ISSN:0731-5724    

DOI:10.1080/07315724.1990.10720342

出版商:Routledge    

年代:1990

数据来源: Taylor

摘要:

Ornithine alpha-ketoglutarate (OKG) has been useful as an adjuvant of enteral and parenteral nutrition. However, its metabolism and mechanism of action remain unclear although it is known that alpha-ketoglutarate (alpha KG) and ornithine (ORN) follow, in part, common metabolic pathways. Six fasting healthy male subjects underwent three separate oral load tests: (i) they received 10 g of OKG (i.e., 3.6 g of alpha KG and 6.4 g of ORN); (ii) 6.4 g of ORN as ornithine hydrochloride, and (iii) 3.6 g of alpha KG as calcium alpha-ketoglutarate. Blood was drawn 15 times over a five-hour period for measurements of plasma amino acids, alpha KG, insulin, and glucagon. After OKG and ORN administration, plasma ORN peaked at 60-75 min (494 +/−91 and 541 +/−85 mumol/L). The increase in plasma alpha KG was very small. OKG, alpha KG, and ORN all increased glutamate concentrations at 60 min (mean: +43%, +68%, +68%, respectively, p less than 0.05 compared to basal values). However, only OKG increased proline and arginine levels at 60 min (mean: +35%, p less than 0.01 and mean: +41%, p less than 0.05). Furthermore, glutamate, proline, and arginine concentrations correlated linearly with ornithine levels at 60 min. Finally, OKG increased insulinemia and glucagonemia (mean: +24% at 15 min, p less than 0.05 and +30% at 60 min, p less than 0.01, respectively). These data provide evidence that the combination of ORN and alpha KG modifies amino acid metabolism in a way which is not observed when they are administered separately. In addition, the OKG-mediated increase in insulin levels probably does not appear to result from a direct action of ORN on pancreatic secretion.

ISSN:0731-5724    

DOI:10.1080/07315724.1990.10720343

出版商:Routledge    

年代:1990

数据来源: Taylor

摘要:

Three family members are reported with functional symptoms considered to be caused by intracellular deficiency of thiamin. Persistence of desaturation of erythrocyte transketolase in the face of megadose thiamin hydrochloride (THCl), accompanied by a balanced multivitamin and mineral formula, suggested a familial thiamin dependency state. Each of three individuals responded clinically to the administration of thiamin tetrahydrofurfuryl disulfide (TTFD), and erythrocyte transketolase (TKA) became fully saturated with thiamin pyrophosphate (TPP). Dysautonomic symptoms observed are compared with those seen in classical beriberi, the nutritional prototype for dysautonomia, and changes in blood pressure are described which support this premise. Although there is no proof from the laboratory, it is hypothesized that the biochemical lesion might be due either to malabsorption of thiamin or its inadequate phosphorylation.

ISSN:0731-5724    

DOI:10.1080/07315724.1990.10720344

出版商:Routledge    

年代:1990

数据来源: Taylor

摘要:

In a nationwide survey the nutritional status was assessed of 539 apparently healthy, independently living elderly aged 65-79 years. Anthropometric data showed no energy deficits. The prevalence of anemia was 4 and 1% among men and women, respectively. Many elderly showed a low level of 25-hydroxyvitamin D in plasma (less than 31 nmol/L: men 35%; women 43%), indicating a marginal status. Although the prevalence of low blood levels of folate, pyridoxal-5′-phosphate, and total carotenoids was higher among the elderly than among younger adults, clear (clinical) signs of nutritional deficiencies were not observed. Prevalence of obesity (13%), hypercholesterolemia (38%), and hypertension (63%) was found to be high, the percentages being higher for women than for men. Several indicators of the nutritional status appeared to differ among age groups. It is concluded that few differences can be considered as being due to physiological aging, which finding should be reflected in reference values for elderly people.

ISSN:0731-5724    

DOI:10.1080/07315724.1990.10720345

出版商:Routledge    

年代:1990

数据来源: Taylor

ISSN:0731-5724    

DOI:10.1080/07315724.1990.10720346

出版商:Routledge    

年代:1990

数据来源: Taylor

摘要:

A diet fortified with calcium carbonate has been reported to reduce blood pressure in low-renin and salt-sensitive hypertensive patients. We have therefore examined the effect of increased dietary calcium on the development of reduced renal mass-saline hypertension in rats, a classical, low-renin, volume, and sodium-dependent model of hypertension. Rats with 70-75% reduction in renal mass were divided into experimental and control groups. The experimental rats were fed a sodium-free diet supplemented with calcium carbonate (2.0% calcium) and drank 1% saline for 5 weeks. Control rats consumed the salt-free diet and drank 1% saline for the same period. In control rats, as previously observed, blood pressure progressive increased from a control value of 120.0 +/−1.2 to 174.2 +/−1.2 mm Hg by the fifth week. In contrast, in the calcium-supplemented rats the development of hypertension was significantly attenuated; the blood pressure only increased from 117.0 +/−1.2 to 134.0 +/−3.8 mm Hg by the fifth week. This was associated with a 30% decrease in saline intake by the fifth week, with proportionate decreases in urine volume and sodium excretion but not potassium excretion. Urinary magnesium excretion increased. No such changes were seen in control rats. At the end of the treatment period, plasma levels of sodium, potassium, calcium, creatinine, BUN, and protein were not different, but plasma chloride and magnesium were lower in experimental rats; vascular smooth muscle cell membrane potentials were also not different. These data show that dietary calcium carbonate can attenuate the development of reduced renal mass-saline hypertension in the rat, possibly in part by altering sodium and water intake.

ISSN:0731-5724    

DOI:10.1080/07315724.1990.10720347

出版商:Routledge    

年代:1990

数据来源: Taylor

摘要:

The present study investigated the perception of sweetness of aspartame in comparison to various concentrations of sucrose. Twenty-seven subjects were randomly assigned to taste a chilled or room temperature Kool-Aid beverage sweetened with either aspartame or five different concentrations of sucrose. Subjects assessed the perceived similarity in sweetness of an aspartame-aspartame pair and five different aspartame-sucrose pairings and rated each beverage on five bipolar adjectives. Analysis of the similarity ratings revealed that subjects did not perceive the pairs of beverages to differ in perceived sweetness. Analysis of the adjective ratings revealed that aspartame and the lower sucrose concentrations were perceived as being less sweet and more sour than the higher sucrose concentrations.

ISSN:0731-5724    

DOI:10.1080/07315724.1990.10720348

出版商:Routledge    

年代:1990

数据来源: Taylor

摘要:

This study compared magnesium oxide and magnesium citrate with respect to in vitro solubility and in vivo gastrointestinal absorbability. The solubility of 25 mmol magnesium citrate and magnesium oxide was examined in vitro in solutions containing varying amounts of hydrochloric acid (0-24.2 mEq) in 300 ml distilled water intended to mimic achlorhydric to peak acid secretory states. Magnesium oxide was virtually insoluble in water and only 43% soluble in simulated peak acid secretion (24.2 mEq hydrochloric acid/300 ml). Magnesium citrate had high solubility even in water (55%) and was substantially more soluble than magnesium oxide in all states of acid secretion. Reprecipitation of magnesium citrate and magnesium oxide did not occur when the filtrates from the solubility studies were titrated to pH 6 and 7 to stimulate pancreatic bicarbonate secretion. Approximately 65% of magnesium citrate was complexed as soluble magnesium citrate, whereas magnesium complexation was not present in the magnesium oxide system. Magnesium absorption from the two magnesium salts was measured in vivo in normal volunteers by assessing the rise in urinary magnesium following oral magnesium load. The increment in urinary magnesium following magnesium citrate load (25 mmol) was significantly higher than that obtained from magnesium oxide load (during 4 hours post-load, 0.22 vs 0.006 mg/mg creatinine, p less than 0.05; during second 2 hours post-load, 0.035 vs 0.008 mg/mg creatinine, p less than 0.05). Thus, magnesium citrate was more soluble and bioavailable than magnesium oxide.

ISSN:0731-5724    

DOI:10.1080/07315724.1990.10720349

出版商:Routledge    

年代:1990

数据来源: Taylor

ISSN:0731-5724    

DOI:10.1080/07315724.1990.10720350

出版商:Routledge    

年代:1990

数据来源: Taylor

摘要:

Blood platelet function and possible involvement in death of hypomagnesemic ruminants was investigated with 26 Angus cows, 15 mature Hampshire wethers, eight Finnish-Hampshire ewes, and 36 growing Dorset lambs. Hypomagnesemia was induced by feeding vegetative spring tall fescue to 13 cows and semipurified diets low in Mg to nine wethers, four ewes, and 18 lambs. In comparison with controls, dietary treatments reduced plasma Mg concentrations 55% in cows, 36% in wethers, 66% in ewes, and 78% in lambs. Hypomagnesemia reduced in vitro reactivity of cow and lamb platelets to thrombin, ADP, and platelet active collagen, but in vitro tests may not accurately reflect in vivo platelet reactivity. Microscopic examination of platelet-rich plasma revealed a threefold increase in clumped platelets from four hypomagnesemic ewes compared to four normomagnesemic ewes. This suggests that in vivo activation and exhaustion of platelets may have contributed to reduced in vitro platelet reactivity. Six of 18 hypomagnesemic lambs died spontaneously in tetany after 2-12 months on low-Mg diets. Heart and lung lesions were markedly similar to pathological changes induced in other lambs by intravascular activation of platelets with 500 micrograms of vascular collagen fibrils per kg body weight injected intravenously. These results suggest the possibility of abnormal blood platelet activation as a significant mortality risk factor in severe hypomagnesemia.

ISSN:0731-5724    

DOI:10.1080/07315724.1990.10720351

出版商:Routledge    

年代:1990

数据来源: Taylor