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Biomedical subjects

J R Hunt

Publications and source records attributed to J R Hunt.

At least 37 records · Page 2Linked to original sources
PubMed1997

Women's health initiative. Why now? What is it? What's new?

Studies collectively named the Women's Health Initiative (WHI) are currently enrolling 164,500 postmenopausal women in several overlapping clinical trials and an observational study. The overall goals of WHI are to understand the determinants of postmenopausal women's health and to evaluate the efficacy of practical interventions in preventing the major causes of morbidity and mortality in older women. This article reviews the research leading to the WHI studies; describes the study designs and protocols, with an emphasis on what's new about WHI from a psychological perspective; and outlines the major psychosocial hypotheses under investigation and the major challenges WHI presents to psychological science.

Aged↗
PubMed1997

Using a brief household food inventory as an environmental indicator of individual dietary practices.

OBJECTIVES: This study examined whether foods in household pantries are an indicator of house-hold members' diet. METHODS: In a random-digit-dial survey, the presence in the house of 15 high-fat foods was assessed with whoever answered the phone. A randomly selected household member was surveyed about diet-related behaviors (n = 1002). RESULTS: Individuals in the precontemplation stage of dietary change had more high-fat foods in their pantry than those in maintenance (means of 7.4 and 5.8, respectively). Individuals with low-fat pantries had an intake of 32% energy from fat vs 37% for those with high-fat pantries. CONCLUSIONS: Household food inventories are a practical and valid approach to monitoring dietary behaviors in community-based studies.

Adult↗
PubMed1996

A steady-state labelling approach to the measurement of proteoglycan turnover in vivo and its application to glomerular proteoglycans.

Rats were implanted with mini osmotic pumps delivering sodium [35S]sulphate and their newly synthesized proteoglycans were labelled over a 146 h period (steady-state labelling). Proteoglycan turnover was measured in vivo using a chase protocol. Glomerular proteoglycans were recovered quantitatively and the perlecan present was isolated by immunoprecipitation. The procedure allows newly synthesized proteoglycans to be quantified in mass units (pmol of glycossminoglycan sulphate) after labelling and during the chase. Ultrastructural-immunogold experiments identified the location of perlecan as the glomerular basement membrane and mesangial matrix. Perlecan in the basement membrane was quantified using the ultrastructural-immunogold technique. Perlecan comprises about 10% of the total glomerular proteoglycans, which are otherwise associated with glomerular cells and the mesangium. Both the total glomerular heparan sulphate proteoglycans and perlecan turn over rapidly (t1/2 approximately 3-4 h and < 3 h respectively). In contrast, turnover of proteoglycans in other tissues was slow, except in the liver where the heparan sulphate and chondroitin sulphate t1/2 values were 16 h and 9 h respectively. Microalbuminuria was induced with a low-dose regimen of puromycin aminonucleoside. At the onset of microalbuminuria (5 days) there was no change in the level of newly synthesized perlecan, or in perlecan in the glomerular basement membrane detected by immunogold labelling. Newly synthesized perlecan had undergone a minimal change in turnover rate by day 5 in puromycin aminonucleoside-treated rats. In contrast, the total glomerular proteoglycan population showed a dramatic decrease in turnover by day 5. Since there was no evidence of accumulation of glomerular proteoglycans on either day 5 or day 6, it is likely that decreased turnover of cell-associated proteoglycans is accompanied by an equivalent decrease in their synthesis.

Albuminuria↗
PubMed1996

Bioavailability algorithms in setting Recommended Dietary Allowances: lessons from iron, applications to zinc.

In addition to determining the amounts of isolated nutrients required for physiological function and homeostatic control, setting Recommended Dietary Allowances requires a consideration of nutrient bioavailability from foods in common diets. Bioavailability algorithms, or mathematical models to estimate nutrient bioavailability from different diets, have great appeal to help establish recommended intakes and identify beneficial dietary modifications. Accurate algorithms are difficult to develop because of the chemical complexity of the food supply and the numerous interactions that affect the bioavailability of mineral elements. A combination of reductionist and holistic approaches is necessary to identify the effects of isolated dietary components, and then to evaluate these effects in the complicated matrix of a whole diet. The most extensive development of bioavailability algorithms for mineral nutrients has been for iron, and understanding the strengths and weaknesses of the iron algorithms may help in development of algorithms for other inorganic nutrients such as zinc. Examples are provided to indicate the possible revision of iron bioavailability algorithms, the difficulty of verifying the iron bioavailability algorithms with iron status indices, and the possible development of zinc bioavailability algorithms. Bioavailability must be considered in the context of the biological control of mineral absorption, utilization and excretion, which may outweigh the importance of mineral bioavailability from diets in affluent countries with a varied and abundant food supply. While bioavailability algorithms may be helpful in estimating the effects of dietary changes or recommendations, and in improving diets of populations with a high incidence of deficiency of the mineral, they are not as yet sufficiently developed and validated for setting quantitative recommendations for "bioavailable" mineral intake.

Algorithms↗
PubMed1995

High- versus low-meat diets: effects on zinc absorption, iron status, and calcium, copper, iron, magnesium, manganese, nitrogen, phosphorus, and zinc balance in postmenopausal women.

The effects of three diets--high meat (HM), low meat (LM), or low meat with mineral supplements (LS)--on zinc absorption, elemental balance, and related clinical indexes were investigated in a metabolic study of 14 women aged 51-70 y. The women ate each of the three diets for 7 wk in random order. Lean beef, chicken, ham, and tuna in the HM diet replaced foods with a low mineral content in the LM diet. The LS diet was similar to the HM diet in K, P, Fe, Mg, and Zn contents. Compared with the other diets, the HM diet increased zinc absorption and retention, and slightly increased urinary zinc. Nitrogen and calcium balances and urinary calcium were not different for the HM and LM diets. Iron balance was not different for the HM and LS diets with similar iron content, but the HM diet was unexpectedly associated with lower iron status (higher iron-binding capacity and lower ferritin than LM and LS diets). These results indicate that 0.8 g protein/kg body wt meets protein requirements in older women, and that high meat consumption increases zinc retention without compromising calcium status and may reduce indexes of iron status, in contrast with iron absorption results from studies with radiolabeled test meals.

Absorption↗
PubMed1995

Coupling transport and biodegradation of VOCs in surface and subsurface soils.

Volatile organic chemicals present at Superfund sites preferentially partition into the soil gas and may be available for microbial degradation. A simple mass transfer model for biodegradation for volatile substrates has been developed for the aerobic decomposition of aromatic and aliphatic hydrocarbons. The mass transfer analysis calculates diffusive fluxes from soil gas through water and membrane films and into the cell. This model predicts an extreme sensitivity of potential biodegradation rates to the air-water partition coefficients of the compounds. Aromatic hydrocarbons are removed rapidly while the aliphatic hydrocarbons are much slower by orders of magnitude. Furthermore, oxygen transfer is likely to limit aromatic hydrocarbon degradation rates. The model presents results that cast doubt on the practicality of using methane or propane for the co-metabolic destruction of trichloroethylene in a gas phase bioreactor. Toluene as a primary substrate has better mass transfer characteristics to achieve more efficient trichloroethylene degradation. Hence, in sites where these contaminants coexist, bioremediation could be improved.

Biodegradation, Environmental↗
PubMed1995

Physician recommendations for dietary change: their prevalence and impact in a population-based sample.

A random-digit-dialing survey to examine the prevalence, content, and impact of physician dietary recommendations in a representative population-based sample of Washington State residents was administered to 1972 persons aged 18 years and older. Twenty percent of those surveyed received a physician's recommendation for dietary change in the previous year. The most common recommendations were to decrease intake of cholesterol, calories, and red meat and to increase intake of vegetables and fiber. Respondents receiving recommendations were more likely to report decreased use of high-fat foods and increased use of high-fiber foods and to be in the maintenance stage of dietary change. Results suggest that physicians can play a limited role in promoting dietary change.

Adolescent↗
PubMed1994

Severe or marginal iron deficiency affects spontaneous physical activity in rats.

The influence of dietary iron on spontaneous activity was investigated in growing rats. Male rats weighing 97 +/- 10 g fed diets containing 4.6 (deficient), 19.9 (marginal), and 108.4 (adequate) mg Fe/kg diet for 8 wks had hemoglobin values of 52 +/- 6, 152 +/- 4, and 159 +/- 6 g/L, and liver nonheme iron concentrations of 0.79 +/- 0.24, 1.36 +/- 0.39, and 4.58 +/- 0.62 mumol/g, respectively. Body weights were affected only at the lowest iron intake. Diurnal activity was not reversed by iron status; all animals were more active during the dark cycle than the light cycle. Iron deficiency resulted in less time and frequency of horizontal, vertical, and stereotypic movements; less distance moved; and less frequent rotations. Movement speed of iron-deficient rats was faster during early iron deficiency. In the light, rats with marginal iron nutriture were generally more active than were iron-deficient or iron-adequate animals. In the dark, activity generally decreased with each reduction in dietary iron.

Analysis of Variance↗
PubMed1994

Effect of ascorbic acid on apparent iron absorption by women with low iron stores.

The effect of ascorbic acid supplementation on apparent iron absorption was tested in women with low iron stores. For 10 wk, 25 healthy nonpregnant women, aged 20-45 y with low serum ferritin (3.5-17.7 micrograms/L), consumed either a diet with predicted poorly bioavailable iron or a typical Western diet, classified according to dietary meat and ascorbic acid contents. Meals were supplemented with ascorbic acid (500 mg, three times a day) for 5 of the 10 wk, in a double-blind, crossover design. Ascorbic acid did not affect most biochemical indexes of iron status, the biological half-life of 59Fe, or apparent iron absorption (diet-feces) from either diet, but slightly increased serum ferritin (11.9 vs 10.7 micrograms/L, P < 0.06) when data from both diets were combined. These results support other evidence that ascorbic acid has less effect on iron bioavailability than has been predicted from tests with single meals.

Adult↗
PubMed1992

Dietary protein, as egg albumen: effects on bone composition, zinc bioavailability and zinc requirements of rats, assessed by a modified broken-line model.

The effect of dietary protein concentration on zinc bioavailability, requirements and incorporation into bones was investigated in growing rats. Zinc requirements were determined by the broken-line method. Protein did not affect either absorption or biological half-life of 65Zn added to the diet. Zinc requirements based on weight gain or tibia zinc were generally greater when rats were fed 30% rather than 15% egg white. When fed 30% rather than 15% egg white, zinc-deficient rats gained less weight and tended to incorporate less zinc into bone, whereas zinc-adequate rats gained weight similarly and incorporated more zinc into bone. Dietary protein concentration apparently elevated the maximum amount of zinc incorporated into bones of rats fed adequate zinc. When dietary zinc was adequate (25 mg/kg diet), tibia zinc concentrations increased linearly with dietary concentrations of 15, 25, 35 and 45% egg white. When dietary zinc was adequate, higher protein diets resulted in lower tibia nitrogen, and higher tibia zinc, without substantial changes in tibia size or calcium concentration. These results indicate that high protein diets increase zinc requirements and bone zinc deposition, the latter being a consequence of altered bone zinc metabolism, rather than improved zinc bioavailability.

Administration, Oral↗
PubMed1991

Coping with health threat: social influence processes in reactions to medical test results.

In a laboratory experiment, undergraduate subjects tested positive for an enzyme deficiency they believed to be a risk factor for pancreatic disorders. All Ss were tested with a confederate who received a positive or negative test result. For half the Ss, the confederate expressed a minimizing appraisal of the deficiency's seriousness. Although Ss' concern about the test result was significantly reduced by what the confederate said, behavioral intentions were determined by the confederate's diagnostic status. The effect of the confederate's diagnostic status on intentions was mediated by Ss' perceptions of the deficiency's prevalence. The results support Leventhal's self-regulation theory and demonstrate that the opinions and health characteristics of comparison others have differential effects on cognitive, emotional, and behavioral aspects of coping with a health threat.

Adaptation, Psychological↗
PubMed1990

Ascorbic acid: effect on ongoing iron absorption and status in iron-depleted young women.

The effect of ascorbic acid on iron retention from a diet with predicted low iron bioavailability (containing minimal meat and ascorbic acid) was investigated in iron-depleted premenopausal women. Eleven women were depleted of storage iron (indicated by serum ferritin) through a combination of diet (5.0 mg Fe/2000 kcal for 67-88 d) and phlebotomy. They then consumed a diet containing 13.7 mg Fe/2000 kcal, supplemented with placebo or ascorbic acid three times daily (1500 mg total) with meals for 5.5 wk. Ascorbic acid improved apparent iron absorption (balance method) [38 +/- 2% (means +/- SEM) vs 27 +/- 2%]. Ascorbic acid also improved hemoglobin, erythrocyte protoporphyrins, and serum iron but not hematocrit, serum ferritin, iron-binding capacity, or transferrin saturation. In iron-depleted women consuming a diet with predicted poor iron availability, ascorbic acid supplementation enhanced body iron retention for 5.5 wk.

Adult↗
PubMed1990

The Planetree Model Hospital Project: an example of the patient as partner.

The Planetree Model Hospital Project at Pacific Presbyterian Medical Center in San Francisco uses a patient-centered philosophy to incorporate the patient as a partner in the care process. This article describes the Planetree unit and discusses two aspects of the program--training patients to be partners and increasing nurse satisfaction. Such programs have the potential for improving the health outcomes of patients and aiding hospitals by assuring quality of care with greater patient participation, by improving public relations, and by promoting staff satisfaction.

Hospital Bed Capacity, 100 to 299↗