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Biomedical subjects

W N Scott

Publications and source records attributed to W N Scott.

At least 73 records · Page 4Linked to original sources
PubMed1985

Age-related changes in carbonic anhydrase of toad lens.

Carbonic anhydrase in the toad lens is immunologically identical to the (high activity) enzyme form present in the erythrocyte. As with the erythrocyte carbonic anhydrase, electrofocusing of the freshly-extracted lens enzyme separated three variants with isoelectric points of 6.1, 5.7 and 5.4, all of which exhibited inhibition properties characteristic of the high activity type of carbonic anhydrase. No evidence of the low activity form of the enzyme was found. In contrast to the erythrocyte isoelectric variants, which are stable in vitro, the three variants of lens carbonic anhydrase exhibited progressive anodization in the course of purification and during storage, and could not be isolated in the original form. Acidification of lens carbonic anhydrase appears to be part of the in vivo aging process of the enzyme protein: the still-active enzyme from the oldest lens region--the nucleus--exhibited a considerably lower isoelectric point than the enzyme extracted from the younger, soft fibers of the lens. Although the specific activity of the carbonic anhydrase from the fibers of lens nucleus was considerably lower than the activity of the enzyme from the younger fibers, the observed modification (acidification) of the aged enzyme did not appear to affect substantially its binding properties towards acetazolamide nor the heat lability of the active protein.

Acetazolamide↗
PubMed1985

An analysis of the content and morphology of human breast microcysts.

The composition of 40 human breast microcysts, dissected from eight biopsy and 14 mastectomy specimens has been analysed. All contained high concentrations of the androgen conjugate, dehydroepiandrosterone sulphate, the median value being more than 1000 times that of plasma. In ten cysts sufficient fluid was available for cationic analysis and in all the potassium concentration exceeded that of sodium. This composition suggests an apocrine derivation of the constituents of breast microcysts. This is substantiated by the finding of PAS diastase positive granules in the epithelium lining all 40 microcysts. These findings indicate that there is a single population of breast microcysts which are lined by epithelium with apocrine secretory activity.

Body Fluids↗
PubMed1985

Intra-articular transfer of the iliotibial tract. Two to seven-year follow-up results.

A proximally based transfer of a composite structure of the iliotibial tract, its osseous insertion, the lateral retinaculum, and part of the vastus lateralis was used in 111 anterior cruciate-deficient knees that were followed for two to seven years. No other ligament procedures were performed simultaneously. The clinical results included a negative Lachman test in 81 per cent (ninety) of the knees, an anterior drawer test of 1+ or less in 84 per cent (ninety-three knees), and a negative pivot-shift sign in 94 per cent (104 knees). Subjectively, 74 per cent (eighty-two) of the knees were rated as excellent; 21 per cent (twenty-three), as good; and 5 per cent (six), as poor. A significant modification in surgical technique, consisting of a limited posterior dissection of the iliotibial band, yielded even better static stability than the original operation did. These results, sustained for as long as seven years, are consistent with the physiological aspects of this transfer. The surgical technique is reproducible and the immediate fixation of bone allows early motion of the knee and reasonable rehabilitation.

Adolescent↗
PubMed1984

pH of human breast cyst fluids.

The pH of 106 human breast cyst fluids has been measured immediately following aspiration. Values ranged from pH 6.3 to 7.8. They correlated with the ratio of Na+ to K+ in cyst fluid and differed significantly in the two populations of fluids which can be defined on electrolyte composition. Storage of cyst fluid for one month at -20 degrees C resulted in an increase in pH by a mean of 0.9 of a unit. pH provides a simple method for typing cyst fluids and this may be of clinical importance as there is evidence that there are differences in the natural history and association with breast cancer in the two populations of breast cysts.

Apocrine Glands↗
PubMed1983

The morphological basis of human breast cyst populations.

Forty human cysts have been examined to determine the relationship between the epithelial lining and the content of sodium (Na+) and potassium (K+) in the cyst fluid. The ratios of Na+ to K+ for cysts lined by flattened epithelium were higher in all cases than the values obtained for cysts lined by apocrine epithelium. These findings suggest a morphological basis for the two populations of human breast cyst fluids which can be defined on cationic content.

Breast Diseases↗
PubMed1983

Classification of human breast cysts according to electrolyte and androgen conjugate composition.

One hundred human breast cyst fluids have been analysed for sodium (Na+), potassium (K+) and dehydroepiandrosterone (DHA) sulphate. Concentrations varied greatly between individual cyst fluids, Na+ from 20 to 185 mmol/l, K+ from 5 to 160 mmol/l and DHA-sulphate from 1.5 to 87 mumol/l. Analysis of the inter-relationships between Na+, K+ and DHA sulphate revealed two major sub-populations of cyst fluids--one group in which Na+ levels were markedly in excess of K+ and DHA sulphate concentrations were low and the other in which K+ was the predominant cation and DHA sulphate concentrations were high.

Androgens↗
PubMed1982

Alterations in mechanical response of aged rat myocardium. Effects of dexamethasone.

1. Mechanical responses of young and old rat myocardium to increasing rates of stimulation were compared. As the animals aged, we found a significant enhancement of the negative force-frequency response and a decline in the velocities of contraction and of relaxation. 2. At 6 months of age, there were no differences between rats obtained from commercial sources and a group of rats obtained from a colony maintained at the National Institute of Aging. 3. At 24 months, the negative force-frequency response was considerably greater in the former group of animals than in the latter. 4. The sensitivity to the calcium concentration in the tissue bathing solution was significantly increased in aged heart preparations. Increasing the calcium concentration reduced the negative inotropy and the decline in the velocities of contraction and relaxation. The enhancement by calcium was directly proportional to the concentration of the metal in the bathing solution. 5. When aged animals were pretreated with pharmacological doses of dexamethasone, the age-induced alterations in the mechanical responses were reversed. The aged, dexamethasone-treated myocardium also became refractory to calcium concentrations above 2.7 mM in the bathing solution. 6. It is suggested that aging induces multifocal defects and that steroid hormones play a role in the maintenance of integrity of the myocardium. The action of the steroids is on the sarcolemma, the contractile proteins and the sarcoplasmic reticulum.

Aging↗
PubMed1982

Mineralocorticoid-induced membrane proteins in MDCK cells.

The Madin-Darby canine kidney (MDCK) cell line, which exhibits properties indicative of a distal tubule origin, evidently binds and responds to mineralocorticoid hormones. We investigated the effects of aldosterone and deoxycorticosterone on protein synthesis in MDCK cells grown either in medium supplemented with serum or in a hormonally defined, serum-free medium. Aldosterone induced the synthesis of at least 2 membrane proteins with molecular weights of 35000 and 14000. The MDCK line may prove a useful model system for examining the mechanism of mineralocorticoid-regulated sodium transport and, in particular, the identification and study of hormone-induced proteins in a homogeneous cell population.

Aldosterone↗
PubMed1982

Principles of surgical technique in knee arthroplasty.

Surgical technique in knee arthroplasty is quite demanding, requiring an understanding of arthritic deformities and meticulous attention to the principles of component insertion. Increasing clinical success in knee arthroplasty can be attributed to better designs, materials, and, most significantly, surgical technique. Although the "new generation" of instruments enhances the likelihood of a reproducible technique, anatomic variation precludes precise application of any instrumentation to all knees. The surgeon must recognize the weakness of the selected system while understanding the principles of conformity, alignment, and rotation to insure technical accuracy.

Arthritis↗
PubMed1981

Insulin-induced proteins in the toad urinary bladder.

Insulin increases active sodium transport by the toad urinary bladder within 15 min, an effect which persists for an least 20 h. In tissues pre-treated with inhibitors of transcription or translation, sodium transport briefly increases after insulin addition but returns to basal levels within 60-90 min. We have studied the effects of insulin on the incorporation of radioactive amino acids into mucosal cell proteins. Insulin had no detectable effect on the uptake of amino acids nor on their incorporation into total protein; however, using a dual label technique, we found that insulin increases the incorporation of amino acids into specific soluble and plasma membrane proteins of the granular mucosal cell. The time course and dose-response relationship of the induction of protein synthesis by insulin suggest that these proteins may play a role in the sustained elevation of sodium transport by insulin.

Amino Acids↗
PubMed1981

Mechanisms of hormonal modulation of ion transport in the toad's urinary bladder. Subcellular localization of aldosterone-induced proteins.

A dual-label isotope technique was used to study the effects of aldosterone upon the incorporation of amino acids into proteins of the in vitro toad urinary bladder. Following labeling, the mucosal cells were disaggregated and the mitochondria-rich and granular cells were separated. Proteins with an elevated isotope ratio were found in a plasma membrane fraction (170 000, 110 000 and 85 000 daltons) and in the cytosol (36 000 and 6 000 daltons) of the preparations enriched in mitochondria-rich cells. These effects of aldosterone were blocked by cycloheximide. There was no evidence that aldosterone had induced the incorporation of labeled amino acids into carbonic anhydrase isolated from the soluble fraction by affinity chromatography. The results suggest that the physiologic response of the toad bladder to aldosterone is related to the synthesis of both soluble and plasma membrane proteins.

Aldosterone↗
PubMed1981

Cell-free translation of RNA isolated from aldosterone-treated toad bladder mucosal cells.

The stimulation of sodium transport by aldosterone in target tissues requires the synthesis of both mRNA and proteins. Aldosterone-induced mRNA and proteins have been demonstrated in toad urinary bladder and rat kidney. We have isolated total RNA and poly(A)-containing RNA from hormone-treated and untreated toad bladder mucosal cells for translation in a rabbit reticulocyte lysate system. Aldosterone-induced proteins synthesized in this system have physical properties similar to those of aldosterone-induced proteins synthesized in the intact toad bladder.

Aldosterone↗
PubMed1981

Role of induced proteins in insulin-stimulated sodium transport.

Insulin increases active sodium transport by the toad urinary bladder, an effect that begins with 15 minutes and persists for at least 20 hours. Although pretreatment of bladders with inhibitors of RNA or protein synthesis has no effect on the response to insulin within the first hour, these agents block the long-term component of insulin-stimulated sodium transport. To examine the relationship of protein synthesis to the sustained increase in sodium transport elicited by insulin, we have studied the effects of the hormone upon the incorporation of radioactive amino acids into mucosal cell proteins. There is no detectable effect of insulin on the uptake of aminoisobutyric acid into mucosal cells or on the incorporation of labeled precursors into total protein; however, using a dual-label technique, we find that insulin increases the incorporation of amino acids into specific soluble and plasma-membrane proteins of granular mucosal cells. Insulin has no discernible effect upon the incorporation of amino acids into proteins of mitochondria-rich mucosal cells. Thus the effects of insulin upon sodium transport appear to be the result of two separate mechanisms, (1) a short-term response that is independent of protein synthesis and (2) a long-term response that is expressed after the first hour of hormone treatment and that requires the synthesis of one or more specific proteins in the granular cell.

Amino Acids↗
PubMed1981

Insulin-induced alterations in the lactoperoxidase-catalyzed radioiodination of membrane proteins of the toad bladder epithelium.

Insulin-stimulated sodium transport in the toad urinary bladder consists of two components, a brief element of rapid onset that is independent of protein synthesis, and a sustained increase, slower in onset, that is dependent upon RNA and protein synthesis. The mucosal epithelium of the toad bladder was labeled by lactoperoxidase-catalyzed radioiodination (125I) following 15 min and 3 h exposure to insulin. The membrane of "mitochondria-rich" and "granular" mucosal cells from these tissues were analyzed by electrophoresis in SDS-urea. Compared to untreated tissues, membranes of "granular" mucosal cells from tissues exposed to insulin for 15 min contained a band (Mr = 15,000) with significantly increased labeling. Bladders exposed to insulin for 3 h showed no consistent increase in labeling. These data suggest that there are differences in the conformation of apical membrane proteins during the two phases of hormone-induced sodium transport. The technique may also offer an opportunity to identify "effector" proteins mediating this and other insulin responses.

Animals↗