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Biomedical subjects

K L Tucker

Publications and source records attributed to K L Tucker.

At least 19 recordsLinked to original sources
PubMed2006

Association of dietary and biochemical measures of vitamin K with quantitative ultrasound of the heel in men and women.

INTRODUCTION: Low vitamin K nutritional status is associated with increased fracture risk but is inconsistently related to bone mineral density (BMD), suggesting that vitamin K may affect components of bone strength not measured by BMD, such as microarchitecture. Quantitative ultrasound (QUS) may assess trabecular orientation, providing information on the mechanical properties of bone and may serve as a potential alternative to BMD for gaining insight to the relation between vitamin K and bone strength. We therefore examined the association of vitamin K nutritional status measured in several different ways with QUS in men and women who participated in the Framingham Osteoporosis Study. METHODS: From 1996 to 2001, broadband ultrasound attenuation (BUA) and speed of sound (SOS) of the calcaneus (heel) were measured in 583 men and 768 women (mean age 59 years). Vitamin K nutritional status was assessed between 1995 and 1998 by three separate measures: plasma phylloquinone concentration, serum percent undercarboxylated osteocalcin (%ucOC) and dietary vitamin K intake. Multiple linear regression analyses were used to calculate regression coefficients in order to evaluate the associations between both measures of QUS and each measure of vitamin K nutritional status. Regression analyses were conducted separately for subgroups of participants defined by gender, menopause status and current use of estrogen replacement medication. RESULTS: Among the men, plasma phylloquinone concentration was positively associated with both BUA (P<0.01) and SOS (P=0.02) of the heel. Neither serum %ucOC nor dietary vitamin K intake, however, was associated with QUS measures. Among women, none of the three measures of vitamin K nutritional status were associated with either BUA or SOS, regardless of menopause status or use of estrogen. Although QUS is associated with vitamin K nutritional status in men, the observed relation was not consistent among subgroups of participants. CONCLUSION: These findings suggest that QUS may not be the best method for elucidating the role of vitamin K on the skeleton.

Bone Density↗
PubMed2005

Benefits of fatty fish on dementia risk are stronger for those without APOE epsilon4.

OBJECTIVE: To compare associations of lean fish vs fatty fish (tuna or other fish) intake with dementia, Alzheimer disease (AD), and vascular dementia (VaD) and in relation to APOE epsilon4 status in the Cardiovascular Health Cognition Study (CHCS). METHODS: Fish intake was assessed by food frequency questionnaires. Incident dementia, AD, and VaD were determined through a series of cognitive tests, physician's assessment, and committee consensus. We used Cox proportional hazards regression to calculate hazard ratios of dementia, AD, and VaD with lean fried fish, fatty fish, or total fish intake, which were then stratified by the presence of APOE epsilon4. RESULTS: Although consumption of lean fried fish had no protective effect, consumption of fatty fish more than twice per week was associated with a reduction in risk of dementia by 28% (95% CI: 0.51 to 1.02), and AD by 41% (95% CI: 0.36 to 0.95) in comparison to those who ate fish less than once per month. Stratification by APOE epsilon4 showed this effect to be selective to those without the epsilon4 allele. Adjustment by education and income attenuated the effect. CONCLUSION: In the Cardiovascular Health Cognition Study, consumption of fatty fish was associated with a reduced risk of dementia and Alzheimer disease for those without the APOE epsilon4 allele.

Aged↗
PubMed2003

Relative influence of diet and physical activity on cardiovascular risk factors in urban Chinese adults.

OBJECTIVE: The relative influence of dietary factors vs physical activity on cardiovascular risk factors are poorly understood. We investigated these factors in a population whose traditional diet may have both positive (high plant-based) and negative (high refined carbohydrate) aspects, and whose physical activity levels (PALs) vary widely. DESIGN: Cross-sectional study. SUBJECTS: A total of 130 weight stable adults aged 35-49 y (BMI 18-35 kg/m(2)) living in urban Beijing, China. MEASUREMENTS: Dietary intake (by food frequency questionnaire), PAL as the ratio of predicted total to resting energy expenditure), percent body fat (by deuterium oxide dilution), and central adiposity (waist circumference and waist to hip ratio) were assessed. Biochemical parameters (total cholesterol, low- and high-density lipoprotein cholesterol (LDL-C; HDL-C), triglyceride (TG), apolipoproteins A-I and B, glucose, insulin, and homocysteine and its related vitamins), blood pressure and presence of the metabolic syndrome (having >/=3 risk factors of central adiposity, HDL-C, TG, glucose, blood pressure) were also examined. RESULTS: Mean values for cardiovascular risk factors were relatively low, but 19% of subjects had the metabolic syndrome. Using validated methods for measuring food intake and energy expenditure, we found that an adverse cardiovascular risk profile was associated with a diet high in carbohydrate, low in polyunsaturated fat, and low in fruit and vegetables, independent of body fatness and its distribution. While dietary factors predicted individual cardiovascular risk factors more consistently than PAL, avoidance of low PAL reduced the risk of having the metabolic syndrome. CONCLUSION: These results suggest that, regardless of total body fatness and fat distribution, multiple unfavorable dietary factors and low physical activity independently increase the risk for cardiovascular disease. Avoidance of a sedentary lifestyle additionally reduces the risk of developing the metabolic syndrome.

Adult↗
PubMed2002

Television and children's consumption patterns. A review of the literature.

The recent increase in childhood obesity has, among other things, focused attention on the role that television may play. This paper summarizes results of studies published in peer review journals since 1970 with data pertaining to the relationship between television use and children's food intake. Studies fall into four categories: content analyses; effects of television advertising on children's food behaviors; television and pediatric obesity, with effects on children's dietary intake and physical activity; and television use and children's food consumption patterns. Content analyses have shown that food is the most frequently advertised product category on children's TV. The majority of these ads target highly sweetened products, but more recently, the proportion from fast food meal promotions has been growing. Controlled studies on children's choices have consistently shown that children exposed to advertising choose advertised food products at significantly higher rates than do those not exposed. Purchase request studies have documented associations between number of hours of TV watched and number of requests from the child to the mother for specific food items, as well as the presence of those items in the home. Greater TV use has been associated with higher intakes of energy, fat, sweet and salty snacks, and carbonated beverages and lower intakes of fruit and vegetables. Several large studies have documented associations between number of hours of TV watched and both the prevalence and incidence of obesity. The combination of lifestyle factors that accompany heavy television use appear to place children at risk of obesity and poor nutritional status.

Adolescent↗
PubMed2002

Neurotrophins and the control of axonal outgrowth.

The neurotrophins NGF, BDNF, NT-3, and NT-4/5 are well known for their neuron survival-promoting functions. This review focuses upon a less-investigated function of this gene family, namely that of controlling the growth of axons in vivo. Recent evidence is discussed that reveals a definitive requirement for neurotrophin signaling in the elongation of peripheral nerves during embryonic development.

Animals↗
PubMed2001

In vivo imaging of the mammalian nervous system using fluorescent proteins.

The recent development of fluorescent proteins has rapidly and radically altered the way cell biology is performed by allowing simple, non-invasive imaging of cellular processes in real time. The special properties of the nervous system, such as synaptic morphology, axonal/dendritic maturation, and neuronal migration are especially amenable to investigation using fluorescent proteins. This review focuses on the various genetic and viral vectors used to express fluorescent proteins in vivo and in slice culture, and the strengths and limitations associated with them.

Animals↗
PubMed2001

The acid-base hypothesis: diet and bone in the Framingham Osteoporosis Study.

BACKGROUND: There continues to be considerable debate about the role of acid vs. basic components of the diet on the long-term status of bone mineral density. AIM: In a set of two analyses, we examined the effect of components in the diet thought to have basic effects (magnesium, potassium, fruit, vegetables) and acid effects (protein) on bone mineral density in an elderly cohort. METHODS: Bone mineral density of participants in the Framingham Osteoporosis Study was measured at three hip sites and one forearm site at two points in time, four years apart. At the time of baseline measurement, participants ranged in age from 69-97 years. Dietary intake was assessed at baseline by food frequency questionnaire. RESULTS: As hypothesized, magnesium, potassium, fruit and vegetable intakes were significantly associated with bone mineral density at baseline and among men, with lower bone loss over four years. In contrast to the hypothesis, higher rather than lower protein intakes were associated with lower bone loss. CONCLUSION: Together these results support the role of base forming foods and nutrients in bone maintenance. The role of protein appears to be complex and is probably dependent on the presence of other nutrients available in a mixed diet. A balanced diet with ample fruit and vegetables and adequate protein appears to be important to bone mineral density.

Acid-Base Equilibrium↗
PubMed2001

Methylated cytosine and the brain: a new base for neuroscience.

Methylation of genomic CpG residues is crucial for proper neuronal function. Rett syndrome, a common form of mental retardation, is associated with mutations in the gene encoding MeCP2, a methyl CpG binding protein linked to transcriptional repression. Gene knockouts of mouse Mecp2 have reproduced key aspects of the disease. A CNS-restricted knockout of Dnmt1, encoding the enzyme that maintains CpG methylation patterns, results in loss of mutant neurons and glia.

Animals↗
PubMed2001

Neurotrophins are required for nerve growth during development.

Although the requirement of neurotrophins for the prevention of cell death in the peripheral nervous system is well established, their physiological involvement in nerve growth is still unclear. To address this question, we generated a mouse that expresses the green fluorescent protein in post-mitotic neurons, allowing the repeated visualization of all motor and sensory axons during development. We imaged the growth of these axons into the limb bud of day 10.5 embryos. Sensory axons, but rarely motor axons, were targeted to ectopically placed beads containing any of the neurotrophins NGF, BDNF, NT-3 or NT-4/5. Conversely, a combination of function-blocking monoclonal antibodies to NGF, BDNF and NT-3 dramatically inhibited elongation of both sensory and motor axons in the limb bud, indicating that the growth of mixed nerves is dependent upon neurotrophins during development.

Animals↗
PubMed2001

Total and central obesity among elderly Hispanics and the association with Type 2 diabetes.

OBJECTIVE: To report the prevalence of total and central obesity in a representative sample of Puerto Rican and Dominican elders in Massachusetts, to compare them with a neighborhood-based group of non-Hispanic white elders, and to examine associations of obesity indices with the presence of type 2 diabetes. RESEARCH METHODS AND PROCEDURES: We examined the prevalence of overweight, obesity, and central obesity in 596 Hispanics of Caribbean origin, ages 60 to 92 years, and 239 non-Hispanic whites, and tested linear and logistic regression models to determine associations among body mass index (BMI), waist circumference (WC), and diabetes. RESULTS: Obesity (BMI > or = 30 kg/m(2)) was prevalent among all ethnic groups, ranging from 17% to 29% for Dominican and Puerto Rican men, respectively, and from 29% to 40% for non-Hispanic white and Dominican women, respectively. These differences were not statistically significant. Among Hispanic men and women, diabetes was prevalent across all BMI and WC categories but tended to be greatest among those with BMI of 25 to 29 kg/m(2) (41% to 43%). In contrast, diabetes was most prevalent in the obese group (36% to 45%) of non-Hispanic whites. Both BMI and WC were associated with the presence of diabetes, but the coefficients were greater for non-Hispanic whites than for Hispanics. DISCUSSION: Caribbean Hispanics and non-Hispanic whites living in the same Massachusetts localities had high prevalences of overweight and obesity. Total and central obesity exerted a differential effect on the presence of diabetes among ethnic groups; for Hispanics, diabetes was prevalent even among non-obese individuals, whereas for non-Hispanic white women, the prevalence of diabetes was strongly associated with total and central obesity. Additional research is needed to investigate the factors associated with the differential effect of obesity on the prevalence of type 2 diabetes among Hispanic and non-Hispanic white elders.

Adipose Tissue↗
PubMed2001

Evaluation of dietary quality in relationship to nutritional and lifestyle factors in elderly people of the US Framingham Heart Study and the European SENECA study.

OBJECTIVE: To evaluate dietary quality of European and American elderly subjects using different derivatives of dietary patterns (dietary scores and clusters) and to investigate the relationship of these approaches to nutritional and lifestyle factors. DESIGN: Data from the cross-sectional SENECA baseline study and Framingham Heart Study (original cohort and offspring) were used for data analysis. Food intake data were summarised into dietary clusters and into dietary scores (Healthy Diet Indicator and Mediterranean Diet Score). These measures of dietary quality were then tested for associations with lifestyle factors and measures of nutritional status. SUBJECTS/SETTING: The study population, aged 70-77 y, consisted of 828 subjects from Framingham, MA (USA) and 1282 subjects from the following European centres: Hamme, Belgium; Roskilde, Denmark; Padua, Italy; Culemborg, The Netherlands; Vila Franca de Xira, Portugal; Betanzos, Spain; and Yverdon, Burgdorf and Bellinzona, Switzerland. RESULTS: Dietary intake varied widely across the European and American research centres. In general, Southern European centres and Framingham had higher mean diet scores, indicating a higher dietary quality, than Northern European centres (MD-scores: 4.2-4.4 vs 2.7-3.5). Cluster analysis identified the following five dietary patterns characterised by: (1) sugar and sugar products; (2) fish and grain; (3) meat, eggs and fat; (4) milk and fruit; and (5) alcohol intake. The meat, eggs and fat pattern had significantly lower average dietary quality, as measured with all three diet scores than all other groups except the alcohol group. The fish and grain group had significantly better Mediterranean diet scores than all other groups. CONCLUSIONS: Dietary scores and dietary clusters are complementary measures to classify dietary quality. The associations with nutritional and lifestyle factors indicate the adequate categorisation into dietary quality groups. SPONSORSHIP: European Union, US Department of Agriculture, Agriculture Research Service, under agreement (58-1950-9-001), Haak Bastiaanse-Kuneman Foundation.

Aged↗
PubMed2001

The energy expenditure of postmenopausal women classified as restrained or unrestrained eaters.

OBJECTIVE: Restrained eating is a common dietary practice among individuals who are attempting to prevent weight gain, but little is known about differences in energy physiology and regulation between restrained and unrestrained eaters. We investigated this issue in non-obese free-living postmenopausal women classified as long-term restrained (n=26) or unrestrained (n=34) eaters group matched for body mass index (BMI). MEASUREMENTS: Measurements were made of total energy expenditure (TEE), resting energy expenditure (REE), body composition, reported leisure time activity, maximal aerobic capacity (VO2max) and weight change during the study period. In addition, physical activity level (PAL) and nonexercise activity thermogenesis (NEAT) were calculated from measured variables. RESULTS: There were no significant differences between the groups in body composition, weight change, aerobic capacity or total leisure time activity. Relationships between fat-free mass (FFM) and both REE and TEE, and the relationship between work load and energy expenditure in the test of maximal oxygen consumption, were also not different between groups. However, restrained eaters had a significantly lower PAL (equal to TEE/REE, 1.72+/-0.04 vs 1.84+/-0.04, P<0.05). In addition, in multiple regression models predicting NEAT, NEAT was significantly lower in restrained eaters than unrestrained eaters and there was a positive relationship between NEAT and weight change in unrestrained eaters but no relationship in restrained eaters (P<0.05). CONCLUSIONS: In contrast to a previous report, we found no significant difference in TEE between restrained and unrestrained eaters. PAL was slightly lower in restrained eaters, apparently due to reduced NEAT, and restrained eaters also lacked the positive association between NEAT and body weight change seen in unrestrained eaters. This latter finding, if confirmed in future studies, could help explain an increased susceptibility of restrained eaters to weight gain. SPONSORSHIP: NIH grants AG12829, DK46124 and T32AG00209, and US Cooperative Agreement number 58-1950-9-001.

Basal Metabolism↗
PubMed2001

Iron status of the free-living, elderly Framingham Heart Study cohort: an iron-replete population with a high prevalence of elevated iron stores.

BACKGROUND: Although iron deficiency occurs commonly in vulnerable groups of women of reproductive age, infants, and children, less is known about the iron nutriture of the elderly. OBJECTIVE: Our objective was to evaluate the iron status of a noninstitutionalized, elderly US population, with a particular focus on 2 concerns unique to the elderly: 1) potential confounding effects of chronic disease on iron measures and 2) increased occurrence of elevated iron stores. DESIGN: Multiple iron measures, including serum ferritin (SF), transferrin saturation, mean cell volume, and hemoglobin, were used to evaluate the prevalence of iron deficiency (ID), iron deficiency anemia (IDA), and other measures of iron nutriture in 1016 elderly white Americans aged 67-96 y from the Framingham Heart Study. "Diseased" subjects were defined as those with possible pathologically altered iron measures due to inflammation, infection, elevated liver enzymes, hereditary hemochromatosis, or cancer. The effect of altered iron status on various prevalence estimates was assessed. RESULTS: The elderly subjects had a low prevalence of ID (2.7%), IDA (1.2%), and depleted iron stores (3%; SF < 12 microg/L). In contrast, 12.9% had elevated iron stores (SF > 300 microg/L in men and SF > 200 microg/L in women), of which only 1% was attributable to chronic disease. The prevalence of ID, IDA, and depleted iron stores was unaffected by the presence of chronic disease. CONCLUSIONS: The Framingham Heart Study cohort is an iron-replete elderly population with a high prevalence of elevated iron stores in contrast with a low prevalence of iron deficiency, with insignificant effects of chronic disease on these iron status estimates. The likely liability in iron nutriture in free-living, elderly white Americans eating a Western diet is high iron stores, not iron deficiency.

Aged↗
PubMed2001

Nutrition and aging in developing countries.

The number of individuals aged 60 y or older is projected to double as a proportion of the world's population and to more than triple in number over the next 50 y. These changes will be most dramatic in the less developed countries, where the transition from a young to old age structure will be more compressed in time than it has been for developed countries. At the same time, there is evidence of a characteristic sequence of changes in diet and declines in physical activity associated with social and economic change. Diets are becoming higher in fats, animal products, and refined foods and lower in fiber, contributing to rapidly increasing prevalences of obesity and type 2 diabetes. The number of people with diabetes in developing countries is projected to almost triple by the year 2025. Hypertension and vascular disease are also rapidly becoming more prevalent. Evidence that lower birth weights are associated with greater likelihood of adult obesity and chronic disease underscores the magnitude of risk in these countries. Few programs or institutions currently exist to address the problems of the growing elderly population. The social changes that accompany urbanization will likely increase nutritional risk for this group. Despite lower energy intakes with age, elderly have higher requirements for several micronutrients, making them vulnerable to deficiencies that further aggravate chronic conditions. To reduce the impending burden of disease and disability worldwide, urgent action is needed to understand and to address the nutritional needs of the aging population.

Aging↗
PubMed2001

Eat a variety of healthful foods: old advice with new support.

Although dietary guidelines have long advised eating a variety of foods, most nutrition research has focused on specific nutrients and their relationships to health and disease. The recent failure of several randomized trials to confirm results of observational studies linking specific nutrients to disease outcomes, and a growing understanding of the beneficial phytochemicals in the natural food supply, has redirected attention to the complexity and importance of the foods themselves. Studies identifying associations between diet quality and mortality are beginning to quantify the importance of eating a variety of healthful foods and are helping to refine that advice.

Diet↗
PubMed2001

Relationships between use of television during meals and children's food consumption patterns.

OBJECTIVE: We examined relationships between the presence of television during meals and children's food consumption patterns to test whether children's overall food consumption patterns, including foods not normally advertised, vary systematically with the extent to which television is part of normal mealtime routines. METHODS: Ninety-one parent-child pairs from suburbs adjacent to Washington, DC, recruited via advertisements and word of mouth, participated. Children were in the fourth, fifth, or sixth grades. Socioeconomic data and information on television use were collected during survey interviews. Three nonconsecutive 24-hour dietary recalls, conducted with each child, were used to construct nutrient and food intake outcome variables. Independent sample t tests were used to compare mean food and nutrient intakes of children from families in which the television was usually on during 2 or more meals (n = 41) to those of children from families in which the television was either never on or only on during one meal (n = 50). Multiple linear regression models, controlling for socioeconomic factors and other covariates, were used to test strength of associations between television and children's consumption of food groups and nutrients. RESULTS: Children from families with high television use derived, on average, 6% more of their total daily energy intake from meats; 5% more from pizza, salty snacks, and soda; and nearly 5% less of their energy intake from fruits, vegetables, and juices than did children from families with low television use. Associations between television and children's consumption of food groups remained statistically significant in multiple linear regression models that controlled for socioeconomic factors and other covariates. Children from high television families derived less of their total energy from carbohydrate and consumed twice as much caffeine as children from low television families. There continued to be a significant association between television and children's consumption of caffeine when these relationships were tested in multiple linear regression models. CONCLUSION: The dietary patterns of children from families in which television viewing is a normal part of meal routines may include fewer fruits and vegetables and more pizzas, snack foods, and sodas than the dietary patterns of children from families in which television viewing and eating are separate activities.

Adult↗