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Biomedical subjects

W N Scott

Publications and source records attributed to W N Scott.

At least 109 records · Page 6Linked to original sources
PubMed1975

Identification of aldosterone-induced proteins in the toad's urinary bladder.

Aldosterone (the 8,11-hemiacetal 0f 11beta,21-dihydroxy-3,20-dioxo-4-pregnen-18-al) markedly stimulates sodium transport in a number of epithelial tissues. We have attempted to determine whether aldosterone induces the synthesis of specific protein(s) in the course of its action upon the toad urinary bladder. Paired hemibladders were incubated in media containing either [3H]methionine or [35S]methionine; aldosterone in physiologic concentrations was added to one bath and, after incubation, the intact "mitochondria-rich" (MR) and "granular" (G) mucosal cells were isolated. The ratio (3H/35S) was used to identify proteins whose synthesis was induced in the mucosal cells of the steroid-treated bladders. Using exclusion gel chromatography and isoelectric focusing, we identified several aldosterone-induced proteins in the supernatant (105,000 x g) fraction of the MR cell. None was evident in this fraction of the G cell. These proteins have apparent molecular weights ranging from 17,000 to 38,000 and the isoelectric point of the major component is 4.5. Corticosterone (11beta,21-dihydroxy-4-pregnene-3,20-dione) induced the synthesis of proteins in the G cells, but none of these proteins was similar in molecular weight to the aldosterone-induced proteins in the MR cell. Our findings support the hypothesis that aldosterone induces the synthesis of specific proteins and indicate that, in this tissue, these proteins are synthesized by the MR cell.

Aldosterone↗
PubMed1975

Ten years' experience with femoral shaft fractures.

One hundred one patients with femoral shaft fractures treated by open reduction and intramedullary fixation have been presented. The results demonstrated no nonunions in nonpathologic bone; less than 2% infection; clinical union in 4 to 6 months; radiologic union at 6 to 8 months; excellent range of knee motion in more than 90% of patients; unsupported full weight-bearing usually present by the eighth postoperative week, and an average hospital stay of 6 to 7 weeks. The advantages and disadvantages of the most common methods of treatment of femoral shaft fractures have been reviewed. The non-operative approach of cast-bracing has yielded encouraging results in the hands of those well-trained in its application. Weighing the advantages and disadvantages of the operative and nonoperative techniques, as described, we feel that open reduction and internal fixation with an intramedullary rod is still the treatment of choice for most femoral shaft fractures, in the hands of most orthopaedic surgeons.

Adolescent↗
PubMed1975

[Hematological studies on cows pasturing on Brachiaria radicans napper in winter time (author's transl)].

A group of six adult cows Holstein-Frision was left grazing on a pasture formed exclusively with Brachiaria radicans Napper. This investigation was was undertaken during the rather dry winter with the graminea showing a low nitrat content. The animals failed to present any of the typical simptoms of intoxication and the weekly clinical and hematologycal examinations detected a hyperchromic macrocytic anaemia eventually jointed to anisocytosis and basophylic stippling in the red cells. The anaemia was controlled by removing the animals from the pasture.

Anemia, Hypochromic↗
PubMed1975

Ascorbic acid stimulates chloride transport in the amphibian cornea.

The cornea of the toad, Bufo marinus, actively transports chloride from the endothelial to the epithelial surface. This transport process has been related to the maintenance of the normal transparency of the cornea. Ion transport, as evidenced by the short-circuit current (SCC), is markedly stimulated by physiologic concentrations of ascorbic acid. Measurement of the unidirectional fluxes of 36Cl and 22Na shows that the increase in SCC is due primarily to a stimulation of the active transport of chloride.

Animals↗
PubMed1974

Partition of tissue functions in epithelia: localization of enzymes in "mitochondria-rich" cells of toad urinary bladder.

The mucosal epithelium of the toad urinary bladder reabsorbs sodium, acidifies the urine, and is responsive to neurohypophyseal hormnones. Mucosal epithelial cells, consisting of two major morphologic cell types, "mitochondria-rich" and "granular," were removed from the bladder and separated by density gradient centrifugation. The mitochondria-rich cells contained three times as much carbonic anhydrase activity as the granular cells. Oxytocin caused a 235 percent increase in the adenosine 3',5'-monophosphate content of mitochondria-rich cells but had no effect on the granular cells. The evidence indicates that the mitochondria-rich cell, which accounts for only 15 percent of the mucosal cells, plays a major role in the mediation of sodium ion and hydrogen ion transport in the toad bladder and is a specific site of action of neurohypophyseal hormones.

Animals↗
PubMed1973

Cyclic AMP and sodium transport. Quantitative and temporal relationships in toad urinary bladder.

The effects of oxytocin upon tissue cAMP content and short-circuit current (SCC) were measured in the urinary bladder of the toad, Bufo marinus. Tissue cAMP levels doubled before any increment in SCC was observed, the two hormone responses were quantitatively related, and a threshold level for an effect of cAMP upon sodium transport was demonstrated. The period of time over which cAMP levels continued to rise after the threshold level had been attained seemed invariant with hormone concentration. The rate at which cAMP levels rose increased with hormone concentration yielding hormone concentration-dependent maximal levels. The decay of cAMP levels was delayed when sodium influx was curtailed, suggesting a sodium-regulatory effect upon tissue cAMP levels.

Animals↗
PubMed1968

Osmotic volume flow in the proximal tubule of Necturus kidney.

Volume changes due to osmotic flow in the distal portion of proximal tubules of Necturi were measured by the split oil drop technique. In agreement with previous findings no volume flow was induced by NaCl concentrations close to 60 mM. The tubule wall was found to be permeable to plasma electrolytes, which have an apparent reflection coefficient of 0.69. The mean apparent hydraulic conductivity was 0.33 x 10(-11) cm(3)/dyne sec, comparable with other epithelia. A number of lipid-insoluble nonelectrolytes of widely varying molecular size had apparent reflection coefficients of about 0.5. In view of the insensitivity to molecular size it seems likely that apparent reflection coefficients determined from tubular volume changes depend primarily on the porosity of the intercellular barrier closest to the lumen and give little information about the subsequent fate of the test substances.

Animals↗