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Biomedical subjects

M C Chang

Publications and source records attributed to M C Chang.

At least 271 records · Page 15Linked to original sources
PubMed1976

Temporal changes in circulating steroids during prostaglandin F2alpha induced abortion in the rat and rabbit.

The serum levels of progesterone (delta4P), 20alpha-dihydroxyprogesterone (20alpha-DHP), pregnenolone (delta5P) and estrogens at different time intervals during Silastic-PVP-PGF2alpha tube induced midterm abortion were measured by radioimmunoassay in the rat and rabbit. The concentrations of delta4P and delta5P were significantly reduced but that of 20alpha-DHP was increased significantly as early as 20 hours after PGF2alpha treatment. Estrogen levels showed slight reduction in the rat but remained unchanged in the rabbit. The ratio of delta4P/20alpha-DHP recorded were 2.15 and 16.86 (pretreatment) and dropped to 0.08 and 0.37 (60 hours after insertion of Silastic-PVP-PGF2alpha tube) in the rat and rabbit, respectively. These findings suggest that the suppression of circulating delta4P by PGF2alpha might be the result of a reduced precursor (delta5P) pool size as well as changes in the enzymic systems responsible for the formation and conversion of delta4P. It is still to be determined if changes in estrogen levels in the rat have any bearing on abortion induced by PGF2alpha.

Abortion, Induced↗
PubMed1976

Relationship between oestrogen, prostaglandin F2alpha and histamine in delayed implantation in the mouse.

Treatment of pregnant mice ovariectomized on day 3 (23.00-2330 h) with progesterone (1 mg/day/mouse, from day 4 through 11 post coitum (p.c.)) and oestrogen (single injection of 0.05 mug on day 8 p.c.) induced implantation in all the animals. Implantation was inhibited in animals following three subcutaneous injections of indomethacin given on the morning and afternoon of day 8 and the morning of day 9 p.c. A single injection of histamine on day 8 p.c. partially compensated the effect of indomethacin. A complete reversal of the antifertility effect of indomethacin was achieved following intraperitoneal administration of histamine (2 mug at noon of day 8 p.c.) and PGF2alpha (20 mug on the morning and afternoon of day 8 p.c.). This study suggests that in the mouse uterus indomethacin impairs the physiological changes which are required for the decidual cell formation and implantation. It is likely that an injection of oestradiol in the progesterone treated ovariectomized mice triggers the release of PGF2alpha and histamine and that these compounds are involved in the chain of events leading to implantation of blastocysts.

Animals↗
PubMed1976

In-vitro fertilization of hamster eggs in different media and the stimulating effect of heterologous and homologous spermatozoa.

Hamster eggs with follicular cells were fertilized by epididymal spermatozoa in two chemically defined media. The proportion of penetrated eggs was significantly higher in a medium for rabbit (16%) than in a medium for rat eggs (6%), but much lower than in Tyrode's solution containing follicular fluid or blood serum as reported by others. The optimal sperm concentration for sperm penetration ranged from 0.5 to 5 X 10(6)/ml but penetration of denuded eggs failed in these media. When exposed to hamster spermatozoa in the rabbit medium containing living or dead spermatozoa of guinea-pig, rat, mouse or hamster, high proportions of denuded eggs (24-96%) and eggs with follicular cells (93%) were penetrated. By exposure of denuded hamster eggs to hamster spermatozoa in supernatant fluid of frozen-thawed guinea-pig spermatozoa, 97% of eggs were penetrated in 8 hr compared to 0% in the control group. Sperm capacitation was also efficiently induced by preincubation of hamster spermatozoa in the supernatant fluid. The fertilizing capacity of hamster spermatozoa was maintained for 12 hr during incubation with frozen-thawed guinea-pig spermatozoa when the concentration of hamster spermatozoa ranged between 10 and 20 X 10(6)/ml. The beneficial factor of guinea-pig spermatozoa appeared to be from spermatozoa themselves, not from the vasal or epididymal fluids. The presence of follicular cells, blood serum, bovine serum albumin, or even polyvinylpyrrolidone in the media is essential for the capacitation and acrosome reaction of hamster spermatozoa. The components of guinea-pig spermatozoa appear to maintain the fertilizing capacity of hamster spermatozoa and stimulate the process of capacitation.

Animals↗
PubMed1976

Reproduction in rats and mice isoimmunized with homogenates of ovary or testis with epididymis, or sperm suspensions.

Female rats and mice were injected with homologous spermatozoa without adjuvant, or with homogenates of ovary or testis+ epididymis in adjuvant. Ovulation was not inhibited and the numbers of eggs released were normal. Fertilization rates were significantly reduced in the mouse by all tissues injected and in the rat by injection of ovarian homogenate only. Fracture of and a weak precipitate on the zona pellucida of the eggs were observed in the mouse but not in the rat after injection of ovarian homogenates. The number of pregnancies and litter sizes were reduced following the first and second mating after treatment in the mouse but not in the rat. When eggs with or without follicular cells were examined in vitro, fertilizability was very low if the donor had been treated with ovarian homogenate, better with testis+epididymis homogenate and best after treatment with sperm suspension. Failure of fertilization appeared to be the major cause of infertility after such treatments.

Animals↗
PubMed1976

Fertilizing ability in vivo and in vitro of spermatozoa of rats and mice treated with alpha-chlorohydrin.

The fertilizing ability of epididymal spermatozoa from rats and mice treated for 3 or 4 or 9 or 10 days with various doses of alpha-chlorohydrin was tested in vitro, and in vivo by intrauterine insemination. The minimum doses (per kg/day) needed to affect fertilization significantly were: rat, in vitro, 8-8 mg for 3 or 4 days, 4-4 mg for 4 days and 2-7 mg for 9 or 10 days; in vivo, 4-4 mg for 3 or 4 days and 2-7 mg for 9 or 10 days: mouse, in vitro, 4-4 mg for 3 days and 13-3 mg for 9 days; in vivo, 44-2 mg for 3 days and 26-5 for 9 days. Rats were infertile for at least 18 days after receiving 44-2 mg alpha-chlorohydrin/kg/day for 3 days, but fertilizing ability, tested in vivo and in vitro, was restored 10-11 days and 15-18 days, respectively, after daily treatment with 11-1 mg alpha-chlorohydrin/kg for 3 days.

Animals↗
PubMed1976

The fertilizing capacity of epididymal spermatozoa in relation to age, body weight and the onset of sexual maturity in the golden hamster.

Experiments with prepubertal hamsters were undertaken to determine if the appearance of spermatozoa with fertilizing capacity in the cauda epididymidis is related to age and/or body weight and whether the development of sperm function coincides with complete maturation of the mating behaviour pattern. At Week 6 after birth, intrauterine insemination of comparable numbers of spermatozoa showed that fertilizing capacity was related to body weight and not to age or seminal vesicular fructose concentration. In contrast to the low fertilization rate produced by spermatozoa from males weighing 80 g at Week 6 after birth, spermatozoa from 80-g males at Week 7 showed normal fertilizing capacity. Only 50% of 7-week-old males weighing 100-110 g produced fertile matings whereas all matings were fertile with males weighing 135 g and with males weighing 100 to 110 g that had received 7 consecutive daily injections of 50 mug testosterone beginning at Week 6 after birth. Comparison of sperm numbers in the cauda epididymidis and ductus deferens after mating at Week 7 showed that males which produced sterile matings were unable to terminate intromission with normal ejaculation of spermatozoa.

Aging↗
PubMed1975

In vitro fertilization of rat and mouse eggs by ejaculated sperm and the effect of energy sources on in vitro fertilization of rat eggs.

In vitro fertilization of rat and mouse eggs by ejaculated or epididymal spermatozoa in chemically defined media was studied. Penetration rates by ejaculated sperm was very low (0 to 8%) in the rat, but 11 to 41% of eggs were penetrated by ejaculated sperm in the mouse. The optimal concentration of sperm for in vitro fertilization appears to be similar whether ejaculated or epididymal sperm were used. The time of sperm penetration in the mouse eggs, however, was delayed for one-half to one hour when ejaculated sperm were used. The importance of sodium pyruvate, sodium lactate and glucose in the medium containing bovine serum albumin for in vitro fertilization of rat eggs was examined. When rat eggs in cumulus clot were exposed to epididymal sperm preincubated for five hours, the presence of sodium pyruvate, sodium lactate and glucose was found to play an important role. When exposed to non-incubated epididymal sperm sodium pyruvate could be omitted without much decline of the fertilization rate. When the denuded eggs were exposed to non-incubated sperm, penetration rates were very low (0 and 5%) in the absence of pyruvate. It appears that although lactate, pyruvate and glucose are all important for in vitro fertilization of rat eggs, pyruvate can be supplied by the follicular cells surrounding the eggs.

Animals↗
PubMed1975

Induction of temporary sterility in female hamsters by an intraperitoneal silastic-PVP-PGF2alpha tube.

In the female hamster, temporary sterility for a period of 10 or 15 days was induced by an intraperitoneal Silastic-PVP-tube containing 3.5 or 1.0 mg of PGF2alpha, respectively. All Silastic-PVP-PGF2alpha tube hearing animals regained fertility and delivered normal litters at various times after the placement of the tube. The release rate of 3-H-PGF2alpha from the Silastic-PVP tube was described and their potential use as a drug delivery system discussed.

Animals↗
PubMed1975

Prostaglandin F2alpha: modification of its abortifacient effect by depo-estradiol cypionate in rats.

Insertion of a Silastic-PVP implant containing 150 mug PGF2alpha into one of the uterine horns or administration of a single subcutaneous injection of 4 mug of Depo-Estradiol Cypionate (ECP) did not induce abortion in pregnant rats. However, a combined treatment with 150 mug of PGF2alpha in a Silastic-PVP implant and 4 mug of ECP induced abortion in all treated rats. Apparently, ECP stimulated endogenous production of PGF and consequently enhanced the effect of the administered 150 mug of PGF2alpha. The release of 3H-PGF2alpha from Silastic-PVP implants was faster after intrauterine or intraperitoneal than after subcutaneous insertion. The release rate of 3H-PGF2alpha from Silastic-PVP implants in vitro was comparable to that observed after subcutaneous placement of similar implants. It is suggested that administration of estrogen combined with PGF2alpha might shorten the interval between treatment with PGF2alpha and abortion. Moreover, a Silastic-PVP implant would lend itself as a better method of administration, releasing PGF2alpha locally, slowly, and continuously.

Abortifacient Agents↗