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Biomedical subjects

W W Wright

Publications and source records attributed to W W Wright.

At least 55 records · Page 3Linked to original sources
PubMed1983

Identification of stage-specific proteins synthesized by rat seminiferous tubules.

Experiments were conducted to determine how the cycle of the seminiferous epithelium influenced synthesis and secretion of proteins by seminiferous tubules. Tubular segments were treated with collagenase and then cultured with [35S]methionine. These myoid cell-depleted tubules isolated from different stages of the epithelial cycle exhibited, at Stages VI and XII, two distinct peaks of secretion of total radiolabeled proteins. Two-dimensional gel electrophoresis indicated that the patterns of secreted proteins from these two stages were remarkably different, while those from other stages were intermediate between those at the peaks. At least 15 proteins were secreted cyclically, many of them previously unrecognized products of the seminiferous epithelium. One product, designated Cyclic Protein-2 (CP-2), exhibited a pronounced cycle of secretion, its peak at Stage VI being 30-fold greater than at its nadir at Stages XII-XIV. Further investigation indicated that CP-2 did not appear to originate from myoid cells or dispersed germ cells but could be recovered from Sertoli cell-enriched cultures prepared from Stage VI tubules. Protein secretion by tubular segments was also characterized by immunoprecipitation with two polyspecific antisera directed against Sertoli cell products. Five secretory proteins were identified which had cycles different from one another and from CP-2. In contrast to secreted products, the synthesis of most cellular proteins by tubular segments remained relatively constant throughout the cycle. It is concluded: 1) segments of the seminiferous epithelium secrete proteins into the culture medium which are distinct from cellular proteins; 2) the synthesis of many of these proteins varies with the epithelial cycle; and 3) several of the secreted proteins are of Sertoli cell origin, including a newly identified protein, CP-2. This indicates that the morphology and the protein synthetic capacity of the seminiferous epithelium are coordinated over space and time.

Animals↗
PubMed1983

Spermatogenesis in vitro: completion of meiosis and early spermiogenesis.

In vitro formation of haploid spermatids has not been convincingly demonstrated in mammals. To investigate this problem we selected defined segments of rat seminiferous tubules containing late pachytene and diakinetic primary spermatocytes (Stages XII and XIII of the cycle) for culture in a chemically defined medium. After 2 days, most spermatocytes completed both meiotic divisions, and by 6 days the tubular epithelium developed morphologic characteristics of Stage V in which the newly formed spermatids had acrosomic systems characteristic of step 5 spermiogenesis. The seminiferous tubules also differentiated biochemically as evidenced by increased production of proteins characteristically secreted by Stage V. Since this in vitro differentiation of the germinal epithelium occurred in the absence of testosterone and FSH, we conclude that late pachytene spermatocytes and their associated Sertoli cells have all the information required for both meiotic divisions and early spermiogenesis.

Animals↗
PubMed1982

The hemicastrated rat: definition of a model for the study of the regulation of testicular steroidogenesis.

A comprehensive study has been made of the hemicastrated rat from 2 to 12 months of age in order to define what might represent an ideal model in which to study testicular regulation. Although there was no compensatory hypertrophy in the remaining testis of the mature hemicastrated rat, levels of plasma testosterone fell significantly within 4 h after surgery in all age groups older than 3 months, and were restored to normal levels almost immediately, usually within 8 h. There were no significant changes in LH and prolactin, and the significant rise in FSH was sufficiently delayed (2 days or more) to suggest that none of these three hormones was implicated in any obvious way in the compensatory restoration of plasma testosterone levels. Although a single testis was capable of maintaining normal plasma testosterone concentrations, its response to human chorionic gonadotrophin at 24 h after hemicastration was significantly less than that of intact animals, suggesting that the single testis was functioning at near-maximal capacity. The hormonal responses to repetitive blood sampling and to sham-surgery simulated the response to hemicastration remarkably. However, these responses were never statistically significant in within-group analysis, and therefore did not obscure the significant fall of plasma testosterone levels in response to hemicastration. The basic mechanism by which plasma testosterone is restored in the hemicastrated rat is still unknown, but the options have been narrowed.

Animals↗
PubMed1981

Sertoli cells secrete both testis-specific and serum proteins.

The secretions of the Sertoli cell were examined with two polyvalent antisera--one prepared against proteins in rat serum and the other against testis-specific proteins in rete testis fluid. These antisera detected 12 serum and 9 testis-specific proteins in rete testis fluid. To determine the origin of these proteins, primary cultures enriched in Sertoli cells were incubated with [35S]methionine, and the radiolabeled proteins in the medium were immunoprecipitated. Gel electrophoresis of the two immunoprecipitates resolved eight serum and nine testis-specific proteins. These two sets of proteins were specifically bound to their respective antiserum and were immunologically distinct. Medium from Sertoli cell cultures contained 10 times more of the testis-specific proteins than did cultures enriched for testicular myoid or interstitial cells. The concentration of the serum proteins in Sertoli cell medium was 5 and 10 times greater, respectively, than in myoid or interstitial cell preparations. The proteins from Sertoli cells were next characterized on two-dimensional gels. Seven of the proteins recognized by antiserum against serum proteins had identical molecular weights and isoelectric points as serum proteins. Three of these proteins were ceruloplasmin, transferrin, and glycoprotein 2. In addition to the proteins immunoprecipitated by the two antisera, more than 60 other proteins were detected on two-dimensional gels of the total secretory proteins. We conclude that the Sertoli cell secretes many proteins, some of which are specific to the testis and others of which are similar to serum proteins.

Animals↗
PubMed1980

Visually evoked potentials to pseudorandom binary sequence stimulation. Preliminary clinical trails.

We report results using a new stimulus for clinical testing of visually evoked potentials (VEPs). The stimulus was the modulation of the luminance of a large unpatterned field by a temporal pseudorandom binary sequence. The stimulus was similar to Gaussian white noise in that a large number of sinusoidal harmonics were presented concurrently. It has the important advantage that conventional signal averaging techniques can be used to analyze the VEP. Abnormal VEP responses were obtained when the stimulus was applied to patients with minimal macular and optic nerve disease.

Evoked Potentials↗
PubMed1979

Chemical data: an essential tool in the regulation of drugs.

How the Bureau of Drugs laboratories and offices obtain chemical data from the scientific literature, from user complaints and product defect reporting systems, from the drug manufacturers, from analyses of drug samples collected from the market, and from analytical research are described. The chemical data thus educed have been used successfully in developing new analytical methods, in establishing better specifications of drug quality, in removing adulterated drugs from the marketplace, in successfully prosecuting purveyors of substandard drugs, and in general assuring that consumers are provided with safe and effective drugs of high quality.

Biopharmaceutics↗
PubMed1979

Characterization of the androgen receptor in nuclei of seminiferous tubules of the mature male rat based upon radioimmunoassay of endogenous levels of bound testosterone.

A macromolecular testosterone complex which was salt-extracted from nuclei isolated from seminiferous tubules of the adult male rat was investigated by quantifying the testosterone directly by RIA. The steroid-binding capacity of the complex was destroyed by heating at both 12 and 50 C, suggesting the presence of an extremely thermolabile complex. This tubular complex was shown to be similar to the radioactively labeled androgen receptor isolated from ventral prostatic nuclei by their coelution during adsorption chromatography, by their coleution during ion exchange chromatography, their similar migration rate (4-4.46S) on both sucrose and glycerol density gradients, and their similar slow dissociation at 0 C. These observations indicate that the tubular complex contains a high affinity androgen receptor and suggest that the direct measurement of testosterone in this complex by RIA may be useful in identifying its cellular distribution.

Animals↗
PubMed1975

Characterization and physiological validation of a radioimmunoassay for plasma testosterone in the male rat.

A radioimmunoassay (RIA) to measure testosterone concentration in the plasma of male rats was formalized, tested and physiologically validated. The procedure measured testosterone equally well, whether or not estimation of recovery and chromatographic purification preceded the RIA. The results were equivalent to those achieved by the method of competitive protein binding. No 17beta-hydroxy-5alpha-androstan-3-one was found in the plasma of male rats. Adrenalectomy did not significantly decrease plasma testosterone in either male or female rats. The simplified protocol met all requirements of precision, sensitivity, accuracy and specificity. A single investigator can analyze 1,000 plasma samples for testosterone in one week if necessary.

Animals↗