The effects of intraruminal infusions of urea, casein, glucose syrup and a mixture of casein and glucose syrup on nitrogen digestion in the rumen of cattle receiving grass-silage diets

In an incomplete 5 X 5 Latin square experiment, four cattle were given grass silage in two meals per d to satisfy 1.15 maintenance energy requirements. In addition, water or casein (21 g nitrogen and 0.17 kg organic matter (OM)/d) or urea (U; 28 g N/d) or a glucose syrup (G; 0.87 kg OM/d) or casein and glucose syrup (CG; 17 g N and 0.93 kg OM/d) were infused intraruminally at a constant rate. A 24 h collection of duodenal digesta was made using chromic oxide for flow estimation and 35S as a marker of microbial N entering the small intestine. Samples of rumen fluid were also taken for estimation of rumen pH, and concentrations of ammonia-N and volatile fatty acids. The intraruminal infusions had no significant effects on rumen pH, concentrations of volatile fatty acids or their molar proportions. Infusion of either C or U significantly (P less than 0.05) increased rumen NH3-N concentrations whereas infusions of either G or CG lowered rumen NH3-N concentrations. Infusions of C or U had no significant effect on the quantities of OM, acid-detergent fibre (ADF) or N constituents which entered the small intestine. Infusions of G or CG increased the quantities of OM (G P less than 0.05, CG P less than 0.01), ADF (CG P less than 0.05), non-NH3-N (G P less than 0.05, CG P less than 0.01), amino acid N (G P less than 0.05, CG P less than 0.01) and microbial N (G P less than 0.05, CG P less than 0.01) which entered the small intestine. The efficiency of rumen microbial N synthesis was unchanged by the infusion of C, U or G (P greater than 0.05) but increased significantly (P less than 0.05) when CG were infused.     

Acute effects of exposure to hexanal vapors in humans

OBJECTIVE: n-Hexanal is a major component in emissions from stored wood pellets. The production and use of wood pellets has increased dramatically. Our aim was to evaluate acute health effects of n-hexanal vapors. METHODS: Twelve healthy volunteers were exposed to 0, 2, and 10 ppm n-hexanal for 2 hours at rest in a balanced order. RESULTS: Ratings of discomfort in the eyes and nose, solvent smell, and headache increased significantly with the level of exposure. Frequency of blinking was significantly increased at 10 ppm. No effects on pulmonary function and nasal swelling were detected, except a not-significant tendency to increased nasal obstruction at 10 ppm. No clear effects on plasma inflammatory markers (C-reactive protein and interleukin-6) were observed. CONCLUSIONS: Two hours of exposure to n-hexanal results in mild irritation at 10 ppm, with no apparent adversity at 2 ppm.     

Effect of voluntary exercise on physiological function and feeding behavior of mice on a 20% casein diet or a 10% casein diet.

The effects of voluntary exercise on growth and food intake, body composition, organ weight, and fatty acid composition of adipose tissue of mice fed on a 20% casein diet or a 10% casein diet were examined. The weight gain was greater for the 20% casein nonexercise group (20% NE) than that for the 20% casein exercise group (20% E), 10% casein exercise group (10% E) and 10% casein nonexercise group (10% NE). There were no significant differences between the groups except the 20% NE. In 20% E and 10% E, body fats decreased markedly. On the other hand, a very high ratio of protein was present in the body composition of both groups. In the 20% and 10% casein diet groups, food intake was increased by voluntary exercise, but there was no significant difference between 10%E and 10% NE except occasional periods during these experiments. After 6 weeks of age, 10% E had a tendency to undertake more voluntary exercise than 20% E, though the difference was not statistically significant. Development of the heart and gastrocnemius muscles was accelerated by voluntary exercise and epididymal fat tissue was markedly decreased.     

The initial physiological responses to glucose ingestion in normal subjects are modified by a 3 d high-fat diet

The present study was designed to investigate whether 3 d of high-fat, low-carbohydrate diet (with normal daily energy intake) affected the metabolic, cardiovascular and thermic responses to an oral glucose load (1.5 g/kg body-weight). Eight normal weight, healthy subjects (five male) consumed diets containing approximately 65% by energy of carbohydrate (C) or fat (F), each for 3 d. Before and after glucose ingestion, continuous recordings of oxygen consumption and carbon dioxide production were made using indirect calorimetry, and metabolic rate (MR) and respiratory exchange ratio (RER) were calculated. Heart rate, blood pressure and limb blood flow were also measured. There was no significant change in baseline MR following the high-fat diet, but the fasting RER was reduced. The high-fat diet modified the responses to oral glucose, with a greater increase in MR (kJ/min; C + 0.38, F +0.76), and an enhanced plasma insulin response (mU/l; C + 51.5, F + 85.0). There were no differences between the two diets with respect to the baseline blood glucose levels or the changes after glucose ingestion. Heart rate, systolic and diastolic blood pressures and blood flow responses to the glucose load were similar after the two diets. There was no plasma catecholamine response to glucose ingestion. It can be concluded that a high-fat diet alters the initial thermic response and insulin response but does not alter the other physiological responses to glucose ingestion.     

Nutritional effects of marijuana, heroin, cocaine, and nicotine

Use of addictive drugs, such as cocaine, marijuana, and nicotine, affects food and liquid intake behavior, taste preference, and body weight. Changes in specific nutrient status and metabolism can also develop; heroin addiction can cause hyperkalemia and morphine use can result in calcium inhibition. Nutrition-related physiological aspects, such as impaired gastrin release, hypercholesterolemia, hypothermia, and hyperthermia, are also seen with morphine use. Nutrition-related conditions can affect sensitivity to and dependence on drugs and their effects. Diabetes decreases sensitivity to and dependence on morphine, protein deprivation produces preferential fat utilization with low cocaine use, and vitamin D deficiency decelerates morphine dependency. During use and/or withdrawal from nicotine, heroin, marijuana, and cocaine, major changes in food selection and intake occur, which result in weight gain or loss. Detailed human studies are needed to investigate the effects of drug use on the broad spectrum of nutrients and to determine the role of nutrition during drug withdrawal.     

Digestibility of casein, formaldehyde-treated casein and soya-bean protein in relation to their effects on serum cholesterol in rabbits

Adult male rabbits were fed on semi-purified diets containing soya-bean protein isolate, casein or formaldehyde-treated casein as the protein source and 1 g cholesterol and 5 g of the non-absorbable marker chronic oxide/kg diet. The concentration of cholesterol in serum and in liver was increased on both the casein and formaldehyde-treated-casein diets. Excretion of bile acids and their concentration in faeces were lower in rabbits fed on casein or formaldehyde-treated casein when compared with rabbits fed on soya-bean protein. Apparent digestibility of nitrogen was lowest when formaldehyde-treated casein was fed, and highest on the casein diet. In rabbits fed on casein treated with formaldehyde, higher proportions of N were found in the water-soluble and trichloroacetic acid-insoluble protein fractions of the gastrointestinal tract contents compared with rabbits on the other two diets. Absorption of phosphate from the gastrointestinal tract was higher in rabbits fed on casein than in rabbits fed on soya-bean protein or formaldehyde-treated casein. The results indicate that, in rabbits, protein digestibility may not be an important determinant of serum cholesterol.     

Some effects, in baboons, of chronic ingestion of glycerol with sucrose or glucose.

Six mature male and six mature female baboons were given fat-free diets high in sucrose or glucose together with glycerol, a chow diet with glycerol, and a fat-free high sucrose diet without glycerol. In the male animals, the concentration of triglyceride, cholesterol, glucose, and glycerol in fasting serum was significantly greater when sucrose and glycerol were given together compared with the other diets. The fasting serum triglyceride and cholesterol were significantly greater in the females on the sucrose + glycerol diet compared to the glucose + glycerol diet. It is suggested that glycerol and fructose (in sucrose) share a metabolic pathway that leads to an enhancement of serum lipid concentrations.     

Prolonged consumption by infants of wheat-based diets with and without casein or lysine supplementation

Infants consumed 75% of calories as 82% extraction wheat flour with satisfactory short-term protein and energy digestion. Protein needs, represented by N retentions from casein, probably were not satisfied. Long-term (3+ months) studies in four infants showed that 50% calories and 80% protein from wheat (casein added to 8% protein calories) supported weight gain and linear growth more than expected. Prolonged feeding of 75% calories and 100% protein from wheat attempted in three infants. In the oldest (15.5 months), digestibility and growth was satisfactory; in one, despite good digestion, weight gain and growth was inadequate and serum albumin fell until 0.2% lysine was added; and in another, weight gain was satisfactory but albumin fell to 3.25 g/dl and growth was inadequate. In six other infants, lysine addition during the 2nd of 3 months was associated with significant increase in N retention and weight gain and stabilization of albumin; lysine withdrawal resulted in significant decrease in weight gain with no effect on N retention or albumin; growth was barely adequate during 3-month study. Serum cholesterol fell only when dietary protein was inadequate. It is practically impossible for unsupplemented wheat to satisfy protein needs of infants and most small children.     

Preexercise feedings of glucose, fructose or sucrose: effects on substrate depletion in rats

Male Wistar rats (n = 72) trained to run on a treadmill were fasted overnight and fed by gavage 3 ml unsupplemented water or a solution containing 2 g of glucose, fructose or sucrose 30 min prior to exercise. Six rats from each dietary group were killed after 0, 1 or 2 h of exercise. Blood glucose levels decreased in all groups over the 2-h exercise period; however, the largest decline in blood glucose was exhibited by the rats fed unsupplemented water (-32.1%), followed by those fed fructose (-26.9%), sucrose (-13.9%) and glucose (-8.3%). The water-fed control rats also had the largest increase in circulating free fatty acids (+215.4%), followed by those fed fructose (+120.8%), sucrose (+69.2%) and glucose (+57.5%). The fructose-fed animals exhibited the greatest depletion of liver glycogen and the smallest decline in soleus and red vastus lateralis muscle glycogen of the rats fed the different carbohydrates. The data indicate that exercise-induced changes in substrate levels can be modified by the type of carbohydrate given prior to exercise.     

Nutritional recovery with okara diet prevented hypercholesterolemia,hepatic steatosis and glucose intolerance

We assessed the biological value of an okara diet and its effects on the hormonal and metabolic profile of rats submitted to protein restriction during intra-uterine life and lactation and recovered after weaning. Male rats from mothers fed either 17% or 6% protein during pregnancy and lactation were maintained on 17% casein (CC, LC), 17% okara (CO, LO) or 6% casein (LL) diets over 60 d. The nutritional quality of the okara protein was similar to that of casein. The okara diet was effective in the nutritional recovery of rats in growing that were malnourished in early life. Furthermore, the okara diet reversed the hypercholesterolemia and the hepatic steatosis observed in the malnutrition and prevented glucose intolerance in an animal model prone to diabetes mellitus.     

Human-milk proteins: analysis of casein and casein subunits by anion-exchange chromatography, gel electrophoresis, and specific staining methods.

Casein in human milk is believed to serve several biological functions in newborns. However, the content and subunit composition of human casein has so far received little attention. We recently developed a method to separate human-milk whey and casein by adjustment of whole human milk to pH 4.3 and addition of calcium followed by ultracentrifugation. In this study we analyzed and evaluated human casein prepared by different methods. We used fast protein liquid chromatography (FPLC) with an anion-exchange column (Mono-Q) and polyacrylamide gradient gel electrophoresis techniques to analyze the casein subunit composition. Total casein in human milk, as determined by the Kjeldahl method, varies during lactation; the casein content is approximately 20% of the total protein content in early lactation and 45% in late lactation. We found differences in both glycosylation and phosphorylation patterns of kappa-caseins and beta-caseins from premature and term milk samples.     

妊娠期糖尿病和糖耐量减低的营养治疗研究

目的:研究营养治疗对妊娠期糖尿病(GDM)和糖耐量减低(IGT)的意义.方法:对来我院围产检查并分娩的610例孕妇,采用50 g葡萄糖负荷试验(GCT)筛查,阳性者再行口服葡萄糖耐量试验(OGTT),以诊断GDM和IGT;对于GDM和IGT进行严格饮食控制,监测其空腹和餐后2 h血糖变化情况,并跟踪其围生期病死率、巨大儿和新生儿患病率情况.结果:50 g GCT阳性者140例,其中确诊为GDM 15例,IGT 61例;饮食控制后GDM组空腹和餐后2 h血糖均有明显下降(P＜0.05);IGT组餐后2 h血糖有明显下降(P＜0.05).两组的围生期病死率、巨大儿和新生儿患病率均低于国内相关文献报道,其中IGT组的巨大儿和新生儿患病率均低于GDM组(P＜0.05).结论:对所有孕妇应做50 g GCT筛查;严格合理的饮食控制对GDM和IGT的血糖控制和妊娠结局具有重要意义.     

Effects on plasma insulin of intermittent infusions of propionic acid, glucose or casein into the alimentary tract of non-lactating cows maintained on a liquid diet

1. An experiment was conducted using three non-lactating cows completely maintained by infusions of volatile fatty acids into the rumen, and casein into the abomasum. Plasma insulin responses to propionic acid, glucose or casein were recorded. Further information was obtained using protein-free infusions. 2. When part of the propionic acid was infused into the rumen in a twice-daily 3 h dose and the remainder infused continuously with acetic and butyric acids and casein, there were large increases in the concentrations of propionic acid and insulin in the jugular blood. When glucose, corresponding in energy to that supplied by the intermittent propionic acid infusions was similarly infused, the plasma levels of glucose and insulin were increased. Glucose appeared to stimulate a greater increase in insulin than did propionic acid. Casein infused into the abomasum in intermittent doses produced a rise in plasma insulin, but smaller than that observed with propionic acid or with glucose. 3. The protein-free infusion was characterized by a lower concentration of insulin in the blood plasma, a reduction in plasma urea and free amino nitrogen and unchanged plasma glucose.