Acute phase response and energy balance in stable human immunodeficiency virus-infected patients: a doubly labeled water study.

We sought to assess possible associations of the acute phase response with energy balance as a cause of malnutrition in uncomplicated HIV-infection. Seven stable HIV-infected patients and 7 control subjects were followed for 2 weeks for blood chemistry, body composition, total and resting energy expenditure (TEE, REE), heart rate, energy intake, and physical activity; 6 patients were investigated for interleukin-2 receptor. TEE, REE, energy intake, and anthropometric data in patients and control subjects were very similar. However, physical activity, total body potassium, and bioimpedance phase angle were decreased (1.41 +/- 0.08 vs 1.55 +/- 0.9, 152 +/- 10 g vs 191 +/- 37 g, and 6.4 +/- 0.8 degrees vs 7.1 +/- 0.5 degrees; each P < .05), and mean heart rate, fibrinogen, and erythrocyte sedimentation rate were increased in HIV-infected patients (84 +/- 6 bpm vs 76 +/- 8 bpm, 4.3 +/- 1.2 g/L vs 2.5 +/- 0.4 g/L, and 21 +/- 13 mm vs 2 +/- 3 mm; P < .05). The deviation between the measured and the predicted REE in the patient group correlated positively with heart rate and serum interleukin-2 receptor concentrations (r = 0.83 and r = 0.91; P < .05). Possible increases in REE caused by an ongoing acute phase response may be counterbalanced by reduced physical activity that results in normal TEE in HIV infection.

Delta13C and deltaD values of Opuntia atacamensis depending on different environmental conditions in the Atacama desert of Northern Chile.

We analysed 13carbon and deuterium discrimination in Opuntia atacamensis PHIL. at three different sites in the Atacama desert in Northern Chile: At the western Andean slopes, influenced by summer rainfall, in the very arid Chilean central valley, and at coastal fog mountains. At the most arid site, the central valley, discrimination of 13C and D was less (delta-values less negative) and also discrimination more against deuterium. This is an aridity, not an altitude effect. The differences in 13C content may be due to some carbon fixation via the C3 photosynthetic pathway at the more humid sites. Deuterium enrichment at the arid sites might be due to greater discrimination of HDO against H2O during transpirational water loss.

Downward flux of water through roots (i.e. inverse hydraulic lift) in dry Kalahari sands.

Downward transport of water in roots, in the following termed "inverse hydraulic lift," has previously been shown with heat flux techniques. But water flow into deeper soil layers was demonstrated in this study for the first time when investigating several perennial grass species of the Kalahari Desert under field conditions. Deuterium labelling was used to show that water acquired by roots from moist sand in the upper profile was transported through the root system to roots deeper in the profile and released into the dry sand at these depths. Inverse hydraulic lift may serve as an important mechanism to facilitate root growth through the dry soil layers underlaying the upper profile where precipitation penetrates. This may allow roots to reach deep sources of moisture in water-limited ecosystems such as the Kalahari Desert.

Diversity, metabolic types and δ13C carbon isotope ratios in the grass flora of Namibia in relation to growth form, precipitation and habitat conditions.

The grass flora of Namibia (374 species in 110 genera) shows surprisingly little variation in δ13C values along a rainfall gradient (50-600 mm) and in different habitat conditions. However, there are significant differences in the δ13C values between the metabolic types of the C4 photosynthetic pathway. NADP-ME-type C4 species exhibit the highest δ13C values (-11.7 ‰) and occur mainly in regions with high rainfall. NAD-ME-type C4 species have significantly lower δ13C values (-13.4 ‰) and dominate in the most arid part of the precipitation regime. PCK-type C4 species play an intermediate role (-12.5 ‰) and reach a maximum abundance in areas of intermediate precipitation. This pattern is also evident in genera containing species of different metabolic types. Within the same genus NAD species reach more negative δ13C values than PCK species and δ13C values decreased with rainfall. Also in Aristida, with NADP-ME-type photosynthesis, δ13C values decreased from -11 ‰ in the inland region (600 mm precipitation) to -15 ‰ near the coast (150 mm precipitation), which is a change in discrimination which is otherwise associated by a change in metabolism. The exceptional C3 species Eragrostis walteri and Panicum heterostachyum are coastal species experiencing 50 mm precipitation only. Many of the rare species and monotypic genera grow in moist habitats rather than in the desert, and they are not different in their carbon isotope ratios from the more common flora. The role of species diversity with respect to habitat occupation and carbon metabolism is discussed.

Physical activity, total energy expenditure, and food intake in grossly obese and normal weight women.

The doubly labeled water method was used to measure average daily total energy expenditure (TEE) in 10 healthy normal weight women classified as unrestrained eaters and in 10 grossly obese women. The body mass index was 20.0 +/- 1.3 kg/m2 in the control group and 37.4 +/- 8.1 kg/m2 for the obese group. TEE was measured over a 2-week period. TEE was 2,357 +/- 504 kcal/day for the controls and 3,708 +/- 367 kcal/day for the obese group during a cognitive-behavioral treatment.

Resting metabolic rate and total energy expenditure in acute and weight recovered patients with anorexia nervosa and in healthy young women.

Because little is known about energy requirements in anorectic patients before and after weight gain we measured resting metabolic rate (RMR) by indirect calorimetry and total energy expenditure (TEE) by the doubly labeled water method in 6 patients with anorexia nervosa (body mass index [BMI] = 15.1 +/- 1.3 kg/m2), in 6 weight-recovered anorectics (BMI = 21.2 +/- 2.1 kg/m2), and in 12 healthy age-matched women (BMI = 20.5 +/- 1.9 kg/m2). No significant differences were found between the weight-recovered anorectic women and the healthy controls in RMR (1,330 +/- 131 kcal/day [weight-recovered]; 1,419 +/- 197 [controls]) and in TEE (2,602 +/- 637 kcal/day [weight-recovered]; 2,596 +/- 493 kcal/day [controls]). The RMR was significantly lower in the acutely ill anorectic patients (1,171 +/- 113 kcal/24 hr) than in weight-recovered anorectics and in healthy controls. The TEE was significantly lower in the anorectic group (1,946 +/- 192 kcal/day) than in the healthy controls.

Average total energy expenditure in anorexia nervosa, bulimia nervosa, and healthy young women.

The double-labeled water method was used to measure average daily total energy expenditure (EE) in 11 healthy normal-weight women classified as unrestrained eaters, in 8 patients with anorexia nervosa, and in 8 patients with bulimia nervosa. The body mass index was 20.0 +/- 1.3 kg/m2 in the control group, 15.2 +/- 5.6 kg/m2 in the anorectic groups, and 19.7 +/- 1.9 kg/m2 in the bulimic group. EE was measured over a 2-week period during which weight remained constant in all groups and was 2357 +/- 504 kcal/day for the controls, 2510 +/- 920 kcal/day for the bulimics, and 2899 +/- 656 kcal/day for the anorectics. Differences were not significant among groups. Physical activity was recorded in diaries by all subjects. Anorectic patients showed significantly more activity than all other groups. The data suggest that EE is high in anorectic patients as a consequence of physical activity.

[Determination of the origin of drugs by measuring natural isotope contents: D/H and 13C/12C ratios of some diazepam samples (author's transl)]. / Herkunftsbestimmung von Arzneimitteln durch Messung von natürlichen Isotopenverhältnissen: D/H und 13C/12C Verhältnisse einiger Proben von Diazepam

The precise determination of the natural isotopic abundance ratios of carbon and hydrogen in several production batches of the commercial product 7-chlor-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-on (diazepam) gave results which allowed certain batches to be differentiated. The differences in the ratios appear to be mainly due to differences in the isotopic composition of the (fossile) starting materials of the synthesis. The measurement of the natural isotopic ratios may therefore offer another possibility to determine the origin of a drug.

Hydrogen isotope discrimination in higher plants: Correlations with photosynthetic pathway and environment.

The ratio of deuterium to hydrogen (expressed as δD) in hydrogen released as water during the combustion of dried plant material was examined. The δD value (metabolic hydrogen) determined on plant materials grown under controlled conditions is correlated with pathways of photosynthetic carbon metabolism. C3 plants show mean δD values of-132‰ for shoots and -117‰ for roots; C4 plants show mean δD values of -91‰ for shoots and-77‰ for roots and CAM plants a δD value of-75‰ for roots and shoots. The difference between the δD value of shoot material from C3 and C4 plants was confirmed in species growing under a range of glasshouse conditions. This difference in δD value between C3 and C4 species does not appear to be due to differences in the δD value (tissue water) in the plants as a result of physical fractionation of hydrogen isotopes during transpiration. In C3 and C4 plants the hydrogen isotope discrimination is in the same direction as the carbon isotope discrimination and factors contributing to the difference in δD values are discussed. In CAM plants grown in the laboratory or collected from the field δD values range from-75‰ to +50‰ and are correlated with δ(13)C values. When deprived of water, the δD value (metabolic hydrogen) in both soluble and insoluble material in leaves of Kalanchoe daigremontiana Hamet et Perr., becomes less negative. These changes may reflect the deuterium enrichment of tissue water during transpiration, or in field conditions, may reflect the different δD value of available water in areas of increasing aridity. Whatever the origin of the variable δD value in CAM plants, this parameter may be a useful index of the water relations of these plants under natural conditions.

Eco-physiological studies on Indian arid zone plants : V. A. Screening of some species for the C4-pathway of photosynthetic CO2-fixation.

Plants of the Indian desert belonging to 29 families, 85 genera and 105 species of angiosperms were screened for the possible occurrence of the C4-pathway of photosynthetic CO2-fixation. The criteria used for screening were leaf anatomy and/or δ13C values. The results indicated the occurrence of the C4-pathway in members of 3 new families (Acanthaceae, Cleomaceae, Scrophulariaceae), 10 new genera (Aerva, Anticharis, Blepharis, Elyonurus, Glossocardia 1 , Gynandropsis, Melanocenchris, Sehima, Sesuvium, Zalaeya) and 34 new species of the angiosperms. All the grasses investigated were found to possess the C4-pathway. Cuscuta hyalina, a phloem-parasite, growing on C4 hosts (Tribulus, Zalaeya) also revealed δ13C value very close to that found in the host plants.

Carbon isotope discrimination in alpine succulent plants supposed to be capable of crassulacean acid metabolism (CAM).

1. The 4 alpine species of Sempervivum (S. arachnoideum L., S. montanum L., S. soboliferum Sims, S. wulfenii Hoppe) analyzed in this study showed acidification during the dark period in their natural habitat. The δ13C value of these species varied according to the water supply at their natural habitat, being less negative at dry sites. These data are consistent with a larger contribution of dark CO2 fixation via Phosphoenolpyruvate-Carboxylase in relation to light CO2 fixation via Ribulose-1, 5-diphosphate Carboxylase. These alpine Sempervivum spp. behave, therefore, like typical CAM-plants. 2. In contrast, the 3 alpine species of Sedum analyzed in this respect (S. acre. L., S. alpestre Vill., S. rosea (L.) Scop.) showed no pronounced dark acidification. The δ13C value of the 8 alpine Sedum species examined in this study (the 3 mentioned above and S. album L., S. atratum L., S. dasyphyllum L., S. reflexum L., S. sexangulare L.) was much more negative than in the Sempervivum spp., indicating that the dark CO2 fixation does not play a great role in the carbon metabolism of the alpine Sedum spp. in the natural habitats. Water supply in the natural habitat has no clear-cut influence on the δ13C value. 3. All alpine species of Saxifraga analysed (S. seloides L., S. oppositifolia L., S. bryoides L., S. aizoides L., S. squarrosa Sieber, S. paniculata Mill., S. caesia L.) show δ13C values typical of C3 plants and they were not influended by the water conditions in the natural sites. Saxifraga paniculata showed no dark acidification in its natural habitat and we suspect that alpine Saxifrages are not CAM plants. 4. Based on δ13C values the alpine plants Pinguicula alpina L., Thesium alpinum L., and Linaria alpina (L.) Mill. are typical C3 plants.