Showing papers on "Low protein published in 1994"

Molecular Markers Associated with Maize Kernel Oil Concentration in an Illinois High Protein × Illinois Low Protein Cross

Abstract: The Illinois Long Term Selection Strains offer a unique opportunity to investigate the quantitative genetic basis of kernel chemical traits. This study was conducted to determine the number and magnitude of quantitative trait loci (QTL) influencing kernel oil concentration and kernel weight in a maize (Zea mays L.) population derived from a cross of Illinois High Protein (IHP) × Illinois Low Protein (ILP). The parental strains had been divergently selected for protein concentration for 76 cyles, yet varied in oil concentration from 29 g kg -1 (ILP) to 54g kg -1 (IHP) and in 300 kernel weight from 76.5g (ILP) to 41.1g (IHP) [...]

Increased systolic blood pressure in adult rats induced by fetal exposure to maternal low protein diets.

Abstract: 1. Possible associations between maternal nutrition in pregnancy and non-communicable diseases of adulthood were assessed using a rat model. Rats were habituated to diets containing a range of protein levels (18, 12, 9 and 6% by weight), over a 14 day period, before mating. The low protein diets were maintained throughout pregnancy. Lactating mothers and their offspring were transferred to a standard chow diet (20% protein). 2. Pregnant rats demonstrated a graded response to the diets, with those fed 9 and 6% protein tending to consume less energy and gain less weight than 18% protein fed controls. Litter size and newborn death rates were not significantly altered by the low protein diets. 3. Offspring of 12 and 9% protein fed dams were grossly normal, gaining weight at a similar rate to those born to 18% protein fed control rats. Offspring of the 6% protein fed dams were smaller than pups from all other groups, over a 21 week period. 4. At 9 weeks of age, systolic blood pressure was determined in the offspring. All offspring from the three low protein groups were found to have significantly elevated blood pressure (15-22 mmHg) relative to the control group. An inverse relationship between maternal protein intake and the systolic blood pressure of the offspring was observed. Blood pressure remained elevated in the offspring of the 9 and 6% protein fed dams until 21 weeks of age. The observed hypertension was associated with increased pulmonary angiotensin-converting enzyme activity in the low protein groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Laboratory diagnosis of APC-resistance: a critical evaluation of the test and the development of diagnostic criteria

Abstract: The APC-resistance test consists of two APTT's, one in the presence and one in the absence of a fixed amount of Activated Protein C (APC), and is a simple and reliable method to detect a reduced sensitivity to the anticoagulant action of APC (APC-resistance). At a fixed concentration of APC the prolongation of the APTT is dependent on the activator, the CaCl2 concentration, the citrate concentration in the sample, and on sample handling. The effect of sample handling can be reduced by calculating the APC-Sensitivity Ratio (APC-SR). The actual prolongation of the APTT is also influenced by low protein S levels (reduction of APC-SR) and by reduced levels of factors V, VIII and IX (increase of APC-SR). The APC-SR is most dramatically effected by reduced levels of factors II and X, which result often in "unmeasurable" APC-SR's in plasmas of patients on oral anticoagulant treatment. So at present no reliable APC-SR's can be measured in these patients. Patients treated with heparin can be tested after treatment of their plasma with Hepzym. The inter- and intra-assay variation in the APC-SR is 4% and 2%, respectively, when using the same batches of activator and APC. The variation which is introduced in the APC-SR by use of different batches of activator or APC, or by the use of different APC or CaCl2 concentrations, can effectively be avoided by expressing the result of the test in normalized-APC-SR (n-APC-SR).(ABSTRACT TRUNCATED AT 250 WORDS)

DNA looping by the HMG-box domains of HMG1 and modulation of DNA binding by the acidic C-terminal domain.

Abstract: We have compared HMG1 with the product of tryptic removal of its acidic C-terminal domain termed HMG3, which contains two 'HMG-box' DNA-binding domains. (i) HMG3 has a higher affinity for DNA than HMG1. (ii) Both HMG1 and HMG3 supercoil circular DNA in the presence of topoisomerase I. Supercoiling by HMG3 is the same at approximately 50 mM and approximately 150 mM ionic strength, as is its affinity for DNA, whereas supercoiling by HMG1 is less at 150 mM than at 50 mM ionic strength although its affinity for DNA is unchanged, showing that the acidic C-terminal tail represses supercoiling at the higher ionic strength. (iii) Electron microscopy shows that HMG3 at a low protein:DNA input ratio (1:1 w/w; r = 1), and HMG1 at a 6-fold higher ratio, cause looping of relaxed circular DNA at 150 mM ionic strength. Oligomeric protein 'beads' are apparent at the bases of the loops and at cross-overs of DNA duplexes. (iv) HMG3 at high input ratios (r = 6), but not HMG1, causes DNA compaction without distortion of the B-form. The two HMG-box domains of HMG1 are thus capable of manipulating DNA by looping, compaction and changes in topology. The acidic C-tail down-regulates these effects by modulation of the DNA-binding properties.

Quinolone antibacterials. An update of their pharmacology and therapeutic use.

Abstract: Quinolones are a class of antibiotics structurally related to nalidixic acid. They exhibit bactericidal activity primarily by inhibiting bacterial DNA gyrase. The early quinolones had a limited spectrum of activity, low potency, high frequency of spontaneous bacterial resistance, low serum drug concentrations and short half-lives, which virtually restricted their use to urinary tract infection. The new fluorinated quinolones differ from their predecessors in their broad antibacterial spectrum, including both Gram-negative and Gram-positive aerobic, and facultative anaerobic bacteria as well as many Mycobacterium spp., Chlamydia spp., Legionella spp. and Mycoplasma spp., in addition to many strains of bacteria that are multiresistant to beta-lactam antibiotics and aminoglycosides. They also exhibit high potency, a low incidence of resistance, high oral bioavailability, extensive tissue penetration, low protein binding and long elimination half-lives. They are generally well tolerated apart from some gastrointestinal disturbance and rashes, including photosensitive eruptions and a propensity to cause central nervous system excitation. Clinically important interactions include those with antacids, theophylline, fenbufen and warfarin. Potential toxic effects include cartilage damage, ocular toxicity, teratogenicity and impairment of spermatogenesis. The role of fluoroquinolones continues to widen, encompassing infections of the urinary tract, respiratory tract, skin and soft tissues, bone and joints, infections in immunocompromised patients, sexually transmitted diseases, infectious diarrhoea, gynaecological infections and surgical prophylaxis. The convenience of oral therapy is an added advantage of the new fluoroquinolones.

Biochemical composition and digestive enzyme activity in larvae and postlarvae ofPenaeus japonicus during herbivorous and carnivorous feeding

Abstract: The growth, survival, digestive enzyme activity and biochemical composition ofPenaeus japonicus (Bate) larvae and postlarvae were measured under three feeding regimes. Larvae were reared through the protozoeal stages usingChaetoceros gracilis. From the first mysis stage, three feeding regimes were used; (A)C. gracilis plusArtemia sp. nauplii, (B)Artemia sp. nauplii alone or (C)C. gracilis alone. No significant difference was found in growth, survival, protein content or lipid content of postlarvae from the treatments receiving the single-feed type, despite the low protein (7%) and highly unsaturated fatty acid content of the alga. Growth of larvae receiving the mixed diet was significantly higher than in the other treatments. Trypsin activity was more strongly influenced than amylase activity by dietary treatment, and differences in the ratio of these enzymes between treatments suggest independent control of their secretion. Trypsin activity recorded in larvae feeding onC. gracilis was up to six time higher than in larvae feeding onArtemia sp. nauplii, apparently in response to the low protein content of the alga. Larvae receiving the mixed diet exhibited an intermediate level of trypsin activity; it is suggested that the ingestion of algae is necessary for optimal assimilation of the zooplankton component of the diet.

The magnesium-insertion step of chlorophyll biosynthesis is a two-stage reaction.

Abstract: Mg(2+)-chelatase catalyses the first step unique to chlorophyll synthesis, namely the insertion of Mg2+ into protoporphyrin IX. When pea (Pisum sativum L., cv. Spring) chloroplasts are lysed in a buffer lacking Mg2+ and the thylakoids removed by centrifugation, the remaining mixture of light membranes and soluble proteins (LM/S) has high Mg(2+)-chelatase activity. Several lines of evidence are presented to show that the Mg2+ insertion catalysed by this preparation is a two-step reaction consisting of activation followed by Mg2+ chelation. An activated state of Mg(2+)-chelatase is achieved by preincubating LM/S with ATP. The activated state is observed as the elimination of the approx. 6 min lag in the rate of Mg2+ chelation on addition of the porphyrin substrate. The activity of LM/S assayed at low protein concentrations can be greatly enhanced by preincubating at high protein concentrations (12 mg/ml is optimal). This activation effect requires the presence of both LM and S fractions, as well as ATP. Both steps require ATP, but at different concentrations; the first step is optimal at > 0.5 mM (EC50 = 0.3 mM) and the second step is optimal at 0.3 mM (EC50

Low protein diets increase neuropeptide y gene expression in the basomedial hypothalamus of rats

Abstract: Food deprivation elevates both neuropeptide Y (NPY) gene expression in the basomedial hypothalamus and NPY levels in the paraventricular nucleus (PVN). To gain a better understanding of the dietary control of NPY, we systematically examined the effects of macronutrient restriction on the gene expression of NPY in the basomedial hypothalamus and NPY content in the PVN. Rats were fed one of eight different diets for 12 d. The control group was fed a modified AIN-76 diet. One group was fed the modified AIN-76 diet but was restricted in energy by 50%. Six isocaloric (to the control diet) test diets were prepared, each with an individual macronutrient reduced by 50%. Neuropeptide Y gene expression was elevated in protein-restricted animals as well as in energy-restricted animals. Carbohydrate or fat restriction seemed to have no effect on NPY gene expression. Though the NPY content in the PVN was not different between any groups, two findings were consistent with greater NPY release in protein-restricted animals. Animals fed a low protein diet were hyperphagic and had a greater amount of body fat. This study suggests that low levels of dietary protein may have a role in the regulation of NPY gene expression.

Sepsis modifies the contribution of different organs to whole-body protein synthesis in rats.

Abstract: 1. Protein synthesis rate was measured in the liver, muscle, intestine and whole body of septic rats and pair-fed controls by administration of a large dose of L-[U14C]valine. Sepsis was induced by intravenous injection of live bacteria, and protein synthesis measurements were carried out 48 h later. 2. Septic rats exhibited a reduction in food intake to between 10 and 50% of the normal level on the 2 days after infection. Animals lost body weight and the relative organ weight was increased in liver, unchanged in intestine and decreased in skeletal muscle. 3. The fractional protein synthesis rate of the whole body excluding liver was increased by 19% in septic rats in comparison with pair-fed controls, but the absolute protein synthesis rate was similar in the two groups because of the low protein content of the infected group. 4. The fractional protein synthesis was increased in whole intestine and liver but was decreased in skeletal muscle. In muscle and liver, the difference between infected and pair-fed animals was more pronounced for the absolute than for the fractional protein synthesis rate. In intestine, the fractional protein synthesis rate was similarly increased in whole intestine and the muscular layer of ileum. This suggests different regulation of protein synthesis in skeletal and smooth muscles. 5. The present investigation shows a complete redistribution of protein synthesis in sepsis. Liver represents about a third of the whole-body protein synthesis instead of 15% and becomes predominant over synthesis of muscle.

Growth and metabolism of gastrointestinal and skeletal muscle tissues in protein-malnourished neonatal pigs

Abstract: Our objective was to determine whether neonates adapt to protein malnutrition by preserving the relative growth and metabolism of gastrointestinal tissue at the expense of skeletal muscle. We measured gastrointestinal, liver, and carcass tissue masses and blood flow, oxygen consumption, and net glucose and amino acid fluxes in vivo of the portal-drained visceral tissues (PDV) in neonatal pigs fed isocaloric diets containing either 30% protein [control (C)] or 15% [low protein (LP)] for 14 days. Relative protein mass and fasting blood flow and oxygen consumption of PDV tissue in either group were not different. Relative protein mass of liver and carcass was lower in LP pigs. Net essential amino acid absorption and insulin concentration after feeding were lower in LP pigs. Results demonstrate that protein malnutrition in neonatal pigs differentially altered rates of tissue growth, such that the proportion of body protein partitioned into gastrointestinal tissue was preserved, while that of skeletal muscle was reduced. Chronic reduction in amino acid absorption in protein-malnourished pigs resulted in a reduced insulin response to feeding, which presumably limited substrate availability and the anabolic stimulus for skeletal muscle protein accretion.

The effect of protein intake on boar libido, semen characteristics, and plasma hormone concentrations.

Abstract: To determine the effect of low protein intake on boar libido, semen characteristics, and plasma hormone concentrations, 20 crossbred boars (1 yr of age) were divided into 10 littermate pairs, and boars from within pairs were fed 44 g/kg of BW.75 per day of either a low-protein diet (7% CP) or a control diet (16% CP) with the same energy content (3.41 Mcal of ME/kg). During the first 16 wk and from wk 19 to 23, semen was collected two times per week. During wk 17 and 18, boars were subdivided within dietary treatment and semen was collected either two or seven times per week. Blood samples were collected at 12-min intervals for 6 h before and 1 h after an intravenous injection of GnRH (375 ng/kg of BW) during wk 24. All plasma samples were analyzed for LH and pooled samples were analyzed for estradiol-17 beta and testosterone. Boars with low protein intakes required more time to start ejaculation (P = .11, wk 0 through 7; P .39) for any of the semen or libido measurements. Testosterone and LH concentrations were not affected by protein intake (P > .5). However, concentration of estradiol-17 beta was greater in boars fed the control diet than in boars fed the low-protein diet (582 vs 202 pg/mL, respectively; P < .08). Estrogen concentrations in boars were negatively correlated with the time required for the boar to start ejaculating (r2 = .72). Boars with low protein intakes had reduced libido and semen volume. This reduction in libido and semen volume may be a result of a decrease in estradiol-17 beta concentration in circulation.

The acute phase response of adult rats is altered by in utero exposure to maternal low protein diets.

Abstract: The immune system has been previously demonstrated to be under the influence of maternal nutrition in pregnancy. Assessment was made of the effects of low protein diets (12, 9 and 6 g casein/100 g diet) fed before conception and during pregnancy on the immune system of the resulting offspring in early adulthood. Control animals were fed a diet containing 18 g casein/100 g. At the end of pregnancy all dams were fed a nonpurified diet containing 18.3 g protein/100 g. Male pups were weaned onto this diet, which they consumed until the age of 7 wk. Rats exposed to 18 g casein/100 g diet in utero mounted a typical acute phase response following E. coli endotoxin challenge at age 7 wk. Food intake was 75% lower, hepatic zinc concentrations 25% greater, and serum albumin 15% lower than in saline-injected controls. Pulmonary glutathione levels were 35% greater in endotoxin-treated rats than in saline-treated controls. In rats exposed to low protein diets in utero the trend was for the acute phase response to be blunted. This was most noticeable with respect to the anorectic response, hepatic zinc uptake and pulmonary glutathione uptake. In rats not challenged with endotoxin, maternal diet had pronounced effects on tissue zinc status at the age of 7 wk. Liver zinc concentrations were 21% and 16% lower in the groups exposed to 9 and 6 g casein/100 g diets relative to the control group exposed to 18 g casein/100 g diet. Glutathione status was altered in all groups exposed to low dietary protein in utero.(ABSTRACT TRUNCATED AT 250 WORDS)

Cysteine and Methionine Supplementation Modulate the Effect of Tumor Necrosis Factor α on Protein Synthesis, Glutathione and Zinc Concentration of Liver and Lung in Rats Fed a Low Protein Diet

Abstract: The synthesis of cysteine-rich compounds such as glutathione and metallothionein is an integral part of the response to cytokines. To examine the essentiality of an adequate supply of sulfur amino acids during a response to tumor necrosis factor alpha (TNF) we fed rats a low protein (8% casein) diet supplemented with either cysteine and alanine, methionine and alanine, or alanine alone, or a normal protein (20% casein) diet for 8 d before injection with TNF or saline. Those animals injected with saline were pair-fed the intake of their TNF-injected counterparts for the 24 h after injection. In a second experiment, control groups fed the same diets but receiving no treatment were also examined to establish baseline values. Although few significant differences between the non-injected animals consuming food ad libitum were apparent, TNF injection and pair-feeding resulted in differences between the dietary groups. Supplementation of the low protein diet with either cysteine or methionine improved growth and increased liver and lung glutathione concentration, zinc concentration, protein concentration and protein synthesis compared with results for the alanine-supplemented group. Lung polymorphonuclear cells were proportionally elevated in the TNF-treated, alanine-supplemented group compared with the other dietary groups treated with TNF. The changes in protein synthesis and glutathione concentration of the liver in response to TNF showed that sulfur amino acids may be partitioned to a greater extent into hepatic protein than into glutathione when sulfur amino acid intake is low. Consequently the adequacy of dietary sulfur amino acids will determine the extent to which antioxidant defenses are maintained during inflammation.

Digestibility of energy, protein, fat and non-starch polysaccharides in mixed diets: comparative studies between man and the rat.

Abstract: The apparent digestibility of energy, protein, fat and non-starch polysaccharides (NSP) of low and high dietary fibre (DF) mixed diets were studied in three series of experiments with man and the rat. Low DF diets were used as control diets in each experimental series and the DF level was increased by adding fruits and vegetables (Study 1), citrus fibre concentrate (Study 2) and insoluble barley fibre (Study 3), In Study 3 the high DF diet was fed at two protein levels. There was in most cases good agreement between the digestibility of energy between man and the rat, with the digestibility of energy of the low DF control diets of 0.941–0.950 in man compared with 0.933–0.952 in the rat and of the high DF diets of 0.897–0.931 in man and 0.865–0.920 in the rat. The biggest difference in digestible energy between the two species was found for the diet enriched with fruits and vegetables (0.032 absolute units) and citrus fibre concentrate (0.025 absolute units). Apparent digestibility of protein was slightly lower in man than in the rat for all diets in Studies 1 and 2. In Study 3, however, apparent digestibility of protein was consistently lower in man than in the rat with differences in absolute digestibilities between the two species varying from 0.023 (high DF/high protein) to 0.071 (high DF/low protein). The digestibility of fat was the same in man and in the rat in all but the high DF diet of Study 2. The rat appears to have a lower capacity to digest fibre polysaccharides than man and the digestibility of NSP was consistently lower in the rat than in man. The biggest difference between the two species was found for the diets in Study 2 where the digestibility of NSP in man was measured to be 0.774–0.885 compared with only 0.501–0.517 in the rat. For the other diets the differences in NSP digestibility were 0.077–0.137 absolute units. In spite of some differences between man and the rat in their ability to digest nutrients the various diets are ranked in the same order by the two species.

Dietary protein and growth in infants with chronic renal insufficiency: a report from the Southwest Pediatric Nephrology Study Group and the University of California, San Francisco.

Abstract: This report describes growth and nutrition data from the feasibility phase of a clinical trial that was designed to evaluate the effect of diet protein modification in infants with chronic renal insufficiency (CRI). The purpose of the proposed trial was to compare the safety (effect on growth in length) and efficacy [effect on glomerular filtration rate (GFR)] of a diet with a low protein:energy (P∶E) ratio versus a control diet in such patients. Twenty-four infants with GFRs less than 55 ml/min per 1.73 m2 were randomly assigned at 8 months of age to receive either a low-protein (P∶E ratio 5.6%) or control protein (P∶E ratio 10.4%) formula, which resulted in average protein intakes of 1.4 and 2.4 g/kg per day in the low and control groups, respectively. Overall energy intakes over a 10-month period of study averaged 92%±12% recommended dietary allowance (RDA) for length in the low-protein group and 92±15% RDA in the control group. Weight for age standard deviation scores (SDS) were comparably low in both groups at the time of randomization (low-protein —2.0±1.3, control −1.9±1.1) and at the end of the study (low −1.9±1.2, control −1.7±0.9). Length for age SDS at entry tended to be lower in the low-protein group but were not significantly different in the two groups (low −2.2±1.4 vs. control −1.7±1.4). However, at 18 months the low-protein group had a significantly lower SDS for length (−2.6±1.2 vs. −1.7±1.4). The length velocity SDS from 12 to 18 months were also different, with the low-protein group remaining strongly negative (−1.0±0.9) while the control group improved (−0.1±1.1). We conclude from this feasibility study that there is a need for caution in advising the use of low-protein intake in infants with CRI. However, our findings should be regarded as preliminary because of the small number of patients and the observation that the weight gains were the same in the two groups.