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Biomedical subjects

J Thornton

Publications and source records attributed to J Thornton.

At least 73 records · Page 4Linked to original sources
PubMed1998

Synergistic effects of feeding and dexamethasone on serum leptin levels.

The objectives of this study were to determine the time course of the stimulatory effect of dexamethasone on serum leptin and whether it depends on food intake. Dexamethasone (4mg) was administered I.V. over 1 minute to healthy human volunteers (n=8) under fasting and feeding conditions (2000 kcal given at three meals over 7 hours). At 10 hours, serum leptin levels were increased only in the fed subjects (delta leptin 10.6+/-1.6 vs -2.4+/-1.9 ng/ml, p=0.01, n=8). To assess the interactive effect of food and dexamethasone on serum leptin, a subgroup (n=4) was studied under 4 conditions: 1) dexamethasone/fast; 2) dexamethasone/food; 3) saline/fast; 4) saline/food. Serum leptin declined from baseline under the fasting conditions, with or without dexamethasone. Feeding prevented the drop in serum leptin. In the dexamethasone/food condition, leptin levels rose from baseline after 7 hours and doubled after 10 hours (p<0.05). The rise in serum leptin was significantly greater in the food/dexamethasone condition compared to all other conditions (p<0.05). In summary, dexamethasone has no independent effect on serum leptin in the absence of food intake. Rather, dexamethasone appears to potentiate the food-induced increase in serum leptin. This synergism may be mediated by insulin and/or other factors associated with food ingestion.

Adult↗
PubMed1997

Body fat and water changes during pregnancy in women with different body weight and weight gain.

OBJECTIVE: To determine the fat deposited during pregnancy in women gaining according to recommendations of the Institute of Medicine and the relationship of weight gain to fat gain in women of different starting weights (classified by their body mass index). METHODS: A cohort study of healthy, nonsmoking women, 18-36 years of age, identified during prenatal visits at three hospital clinics and one birthing center in New York City. From a pool of 432 eligible volunteers who signed a consent form, body composition measurements were performed on 200 women at weeks 14 (+/-2) and 37+ of pregnancy, and bone mineral mass was measured at 2-4 weeks postpartum. Body fat was estimated with a model that used total body water, weight, and density and bone mineral mass. RESULTS: In women gaining as recommended by the Institute of Medicine, fat gains during pregnancy for women underweight, normal weight, overweight, or obese before pregnancy were 6.0 +/- 2.6 kg, 3.8 +/- 3.4 kg, 3.5 +/- 4.1 kg, and -0.6 +/- 4.6 kg, respectively. Higher weight gain increased fat gain. Body water gain was not different among the four prepregnancy weight groups. CONCLUSION: Recommended weight gain should not cause obesity in any weight group. Underweight women will normalize their body composition if they gain as recommended, whereas obese women will have little or no change in body fat. A majority of women do not gain as recommended during pregnancy.

Adipose Tissue↗
PubMed1997

Genetic factors in the aetiology of gastroschisis: a case report.

Isolated gastroschisis in two children of unrelated mothers but with the same father is described. There was no evidence of consanguinity, abnormal karyotype or a specific teratogen in either case. Genetic factors may be involved in the aetiology of some cases of gastroschisis.

Abdominal Muscles↗
PubMed1997

Combination oral antioxidant supplementation reduces blood pressure.

1. Hypertension affects 30% of adults and low intakes of antioxidants have been associated with increased risk of hypertension and cardiovascular disease. To investigate the effect of short-term high-dose antioxidant supplementation on blood pressure in hypertensive and normotensive outpatients, we undertook a randomized, double-blind, crossover design placebo-controlled study. 2. Forty subjects were recruited from medical outpatient clinics, of whom 38 completed the study. Twenty-one were attending for treatment of hypertension and 17 were normotensive, attending for minor gastrointestinal complaints. Subjects were randomly assigned to receive either 8 weeks placebo followed by 2 weeks washout then 8 weeks antioxidants or vice versa. The combination of antioxidants consisted of 200 mg of zinc sulphate, 500 mg of ascorbic acid, 600 mg of alpha-tocopherol (sodium succinate salt) and 30 mg of beta-carotene daily. 3. Systolic blood pressure fell at the end of the antioxidant phase compared with the placebo phase both in subjects receiving anti-hypertensive therapy (P < 0.01) and those who were normotensive (P = 0.067). Circulating levels of beta-carotene and alpha-tocopherol increased in all subjects during supplementation (P < 0.01) and urine nitrite increased in hypertensive patients (P < 0.05). 4. Short-term oral high-dose combination antioxidant therapy reduces blood pressure, possibly via increased availability of nitric oxide. This study may have implications for the innovative use of antioxidants as an adjunct to anti-hypertensive therapy.

Administration, Oral↗
PubMed1997

Randomised trial comparing a policy of early with selective amniotomy in uncomplicated labour at term.

OBJECTIVE: To compare two management policies: rupture of the fetal membranes when women are in normal labour or leave them intact as long as feasible. SETTING: The labour ward of a city university hospital. DESIGN: Automated randomised clinical trial. PARTICIPANTS: 1540 women in uncomplicated term labour. Data on labour duration, blood loss, oxytocin use and fetal condition were collected from 1132 women. Some data from nulliparous women has been presented earlier by the UK Amniotomy Group. MAIN OUTCOME MEASURES: Duration of labour, Apgar score, fetal morbidity and maternal morbidity including perineal injury, mode of delivery, epidural rates and the total number of vaginal examinations in the first stage of labour after amniotomy. INTERVENTIONS: Amniotomy at the next vaginal examination or amniotomy only if indicated. The median cervical dilatation at membrane rupture was 2 cm greater in the first group. RESULTS: A policy of routine amniotomy in labour had no measurable advantage over selective amniotomy for parous women (difference = 4 min) but shortened labour in nulliparous women by 1 h (Mann-Whitney U test: P < 0.05). There was a suggestion of a higher caesarean section rate (OR 1.9; 95% CI 0.9-3.5), and there were more vaginal examinations after membrane rupture in the group allocated routine amniotomy. There were no measurable differences in oxytocin use, fetal condition at birth, retained placenta rates, blood loss, pain or analgesia requirements. CONCLUSION: Routine amniotomy may shorten the first labour but not subsequent ones. There is a suggestion that routine surgical interference may be harmful by increasing the risk of caesarean section, and this agrees with data from other trials (common odds ratio 1.2; 95% CI 0.92-1.6).

Adult↗
PubMed1997

A basic helix-loop-helix-leucine zipper transcription complex in yeast functions in a signaling pathway from mitochondria to the nucleus.

The expression of some nuclear genes in Saccharomyces cerevisiae, such as the CIT2 gene, which encodes a glyoxylate cycle isoform of citrate synthase, is responsive to the functional state of mitochondria. Previous studies identified a basic helix-loop-helix-leucine zipper (bHLH/Zip) transcription factor encoded by the RTG1 gene that is required for both basal expression of the CIT2 gene and its increased expression in respiratory-deficient cells. Here, we describe the cloning and characterization of RTG3, a gene encoding a 54-kDa bHLH/Zip protein that is also required for CIT2 expression. Rtg3p binds together with Rtg1p to two identical sites oriented as inverted repeats 28 bp apart in a regulatory upstream activation sequence element (UASr) in the CIT2 promoter. The core binding site for the Rtg1p-Rtg3p heterodimer is 5'-GGTCAC-3', which differs from the canonical E-box site, CANNTG, to which most other bHLH proteins bind. We demonstrate that both of the Rtg1p-Rtg3p binding sites in the UAS(r) element are required in vivo and act synergistically for CIT2 expression. The basic region of Rtg3p conforms well to the basic region of most bHLH proteins, whereas the basic region of Rtg1p does not. These findings suggest that the Rtg1p-Rtg3p complex interacts in a novel way with its DNA target sites.

Amino Acid Sequence↗
PubMed1996

Application of bioimpedance analysis for estimating body composition in prepubertal children infected with human immunodeficiency virus type 1.

The purpose of this study was to evaluate the performance of bioimpedance analysis (BIA) in the prediction of total body water and fat free mass with the use of standard equations in assessing 20 prepubertal children infected with human immunodeficiency virus (HIV). Total body water was measured by means of deuterium oxide dilution, fat free mass by means of total body dual X-ray absorptiometry, and BIA with a bioelectrical impedance analyzer. The use of standard prediction equations resulted in substantial error. Regression equations using height and BIA resistance for estimating total body water and fat free mass were developed and appear to improve accuracy for prediction. This study suggests that total body water and fat free mass can be estimated in children with HIV by means of BIA equations specifically developed for use with this group of children.

Adipose Tissue↗
PubMed1996

Central venous line sepsis in the intensive care unit. A study comparing antibiotic coated catheters with plain catheters.

A randomized controlled clinical trial was undertaken to evaluate the efficacy of antibiotic bonded lines in the reduction of central venous catheter infection. One hundred and seventy-six plain and bonded catheters were inserted into one hundred and ten patients in an intensive care unit, many of whom were admitted with evidence of sepsis. The catheters used in the study group, which had been pre-treated by the manufacturers with the cationic surfactant tridodecylmethylammonium chloride, were bonded with vancomycin 1 g made up in 10 ml of water immediately prior to insertion. The catheters used in the control group were neither pre-treated nor bonded with vancomycin. Eighty percent of control group catheters were infected compared with 62% of study catheters (p = 0.01). The most common organism isolated was coagulase negative staphylococcus. We conclude that antibiotic bonding can reduce central venous catheter infection even in a patient population with a high incidence of sepsis.

Anti-Bacterial Agents↗
PubMed1996

The effect of routine early amniotomy on spontaneous labor: a meta-analysis.

OBJECTIVE: To obtain estimates of the effects of amniotomy on the risk of cesarean delivery and on other indicators of maternal and neonatal morbidity (Apgar score less than 7 at 5 minutes, admission to neonatal intensive care unit [NICU]). DATA SOURCES: Published studies were identified through manual and computerized searches using Medline and the Cochrane Collaboration Pregnancy and Childbirth Database. METHODS OF STUDY SELECTION: Our search identified ten trials, all published in peer-reviewed journals. Trials were assigned a methodological quality score based on a standardized rating system. Three trials were excluded from the analysis for methodological limitations. TABULATION, INTEGRATION, AND RESULTS: Data were abstracted by two trained reviewers. Typical odds ratios (OR) were calculated. Amniotomy was associated with a reduction in labor duration varying from 0.8-2.3 hours. There was a nonstatistically significant increase in the risk of cesarean delivery; OR 1.2, 95% confidence interval (CI) 0.9-1.6. The risk of a 5-minute Apgar score less than 7 was reduced in association with early amniotomy (OR 0.5, 95% CI 0.3-0.9). Groups were similar with respect to other indicators of neonatal status (arterial cord pH, NICU admissions). CONCLUSION: Routine early amniotomy is associated with both benefits and risks. Benefits include a reduction in labor duration and a possible reduction in abnormal 5-minute Apgar scores. This meta-analysis provides no support for the hypothesis that routine early amniotomy reduces the risk of cesarean delivery. An association between early amniotomy and cesarean delivery for fetal distress was noted in one large trial, suggesting that amniotomy should be reserved for patients with abnormal labor progress.

Amnion↗
PubMed1995

An acetylglucomannan esterase of Aspergillus oryzae; purification, characterization and role in the hydrolysis of O-acetyl-galactoglucomannan.

An acetyl glucomannan esterase (AGME) was purified to electrophoretic homogeneity from the culture supernatant of Aspergillus oryzae. This new enzyme had a molecular mass of 36 kDa and an isoelectric point of 4.6. It was most active in the pH range 5.0-5.5 and was stable for 24 h at 40 degrees C at pH 5.0-6.0. The purified esterase liberated acetic acid from O-acetyl-galactoglucomannan, O-acetyl-4-O- methylglucuronoxylan and alpha-naphtyl acetate. The specific activity was 10-times higher for acetylated mannan than for acetylated xylan. The enzyme was able to act on polymeric substrate but activity was clearly enhanced by addition of mannanase from Trichoderma reesei and alpha-galactosidase from guar seeds. Presence of mannanase also increased the liberation of acetic acid in long-term hydrolysis (24 h), while the addition of alpha-galactosidase had no effect. No significant synergism between these two glycanases and the previously characterized esterase of A. oryzae (FE), which is also able to deacetylate galactoglucomannan, was observed. Even though the AGME had 8-times higher specific galactomannan deacetylating activity than the FE, the maximum amount of acetic acid liberated from the polymeric galactoglucomannan by AGME was only 80% of that of FE. Both esterases clearly enhanced the action of mannanase and alpha-galactosidase in the degradation of O-acetyl-galactoglucomannan isolated from Norway spruce.

Aspergillus oryzae↗
PubMed1995

Internal thoracic artery grafts: 20-year clinical follow-up.

OBJECTIVES: This study compared the long-term clinical results of coronary artery bypass surgery in patients with internal thoracic artery grafts with those in patients with vein grafts only. BACKGROUND: Aortocoronary artery bypass surgery has been performed for > 25 years, primarily utilizing the saphenous vein and internal thoracic artery as conduits. Although the internal thoracic artery has been shown to confer a clinical advantage, it is not known for how many years this benefit will continue. METHODS: All consecutive patients undergoing initial coronary artery bypass surgery between 1970 and 1973 were followed for up to 20 years. Clinical evaluation included survival, late myocardial infarction, need for reoperation and recurrence of angina. Patients were analyzed in three groups: vein grafts only (214 patients); a single internal thoracic artery graft with or without associated vein grafts (490 patients); and bilateral internal thoracic artery grafts (39 patients). Use of the operating microscope was also analyzed with regard to effect on survival. RESULTS: The internal thoracic artery graft and use of the operating microscope were independent predictors of mortality and reduced the risk of dying by a factor of 0.68 and 0.76, respectively. An internal thoracic artery graft resulted in a mean survival of 4.4 years longer than that with vein grafts alone. The internal thoracic artery graft compared with vein grafts was associated with fewer reoperations (p < 0.001), fewer late myocardial infarctions, lower associated mortality rates (p < 0.04) and less early recurrence of angina (p = 0.03). CONCLUSIONS: The internal thoracic artery graft and use of the operating microscope confer a superior clinical advantage over the saphenous vein graft throughout a 20-year follow-up period. The advantage of an internal thoracic artery graft does not decrease with time, suggesting that the choice of conduit at the initial operation is more important clinically than progression of coronary artery disease.

Angina Pectoris↗
PubMed1994

Case-control study of whether subfertility in men is familial.

OBJECTIVE: To test the hypothesis that subfertility in men is familial and to examine the distribution of subfertility within families for consistency with a genetic cause. DESIGN: Case-control study and segregation analysis. SETTING: Two teaching hospitals in Leeds. SUBJECTS: Cases (probands) were men with an abnormal sperm count who attended a subfertility clinic and whose partners had no major factor contravening fertility. Controls were fathers of two or more children recruited through vasectomy clinics or a maternity department. MAIN OUTCOME MEASURES: The incidence of involuntary childlessness among brothers with partners and among sisters and second and third degree male relatives. When possible clinical and laboratory details were obtained from involuntarily childless brothers. RESULTS: Seventeen of the 148 (11.5%) brothers of probands but none of the 169 brothers of controls had sought medical advice for childlessness (P < 0.0005). Four probands had more than one involuntarily childless brother. There were six further brothers whose childlessness was thought to be involuntary bringing the total prevalence of subfertility among brothers of probands to 16%. Segregation analysis was consistent with an autosomal recessive mode of inheritance accounting for 60% of subfertility in men. Seventeen of the 346 (4.9%) uncles of probands and 10 of 420 (2.8%) uncles of controls were reported to be involuntarily childless (P = 0.09), but there was no difference in childlessness among sisters. In three families sperm counts from "affected" brothers confirmed the diagnosis and showed considerable similarities within but not between families. CONCLUSION: Subfertility in men has a familial component, and the observations are consistent with an autosomal recessive mode of inheritance in over half the cases. Several different genes are probably involved.

Adult↗
PubMed1994

Implications of upright gastro-oesophageal reflux.

The presentation, oesophageal profile and management of 27 symptomatic patients with daytime (upright) gastro-oesophageal reflux only is reported. Oesophagitis was a presenting feature in 11 patients and its development was most closely correlated with postprandial reflux, which was characterized by cumulative acid exposure rather than by clearance abnormalities. Upright reflux was not associated with a hypotensive lower oesophageal sphincter or with oesophageal dysmotility. Antireflux surgery is indicated when conservative measures fail and was not associated with gas-bloat syndrome after operation.

Adult↗