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J Kleinstein

Publications and source records attributed to J Kleinstein.

24 records · Page 2Linked to original sources
PubMed1980

Failure of oxytocin and lysine-vasopressin to stimulate prolactin release in humans.

In order to test a possible stimulatory effect of oxytocin and lysine-vasopressin on prolactin (PRL) release six female volunteers received either saline or 1 IU oxytocin (Syntocinon) i.v.. Blood sampling was performed at intervals over 90 minutes. Nine puerperae were treated with oral oxytocin (Sandopart) 50 IU t.i.d. for seven days. Nine other untreated postpartum women served as controls. Blood was collected before delivery and on subsequent postpartum days, and the milk volumes produced were estimated by increases in the babies' weight. In addition, seven volunteers received 5 or IU lysine-vasopressin (Vasopressin) i.m. Blood was withdrawn at regular intervals for 180 minutes, the urine volumes excreted in 30-minute intervals were measured and the clearance of free water calculated. Oxytocin failed to modify basal plasma PRL in the acute trial and in the post-partum women, and milk amounts produced were not influenced by treatment. Vasopressin did not change the PRL plasma profile despite a significant (p less than 0.05) reduction in the excretion of free water. Results indicate that neuropeptides are not implicated in the control of PRL release.

Arginine Vasopressin↗
PubMed1978

Solubilization of a mammalian beta-adrenergic receptor.

Binding sites for iodohydroxybenzylpindolol with characteristics of a beta2-adrenergic receptor have been identified in a crude membrane fraction from guinea-pig lung. The binding sites could be solubilized by treatment of the membrane fraction with digitonin. Upon solubilization receptors retain their beta2-adrenergic type as indicated by the rank order of potencies of agonists in binding-inhibition experiments. The solubilized receptors demonstrate a marked increase in affinity for agonists compared with particulate receptors whereas antagonist affinity remains unchanged. Solubilized receptors are insensitive to divalent cations (Mg2+, Mn2+, Ca 2+) which increase the potency of agonists for particulate receptors. The effects of Mg2+ can be reversed by Gpp(NH)p in particulate preparations; Gpp(NH)p is ineffective for the solubilized preparation. These experiments establish that beta-adrenergic receptors can be solubilized even from crude mammalian membrane preparations. They also show that the mammalian beta-adrenergic receptor in situ is under constraints with respect to agonist affinity and is modulated by divalent cations and guanyl nucleotides in the intact membrane.

Adenylyl Cyclases↗
PubMedDate not supplied

Estrogen induces expression of endometrial epidermal growth factor receptors before implantation.

PROBLEM: Pharmacological doses of 17 beta-estradiol increase epidermal growth factor binding to uterine membranes. METHODS: To determine whether physiological elevated E2 concentrations in the preimplantation phase of rabbits and preovulatory phase of women cause epidermal growth factor (EGF) receptor expression, we performed radioligand binding studies of endometrial membranes with [125I]-EGF. RESULTS: Unmated rabbits revealed a binding maximum (Bmax) of 514 +/- 197 fmol/mg protein for [125I]-EGF. The Bmax values increased significantly to 1424 +/- 430 fmol/mg on day 1 and to 2244 +/- 224 fmol/mg on day 2 after mating. On day 3 the Bmax values decreased to 1409 +/- 238 fmol/mg and on days 4 to 8 the binding maxima were not significantly different from the Bmax values of unmated rabbits. In ovariectomized rabbits a significant increase of [125I]-EGF-binding could be mimicked 12 and 18 h after the intramuscular injection of estradiol (40 micrograms/kg). The estradiol-induced increase of [125I]-EGF Bmax values was blocked by the parallel application of the antiestrogen tamoxifen. Progesterone (2 mg/kg) did not influence [125I]-EGF-binding to endometrial membranes. Membrane preparations of the human endometrium from the periovulatory phase bound significantly more [125I]-EGF compared to endometrium of the early proliferative phase. The expression of EGF receptor mRNA was localized in the epithelial cells of the human endometrium by in situ hybridization technique. CONCLUSIONS: These results provide insight into the regulation of the autocrine and paracrine factor EGF in the endometrium during the preimplantation period.

Adult↗
PubMedDate not supplied

Effect of anesthesia on sperm motility in gamete intrafallopian transfer.

The existence of a motility-inhibiting substance in human peritoneal fluid (hPF) has been demonstrated. The results of this study indicate that this factor from hPF is a heat-resistant, volatile molecule with a very small molecular mass (e.g., halothane, which is used for general anesthesia in laparoscopic GIFT). This may be the reason for the conflicting results concerning pregnancy rates in gamete intrafallopian transfer.

Anesthetics↗
PubMedDate not supplied

Acrosin activity of human spermatozoa by means of a simple gelatinolytic technique: a method useful for IVF.

Acrosin activity was determined using a gelatinolysis technique in 100-microliter semen aliquots of 114 patients (normozoospermia, n = 90; asthenozoospermia, n = 12; oligozoospermia, n = 10; polyzoospermia, n = 2) attending an in vitro fertilization (IVF) program. Halo diameter, halo formation rate, and a calculated acrosin activity index correlated significantly with the IVF rates (P = 0.0054, r = 0.396; P = 0.0009, r = 0.401; and P = 0.0003, r = 0.428, respectively). In cases where the halo diameter was < 10 microns and halo formation rate was < 60%, all patients were subfertile or infertile, that is, they showed poor or no fertilization in vitro, respectively. The assay demonstrated a relatively low sensitivity: 25.7% for halo diameter, 37.1% for halo formation rate, and 25.7% for acrosin activity index, respectively. This might be attributed to other sperm functional aspects, such as disturbed acrosome reaction or impaired zona binding.

Acrosin↗