Biomedical subjects

M C Snabes

Publications and source records attributed to M C Snabes.

At least 19 recordsLinked to original sources

PubMed2000

Clinical use of nafarelin in the treatment of leiomyomas. A review of the literature.

OBJECTIVE: To review the efficacy and safety of nafarelin in the treatment of leiomyomas. STUDY DESIGN: A literature review of published clinical trials was conducted. Six studies, including a total of 602 patients with leiomyomas, were reviewed. Patients received intranasal nafarelin, 50-400 micrograms twice daily for three to six months. Vaginal bleeding patterns, leiomyoma and uterine size, surgical conditions and adverse effects were assessed. RESULTS: Nafarelin consistently suppressed estrogen production, reduced leiomyoma and uterine size, and controlled menorrhagia. The significant reduction in uterine bleeding and amenorrhea resulting from administration of nafarelin was associated with a rise in mean hemoglobin concentrations. In addition, nafarelin improved hematologic parameters in women with and without anemia. Nafarelin was well tolerated, although hot flushes were the most commonly reported adverse events. Measured bone mineral density decreased significantly during treatment, although by six to nine months post-treatment, it increased to values not significantly different from baseline. The adverse effects of nafarelin were generally reversible after treatment withdrawal. CONCLUSION: Nafarelin treatment of women with symptomatic leiomyomas effectively decreases uterine bleeding; improves hematologic parameters; manages symptoms of menometrorrhagia, dysmenorrhea and pelvic discomfort; reduces uterine and myoma size; and is well tolerated. Reduction in bone mineral density occurs, but levels return to, or near, baseline levels within six months after treatment.

Abdominal Pain↗

PubMed1998

Ascorbic acid supplement use and the prevalence of gallbladder disease. Heart & Estrogen-Progestin Replacement Study (HERS) Research Group.

To investigate the relation of ascorbic acid supplement use to gallbladder disease and cholecystectomy, we conducted a cross-sectional analysis of baseline from 2744 postmenopausal women, aged 44-79 years, enrolled in the Heart & Estrogen-progestin Replacement Study (HERS), a secondary coronary heart disease prevention trial. A total of 629 HERS participants (23%) reported a history of gallbladder disease. Of these, 508 (19%) also reported a history of cholecystectomy. In bivariate models, ascorbic acid supplement use was associated with a decreased prevalence of gallbladder disease [odds ratio (OR)=0.74; 95% confidence interval (CI), 0.57, 0.96] and a trend toward a decreased prevalence of cholecystectomy (OR=0.77; 95% CI, 0.58, 1.02). Because we detected significant interactions between ascorbic acid supplement use and alcohol consumption, multivariate analyses were performed stratified by drinking status. After adjustment for potential confounding variables, use of ascorbic acid supplements among drinkers was associated with a decreased prevalence of gallbladder disease (adjusted OR=0.50; 95% CI, 0.31, 0.81) and cholecystectomy (adjusted OR=0.38; 95% CI, 0.21, 0.67). Use of ascorbic acid supplements among non-drinkers was not significantly associated with either prevalence of gallbladder disease or cholecystectomy. Further study is necessary to confirm our findings and, specifically, to examine the combined effects of ascorbic acid and alcohol on cholesterol metabolism.

Adult↗

PubMed1997

Physiologic estradiol replacement therapy and cardiac structure and function in normal postmenopausal women: a randomized, double-blind, placebo-controlled, crossover trial.

OBJECTIVE: To assess the effect of estradiol (E2) replacement therapy on cardiac structure and function in healthy postmenopausal women. METHODS: We conducted a randomized, double-blind, placebo-controlled, crossover study of 31 healthy postmenopausal female volunteer study subjects (55-65 years) using 12 weeks of micronized E2 replacement therapy (2 mg/day). Echocardiography and Doppler techniques were used to assess the cardiac effects of E2 at rest and during graded bicycle ergometry. RESULTS: Crossover analysis demonstrated no carryover effects of estrogen treatment (which increased serum E2 15-fold to 37.6 pmol/L) on the cardiac characteristics measured. Estradiol treatment did not affect measurements of systolic function, diastolic function, left ventricular mass, or pulmonary artery pressure at rest or during bicycle ergometry. Left ventricular end-diastolic volume at rest was slightly higher with E2 treatment (P = .03). However, this change was not reflected by changes in stroke volume, ejection fraction, or cardiac output. CONCLUSIONS: Estrogen replacement therapy, which results in physiologic serum concentrations, does not affect cardiac structure or function in normal postmenopausal women after 12 weeks of treatment.

Aged↗

PubMed1997

Effect of postmenopausal estrogen replacement on circulating androgens.

OBJECTIVE: To determine the effect of estrogen replacement therapy (ERT) on serum androgen levels in postmenopausal women. METHODS: We measured serum dehydroepiandrosterone (DHEA), DHEA-sulfate, testosterone, estradiol (E2), LH, FSH, and sex hormone binding globulin in 8:00 AM fasting serum samples from a previous randomized, blinded, placebo-controlled crossover study in which 28 postmenopausal women (27 naturally menopausal) were given 2 mg/day of oral micronized estradiol. The treatment arms were 12 weeks with a 6-week washout. RESULTS: Estrogen replacement therapy raised mean (+/- standard error of the mean [SEM]) serum E2 from 8.7 +/- 1.0 to 117 +/- 18.7 pg/mL (P < .001 from baseline). Concurrently, mean (+/- SEM) DHEA-sulfate fell from 67.3 +/- 9.6 to 52.1 +/- 6.4 micrograms/dL (P < .001), and mean (+/- SEM) testosterone fell from 16.1 +/- 2.4 to 9.4 +/- 1.4 ng/dL (P = .006). Both FSH and LH declined significantly. Sex hormone binding globulin increased by 160% with ERT (P < .001). CONCLUSION: Menopausal ERT decreases serum androgen levels, decreasing DHEA-sulfate and testosterone by 23% and 42%, respectively. Whereas the decline in testosterone is likely due to decreased LH-driven ovarian stromal steroidogenesis, the declining levels of DHEA-sulfate also may imply a direct adrenal effect of estrogen. Bioavailable testosterone likely is reduced even more profoundly because sex hormone binding globulin is increased 160% by estrogen. Thus, menopausal ERT may induce relative ovarian and adrenal androgen deficiency, creating a rationale for concurrent physiologic androgen replacement.

Aged↗

PubMed1996

In normal postmenopausal women physiologic estrogen replacement therapy fails to improve exercise tolerance: a randomized, double-blind, placebo-controlled, crossover trial.

OBJECTIVE: Our purpose was to test whether estrogen replacement therapy could increase exercise tolerance in postmenopausal women. STUDY DESIGN: A randomized, double-blind, placebo-controlled, crossover study in 31 healthy postmenopausal women who received 12 weeks of physiologic estrogen replacement therapy (micronized estradiol, 2 mg/day) and were evaluated with modified Balke exercise treadmill tests. RESULTS: Serum estradiol levels increased significantly during replacement therapy in this cohort of female volunteers with a mean age of 59 years, and resting heart rate was lower in women receiving estrogen replacement (p < 0.05). However, neither the heart rate nor the blood pressure responses to exercise was different, nor was the total exercise time, rate of oxygen uptake, or maximal oxygen uptake increased after estradiol treatment. Similarly, ventilatory parameters were unaffected by estradiol. The slope of the respiratory exchange ratio was slightly but significantly different (p < 0.05) while volunteers received estrogen replacement therapy. CONCLUSION: Estrogen replacement therapy, which achieves serum estradiol concentrations in the physiologic range for 12 weeks, fails to increase exercise tolerance or improve cardiovascular response to exercise in postmenopausal women.

Cross-Over Studies↗

PubMed1995

Single-cell analysis of the RhD blood type for use in preimplantation diagnosis in the prevention of severe hemolytic disease of the newborn.

OBJECTIVE: Our purpose was to develop a molecular assay to determine the fetal RhD blood type on single diploid cells, including blastomeres. STUDY DESIGN: Polymerase chain reaction amplification of a 99 bp deoxyribonucleic acid fragment of the RhD gene or a 113 bp fragment from the RhCE gene was performed from 20 venous blood samples and 20 amniotic fluid samples and from 60 single-cultured lymphoblasts and 12 media blanks mixed in a blinded fashion. This reaction was similarly tested after whole-genome amplification on 10 lymphoblasts and seven human blastomeres. RESULTS: Deoxyribonucleic acid amplification was successful and correct from all genomic deoxyribonucleic acid samples. Ninety-seven percent of single cells amplified; correct diagnosis was made in 96%. Five blastomeres successfully amplified. No media blanks produced amplified, contaminating deoxyribonucleic acid. CONCLUSIONS: The RhD blood type can be determined reliably from single cells and can be used for preimplantation genetic diagnosis for the prevention of rhesus hemolytic disease.

Amniotic Fluid↗

PubMed1994

Preimplantation single-cell analysis of multiple genetic loci by whole-genome amplification.

Due to the limited amount of DNA in a single diploid cell, preimplantation genetic diagnosis has relied on single- or dual-locus analyses in biopsied blastomers. We have applied single-cell whole-genome preamplification to PCR-based analysis of multiple disease loci from the same diploid cell. This method allows diagnosis of multiple disease genes, analysis of multiple exons/introns within a gene, or corroborative embryo-sex assignment and specific mutation detection at sex-linked loci. A blinded study of six genetic loci was performed with whole-genome preamplification followed by nested PCR. Amplification was observed in 103 of 105 assays (98%) and a correct diagnosis was made in 98%. All human blastomeres were correctly diagnosed (100%) at loci where the genotype could be confirmed, attesting to the reliability of the technique. Preamplification has now been applied successfully to the analysis of the two major mutations responsible for Tay-Sachs disease and of a common restriction polymorphism in the gene responsible for hemophilia A. The fidelity and length of product derived from this preamplification step make it an appealing technique for preimplantation genetic diagnoses requiring analyses at more than one locus.

Base Sequence↗

PubMed1994

Molecular analysis of human platelet antigen system 1 antigen on single cells can be applied to preimplantation genetic diagnosis for prevention of alloimmune thrombocytopenia.

OBJECTIVE: Our purpose was to develop a molecular assay to determine the human platelet antigen system 1 status on single nucleated cells, including human blastomeres. STUDY DESIGN: Eighty single cultured lymphoblasts of known human platelet antigen system 1 genotype and 24 media blanks were mixed in blinded fashion. Amplification of a 246 bp deoxyribonucleic acid fragment and subsequent Nci I restriction digestion were performed to distinguish human platelet antigen system 1a from 1b alleles. Specificity and sensitivity of the technique were determined. Eight blastomeres were also tested. RESULTS: Deoxyribonucleic acid amplification at the human platelet antigen system 1 locus was successful in 95% of the reactions. No media blanks showed amplified deoxyribonucleic acid. The diagnosis was correct in all homozygous human platelet antigen system 1a or 1b cells; three of 23 heterozygous cells amplified but failed to digest with Nci I. Overall specificity was 95%. All blastomeres successfully amplified. CONCLUSIONS: The human platelet antigen system 1 status determination is reliable from a single cell and can be used for preimplantation genetic diagnosis for the prevention of alloimmune thrombocytopenia.

Antigens, Human Platelet↗

PubMed1994

Preimplantation single cell analyses of dystrophin gene deletions using whole genome amplification.

Primer extension preamplification (PEP) increases the scope and capacity of single cell genetic diagnosis by generating sufficient template to perform multiple subsequent DNA analyses using the polymerase chain reaction. We report the simultaneous analysis of single cells at five commonly deleted dystrophin exons and at the ZFX/ZFY loci. Ninety three percent of PEP reactions with single amniocytes, chorionic villus cells and blastomeres were successful, and a blinded analysis of single lymphoblasts from affected males resulted in 93% diagnostic accuracy, demonstrating its applicability in preimplantation prevention of Duchenne muscular dystrophy. Transfer of unaffected male embryos and improved diagnostic reliability are achieved with the ability to perform replicate multilocus analyses from the same blastomere.

Base Sequence↗

PubMed1994

Prevalence of HIV seropositivity among inner-city adolescents in 1988 and 1992.

The purpose of this study was to document the change in prevalence of human immunodeficiency virus (HIV) infection among sexually active minority teens at a primary and reproductive teen health clinic. Both new and current patients were sampled in a seroprevalence study in 1988 and again in 1992. None of the 1200 adolescents sampled were seropositive for HIV in 1988. Nine of the 1085 adolescents sampled were seropositive in 1992. Five of these 9 teens reported heterosexual contact only as a potential risk factor. Six of these 9 teens were not in school. These results suggest that HIV infection is increasing among Texas urban teens. Because current education programs do not appear to be preventing viral spread, new, focused intervention must be initiated for teenagers. In particular, an effective acquired immunodeficiency syndrome prevention program for out-of-school youth is needed urgently.

Adolescent↗

PubMed1993

Cryopreserved mouse embryos can successfully survive biopsy and refreezing.

OBJECTIVE: We examined whether cryopreserved mouse eight-cell embryos could be thawed, biopsied, refrozen, thawed, and grown in vitro and in vivo in two sets of experiments. METHOD: In the in vitro studies, the blastulation rate of cryopreserved embryos which had been thawed-->biopsied-->refrozen-->thawed-->grown 48 hr in vitro were compared with that of sham-operated (zona dissected) and untreated control embryos (twice frozen only). For the in vivo studies, five control embryos were transferred to one horn and five experimental embryos were transferred to the contralateral horn of day 3 pseudopregnant recipient female mice. Recipient mice were sacrificed on day 18. RESULTS: The day 2 blastulation rate was the same for the control, sham-operated, and biopsied embryos when examined in vitro. In the first set of in vivo studies, 42.7% of control and 39.7% of sham-operated embryos that had been transferred implanted, and most embryos progressed to day 18. In the second set, 45.6% (57/125) and 39.7% (49/125), respectively, of the transferred embryos progressed to day 18 fetuses. There were no significant differences in the rate of fetal development in the different groups. CONCLUSIONS: These studies demonstrate that cryopreserved mouse eight-cell embryos can successfully undergo thawing, biopsy, and refreezing. The results suggest that under certain conditions, it may be possible to utilize cryopreservation in strategies involving human genetic diagnosis in the preimplantation period.

Animals↗

PubMed1993

The effects of a long-acting progestin on the hypothalamic-pituitary-ovarian axis in women with normal menstrual cycles.

This study was performed to determine how a long-acting, slow-release preparation of norethindrone (NET) affects the hypothalamic-pituitary-ovarian axis of normal ovulatory women. Ten women were studied during the luteal phase of their menstrual cycle, and again at six and twelve weeks following intramuscular administration of 100 mg NET microencapsulated in poly-D,L-lactide-co-glycolide. Serial LH samples, serum E, P, and NET were followed by a GnRH stimulation test. Compared to luteal phase values, six and twelve weeks of treatment with NET inhibited serum E2 and P while mean serum LH remained unchanged and mean serum FSH increased significantly (p < 0.05). LH pulse frequency after NET treatment was twice the rate (p < 0.01) as that of the luteal phase, whereas LH pulse amplitude was decreased significantly (p < 0.05). Finally, although there was no significant change in pituitary LH secretion in response to GnRH, NET treatment augmented FSH responsiveness to GnRH at the times studied. Preserved pituitary responsiveness to GnRH in NET-treated patients suggests that inhibited ovarian function results in an increase in GnRH pulse frequency but not GnRH pulse amplitude. Since the progestational milieu is maintained in these patients by NET treatment, the decrease in serum E2 may be responsible for the increase in GnRH pulse frequency. The presence of a critical level of E2 may be necessary for progestins to affect the hypothalamic GnRH pulse generator.

Adult↗

PubMed1993

A severe puerperal group A streptococcal infection causing a toxic shock-like syndrome.

Toxic shock syndrome (TSS) is classically associated with vaginal recovery of Staphylococcus aureus during menses. In this case a patient presented with fever, rash, abdominal pain and signs of shock, 6 days postpartum. Blood cultures were negative but endometrial cultures were positive for Group A beta-hemolytic streptococcus. This case presents a toxic shock-like syndrome due to streptococcus, (toxic streptococcus syndrome) and points out the importance of culturing these patients for organisms other than Staphylococcus aureus.

Adolescent↗

PubMed1993

GnRH agonist exposure during the first trimester of pregnancy.

OBJECTIVE: To evaluate pregnancy outcome in infertility patients with unrecognized exposure to a GnRH agonist in the first trimester. METHODS: Five women were given GnRH agonist before controlled ovarian hyperstimulation for in vitro fertilization cycles. The medication was administered in a dose of 0.5 mg/day, with drug exposure beginning on cycle day 21. The duration of exposure in all patients was 14-21 days. Thus, all five women received the medication at 3-6 weeks' estimated gestational age by menstrual dating. Pregnancy tests were not performed before the first injection of the GnRH agonist. RESULTS: Three of the five pregnancies progressed to term without complication, and normal healthy infants were delivered. Missed abortion occurred in one pregnancy, and another ended in induced abortion at 13 weeks because of trisomy 18. CONCLUSIONS: This experience suggests that despite manipulation of the hypothalamic-pituitary-ovarian axis by administration of GnRH agonist in the first trimester of pregnancy, normal pregnancies can result. Pregnancies in these patients should not be terminated because of drug exposure alone.

Abortion, Missed↗

PubMed1992

A randomized, double-blind, placebo-controlled comparison of the impact of low-dose and triphasic oral contraceptives on follicular development.

OBJECTIVE: This investigation tests the hypothesis that triphasic oral contraceptives are associated with the development of large, persistent ovarian cysts. STUDY DESIGN: Weekly vaginal ultrasonography was used in a randomized, double-blind, placebo-controlled, parallel-group, single-center study that compared the incidence, risk, size, and time to resolution of ovarian follicles in healthy women who took Estrostep or Loestrin oral contraceptives (manufactured by Parke-Davis) or a placebo during three consecutive menstrual cycles. RESULTS: Sixty-three percent of placebo-treated subjects developed follicles greater than 18 mm, compared with 39% and 23% in the Estrostep and Loestrin groups. The risks for each group of developing a large follicle during a single cycle were not different. No dominant follicle persisted for greater than 2 weeks for any subject. CONCLUSION: These results demonstrate that follicular development continues during treatment with oral contraceptives. In addition, the findings fail to support the hypothesis that triphasic oral contraceptives result in persistent ovarian cysts.

Adult↗

PubMed1992

Hysterosalpingographic diagnosis of Crohn's disease. A case report.

A woman presented with abdominal pain, weight loss and a pelvic mass. At the time of laparotomy she had a lower abdominal abscess from perforation of the ileum. Two years later she returned with a tender uterus and purulent cervical discharge. A hysterosalpingogram demonstrated an uteroileal fistula secondary to Crohn's disease, and the patient underwent a total abdominal hysterectomy and bilateral salpingo-oophorectomy.

Adult↗

PubMed1991

Laparoscopic tubal sterilization under local anesthesia in women with cyanotic heart disease.

Laparoscopic tubal sterilization under local anesthesia with intravenous sedation has been shown to be a safe procedure. However, the use of laparoscopy in patients with cyanotic cardiovascular disease is controversial and is generally contraindicated. Five women were referred with uncorrectable cyanotic heart disease and pulmonary hypertension. The mean preoperative arterial oxygen pressure was 56.2 +/- 5 mmHg (N = 5). After cardiology and cardiovascular anesthesia consultation and clearance, the patients underwent laparoscopic sterilization with Silastic rings under local anesthesia using direct trocar entry. Continuous hemodynamic monitoring and pulse oximetry were employed. The patients were kept in the intensive care unit or the hospital for 24 hours for monitoring, and all did well. This hospital for 24 hours for monitoring, and all did well. This small retrospective series demonstrates that laparoscopic sterilization under local anesthesia is a sterilization technique that may be suitable and safe for such patients when appropriate monitoring is performed. Tubal sterilization may be the contraceptive method of choice in women with heart disease when pregnancy is contraindicated.

Adult↗

PubMed1989

Characterization of prostaglandin E2 binding to uterine membranes from baboon, rabbit and tree shrew (Tupaia belangeri).

Membrane preparations (100,000 g pellet) of rabbit, baboon and tree shrew (Tupaia belangeri) uteri were studied for binding of [3H]prostaglandin E2 ([3H]PGE2). Unbound [3H]PGE2 was separated by filtration through Whatman GF/F filters. Non-specific binding was determined by the amount of radioactivity associated with the filters in the presence of a 100-fold excess of radioinert PGE2. PGE2 bound to membranes could be displaced by some other prostaglandin (PG) molecules: PGE1, 16,16-dimethyl-PGE2, PGA1 and PGF2 alpha, but not by 6-keto-PGF1 alpha, PGD2 or arachidonic acid. No PGE2 binding was detected using either membrane ghosts from red blood cells or liposomes. Apparent equilibrium of the binding was reached by 60 min. There was no difference in dissociation constant (Kd) values between rabbits of different reproductive stages (mean range +/- S.E.M. was from 4.6 +/- 0.3 to 5.5 +/- 1.0 nM), but pregnant baboons showed a significantly lower value (3.3 +/- 0.4 nM) than did cyclic animals (12.0 +/- 2.0 nM). Binding capacity (Bmax) values, in contrast, were different only between oestrous rabbits and other reproductive stages. The small amounts of Tupaia tissue only permitted estimates of the Kd and Bmax values to be made; these were 3.8 nM and 499 fmol/mg protein for oestrous animals and 5.4 nM and 674 fmol/mg protein for animals on day 7 of pregnancy, assuming only one class of sites. The present results demonstrate the presence of specific binding sites for PGE2 in uteri from several species.

Animals↗