Larger Pool Size Research Articles

Effects of skin thickness, age, body fat, and sunlight on serum 25-hydroxyvitamin D

We tested the hypothesis that the age-related decline in skin thickness may contribute to the age-related decline in serum 25-hydroxyvitamin D [25(OH)D]. We measured skinfold thickness on the back of the hand, serum 25(OH)D, height, and weight in 433 normal postmenopausal women. We also noted the average daily hours of sunlight in the month in which the observations were made and in the preceding 2 mo. Serum 25(OH)D was positively related to hours of sunlight (with a time lag of 2 mo) and to skin thickness, and negatively to body mass index (wt/ht2). Serum 25(OH)D fell significantly after age 69 y. Seasonal variation of serum 25(OH)D was greater in lean than in fat subjects, which we attributed to the larger fat mass and consequent larger pool size in the latter group. The results suggest that the tendency for serum 25(OH)D to fall with age is due in part to the age-related decline in skin thickness.

Different antiviral potencies of BV-araU and related nucleoside analogues against herpes simplex virus type 1 in human cell lines and Vero cells.

Antiviral potencies against herpes simplex virus type 1 (HSV-1) of 1-beta-D-arabinofuranosyl-E-5-(2-bromovinyl)uracil (BV-araU) and ten other nucleoside analogues in human embryonic lung fibroblast (HEL) cells were compared with those in Vero cells. 5-Halogenovinylarabinosyluracils, highly active in HEL cells, were inactive against all three laboratory-stocked strains of HSV-1 but exerted moderate antiviral effects on three clinical isolates in Vero cells. The reduction in anti-HSV-1 potencies of other representative nucleoside analogues in Vero cells was much less than those of 5-halogenovinylarabinosyluracils. However, significant antiviral potencies of BV-araU against laboratory strains were observed in other human and monkey fibroblast cells including an immortalized cell line. Significant enhancement of antiviral activity of BV-araU against a laboratory strain and a clinical isolate was demonstrated in Vero cells by the addition of 0.1 microM aminopterin or FUdR, an inhibitor of thymidylate synthesis. The potentiated anti-HSV-1 activity in Vero cells was comparable to the potency in HEL cells without the inhibitor. These results suggested that high activity of thymidylate synthesis and a large thymidylate pool size in Vero cells seem to be related to loss of anti-HSV-1 potency of BV-araU. Original tissue type, species, and the immortality may not be responsible for the reduced antiviral activity of BV-araU in Vero cells.

Effects of grass maturity and legume substitution on large particle size reduction and small particle flow from the rumen of cattle.

Five ruminally and abomasally cannulated heifers (average weight 365 kg) were fed 6 kg/d of early (EOG) or late (LOG) maturity orchardgrass (OG) hay with or without replacement of EOG or LOG by 1.5 kg/d red clover hay (RC) in a 5 x 5 Latin square design. A fifth treatment, of LOG supplemented with 100 g/d casein (LOG + C), was used to evaluate the effect of supplemental protein. In situ fiber digestion, in vivo nutrient digestion and rate of passage from the rumen of large (retained on a 1.68-mm screen; labeled with La) and small (passed a 1.68-mm screen; labeled with Sm) EOG and LOG particles were determined in heifers fed these diets. Early maturity OG hay had 20% and 62%, respectively, greater (P less than .05) rates, and 61% and 73%, respectively, greater (P less than .05) extents of in situ NDF and ADF disappearance than LOG. Red clover substitution for OG increased (P less than .05) in situ extent of NDF disappearance by 6%. Early maturity OG large and small particles had 40% and 36%, respectively, greater (P less than .05) rates of passage than LOG. Large and small particle ruminal pool sizes were increased (P less than .05) by 115% and 33%, respectively, with LOG. Red clover substitution for OG increased (P less than .10) large and small particle output (kg/d) from the rumen by 15% and large particle rate of passage by 20%. Grass maturity may be affecting intake through rate of large particle size reduction and passage and small particle passage, although legume supplementation of OG may influence intake by increasing rate of large particle size reduction and passage.

The effect of harvesting intensity on the fate of applied 15N-ammonium to the organic horizons of a coniferous forest in N. Wales

15N-ammonium sulphate equivalent to 0.5 kg N/ha was added as a tracer to lysimeters containing the organic horizons of an acid forest soil. The effect of logging debris (brash), vegetation and second rotationPicea sitchensis seedlings on the amount of the15N found in various soil, vegetation and leachate pools was followed over a period of 60 days. Transformation of15N-ammonium to nitrate occurred within 24 hours. Although total nitrate leachate losses were high, tracer-derived nitrate represented only 0.4%–4.2% of the applied15N-ammonium. The atom % excess of the KCI-extractable organic-N pool was initially lower than for the inorganic species but due to the large pool size, consistently represented 3–6% of the applied15N-ammonium. The similarity of the atom % excess of the ammonium and nitrate pools indicated an autotrophic nitrification pathway.

Altered surfactant function and metabolism in rabbits with acute lung injury

Lung injury was induced in rabbits with N-nitroso-N-methylurethane (NNNMU), and saturated phosphatidylcholine (Sat PC) pool sizes and phospholipid compositions were measured in alveolar wash subfractions isolated by differential centrifugation (large and small surfactant aggregates). Surfactant metabolism also was studied using intravascular and intratracheal radiolabels. Protein permeability, gas exchange, and compliance were significantly abnormal as lung injury progressed. At peak injury, there was a decrease in the large aggregate Sat PC pool size in alveolar wash accompanied by increased uptake of Sat PC from the air space and increased specific activity of both intravascular and intratracheal radiolabels in lamellar bodies. This was followed by a marked rise in the small aggregate pool size in the alveolar wash and increased secretion of Sat PC into the air spaces. Phospholipid compositions, total phospholipid-to-protein ratios, and in vivo functional studies using a preterm ventilated rabbit model were abnormal for both large and small aggregate surfactant fractions from the lung-injured rabbits. These studies characterize quantitative, qualitative, and functional changes of alveolar wash surfactant subfractions in NNNMU-injured lungs.

Urinary excretion of [formula omitted] and recent N-6-3 fatty acid intake

Epidemiological studies were performed in a Japanese fishing village when catches of fish were highest and in a Japanese farming village with usual fish consumption. Intake of eicosapentaenoic, docosahexaenoic and also arachidonic acid were significantly higher in the fishing village during the 3 days of the study than in the farming village. The correlation between eicosapentaenoic acid intake on the day when urine was collected and excreion of Δ 17-2,3-dinor-6-keto-prostaglandin F 1α, the main urinary metabolite of prostaglandin I 3, was highly significant, whereas there was no correlation between arachidonic or linoleic acid intake and excretion of 2,3-dinor-6-keto-prostaglandin F 1α, the main urinary metabolite of prostaglandin I 2. We suggest that the arachidonic acid pool for prostaglandin I 2 production is not quickly influenced by dietary linoleic or arachidonic acid because of a large pool size of arachidonic acid and a slow conversion of linoleic acid to arachidonic acid, while prostaglandin I 3 formation is directly related to the intake of eicosapentaenoic acid.

Phosphorylation of fructose bisphosphate aldolase in Trypanosoma brucei

Methods were developed for in vivo labelling of trypanosome proteins with inorganic phosphate and the labelling of fructose bisphosphate aldolase and variant surface glycoprotein was investigated. It was found that the large pool size of phosphate in trypanosomes precludes detailed kinetic analyses. Aldolase contains low levels of phosphoserine but the function of this phosphorylation has yet to be determined.

The effect of zero HLA class I and II mismatching in cyclosporine-treated kidney transplant patients.

The effect of HLA matching on one-year first cadaver donor graft survival rates between best and worst matches was 6% (P less than 0.001) for A, B; 7% (P less than 0.001) for DR; 9% (P less than 0.001) for A, DR; 15% (P less than 0.001) for B, DR; and 17% (P less than 0.001) for A, B, DR. For second cadaver donor grafts, the differences were comparable. Analysis of the cyclosporine-treated patients separately yielded similar results: 5% (NS) for A, B; 7% (P less than 0.001) for DR; 13% (P less than 0.001) for A, DR; 16% (P less than 0.001) for B, DR; and 18% (P less than 0.001) for A, B, DR. The most significant effect of matching was achieved by zero mismatching B and DR antigens. The one-year graft survival for patients with zero A, B, DR mismatch was 88% with cyclosporine. Without cyclosporine, zero mismatched A, B, DR grafts survive at 84%; this difference is not statistically significant. Zero mismatching for class I and II antigens (that is, A, DR or B, DR with cyclosporine) gives one-year graft survivals of 84% and 87%, respectively. The zero mismatching HLA class I and II antigen effect is lost when even one antigen is mismatched. Transfusions improved the one-year graft survival 10% in cyclosporine-treated patients, but not in those who were not treated with cyclosporine. Seventy-one patients transfused with more than 4 units of blood, zero B, DR mismatched, and treated with cyclosporine had a 91% one-year graft survival. Recipient pool sizes for obtaining zero A, B, DR or B, DR mismatched donors are calculated. Zero A, B, DR mismatched patients can be transplanted at a 19% frequency with a 10,000 recipient pool. The success rate for zero mismatching of class I and class II antigens indicates that kidney sharing and large recipient pool sizes are a reasonable policy.

Lymphocyte function in human bone marrow. II. Characterization of an interleukin 2-sensitive T precursor-cell population.

In the present study of human bone marrow lymphocytes, we analyze a newly recognized population of T suppressor-cell precursors which are found in marrow only and which have the potential to inhibit immunoglobulin (Ig) production in vitro. Following exposure to interleukin 2 (IL2), suppressor precursors acquire E receptor, T3 determinants, suppressor function, and lectin responsiveness. To distinguish this population within the framework of T-cell ontogeny, it was compared to a previously described population of thymus-dependent helper T-cell precursors which express helper function following exposure to thymus-derived mediators. The two populations are completely distinct and can be separated on density gradients. Suppressor precursors expressed T8 and TAC (IL2-receptor) antigens prior to in vitro induction with IL2. The thymic hormone-dependent cells expressed T4 but not T8 or TAC determinants. In two patients with severe combined immunodeficiency disease (SCID), IL2-responsive precursor cells appeared only late after thymus epithelium transplantation, perhaps best explained by a model in which thymus-dependent differentiation pathways precede, induce, or seed pathways of extra-thymic T-cell differentiation. The large pool size of over 10(11) suppressor and helper precursor cells present in adult bone marrow suggests that these populations may play an important role in immune homeostasis.

Studies on synthesis and uptake of taurine in rat lens in vitro

The occurrence of large taurine pool sizes in the crystalline lens was further elucidated by studying the in vitro synthesis and uptake of taurine in the rat lens. It was observed that a time- and concentration-dependent synthesis of taurine from methionine occurred in the rat lens. The time curve for uptake was linear up to 4 hr and was not saturated up to 40 m m concentration of taurine. The uptake was inhibited by ouabain, cyanide, Ca 2+, GTP and cGMP but was not affected by ATP and cAMP. It is suggested that a dual mechanism exists for maintenance of high concentrations of taurine in the lens. Moreover, the uptake mechanism is energy-dependent.

Changes revealed by a tracer technique in the amino acid metabolism of thermodormant and non-dormant New York lettuce seeds.

The metabolism of glycerol-(14)C(U) in non-thermodormant New York lettuce seeds was compared with that in thermodormant ones in order to find metabolic changes and a possible osmotic substance(s) in the non-dormant seeds. The higher incorporation of radioactivity into cationic substances in the non-dormant seeds revealed rapid synthesis and large pool sizes for some amino acids, especially Gln and Glu, before radicle protrusion. The enormous accumulation of Gln and Glu in germinating seeds indicates that these amino acids may act as osmotic substances in the germination of New York lettuce seeds. There were no indications that an osmotic substance(s) is included in the neutral and acidic fractions of the 80%-ethanol extracts. Time course analyses of free amino acids showed changes in the metabolism of free amino acids, especially Arg and Asn, at the early stage (4 to 8 hr) of imbibition both in thermodormant and in non-dormant seeds. These data are evidence that the metabolism of amino acids in New York lettuce seeds was affected by temperature treatment from the early stage of imbibition.

Effects of carnitine administration fasting, and exercise on urinary carnitine excretion in man.

1. In this study, the carnitine level in 24-hr urine has been determined in males, (a) before and after a single dose of 500 mg (as carnitine) of DL-carnitine chloride, (b) during fasting, and (c) before and after a severe running program (3 x 2,000 m/8-8.5 min). 2. After the administration of DL-carnitine chloride, the urinary carnitine excretion was increased by only approximately 10% of the dose, suggesting a large body pool size of carnitine. 3. Urinary carnitine excretion was significantly increased during five-day fasting; a maximum level of 2.17 +/- 0.24 (mean and SD) mmoles/day was 4.6 times higher than the usual level of 0.47 +/- 0.10 mmoles/day (p less than 0.001). Respiratory quotients (RQ) decreased significantly (p less than 0.01) from the control value of 0.81 +/- 0.03 to the value of 0.75 +/- .02 after five-day fasting and was significantly correlated with urinary carnitine levels (r = 0.62, p less than 0.05). 4. The urinary excretion of carnitine increased slightly with heavy running exercise. 5. The results are discussed in relation to the physiologic regulation of the rate of carnitine synthesis.

SOME DYNAMIC ASPECTS OF BRAIN METABOLISM IN RATS GIVEN A PORTOCAVAL ANASTOMOSIS

Some dynamic aspects of brain metabolism in rats given a portocaval anastomosisThree weeks after portocaval shunt, when the only ultrastructural change in the CNS is watery swelling of astrocytes, the chronic hyperammonaemia so induced is associated with an increase of brain glutamine (330%), and a decrease of glutamate (90%) and glucose (63%). The metabolic fate of [2–14C] glucose was followed over a time course of 40 min after an intravenous injection. Details are given of a compartmental analysis of metabolic kinetic relationships, particularly of brain glutamate and glutamine. When applied to [2–14C]glucose data there was no evidence of an increased rate of glutamine synthesis in the operated rats. The increased labelling of glutamine could be accounted for by a larger pool size with a slower fractional turnover coefficient. In control rats [l‐14C]butyrate conferred label very rapidly on a small fraction of brain glutamine. Analysis showed there was little or no overlap between pools of amino acids labelled by [1–14C]butyrate and those labelled by [2–14C]glu‐cose. In operated animals there was a marked decrease in the total amount of labelled [l‐14C]butyrate entering the brain. Analysis showed some overlap between labelling of amino acids by [14C]butyrate and [14C]glucose, as well as several other changes. The biochemical differences found are likely to be causally related to the ultrastructural changes in astrocytes and lend support to previous concepts of morphological assignments to metabolic compartments.

Use of Indigenous Soil‐Rubidium Absorbed by Cotton Plants in Determining Labile Soil‐Potassium Pool Sizes

AbstractThe rubidium/potassium (Rb/K) ratios of natural soils and of most soil‐grown plants are higher than Rb/K ratios of many available fertilizer‐grade potassium salts as revealed by analyses of 24 samples of commercial K‐fertilizers. Low‐Rb K‐fertilizers of 0.02 mmoles Rb/mole K or lower may offer practicable means for field scale tracing of fertilizer‐K absorbed by crop plants when growing under normal management regimes. Whenever K‐fertilization results in lower Rb/K ratios appearing in fertilized plants, this dilution or “reversed‐tagging” of indigenous soil‐Rb with low Rb‐containing K‐fertilizers permits determinations of pool‐sizes of labile soil‐K. Four different soils were compared for NH4OAc extractable‐K, HNO3 extractable‐K, and the pool‐size of labile‐K as determined from Rb/K ratios of K‐fertilized cotton plants (Gossupium hirsutum L.). A large pool size of labile‐K does not necessarily mean that the K supplying power of a soil is large. The Rb/K ratios can also be used to calculate relative amounts of absorbed plant‐K originating from the indigenous soil‐pool vs. the plant‐K derived from a K‐fertilizer.