Adrenocorticotropic hormone increases hydrolysis of B-6 vitamers in swine adrenal glands.

Shipping stress is an economic problem because of its effect on meat quality. Because shipping increases plasma cortisol and pyridoxal 5'-phosphate interacts with steroid hormones, we examined the interaction between adrenocorticotropic hormone (ACTH) and vitamin B-6 metabolism in pigs. Six crossbred pigs with ear vein catheters received 50 IU of porcine ACTH intravenously at 3-h intervals from 0800 to 2100 h on d 1-3 and 100 IU intramuscularly at 0800, 1400 and 2000 h on d 6 and 7. Controls received saline. ACTH had no effect on pyridoxal 5'-phosphate in adrenal tissue but decreased pyridoxamine 5'-phosphate from 6.1 +/- 0.7 to 4.7 +/- 1.0 nmol/g (P < 0.05). Adrenal pyridoxal and pyridoxamine concentrations were 0.4 +/- 0.1 nmol/g in controls and 1.1 +/- 0.3 and 1.3 +/- 0.5 nmol/g, respectively, in ACTH-treated pigs (P < 0.01). Pyridoxal 5'-phosphate phosphatase activity [median (25-75 percentile value)] at pH 7.4 in adrenal tissue was 66.6 (47.8-75.5) nmol/(g. min) in the controls and 764 (626-771) in the ACTH-treated pigs (P < 0.01). There was no significant difference in pyridoxal kinase activity. However, kinase activity in the adrenals was about twice as high as in other tissues. These data suggest an active turnover of vitamin B-6 in adrenal tissue.     

新生儿脐带血促肾上腺皮质激素、皮质醇水平的影响因素研究

目的 分析健康足月儿促肾上腺皮质激素(ACTH)、皮质醇(COR)的水平及其影响因素,为新生儿的预防保健提供理论支持。方法 选取2018年10月-2019年2月空军医学特色中心妇产科出生的88例新生儿为研究对象,检测脐带血ACTH、COR水平,用最优尺度回归分析的方法探讨分娩方式、胎龄、性别、出生体重、母亲孕期情况对新生儿脐带血ACTH、COR水平的影响。结果 88例新生儿脐带血ACTH水平为(172.11±93.93)pg/ml,COR水平为(310.05±125.33)ng/ml。单因素分析结果显示,不同分娩方式、胎龄的新生儿脐带血COR水平的差异具有统计学意义(P＜0.01),而不同性别、出生体重、母亲孕期健康情况的新生儿COR水平差异无统计学意义,不同分娩方式、胎龄、性别、出生体重、母亲孕期情况的新生儿的ACTH水平差异无统计学意义(P>0.05)。最优尺度回归分析显示,分娩方式、性别、胎龄和体重对脐带血COR的水平有显著影响(β=-0.522,-0.221,0.284,-0.260,P＜0.05)。结论 分娩方式、胎龄是健康足月儿脐带血COR水平的主要影响因素,而本研究所涉及的胎龄、性别、出生体重、母亲孕期情况等均不影响ACTH水平。     

Strategies for healthy weight loss: from vitamin C to the glycemic response

America is experiencing a major obesity epidemic. The ramifications of this epidemic are immense since obesity is associated with chronic metabolic abnormalities such as insulin resistance, dyslipidemia, and heart disease. Reduced physical activity and/or increased energy intakes are important factors in this epidemic. Additionally, a genetic susceptibility to obesity is associated with gene polymorphisms affecting biochemical pathways that regulate fat oxidation, energy expenditure, or energy intake. However, these pathways are also impacted by specific foods and nutrients. Vitamin C status is inversely related to body mass. Individuals with adequate vitamin C status oxidize 30% more fat during a moderate exercise bout than individuals with low vitamin C status; thus, vitamin C depleted individuals may be more resistant to fat mass loss. Food choices can impact post-meal satiety and hunger. High-protein foods promote postprandial thermogenesis and greater satiety as compared to high-carbohydrate, low-fat foods; thus, diet regimens high in protein foods may improve diet compliance and diet effectiveness. Vinegar and peanut ingestion can reduce the glycemic effect of a meal, a phenomenon that has been related to satiety and reduced food consumption. Thus, the effectiveness of regular exercise and a prudent diet for weight loss may be enhanced by attention to specific diet details.     

Lipid peroxidation in relation to vitamin C and vitamin E levels

Oxidative stress plays an important contributory role in the pathogenesis of age-related chronic diseases. Increased lipid peroxidation process is caused by an enhanced free radical formation together with a higher supply of substrates and by an insufficient defense by antioxidants as well. Levels of malondialdehyde to content of lipid peroxidation substrates (polyunsaturated fatty acids), promoters (homocysteine--hydroxyl radical producer) and inhibitors (essential vitamins C and E) were estimated in a group (n=92) of subjective healthy adults randomly selected from general population. The relationship of malondialdehyde levels to values of peroxidisability index of fatty acids as well as to levels of homocysteine is significantly positive linear A significant inverse linear correlation between malondialdehyde levels and natural antioxidant levels (vitamin C, vitamin E) was recorded. Lipid peroxidation products (conjugated dienes of fatty acids--initial, malondialdehyde--secondary) are significantly increased in groups of subjects with deficient levels of vitamin C (below the limit from antioxidative point of view), vitamin E and both vitamins, if compared to group with normal vitamin levels (over limit in accordance with antioxidative criterion). The results document that the deficiency in two key antioxidants for lipid peroxidation inhibition means the insufficient defense against free radicals and the increased lipid peroxidation.     

Influence of vitamin C restriction on guinea pig adrenal calcium and plasma corticosteroids.

Some aspects of adrenocortical function were investigated in young male guinea pigs fed an ascorbic acid (AsA)-deficient diet for 7 days, followed by 0.1 mg AsA/100 g body weight/day for 4 days; pair-fed guinea pigs served as controls. Ninety minutes prior to killine, all guinea pigs received either an adrenocorticotropic hormone (ACTH) or saline injection, and 30 minutes prior to killing, all were injected with 20 muCi 45Ca/100 g body weight intraperitoneally. AsA restriction alone caused an 89% reduction in adrenal AsA concentration, but growth rate, adrenal weight and plasma ACTH were not different from those of pair-fed controls. Adrenal radiocalcium uptake, adrenal calcium content and plasma corticosteroids were similar in saline-treated guinea pigs restricted in AsA and the ACTH-treated controls, all of which were significantly higher than the values observed in saline-injected controls. Similar responses of the ACTH-treated controls and the saline-treated mildly deficient guinea pigs indicated that, at the adrenal AsA levels achieved (4.45 to 7.02 mg/100 g tissue), adrenal calcium and plasma corticosteroids increased significantly without the mediation of ACTH.     

Plasma vitamin A levels in cattle in response to large doses of vitamin A

A dose response procedure was developed for evaluating vitamin A status and utilization in cattle. This could be useful for evaluating diets, vitamin A stores and homeostatic control of vitamin A. Three experiments were designed to determine: 1) size of vitamin A dose required to increase plasma vitamin A concentrations; 2) time after dosing when plasma vitamin A concentrations peak, and 3) if changes in plasma vitamin A concentrations are useful in assessing dietary vitamin A utilization. Using twenty-four steers and heifers, the first two experiments showed that 30X or 40X daily vitamin A requirement (daily requirement calculated as X = body weight in kilograms times 55 International Units of vitamin A) given orally was sufficient to cause plasma vitamin A concentrations to rise 20 hours after dosing. Plasma vitamin A concentrations increased (P less than .01) from 57 to 81 micrograms/dl and 64 to 84 micrograms/dl after a 30X or 40X treatment, respectively. Twenty-X daily requirement resulted in a slight increase after 20 hours (P greater than .05). Seventy-two feedlot steers were used in experiment three to determine if diet affects vitamin A dose response. Variations in feed intake, monensin in the diet or a single dose of vitamin E did not cause significant changes in plasma vitamin A response to vitamin A dosage. Steers receiving monensin had higher initial plasma vitamin A concentrations, but no differences were observed after dosing. Results indicate that dose responses may be useful in assessing dietary vitamin A utilization.     

Plasma tocopherol concentrations in response to supplemental vitamin E

Normal healthy volunteers were studied after various doses of dl-alpha-tocopherol were ingested on different schedules. Administration of 440, 880, or 1320 mg (400, 800, or 1200 IU) of dl-alpha-tocopherol as a single dose resulted in elevation of plasma alpha-tocopherol concentrations that peaked at 12-24 h. Chronic administration of dl-alpha-tocopherol (440, 880, or 1320 mg/d for 28 d) resulted in a steady state that occurred by days 4-5 of supplementation. Discontinuation of the treatment after day 28 was associated with a decline of plasma alpha-tocopherol, which returned to the pretreatment concentrations between 12 and 20 d. The plasma elevation of alpha-tocopherol was affected by dietary fat intake. Individuals consuming a high-fat diet showed significantly greater plasma alpha-tocopherol concentrations as compared with those fed a low-fat diet. The results of this study indicate that plasma kinetics of alpha-tocopherol are similar when supplements of 440, 880, or 1320 mg dl-alpha-tocopherol are given to normal, healthy individuals.