similar juxta-alveolar vessels.

Adult↗
PubMed1988

Collagen and elastin fibers in human pulmonary alveolar walls.

The morphology and morphometric data of collagen and elastin fibers in the pulmonary alveolar walls are presented. Specimens were obtained from postmortem lungs quick-frozen at specified transpulmonary pressures. Collagen was stained by silver, and elastin was stained by orcein. Photomicrographs were composed by computer. Young lungs typically show small collagen fibers that radiate from the "posts," whereas larger fiber bundles traverse the septum irrespective of capillary blood vessels. In older lungs, rings of collagen around the posts appear enlarged. Elastin bundles do not show obvious variation in pattern with age and inflation pressure. Statistical frequency distributions of the fiber width and curvature are both skewed, but the square root of the width and the cube root of the curvature have approximate normal distributions. Typically, for young lungs at transpulmonary pressure of 4 cmH2O, the mean of (width)1/2 (in micron1/2) for collagen fibers is 0.952 +/- 0.242 (SD), that of (curvature)1/3 (in micron-1/3) is 0.349 +/- 0.094. The corresponding values for elastin are 0.986 +/- 0.255 and 0.395 +/- 0.094.

Adolescent↗
PubMed1987

Collagen and elastin fibers in human pulmonary alveolar mouths and ducts.

To provide a quantitative basis for the understanding of the mechanical properties of the lung tissue, the morphology of the pulmonary alveolar ducts was studied and the dimensions of the collagen and elastin fiber bundles in the alveolar mouths were measured. Statistical data are presented in this report. It was found that the probability frequency functions of the widths of both the collagen and elastin fibers are skewed to the right, but the fourth roots of the widths are normally distributed. Hence, knowing the mean and standard deviation of (width)1/4, the probability of finding fiber bundles of width D is known. On the other hand, we already know the analytic expressions of the strain energy per unit length of fibers of given width. With the probability distribution of width and an estimation of the length of alveolar mouths, the strain energy of the alveolar mouths can be computed. Then the contribution of the alveolar mouths to the stress in the lung parenchyma due to any strain can be obtained by a differentiation of the strain energy function with respect to that strain.

Autopsy↗
PubMed1985

How many pulmonary alveoli are supplied by a single arteriole and drained by a single venule?

A detailed measurement of histological specimens of the lungs of the cat shows that each terminal precapillary vessel (arteriole) supplies, on the average, 24.5 pulmonary alveoli; each terminal postcapillary vessel (venule) drains, on the average, 17.8 alveoli. These numbers link pulmonary alveolar blood flow in capillary sheets with the flow in pulmonary arteries and veins which are cylindrical tubes. They are key numbers needed for hemodynamic analysis. In the literature, these numbers are variously speculated to be 1 or smaller; thus our results correct, even though only for the cat, an important concept.

Animals↗