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Biomedical subjects

V Hansson

Publications and source records attributed to V Hansson.

At least 217 records · Page 12Linked to original sources
PubMed1977

Metabolism of testosterone in the human prostate and seminal vesicles.

Tissue from the normal, hyperplastic and the cancerous human prostate as well as tissue from the human seminal vesicles are capable of metabolizing testosterone in vitro. By incubating minced tissue with 3H-testosterone for 2 hours at 37 degrees C the following radioactive metabolites were identified: testosterone (17 beta-hydroxyl-4-androsten-3-one), androstenedione (4-androstene-3,17-dione), androstanedione (5alpha-androstane-3,17-dione), 5alpha-dihydrostestosterone (17 beta-hydroxy-5alpha-androstane-3-one, DHT), 3alpha-androstanediol (5alpha-androstane-3alpha,17beta-diol), 3beta-androstanediol (5alpha-androstane-3beta-17beta-diol) and androsterone (3alpha-hydroxy-5alpha-androstane-17-one). When normal human prostatic tissue was incubated with 3H-testosterone approximately 40% of the hormone was metabolized and 30-35% of the metabolites were identified as DHT. There were apparently no differences in testosterone metabolism between the dorsal and lateral prostatic lobes. A much lower conversion of 3H-testosterone was observed in the seminal vesicles (24%). The same metabolites were formed by prostatic carcinoma tissue, although distinctive quantitative differences from the normal prostate were observed. Thus, only 23% of the testosterone was metabolized by cancerous tissue of which 15% was present as DHT. The formation of 17-keto metabolites and androstanediols in the prostatic carcinoma tissue was approximately the same as in the normal prostatic tissue. The most extensive metabolism of testosterone was found by incubation of tissue from benign nodular prostatic hyperplasia. About 65% of the testosterone was metabolized, and 40% of the metabolites were identified as DHT. Hyperplastic prostatic tissue also showed a significantly higher formation of 5alpha-androstanedoils and the other tissues examined. The high formation of DHT and 5alpha-androstanediols in benign nodular prostatic hyperplasia in comparison with normal and cancerous prostatic tissue and seminal vesicle tissue might indicate that these metabolites should be studied more closely as possible aetiological factors for prostatic hyperplasia. The very low metabolism of testosterone in prostatic carcinoma tissue should be examined further in relation to tumour differentiation and clinical effect of endocrine therapy.

Adenocarcinoma↗
PubMed1976

Androgen metabolism by rat epididymis. 5. Metabolic conversion and nuclear binding after injection of 5alpha-androstane-3alpha, 17beta-diol, in vivo.

The pattern of androgenic metabolites in blood, muscle, caput and cauda epididymidis has been investigated in functionally hepatectomized 24 hours castrated rats, 3 hours after the intra-muscular injection of 200 muCi of 3H-3H-3alpha-diol. Identification of the radioactive metabolites showed only negligible differences between the epididymal regions. In both caput and cauda the main metabolite was DHT (17beta-hydroxy-5alpha-androstane-3-one); 3alpha- and 3beta-diol, androsterone (3alpha-hydroxy-5alpha-androstane-17-one), 5-A-dione (5alpha-androsterone-3, 17-dione), delta16-3alpha-01 (kalpha-androst-16-en-3alpha-01), delta16-3beta-01 (5alpha-androst-16-en-3alpha-01) and delta16-3-one (5alpha-androst-16-en-3-one) were also present. Androsterone and 3alpha-diol were the predominant metabolites in blood and muscle. No delta16 compounds could be detected and in constrast to epididymis, more than 50% of the radioactivity was associated with polar compounds. From determination of total radioactivity, it was seen that retention by epididymis varied from two to four times that of muscle. Purification and identification of the radioactivity associated with the nuclear fraction demonstrated that DHT was the only nuclear bound androgen. It is suggested from these results that at least one effect of 3alpha-diol on the rat epididymis is exerted through its conversion to DHT.

Androstane-3,17-diol↗
PubMed1976

Further characterization of the androgen receptor in rat testis.

Immature rat testes contain a specific binding protein for testosterone (T) and 5alpha-dihyrotestosterone (DHT) with physico-chemical properties similar to the cytoplasmic androgen receptors in the epididymis and ventral prostate but different from the testicular androgen-binding protein (ABP). Like the androgen receptors in the prostate and epididymis, it has a sedimentation coefficient of about 7 S at low ionic strength, is eluted in or close to the void volume on Sephadex G-200 gel filtration (Stokes radius greater than 80 A), has an isoelectric point of about 5.6-6.0 (mean) 5.8 and a relative mobility (Rf) of 0.4 in 3.25% acrylamide gels. Following the injection of 3H-labeled testosterone, T and DHT are bound selectively by the receptor. Relatively more [3H]T than [3H]DHT is present in bound and free fractions as well as in total testicular 105,000 g supernatant. Similar results are obtained from testicular incubations with equimolar amounts of [3H]T and [3H]DHT at 0 degrees C in vitro. Saturation of receptor sites is achieved by incubation of testis supernatants with increasing amounts of [3H]T at 0 degrees C. The number of available binding sites following post-hypophysectomy regression is estimated to be about 9 fmoles/mg protein, and the apparent equilibrium constant of dissociation is 7 X 10(-10) M. The temperature stability and sulfhydryl dependence of the testicular androgen receptor are similar to androgen receptors in other organs. Binding is destroyed by heating the supernatants at 50 degrees C for 30 min and by exposure to p-chloromercuriphenylsulfonate (1 mM) at 0 degrees C for 60 min. Furthermore, like other androgen receptors, the half-time of dissociation of testicular androgen-receptor complexes at 0 degrees C is extremely slow (t1/2 greater than 35 h). Separation of seminiferous tubules from interstitial tissue showed that a major portion of these receptors were localized within the seminiferous tubules.

Animals↗
PubMed1976

Hormones and hormonal target cells in the testis.

Studies over the last few years have greatly increased our knowledge about target cells for sex hormones and gonadotropins in the testis. A diagram illustrating our present state of knowledge is given in Fig. 1. LH is the principle stimulus of testosterone secretion by the Leydig cells. Direct effects of estrogens and androgens on these cells might modulate the response to LH. Androgens are apparently influencing the differentiation and the contractility of peritubular cells. FSH is the principle stimulus for Sertoli cell secretory function before puberty, although androgens are acting synergistically with FSH. After puberty, androgens alone are capable of maintaining on optimal secretory function of the Sertoli cells. In addition to normal secretory activity of the Sertoli cells, direct stimulation of the germ cells by androgens is needed in order maintain spermatogenesis.

Age Factors↗
PubMed1976

Androgen receptors in the anterior pituitary and central nervous system of the androgen "insensitive" (Tfm) rat: correlation between receptor binding and effects of androgens on gonadotropin secretion.

The cytosol fractions of the anterior pituitary, hypothalamus, preoptic area and brain cortex of androgen "insensitive" (Tfm) rats possess androgen receptors. However, in the Tfm rats the androgen binding per mg protein was only 10-15% of that in the corresponding normal littermates (Nl). The physicochemical properties of the androgen receptors in the anterior pituitary of the Tfm rat were indistinguishable from those of the normal rat. Thus, no distinctive differences were observed with regard to electrophoretic mobility in 3.25% polyacrylamide gels, isoelectric point (pI=5.8), binding affinity (KD=1.5 X 10(-9)M), temperature stability, sulfhydryl dependence and steroid specificity. It is, therefore, likely that the very low androgen binding capacity by the anterior pituitary and the central nervous system is due to an extreme reduction in the receptor number rather than to the presence of abnormal receptors. Since in the Tfm animals the androgen receptor number is reduced by 85-90%, it is to be expected that very high doses of androgens would be required to achieve hormonal effects. In fact, low doses of 5alpha-dihydrotestosterone propionate (50 mug/100 g body weight) given sc daily for 12 days had no effect on serum levels of LH and FSH. However, very high doses (2 mg/100 g body weight) of testosterone propionate and 5alpha-dihydrotestosterone propionate, which maintained circulating androgen levels above 20 ng/ml, significantly reduced serum gonadotropin levels in castrated Tfm rats. In normal littermates both low and high doses of the androgens suppressed gonadotropin secretion to low levels. These findings strongly indicate that androgen receptors are essential to androgen action on the anterior pituitary and central nervous system in the rat. The serum levels of testosterone (7.7+/-0.15 (SE) ng/ml) and 5alpha-dihydrotestosterone (0.37+/-0.06 ng/ml) were significantly higher in intact Tfm rats than in normal littermates (2.6+/-0.03 and less than 0.1 ng/ml, respectively). The failure of the elevated concentrations of serum androgens to reduce the high serum levels of LH and FSH in intact Tfm rats is most likely due to the extreme reduction of the androgen receptor number and the consequent insufficient hypothalamic and/or pituitary response to androgens.

Adrenal Glands↗
PubMed1976

Popliteal pterygium syndrome in a 74-year-old woman.

The case of a 74-year-old woman with the rare popliteal pterygium syndrome is presented. This syndrome is inherited as an autosomal dominant trait with incomplete penetrance and varying expression and consists of cleft lip and palate, lip pits, genital anomalies, popliteal pterygium, and malformations of the extremities. The various treatments our patient underwent over the years are reported. Treatment of popliteal pterygium involves special problems whem removing the skin fold because the nerve and vascular cords lie immediately anterior to the posterior fibrous cord. In the present case there are widespread arthrotic changes, both in the extremity joints and in the spine. These patients are short in stature. This, together with the general arthropathy, suggests a hereditary metabolic disturbance in the cartilaginous tissue.

Abnormalities, Multiple↗
PubMed1976

Secretion and role of androgen-binding proteins in the testis and epididymis.

The Sertoli cell appears to be a target cell for both FSH and androgen. FSH stimulates the Sertoli cell to produce an androgen-binding protein (ABP) which may serve to increase the accumulation of androgen in the seminiferous tubular epithelium and make it available for binding by intracellular androgen receptors. This might be one way by which FSH enhances the action of androgen on spermatogenesis. Androgen acts on the Sertoli cell to increase its response to FSH resulting in increased production of ABP and of other substances which exert trophic effects on spermatogenesis.

Androgens↗
PubMed1976

Androgen receptors in male sex tissues of rats and humans.

A brief description of physicochemical properties of the androgen receptors in the various target tissues is given. It is suggested that androgen receptors in all organs and species are very similar if not identical. It is also suggested that apparent differences in steroid binding are not due to differences in steroid specificity of receptors, but rather due to organ specific differences in target tissue metabolism. A short discussion of our studies on androgen receptors in the prostate, epididymis and testis of human being is also included. The properties of these receptors are similar, if not identical to those described in rats, and we have not been able to demonstrate differences in androgen receptors of non-neoplastic and neoplastic tissue. From studies on testosterone metabolism it is demonstrated that human prostate is metabolizing testosterone to DHT much faster than the seminal vesicles. Furthermore, there is a drastic reduction in DHT formation in tissue from prostatic cancer compared to normal and hyperplastic prostatic tissue.

Androstane-3,17-diol↗
PubMed1975

Testicular androgen binding protein (ABP) - a parameter of Sertoli cell secretory function.

Using ABP as an index of Sertoli cell secretory function, several important features of the Sertoli cell have emerged: 1. The stimulation of ABP production by FSH clearly points to the Sertoli cell as a target cell for FSH (3,4,9-16,21,24). 2. The dramatic effects of androgens on ABP production both in immature and mature rats also suggest that the Sertoli cell is a target cell for androgen (3,12,14,16,25). 3. The striking reduction in ABP production in the cryptorchid testis raises the question whether impairment of Sertoli cell function is the primary reason for the loss of germ cells that occurs in this condition (20). 4. Drugs like nitrofurazone or ethionine, or X-irradiation only slightly affect the secretory function of the Sertoli cells (ABP production), indicating that these treatments most probably have direct effects on the germ cells as well. Thus, measurement of ABP production rate is a very important tool in order to evaluate how hormones, drugs and physical injuries might affect the secretory function of the Sertoli cell. This test system might be of great use in order to study the physiology and hormonal regulation of the Sertoli cells. It might also be valuable in pharmacological and toxicological studies.

Age Factors↗
PubMed1975

Purification and characterization of rabbit testicular androgen binding protein (ABP).

Testicular androgen binding protein (ABP) was purified from the epididymis of 1500 adult rabbits by the sequential use of ammonium sulphate precipitation, ion exchange chromatography on DEAE cellulose, gel filtration on Sephadex G-200, hydroxyl-apatite chromatography and preparative polyacrylamide gel electrophoresis. This procedure yielded a 1000-fold increase in specific activity compared to that of the 1500,000 x g supernatant, and the recovery of active ABP was about 3-5%. ABP is acid glycoprotein with a molecular weight of 65-68,000 daltons. Antisera to rabbit ABP raised in quinea pigs inhibit 3H-DHT binding to ABP as measured by SS-PAGE. When diluted rabbit serum containing TeBG is treated with the same dilutions of these antisera, identical binding inhibition curves are found. Thus, ABP and TeBG in rabbits appear to possess identical immunological determinants.

Amino Acids↗
PubMed1975

Androgen receptor in nuclei of rat testis.

Testis nuclei of hypophysectomized rats selectively accumulate labeled testosterone and 5alpha-dihydrotestosterone following the injection of tritiated testosterone in vivo. Testosterone and 5alpha-dihydrotestosterone are bound to macromolecules in nuclei and can be extracted with 0.5 M KCl. Accumulation of protein bound radioactive androgens in nuclei of isolated seminiferous tubules is similar to that of whole testis. The relative amounts of testosterone and dihydrotestosterone in purified nuclei were similar to the relative amounts bound to cytoplasmic receptors, suggesting that cytoplasmic androgen-receptor complexes may be transported into the nuclei. Binding of labeled androgen is saturable and inhibited by prior injection of unlabeled testosterone or cyproterone acetate. Nuclear binding sites are destroyed by the proteolytic enzyme pronase, but not by DNase. Like the cytoplasmic androgen-receptor complexes in rat testis, nuclear androgen-protein complexes are heat labile and dissociate slowly at 0 degrees C. androgens fail to accumulate in testis nuclei of the Stanley-Gumbreck androgen insensitive rat, a species lacking cytoplasmic androgen receptors in testis and other androgen target tissues.

Animals↗
PubMed1975

Sertoli cell origin of testicular androgen-binding protein (ABP).

In this report it is suggested that the specific adrogen-binding protein (ABP), previously shown to originate in the testis of rat and other species, is produced by the Sertoli cells. This suggestion is based upon the following experimental findings: 1) ABP was found in high concentrations in testicular efferent duct fluid but only in trace amounts in inter-tubular lymph. i) ABP could be recovered from crude preparations of testis tubules, but not from Leydig cells from the same testes. 3) Testes whose germinal epithelium had been severly damaged by gamma irradiation showed no decrease in ABP content. The transport of ABP to epididymis was also preserved as judged from the levels of ABP in caput epididymis. 4) Testes that were completely devoid of germ cells following prenatal gamma irradiation showed high levels of ABP, These high levels approached zero following hypophysectomy, but could be restored by FSH administration to the hypophysectomized animals. ABP has been well characterized and now provides a valuable experimental tool as an indicator of Sertoli cell function.

Animals↗