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Biomedical subjects

V S Hubbard

Publications and source records attributed to V S Hubbard.

At least 19 recordsLinked to original sources
PubMed2002

Body composition estimates from NHANES III bioelectrical impedance data.

BACKGROUND: Body composition estimates for the US population are important in order to analyze trends in obesity, sarcopenia and other weight-related health conditions. National body composition estimates have not previously been available. OBJECTIVE: To use transformed bioelectrical impedance analysis (BIA) data in sex-specific, multicomponent model-derived prediction formulae, to estimate total body water (TBW), fat-free mass (FFM), total body fat (TBF), and percentage body fat (%BF) using a nationally representative sample of the US population. DESIGN: Anthropometric and BIA data were from the third National Health and Nutrition Examination Survey (NHANES III; 1988-1994). Sex-specific BIA prediction equations developed for this study were applied to the NHANES data, and mean values for TBW, FFM, TBF and %BF were estimated for selected age, sex and racial-ethnic groups. RESULTS: Among the non-Hispanic white, non-Hispanic black, and Mexican-American participants aged 12-80 y examined in NHANES III, 15 912 had data available for weight, stature and BIA resistance measures. Males had higher mean TBW and FFM than did females, regardless of age or racial-ethnic status. Mean TBW and FFM increased from the adolescent years to mid-adulthood and declined in older adult age groups. Females had higher mean TBF and %BF estimates than males at each age group. Mean TBF also increased with older age groups to approximately 60 y of age after which it decreased. CONCLUSIONS: These mean body composition estimates for TBW, FFM, TBF and %BF based upon NHANES III BIA data provide a descriptive reference for non-Hispanic whites, non-Hispanic blacks and Mexican Americans in the US population.

Adolescent↗
PubMed1997

Derivation of daily values used for nutrition labeling.

Daily Values (DVs) are the daily dietary intake standards used for nutrition labeling. Information on the derivation of DVs is important for dietetics professionals and nutrition educators who use DVs to educate and instruct patients and students about diet planning and evaluation and about adherence to modified diets. The first daily intake standards for nutrition labeling were established in 1973 and were referred to as the US Recommended Daily Allowances (US RDAs). They were based on the 1968 Recommended Dietary Allowances (RDAs) developed by the National Academy of Sciences. These intake standards were mandatory for 8 and optional for 12 food components on nutrition labels. Regulations revising the daily intake standards for nutrition labeling were published in 1993. The new standards included Reference Daily Intakes (RDIs) for 19 food components and Daily Reference Values (DRVs) for 8 food components. The RDIs were based on the 1973 US RDAs, and the DRVs were based on consensus recommendations. On the nutrition label, the RDIs and DRVs are referred to as DVs. Percent DVs are mandatory on nutrition labels for 10 food components and optional for 16 food components. In 1995, DVs were established by regulation for 6 additional food components; these DVs are optional for nutrition labels. The DVs established in 1995 were based on information from the 1980 and 1989 revisions of the RDAs and Estimated Safe and Adequate Daily Dietary Intakes. Currently, percent DVs are mandatory on nutrition labels for 10 food components and optional for 22. Optional percent DVs become mandatory if claims are made about the food components or if the food components are added to the food through fortification or as food additives.

Diet↗
PubMed1996

Differences in body composition of black and white girls.

Adults have racial differences in body composition that may modulate risks resulting from obesity. Although black and white children have been shown previously to have differences in bone mineral density and subcutaneous body fat, differences in visceral adipose tissue have not been evaluated. We studied 20 black and 20 white normal-weight girls aged 7-10 y, who were matched for weight, body mass index (BMI), bone age, chronological age, Tanner breast stage, and socioeconomic status. Each underwent anthropometric measurements, bioelectrical impedance analysis, dual-energy X-ray absorptiometry (DXA), and abdominal magnetic resonance imaging (MRI) for determination of total (TAT), visceral (VAT), and subcutaneous (SAT) adipose tissue. Serum lipids and fasting and 2-h oral-glucose-tolerance test (OGTT) glucose and insulin concentrations were also measured. There were no differences between groups in absolute waist circumference or waist-to-hip ratio, but waist-to-thigh ratio was smaller in black than in white girls. Black girls had greater bone mineral density and less TAT, VAT, and SAT than whites. VAT was not significantly correlated with any measure of insulin, or with serum lipids. However, both basal and 2-h OGTT serum insulin were significantly correlated with SAT as assessed by MRI in black girls (r2 = 0.46 for basal insulin, P = 0.001: r2 = 0.31 for 2-h insulin, P = 0.01) but not in white girls (r2 < 0.05, for basal and 2-h insulin, NS). We conclude that there are significant racial differences in body composition and differences in the strength of association between abdominal adipose tissue depots and insulin sensitivity in black and white girls.

Abdomen↗
PubMed1995

Visceral adipose tissue differences in black and white women.

Fat distribution and metabolic variables were studied in 8 black and 10 white age- and weight-matched obese women undergoing a 6-mo weight-reducing regimen. Fat patterning was determined by using anthropometry and computed tomography to quantitate total, subcutaneous, and visceral adipose tissue (VAT) areas at the L2-L3 and L4-L5 levels of the lumbar spine, before, during, and after a modified fast. Black women had smaller depots of VAT than white women at both the L2-L3 (P = 0.004) and L4-L5 (P = 0.054) sites. Differences persisted after an average 17.2-kg weight loss. Although waist-hip ratio was similar in both groups, black women had 23% less VAT than white women (P = 0.007). Black women had significantly lower plasma glucose (P = 0.031) and triglycerides (P = 0.006) with significantly higher plasma high-density-lipoprotein concentrations (P < 0.001). Data from this study suggest that racial differences exist in VAT and metabolic risk factors for obesity-related illness.

Adipose Tissue↗
PubMed1994

Cystic fibrosis and phosphatidylcholine biosynthesis.

The cystic fibrosis (CF) gene defect may be associated with a defect in membrane recycling. We have investigated the metabolism of the main constituent of plasma membrane, phosphatidylcholine (PC). In this study of platelets and fibroblasts, we show an increased uptake of choline into PC of CF cells as compared with normal cells. No accumulation of PC was seen. Other patients with respiratory disease (not CF) showed normal rates of incorporation of choline into platelet PC. Platelets from heterozygote individuals showed intermediate turnover rates of choline incorporation into PC. The increase in choline incorporation into PC in CF platelets was not due to modified or increased sensitivity to either cAMP or prostaglandin E2. The total amount and the proportions of the major phospholipids in platelets of control and CF individuals were identical. These findings indicate an increased turnover rate of this phospholipid in CF cells rather than an increased net synthesis.

Base Sequence↗
PubMed1994

Report on the NIH Workshop on Pharmacologic Treatment of Obesity.

A National Institutes of Health workshop on pharmacologic treatment of obesity concluded that pharmacologic agents may be effective in reducing body weight over an extended period of time. Drugs should be used as only one component of a comprehensive weight-reduction program, and additional research is needed on the long-term efficacy and safety of drugs for obesity, and especially for combinations of drugs. Improvement in comorbidities and risk factors of obesity should be used along with weight reduction as an outcome measure in clinical trials. Industry, professional societies, and governmental agencies should work together to explore the potential for drugs for obesity and to reassess the regulatory and administrative controls on the use of currently available drugs for obesity and on the approval process for future drugs.

Animals↗
PubMed1994

Effect of fatty acids on insulin release: role of chain length and degree of unsaturation.

The purpose of the present study was to examine the role played by structural differences among fatty acids in their effect on insulin secretion by isolated perifused murine islets. Insulin secretion measured by radioimmunoassay was assessed either as total insulin output (ng.6 islets-1.20 min-1) or as percent of basal insulin secretion. Raising the glucose concentration from a basal 5.5 to 27.7 mM caused an increase of insulin output from 6.69 +/- 1.59 to 19.92 +/- 4.99 ng.6 islets-1.20 min-1 (P < 0.05) in control (untreated) islets. However, after 20-min exposure of islets to 5 mM 16:0 or 18:2, the effect of 27.7 mM glucose was enhanced or diminished, respectively. Basal insulin output (100% basal) changed to 44 +/- 10% basal (P < 0.005) with the addition of 5 mM 4:0 but was not altered when 4:0 was replaced by 6:0. Insulin output increased modestly with 5 mM 8:0 but significantly (P < 0.05) with 10:0 until a maximal of 280 +/- 24% basal with 12:0 (P < 0.01), then fell to 110 +/- 18 and 93 +/- 15% basal (P < 0.05) with 14:0 and 16:0, respectively. The addition of 5 mM 18:0 inhibited insulin secretion to 30 +/- 10% of basal (P < 0.003), and this effect was not caused by fatty acid interference with insulin assay.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Characterization of the insulinotropic potency of polyunsaturated fatty acids.

In this study we have assessed the individual abilities of the essential fatty acids, linoleic and linolenic acids, to release insulin and compared their insulinotropic potencies with those of the more established nutrient insulin secretagogues, glucose and arginine. In each experiment, a total of six islets microdissected from three mice were preperifused at the rate of 1 ml/min with Krebs-Ringer bicarbonate buffer, pH 7.4, containing 2% bovine albumin and 5.5 mM glucose (basal) with a continuous supply of 95% O2-5% CO2 at 37 C for 1 h. After collecting basal samples, the effects of 27.7 mM glucose, 20 mM arginine, 10 mM linoleic acid (18:2, omega 6), and 5 mM linolenic acid (18:3, omega 3) were tested using a sandwich protocol that entails 20-min alternating periods of stimulation with a secretagogue and a washout with basal perifusion. These nutrient concentrations were selected from initial experiments performed to characterize their dose-response effects on insulin secretion. Effluent samples were collected throughout each experiment for measurement of insulin by RIA. In one series of experiments, islets were challenged three times with 27.7 mM glucose, 10 mM linoleic acid, and 5 mM linolenic acid. In another set of experiments, islets were perifused with 20 mM arginine, 27.7 mM glucose, and 10 mM linoleic acid. All of these nutrients stimulated insulin release in a dose-dependent manner. In comparing the insulinotropic potencies of these secretagogues, we assessed insulin secretion as the integrated areas under the curve during 20 min of perifusion with a given nutrient. Thus, the mean integrated area under the curve per 20 min above basal in the presence of 27.7 mM glucose was 6,516 +/- 1,435 pg, which was not significantly different from the value of 4,772 +/- 866 pg obtained during arginine perifusion. However, the area under the curve during 20 min above basal obtained in the presence of linoleate and linolenic acid (8,712 +/- 1,949 and 10,506 +/- 1,490 pg, respectively) were significantly different (P less than 0.05) from those calculated during arginine and glucose perifusions. There was no statistically significant difference between the effects of these two fatty acids at the concentrations tested. In conclusion, our data suggest that linoleic acid and linolenic acid may be, at least in this murine islet preparation, as effective in stimulating insulin release as glucose and arginine, hitherto used to assess the abilities of nutrients to stimulate insulin secretion. However, it remains to be seen whether the efficacy of these polyunsaturated fatty acids in insulin release by murine islets will be obtained in experiments performed on human islets.

Animals↗
PubMed1992

Relative weight classifications in the assessment of underweight and overweight in the United States.

We compared five recent relative weight classifications based on body mass index for their estimates of prevalence of underweight and overweight in the adult population of the United States and for their ability to predict subsequent morbidity and mortality. The sources of the classifications were: the 1990 Dietary Guidelines for Americans of the US Departments of Agriculture and Health and Human Services, the National Academy of Sciences, the National Center for Health Statistics, the World Health Organization, and the Canadian Minister of National Health and Welfare. These classifications were applied to the body mass index distributions of the second National Health and Nutrition Examination Survey (1976-1980) and to the Hispanic Health and Nutrition Examination Survey (1982-1984). Depending on classification, a wide range of prevalence for the total population was found: 9-17% of the US population were categorized as underweight, and 25-45% were categorized as overweight. White women had the highest prevalence of underweight in all but the National Center for Health Statistics classification. Black and Mexican American women had the highest prevalence of overweight under all classifications (range: 38.4-58.6%). Associations with health outcomes were determined using all cause hospitalization and mortality in the 1971-1987 follow-up of the first National Health and Nutrition Examination Survey. Underweight and overweight as defined by the National Academy of Sciences classification had the highest population attributable risk for hospitalization and death: 5.0% of hospitalizations and 11.0% of deaths among men and 4.2% of hospitalizations and 11.4% of deaths among women were associated with weights outside the healthy range. Under this classification a greater proportion of both hospitalizations and mortality were associated with overweight than underweight. For all classifications, a higher proportion of hospitalizations were associated with overweight than underweight. All classifications performed better at predicting death than hospitalization.

Adult↗
PubMed1991

Report on the Fourth Conference for Federally Supported Human Nutrition Research Units and Centers.

The Fourth Conference for Federally Supported Human Nutrition Research Units and Centers, sponsored by the Interagency Committee on Human Nutrition Research, addressed two topics: nutrition and function, and nutrient interactions and toxicities. This article summarizes the conference's introductory remarks and the contents of the 34 papers presented. Future meetings of federally supported nutrition research units and centers will focus on other human nutrition research topics and will be held biennially.

Humans↗
PubMed1990

Enhancement of endocrine pancreatic secretions by essential fatty acids.

Recent studies have suggested the beneficial effects of essential fatty acids in postoperative patients receiving total parenteral nutrition. While there is abundant information on the role of glucose and amino acids on insulin release, the effect of essential fatty acids on endocrine pancreatic secretions is not clear. Since linoleic and linolenic acids are constituents of TPN solutions as well as dietary fat, our aim was to examine their effect on the endocrine pancreatic function, using isolated islets. In each experiment, six islets microdissected from three mice were preperifused at the rate of 1 ml/min with Krebs-Ringer bicarbonate (KRB) buffer pH 7.4 containing 2% bovine albumin and 5.5 mM glucose (basal) with continuous supply of 95%/5%, O2/CO2 for 1 hr, after which basal samples were collected on ice every minute. The perifusion was continued for 20 min after the addition of a mixture of 10 mM linoleic acid and 5 mM linolenic acid to the KRB. During each perifusion phase, effluent samples were also collected for insulin and glucagon assay. The mean integrated area under the curve/20 min showed an increase in both insulin and glucagon secretions with the addition of fatty acids. Hence insulin increased from a basal 3154.8 +/- 953.7 to 8393.0 +/- 2073.1 pg (P less than 0.025, n = 6) and glucagon increased from 193.7 +/- 46.9 to 1566.1 +/- 411.2 pg (P less than 0.0025, n = 5). The fatty-acid-induced insulin but not glucagon secretion was blocked by the addition of 2 mM palmoxirate an inhibitor of fatty acid oxidation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Changing dietary patterns.

Previously traditional dietary patterns in Japan are no longer typical. The current changing conditions provide an opportunity to examine more closely some important health conditions associated with the changed lifestyle and concentrations of dietary total fat and saturated fatty acid, and the ratio of n-3 to n-6 polyunsaturated fatty acids in the diet.

Diet↗
PubMed1988

Critical examination of therapeutic efficacy of a pH-sensitive enteric-coated pancreatic enzyme preparation in treatment of exocrine pancreatic insufficiency secondary to cystic fibrosis.

In an attempt to critically examine the therapeutic efficacy of pH-sensitive enteric-coated pancreatic enzyme preparations in patients with pancreatic insufficiency due to cystic fibrosis, postprandial duodenal concentration and recovery of orally administered pancreatic enzymes, duodenal pH, and coefficient of fat absorption were determined in eight cases after ingestion of equivalent dosage of enteric-coated as well as conventional enzyme preparations. Ingestion of a pH-sensitive enteric-coated pancreatic enzyme preparation was accompanied with a significant (P less than 0.05) reduction in steatorrhea, as well as a lower mean concentration and recovery of lipase and trypsin activity in the postprandial duodenal samples. Furthermore, the intraluminal duodenal pH was noted to be below 4.0 during the postprandial period in all patients. These data suggest that in cystic fibrosis, the greater therapeutic efficacy of pH-sensitive enteric-coated preparations over conventional preparations may be related to the protection of pancreatic enzymes from the highly acidic milieu in the duodenum, allowing for possible bioavailability in the distal small intestine.

Adult↗
PubMed1987

Absorption of safflower oil and structured lipid preparations in patients with cystic fibrosis.

Patients with cystic fibrosis (CF) and pancreatic insufficiency usually have decreased linoleic and increased oleic, palmitoleic and eicosatrienoic (20:3 omega 9) acids compared to normal values of blood and tissue lipids. These changes are consistent with early essential fatty acid deficiency and are observed despite the regular use of exogenous pancreatic enzyme supplementation. As part of a study to determine the relative role of malabsorption as the etiology for the altered fatty acid status, the change in total plasma fatty acids and in area percent of plasma linoleic acid was determined in CF patients and control subjects following the ingestion of various lipid supplements, including two safflower oil preparations and two structured lipid preparations. Fasting subjects consumed 36 g of lipid in a milkshake containing 15 g of protein and 45 g of carbohydrate. Plasma samples obtained 0, 2, 4, 6 and 8 hr after the meal showed that the CF patients absorbed all preparations when administered with their regular dose of pancreatic enzyme supplement. Comparison of the patterns of increase for total plasma fatty acids and area percent of plasma linoleic acid following the administration of the different lipid supplements in CF patients and control subjects suggests that malabsorption alone is not the cause of the abnormal fatty acid composition in the lipids of CF patients and that increased caloric intake along with consumption of adequate amounts of linoleic acid should improve the linoleic acid status of CF patients; there may be selectively increased metabolism of certain fatty acids from the ingested lipids in the relatively malnourished CF patient compared to control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Role of nonpancreatic lipolytic activity in exocrine pancreatic insufficiency.

Patients with exocrine pancreatic insufficiency may absorb greater than 50% of dietary fat despite the absence of measurable pancreatic lipase activity. Nonpancreatic lipolytic activity was measured in gastric and duodenal aspirates from 5 patients with exocrine pancreatic insufficiency secondary to alcoholism and in aspirates from 5 alcoholics without evidence of exocrine pancreatic dysfunction (controls). Samples were collected under fasting and postprandial conditions. All patients with exocrine pancreatic insufficiency had nonpancreatic lipolytic activity in gastric and duodenal aspirates. Lipolytic activity in gastric aspirates was not significantly different between the patients with exocrine pancreatic insufficiency and the controls during the fasting and postprandial periods. Pancreatic insufficiency was associated with significantly (p less than 0.05) higher nonpancreatic lipolytic activity in the duodenum under fasting conditions. No significant difference between the groups was found in postprandial nonpancreatic lipolytic activity. Nonpancreatic lipolytic activity accounted for approximately 90% of total lipolytic activity at the ligament of Treitz in patients with exocrine pancreatic insufficiency as opposed to 7% in the control subjects. These observations suggest a significant role for nonpancreatic lipolytic activity (lingual lipase and gastric lipase) in fat digestion in patients with pancreatic insufficiency secondary to chronic alcohol abuse.

Alcoholism↗