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Biomedical subjects

N A Klein

Publications and source records attributed to N A Klein.

At least 37 records · Page 2Linked to original sources
PubMed1996

Decreased inhibin B secretion is associated with the monotropic FSH rise in older, ovulatory women: a study of serum and follicular fluid levels of dimeric inhibin A and B in spontaneous menstrual cycles.

UNLABELLED: This study sought to compare circulating and follicular fluid (FF) concentrations of dimeric inhibin A and B utilizing specific two-site ELISAs for these hormones in normal older and younger ovulatory women. METHODS. Normally ovulating women age 40-45 (n = 10) and 20-25 (n = 13) were studied throughout the follicular phase with daily blood sampling, transvaginal ultrasound examinations, and dominant follicle aspiration. When the dominant follicle reached a mean diameter of 16 mm or serum estradiol (E2) was > or = 550 pmol/L, 10,000 IU of hCG was administered intramuscularly followed 32 hours later by transvaginal follicle aspiration. Serum and FF samples were analyzed for E2, FSH, and inhibin A and B. Daily hormone levels were compared by ANOVA, and mean results were compared using t-tests. RESULTS: Older women developed a dominant follicle sooner, meeting criteria for hCG cycle day 10.6 +/- 0.4 vs. 14.5 +/- 1.0 p < 0.001. As expected, the older group had higher maximal serum FSH concentrations compared to the younger women (11.4 +/- 0.5 vs. 8.0 +/- 0.4 IU/L, p < 0.001). We compared hormone concentrations from days-1 to 3 (where day 0 = day of maximal FSH concentration). E2 concentration was higher in the older women (p = 0.002), and there was no significant difference in inhibin A secretion (p = 0.61). In contrast, mean inhibin B concentration was significantly lower in the older women (p = 0.04). On the day of aspiration of the dominant follicle, serum inhibin B was decreased in the older subjects (42.6 +/- 6.5 vs. 153.1 +/- 53 pg/ml, p = 0.02), whereas older subjects had higher levels of inhibin A (106 +/- 16 vs. 60.4 +/- 9.4 pg/ml, p = 0.04) and similar E2 levels (665 +/- 35.2 vs. 687 +/- 92 pmol/L, p = 0.83). There were no differences in FF concentrations of inhibin B (164 +/- 31 vs. 174 +/- 37 ng/ml, p = 0.85), inhibin A (317.7 +/- 38 vs. 248 +/- 57 ng/ml, p = 0.16), or E2 (2074 +/- 294 vs. 2474 +/- 338 nmol/L, p = 0.82) in the older and younger women. CONCLUSION. Follicular phase inhibin B secretion is decreased in older ovulatory women who demonstrate a monotropic FSH rise, whereas inhibin A secretion is similar to that in younger women. The dominant follicle in these older women appears to be normal in terms of FF E2 and inhibin content. We speculate that decreased inhibin B secretion most likely reflects a diminished follicular pool in older women and may be an important regulator of the monotropic FSH rise.

Adult↗
PubMed1996

The anterior pituitary response to a gonadotropin-releasing hormone challenge test in normal older reproductive-age women.

OBJECTIVE: To assess the pituitary responsiveness to GnRH stimulation of premenopausal women relative to age. DESIGN: Older and younger reproductive-age women underwent the GnRH stimulation test in the early follicular phase of the menstrual cycle. SETTING: Female subjects in an academic research environment. PATIENTS: Women aged 21 to 44 years consisting of normal volunteers and infertility patients. INTERVENTIONS: Gonadotropin-releasing hormone was administered intravenously between days 2 and 4 of the menstrual cycle. Blood samples were collected from -20 minutes before to 120 minutes after administration. MAIN OUTCOME MEASURE: Luteinizing hormone, FSH, inhibin, and E2 levels. RESULTS: No significant difference in baseline values existed between older and younger women with regard to LH, inhibin, and E2, but basal FSH levels were higher in older women. A significantly diminished percent of LH and percent FSH change above baseline occurred 30 minutes after GnRH administration in the older women compared with younger women. No change in inhibin or E2 levels could be detected during the sampling period. CONCLUSIONS: The present study demonstrates marked attenuation of the acute pituitary LH response (sensitivity) to GnRH stimulation in older women when compared with a younger cohort.

Adult↗
PubMed1995

Partial characterization of K(+)-induced increase in [Ca2+]cyt and GnRH release in GT1-7 neurons.

Secretion of pituitary gonadotropins is regulated centrally by the hypothalamic decapeptide gonadotropin releasing hormone (GnRH). Using the immortalized hypothalamic GT1-7 neuron, we characterized pharmacologically the dynamics of cytosolic Ca2+ and GnRH release in response to K+-induced depolarization of GT1-7 neurons. Our results showed that K+ concentrations from 7.5 to 60 mM increased [Ca2+]cyt in a concentration-dependent manner. Resting [Ca2+]cyt in GT1 -7 cells was determined to be 69.7 +/- 4.0 nM (mean +/- S.E.M.; n = 69). K+-induced increases in [Ca2+]cyt ranged from 58.2 nM at 7.5 mM [K+] to 347 nM at 60 mM [K+]. K+-induced GnRH release ranged from about 10 pg/ml at 7.5 mM [K+] to about 60 pg/ml at 45 mM [K+]. K+-induced increases in (Ca2+]cyt and GnRH release were enhanced by 1 microM BayK 8644, an L-type Ca2+ channel agonist. The BayK enhancement was completely inhibited by 1 microM nimodipine, an L-type Ca2+ channel antagonist. Nimodipine (1 microM) alone partially inhibited K+-induced increases in [Ca2+]cyt and GnRH release. Conotoxin (1 microM) alone had no effect on K+-induced GnRH release or [Ca2+]cyt, but the combination of conotoxin (1 microM) and nimodipine (1 microM) inhibited K+-induced increase in [Ca2+]cyt significantly more (p < 0.02) than nimodipine alone, suggesting that N-type Ca2+ channels exist in GT1-7 neurons and may be part of the response to K+. The response of [Ca2+]cyt to K+ was linear with increasing [K+] whereas the response of GnRH release to increasing [K+] appeared to be saturable. K+-induced increase in [Ca2+]cyt and GnRH release required extracellular [Ca2+]. These experiments suggest that voltage dependent N- and L-type Ca2+ channels are present in immortalized GT1-7 neurons and that GnRH release is, at least in part, dependent on these channels for release of GnRH.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1994

Cytokine regulation of cellular proliferation in endometriosis.

OBJECTIVE: This study was designed (1) to characterize the resident leukocyte population in ectopic endometrium (EE), (2) to assess proliferative activity of cellular components in EE, (3) to assess whether resident leukocytes in EE express IFN gamma mRNA and (4) to demonstrate endometrial epithelial cell IFN gamma receptors in EE. STUDY DESIGN: Biopsies of EE and normal eutopic endometrium (UE) were studied immunocytochemically using monoclonal antibodies specific for CD45 leukocyte common antigen, CD3 (a T cell marker), CD11c (a macrophage marker), and Ki67 (proliferation marker). Leukocyte types were identified immunocytochemically, followed by in situ hybridization to assess expression of IFN gamma mRNA. IFN gamma receptor expression was assessed by immunocytochemistry. RESULTS: The percentage of scattered stromal cells staining for each CD marker was greater in EE than in UE. The proliferative activity of endometrial stromal cells and epithelial cells was significantly less in EE than in UE. The overall concentration of T cells and macrophages expressing IFN gamma mRNA was significantly greater in EE than in UE. The percentage of each leukocyte type expressing IFN gamma mRNA was also greater in EE than in UE, and IFN gamma receptors were present in glandular epithelium of EE. CONCLUSIONS: These findings support a possible paracrine role for resident leukocytes and IFN gamma in regulating cell proliferation in endometriosis.

Adult↗
PubMed1994

Serum progesterone concentrations on the day after human chorionic gonadotropin administration and progesterone/oocyte ratios predict in vitro fertilization/embryo transfer outcome.

PURPOSE: In gonadotropin-releasing hormone analogue-pretreated in vitro fertilization-embryo transfer cycles, pregnancy rates are inversely related to serum progesterone levels on the day of administration of human chorionic gonadotropin. The relationship of the progesterone concentration on other days in the periovulatory period to pregnancy rates in such cycles is little studied. We therefore retrospectively analyzed the relationship between progesterone concentrations on the day after human chorionic gonadotropin and pregnancy in 114 cycles, 28 and 23 of which produced clinical and ongoing/delivered pregnancies, respectively. To assess the effect of the extent of follicular luteinization on success, we also studied the relationship between the progesterone concentration per oocyte retrieved and pregnancy for the day of and day after human chorionic gonadotropin. RESULTS: Progesterone concentrations on the day after human chorionic gonadotropin were inversely associated with clinical pregnancy by multiple logistic regression analysis (P < 0.05). Progesterone/oocyte ratios were inversely associated with clinical pregnancy (P < 0.05) and ongoing/delivered pregnancy (P < 0.02) for both the day of and the day after human chorionic gonadotropin. CONCLUSION: The study results extend the window of time during which elevated progesterone concentration is associated with poor outcome to at least 2 days. This finding is consistent with hypothetical mechanisms attributing the link between progesterone concentration and outcome to either endometrial or follicle/oocyte events. The association of lack of follicular luteinization (low progesterone per oocyte ratios) and favorable outcome suggests a predominant effect of progesterone on follicle/oocyte quality. Further studies are needed to clarify the mechanisms underlying the association between progesterone and in vitro fertilization-embryo transfer outcome.

Adult↗
PubMed1994

Understanding volunteer peer health educators' motivations: applying social learning theory.

We conducted focus group interviews with students who were current peer health educators at a mid-sized university to determine what factors motivate individuals to volunteer for a peer health education program. Specifically, we asked the participants questions designed to explore their life experiences, their expectations of the peer education program, and their motivations. Constructs from social learning theory were used to categorize and contribute to our understanding of the responses. Many participants specified experiences with family members or friends, such as alcoholism or other illnesses, that had influenced their decisions. Participants' expectation of the program varied greatly and did not indicate a strong link to the decision to volunteer. The peer health educators' motivations for volunteering were altruistic, such as wanting to help others; egotistic, such as wanting job training; or related to self-efficacy beliefs, such as satisfying a personal need for health education. This study indicated that life experiences, a belief in the effectiveness of peer health education programs, and positive reinforcement to join influence the decision to volunteer. Implications for coordinating peer education programs are discussed.

Adolescent↗
PubMed1994

Evaluation of sex education curricula: measuring up to the SIECUS guidelines. Sex Information and Education Council of the U.S.

Most sexuality education curricula developed the past 20 years were not thoroughly evaluated. This study provides results from a content analysis of 10 sexuality education curricula for junior and senior high school students. Nine nationally available sexuality education curricula and one curriculum guide comprised the sample. The basis for analysis was the Guidelines for Comprehensive Sexuality Education, developed by the Sex Information and Education Council of the U.S. (SIECUS) and an instrument developed to measure bias in the curricula. Trained coders found that Sex Respect and Teen Aid addressed less than half the topics suggested by the SIECUS guidelines. Several of the curricula contained gender and sexual orientation bias. Certain key concepts such as "Sexual Behavior" and "Society and Culture" were not adequately addressed by most of the curricula. Findings indicate that of 10 curricula, only six are considered acceptable for educating junior and senior high school students.

Adolescent↗
PubMed1992

Mechanisms of insulin inhibition of ACTH-stimulated steroid secretion by cultured bovine adrenocortical cells.

Results of previous studies indicated that insulin at levels comparable to those in humans during hyperinsulinemia decreased ACTH-stimulated cortisol and androstenedione secretion by bovine adrenal fasciculata-reticularis cells in primary culture. In the present studies this inhibitory action was examined further by comparing the effects of insulin on ACTH-stimulated corticosteroid secretion with its effects on 8-(4-chlorophenylthio)-cAMP (cpt-cAMP), forskolin- and [5val]angiotensin II (Ang II)-stimulated corticosteroid secretion. Effects on corticosteroid secretion were correlated with effects on cAMP accumulation and rates of cAMP production. Monolayers were incubated for 24 h in the absence or presence of each agonist alone or in combination with insulin. Insulin (1.7 x 10(-9) or 17.5 x 10(-9) M) caused about a 50% decrease in cortisol and androstenedione secretion in response to ACTH (10(-11) or 10(-8) M). Insulin also decreased ACTH-stimulated aldosterone secretion by cultured glomerulosa cells. Cpt-cAMP (10(-4) or 10(-3) M)-stimulated increases in cortisol and androstenedione secretion were inhibited by insulin, but to a lesser extent than those in response to ACTH. The inhibition of cpt-cAMP-stimulated steroid secretion was not related to increased degradation of the cyclic nucleotide. Increases in cortisol and androstenedione secretion caused by a submaximal concentration (10(-6) M) of forskolin were decreased 50-70% by insulin. In contrast, insulin failed to significantly affect cortisol or androstenedione secretion caused by a maximal concentration (10(-5) M) of forskolin. The secretory responses to Ang II (10(-8) M) were also unaffected by insulin. The effect of insulin to inhibit ACTH-stimulated steroid secretion was accompanied by a reduction in cAMP accumulation as well as an apparent inhibition of adenylate cyclase activation. These data indicate that the effect of insulin to attenuate ACTH-stimulated corticosteroid secretion results from both an inhibition of ACTH-stimulated adenylate cyclase activity and an antagonism of the intracellular actions of cAMP.

1-Methyl-3-isobutylxanthine↗
PubMed1992

Consecutive versus alternating cycles of ovarian stimulation using human menopausal gonadotrophin.

Ovarian stimulation is an effective treatment for patients with ovulatory dysfunction and unexplained infertility. An initial report has suggested that consecutive cycles of ovarian stimulation can be employed without causing a diminished response in the second cycle. However, this observation has neither been confirmed nor has a regimen of consecutive stimulation cycles been compared to one of alternating stimulation cycles. Accordingly, 44 consecutive and 54 alternating cycles of stimulation were evaluated in patients (n = 42) who were treated with human menopausal gonadotrophin (HMG) alone. Human chorionic gonadotrophin (HCG) 10,000 IU was administered i.m. when at least one follicle exceeded 16 mm in mean diameter, and this was followed by either intercourse or intrauterine insemination. Using each patient as her own control, we were unable to demonstrate any differences in mean HMG dose requirements, endocrine parameters or follicular development on the day of HCG administration, or ovulation rates in the second consecutive cycle compared to the second alternating cycle. Clinical pregnancies resulted significantly more often in a consecutive cycle (8/22) than in an alternating cycle (2/27, P = 0.029). We conclude that consecutive cycles of ovarian stimulation with HMG are not detrimental and may, in fact, result in increased cycle fecundity compared to alternating stimulation cycles.

Adult↗
PubMed1991

Herpes simplex virus hepatitis in pregnancy. Two patients successfully treated with acyclovir.

Two cases of herpes simplex virus hepatitis in pregnancy are presented. Each case was characterized by extremely high serum aminotransferase levels with minimal bilirubin elevation. In both cases, liver biopsy was instrumental in arriving at the diagnosis. In addition, computed tomography showed a radiographic appearance of the liver not characteristically seen in other hepatic disorders of pregnancy. A high index of suspicion in the second case led to early recognition and treatment. Despite the presence of fulminant liver failure and evidence of herpes encephalitis in the other case, institution of therapy with acyclovir was associated with complete recovery in both patients. The present cases are compared and contrasted with the literature. The incidence of two cases within a 6-month period suggests that herpes simplex virus hepatitis in pregnancy may occur more frequently than previously reported.

Acyclovir↗
PubMed1982

Comparison of oral propranolol and verapamil for combined systemic hypertension and angina pectoris. A placebo-controlled double-blind randomized crossover trial.

The relative efficacies of oral verapamil, a calcium-entry blocking drug, and propranolol, a beta-adrenergic blocking drug, were compared in 12 patients who had both stable angina pectoris and mild to moderate systemic hypertension, using a placebo-controlled, double-blind, randomized crossover protocol. Compared with placebo, both propranolol and verapamil decreased the frequency of anginal attacks and the number of nitroglycerin tablets consumed, and increased exercise duration and total work; there were no significant differences in the antianginal effect of the two drugs. Both verapamil and propranolol reduced the supine and standing systolic and diastolic blood pressure measured at rest; compared with propranolol, however, verapamil had greater effects on standing diastolic blood pressure (p less than 0.002). Resting heart rate was reduced from placebo baseline with large doses of both drugs; compared with verapamil, however, propranolol exerted greater effects on resting heart rate and rate-pressure product. Plasma renin activity was increased from placebo baseline with verapamil (p less than 0.05), but was reduced with propranolol (p less than 0.05); no significant change in plasma aldosterone was seen with either drug. Verapamil appears to be a safe and effective treatment alternative to propranolol for relieving anginal symptoms, improving exercise tolerance, and reducing elevated systemic blood pressure in patients with both angina pectoris and mild to moderate systemic hypertension.

Adrenergic beta-Antagonists↗
PubMed1982

Long-term amrinone therapy in patients with severe heart failure: drug-dependent hemodynamic benefits despite progression of disease.

Six patients with severe congestive heart failure refractory to conventional therapy, including vasodilators, were treated with oral amrinone for a mean duration of 41 weeks (range 20 to 72 weeks). At initiation of therapy, the cardiac index increased from 1.74 +/- 0.31 to 2.62 +/- 0.52 (mean +/- SD) liters/min/m2 (p less than 0.01) and pulmonary capillary wedge pressure decreased from 26.5 +/- 3.5 to 19.5 +/- 5.4 mm Hg (p less than 0.05). Symptoms were alleviated and exercise capacity increased from 5.9 +/- 2.9 to 11.5 +/- 4.5 minutes (p less than 0.05). During long-term therapy, exercise capacity remained constants in three patients whereas it decreased in three others. All patients demonstrated an increase in heart size. Withdrawal of amrinone therapy precipitated severe symptoms at rest and hemodynamic deterioration in all patients. The cardiac index decreased from 1.87 +/- 0.49 to 1.32 +/- 0.30 liter/min/m2 (p less than 0.05) and pulmonary capillary wedge pressure rose from 20.6 +/- 2.9 to 28.8 +/- 5.6 mm Hg (p less than 0.05). These changes were reversed by reinstitution of therapy. Thus, amrinone-dependent hemodynamic benefits were demonstrated during long-term therapy without tachyphylaxis. In addition, progression of the underlying cardiac disease was observed in every patient.

Administration, Oral↗
PubMed1981

Exercise testing soon after uncomplicated myocardial infarction. Prognostic value and safety.

Modified exercise testing within three weeks of an acute myocardial infarction has been shown to be both a safe and feasible means for identifying patients at greater risk for subsequent cardiac events. An abnormal ECG and symptomatic response to exercise correlates with a higher morbidity and mortality. An ST-segment depression as well as angina are associated with a higher risk of recurrent ischemia and death. Elevation of the ST segment as well as inappropriately high heart rates and early development of fatigue and dyspnea are seen in patients with compromised left ventricular function. Exercise-induced premature ventricular contractions raise the possibility of increased sudden death. Patients identified to be at increased risk can be considered for more intensive medical or surgical treatment to reduce their morbidity and mortality. Patients considered to be at low risk can be spared needless invasive studies and unwarranted restriction of their physical activity. Patients may also accrue psychological benefit from these stress-test procedures.

Adult↗
PubMed1981

Hemodynamic comparison of intravenous amrinone and dobutamine in patients with chronic congestive heart failure.

Amrinone, a new inotropic agent, has been shown to be beneficial in patients with congestive heart failure. However, its hemodynamic effects have not been compared with those those of currently useful catecholamines. In this study, the effects of intravenously administered dobutamine and amrinone were compared in eight patients with severe chronic congestive heart failure. Dobutamine was infused with a maximal increase in cardiac index was reached for undesirable effects were produced. This dose was then continued for 8 hours. After a return of hemodynamic values to baseline level, amrinone was infused at a rate of 40 microgram/kg per min for 1 hour and then 10 microgram/kg per min for 24 hours. Both drugs significantly improved cardiac index while simultaneously decreasing systemic vascular resistance and right atrial and pulmonary wedge pressures (p less than 0.05). Initially no differences could be found between the drugs. However, with prolonged infusion amrinone produced a sustained improvement whereas dobutamine had a decreased effectiveness. Thus, amrinone is comparable in effect with the optimal dose of dobutamine and would appear to be an extremely promising drug in the acute treatment of severe congestive heart failure.

Adolescent↗
PubMedDate not supplied

The gonadotropin secretion pattern in normal women of advanced reproductive age in relation to the monotropic FSH rise.

OBJECTIVE: Women of advanced reproductive age are known to demonstrate subtle FSH elevations (monotropic FSH rise) while still retaining ovulatory function. The purpose of this study was to investigate the hypothesis that the physiologic basis for the monotropic FSH rise is an alteration in the secretion pattern of the GnRH pulse generator. METHODS: The subjects were 11 normal women age 40-45 years who underwent 24 hours of frequent blood sampling in the follicular (EF) and/or midluteal (ML) phases of spontaneous menstrual cycles. The controls were 11 normal women age 20-25 years. The respective gonadotropin secretion patterns were analyzed for LH pulse frequency, mean LH and FSH levels, and LH pulse amplitude. RESULTS: There were no differences between the groups for estradiol (E2) and progesterone when the respective cycle phases were compared. The 24-hour mean FSH level was significantly increased in the older women in both the EF and ML phases. There were no differences between the groups in either cycle phase for LH pulse frequency, LH pulse amplitude, and mean LH levels. CONCLUSION: The results lend no support to the hypothesis that a slowing or other alteration of the GnRH pulse generator is the basis for the monotropic FSH rise in older ovulatory women. Other possibilities include the dynamics of E2 secretion or changes in FSH-modulating peptides (i.e., inhibin) in these women.

Adult↗