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Biomedical subjects

G D Foster

Publications and source records attributed to G D Foster.

At least 55 records · Page 3Linked to original sources
PubMed1997

Deletion analysis of a translational enhancer upstream from the coat protein open reading frame of potato virus S.

We have previously demonstrated that the 101 nucleotides upstream from the ATG of the potato virus S (PVS) coat protein gene has the ability to act as a translational enhancer in vitro and in vivo when fused to a range of marker genes. These 101 nucleotides, which have been designated VTE (viral translational enhancer), contain a block of nucleotide homology that is conserved between members of the carlavirus group, centered around a core sequence of CCTTTAGGTT. When deletions were generated that lacked 47 of the 5' nucleotides, but still retained the conserved block, and analysed in vitro and in vivo, it was observed that these leaders had lost their ability to act as translational enhancers. These results suggest that the sequences 5' to the conserved block may be acting as a translational enhancer or may be important in placing the conserved block in optimal context. This is confirmed to some extent by hybrid arrest translation results in which the effects on translation of oligonucleotides, complementary to regions within the VTE leader, were investigated. It was observed that oligonucleotides complementary to the nucleotides 5' to the conserved block had a dramatic effect on the translational competence of transcripts derived from VTE-luciferase constructs, decreasing levels by 53%, whereas oligonucleotides complementary to sequences 3' to the conserved block reduced levels of translation by only 15.6%.

Base Sequence↗
PubMed1997

A CaMV 35S promoter driven cDNA clone of tobacco mosaic virus can infect host plant tissue despite being uninfectious when manually inoculated onto leaves.

Leading from the success of inoculating plants with viral RNA transcribed in vitro from full length cDNA clones, attempts have been made to build cDNA clones which are directly infectious by inoculation. However, we and others have found that viral cDNA clones driven by the CaMV 35S promoter were able to infect some host plants yet not others, when manually inoculated onto leaves. Alternative methods including microprojectile bombardment have been used to deliver an infectious TMV construct into plant cells resulting in the infection of all TMV host plants tested. Lack of infection via manual inoculation may be due to unsuccessful delivery of a viable construct into the plant cell nucleus.

DNA, Complementary↗
PubMed1997

What is a reasonable weight loss? Patients' expectations and evaluations of obesity treatment outcomes.

Expert panels and governmental guidelines now recommend that obese persons seek modest (i.e., "reasonable") reductions in body weight rather than striving for "ideal" weights. Little is known, however, about patients' views of what is a "reasonable" weight loss. This study assessed patients' goals, expectations, and evaluations of various outcomes before, during, and after 48 weeks of treatment. Before treatment, 60 obese women (99.1 +/- 12.3 kg; body mass index of 36.3 +/- 4.3 kg/ m2) defined their goal weight and 4 other weights: "dream weight"; "happy weight"; "acceptable weight"; and "disappointed weight." Goal weight averaged a 32% reduction in body weight. A 17-kg weight loss was defined as disappointed; a 25-kg loss, was acceptable. After 48 weeks of treatment and a 16-kg weight loss, 47% of patients did not achieve even a disappointed weight. These data illustrate the dramatic disparity between patients' expectations and professional recommendations and the need to help patients accept more modest weight loss outcomes.

Adult↗
PubMed1997

Exercise in the treatment of obesity: effects of four interventions on body composition, resting energy expenditure, appetite, and mood.

This study investigated changes in body composition, resting energy expenditure (REE), appetite, and mood in 128 obese women who were randomly assigned to 1 of 4 treatment conditions: diet alone, diet plus aerobic training, diet plus strength training, or diet combined with aerobic and strength training (i.e., combined training). All women received the same 48-week group behavioral program and were prescribed the same diet. Exercising participants were provided 3 supervised exercise sessions per week for the first 28 weeks and 2 sessions weekly thereafter. Participants across the 4 conditions achieved a mean weight loss of 16.5 +/- 6.8 kg at Week 24, which decreased to 15.1 +/- 8.4 kg at Week 48. There were no significant differences among conditions at any time in changes in weight or body composition. Women who received aerobic training displayed significantly smaller reductions in REE at Week 24 than did those who received strength training. There were no other significant differences among conditions at any time on this variable or in changes in appetite and mood.

Adult↗
PubMed1997

Body image in obese women before, during, and after weight loss treatment.

Body image, as measured by the Appearance Evaluation and Body Areas Satisfaction scales of the Multidimensional Body-Self Relations Questionnaire (T.F. Cash, 1994b), was assessed in 59 obese women before, during, and after 48 weeks of weight loss treatment. Before treatment, positive ratings of body image were associated with higher levels of self-esteem, lower levels of dysphoria, and fewer previous diets. After 24 weeks and a mean weight loss of 19.4 kg (SD = 6.5), participants showed significant (p < .0001) improvements in body image. A small weight gain from Week 24 to Week 48 was associated with a slight but significant worsening in both measures of body image. Nevertheless, after 48 weeks and a mean weight loss of 16.3 kg (SD = 7.1), body image was significantly improved from baseline (p < .0001). Changes in body image were not related to changes in weight. Future studies are needed to separate the effects of treatment and weight loss on body image in obese persons.

Adult↗
PubMed1997

3'-Terminal sequences of the RNA genomes of narcissus latent and Maclura mosaic viruses suggest that they represent a new genus of the Potyviridae.

The nucleotide sequences of part of the nuclear inclusion body b (NIb) gene, the complete coat protein gene and the 3' untranslated regions of narcissus latent virus (NLV) and Maclura mosaic virus (MacMV) were determined. Deduced amino acid sequences for the NIb and coat protein genes revealed that NLV and MacMV are closely related. Gel analysis and Western blotting of the coat proteins of NLV and MacMV from infected tissue or purified virus indicated that they have molecular masses of 39.5 kDa and 40 kDa (respectively), whereas estimates from deduced amino acid sequences suggested that they have molecular masses of 32.8 kDa and 34.1 kDa. Comparison of the NIb and coat protein sequences with other viruses showed that NLV and MacMV have close affinities with viruses of the Potyviridae and suggests that they should form a new genus of the family.

Amino Acid Sequence↗
PubMed1996

Effects of weight cycling on the resting energy expenditure and body composition of obese women.

OBJECTIVE: Numerous reports have suggested that cycles of weight loss and regain (i.e., weight cycling) are associated with adverse health consequences, a concern that may lead some obese individuals to forgo weight control efforts. The present study examined whether weight cycling was associated with a reduction in resting energy expenditure (REE) and with increases in both total and upper body fat. METHOD: REE, body composition, and body fat distribution were measured before and after weight loss, and following full weight regain, in 12 women who before treatment had a mean (+/- SEM) age of 38.8 +/- 3.4 years and weight of 98.0 +/- 3.2 kg. RESULTS: At the end of treatment, patients lost 18.9 +/- 2.6 kg which was comprised of significant decreases in body fat and fat-free mass of 15.2 +/- 2.2 and 3.7 +/- 0.8 kg, respectively (both ps < .001). REE also fell during this time from 1,631 +/- 82 to 1,501 +/- 51 kcal/d (p < .03). All of these measures, however, returned to their baseline values when patients regained their lost weight. Body fat distribution was unchanged throughout the study. DISCUSSION: These results do not support claims that weight cycling adversely affects REE, body composition, or body fat distribution.

Adipose Tissue↗
PubMed1996

Are obese adolescent boys ignoring an important health risk?

OBJECTIVE: The present study assessed satisfaction with weight, shape, and physical appearance, as well as the frequency of weight reduction efforts, in four well-defined groups of adolescents: (1) normal-weight girls; (2) normal-weight boys; (3) obese girls; and (4) obese boys. METHOD: Subjects were selected from 453 females and 355 males from a parochial school. In addition to the measurements of height and weight, adolescents completed a series of questionnaires on weight and dieting, weight and figure satisfaction, parents' attitudes toward weight, and anxiety. RESULTS: Only 49% of obese boys had tried to lose weight over the past year as compared to 90% of the obese girls (p < .001). Only 13% of the obese boys were currently dieting as compared to 62% of the obese girls (p < .001). Despite the relative equivalence of weight in the obese boys and girls, the boys perceived themselves to be less overweight (p < .05) and happier with their looks (p < .001) than obese girls. Thirty-three percent of normal-weight girls were dieting, and 70% had attempted weight loss over the past year. They were significantly less happy with their weight and figure than were average-weight boys (p < .001) and, remarkably, did not differ significantly from overweight boys on these measures. DISCUSSION: Obese adolescent males, in particular, need to be educated about the potential liabilities of their excess weight and encouraged to take appropriate action to correct it.

Adolescent↗
PubMed1996

Hydrophobic organochlorine compounds sequestered in submersed aquatic macrophytes (Hydrilla verticillata (L.F.) Royle) from the tidal Potomac River (USA).

The potential for hydrophobic organochlorine contaminants to be sequestered in submersed aquatic vegetation was evaluated by determining the concentrations of cis- and trans-chlordane, dieldrin, and polychlorinated biphenyls (PCBs) in feral aquatic macrophytes (Hydrilla verticillata (L.f.) Royle) collected from the tidal Potomac River. Similarities in mean dry-weight concentrations of the identified organochlorine compounds in H. verticillata and surrounding alluvial sediments indicated that the extent of sequestration in H. verticillata was of the same magnitude as sorption of these compounds to river sediments, but some qualitative differences in PCB congener profiles existed. The results imply that to some degree H. verticillata can influence downstream fluxes of organic contaminants in fluvial transport in the Potomac River, and, furthermore, identify this species as a viable candidate organism for hydrophobic organochlorine contaminant biomonitoring in the Chesapeake Bay estuary.

Journal Article↗
PubMed1996

Psychological effects of weight loss and regain: a prospective evaluation.

This study prospectively assessed the psychological effects of weight loss and regain (i.e., weight cycling) in obese women. Measures of mood, binge eating, restraint, disinhibition, and hunger were obtained from 55 participants at baseline, after 6 months of treatment, and 58 months posttreatment. Women lost 21.1 +/- 8.4 kg after 6 months of treatment but were 3.6 +/- 10.9 kg above baseline weight at the time of the follow-up. Contrary to expectations, after this 21-kg cycle of weight loss and regain, women reported significant improvements in mood and binge eating, as well as reductions in hunger and disinhibition. Restraint was unchanged from baseline to follow-up. These data suggest that weight loss and regain are not associated with long-term adverse psychological effects. The findings also confirm earlier reports of significant weight regain after treatment and underscore the need for research to improve the maintenance of weight loss.

Feeding Behavior↗
PubMed1996

Maturation-specific translational enhancement mediated by the 5'-UTR of a late pollen transcript.

The tomato lat52 gene encodes an abundant protein specifically expressed in the vegetative cell of the pollen grain during pollen maturation which is essential for normal pollen tube growth. Multiple upstream cis-regulatory elements controlling the level and specificity of lat52 transcription have previously been identified. This research investigated the role of the 5'-untranslated region (5'-UTR) in controlling lat52 expression. In transient expression assays, gene fusion constructs containing the lat52 5'-UTR were expressed in pollen at levels 13- to 60-fold above those in which synthetic polylinker sequences replaced the lat52 5'-UTR. This enhancement was shown to be independent of both the promoter sequences, the linked reporter gene and the 3'-UTR. Analysis of RNA and protein levels in transgenic plants containing such gene fusions demonstrated that the lat52 5'-UTR conferred a dramatically increased translational yield to heterologous transcripts in a pollen-specific and strictly developmentally regulated manner during the final stages of pollen maturation. These results represent a novel example of translational enhancement in plants in that translational yield is regulated developmentally in a cell-specific manner via sequences located within the 5'-UTR.

Gene Expression Regulation, Plant↗
PubMed1996

Psychosocial consequences of weight reduction: how much weight loss is enough?

We reviewed the psychosocial consequences of weight reduction and concluded that weight loss is usually associated with improvements in mood in significantly obese individuals (> or = 20% overweight) who are treated by diet and lifestyle modification. Less is known about the psychologic effects of weight loss in mildly overweight individuals who reduce their weight on their own but the limited data suggest similarly positive effects. We recommend that significantly obese individuals seek a 10% reduction in body weight, a loss that is likely to be associated with improvements in psychologic as well as physical health. A loss of this magnitude is typically produced by 16-20 wk of treatment by diet and behavior modification. Persons who ae mildly overweight (particularly those with health complications) are encouraged to reduce their weight by increasing their physical activity. Exercise is associated with modest but long-term weight losses and with improvements in mood and physical health. The recommendation that overweight Americans seek a healthier weight should be combined with efforts to promote healthier attitudes toward weight and shape in normal-weight women and girls.

Affect↗
PubMed1995

Sertraline and relapse prevention training following treatment by very-low-calorie diet: a controlled clinical trial.

This study examined the combination of sertraline, a selective serotonin reuptake inhibitor, and relapse prevention training in the maintenance of weight loss following treatment by a very-low-calorie diet. A total of 53 women who had lost a mean (+/- SD) of 22.9 +/- 7.1 kg from a pretreatment weight of 103.1 +/- 17.8 kg were randomly assigned to a 54-week weight maintenance program that was combined with either: 1) 200 mg/d of sertraline; or 2) placebo. During the first 6 weeks, sertraline subjects lost significantly more weight and reported significantly greater reductions in hunger and preoccupation with food than did subjects on placebo. After this time, however, women in both conditions regained weight steadily. The 13 sertraline subjects who completed the 54-week study regained 17.7 +/- 10.6 kg of their original 26.3 +/- 7.6 kg loss, equal to a regain of 70.9 +/- 41.7%. The 17 placebo completers regained 11.8 +/- 9.0 kg of their 23.4 +/- 7.8 kg loss, equal to a 46.5 +/- 34.6% regain. End-of-treatment differences between groups in weight change were not statistically significant. Nor were there significant differences between the two conditions at any time in changes in fat-free mass, resting metabolic rate or dysphoria, all of which tended to increase with weight regain. The results are discussed in relation to findings from other long-term studies that combined diet and medication.

1-Naphthylamine↗
PubMed1995

The potential exploitation of plant viral translational enhancers in biotechnology for increased gene expression.

The regulation of gene expression is extremely important for all organisms, not least for viruses that require a maximum rate of production of viral proteins to allow rapid multiplication and spread. Single-stranded positive-sense RNA viruses contain specific nucleotide sequences that can be used to elevate the expression of vital gene products to required high levels. Among plant viruses, translational enhancement has been documented widely, especially over the past few years. Reported candidates include one of the best known and most intensely researched virus, tobacco mosaic virus, members of the potyvirus group, and even a small satellite RNA of tobacco necrosis virus. Enhancement values range from 2-100-fold with different viruses, different reporter genes, and in different systems. Research indicates that an absence of secondary structure alone does not explain translational enhancement and despite attempts to determine the mechanism by which this enhancement occurs very little conclusions can be made as yet. Whatever the mechanism, the presence of these sequences upstream from an open reading frame results in an elevated level of protein production and may feature as important tools for biotechnology in the future.

Base Sequence↗
PubMed1995

The energy cost of walking before and after significant weight loss.

The purpose of this study was to determine whether significant weight loss reduced the energy cost of activity more than that expected based on decreased body weight. Standing energy expenditure was measured and subtracted from the total energy cost of walking to determine ambulatory energy expenditure (AEE). The energy cost of walking was determined in 11 obese women at baseline, week 9 [after 8 wk of a 1758-3349 kJ.d-1 diet], and week 22 (after 2 wk of weight stability). AEE accounted for 80% of the energy cost of walking. Body weight was the principal determinant of AEE, but the relationship was not 1:1. Subjects reduced body weight by 13% at week 9 and 21% at week 22. Analyses which controlled for the relationship between AEE and weight at baseline, showed no change in AEE at week 9. By contrast, at week 22, AEE was reduced more than expected based on a lower body weight. These findings suggest that after significant weight loss, reduced-obese persons will expend less energy for the same activity, even after accounting for the decrease in body weight. These data also suggest that weight-based estimates of exercise energy expenditure may be inappropriate after significant weight loss.

Adult↗
PubMed1994

Analysis of a translational enhancer upstream from the coat protein open reading frame of potato virus S.

Evidence has suggested that the subgenomic RNA of the carlavirus potato virus S is an efficient message for the coat protein, even though evidence suggests it is uncapped at its 5' terminus. We have investigated the effect of the upstream region of the coat protein gene of potato virus S on the level of reporter gene expression in vitro. The region of 101 nucleotides upstream of the coat protein, designated VTE (viral translational enhancer) was found to increase levels of translation in comparison to a synthetic leader when linked to the beta-glucuronidase (GUS) reporter gene in vitro in rabbit reticulocyte and wheat germ lysate. VTE was also able to increase translation of the reporter gene luciferase (LUC) in vitro above the levels obtained for both a synthetic leader and a leader obtained from a plant gene isolated from Arabidopsis thaliana. The level of enhancement was evident with both capped and uncapped transcripts. When the VTE sequence was deleted to 20 nucleotides of the upstream region, thus removing the nucleotide block homologous among carlaviruses, the ability to enhance levels of translation was removed. In vitro translation studies indicated that the translational enhancement activity of VTE was at least partially cap independent. Translation of VTE linked to reporter genes in the presence of cap analogue was relatively unaffected whereas synthetic leader and a plant leader constructs were both more sensitive. In vitro competition analysis revealed that when short RNA transcripts representing the 101 nucleotides of VTE were added in trans to functional VTE leader LUC constructs there was a marked decrease in the level of translation when compared with a synthetic leader added in trans. These results suggest that the upstream region of the coat protein ORF of potato virus S promotes translation in a cap-independent manner that may involve the binding of proteins and/or ribosomes to the 101 nucleotides of the VTE sequence.

Animals↗
PubMed1994

In vivo characterisation of a translational enhancer upstream from the coat protein open reading frame of potato virus S.

The 101 nucleotide region upstream from the ATG of the potato virus S (PVS) coat protein gene was isolated and the effect of this region on the translation of a downstream open reading frame analysed in vivo. Translation was monitored using the reporter genes B-glucuronidase (GUS) and luciferase (LUC). Translational enhancement was assayed transiently using DNA microprojectile bombardment into both leaf and pollen tissue and also by polyethylene glycol mediated transfection of tobacco protoplasts. In both cases the presence of this region resulted in a 2-3 fold increase in translation when compared to reporter expression with synthetic leader and authentic plant leader constructs. Tobacco plants stability transformed with this PVS 101 nucleotide region and downstream GUS gene gave 4 times the level of translation over synthetic leader GUS control plants.

Base Sequence↗