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J M Strum

Publications and source records attributed to J M Strum.

54 records · Page 3Linked to original sources
PubMed1976

Differential covalent labeling of apical and basal-lateral membranes of the epithelium of the toad bladder.

The apical (luminal) plasma membrane of toad bladder epithelial cells has been labeled with (125I) diazo-diiodo sulfanilic acid (125I-DDISA) as demonstrated by electron-microscopic autoradiography. The silver grains (125I) were localized exclusively to the apical surface. At concentrations of DDISA of 10(-3) M or less, binding to the apical membrane had no significant effect on the fine structure of the epithelium. At concentrations of DDISA of 10(-6) M or less, the baseline short-circuit current (SCC), and the response to cyclic 3',5'-adenosine monophosphate (cAMP) plus theophylline were unimpaired. At 10(-5) M, baseline SCC was unchanged and the response to cyclic AMP plus theophylline was enhanced. At concentrations of 10(-4) M and greater baseline SCC was depressed and the response to the nucleotide inhibited. The basal-lateral epithelial plasma membranes were labeled by exposing the serosal side to pyridoxal phosphate and reducing the resultant Schiff base with sodium borotritide (3H-NaBH1). In electron-microscopic autoradiographs, the silver grains (3H) were found over the basal and lateral surfaces of the epithelium. At concentrations of pyridoxal phosphate of 10(-4) M and 3H-NaBH1 of 10(-3) M, there were no significant changes in the fine structure of the epithelium. Addition of pyridoxal phosphate (10(-4) M) and NaBH4 (10(-3) M) to the serosal side decreased the baseline SCC significantly but not the response to vasopressin. Covalent attachment of the 125I and the 3H was indicated by resistance to elution in the preparation of the sections for electron-microscopy and the reagent requirements for binding.

Animals↗
PubMed1976

Comparative ultrastructural analysis of two tortoise bladders, Testudo graeca and Geochelone carbonaria.

Urinary bladders from the desert tortoises, Testudo graeca and Geochelone carbonaria were removed at specific times during the year and species in all bladders examined: (1) granular cells, (2) mitochondria-rich cells, and (3) basal cells. Cells analogous to these three types have also been observed in amphibian bladders (from toad Bufo marinus and bullfrog, Rana catesbiana) and reptilian bladders (from Pseudemys scripta and Clemmys caspica). Both tortoises have an incomplete layer of basal cells so that the granular and mitochondria-rich cells extend from the lumen to the basement membrane: something was not observed in bladders from bullfrog or turtles. A flask-shaped light cell was observed in the Geochelone carbonaria bladder obtained in April. No counterpart of this cell was seen in the same species sacrificed in January, or in any of the Testudo graeca bladders, although a similar cell has been described in the turtle, Pseudemys scripta (Rosen, Expt. Molec. Path., 12: 286-296, '70). This study was undertaken to characterize the cell types present in tortoise bladder and to compare them with cell types in the bladder of the turtle, bullfrog and toad.

Animals↗
PubMed1975

Autoradiographic localization of corticosterone receptors (type III) to the collecting tubule of the rat kidney.

Recently, a class of receptors exhibiting high affinity for corticosterone was described in rat kidney (Feldman, D. et al., Endocrinology 92: 1429, 1973). These receptor sites exhibited negligible affinity for dexamethasone and aldosterone and were designated Type III to distinguish them from sites having high affinity for aldosterone (Type I), and sites with high affinity for dexamethasone and corticosterone (Type II). To visually localize Type III sites in the kidney and demonstrate whether or not they represent intracellular steroid receptors, we used an autoradiographic procedure for diffusible substances. Male adrenalectomized rats were injected intravenously with the following combination of steroids per 100 g body weight: 4 x 10(-9) mol [3H]corticosterone, 4 x 10(-9) mol unlabeled aldosterone, and 4 x 10(-9) mol unlabeled dexamethasone. To differentiate "nonspecific" binding, each experimental animal was paired with a control animal that received the same steroids plus 250-fold unlabeled corticosterone. At 3 min, 10 min, and 30 min, kidneys were removed, cut into quadrants, and frozen in isopentane cooled by liquid nitrogen. For autoradiography, 4 mum frozen sections were cut, pressed into contact with emulsion precoated slides at -30 C, melted and simultaneously dried under a jet of dry nitrogen gas, and exposed at 4 C for 2 to 6 weeks. At all three time intervals, silver grains representing [3H]corticosterone binding sites, were concentrated over collecting tubules, only in the outer medulla and cortex (those in the inner medulla and papilla were not labeled). In the labeled segments of the nephron, some of the cells showed an apparent high ratio of cytoplasmic to nuclear grains and in others nuclear labeling was more prominent. A small population of cells within labeled collecting tubules (possibly dark cells) were not labeled. Although no function can yet be ascribed to Type III receptors in the kidney, they may represent an important steroid-mediated renal mechanism.

Animals↗
PubMed1972

Radioautographic demonstration of 5-hydroxytryptamine- 3 H uptake by pulmonary endothelial cells.

The lung is able to rapidly remove 5-hydroxytryptamme (5-HT) from the circulation by a Na(+)-dependent transport mechanism. In order to identify the sites of uptake, radioautographic studies were done on rat lungs which had been isolated and perfused with 5-HT-(3)H and 0 5 mM iproniazid, a monoamine oxidase inhibitor. In control experiments 10(-4)M imipramine was added to the perfusate to inhibit the membrane transport of 5-HT At the light microscope level, silver grains were seen concentrated near capillaries and in the endothelium of large vessels From electron microscope radioautographs a semiquantitative grain count was made and 90% of the silver grains were observed over capillary endothelial cells. The grains were found over the nucleus and cytoplasm of the cell and shewed no preferential association with any particular cytoplasmic inclusion bodies, organelles, or vesicles Other cell types were unlabeled except for a few mast cells, certain vascular smooth muscle cells, and one nerve ending. This radioautographic demonstration of the cell type responsible for the rapid removal of 5-HT from the lung circulation clearly establishes the existence of a new metabolic role for pulmonary endothelial cells.

Animals↗
PubMed1971

Appearance and function of endogenous peroxidase in fetal rat thyroid.

Iodination within the thyroid follicle is intimately associated with a thyroid peroxidase. In order to locate the in vivo site of iodination, the initial cytochemical appearance of this enzyme has been determined in fetal rat thyroid and its presence correlated with the onset of iodinated thyroglobulin synthesis. Peroxidase first appears in follicular cells during the 18th day of gestation. It is seen first in the perinuclear cisternae, the cisternae of the endoplasmic reticulum, and within the inner few Golgi lamellae. These organelles presumably represent sites of peroxidase synthesis. During the 19th and 20th days of gestation, there is a tremendous increase in peroxidase activity. In addition to the stained sites described, there are now many peroxidase-positive apical vesicles in the follicular cells. Newly forming follicles stain most conspicuously for peroxidase, the reaction product being heavily concentrated at the external surfaces of apical microvilli and in the adjacent colloid. Iodinated thyroglobulin becomes biochemically detectable in thyroids during the 19th day of gestation and increases greatly during the 20th day. The parallel rise in peroxidase staining that just precedes, and overlaps, the rise in iodinated thyroglobulin, suggests that apical vesicles and the apical cell membrane are the major sites of iodination within the thyroid follicle.

Animals↗
PubMed1970

Cytochemical localization of endogenous peroxidase in thyroid follicular cells.

Endogenous peroxidase activity in rat thyroid follicular cells is demonstrated cytochemically. Following perfusion fixation of the thyroid gland, small blocks of tissue are incubated in a medium containing substrate for peroxidase, before being postfixed in osmium tetroxide, and processed for electron microscopy. Peroxidase activity is found in thyroid follicular cells in the following sites: (a) the perinuclear cisternae, (b) the cisternae of the endoplasmic reticulum, (c) the inner few lamellae of the Golgi complex, (d) within vesicles, particularly those found apically, and (e) associated with the external surfaces of the microvilli that project apically from the cell into the colloid. In keeping with the radioautographic evidence of others and the postulated role of thyroid peroxidase in iodination, it is suggested that the microvillous apical cell border is the major site where iodination occurs. However, that apical vesicles also play a role in iodination cannot be excluded. The in vitro effect of cyanide, aminotriazole, and thiourea is also discussed.

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