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Biomedical subjects

J Yeh

Publications and source records attributed to J Yeh.

At least 91 records · Page 5Linked to original sources
PubMed1992

First trimester findings in pregnancies after in vitro fertilization.

We assessed the frequency of abnormal sonographic findings and their significance with respect to outcome in pregnancies resulting from in vitro fertilization (IVF). We retrospectively reviewed first trimester sonograms of 53 consecutive IVF patients who had a positive pregnancy test and first trimester ultrasonography at least 4 weeks after embryo transfer, and we correlated the sonographic findings with pregnancy outcome. For controls, we compared the frequency of sonographic abnormalities in these study patients to that in a group of patients who became pregnant after ovulation induction only. In the 53 IVF patients, the numbers of gestational sacs identified on the initial sonogram were as follows: 34 singletons, 11 twins, two triplets, one quadruplets and one quintuplets; no sac was seen in four patients. In 32 patients, the first sonogram was normal, with a visualized yolk sac, or heartbeat, or both. In 10 patients the gestational sac appeared abnormal but sac contents were normal. In seven patients an abnormality of sac contents was identified, including four with an embryo but no heartbeat and three anembryonic sacs. Overall, 40% of IVF patients had sonographic abnormalities, in comparison to 7% in the control group of patients (P less than 0.05, Fisher's exact test). Of the 32 patients with normal sonograms, 26 (81%) delivered at least one live infant. Of the 10 patients whose gestation sacs appeared abnormal, nine (90%) gave birth to live infants. Of the seven patients with abnormal sac contents, two (29%) delivered at least one live infant. We conclude that abnormal findings are frequently present on the initial sonogram of pregnant patients after IVF.(ABSTRACT TRUNCATED AT 250 WORDS)

Embryo Transfer↗
PubMed1991

Three-dimensional structures of the ligand-binding domain of the bacterial aspartate receptor with and without a ligand.

The three-dimensional structure of an active, disulfide cross-linked dimer of the ligand-binding domain of the Salmonella typhimurium aspartate receptor and that of an aspartate complex have been determined by x-ray crystallographic methods at 2.4 and 2.0 angstrom (A) resolution, respectively. A single subunit is a four-alpha-helix bundle with two long amino-terminal and carboxyl-terminal helices and two shorter helices that form a cylinder 20 A in diameter and more than 70 A long. The two subunits in the disulfide-bonded dimer are related by a crystallographic twofold axis in the apo structure, but by a noncrystallographic twofold axis in the aspartate complex structure. The latter structure reveals that the ligand binding site is located more than 60 A from the presumed membrane surface and is at the interface of the two subunits. Aspartate binds between two alpha helices from one subunit and one alpha helix from the other in a highly charged pocket formed by three arginines. The comparison of the apo and aspartate complex structures shows only small structural changes in the individual subunits, except for one loop region that is disordered, but the subunits appear to change orientation relative to each other. The structures of the two forms of this protein provide a step toward understanding the mechanisms of transmembrane signaling.

Amino Acid Sequence↗
PubMed1991

Synergistic effects of endothelin-1 (ET-1) and transforming growth factor alpha (TGF-alpha) or epidermal growth factor (EGF) on DNA replication and G1 to S phase transition.

The cooperative cell kinetic actions of ET-1 with TGF-alpha or EGF in normal rat kidney fibroblasts (NRK-49F) and KNRK cells (Kirsten MSV transformed) were analyzed by [3H]-thymidine incorporation assay and flow cytometry. A marked synergistic effect of TGF-alpha and ET-1 (or EGF and ET-1) on DNA synthesis and G1 to S transition was observed in NRK cells; 15-20% S for TGF-alpha and 12% S for ET-1 alone but 45-50% S in combination. There was no detectable effect on cell cycle kinetics by TGF-alpha (1 ng/ml) or EGF (1 ng/ml) plus ET-1 (1 ng/ml) in KNRK cells treated for 22 hours. Insulin, insulin-like growth factor I (IGF-I), fibroblast growth factor (FGF), platelet derived growth factor (PDGF), and transforming growth factor beta (TGF-beta) were also tested and found to have no significant synergistic effects on ET-1 actions. Our findings suggest that the combination of TGF-alpha (EGF) and ET-1 is an important part of an intricate network which coordinates progression of G1 to S phase in normal cells.

Animals↗
PubMed1991

mRNAs for insulin-like growth factor-II (IGF-II) and variant IGF-II are co-expressed in human fetal ovary and uterus.

Insulin-like growth factor-II (IGF-II) is postulated to have autocrine and/or paracrine functions in developing fetal tissues, but has never been reported in human fetal reproductive organs. The forms of IGF-II found in normal human serum include a 67 amino acid form and a variant form resulting from alternate splicing of the mRNA such that Ser-29 is replaced by four other amino acid residues. We studied the expression of mRNA encoding IGF-II in human fetal ovaries and uteruses of 10, 15, 19 and 22 weeks of gestation. By reverse transcription followed by polymerase chain reaction (PCR), we identified the co-expression of two mRNAs encoding IGF-II in all developmental stages of fetal ovaries and uteruses tested. One of the PCR amplified fragments was 9 nucleotides larger than the other. The PCR amplified ovarian and uterine DNA fragments were mapped by digestion with the restriction endonucleases AvaII and PvuII and both the IGF-II fragment and the larger IGF-II fragment produced the anticipated DNA patterns by gel electrophoresis. The PCR amplified DNA fragments were cloned and sequenced to confirm that the expressed mRNAs encoded IGF-II and variant IGF-II. We conclude that IGF-II and variant IGF-II mRNA co-expression occurs in the human fetal female genital tract and that the two forms of the growth factors may have physiologic roles in reproductive tract development.

Amino Acid Sequence↗
PubMed1991

Presence of messenger ribonucleic acid for epidermal growth factor (EGF) and EGF receptor demonstrable in monolayer cell cultures of myometria and leiomyomata.

There is a paucity of data concerning the factors involved in the growth of uterine leiomyomata. The expression of mRNAs encoding EGF and the EGF receptor in myometrial and leiomyoma cultures suggest that EGF may be involved in the autocrine/paracrine regulation of human uterine leiomyomata and myometrial growth.

Amino Acid Sequence↗
PubMed1991

Effect of fecal loading with/without peritonitis on the healing of a colonic anastomosis: an experimental study.

An experimental randomized prospective study was carried out in 64 dogs to evaluate the effect of intraluminal fecal matter at the anastomosis with/without peritonitis on the healing of a colonic anastomosis. The animals, none of whom had bowel preparation, were randomized in four groups: group I sigmoid resection and anastomosis, group II sigmoid resection and intraluminal fecal diversion from the anastomosis, group III induced fecal peritonitis, sigmoid resection and anastomosis and group IV induced fecal peritonitis, sigmoid resection and intraluminal fecal diversion from the anastomosis. Forty-eight hours before sacrifice at 5, 10 and 15 days, 10 microCi/kg C14 proline was given intravenously. Specimens were analyzed for hydroxyproline content, tissue counts and specific activity. The tissue counts and specific activity were analyzed by three-way analysis of variance. Overall, regardless of the groups, there was a statistically significant decrease in specific activity and tissue count from day 5 to day 15 and day 10 to day 15 at the anastomosis (p less than 0.05). When comparing groups II and IV to groups I and III, there was a significant increase in specific activity and tissue count at the anastomosis of group II and IV (p less than 0.05). This experimental study demonstrates that early anastomotic healing can occur even in presence of treated peritonitis as long as the fecal matter is diverted and prevented from coming in contact with the anastomotic site without disrupting the bowel continuity or function.

Anastomosis, Surgical↗
PubMed1990

Effect of haemodialysis on the pharmacokinetics of cetirizine.

The pharmacokinetics of Cetirizine, a histamine H1-receptor antagonist, were investigated in five renal failure patients undergoing chronic haemodialysis therapy. The patients received one 10 mg cetirizine dihydrochloride capsule 3 h before haemodialysis. Concentrations of cetirizine in serum and dialysate were determined by HPLC. The maximum serum cetirizine concentration and the time to reach that maximum were 285 micrograms.l-1 and 2.0 h, respectively. The terminal disposition half-life of cetirizine in these patients was 19.3 h. The haemodialysis clearance of cetirizine was 14.0 ml. min-1. Although this is approximately 33% of the apparent total body clearance of cetirizine in subjects with normal renal function, the fraction of the dose removed by dialysis was only 9.4%. Thus, since haemodialysis does not produce a clinically significantly alteration in cetirizine elimination, no supplemental dose should be necessary after dialysis.

Adult↗
PubMed1990

Neonatal aortic stenosis.

Aortic stenosis in the neonate has been associated in the past with a high operative mortality. As a result, in the current era of percutaneous balloon dilatation, the optimal mode of therapy remains controversial. An approach of stabilization with cardiopulmonary bypass, followed by relief of left ventricular outflow tract obstruction, was used at three institutions, and the results are presented. During the period 1983 to 1989, 40 neonates with isolated aortic stenosis and patent ductus arteriosus or coarctation of the aorta, or both, underwent operative therapy. Ages ranged from 1 to 30 days, median of 12 days, including 17 patients in the first week of life. There were 30 boys and 10 girls; weights ranged from 2.5 to 5.5 kg with a mean of 3.6 kg. Perioperative conditions included congestive heart failure in 38 and mitral regurgitation in 16; left ventricular-aortic gradients ranged from 15 to 130 mm Hg, with a mean of 67 mm Hg. There were 30 open valvotomies and 10 transventricular dilatations. The hospital survival rate was 87.5% (35/40) with no significant difference between the methods of valvotomy (9/10 in the transventricular dilatation group, 90%; 26/30 in the open valvotomy group, 87%). Although multiple methods of perfusion and valvotomy were used, the single unifying factor of cardiopulmonary bypass stabilization was present in all 40 patients. No significant difference in survival was noted between institutions, methods of cardiopulmonary bypass, cardiopulmonary bypass times, crossclamp times, or method of valvotomy. There have been five reoperations, with one late death in a patient requiring mitral valve replacement and an apical-aortic conduit. One sudden death occurred; autopsy revealed endocardial fibroelastosis. Results demonstrate that in the three institutions using the methods described, a high operative and late survival rate is possible. The results of this technique, against which percutaneous dilatation should be compared, are standard in the current era.

Aortic Valve↗
PubMed1989

Nicotine and cotinine inhibit rat testis androgen biosynthesis in vitro.

The effects of nicotine and cotinine, the major metabolite of nicotine, on testosterone production in rat testis were investigated. Rat Leydig cells were isolated and incubated with nicotine and cotinine. Nicotine produced a dose dependent increase in progesterone levels and a dose-dependent decrease in androstenedione and testosterone concentrations. Cotinine produced a dose-dependent increase in progesterone and androstenedione and a dose-dependent decrease in testosterone levels. The effects of nicotine and cotinine on rat testis mitochondrial cholesterol side chain cleavage enzyme and microsomal 3 beta-hydroxysteroid dehydrogenase-isomerase, 17 alpha-hydroxylase, 17,20-lyase and 17-ketosteroid reductase were examined. Nicotine competitively inhibited 17 alpha-hydroxylase (apparent Ki = 30 microM) and 17,20-lyase (apparent Ki = 18 microM). Cotinine competitively inhibited 17-ketosteroid reductase (apparent Ki = 46 microM). The addition of nicotine to preparations of rat testis microsomes yielded a Type II cytochrome P-450 binding spectrum. We conclude that nicotine and cotinine competitively inhibit multiple steps in testosterone biosynthesis.

Androgens↗
PubMed1989

Transforming growth factor-alpha and human cancer.

Human transforming growth factor-alpha TGF-alpha, a polypeptide growth factor which causes reversible transformation of normal cells, is composed of 50 amino acid residues, has a 30 to 40% amino acid homology to epidermal growth factor (EGF), and binds the EGF receptor. In human cancers, studies are beginning to show that TGF-alpha could serve as a tumor marker and as a marker for the malignant potential of a tumor. Thus far, the types of carcinomas with which abnormal TGF-alpha expression has been associated include liver, gastrointestinal, breast, skin, lung, brain and ovarian cancers. TGF-alpha may play a role in the processes involved with tumor initiation and tumor growth. In cell lines, TGF-alpha has been found to be associated with autocrine and paracrine types of cellular growth initiation and with increased levels of oncogene expression. In summary, the evidence concerning human TGF-alpha are that TGF-alpha could serve as a marker for human cancers and that an understanding of the basic actions of TGF-alpha could help to explain the self-sustaining nature of tumors.

Breast Neoplasms↗
PubMed1989

Twenty-four-hour urinary-free cortisol in premenopausal cigarette smokers and nonsmokers.

Cigarette smoking has been reported to produce acute increases in plasma ACTH and cortisol, but the effect of chronic smoking on integrated adrenal steroid production has not been studied. The effects of chronic smoking on 24-hour urinary-free cortisol, 11-deoxycortisol, DHEAS, and 17-keto-steroids were studied in 10 premenopausal smokers, and their results were compared with 15 premenopausal nonsmokers. The 24-hour excretion of urinary-free cortisol (85.0 +/- 40.8 nmol/d in smokers versus 81.7 +/- 49.7 nmol/d in nonsmokers), 11-deoxycortisol (259 +/- 170 nmol/d in smokers versus 222 +/- 147 nmol/d in nonsmokers), DHEAS (3,140 +/- 2,909 nmol/d in smokers versus 2,890 +/- 1,960 nmol/d in nonsmokers), and 17-ketosteroids (17.4 +/- 8.3 mumol/d in smokers versus 23.4 +/- 19.9 mumol/d in nonsmokers) were similar in smokers and nonsmokers (all P values not significant). We conclude that chronic smoking does not result in abnormal levels of 24-hour urinary-free cortisol.

17-Ketosteroids↗
PubMed1989

Pituitary function in isolated gonadotrophin deficiency.

Hypothalamic-pituitary function was assessed in 24 individuals with isolated gonadotrophin deficiency (IGD). Thirteen had normal olfaction (Group I) while 11 (Group II) had anosmia (Kallmann's syndrome). In response to a 10 micrograms intravenous (i.v.) bolus of GnRH, the minimal dose required to evoke a consistent gonadotrophin response in normal subjects, the patients responded with significant LH and FSH increases over baseline (P less than 0.01). In Group II patients, large doses (150 micrograms) of GnRH, which elicit maximal release of gonadotrophin in normal subjects did not increase gonadotrophin release beyond that produced by a 10 micrograms bolus. In response to two 10 micrograms GnRH doses, at times 0 and 120 min, the IGD patients responded with similar LH increases to both boluses (both P less than 0.01 compared to baseline). The maximal PRL responses to arginine infusion and to TRH in the male patients were similar to those of normal males. However, in the IGD females, the PRL response to TRH was less than in normal females. The TSH responses to TRH in IGD males and females were similar to each other and similar to normal. The IGD male GH response to arginine infusion was comparable to that in normal males. We conclude that (1) IGD patients appear to retain minimal endogenous GnRH secretion so that the IGD pituitary responds to a minimal dose of GnRH without priming; (2) IGD is a heterogeneous syndrome in which affected individuals with and without normal olfaction represent parts of the spectrum of the same disease; and (3) except for the PRL response in females, the PRL, TSH and GH responses demonstrate that the IGD pituitaries are largely intact.

Adolescent↗
PubMed1988

Cesarean section-related maternal mortality in Massachusetts, 1954-1985.

We analyzed the data of the Maternal Mortality Committee of the Massachusetts Medical Society to investigate cesarean section-associated maternal deaths. Between 1954-1985, the number of cesarean section-related deaths per 100,000 live births did not significantly change despite a quadrupling of the cesarean section rate. Between 1976-1984, there were 649,375 births and 121,217 cesarean sections in the state. Seven deaths were directly related to cesarean section, a rate of 5.8 per 100,000 cesarean sections. In contrast, the rate for vaginal deliveries was 10.8 per 100,000 vaginal deliveries. We conclude that the risk of maternal death from cesarean section is low.

Cesarean Section↗