Biomedical subjects

R R Tremblay

Publications and source records attributed to R R Tremblay.

168 records · Page 10Linked to original sources

PubMedDate not supplied

In vitro interactions of calmodulin with the ovine proacrosin-acrosin system.

The authors studied the interaction of calmodulin (CaM) with proacrosin and acrosin from ram spermatozoa. CaM binding evaluated by the [125I]-CaM overlay procedure was shown to occur preferentially with both proacrosin and acrosin in the presence of EGTA; in the presence of Ca2+, the interaction was less intense. Further studies with native proenzyme preparations showed that proacrosin activation at pH 7.1 or 8.0 was significantly accelerated in the presence of CaM and EGTA (t1/2 = 23 min vs. 55 min for EGTA alone at pH 7.1), but not in the presence of Ca2+ (t1/2 = 73 min). The enzymatic activity of acrosin towards benzoyl arginine paranitroanilide, however, was not significantly affected by CaM whether Ca2+ was absent or present. Finally, the authors demonstrated that acrosin hydrolyzed CaM rapidly and extensively in the presence of EGTA. These results indicate that CaM interacts in vitro with proacrosin and acrosin, and that acrosin can attenuate CaM activity through proteolysis. Whether these interactions also occur in vivo and are involved in some aspects of spermatozoa function remains to be determined.

Acrosin↗

PubMedDate not supplied

The concentration of immunoreactive prostate specific antigen is not decreased in viscous semen samples.

The concentration of immunoreactive prostate specific antigen (PSA) was determined in the seminal plasma of 79 men who were classified into 4 groups according to sperm characteristics: there were 3 groups with low viscosity sperm (normal, large or small volume) and one group with high viscosity and normal volume. PSA concentrations in the group with high viscosity were not significantly different from the group with low viscosity and normal or large volume. PSA was significantly increased only in the "small volume group" (p less than 0.01). These results show that absolute amounts of PSA are not decreased in seminal plasma with high viscosity and therefore are not the cause of abnormal liquefaction of the semen in these patients.

Antigens, Neoplasm↗

PubMedDate not supplied

Hydrophobic behavior of sciatin and transferrin on a size-exclusion column.

Sciatin and transferrin are very similar glycoproteins which differ slightly in their carbohydrate content. In two-dimensional gel electrophoresis, they have one different isoform at pI lower than 5.77. However, highly different elution profiles have been recorded following size-exclusion HPLC. The use of a I-125 silica gel column has thus provided convincing evidence that both proteins do not show exactly the same hydrophobic three-dimensional structure.

Animals↗

PubMedDate not supplied

Compromise in the treatment of hirsutism with flutamide.

The association of Flutamide (500 mg/day) and of a contraceptive pill has been proposed for the treatment of hirsutism but the efficacy of low doses of the antiandrogen as single medication has never been ascertained. Twelve adult hirsute women, aged 31-40 years, were therefore recruited because they were sterile following tubal ligation. Severity of hirsutism was evaluated according to Ferriman and Gallwey scale. After one year, 10 out 12 patients experienced a satisfactory control of their hirsutism with Flutamide dosages varying between 250 and 375 mg/day. The antiandrogen can thus be used at lower dosages than initially expected.

Adult↗

PubMedDate not supplied

Search for androgen response elements in the proximal promoter of the canine prostate arginine esterase gene.

We have demonstrated the binding of the recombinant DNA binding domain of the rat androgen receptor to a DNA sequence of the canine prostate arginine esterase gene and have determined the functional significance of this sequence in transient transfection experiments. One of the binding sites was localized to a region (-172 to -148 bp) containing the sequence AGGACAACAGGTGTT that has 73% homology with the prostate-specific antigen (PSA) androgen response element (ARE) found at a similar position in the PSA promoter. Competition experiments showed that the androgen receptor had an approximately 100-fold more affinity for the PSA ARE than for the arginine sequence at -172 to -148. Transient cotransfection of 5'-deletion mutants of the arginine esterase promoter and 5'-flanking sequences driving the activity of the reporter gene along with the rat androgen receptor expression vector yielded only negligible inductions of chloramphenicol acetyl transferase (CAT) activity when dihydrotestosterone (DHT) was added to the culture medium. The introduction of one to four repeats of the -172 to -148 sequence of the arginine esterase gene upstream of the basal promoter of the mouse p12 gene in p12.108 also resulted in a minimal induction of CAT activity compared with a 10-fold induction of PSA AREs under similar conditions. These results suggest that the regulation of the canine arginine esterase gene by androgens is most probably achieved by mechanisms that differ from the ones prevailing with the human PSA and kallikrein-2 (hKLK2) genes.

Androgens↗

PubMedDate not supplied

Potential involvement of kallikrein hK2 in the hydrolysis of the human seminal vesicle proteins after ejaculation.

We have recently demonstrated in liquefied human seminal plasma the presence of the novel kallikrein hK2 in association with protein C inhibitor (PCI) as a 75-kDa complex. In the present study, we showed that hK2, immediately after ejaculation, was recovered only in its free form but complex formation with PCI occurred rapidly thereafter and was completed within 10 minutes. That reaction required an enzymatically active kallikrein. In order to determine the patterns of hydrolysis of major seminal vesicle proteins, semenogelins and fibronectin were exposed to hK2 and to hK3 (prostate-specific antigen or PSA) and cleavage sequences were identified by N-terminal sequencing. Free hK2 was able to hydrolyze semenogelins and fibronectin in vitro. Most of cleavage sites were at the carboxyl-side of arginyl residues. Semenogelins were hydrolyzed to a similar extent by catalytic (and similar) concentration of either hK2 or PSA though no common cleavage sites was identified for both proteinases. Unlike semenogelins, fibronectin was hydrolyzed much more efficiently by hK2 than by PSA. These results show that hK2 is enzymatically active during a short period of time after ejaculation, that major seminal vesicle proteins can be the target of this proteolytic activity, and that hK2 and PSA have different substrate specificities.

Antibody Specificity↗