Search PubMed⌕ Search

Biomedical subjects

S Kamada

Publications and source records attributed to S Kamada.

81 records · Page 5Linked to original sources
PubMed1980

Subunit structure of erythrocruorin from the polychaete Tylorrhynchus heterochaetus.

Sodium dodecyl sulfate (SDS)-gel electrophoresis of erythrocruorin from the polychaete Tylorrhynchus heterochaetus revealed the presence of four subunits with molecular weights of 12,000, 22,000, 23,500, and 54,000 in a molar ratio of 6 : 1 : 2 : 3, respectively. The largest subunit dissociates into polypeptide chains of 13,500 molecular weight in the presence of mercaptoethanol, whereas each of the other subunits consists of a single polypeptide chain. Hemochromogen determination gave a minimum molecular weight of 26,500 per mol of heme group. A model of the subunit structure of the erythrocruorin molecule is proposed, composed of 144 subunits (252 polypeptide chains) possessing 144 heme groups. The molecular weight of the erythrocruorin was calculated to be 3.636 x 10(6).

Animals↗
PubMedDate not supplied

Does endothelin-1 affect human spermatozoa function?

PROBLEM: It has been reported that massive amounts of immunoreactive endothelins (ETs) exist in human seminal plasma. However, the physiological role of ETs in seminal plasma remains to be determined. We speculated that ETs might affect sperm function. METHOD: The present study was designed to investigate the effect of endothelium-1 (ET-1) on: (a) sperm motion parameters, (b) hyperactivated motility, (c) sperm-zona pellucida-binding capacity, (d) sperm-oocyte penetration capacity, (e) acrosome reaction and its prerequisite, an increase in intracellular Ca2+ concentration ([Ca2+]i), and to examine (f) the presence of binding sites for ET-1 in human sperm. Forty-six semen ejaculates from 14 fertile men were assessed under capacitating conditions after separation of the motile sperm fraction by wash and swim-up. RESULTS: ET-1 (1 micron) exhibited significant stimulatory effects on sperm velocity at 30 min (P = 0.01), amplitude of lateral head displacement (ALH)max (P = 0.05), and ALHmean at 60 min (P = 0.04) in some samples (n = 10). However, these effects were not observed in experiments using a larger number of samples (n = 39). ET-1 had no effect on hyperactivated motility of sperm at 30 min to 24 h. Neither ET-3 nor IRL 1620, a selective ETB receptor agonist, affected sperm motion parameters or hyperactivated motility. ET-1 did not affect sperm-zona-binding capacity, sperm-oocyte penetration capacity, acrosome reaction, or [Ca2+]i of sperm. Specific binding sites for ET-1 were not detected on the cell surface of human sperm. CONCLUSIONS: Although ET-1 is present in massive amounts in human seminal plasma and may have the capacity to alter the quality of motile sperm in some samples, a physiological role of ET-1 in the modulation of the function of mature, ejaculated sperm still remains unknown.

Acrosome↗
PubMedDate not supplied

Combined therapy with bromocriptine and clomiphene citrate for patients with normoprolactinemic amenorrhea.

The purpose of this study was to investigate the combined effect of bromocriptine (Brc) and clomiphene citrate (Cl) treatment on 40 patients with normoprolactinemic amenorrhea who failed to respond to Cl alone. The ovulation rate in this treatment was 57.3% (23/40) in the 40 cases, 55.6% (99/178) in 178 cycles; the pregnancy rate was 26.7%. This treatment was effective in 14 of 21 women with polycystic ovary-like syndrome (66.7%). Among those women who responded to treatment, prolactin (PRL) and LH levels were significantly decreased. Estradiol and progesterone levels were significantly increased in the patients who responded. Before treatment, the responsiveness of LH to LHRH among responders to Brc/Cl therapy was significantly higher than among the nonresponders. After treatment, the LH-releasing response following a conjugated estrogen injection in the patients who responded to the treatment was significantly greater than that in the patients who did not respond. The results suggest that the therapeutic effect of this treatment may be primarily due to the restoration and improvement of the impaired hypothalamo-pituitary axis.

Adolescent↗