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Biomedical subjects

G D Foster

Publications and source records attributed to G D Foster.

At least 91 records · Page 5Linked to original sources
PubMed1991

Long-term evaluation of cardiac function in obese patients treated with a very-low-calorie diet: a controlled clinical study of patients without underlying cardiac disease.

Twenty obese women were randomly assigned to consume (for 16 wk) either a 420-kcal/d liquid diet (n = 12) or a 1200-kcal/d balanced diet (n = 8). Thereafter, patients in both conditions were prescribed a 1200-kcal/d diet for the remainder of treatment (week 45). Six obese nondieters served as control subjects. Ambulatory electrocardiographic (Holter) monitor readings were obtained on all patients at baseline and weeks 3, 9, 13, 17, 19, and 45 of the study and were analyzed for ventricular premature depolarizations (VPDs) per hour, paired forms, and runs of ventricular tachycardia. There were no statistically significant changes in VPDs in any condition during treatment. Similarly, there were no significant changes in the PR, QRS, and corrected QT intervals. The results indicate that under appropriate medical supervision, very-low-calorie diets can be used safely for up to 16 wk by significantly obese patients free of pre-existing cardiac disease.

Diet, Reducing↗
PubMed1991

Evidence for subgenomic RNAs in leaves infected with an Andean strain of potato virus S.

The genomic RNA (7.5 kb) and two subgenomic RNA species (2.5 kb and 1.1 kb) were detected by Northern hybridization in leaves infected with an Andean strain of potato virus S (PVSA). The single-stranded RNAs contain a substantial poly-(A) tract as shown by oligo (dT)-cellulose chromatography and by an increased mobility on agarose gels following digestion with RNase H in the presence of oligo (dT). In rabbit reticulocyte lysates, the 1.1 kb RNA directed the synthesis of the 34 kD virus coat protein which was not translated efficiently from full length genomic RNA isolated by sucrose gradient fractionation.

Blotting, Northern↗
PubMed1991

Weight loss and body fat distribution: a feasibility study using computed tomography.

Computerized tomography (CT) was used to assess the effect of a loss of body weight (18.8 kg) on the size of five fat depots in 11 obese postmenopausal women: the abdominal subcutaneous and visceral depots, the pelvic subcutaneous and intrapelvic depots, and the thigh subcutaneous depot. The mean decrease in total body fat was 34 percent, with comparable decreases in total abdominal fat (33 percent) and total pelvic fat (32 percent). In the abdomen, visceral fat was reduced by 35 percent and subcutaneous fat by 33 percent. In the pelvic region, intrapelvic fat decreased by 51 percent and subcutaneous fat by 25 percent. The decrease in the size of the abdominal visceral fat depot was highly correlated with fat loss during treatment (r = 0.68). By contrast, the decrease in the size of the subcutaneous abdominal fat depot correlated less highly with fat loss. These preliminary findings suggest that obese postmenopausal women with large visceral fat depots will decrease the size of their visceral fat depots by weight reduction. This is good news since the adverse health effects of obesity are believed to be associated with visceral fat.

Adipose Tissue↗
PubMed1990

Long-term effects of dieting on resting metabolic rate in obese outpatients.

There is growing concern that dieting may adversely affect the metabolic rate and exacerbate efforts to control weight. In this study we measured the resting metabolic rate nine times over 48 weeks in 18 obese women (108.0 +/- 3.1 kg) who were randomly assigned to one of two dietary conditions. Nine patients consumed approximately 5021 kJ/d (1200 kcal/d) throughout the 48 weeks, while the other nine consumed a 1757-kJ/d (420-kcal/d) diet for 16 of the first 17 weeks and a conventional reducing diet for the remainder of treatment. All patients increased their physical activity, primarily by walking. During the first 5 weeks, the fall in metabolic rate was more than double the relative reduction in weight. By contrast, at week 48, the metabolic rate of patients in the two conditions was reduced by 9.4% +/- 4.0% and 8.3% +/- 2.2%, respectively, while weight was reduced by 16.6% +/- 2.7% and 19.5% +/- 2.7%, respectively. Thus, neither dietary regimen, combined with modest physical activity, was associated with long-term reductions in resting metabolic rate that exceeded decreases anticipated with the achievement of a lower body weight.

Adult↗
PubMed1990

A comparison of the nucleotide sequence homologies between isolates of the Andean and ordinary strains of potato virus S and their relationship to other carlaviruses.

Sequence homologies between the RNAs of five isolates of the ordinary strain of potato virus S (PVSo), four isolates of the Andean strain (PVSA), potato virus M(PVM), and the type member of the carlavirus group, carnation latent virus (CLV), were compared using cDNA solution hybridization. A high degree of homology (90-100%) was detected between the majority of PVSo and PVSA isolates, but lower levels of homology (less than 10%) were observed between PVS, PVM, and CLV.

Nucleic Acid Hybridization↗
PubMed1990

Investigation of the 5' terminal structures of genomic and subgenomic RNAs of potato virus S.

Hybrid arrest translation involving an antisense RNA, generated from a cloned cDNA close to the 5' region of potato virus S genomic RNA, blocked the synthesis of genomic encoded products but had little effect on subgenomic RNA encoded products. Similarly, the synthesis of PVS genomic RNA-directed peptides was inhibited by the cap analogue m7G5'ppp5'G, suggesting the presence of a cap structure at the 5' terminus whilst subgenomic RNA encoded products remained unaffected, suggesting an uncapped structure. This was confirmed by artificially produced uncapped subgenomic RNAs translating as efficiently in in vitro translation systems as authentic viral subgenomic RNAs.

Blotting, Southern↗
PubMed1990

Controlled trial of the metabolic effects of a very-low-calorie diet: short- and long-term effects.

Resting energy expenditure (REE), weight, and body composition were measured up to seven times in 13 obese women during a 24-wk study. Patients were randomly assigned to a very-low-calorie diet (VLCD, 500 kcal/d) or a balanced-deficit diet (BDD, 1200 kcal/d). After 8 wk of supplemented fasting, REE of the VLCD patients decreased by 17% whereas that of the BDD patients was virtually unchanged. REE of the VLCD patients increased during 12 subsequent weeks of realimentation such that differences in REE between the two groups were not statistically significant at week 24 (VLCD = -11%, BDD = -2%). Reductions in weight and fat-free mass (FFM) were 12.1% and 3.6% for the VLCD patients and 10.6% and 4.1% for the BDD patients, respectively. There were no significant differences between the groups in pre- to posttreatment changes in REE normalized to FFM. Results suggest that REE recovers partially after consumption of a VLCD. They also provide evidence of a possible metabolic advantage of weight loss by a more moderate restriction.

Body Composition↗
PubMed1990

Evidence for the role of subgenomic RNAs in the production of potato virus S coat protein during in vitro translation.

Purified virus particles of potato virus S (PVS) when disrupted yielded only one readily resolved band of 7.5 kb in ethidium bromide-stained agarose gels. However Northern hybridization of viral RNA, probed with a clone specific to the viral coat protein gene, revealed a region of subgenomic RNAs of approximately 1.3 kb. Sucrose gradient fractionation of subgenomic RNA revealed that it coded for viral coat protein when translated in vitro in rabbit reticulocyte lysate. Virus particle lengths suggest that this subgenomic RNA may be encapsidated in 100 to 220 nm particles.

Capsid↗
PubMed1990

Nucleotide sequence of the 3'-terminal region of Helenium virus S RNA.

The sequence of 1390 nucleotides of the 3'-terminal region of Helenium virus S RNA was determined from cloned cDNA. This portion of the viral RNA contains two major open reading frames (ORFs) encoding proteins of Mr 32.9K and 12.6K. The 32.9K protein, which is similar in size to the capsid protein of the virus, shares marked homology with the coat proteins of potexviruses and two other carlaviruses. The ORF, corresponding to Mr 12.6K, nearest to the 3'-terminal poly(A) tail shows extensive similarity with the corresponding proteins of potato virus S and potato virus M. We propose that this protein may be involved in nucleic acid binding within infected cells.

Amino Acid Sequence↗
PubMed1990

Effects of a very low calorie diet on weight, thyroid hormones and mood.

Changes in weight, thyroid hormones and mood were examined in 15 obese (113 kg) women over an 18-week period. After 4 weeks of a 1200 kcal/day diet, patients were randomly assigned to one of two dietary conditions: very low calorie diet (VLCD) (n = 8) or balanced deficit diet (BDD) (n = 7). VLCD patients consumed 400 kcal/day for 8 weeks and then gradually returned to a 1200 kcal/day diet. BDD patients consumed 1200 kcal/day for the entire 18 weeks. Differences in weight losses between the conditions were statistically significant only during the consumption of the VLCD. Serum T3 decreased by as much as 66 percent in VLCD patients during consumption of the 400 kcal/day diet, whereas rT3 increased by as much as 27 percent. T3 increased when patients were realimented with a 1000 kcal/day balanced diet but remained a significant 22 percent below baseline at the end of the study. BDD patients also showed marked reductions in T3, as great as 40 percent, so that the differences between the two conditions were not statistically significant. Multiple regression analyses, collapsing across conditions (n = 15), indicated that weight loss at week 12 and baseline T3 accounted for 63 percent of the variance in the change in T3 at week 12. Patients in both conditions showed improvements in mood. Changes in depression were not associated with changes in serum T3.

Adult↗
PubMed1989

Insulin and the regulation of glycogen metabolism and gluconeogenesis in American eel hepatocytes.

The regulation of glycogenolysis and alanine and lactate gluconeogenesis, glycogenesis, and oxidation by porcine insulin was studied in isolated American eel hepatocytes. Experiments were performed in the summer, winter, and spring using naturally fluctuating water temperatures to establish the seasonal dependence of these processes and their hormone sensitivities. Porcine insulin (10(-8) M) maintained glycogen content, decreased total glucose production, increased lactate and alanine flux to glycogen in hepatocytes from summer and winter eels, and had a small stimulatory effect on alanine gluconeogenesis in the spring. The hormone counteracted bovine glucagon-stimulated glycogen depletion and glucose production, but only offset the glucagon effect on gluconeogenesis when glycogen content was below summer values. Effects of the two hormones on oxidation were additive in the summer, but were equivocal at other seasons. The magnitudes of the hormone effects on metabolism were generally smaller in the winter than in the other seasons. Anglerfish glucagon (10(-8) M) effects, studied in the spring, mimicked those of bovine glucagon. Porcine insulin effects in the presence of anglerfish glucagon were the same as in the presence of bovine glucagon. These studies generally support the antagonistic role between insulin and glucagon and the insulin-stimulated C3 precursor flux to glycogen reported in mammalian hepatocytes. Although these metabolic processes are seasonally adjusted, the precise mechanism involved is not understood.

Alanine↗
PubMed1989

The regulation of 6-phosphofructo-1-kinase by insulin and glucagon in isolated hepatocytes of the American eel.

Kinetic characteristics of American eel liver 6-phosphofructo-1-kinase (PFK-1) and the effects of porcine insulin, bovine glucagon, and dibutyryl-cAMP were studied. At 0.1 mM ATP, kinetics were sigmoidal with respect to fructose-6-phosphate (F-6-P) concentrations and the S0.5 (F-6-P) increased with higher ATP concentrations. At 2 mM F-6-P, optimal ATP concentrations were 0.1 mM, with maximal inhibition at 0.5 mM. Fructose 2,6-bisphosphate (Fru-2,6-P2) offset ATP inhibition and activated the enzyme, changing F-6-P kinetic curves from sigmoidal to hyperbolic. At 2 mM F-6-P and 0.1 mM ATP the Fru-2,6-P2 activation curve was hyperbolic with a Ka of approximately 1 microM. In isolated hepatocytes, porcine insulin decreased the sensitivity of PFK-1 to ATP, an effect that was offset when bovine glucagon was also present. Insulin, alone and with glucagon, increased the Fru-2,6-P2 activation ratio. In the presence of glucagon, insulin increased Fru-2,6-P2 concentrations in hepatocytes. These effects suggest that PFK-1 is a potential regulatory point for hormones in the control of carbohydrate metabolism in the American eel liver.

Anguilla↗
PubMed1989

Treatment of obesity by very low calorie diet, behavior therapy, and their combination: a five-year perspective.

Seventy-six obese women with a mean age of 42.1 years and weight of 106.0 kg were randomly assigned to one of three treatments: (a) very low calorie diet alone; (b) behavior therapy alone; or their combination (i.e. combined treatment). Weight losses for the three conditions at the end of treatment were 13.1, 13.0, and 16.8 kg, respectively, with losses for combined treatment significantly greater than those for the two other conditions. Weight losses 1 year after treatment were 4.7, 6.6, and 10.6 kg, respectively. A significantly greater percentage of subjects in the behavior therapy alone (36 percent) and combined treatment conditions (32 percent) maintained their full end-of-treatment weight losses than in the very low calorie diet alone condition (5 percent). Five years after treatment, a majority of subjects in all three conditions had returned to their pretreatment weight, and 55 percent of the total sample had received additional weight reduction therapy. The short and long term effects of treatment are discussed in terms of their implications for practice and research.

Adult↗
PubMed1989

Dissatisfaction with weight and figure in obese girls: discontent but not depression.

This study examined psychological functioning and satisfaction with weight and figure in a total of 393 obese and nonobese adolescent girls from lower-middle to middle-class families. No significant differences were observed between the two groups on measures of trait anxiety or depression, and all subjects scored well within normal limits. Obese girls did, however, report significantly greater dissatisfaction with their weight and figure than did nonobese girls. Many nonobese girls also expressed dissatisfaction with their weight, supporting the view that women's dissatisfaction with weight is a 'normative discontent'. Nearly 70 percent of the total sample had attempted to lose weight in the past year. The results of this study indicate that obese girls in the general population are dissatisfied with their weight but are not significantly anxious or depressed, as had been suggested by studies of overweight adolescents in clinical settings.

Adolescent↗
PubMed1988

Resting energy expenditure, body composition, and excess weight in the obese.

This study investigated differences between measured and predicted resting energy expenditure (REE) in 80 women who averaged 104.6 kg in weight and were 49 kg and 88% overweight. Body composition analysis showed that 68% of the excess weight was fat and 32% was fat-free mass (FFM). Normalized for height, total body potassium (TBK) was 113 +/- 15% and total body water (TBW) was 133 +/- 21% of values in nonobese controls. The health of the FFM, defined as the potassium content per kg of FFM, was 84 +/- 13% of normal. Measured and predicted REE were only modestly related (r = +.59), and only 59% of measured REEs were within 10% of predicted values. A stepwise multiple regression indicated that weight was the single best predictor of measured REE and that the size of the FFM made a significantly greater contribution to REE than did the size of the fat mass. Commonly used equations for the prediction of REE are not appropriate for moderately or severely obese patients. Caloric prescription for weight reduction must be tailored to individuals rather than recommending the same caloric intake to persons with varying metabolic rates.

Adipose Tissue↗
PubMed1987

Metabolism in sea raven (Hemitripterus americanus) hepatocytes: the effects of insulin and glucagon.

The metabolism of the sea raven, Hemitripterus americanus, hepatocyte preparation was studied, emphasizing the roles of insulin and glucagon on carbohydrate status. Sea raven hepatocyte glycogen was depleted throughout the preincubation and 2-hr incubation period in the presence of either glucose or serine. Bovine glucagon stimulated glycogen loss and increased glucose levels and serine flux to glucose. Porcine insulin prevented glycogen depletion at least over 1.5 hr of incubation, but did not affect glucose levels in the hepatocytes. It also significantly increased serine flux to glucose, glycogen, and protein, and alanine flux to glucose, CO2, and protein. Teleost insulin did not alter the pattern of hepatic glycogen depletion, while it did increase glucose levels and serine flux to glucose, glycogen, and lipids, and alanine flux to CO2 and glucose. Both glucagon and porcine insulin increased glucose flux to glycogen, but neither altered glucose conversion to CO2, lactate, or protein. The teleost insulin had no effect on glucose conversion to any product tested. Teleost insulin had an additive effect on the glucagon-induced increases in total glucose production and gluconeogenesis from serine, while glucagon offset the insulin stimulation of serine flux to glycogen and CO2. The results demonstrate that glucagon functions to increase glucose production from gluconeogenic precursors and glycogen in sea raven hepatocytes, while insulin demonstrates anabolic effects through gluconeogenic precursors. It is suggested that insulin functions in sea raven hepatocytes to increase glycogen stores through increased amino acid utilization and/or to increase glucose production for transport to, and storage in, glucose-utilizing tissues (e.g., muscle). An antagonism between insulin and glucagon on the glycolytic/gluconeogenic pathways as is found in mammalian livers is not as clear in sea raven hepatocytes. These findings are consistent with the carnivorous diet of the sea raven and a preferentially gluconeogenic role for the liver of this species.

Animals↗
PubMed1987

Caloric requirements in total parenteral nutrition.

Resting energy expenditure (REE) was measured in 100 consecutive total parenteral nutrition (TPN) patients. Only forty-eight percent of the measured REEs were within 90-110% of the predicted Harris-Benedict values. A literature review revealed 191 published guidelines for non-protein caloric requirements of hospitalized TPN patients. These guidelines were appropriately matched and applied to the 100 individual TPN patients. The relationship between the recommended caloric supply and measured caloric expenditure was minimal. The recommendations exceeded measured REE by an average of 1076 +/- 660 kcal/day. These published guidelines were substantially above and below caloric requirements based on measured REE for both fat maintained (130% REE) and fat depleted (150% REE) patients. Following published guidelines rather than standards based on measured REE results in the administration of 6947 excess liters of TPN per year. Improvement in the precision of TPN caloric prescription can be accomplished by using measured REE as a reference base. When published guidelines were compared to prescriptions based on measured REE it was found that published guidelines were inaccurate both overall and individually and a substantial cost savings justifies actual measurement of energy needs.

Adipose Tissue↗