Search PubMed⌕ Search

Biomedical subjects

A Krishna

Publications and source records attributed to A Krishna.

At least 91 records · Page 5Linked to original sources
PubMed1987

Increased number of mast cells in the dominant follicle of the cow: relationships among luteal, stromal, and hilar regions.

The number of mast cells per microscopic field at 450X (0.123 mm2) was determined in the bovine ovary on Days 4, 10, and 19 of the cycle (Day 0 = estrus). Mast cells were observed in the theca externa of follicles, the external capsule of the corpus luteum, and in the stromal and hilar regions of the ovary. The stromal and hilar regions exhibited the highest number of mast cells (per field = 7.51-10.15) compared with the follicular and luteal compartments (2.65-3.70 mast cells/field). Most interestingly, on Day 19 a significant increase in the number of mast cells was observed in the theca externa of the dominant follicle (10.4 mast cells/field) compared with nondominant healthy follicles on Days 4 and 10 (2-3/field). After ovulation, the number of mast cells surrounding the corpus luteum on Day 4 was significantly lower than 19 values in the dominant follicle; this was further diminished on Day 10 of the cycle. These results indicate that the increase in mast cells associated with the dominant follicle on Day 19 may be related to its development and the decline in mast cells related to ovulation.

Animals↗
PubMed1987

Effect of the gonadotrophin surge at pro-oestrus on steroidogenesis and gonadotrophin binding of preantral follicles in the cyclic hamster.

The present study describes the acute changes in steroids and human chorionic gonadotrophin (hCG) and FSH binding of preantral follicles induced by the gonadotrophin surges on the day of pro-oestrus. Preantral follicles were isolated by microdissection before (09.00-10.00 h), during (15.00-16.00 h) and after (21.00-22.00 h) the LH surge on pro-oestrus. Follicles at each time-period were pooled and steroid concentrations and gonadotrophin receptors determined. Before the LH surge, concentrations of progesterone and androstenedione were 40.8 +/- 6.1 (S.E.M.) and 10.7 +/- 3.9 fmol/follicle respectively. At the peak of the LH surge, progesterone and androstenedione concentrations in preantral follicles increased to 848 +/- 186 and 129 +/- 33 fmol/follicle respectively. Immediately after the LH surge, progesterone increased to 1238 +/- 97 fmol/follicle whereas androstenedione declined to 13.3 +/- 2.1 fmol/follicle. Oestradiol was less than 6 fmol/follicle throughout these periods. Binding of hCG and FSH to preantral follicles increased after the surge (hCG, 56 +/- 2.6 c.p.m./follicle; FSH, 29.8 +/- 4.0 c.p.m./follicle) when compared with values obtained before the surge (hCG, 15.8 +/- 4.0 c.p.m./follicle; FSH, 14.1 +/- 1.9 c.p.m./follicle). Also, hCG binding increased significantly (P less than 0.05) from 09.00 to 21.00 h (56 +/- 2.6 c.p.m./follicle). In order to ascertain which follicular compartments were affected by the LH and FSH surges on pro-oestrus, granulosa cells and thecae from preantral follicles were isolated and steroid concentrations and LH and FSH binding measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Androstenedione↗
PubMed1987

Relationships between LH stimulation in vitro and progesterone, androstenedione and cyclic AMP synthesis in preantral follicles of the cyclic hamster.

In-vivo changes in steroidogenesis in preantral hamster follicles following exposure to the LH surge could be mimicked by stimulation with exogenous LH in vitro. Luteinizing hormone given only during the first hour (media were changed every hour) of a 6-h incubation promptly increased the concentration of androstenedione and adenosine 3':5'-monophosphate (cAMP) in the media and this was followed by a gradual decline to less than 20% of the peak value; progesterone in media was not detectable with a single LH stimulation. However, LH given every hour increased progesterone and cAMP concentrations in the media throughout the period of incubation, but the transient increase and subsequent decline in androstenedione was still observed. The decline in androstenedione release by preantral follicles was apparently due to a lack of steroid precursor and not to either inhibition of hydroxyl-lyase or lack of LH or cAMP stimulation. Exogenous dibutyryl cAMP (dbcAMP) and 8-Br-cAMP mimicked the effects of LH on the pattern of follicular androstenedione release into the media; however, dbcAMP and 8-Br-cAMP did not increase concentrations of progesterone in vitro. In preantral follicles, LH stimulated cAMP release into the media and apparently inhibited phosphodiesterase activity, since methyl isobutylxanthine (MIX) did not potentiate the effect of LH on cAMP. Follicle-stimulating hormone also increased androstenedione and cAMP in the media of the preantral follicles in a manner similar to that of LH, except that between 4 and 6 h of incubation the release of androstenedione and cAMP was less than that produced by stimulation with LH.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-3-isobutylxanthine↗
PubMed1986

Histamine and increased ovarian blood flow mediate LH-induced superovulation in the cyclic hamster.

Constant infusion of LH (400 micrograms NIH-S24) through an osmotic minipump inserted on Day 1 (oestrus) of the cycle in the hamster resulted in spontaneous superovulation (approximately equal to 29 ova) at the next expected oestrus, increased blood flow (P less than 0.001) to the ovary on Day 3, and slight depletion (0.1 greater than P greater than 0.05) of histamine in the ovary. Treatment with antihistamine (alpha-fluoromethylhistidine, an irreversible inhibitor of histidine decarboxylase, or cimetidine, an H2 blocker) by injections or by infusion using separate osmotic minipumps significantly (P less than 0.01) reduced the number of ova shed in the LH-treated hamsters. Infusion of LH with alpha-fluoromethylhistidine in the same osmotic minipump reduced the bioactivity of the LH. Infusion of antihistamine alone did not alter the normal number of ova shed. The results suggest that the LH-induced superovulation involves stimulation of histamine release; the histamine than may increase ovarian blood flow thus allowing more gonadotrophins to reach the ovary.

Animals↗
PubMed1985

Antagonistic effect of progesterone towards estradiol dipropionate-induced changes in glycogen content in uterus and vagina of P-mice.

Estradiol dipropionate induces an increase (3-fold) in the uterine glycogen content and a decrease (4-fold) in the vaginal glycogen content of Parkes (P) mice. Progesterone antagonizes this estradiol dipropionate-induced response in both the uterine and vaginal tissue. The degree of this antagonism is more pronounced in the uterus than in the vagina.

Animals↗
PubMed1985

Alterations in mast cell degranulation and ovarian histamine in the proestrous hamster.

Mast cells in the ovary of cyclic hamsters were observed exclusively in the hilum and in the vicinity of blood vessels that enter and exit the ovary. Ovaries were collected on proestrus from hamsters at 0900 h preluteinizing hormone (LH) surge, 1500 h (peak LH surge), and 2100 h (post-LH surge) and processed for routine histologic staining with toluidine blue. A significant increase in the percentage of extensively degranulating mast cells was observed coincident with the gonadotropin surge (0900 h: 5.39 +/- 0.97%; 1500 h: 20.39 +/- 2.76%). At the peak of the LH surge the ovarian histamine concentration was also significantly higher than those before and after the surge (1500 h: 5.13 +/- 0.94 ng/mg ovary; 0900 h and 2100 h: 2.84 +/- 0.35 and 3.02 +/- 0.48 ng/mg, respectively). The results indicate that a major source of ovarian histamine may be mast cells residing in the ovarian hilum and surrounding the ovarian blood vessels that enter and exit the ovary. In addition, the gonadotropin surge on the day of proestrus may be a trigger for release of mast cell histamine.

Animals↗
PubMedDate not supplied

Aborted thoracopagus.

Explore the source record for details and available documents.

Diseases in Twins↗
PubMedDate not supplied

Pattern of ovarian protein synthesis and secretion during the reproductive cycle of Scotophilus heathi: synthesis of an albumin-like protein.

Ovarian proteins synthesized de novo and secreted in vitro were investigated during different stages of the reproductive cycle of Scotophilus heathi. We found increased ovarian protein synthesis and secretion during the recrudescence and the preovulatory periods, coinciding with two peaks of follicular development and steroidogenesis. The ovaries synthesized protein at a low rate during quiescence and the late phase of delayed ovulation. In vitro analysis using 35 S-methionine incorporation showed increased synthesis of 66 kDa protein during delayed ovulation, but secretion of this protein declined markedly during the preovulatory period. N-terminal sequencing of the 66 kDa protein showed that it shares 70% homology with human serum albumin. Immunocytochemistry indicated that this protein is found primarily in the granulosa cells of the follicles. Whether the increase in albumin production by the ovaries during delayed ovulation is associated with a hyperinsulinemic and hyperandrogenic condition requires further investigation.

Albumins↗