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T J Lobl

Publications and source records attributed to T J Lobl.

29 records · Page 2Linked to original sources
PubMed1982

Purification and characterization of androgen receptor from steer seminal vesicle.

The androgen receptor has been purified from steer seminal vesicle cytosol by a combination of differential DNA-Sepharose 4B chromatography and testosterone 17 beta-hemisuccinyl-3,3'-diaminodipropylamine-Sepharose 4B affinity chromatography. The procedure produced about 3 micrograms of receptor protein from 35 g of steer seminal vesicle, with a yield of 48%. The receptor protein, as a complex with unlabeled testosterone, was purified approximately 540000-fold. A single band, migrating at 60000 daltons, was observed following electrophoresis on a polyacrylamide gel containing sodium dodecyl sulfate (NaDoDSO4). This was confirmed by affinity labeling of the partially purified receptor with both 17-hydroxy-17 alpha-[3H]methyl-4,9,11-estratrien-3-one and 17 beta-hydroxy-[1,2,4,5,6,7,16,17-3H8)-5 alpha-androstan-3-one 17-(2-bromoacetate), which showed a peak of radioactivity migrating at 60000 daltons by NaDoDSO4 gel electrophoresis. The receptor had an estimated Stokes radius of 35 A and a sedimentation coefficient of 3.8 S in the presence of 0.3 M NaCl. The calculated molecular weight and frictional ratio for the androgen binding activity were 57000 and 1.42, respectively. Chromatofocusing of the purified receptor protein revealed an isoelectric point of 6.6. [3H]Methyltrienolone, bound to the purified receptor, was displaced with methyl-trienolone greater than testosterone greater than 5 alpha-dihydrotestosterone much greater than 3 beta-hydroxy-delta 5-androsten-17-one much greater than 5 alpha-androstane-3 alpha,17 beta-diol. The physicochemical properties of the purified receptor were similar to those of the receptor in crude cytosol. These results demonstrate that the androgen receptor from steer seminal vesicle was substantially purified without significant modification of its physicochemical or steroid binding properties.

Affinity Labels↗
PubMed1981

Steroid structural requirements for high affinity binding to human sex steroid binding protein (SBP).

The sex steroid binding protein (SBP) which binds androgens circulating in the blood of man has been examined to determine the structural requirements for high affinity binding. SBP was purified partially and the ability of each of more than 150 steroids to compete with [3H]dihydrotestosterone (17 beta-hydroxy-5 alpha-androstan-3-one) for binding to SBP was assessed. Binding was enhanced by reduction of the delta 4 double bond to 5 alpha-dihydro, addition of a methyl group at C-4 and in one case unsaturation at C-14,15. Affinity was always reduced by modifications of the C-17 beta hydroxy. Binding was also severely decreased by deletion of the keto moiety at C-3; however, relatively high affinity was retained by an alcohol or an unsubstituted pyrazole group at C-3. Certain alpha surface substitutions such as 17 alpha-ethinyl had limited effects on binding; whereas, other modifications such as 7 alpha-methyl or 17 alpha-methyl caused significant reduction in binding. Most modifications at C-2, 6, 9 or 11 also impaired affinity, and the 5 beta steroids had reduced affinity.

Androgen-Binding Protein↗
PubMed1981

Androgen transport proteins: physical properties, hormonal regulation, and possible mechanism of TeBG and ABP action.

The physical properties and hormonal regulation of testosterone estradiol binding globulin (TeBG) and androgen binding protein (ABP) are reviewed. Brief mention is made of prostatic binding protein. The discussion focuses on the mechanism of action for these proteins in androgen secretion, transport, and absorption and androgen binding models. Speculations are presented for the functional significance of these proteins.

Age Factors↗
PubMed1979

Characterization of the exfoliative antispermatogenic agent 1-(2,4-dichlorobenzyl)-H-indazole-3-carboxylic acid in the rhesus monkey.

The effects of oral doses of 1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid (DICA) on spermatogenesis in the rhesus monkey (Macaca mulatta) was studied. Four animals given five daily 50 mg/kg doses or three or five daily 500 mg/kg doses showed that DICA was an exfoliating antispermatogenic compound. The inhibition of spermatogenesis was only partially reversible following 500 mg/kg doses of DICA. Weekly and monthly 50 mg/kg doses of DICA only partially inhibiting spermatogenesis as measured by electro-ejaculated sperm counts. Response in individual monkeys ranged from azoospermia to no effect. Testicular biopsies confirmed this finding. DICA did not affect serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), or testosterone concentrations. The blood absorption or urinary excretion rates of uniformly tritiated DICA in the animals that responded well did not differ from those monkeys that responded poorly. DICA metabolites were not detected in monkey urine. Serum testosterone concentrations appeared to vary with the season of the year, but FSH concentrations and ejaculated sperm count did not.

Animals↗
PubMed1979

1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid (DICA), an exfoliative antispermatogenic agent in the rat.

The oral administration of 50 mg DICA/kg at nine weekly or four monthly intervals produced partially reversible infertility in male rats as judged by the results of serial mating and testicular histology. Oral 500 mg DICA/kg doses administered at the same intervals produced permanent sterility. Single oral doses of 50 or 500 mg DICA/kg elevated mean FSH concentrations on days 2, 3, and 7 but did not affect LH or testosterone. Mean plasma concentration peaked at 74 micrograms/ml 4 hr after a 50 mg/kg dose of uniformly tritiated DICA; 24 hr later, it had declined rapidly to 5.5 micrograms/ml. The drug did not have a strong affinity for any tissue studied including the testis. DICA-induced exfoliation of immature germ cells was first observed 4 hr after administration and led to significantly reduced testis weights by day 2. Neither single doses of 10--250 mg DICA/kg nor five daily doses of 10--100 mg DICA/kg reduced seminal vesicle, ventral prostate, or body weights of male rats. Chronic weekly DICA administration did reduce mean seminal vesicle weight. These studies have shown that DICA is an effective, partially reversible antifertility agent that directly affects the rat testis.

Administration, Oral↗
PubMed1979

Electron microscope study of 1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid, an exfoliative antispermatogenic agent, in the rat testis.

We were interested in discovering whether the antifertility agent, DICA [1-(2,4-dichlorobenzyl)-1-H-indazole-3-carboxylic acid] induced Sertoli cell tight junction damage. Testis were fixed in 1% lanthanum nitrite cacodylate-buffered 2% gluteraldehyde at various times following a single oral 100 mg/kg dose of DICA. In control animals adluminal lanthanum was never seen. At one and ten days following DICA treatment adluminal lanthanum was seen. This suggests that the Sertoli cell tight junctions are more permeable to lanthanum following DICA treatment.

Androgen-Binding Protein↗
PubMed1978

Effect of 1-(2,4-dichlorobenzyl)-indazole-3-carboxylic acid on sperm tails in rhesus monkeys.

Large numbers of spermatozoa with bent or coiled tails were found in the ejaculates of rhesus monkeys treated with 1-(2,4-dichlorobenzyl-indazole-3-carboxylic acid (DICA) (50 or 500 mg/kg for various periods). The defect appeared only in spermatozoa in the cauda epididymidis and consisted of axoneme disarrangement and loss of the fibre doublets. The coil was completely enclosed in a membrane.

Animals↗
PubMedDate not supplied

A technique for rapid purification of low yield products: biotinylation of chemically synthesized proteins on-resin.

We report here straightforward methodology for the purification of chemically synthesized proteins which are produced in low yield. The methodology is generally applicable to all proteins still on-resin and fully protected except for the terminal amino group. The protein is treated in order with the following steps: Biotinylation with NHS-biotin, HF cleavage, and avidin-agarose affinity chromatography. No special skills or automated equipment are needed to take advantage of this procedure.

Avidin↗