Biomedical subjects

K L Tucker

Publications and source records attributed to K L Tucker.

At least 37 records · Page 2Linked to original sources

PubMed2000

Intake and food sources of macronutrients among older Hispanic adults: association with ethnicity, acculturation, and length of residence in the United States.

OBJECTIVE: To describe the food intake and food sources of macronutrients in diets of older Hispanic adults in the Northeastern United States and to explore relationships between acculturation, years in the United States, and macronutrient intake. DESIGN: Cross-sectional study using a representative sample of older Hispanic adults and a comparison group of non-Hispanic whites. SUBJECTS/SETTING: Hispanic (n = 711) and non-Hispanic white (n = 226) persons, aged 60 years and older, residing in Massachusetts. STATISTICAL ANALYSIS: Macronutrient intakes, collected by 24-hour dietary recall, were compared across ethnic groups by means of the general linear models procedure (with Bonferroni adjustments). Associations between macronutrient intake and predictor variables were tested with Pearson correlations and linear regression. The contribution of foods to total intake of macronutrients was determined by use of a rank procedure. RESULTS: Hispanic elderly subjects consumed significantly less saturated fat and simple sugars and more complex carbohydrates than did non-Hispanic whites. Hispanics residing in the United States for a longer time tended to have macronutrient profiles more similar to those of the non-Hispanic whites. Rice for Hispanic and bread for non-Hispanics were the major contributors of energy. More acculturated Hispanic elders consumed fewer ethnic foods and more foods related to the non-Hispanic-white eating patterns than those less acculturated. APPLICATIONS/CONCLUSIONS: Efforts to promote better diets among Hispanic elders need to emphasize maintenance or adoption of healthful dietary patterns based on ethnic and modern foods that will satisfy their biological, emotional, and social needs. Dietitians and other dietetics practitioners can use the information presented here in studying nutrition-related chronic diseases, in public health planning, and in nutrition education and promotion efforts directed to ethnic-specific, elderly Hispanic groups.

Acculturation↗

PubMed2000

Changes in patterns of fatness in adult men in relation to serum indices of cardiovascular risk: the Normative Aging Study.

BACKGROUND: Overweight and/or excessive weight gain, as well as changes in central fat deposition, have been implicated in increased incidence of coronary disease and type 2 diabetes. OBJECTIVE: We related adiposity (BMI, kg/m2, and waist circumference, WC, cm) to biochemical risk factors (cholesterol, triglyceride and glucose concentrations) for cardiovascular disease and diabetes. DESIGN: Associations were examined both cross-sectionally and longitudinally, among 867 men enrolled in the Normative Aging Study (NAS). We included all participants with complete anthropometric and clinical data at both enrollment (average age 45 y) and after approximately 15 y of follow-up (average age 60 y). We used multiple linear regression analysis to test relationships between body fatness and change in body fatness and the biochemical indices. RESULTS: In adulthood, concurrent BMI and waist circumference related significantly to triglyceride and glucose concentrations and to 2 h glucose responses at two time points. Measures of fatness 15 y earlier were also predictive of later triglyceride and glucose measures. When included together, BMI, but not WC, remained independently associated with triglycerides at both time points, while WC, but not BMI, remained significantly associated with fasting glucose concentrations and glucose response at the follow-up observation. In contrast, gains in weight and abdominal fat from entry to follow-up related more strongly to serum cholesterol concentrations than did concurrent measures. CONCLUSION: Attained weight, weight gain, and location of weight contribute differentially to these indices of cardiovascular and diabetes risk.

Adult↗

PubMed2000

Plasma vitamin B-12 concentrations relate to intake source in the Framingham Offspring study.

BACKGROUND: Low vitamin B-12 status is prevalent among the elderly, but few studies have examined the association between vitamin B-12 status and intake. OBJECTIVE: We hypothesized that vitamin B-12 concentrations vary according to intake source. DESIGN: Plasma concentrations and dietary intakes were assessed cross-sectionally for 2999 subjects in the Framingham Offspring Study. The prevalence of vitamin B-12 concentrations <148, 185, and 258 pmol/L was examined by age group (26-49, 50-64, and 65-83 y), supplement use, and the following food intake sources: fortified breakfast cereal, dairy products, and meat. RESULTS: Thirty-nine percent of subjects had plasma vitamin B-12 concentrations <258 pmol/L, 17% had concentrations <185 pmol/L, and 9% had concentrations <148 pmol/L, with little difference between age groups. Supplement users were significantly less likely than non-supplement-users to have concentrations <185 pmol/L (8% compared with 20%, respectively). Among non-supplement-users, there were significant differences between those who consumed fortified cereal >4 times/wk (12%) and those who consumed no fortified cereal (23%) and between those in the highest and those in the lowest tertile of dairy intake (13% compared with 24%, respectively), but no significant differences by meat tertile. Regression of plasma vitamin B-12 on log of intake, by source, yielded significant slopes for each contributor adjusted for the others. For the total group, b = 40.6 for vitamin B-12 from vitamin supplements. Among non-supplement-users, b = 56.4 for dairy products, 35.2 for cereal, and 16.7 for meat. Only the meat slope differed significantly from the others. CONCLUSIONS: In contrast with previous reports, plasma vitamin B-12 concentrations were associated with vitamin B-12 intake. Use of supplements, fortified cereal, and milk appears to protect against lower concentrations. Further research is needed to investigate possible differences in bioavailability.

Adult↗

PubMed2000

Psychological measures of eating behavior and the accuracy of 3 common dietary assessment methods in healthy postmenopausal women.

BACKGROUND: Factors affecting the accuracy of reported energy intake (rEI) need to be identified. OBJECTIVE: Our objective was to investigate the association of psychological measures of eating behavior with the accuracy of rEI assessed by 7-d weighed intakes, a 24-h recall, and a food-frequency questionnaire. DESIGN: Subjects were 26 restrained eaters aged 60.3 +/- 0.6 y (mean +/- SEM) and weighing 63.8 +/- 1.7 kg and 34 unrestrained eaters aged 59.4 +/- 0.6 y and weighing 64.0 kg. rEI was assessed by using 3 dietary assessment methods and total energy expenditure (TEE) was determined by using doubly labeled water. Calculated EI (cEI) was determined as TEE corrected for the estimated change in body energy. Subjects completed the Eating Inventory. RESULTS: rEI values were significantly lower than TEE values for all 3 dietary assessment methods (P < 0.05); there was no significant relation between rEI and TEE by any method. There was no significant difference in 100 x rEI:TEE between restrained and unrestrained eaters by any of the dietary assessment methods. When combined data from the 3 methods were used, 100 x rEI:cEI was not significantly different from 100% in unrestrained eaters (99 +/- 6.8%) but was lower in restrained eaters (89.1 +/- 5.3%; P < 0.05). There was a positive relation between hunger and 100 x rEI:TEE (P < 0.05). CONCLUSIONS: Low hunger is associated with undereating relative to normal eating during measurement of dietary intake; high dietary restraint may be associated with a reduction in reporting of consumed foods. Dietary hunger and restraint assessed with use of the Eating Inventory may help to identify subjects likely to underreport dietary intake.

Body Weight↗

PubMed2000

Dietary vitamin K intakes are associated with hip fracture but not with bone mineral density in elderly men and women.

BACKGROUND: Vitamin K has been associated with bone mineral density (BMD) and risk of hip fracture. The apolipoprotein (apo) E4 allele (APOE*E4) has been associated with bone fracture through a putative effect on vitamin K transport in blood. OBJECTIVE: The objective was to determine the associations between vitamin K intake, apo E genotype, BMD, and hip fracture in a population-based cohort of elderly men and women. DESIGN: Dietary vitamin K intake was assessed with a food-frequency questionnaire in 335 men and 553 women (average age: 75.2 y) participating in the Framingham Heart Study in 1988-1989. Incidence of hip fractures was recorded from 1988 to 1995. BMD at the hip, spine, and arm was assessed on 2 separate occasions (1988-1989 and 1992-1993). Comparisons between apo E genotype and BMD were made relative to E4 allele status (at least 1 epsilon4 allele compared with no epsilon4 allele). RESULTS: Individuals in the highest quartile of vitamin K intake (median: 254 microg/d) had a significantly lower fully adjusted relative risk (0.35; 95% CI: 0. 13, 0.94) of hip fracture than did those in the lowest quartile of intake (median: 56 microg/d). There were no associations between vitamin K intake and BMD in either men or women. No association was found between the E4 allele and BMD, and there were no significant interactions between the E4 allele and phylloquinone intake and BMD or hip fracture. CONCLUSIONS: Low vitamin K intakes were associated with an increased incidence of hip fractures in this cohort of elderly men and women. Neither low vitamin K intake nor E4 allele status was associated with low BMD.

Absorptiometry, Photon↗

PubMed2000

Protein nutritional status and function are associated with type 2 diabetes in Hispanic elders.

BACKGROUND: Hispanic elders have a high prevalence of diabetes and poor glycemic control, leading to inadequate nutritional status, muscle wasting, and impaired function. OBJECTIVE: We examined the association of type 2 diabetes with nutritional status measured by serum albumin concentrations and midupper arm muscle area (MAM) and with function measured by difficulty with at least one activity of daily living. DESIGN: : Health history and disability were assessed by self report in 556 Hispanics with a mean (+/- SD) age of 69 +/- 7 y and 158 non-Hispanic whites (NHW; aged 71 +/- 7 y) from the Massachusetts Hispanic Elders Survey. Energy intake (in MJ/d) and protein intake (in g/d) were estimated with use of a food-frequency questionnaire. Body mass index (BMI; in kg/m(2)) and C-reactive protein concentrations (in mg/L) were also measured. Multiple logistic regression models by ethnic group were used. RESULTS: There were no significant differences between Hispanics and NHWs in the proportion of those with low albumin concentrations or low MAM. Hispanic diabetic women had the lowest proportion of low MAM. The risk of low serum albumin concentration was twice as high in Hispanics taking insulin as in their NHW counterparts. Among Hispanics, low albumin concentration and low BMI were associated with low MAM; female sex, low albumin concentration, high BMI, and insulin use were significantly associated with risk of functional impairment. CONCLUSION: Type 2 diabetes is associated with poor nutritional status, muscle loss, and functional impairment among Hispanic elders.

Activities of Daily Living↗

PubMed2000

Why are nutritionally stunted children at increased risk of obesity? Studies of metabolic rate and fat oxidation in shantytown children from São Paulo, Brazil.

BACKGROUND: Previous research suggested that nutritionally stunted children may have increased risk of obesity, but little is known about potential underlying mechanisms. OBJECTIVE: We sought to test the hypothesis that stunted children have a low metabolic rate and impaired fat oxidation relative to nonstunted children. DESIGN: The subjects were 58 prepubertal boys and girls aged 8-11 y from the shantytowns of São Paulo, Brazil. Twenty-eight were stunted (height-for-age z score <-1.5) and 30 had similar weight-for-height but normal height (height-for-age z score >-1.5). Parents of children in the 2 groups had equivalent height and body mass index values. Fasting and postprandial energy expenditure, respiratory quotient (RQ), and substrate oxidation were measured with indirect calorimetry in a 3-d resident study in which all food was provided and body composition was measured with dual-energy X-ray absorptiometry. RESULTS: Stunted children had normal resting energy expenditure relative to body composition compared with control children (4559 +/- 90 and 4755 +/- 86 kJ/d, respectively; P: = 0.14) and had normal postprandial thermogenesis (2.4 +/- 0.3% and 2.0 +/- 0.3% of meal load, respectively; P: = 0.42). However, fasting RQ was significantly higher in the stunted group (0.92 +/- 0.009 compared with 0.89 +/- 0.007; P: = 0.04) and consequently, fasting fat oxidation was significantly lower (25 +/- 2% compared with 34 +/- 2% of energy expenditure; P: < 0.01). CONCLUSIONS: Childhood nutritional stunting is associated with impaired fat oxidation, a factor that predicted obesity in other at-risk populations. This finding may help explain recent increases in body fatness and the prevalence of obesity among stunted adults and adolescents in developing countries.

Body Composition↗

PubMed2000

Energy expenditure of stunted and nonstunted boys and girls living in the shantytowns of São Paulo, Brazil.

BACKGROUND: Stunting increases the risk of obesity in developing countries, particularly in girls and women, but the underlying reason is not known. OBJECTIVE: Our objective was to test the hypothesis that stunted children have lower energy expenditure than do nonstunted children, a factor that has predicted an increased risk of obesity in other high-risk populations. DESIGN: A cross-sectional study was conducted in shantytown children from São Paulo, Brazil. Twenty-eight stunted children aged 8-11 y were compared with 30 nonstunted children with similar weight-for-height. Free-living total energy expenditure (TEE) was measured over 7 d by using the doubly labeled water method. In addition, resting energy expenditure (REE) was measured by indirect calorimetry and body composition was measured by dual-energy X-ray absorptiometry. RESULTS: There were no significant associations between stunting and any measured energy expenditure parameter, including REE adjusted for weight (f1.gif" BORDER="0"> +/- SEM: 4575 +/- 95 compared with 4742 +/- 91 kJ/d, in stunted and nonstunted children, respectively) and TEE adjusted for weight (8424 +/- 239 compared with 8009 +/- 221 kJ/d, in stunted and nonstunted children, respectively). In multiple regression models that included fat-free mass and fat mass, girls had significantly lower TEE than did boys (P: < 0.05) but not significantly lower REE (P: = 0.17). CONCLUSIONS: There was no association between stunting and energy expenditure after differences between groups in body size and composition were accounted for. However, the girls had lower TEE than did boys, which may help to explain the particularly high risk of obesity in stunted adolescent girls and women in urban areas of developing countries.

Absorptiometry, Photon↗

PubMed2000

Self-reported prevalence and health correlates of functional limitation among Massachusetts elderly Puerto Ricans, Dominicans, and non-Hispanic white neighborhood comparison group.

BACKGROUND: Limited data suggest that Puerto Ricans experience greater disability than other ethnic groups, but few studies have examined the factors associated with this apparent difference. METHODS: We describe the prevalence of functional limitation and disability in a representative sample of Puerto Rican and Dominican elders in Massachusetts, and in a neighborhood comparison group of non-Hispanic whites (NHWs). We then relate disability scores, based on both prevalence and severity of ADL or IADL limitation, with self-reported history of diagnosed health conditions--adjusting for age, sex, body mass index (BMI; weight kg/height m(2)), income, education, living alone, smoking, and alcohol use. RESULTS: Seventy-five percent of Dominican women and 73% of Puerto Rican women reported difficulty with at least one ADL, compared with 64% of NHW women. Puerto Rican men reported significantly more limitation than did NHW or Dominican men. Conditions significantly associated with at least two disability measures among the NHW included smoking, former heavy alcohol use, arthritis, cataract, respiratory disease, and high BMI, but not stroke, diabetes, history of heart attack, or depression. The patterns for Puerto Ricans differed, with the strongest associations between disability and stroke, arthritis, diabetes, and depression, followed by history of heart attack, high BMI, cataract, poverty status, and respiratory disease. Only arthritis and depression were consistently significantly associated with disability among this smaller sample of Dominican elders. CONCLUSIONS: Functional limitation and disability are more prevalent among Puerto Ricans and among Dominican women than among neighborhood NHWs in Massachusetts. Greater disability is associated with the presence of chronic health conditions, which differ by ethnic group. Additional research is needed to further define the social and health factors that contribute to these ethnic differences.

Activities of Daily Living↗

PubMed2000

Prevalence and correlates of depressive symptoms among Hispanic elders in Massachusetts.

BACKGROUND: Few studies have addressed depression among Puerto Rican and Dominican elders. This study examined the prevalence of depressive symptomatology and associated situational factors, among a representative sample of Hispanic elders in the state of Massachusetts and a neighborhood comparison group of non-Hispanic whites (NHWs). METHODS: Participants included 715 Hispanic elders (429 Puerto Rican, 128 Dominican, and 149 other Hispanic) in Massachusetts and 238 NHW elders living in the same neighborhoods. Depressive symptomatology was measured with the Center for Epidemiologic Studies Depression Scale (CES-D). The associations between socioeconomic status, household arrangements, acculturation, health problems, and depression score were examined with multiple linear and logistic regression. RESULTS: Puerto Rican and Dominican elders had significantly greater prevalences of high depression scores when compared with neighborhood NHWs. After controlling for various social, demographic, and health characteristics, the scores of Puerto Ricans remained significantly greater than those of the NHWs, but not "Other Hispanic" groups. Higher CES-D scores were significantly associated with being female, living alone, and having a higher number of health problems, but not with income. Effects of acculturation were only found among Dominican elders. CONCLUSIONS: Puerto Rican elders experience high rates of depressive symptomatology that are associated with, but not fully explained by, high numbers of chronic health conditions. Further investigation is needed to both understand and treat this prevalent problem.

Acculturation↗

PubMed2000

Regulation of energy intake may be impaired in nutritionally stunted children from the shantytowns of São Paulo, Brazil.

We tested the hypothesis that nutritionally stunted children have impaired regulation of energy intake (EI), a factor that could help explain the increased risk of obesity associated with stunting in developing countries. A 3-d residency study was conducted in 56 prepubertal boys and girls aged 8-11 y from the shantytowns of Sao Paulo, Brazil. Twenty-seven of the subjects were stunted and 29 were not stunted; weight-for-height Z-scores were not significantly different between the groups. Parents of the two groups had equivalent heights and body mass indices. Measurements were made of voluntary EI from a self-selection menu, resting energy expenditure (REE) and body composition. In addition, a 753-kJ yogurt supplement was administered at breakfast on one study day (with an equal number of children receiving the supplement on each of the 3 study days) and its effect on daily EI assessed. There was no change in EI over time in either group (P: = 0.957), and no significant difference in EI between stunted and nonstunted children, even though the stunted children weighed 10% less. Energy intake per kilogram body weight was significantly higher in the stunted children (278 +/- 89 (SD), vs. 333 +/- 67 kJ/kg, P: < 0.05) and EI/REE was also significantly higher (1.91 +/- 0.34 vs. 1.68 +/- 0.38, P: < 0.05). However, the relationship between EI and body weight was not significantly influenced by stunting (P: = 0.12). There was no significant effect of the breakfast supplement on daily EI in either group although the absolute difference in EI between supplement and control days was greater in stunted than in nonstunted children (DeltaEI: +460 +/- 1574 vs. -103 +/- 1916 kJ/d, P: = 0.25). These data provide preliminary evidence consistent with the suggestion that stunted children tend to overeat opportunistically, but further studies are required to confirm these results in a larger study.

Basal Metabolism↗

PubMed2000

Effect of dietary protein on bone loss in elderly men and women: the Framingham Osteoporosis Study.

Few studies have evaluated protein intake and bone loss in elders. Excess protein may be associated with negative calcium balance, whereas low protein intake has been associated with fracture. We examined the relation between baseline dietary protein and subsequent 4-year change in bone mineral density (BMD) for 391 women and 224 men from the population-based Framingham Osteoporosis Study. BMD (g/cm2) was assessed in 1988-1989 and in 1992-1993 at the femur, spine, and radius. Usual dietary protein intake was determined using a semiquantitative food frequency questionnaire (FFQ) and expressed as percent of energy from protein intake. BMD loss over 4 years was regressed on percent protein intake, simultaneously adjusting for other baseline factors: age, weight, height, weight change, total energy intake, smoking, alcohol intake, caffeine, physical activity, calcium intake, and, for women, current estrogen use. Effects of animal protein on bone loss also were examined. Mean age at baseline (+/-SD) of 615 participants was 75 years (+/-4.4; range, 68-91 years). Mean protein intake was 68 g/day (+/-24.0; range, 14-175 g/day), and mean percent of energy from protein was 16% (+/-3.4; range, 7-30%). Proportional protein intakes were similar for men and women. Lower protein intake was significantly related to bone loss at femoral and spine sites (p < or = 0.04) with effects similar to 10 lb of weight. Persons in the lowest quartile of protein intake showed the greatest bone loss. Similar to the overall protein effect, lower percent animal protein also was significantly related to bone loss at femoral and spine BMD sites (all p < 0.01) but not the radial shaft (p = 0.23). Even after controlling for known confounders including weight loss, women and men with relatively lower protein intake had increased bone loss, suggesting that protein intake is important in maintaining bone or minimizing bone loss in elderly persons. Further, higher intake of animal protein does not appear to affect the skeleton adversely in this elderly population.

Absorptiometry, Photon↗

PubMed2000

Risk factors for longitudinal bone loss in elderly men and women: the Framingham Osteoporosis Study.

Few studies have evaluated risk factors for bone loss in elderly women and men. Thus, we examined risk factors for 4-year longitudinal change in bone mineral density (BMD) at the hip, radius, and spine in elders. Eight hundred elderly women and men from the population-based Framingham Osteoporosis Study had BMD assessed in 1988-1989 and again in 1992-1993. BMD was measured at femoral neck, trochanter, Ward's area, radial shaft, ultradistal radius, and lumbar spine using Lunar densitometers. We examined the relation of the following factors at baseline to percent BMD loss: age, weight, change in weight, height, smoking, caffeine, alcohol use, physical activity, serum 25-OH vitamin D, calcium intake, and current estrogen replacement in women. Multivariate regression analyses were conducted with simultaneous adjustment for all variables. Mean age at baseline was 74 years +/-4.5 years (range, 67-90 years). Average 4-year BMD loss for women (range, 3.4-4.8%) was greater than the loss for men (range, 0.2-3.6%) at all sites; however, BMD fell with age in both elderly women and elderly men. For women, lower baseline weight, weight loss in interim, and greater alcohol use were associated with BMD loss. Women who gained weight during the interim gained BMD or had little change in BMD. For women, current estrogen users had less bone loss than nonusers; at the femoral neck, nonusers lost up to 2.7% more BMD. For men, lower baseline weight and weight loss also were associated with BMD loss. Men who smoked cigarettes at baseline lost more BMD at the trochanter site. Surprisingly, bone loss was not affected by caffeine, physical activity, serum 25-OH vitamin D, or calcium intake. Risk factors consistently associated with bone loss in elders include female sex, thinness, and weight loss, while weight gain appears to protect against bone loss for both men and women. This population-based study suggests that current estrogen use may help to maintain bone in women, whereas current smoking was associated with bone loss in men. Even in the elderly years, potentially modifiable risk factors, such as weight, estrogen use, and cigarette smoking are important components of bone health.

Adult↗

PubMed2000

Type 2 diabetes is prevalent and poorly controlled among Hispanic elders of Caribbean origin.

OBJECTIVES: We estimated prevalence and control of type 2 diabetes in Puerto Rican, Dominican, and non-Hispanic White (NHW) elders and associated them with sociodemographic and health behavior variables and with body mass index (BMI) and waist circumference. METHODS: We used a cross-sectional analysis with a sample of Hispanic elders in Massachusetts and a comparison group of NHWs (1991-1997). The analysis included 379 Puerto Ricans, 113 Dominicans, and 164 NHWs, aged 60 to 96 years, with complete questionnaires and blood samples. RESULTS: Type 2 diabetes was significantly more prevalent among Puerto Ricans (38%) and Dominicans (35%) than among NHWs (23%). Differences remained after covariates were adjusted for. Hispanics with diabetes were approximately 3 times more likely to use insulin than NHWs. Puerto Ricans were 2 times, and Dominicans 3 times, more likely to have glycosylated hemoglobin concentrations of 7% or above than NHWs. BMI and waist circumference were individually associated with diabetes. When included in the model together, waist circumference, but not BMI, remained independently associated with diabetes. CONCLUSIONS: Ethnicity was more strongly associated with diabetes status and control than were socioeconomic or measured health behavior variables, suggesting that genetic or other culturally related factors may explain these differences.

Aged↗

PubMed2000

[Use of knee height to correct the body height of elderly Hispanics].

Loss of stature in certain elderly subjects can be attributed to diseases such as osteoporosis, as well as to age and generational effects. In addition, many elders cannot stand straight for accurate measurement. For these cases, total height can be estimated with regression equations based on knee height. The aims of this study were, firstly, to evaluate the applicability of regression equations based on knee height for estimation of stature and, secondly, to document the differences between measured and estimated height in a group of elderly Hispanics with postural problems (n = 166) in comparison with a group of elderly Hispanic without postural problems (n = 270). Using both, estimated and measured height, we also calculated the body mass index (BMI) of both groups of elders. Statistical analyses were done with paired t-tests, within sex and study group. Within the group with postural problems, estimated height was higher than the measured height for both men (p < or = 0.001) and women (p < or = 0.001). There were no significant differences between measured and estimated height in the group without postural problems. Furthermore, in the group with postural problems, BMI values calculated with estimated height were lower than those estimated with the measured height, and these differences were also significant for both men (p < or = 0.001) and women (p < or = 0.001). With the aging of the Latin American population, there is a need for more nutrition and health research among elders. In order to do this we need to develop and use methods and criteria appropriate for each population.

Aged↗

PubMed1999

Neurotrophin binding to the p75 receptor modulates Rho activity and axonal outgrowth.

While the neurotrophin receptor p75NTR is expressed by many developing neurons, its function in cells escaping elimination by programmed cell death remains unclear. The lack of intrinsic enzymatic activity of p75NTR prompted a search for protein interactors expressed in the developing retina, which resulted in the identification of the GTPase RhoA. In transfected cells, p75NTR activated RhoA, and neurotrophin binding abolished RhoA activation. In cultured neurons, inactivation of Rho proteins mimicked the effect of neurotrophins by increasing the rate of neurite elongation. In vivo, axonal outgrowth was retarded in mice carrying a mutation in the p75NTR gene. These results indicate that p75NTR modulates in a ligand-dependent fashion the activity of intracellular proteins known to regulate actin assembly.

Animals↗

PubMed1999

Why ruminators are poor problem solvers: clues from the phenomenology of dysphoric rumination.

The phenomenology of dysphoric rumination and its consequences for problem solving were explored in 3 studies. In Study 1, self-focused rumination, compared with distraction, led dysphoric participants to rate their own biggest problems as severe and unsolvable and to report a reduced likelihood of actually implementing their solutions. Clues into the mechanisms behind these findings were explored in Study 2. The results showed that dysphoric ruminative thought is characterized by a focus on personal problems combined with a negative tone, self-criticism, and self-blame for problems as well as reduced self-confidence, optimism, and perceived control. Finally, Study 3 revealed a direct relationship between the negatively biased content of ruminative thoughts and reduced willingness to solve one's problems. Implications of these findings for the consequences of self-focused rumination are discussed.

Adult↗

PubMed1999

Potassium, magnesium, and fruit and vegetable intakes are associated with greater bone mineral density in elderly men and women.

BACKGROUND: Osteoporosis and related fractures will be growing public health problems as the population ages. It is therefore of great importance to identify modifiable risk factors. OBJECTIVE: We investigated associations between dietary components contributing to an alkaline environment (dietary potassium, magnesium, and fruit and vegetables) and bone mineral density (BMD) in elderly subjects. DESIGN: Dietary intake measures were associated with both cross-sectional (baseline) and 4-y longitudinal change in BMD among surviving members of the original cohort of the Framingham Heart Study. Dietary and supplement intakes were assessed by food-frequency questionnaire, and BMD was measured at 3 hip sites and 1 forearm site. RESULTS: Greater potassium intake was significantly associated with greater BMD at all 4 sites for men and at 3 sites for women (P < 0.05). Magnesium intake was associated with greater BMD at one hip site for both men and women and in the forearm for men. Fruit and vegetable intake was associated with BMD at 3 sites for men and 2 for women. Greater intakes of potassium and magnesium were also each associated with less decline in BMD at 2 hip sites, and greater fruit and vegetable intake was associated with less decline at 1 hip site, in men. There were no significant associations between baseline diet and subsequent bone loss in women. CONCLUSION: These results support the hypothesis that alkaline-producing dietary components, specifically, potassium, magnesium, and fruit and vegetables, contribute to maintenance of BMD.

Aged↗