Biomedical subjects
C Castaneda
Publications and source records attributed to C Castaneda.
Resistance training to counteract the catabolism of a low-protein diet in patients with chronic renal insufficiency. A randomized, controlled trial.
BACKGROUND: Chronic renal insufficiency leads to muscle wasting, which may be exacerbated by low-protein diets prescribed to delay disease progression. Resistance training increases protein utilization and muscle mass. OBJECTIVE: To determine the efficacy of resistance training in improving protein utilization and muscle mass in patients with chronic renal insufficiency treated with a low-protein diet. DESIGN: Randomized, controlled trial. SETTING: Tufts University, Boston, Massachusetts. PATIENTS: 26 older patients with moderate renal insufficiency (17 men, 9 women) who had achieved stabilization on a low-protein diet. INTERVENTION: During a run-in period of 2 to 8 weeks, patients were instructed and their adherence to the low-protein diet (0.6 g/kg of body weight per day) was evaluated. They were randomly assigned to a low-protein diet plus resistance training (n = 14) or a low-protein diet alone (n = 12) for 12 weeks. MEASUREMENTS: Total body potassium, mid-thigh muscle area, type I and II muscle-fiber cross-sectional area, and protein turnover. RESULTS: Mean protein intake was 0.64 +/- 0.07 g/kg per day after stabilization. Total body potassium and type I and II muscle-fiber cross-sectional areas increased in patients who performed resistance training by a mean (+/-SD) of 4% +/- 8%, 24% +/- 31%, and 22% +/- 29%, respectively, compared with those who did not. Leucine oxidation and serum prealbumin levels also improved significantly. Patients assigned to resistance training maintained body weight compared with those who were not. Improvement in muscle strength was significantly greater with resistance training (32% +/- 14%) than without (-13% +/- 20%) (P < 0.001). CONCLUSION: By improving muscle mass, nutritional status, and function, resistance training seems to be effective against the catabolism of a low-protein diet and uremia in patients with renal failure.
Sarcopenia-understanding the dynamics of aging muscle.
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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.
Report of the IDECG Working Group on energy and macronutrient metabolism and requirements of the elderly.
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Relation among serum and tissue concentrations of lutein and zeaxanthin and macular pigment density.
BACKGROUND: Lutein and zeaxanthin are the only carotenoids in the macular region of the retina (referred to as macular pigment [MP]). Foods that are rich in lutein and zeaxanthin can increase MP density. Response to dietary lutein and zeaxanthin in other tissues has not been studied. OBJECTIVE: The objective of this study was to examine tissue responses to dietary lutein and zeaxanthin and relations among tissues in lutein and zeaxanthin concentrations. DESIGN: Seven subjects consumed spinach and corn, which contain lutein and zeaxanthin, with their daily diets for 15 wk. At 0, 4, 8, and 15 wk and 2 mo after the study, serum, buccal mucosa cells, and adipose tissue were analyzed for carotenoids, and MP density was measured. RESULTS: Serum and buccal cell concentrations of lutein increased significantly from baseline during dietary modification. Serum zeaxanthin concentrations were greater than at baseline only at 4 wk, whereas buccal cell and adipose tissue concentrations of zeaxanthin did not change. Adipose tissue lutein concentrations peaked at 8 wk. Changes in adipose tissue lutein concentration were inversely related to the changes in MP density, suggesting an interaction between adipose tissue and retina in lutein metabolism. To investigate the possibility of tissue interactions, we examined cross-sectional relations among serum, tissue, and dietary lutein concentrations, anthropometric measures, and MP density in healthy adults. Significant negative correlations were found between adipose tissue lutein concentrations and MP for women, but a significant positive relation was found for men. CONCLUSION: Sex differences in lutein metabolism may be an important factor in tissue interactions and in determining MP density.
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.
Association of muscle power with functional status in community-dwelling elderly women.
BACKGROUND: Identification of the physiologic factors most relevant to functional independence in the elderly population is critical for the design of effective interventions. It has been suggested that muscle power may be more directly related to impaired physical performance than muscle strength in elderly persons. We tested the hypothesis that peak muscle power is closely associated with self-reported functional status in sedentary elderly community-dwelling women. METHODS: We used baseline data that were collected as part of a 1-year randomized controlled clinical trial of a combined program of strength, power, and endurance training in 80 elderly women (mean age 74.8 +/- 5.0 years) with 3.2 +/- 1.9 chronic diseases, selected for baseline functional impairment and/or falls. RESULTS: Functional status at baseline was related in univariate analyses to physiologic capacity, habitual physical activity level, neuropsychological status, and medical diagnoses. Leg power had the strongest univariate correlation to self-reported functional status (r = -.47, p < .0001) of any of the physiologic factors we tested. In a forward stepwise regression model, leg press power and habitual physical activity level were the only two factors that contributed independently to functional status (r = .64, p < .0001), accounting for 40% of the variance in functional status. CONCLUSIONS: Leg power is a strong predictor of self-reported functional status in elderly women.
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.
Marginal protein intake results in reduced plasma IGF-I levels and skeletal muscle fiber atrophy in elderly women.
We investigated the effects of dietary protein on plasma IGF-I levels and muscle fiber cross-sectional area (CSA). Twelve healthy elderly women were randomly assigned to a weight-maintaining diet containing either 1.47 (marginal) or 2.94 (adequate) g protein/kg body cell mass (BCM)/d, (0.45 and 0.92 g/kg body weight/d, respectively) for 10wks. Plasma IGF-I levels and muscle fiber areas and distributions were evaluated at baseline and 10wks. After 10wks, both IGF-I and type I fiber CSA had declined significantly in subjects fed the marginal diet (30.1+/-2.1% and 32.7+/-7.9%, respectively) while they increased in those fed the adequate diet (19.5+/-7.0% and 22.3+/-7.5%, for IGF-I and type I CSA, respectively). The change in IGF-I was the only significantly associated with the change in type I fiber CSA (r2=0.70; p<0.03). These findings show that marginal dietary protein intakes will result in losses of muscle mass in the elderly and suggest a role for plasma IGF-I as a biochemical marker for the histological changes in skeletal muscle.
Potential benefits of resistance exercise training on nutritional status in renal failure.
Resistance or strength exercise training may help reverse the malnutrition common among patients in chronic renal failure and delay the progression of renal disease. Resistance training is characterized by resisting, lifting, and lowering weights. It results in muscle mass accretion, improved physical function, and slowed progression of muscle wasting. Resistance exercise training for a period of 8 to 12 weeks results in significant increases in muscle mass, muscle strength, and muscle function in frail "healthy" elderly individuals as well as in specific patient populations. States of malnutrition leading to muscle wasting directly affect lean tissue mass and functional capacity. Even at dietary protein intake below the Recommended Dietary Allowances, resistance training appears to exert an anabolic effect by improving energy intake and protein use allowing nitrogen retention. The potential benefits of resistance exercise extend beyond this direct impact on protein metabolism. They include improvements in functional capacity such as gait, balance, mobility, strength, exercise tolerance, improved glucose uptake, insulin sensitivity, and self-efficacy and self-esteem. Currently, the effects of resistance exercise in renal patients are unknown, although they are well shown in the case of other diseases. The potential benefits that resistance exercise training may have on muscle mass and function, nutritional status, hyperglycemia, disease progression, and the overall mental well-being of renal patients deserve further investigation. As an adjunct to current treatment modalities for chronic renal failure, resistance exercise may serve as a cost-effective, interdisciplinary, noninvasive approach to counteract malnutrition and improve the quality of life.
Conditions altering plasma concentrations of urea cycle and other amino acids in elderly human subjects.
OBJECTIVE: Describe plasma amino acid concentrations and total urinary amino acid excretion in subjects from an elderly female population. SUBJECTS: Fasting plasma samples, complete 24-hour urine samples, and 3-day diet records were obtained from 96 healthy postmenopausal women in one study and fasting plasma samples were obtained from an additional 44 subjects in 3 separate studies. In one study, nonfasting plasma samples were also collected. The subjects ranged in age from 49 to 80 years of age. Samples were obtained to allow the evaluation of the effects of fasting vs. nonfasting, normal vs. Alzheimers subjects, and level of protein intake effects. MEASURES OF OUTCOME: Heparinized plasma samples were deproteinized with a 5-sulfosalicylic acid solution and centrifuged at 14,900 x g. Deproteinized plasma and urine samples were analyzed for free amino acids on a Beckman System 6300 analyzer using a postcolumn reaction with ninhydrin to quantitate the amino acids. RESULTS AND CONCLUSIONS: It is concluded that: 1) From fasting plasma samples, 1 or 2 sampling days are sufficient to establish a characteristic concentration for most plasma amino acids. 2) Fasting amino acid concentrations do not reflect levels of dietary protein intake when dietary amino acid composition is similar. Shifts in fasting amino acid concentrations would be more indicative of changes in relative amounts of amino acids absorbed rather than level of dietary protein per se. 3) Totals of fasting plasma concentrations of arginine, citrulline and ornithine were relatively constant, but fluctuations occurred in the ratio of ornithine to arginine in the different populations; and 4) Patients with Alzheimers disease exhibited altered plasma ornithine and arginine concentrations relative to active or sedentary controls.
Elderly women accommodate to a low-protein diet with losses of body cell mass, muscle function, and immune response.
A 9-wk study of adaptation to marginal protein intakes was conducted in 12 elderly women. Subjects were randomly assigned to two groups fed a weight-maintenance diet containing either 1.47 (low) or 2.94 (adequate) g protein.kg body cell mass-1.d-1 (0.45 and 0.92 g.kg body wt-1.d-1, respectively). Mean nitrogen balance in the low-protein group remained negative throughout the study. These subjects experienced significant losses in lean tissue, immune response, and muscle function. The adequate-protein group was in nitrogen balance throughout the study, without changes in lean tissue, and with improvements in immune response, serum immunoglobulins, albumin, total protein values, and muscle function. Thus, elderly women fed the low-protein diet accommodated to the diet by compromising functional capacity, whereas those fed the adequate diet maintained functional capacity.
Protein turnover and energy metabolism of elderly women fed a low-protein diet.
The metabolic mechanisms of accommodation to a low-protein diet in elderly women were studied. Diets containing 1.47 (low) or 2.94 (adequate) g protein.kg body cell mass-1.d-1 (0.45 or 0.92 g.kg body weight-1.d-1, respectively) were fed for 10 wk. Fed state leucine kinetics, fasted and fed metabolic rate, and acute-phase responses to a bout of exercise were measured. Leucine uptake into protein, breakdown, and acute-phase responses were not significantly different within or between diet groups. In the low-protein group, leucine flux and oxidation were lower after 3 wk and oxidation continued to decrease throughout the 10-wk study. When expressed per body cell mass, metabolic rate increased over time in the low-protein group only. Leucine oxidation was a more sensitive index of the adequacy of protein intake than synthesis, flux, metabolic rate, or acute-phase response.
[Disappearance of tardive dyskinesia in a manic attack].
A 66 year-old man suffered of a manic-depressive illness. Tardive dyskinesia appeared after a treatment with chlorpromazine. Abnormal movements were present at normal and depressive states, but disappeared during manic phases. A few similar cases have been reported. The authors suggest that a modification in the sensibility of monoaminergic receptors could explain the disappearance of dyskinetic movements during mania.
[Significance of laparoscopy in the diagnosis of cholestasis in infants].
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