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Biomedical subjects

E Bloch

Publications and source records attributed to E Bloch.

At least 19 recordsLinked to original sources
PubMed1992

Endogenous estradiol and progesterone concentrations in smokers on oral contraceptives.

The simultaneous effects of cigarette smoking and oral contraceptives on serum estradiol and progesterone levels were investigated in 114 premenopausal women. Serum 17 beta-estradiol and progesterone levels were measured by radioimmunoassay. In smokers, estradiol and progesterone levels were significantly lower (p less than 0.025). In smokers using oral contraceptives, estradiol and progesterone levels were the lowest (p less than 0.001 and p less than 0.01, respectively). The findings suggest that smoking and oral contraceptives independently lower serum estradiol and progesterone concentrations in premenopausal women and that the effects may be additive.

Adolescent↗
PubMed1990

The effect of mono(2-ethylhexyl) phthalate on Sertoli cell transferrin secretion in vitro.

We have examined the effect of mono(2-ethylhexyl) phthalate (MEHP) on the secretion of rat transferrin (rTf) by Sertoli cells (SC) in the presence and absence of FSH. Significant decreases in rTf secretion were observed in SC cultures exposed to 50 and 75 microM MEHP, in the absence of FSH. Treatment of SC with FSH (300 ng/ml) obviated this suppression of rTf secretion by MEHP. These findings indicate an effect of MEHP on rTf secretion by SC in vitro which could account for the testicular toxicity of MEHP in vivo.

Animals↗
PubMed1988

Alpha-anomeric DNA: beta-RNA hybrids as new synthetic inhibitors of Escherichia coli RNase H, Drosophila embryo RNase H and M-MLV reverse transcriptase.

Nuclease-resistant alpha-anomeric DNA:beta-RNA hybrids are inhibitors of Escherichia coli RNase H, and Drosophila embryo RNase H. RNase H activities were measured by polyacrylamide gel electrophoresis, employing a short substrate, (A)12:d[G-G-(T)12-G-G], or by acid-solubility techniques, using a long substrate, poly(A):poly(dT). Strand exchanges which could be responsible for the observed inhibition have been ruled out by S1 nuclease experiments and by using inhibitors which do not allow strand exchange. Our results suggest that RNase H, for which DNA:RNA duplexes are the natural substrates, binds to non-physiological alpha-DNA:RNA hybrids and is consequently inhibited. These hybrids also inhibit the RNA-dependent DNA polymerase activity of M-MLV reverse transcriptase, therefore appearing as potential inhibitors of at least two reverse transcriptase activities. However, the inhibitory effect of these hybrids with respect to M-MLV reverse transcriptase is also observed with the single-stranded alpha-DNA itself. Unexpectedly, polymerase activity is highly stimulated by alpha-oligos, analogous in their sequence to the beta primer used at a concentration unable to generate a detectable synthesis. These results suggest that the inhibition of reverse transcriptase activity with the alpha:beta may occur at different levels.

Animals↗
PubMed1988

Reproductive toxicity of 2,4-dinitrotoluene in the rat.

The present study was undertaken to evaluate the effects of the chemosterilant 2,4-dinitrotoluene (DNT) on the rat testis. Adult male rats were fed control, or 0.1%, or 0.2% DNT for 3 weeks. An ultrastructural study of the testes was performed, serum was assayed for testosterone and gonadotropins, and sperm reserve count was determined. A marked change in Sertoli cell morphology was found after 3 weeks of 0.2% DNT exposure. Varying sized vesicles associated with swollen mitochondria and distended endoplasmic reticulum were visible in cells from DNT-treated animals. Circulating levels of follicle stimulating hormone and luteinizing hormone were increased in 0.2% DNT-treated animals. Reduced weights of the epididymides and decreased epididymal sperm reserves were observed in DNT-treated animals. These results indicate that DNT is capable of inducing testicular injury, of directly or indirectly disturbing pituitary function, and of exerting a toxic effect at the late stages of spermatogenesis. These findings suggest that a locus of DNT action is the Sertoli cell, resulting in both inhibition of spermatogenesis and changes in testicular-pituitary endocrine activity.

Animals↗
PubMed1988

Reproductive toxicity of 2,4-toluenediamine in the rat. 3. Effects on androgen-binding protein levels, selected seminiferous tubule characteristics, and spermatogenesis.

In previous studies we demonstrated reduced fertility, arrested spermatogenesis, and diminished circulating testosterone levels in rats fed 0.03% 2,4-toluenediamine (TDA) for 10 wk. These studies were extended in three experiments by determining TDA effects on androgen-binding protein (rABP) production and on seminiferous tubule structure, and on early changes in testes morphology and spermatogenesis. In the first experiment, rats fed 0.03% TDA for 10 wk showed a 7- to 9-fold increase in rABP content in testicular cytosol or in media of cultured seminiferous tubules, a 4-fold increase in serum rABP, but a two-thirds decrease in epididymal rABP levels. Testes examination by transmission electron microscopy revealed degenerative changes in Sertoli cells with, where present, normal spermatocytes and spermatids. In the second experiment, 0.03% TDA fed for 4, 6, or 8 wk resulted in a doubling of testes/body weight ratios and a highly correlated 2.5- to 2.9-fold increase in seminiferous tubule fluid volume. An approximately 50% decrease in epididymal sperm reserves was found after 6 or 8 wk of TDA exposure. After 10 wk of exposure to 0.03% TDA, testicular weight was the same as in control-fed rats but seminiferous tubule fluid volume was still elevated. These changes in testicular characteristics indicate TDA effects on Sertoli cell function, on RABP release from the testes (and epididymides), and possibly on tubular fluid transport. In the third experiment, rats fed 0.06% TDA for 1 wk showed a 25% decrease in epididymal sperm content, reduced epididymal weight, and minor structural changes in Sertoli cells. After 3 wk of 0.06% TDA feeding, sperm counts were further reduced, and were accompanied by a dramatic increase in testes weight, intense fluid accumulation, and ultrastructural changes in Sertoli cells. No significant changes in serum testosterone levels were noted in the TDA-treated rats. The results of this third experiment demonstrate TDA toxicity on testicular spermatogenesis within 3 wk of TDA feeding. The within 3 wk of TDA feeding. The findings in this study suggest that the early inhibition of spermatogenesis by TDA is mediated through Sertoli cell damage.

Androgen-Binding Protein↗
PubMed1988

Involvement of apurinic sites in the synergistic action of alkylating and intercalating drugs in Escherichia coli.

The toxicity of the intercalating compounds 9-aminoellipticine (9AE) and isopropyl-oxazolopyridocarbazole (Ipr-OPC) were studied. The inhibitory effect of non-toxic doses of 9AE, which incises DNA at apurinic (AP) sites, or Ipr-OPC, which does not cleave DNA at AP sites, with non-toxic doses of the alkylating agent dimethylsulphate (DMS) on the growth of Escherichia coli strain AB1157, is additive. The same result has been observed with an exonuclease III mutant which has only 10% of the AP endonuclease activity. However, 9AE or Ipr-OPC display a synergistic toxic effect with a DMS concentration which allows 20% of E. coli AB1157 survival. This synergy is increased for 9AE in the AP endonuclease mutant when compared to the wild-type strain. Under identical conditions 9AE and Ipr-OPC have no synergistic effect on a mutant deficient in the enzymes which generate AP sites. Therefore AP sites are involved in the synergistic toxicity of DMS and the studied intercalating agents. However, the precise role of the interaction of intercalating agents with AP sites, either without cleavage (type 1 compounds) or with cleavage (type 2 compounds), in the observed effect remains an open question.

Alkylating Agents↗
PubMed1987

Effects of prenatal administration of mestranol and two progestins on testosterone synthesis and reproductive tract development in male rats.

The oestrogen mestranol (0, 0.01, 0.1 mg/kg body weight per day) and the progestins medroxyprogesterone-acetate and norethisterone (0, 2, 20 mg/kg body weight per day each) in sesame oil were intubated intragastrically daily during gestational days 14.5 through 19.5 to pregnant rats. Males were studied as 20.5-day-old foetuses and 4-month-old adults for serum testosterone and LH concentrations, in vitro testosterone synthesis, anogenital distance (foetuses only) and testes, seminal vesicle and ventral prostate weights. Administration of 0.1 mg mestranol decreased by 35 to 70% basal and LH-stimulated testosterone synthesis by both foetal and adult testes in vitro (P less than 0.01). Foetal body weights (P less than 0.05), but not anogenital distances, were significantly decreased. Testosterone content in adult sera was reduced significantly (P less than 0.05) to less than 50% of control. Testes, ventral prostate, seminal vesicle and epididymal weights were unaffected by treatment. Medroxyprogesterone acetate or norethisterone administration did not alter testes endocrine function in foetal or adult offspring. In a small number of rats, pregnant for 10.5, 14.5 or 18.5 days, [3H]ethinyloestradiol was intubated and foetal and placental tissue examined for appearance and content of radioactivity. Radioactivity was detected in 10.5, 14.5 and 18.5 days old placentas, and 14.5 and 18.5 days old foetal liver, gonads and external genitalia. With [3H]medroxyprogesterone acetate, radioactivity was localized in 14.5 day placenta and foetal tissues. Thin-layer chromatographic analysis showed most of the activity to migrate as authentic ethinyloestradiol or medroxyprogesterone acetate. These results demonstrate inhibition of testicular testosterone synthesis by mestranol, presumably by being transferred across the placenta and acting in the foetus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

The effect of intragastric administration of delta 9-tetrahydrocannabinol on the growth and development of fetal mice of the A/J strain.

Pregnant A/J mice were intubated with vehicle (sesame oil:Tween 80:water) or 60, 120, or 240 mg/kg of delta 9-tetrahydrocannabinol on Days 11 and 12, 12 and 13, or 13 and 14 (vehicle and 240 mg doses only) of gestation. Mice were killed on Day 20 of gestation, and examined for number of corpora lutea and live and resorbed fetuses. Fetuses were weighed and examined for gross external and internal malformations. Each treatment group consisted of a minimum of 10 litters with about 10 pups per litter. In a few groups the effects of feed deprivation on Day 12 or of glucocorticoid administration on Days 12 and 13 (positive control) were assessed. Intubation with vehicle or delta 9-tetrahydrocannabinol, or feed deprivation did not affect number of live fetuses, incidence of resorption, fetal weights, or gross malformations other than cleft palate. Intubation of delta 9-tetrahydrocannabinol on gestational Days 12 and 13 or 13 and 14 increased the mean frequency of cleft palate formation. The increase was 2- to 2.5-fold at the 240-mg dose, being significant (p = 0.05) in the Days 12 and 13 group. Cortisone acetate and corticosterone injection induced both resorption and cleft palate formation. Other developmental or reproductive parameters were not influenced by delta 9-tetrahydrocannabinol treatment. We conclude that delta 9-tetrahydrocannabinol administered by gavage during Days 12 and 13 of gestation retards normal palatal development.

Administration, Oral↗
PubMed1985

[Lipomyxosarcoma of the pulmonary veins extending into the left atrium. Repetitive surgical treatment].

The case reported here of a 54-year old woman with lipomyxosarcoma of the pulmonary veins successfully excised is the first in the literature. The initial symptoms were febrile left ventricular failure with pulmonary oedema and haemoptysis. The diagnosis was made by angiocardiography. The tumour was excised in two stages: cardiac first, under cardiopulmonary bypass, then thoracic with left pneumonectomy. Two years after surgery, the patient is in good condition without chemotherapy.

Female↗
PubMed1985

Reproductive toxicity of 2,4-toluenediamine in the rat. 1. Effect on male fertility.

Effects of 2,4-toluenediamine (TDA) on reproduction in adult male Sprague-Dawley rats were evaluated. Diets containing 0, 0.01 and 0.03% TDA were fed ad libitum to experimental animals for 10 wk. No signs of toxicity were found. Exposure to the high dose resulted in decreased mating frequency and an increase in infertile matings. Light-microscopic examination of the testes revealed reduced numbers of sperm in the seminiferous tubules and cauda epididymides. These results indicate that TDA is capable of reducing fertility and of exerting an inhibitory or toxic effect on spermatogenesis in the rat.

Animals↗
PubMed1985

Reproductive toxicity of 2,4-toluenediamine in the rat. 2. Spermatogenic and hormonal effects.

The present study was undertaken to evaluate the endocrinologic and spermatogenic effects of 2,4-toluenediamine (TDA) in the rat. Adult male rats were fed 0,0.01, and 0.03% TDA ad libitum for 10 wk. At the end of wk 10 and at 11 wk post TDA treatment, the animals were killed, and cauda epididymal sperm counts and reproductive organ weights were determined. Blood samples were obtained for analyses of testosterone and gonadotropins. Treatment with 0.03% TDA for 10 wk reduced the weight of the seminal vesicles and epididymides and reduced serum testosterone levels. Cauda epididymal sperm counts were decreased in animals treated with 0.03% TDA for 10 wk and in TDA-treated animals placed on normal diet for 11 wk. Serum luteinizing hormone (LH) concentrations were increased and weights of epididymides and testes were reduced in 0.03%-TDA-treated animals placed on normal diet for 11 wk. The results indicate that TDA exerts a toxic effect on spermatogenesis and appears to affect androgen action and production in the male rat. Since the males exhibited reduced cauda epididymal sperm counts 11 wk after 0.03% TDA treatment, it appears that TDA induced damage to the germinal components of the testes.

Animals↗
PubMed1979

Stridor in pediatric patients.

We have presented a classification scheme to help in evaluating the diagnosis of stridor in the pediatric patient. The correct diagnosis can usually be arrived at on the basis of a careful and complete history, physical examination, appropriate radiographic studies and bronchoscopy. The anesthesiologist should be aware of the problems associated with all these conditions. In every instance prompt establishment of an adequate airway is imperative.

Abscess↗
PubMed1977

Cortisol levels in amniotic fluid in prostaglandin F2alpha-induced midtrimester abortion.

Cortisol concentrations in amniotic fluid and maternal plasma were determined by a competitive protein-binding assay in 14 patients in the midtrimester of pregnancy before and after intra-amniotic administration of prostaglandin F2alpha. Samples were obtained at three-hour intervals until abortion or until the fetal heartbeat ceased. The mean plasma levels of cortisol increased from 324 +/- 173 ng. per milliliter at hour 0 to 524 +/- 272 ng. per milliliter at 6 hours (the peak elevated value). In amniotic fluid, the mean levels of cortisol increased from 4.71 +/- 2.5 ng. per milliliter to a maximum at 9 hours of 10.24 +/- 2.5 ng. per milliliter. We concluded that at 16 to 20 weeks' gestation the fetoplacental unit is capable of responding to prostaglandin F2alpha instillation by increased levels of cortisol in the amniotic fluid.

Abortion, Induced↗