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Biomedical subjects

G Potashnik

Publications and source records attributed to G Potashnik.

At least 55 records · Page 3Linked to original sources
PubMed1987

Effects of dibromochloropropane and ethylene dibromide on biochemical events and ultramorphology of ejaculated ram spermatozoa in vitro.

The effects of dibromochloropropane (DBCP) and ethylene dibromide (EDB) on the function and ultrastructure of freshly ejaculated washed ram spermatozoa were assessed. These two compounds inhibited the collective motility of the sperm in a dose-dependent fashion when the sperm cells generated their energy either by mitochondrial respiration (2-deoxyglucose-treated sperm cells) or by the intact energy production system. DBCP and EDB inhibited the oxygen uptake by the sperm in a dose-dependent manner. No change in lactic acid accumulation and glucose utilization by the sperm cells was noted following DBCP and EDB addition. No change in the collective motility of the sperm was noted when DBCP or EDB were added to spermatozoa treated with the electron transfer inhibitor, antimycin A. Electron microscopy studies of sperm cells treated with DBCP revealed lesions in the plasma membrane adjacent to the acrosome and in the acrosomal membrane forming vesiculations. The inner membrane and the matrix space of the mitochondria were condensed following DBCP treatment, leaving a large mitochondrial peripheral space, compared with the control. EDB, at the concentration studied, caused no change in the ultramorphological structure of the sperm. DBCP was more potent, at least 4-fold, compared with EDB. An in vitro direct effect of DBCP and EDB on ram spermatozoa was established. It is suggested that quantitative measurements of sperm collective motility derived by different metabolic pathways can be used as an in vitro toxicological model for evaluation of toxicological and environmental factors affecting biological systems.

Animals↗
PubMed1987

Acid phosphatase levels in follicular fluids following induction of ovulation in in vitro fertilization patients.

Considerable evidence indicates that changes in acid phosphatase (AP) activity at the ovarian level play a role in the process of ovulation. In this study the concentrations of AP were determined in follicular fluids collected from follicles of 52 women at the time of laparoscopy performed in connection with an in vitro fertilization program. In each of the 52 women at least one ovum was harvested. Of the 52 ova, 28 cleaved in vitro, while in 24 ova cleavage was not seen. Levels of AP in follicular fluids of women whose ova did not cleave were significantly lower than those found in follicular fluids of women with at least one ovum undergoing cleavage: 0.45 +/- 0.14 (SE) and 4.78 +/- 0.37 Bess Lowry Units (BLU), respectively. Comparison of AP levels in follicular fluids of women who conceived (5) and women whose ova cleaved, but in whom pregnancy was not achieved (23), did not reveal significant differences: 5.87 +/- 1.29 and 4.55 +/- 0.35 BLU, respectively. Moreover, the enzyme level was typical for a woman and not for a follicle. Fluids of two different follicles of the same woman, when one ovum cleaved and one did not, showed similar AP levels. AP levels were high in all samples follicles of women in whom at least one ovum cleaved. These findings indicate that the presence of certain levels of acid phosphatase represents an important, albeit not the sole, condition for ovum maturation. Moreover, the follicular fluid levels of AP could serve as an indicator of proper timing of the follicular puncture in relation to the human chorionic gonadotropin injection (or the luteinizing hormone peak).

Acid Phosphatase↗
PubMed1987

Gonadotoxicity and kinetics of dibromochloropropane in male rats.

Adult male rats were injected with [3H]dibromochloropropane dissolved in dimethylsulfoxide containing about 10 X 10(6) dpm. Blood from the tail and 24-h urine samples were collected up to 2 days post-injection. Tissue samples were further taken from the kidneys, liver, spleen, adrenals, epididymis, seminal vesicles and testes 7 h and 7 days post-injection. The results demonstrate that there is no preference in labelling of the testes compared with other organs, and the kidney and liver may have an important role in the elimination of DBCP.

Animals↗
PubMed1987

Dibromochloropropane (DBCP): an 8-year reevaluation of testicular function and reproductive performance.

The current study summarizes an 8-year reassessment of testicular function and reproductive performance in 15 workers with dibromochloropropane (DBCP)-induced azoospermia and oligozoospermia. Recovery of spermatogenesis was observed in four oligozoospermic and three azoospermic men whose plasma follicle-stimulating hormone (FSH) concentration was normal during the whole period. A marked increase in FSH and luteinizing hormone concentrations above the upper limit of normal was found in the azoospermic workers who did not recover. No significant changes in FSH concentrations were detected in both recovered and nonrecovered oligozoospermic men. Testosterone levels of all patients were normal at all times. Paternal exposure to DBCP was not associated with increased risk of fetal malformations or spontaneous abortion.

Chemical Industry↗
PubMed1984

Antigenicity of sperm cells after freezing and thawing.

Freezing and thawing is thought to result in removal of spermatozoal membrane antigens. We investigated the presence of sperm antigens before and after freezing and thawing by means of the immunoperoxidase assay (IPAMA), sperm immobilization test (SIT), and separation of proteins by gel electrophoresis. The results of the IPAMA and SIT assays showed no difference in the membrane antigens before and after freezing and thawing. Analysis of surface proteins by gel electrophoresis demonstrated that freezing and thawing did not remove any particular group of proteins from the surface membrane of spermatozoa. According to the evidence of the three tests performed, there is no meaningful removal of antigens from the sperm cell surface membrane by the process of freezing, preservation, and thawing when carried out by the specific methods used. This work does not support the suggestion that in cases of immunologic incompatibility between spermatozoa and cervical mucus it would be possible to overcome the couple's infertility by employing the process of freezing, preservation, and thawing.

Antigens, Surface↗
PubMed1983

Comparison of post-thaw sperm motility after freezing in liquid nitrogen with protective media of either glycerol or glycerol-egg-yolk-citrate.

Thirty semen samples with a mean prefreezing motility of 70.4% were frozen for 1 month in liquid nitrogen by means of a modified Barkay's method and with either glycerol or glycerol-egg-yolk-citrate (GEYC) as protective media. The post-thaw motility was found to be 37.9% and 30.7% and cryosurvival rate (CSR) was 54.6% and 44.4%, respectively--the difference being significant (P less than 0.05). When samples achieving at least 40% of post-thaw-motility (PTM) in either medium were selected, the mean prefreezing motility increased to a 71.6%, and the PTM and the average CSR were 44.1% and 62.2% and 35.5% and 50%, respectively, when either glycerol or GEYC was used. It appears that glycerol alone is superior to a mixture of GEYC for cryo-preservation of sperm if the technique mentioned above is used and PTM is a criterion for sperm quality.

Citrates↗
PubMed1981

The exaggerated prolactin response to thyrotropin-releasing hormone and metoclopramide in 1,2-dibromo-3-chloropropane-induced azoospermia.

Twelve males with azoospermia secondary to exposure to the nematocide 1,2-dibromo-3-chloropropane were challenged to iv LRH (100 micrograms), TRH (200 micrograms), and metoclopramide (MET; 10 mg) administered 30 min apart. When compared to 24 male controls, both basal FSH and LH levels as well as peak gonadotropin responses to LRH were increased in the azoospermic group. The patients also had increased total estradiol (E2) and testosterone (T) as well as testosterone-binding globulins levels. Free T levels, however, were not significantly different from the controls. Basal PRL levels were similar in the two groups. However, the peak PRL responses to both TRH and MET were significantly increased in the azoospermia subjects (P < 0.001). In both groups, the PRL response to MET was greater than to TRH. In the individual control and azoospermic subjects, there was no correlation between the PRL response and E2, T, or the E2 to T ratio. However, a positive correlation did exist between testosterone-binding globulin levels and the PRL response to TRH and MET. Although the precise mechanism underlying the PRL hyperresponsiveness is unknown, it may be an estrogen-induced phenomenon.

Adult↗
PubMed1980

Hormonal responses to nasal application of synthetic gonadotropin-releasing hormone in amenorrheic patients pretreated with gonadotropins.

Synthetic gonadotropin-releasing hormone (GnRH) in the form of nasal drops was self-administered by five amenorrheic patients in an attempt to assess its therapeutic value in anovulatory infertility. After follicular maturation had been induced with human menopausal gonadotropins (HMG), a total daily dose of 7.5 mg of GnRH in the form of nasal drops was self-administered at 2-hour intervals for 6 hours on 3 consecutive days. In four patients, plasma luteinizing hormone (LH) levels were significantly elevated over a period of at least 8 hours. In three of these patients, in addition, there was a definite upward shift in the basal body temperature (BBT) curve, and uterine bleeding occurred 6 to 9 days after the first dose of GnRH. In the fourth patient, ovulation was induced as indicated by a biphasic BBT curve, a plasma progesterone level of 13 ng/ml, and a luteal phase of 15 days. In the remaining patient, there was a borderline LH response and no clinical response. It is concluded that GnRH, in the form of nasal drops, is effective in eliciting and maintaining elevated plasma LH levels in patients in whom follicular maturation has been induced with HMG. By obtaining ovulatory LH levels, such a regimen can lead to ovulation. In addition intranasal self-administration of GnRH is convenient and may provide an alternative route of administration for long-term therapy with this hormone.

Administration, Intranasal↗
PubMed1979

Bromocriptine in hyperprolactinemic amenorrhea: a possible early effect on ovarian steroidogenesis.

The effect of bromocriptine was studied in a 28-year-old cretin woman who presented with long-term untreated primary hypothyroidism, primary amenorrhea, hyperprolactinemia, and an enlarged pituitary fossa. Bromocriptine therapy lowered the plasma prolactin and caused an early rise in plasma 17 beta-estradiol levels and uterine bleeding, despite the failure of plasma gonadotrophins to respond to luteinizing hormone release hormone (LHRH) administration. Thus, it is suggested that bromocriptine may have an early direct effect on the ovary in hyperprolactinemic amenorrhea.

Adult↗
PubMed1979

Effect of dibromochloropropane on human testicular function.

Severe impairment of spermatogenesis was found in 18 (78%) of 23 workers after exposure to 1,2-dibromo-3-chloropropane (DBCP). Azoospermia associated with elevated plasma follicle-stimulating hormone was diagnosed in 12 workers whose exposure time to DBCP varied from 100 to greater than 6,000 h. Oligospermia and normal plasma follicle-stimulating hormone were found in six employees with exposure times between 34 and 95 h. Plasma luteinizing hormone, testosterone and thyroxine were within the normal range. Testicular biopsy showed selective atrophy of the germinal epithelium, intact Sertoli cells and normal appearance of Leydig cells. The mechanism and potential reversibility of these testicular changes are still to be evaluated.

Adult↗