Assessment of total body stores of vitamin A in Guatemalan elderly by the deuterated-retinol-dilution method

BACKGROUND: Deuterated retinol dilution (DRD) gives quantitative estimates of total body stores of vitamin A. OBJECTIVES: In elderly people, we studied 1) the time when an oral dose of deuterated vitamin A equilibrates with body stores, 2) whether serum ratios of deuterated to nondeuterated retinol (D:H) at 3 or 6 d postdosing predicted body stores, and 3) the ability of DRD to detect changes in the size of the body vitamin A pool. DESIGN: A 10-mg oral dose of [2H4]retinyl acetate was administered to 60-81-y-old Guatemalans (n = 47); percentage enrichment of serum retinol with deuterated retinol was determined at 1-3 time points per subject at 3, 6, 7, 14, 20, 21, and 54 d. In subjects from whom blood was obtained at 3 and 21 d (n = 15) and at 6 and 20 d (n = 9), total body stores were calculated by using the formula of Furr et al (Am J Clin Nutr 1989;49:713-6) with 21- or 20-d data and correlated with serum D:H at 3 or 6 d postdosing. Nine subjects received diets containing 982+/-20 microg RE (x+/-SEM) plus 800 microg RE as retinyl acetate supplements for 32 d. DRD, serum retinol, and relative dose response were used to assess vitamin A status before and after the intervention. RESULTS: Deuterated retinol equilibrated with the body pool by 20 d postdosing. Vitamin A supplementation for 32 d increased body stores, although unexplained exaggerated increases were seen in some subjects. An inverse linear relation was found between estimates of body stores and serum D:H at 3 d postdosing (r = -0.75, P = 0.002); at 6 d postdosing, the correlation was weaker. CONCLUSIONS: DRD can detect changes in total body stores of vitamin A, although factors affecting serum D:H need to be elucidated. Serum D:H 3 d postdosing might be used as an early indicator of total body stores of vitamin A, although a predictive equation will need to be developed.     

GIRK4 confers appropriate processing and cell surface localization to G-protein-gated potassium channels

GIRK1 and GIRK4 subunits combine to form the heterotetrameric acetylcholine-activated potassium current (IKACh) channel in pacemaker cells of the heart. The channel is activated by direct binding of G-protein Gbetagamma subunits. The GIRK1 subunit is atypical in the GIRK family in having a unique ( approximately 125-amino acid) domain in its distal C terminus. GIRK1 cannot form functional channels by itself but must combine with another GIRK family member (GIRK2, GIRK3, or GIRK4), which are themselves capable of forming functional homotetramers. Here we show, using an extracellularly Flag-tagged GIRK1 subunit, that GIRK1 requires association with GIRK4 for cell surface localization. Furthermore, GIRK1 homomultimers reside in core-glycosylated and nonglycosylated states. Coexpression of GIRK4 caused the appearance of the mature glycosylated form of GIRK1. [35S]Methionine pulse-labeling experiments demonstrated that GIRK4 associates with GIRK1 either during or shortly after subunit synthesis. Mutant and chimeric channel subunits were utilized to identify domains responsible for GIRK1 localization. Truncation of the unique C-terminal domain of Delta374-501 resulted in an intracellular GIRK1 subunit that produced normal IKACh-like channels when coexpressed with GIRK4. Chimeras containing the C-terminal domain of GIRK1 from amino acid 194 to 501 were intracellularly localized, whereas chimeras containing the C terminus of GIRK4 localized to the cell surface. Deletion analysis of the GIRK4 C terminus identified a 25-amino acid region required for cell surface targeting of GIRK1/GIRK4 heterotetramers and a 25-amino acid region required for cell surface localization of GIRK4 homotetramers. GIRK1 appeared intracellular in atrial myocytes isolated from GIRK4 knockout mice and was not maturely glycosylated, supporting an essential role for GIRK4 in the processing and cell surface localization of IKACh in vivo.     

Evaluation of a multicomponent, behaviorally oriented, problem-based "summer school" program for adolescents with diabetes

A 2-week summer school program, combining problem-based learning with behavior therapy, was developed to help adolescents with insulin-dependent diabetes improve their ability to cope with obstacles to dietary management. Ten students participated in a first session, and 9 participated in a second session, serving as a waiting list control group. Outcomes were evaluated pre- and postsession and at a 4-month follow-up using 3-day food diaries, blood glucose data, and paper-and-pencil tests of diabetes-related knowledge, self-efficacy, coping strategies, and general problem solving. Improvements were observed in self-efficacy, problem-solving skills, and self-reported coping strategies. No significant changes were observed in daily intake of fat, cholesterol, calories, mean blood glucose levels or blood glucose variability, and diabetes knowledge. Comparisons between the first group and the waiting list control group do not allow the significant pre-post changes to be clearly attributed to the summer school program.     

Effects of cereal breakfasts on postprandial glucose,appetite regulation and voluntary energy intake at a subsequent standardized lunch; focusing on rye products

Background  

Rye products have been demonstrated to lower the acute insulin demand, induce a low and prolonged blood glucose response (high Glycemic Profile, GP) and reduce subclinical inflammation. These products may therefore contribute to a lowered risk of obesity, type 2 diabetes and cardio vascular disease. The objective of the present paper was to evaluate the mechanism for a reduced postprandial insulin demand with rye products, and to explore possible appetite regulating properties.     

Geographic variation in the calls of wild chimpanzees: a reassessment

Male chimpanzees produce a species-typical call, the pant hoot, to communicate to conspecifics over long-distances. Calls given by males from the well-known Gombe and Mahale populations typically consist of four different phases: an introduction, build-up, climax, and let-down. Recent observations suggest that chimpanzees living in the Kibale National Park, Uganda, consistently give calls that lack a build-up and are thus qualitatively distinguishable acoustically from those made by other East African conspecifics. We analyzed additional recordings from Mahale and Kibale to re-examine geographic variation in chimpanzee calls. Results indicate that males from both sites produce pant hoots containing all four parts of the call. Calls made by chimpanzees from the two populations, however, differ in quantitative acoustic measures. Specifically, males at Kibale initiate their calls with significantly longer elements and build-up over briefer periods at slower rates than individuals from Mahale. Kibale males also deliver acoustically less variable calls than chimpanzees at Mahale. Although climax elements do not differ between populations in any single acoustic feature, discriminant function analysis reveals that acoustic variables can be used in combination to assign calls to the correct population at rates higher than that expected by chance. Ecological factors related to differences in habitat acoustics, the sound environment of the local biota, and body size are likely to account for these observed macrogeographic variations in chimpanzee calls.