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U S Ryan

Publications and source records attributed to U S Ryan.

152 records · Page 9Linked to original sources
PubMed1976

Localization of angiotensin converting enzyme (kininase II). II. Immunocytochemistry and immunofluorescence.

The cellular and subcellular sites of angiotensin converting enzyme (kininase II) in lung tissue and endothelial cells in culture were examined by immunocytochemical and immunofluorescence techniques. Converting enzyme is capable of inactivating bradykinin and of converting angiotensin I to its potent lower homolog, angiotensin II. Immunocytochemistry at the electron microscope level used goat anti- (pig lung and angiotensin converting enzyme) coupled to 11-MP (11-microperoxidase) via glutaraldehyde or to 8-MP (8-microperoxidase) via a bifunctional active ester, bis-succinyl succinate. The latter conjugate, which does not contain complex polymers, has been characterized in detail in terms of immunoreactivity and peroxidase activity.

Animals↗
PubMed1975

Alveolar type II cells: studies on the mode of release of lamellar bodies.

There is increasing evidence that type II alveolar cells are capable of synthesizing surface active material like that obtained from the airways. However a number of problems remain to be solved before it can be stated conclusively that type II cells synthesize the surface active material of the terminal airspace. Among these problems is that of secretion. A number of previous studies have given evidence of the release of lamellar bodies by merocrine secretion. In this study morphologic evidence is presented which supports the view that secretion of lamellar bodies is accomplished by exocytosis. At the apical surface of type II cells, sites can be found where the limiting membrane of the lamellar body is clearly fused with the type II cell plasma membrane and an open channel exists between the contents of the lamellar body and the alveolar space. At these sites the lamellar contents extrude into the airspace with consequent loss of the highly compact organization of intracellular lamellar bodies. The intactness and continuity of the membranes can be traced for the full extent of the exocytosis site. Freeze-etch replicas of the membranes of type II cells show depressions which may represent the sites of discharged lamellae. In addition, tongue-like folds are seen which could be explained as the extensions of cytoplasm which surround the releasing lamellar body and which may flap over the exocytosis pit after discharge. Micrographs of the alveolar space show disorganized lamellar whorls which appear to be unravelling to produce tubular myelin. In view of the unusually large size and lipid composition of lamellar bodies, a mechanism involving hydration of mucopolysaccharide contents as an aid to expulsion of lamellar contents is suggested.

Animals↗
PubMed1975

Fenestrated endothelium of the adrenal gland: freeze-fracture studies.

Little is known of how adrenal hormones pass from the interstitial to the vascular space. We have begun to examine the adrenal endothelium as a barrier to hormone passage, by the freeze-fracturing technique. The endothelium of both cortex and medulla is fenestrated. Fractures from both regions show endothelial cells to be extremely thin in regions where fenestrations are abundant. En face fractures show fenestrae disposed in tracts; the fenestrae reaching a distribution of 35/mu2. In both cortex and medulla there are areas of continuous endothelium which contain caveolae. Structures believed to represent fenestra diaphragms contain randomly disposed particles and occasional pits. We have not identified in replicas the central ring and pore described in thin-sectioned material (Elfvin, 1965). The main differences between freeze-fractured aspects of cortical and medullary endothelium are the greater abundance of caveolae in the medulla and the size of the fenestrae (fenestra rims in the medulla are 525-780 A in diameter; in the cortex 570-1660 A). These differences may reflect the different embryological origins of the medulla and cortex. While caveolae may participate in hormone transport, there is no evidence for this. In the medulla the caveolae are more numerous and may have a function not necessarily related to transport. Possibly, caveolae play a role in processing hormones and related substances. For example, ATP and specific proteins are released as well as epinephrine during exocytosis from chromaffin cells. Epinephrine enters the vascular space but ATP does not. ATPase enzymes are a common feature of caveolae of other endothelia and may occur as well in adrenal endothelium.

Adrenal Cortex↗
PubMed1975

Subcellular localization of pulmonary antiotensin-converting enzyme (kininase II).

Goat antibodies to pig lung angiotensin-converting enzyme (kininase II) were conjugated to microperoxidase. Rat lung tissue, previously incubated with non-immune goat serum, was incubated with the antibody-microperoxidase conjugate and then with H2O2 and 3,3-diaminobenzidine. Electron microscopy revealed reaction product on the plasma membrane and caveolae of endothelial cells, especially those of capillaries and venules. These results support the hypothesis that angiotensin I and bradykinin are metabolized by enzymes on the luminal surface of pulmonary endothelial cells.

Angiotensin II↗
PubMed1975

A sensitive radiochemical assay for angiotensin-converting enzyme (kinase II).

[[125I]Tyr8]Bradykinin is degraded by angiotensin-converting enzyme to [125I]Tyr-Arg. The reaction product can be separated completely and recovered nearly quantitatively from unchanged substrate by cation-exchange chromatography. Thus it is possible to use [[125I]Tyr8]bradykinin at high specific radioactivity (about 400Ci/mmol) to measure the small quantities of angiotensin-converting enzyme encountered in small-scale cultures of pulmonary endothelial cells.

Animals↗
PubMedDate not supplied

Enzymatic lysis of sulfated glycosaminoglycans reduces the electrophoretic mobility of vascular endothelial cells.

The main purpose of this work was to identify the macromolecules carrying the surface charge of endothelial cells. This was done by measuring changes in cell electrophoretic mobility caused by enzymatic removal of glycocalyx components. Endothelial cells were removed from the bovine pulmonary artery using nonenzymatic procedures, plated, and identified by immunocytochemical methods and electron microscopy. Cultured cells were suspended in saline and placed in the lumen of a capillary in a Rank Brothers electrophoresis instrument. Voltage was applied between the ends of the capillary, and the velocity acquired by the cells was measured with a microscope. Preincubating the cells in protein-free saline for 1 h reduced the mobility by 25%. This reflects the loss of proteoheparan sulfate from the cell surface. Cell mobility was totally suppressed by exposing the entire cell surface to chondroitin sulfate lyase, but it was only slightly diminished when the enzyme was applied only to the cell side facing the culture medium. A partial decrease in mobility was obtained after enzymatic removal of either heparin, heparan sulfate, or collagen. The results indicate that sulfated glycosaminoglycans are the main carriers of the surface change in vascular endothelial cells. The asymmetrical effect of chondroitinase on the two sides of the cell indicates a distribution polarization for glycosaminoglycans in endothelial cells.

Animals↗