Showing papers on "Low protein published in 1989"

Equilibrium dissociation and unfolding of the arc repressor dimer

Abstract: The equilibrium unfolding reaction of Arc repressor, a dimeric DNA binding protein encoded by bacteriophage P22, can be monitored by fluorescence or circular dichroism changes. The stability of Arc is concentration dependent, and the unfolding reaction is well described as a two-state transition from folded dimer to unfolded monomer. The stability of the protein is decreased at low pH and increased by high salt concentration. The salt dependence suggests that two ions bind preferentially to the folded protein. In 10 mM potassium phosphate (pH 7.3) and 100 mM KCl, the unfolding free energy reaches a maximum near room temperature. The results suggest that at the low protein concentrations where operator DNA binding is normally measured, Arc is predominantly monomeric and unfolded.

Apparent digestibility of feedstuffs by the marine shrimp Penaeus vannamei Boone

Abstract: The apparent dry matter digestibility (ADMD), apparent protein digestibility (APD), and apparent amino acid digestibility (AAAD) of thirteen feedstuffs used for marine shrimp diets were determined for the marine shrimp, Penaeus vannamei. The feedstuffs evaluated were casein, corn starch, gelatin, soy protein, wheat gluten, fish meal, rice bran, shrimp meal, soybean meal, squid meal, cellulose, chitin, and diatomaceous sand. Each feedstuff comprised 88% of the experimental diets. The ADMD values ranged from 91.4% to -21.4%. The purified feedstuffs were more efficiently digested than the practical feedstuffs. The dietary fillers (cellulose, chitin, and diatomaceous sand) were either poorly digested or not digested.The APD values ranged from 99.1% to 3.0%. There were no differences in APD due to animal or plant feedstuff origin. The AAAD were determined for arginine, lysine, leucine, isoleucine, threonine, valine, histidine, phenylalanine, glutamate, aspartate, glycine, proline, serine, tryrosine, and alanine. The digestibility trends observed for APD were similar for AAAD. The high AAAD for chitin suggested that the low APD was due to the low digestibility of the amine fraction of the chitin structure and not a low protein digestibility. Arginine, lysine, and glutamate were most efficiently digested, while alanine had the lowest apparent digestibility value.

A balanced diet as a goal for grazing: the food of the Manyara buffalo

Abstract: SUMMARY The diet of African buffalo Syncerus coffer (Sparrman) was studied in Lake Manyara National Park, northern Tanzania, in conjunction with production, consumption and protein concentration of the major food plants. Production and relative growth rates of leaves of Cynodon dactylon (L.) Pers., Cynodon plectostachyus (K. Schum.) Pilg. and Sporobolus spicatus (Vahl) Kunth were generally highest during the short rains, lower during the long rains and negligible during the long dry season. The grass Chloris gayana Kunth showed its peak in production and consumption in the dry season. The concentration of crude protein in the green leaves reflected this pattern of growth and was highest during periods of vigorous growth. Green leaves always had a higher crude protein concentration than green stalk, and green parts than dead parts. Cyperus laevigatus L. did not show marked seasonality in its production pattern or in the crude protein concentration in its green parts. The diet, as determined through faecal analyses, reflected grass species high in protein, except during the dry season when the buffalo concentrated on the sedge, which had a low protein concentration but which offered a dense sward enabling them to collect sufficient food. The concentration of crude protein in the diet was determined through faecal nitrogen determination. The quality of the diet showed a clear seasonality, at the end of the dry season approaching the minimum requirements for maintenance. The crude protein concentration showed that the buffalo consumed a combination of species and species parts, so that they ingested a balanced diet with regard to their requirements for protein and energy. Resume On a etudie le regime alimentaire du buffle africain Syncerus coffer au Pre National du Lac Manyara, en Tanzanie du Nord, en rapport avec la production, la consommation et la concentration en proteines des principales plantes alimentaires. La production et le taux de croissance relatif des feuilles de Cynodon dactylon, C. plectostachyus et Sporobolus spicatus sont generalement les plus eleves durant la petite saison des pluies, plus faibles durant la grande saison des pluies et negligeables durant la grande saison seche. La production et la consommation de la graminee Chloris gayana sont maximales durant la saison seche. La concentration de proteines brutes dans les feuilles vertes reflete ce mode de croissance et est la plus elevee durant les periodes de croissance vigoureuse. Les feuilles vertes ont toujours une concentration de proteines brutes plus elevee que la tige, et les parties vertes plus elevee que les parties mortes. On n'a pas releve de saisonnalite marquee dans le mode de production ou la concentration en proteines brutes dans les parties vertes de Cyprus laevigatus. Le regime alimentaire, etabli par analyses fecales, reflete la presence d'especes de graminees riches en proteines, sauf durant la saison seche lorsque le buffle se concentre sur les laiches; celles-ci ont une concentration faible en proteines mais constituent une pelouse dense lui permettant de consommer suffisamment de nourriture. La concentration en proteines brutes dans le regime alimentaire fut determine par identification de l'azote fecal. La qualite du regime alimentaire presente une saisonaliteevidente; a la fin de la saison seche elle est proche du niveau d'exigence minimal pour la survie. La concentration en proteines brutes montre que le buffle consomme une combinaison d'especes et de parties de plantes telle que le regime ingere est equilibre en ce qui concerne les exigencies proteiniques et energetiques.

NMR studies of body fluids.

Abstract: High resolution, high frequency, in vitro, proton NMR spectra of various body fluids, including urine, sweat, aqueous humour, amniotic fluid, seminal plasma, cerebrospinal fluid, synovial fluid and blood plasma are described and discussed. Applications include the detection of metabolic disorders, investigations of the biochemical basis of drug and xenobiotic metabolism, organ damage, and diagnoses for sick babies. The determination of metabolite concentrations is straightforward for fluids with a low protein content such as urine. In fluids with a high protein content such as blood plasma, it is possible to detect not only small molecules but also mobile regions of macromolecules, and to demonstrate the interaction of anions such as lactate with proteins. It seems likely that these methods will soon become established in modern pathology laboratories.

Dietary Protein Restriction Decreases Insulin-Like Growth Factor I Independent of Insulin and Liver Growth Hormone Binding*

Abstract: To determine the role of hypoinsulinemia and liver somatogenic (GH) receptors in growth retardation and decreased serum insulin-like growth factor I (IGF-I) levels during protein restriction, we have used a rat model where the effects of a low protein intake on body weight (BW), serum IGF-I concentration, and liver GH binding could be evaluated in the presence of low or high insulin concentrations. Two days after being made diabetic with streptozotocin (60 mg/kg BW), 6-week-old female rats (nine per group) were begun on a low (5%) or normal (15%) protein diet, without or with insulin supplementation (3 U lente daily). Nondiabetic rats fed both diets were used as controls (nine per group). In the nondiabetic animals, 7 days of protein restriction reduced BW gain by 50% (P less than 0.001), serum insulin by 44% (P less than 0.025), and serum IGF-I concentrations by 28% (P less than 0.001) without significantly changing liver GH binding. By day 9, BW was decreased in the diabetic animals by 12%, serum insulin by 80%, serum IGF-I by 55%, and liver GH binding by 62%; these effects were similar in the 5% and 15% protein-fed rats (P less than 0.001 vs. the corresponding controls). In the diabetes fed the normal diet, insulin treatment restored BW gain, serum IGF-I, and liver GH binding to normal values. In contrast, in the diabetics fed a protein-restricted diet and treated with insulin, BW gain and serum IGF-I concentrations remained low, similar to those in the malnourished controls. This diet-induced growth attenuation was observed despite high circulating insulin (2-3 times normal values), appropriate glucose control (63 +/- 9 mg/dl), and near restoration of liver GH binding. We conclude that while both protein restriction and diabetes attenuate growth and reduce IGF-I concentrations, the effects of protein restriction are independent of the effects of insulin and probably act by alteration of postreceptor mechanisms.

Regulation of the corpus luteum by protein kinase C. I. Phosphorylation activity and steroidogenic action in large and small ovine luteal cells.

Abstract: The activity and steroidogenic action of protein kinase C were evaluated in small and large steroidogenic ovine luteal cells. Protein kinase C activity (per mg protein) was threefold greater in large than in small luteal cells, whereas protein kinase A activity was similar in the two cell types. Phorbol 12-myristate 13-acetate (PMA) activated protein kinase C in luteal cells as demonstrated by membrane association of 91% of available protein kinase C within 15 min of PMA treatment. Longer treatments with PMA produced cells with low protein kinase C activity (protein kinase C-deficient cells) but did not affect cellular viability or protein kinase A activity. Activation of protein kinase C caused an acute, dose-dependent inhibition of progesterone production in unstimulated large and luteinizing hormone (LH)-stimulated small luteal cells. This inhibition by PMA appeared to be specific for protein kinase C since it was greatly attenuated in protein kinase C-deficient cells and since an inactive phorbol ester, 4 alpha-phorbol, had no effect on luteal progesterone production. The inhibitory locus of protein kinase C action in small luteal cells appeared to be distal to the adenylate cyclase enzyme because progesterone production was inhibited similarly in cells stimulated with LH, forskolin, or dibutyryl cyclic adenosine 3',5'-monophosphate. Cholesterol side-chain cleavage activity, as measured by metabolism of 25-hydroxycholesterol, was inhibited by PMA in large, but not in small, luteal cells. These data indicate that activation of protein kinase C specifically inhibits progesterone production in both large and small ovine luteal cells, although the intracellular mechanisms invoked appear to differ in the two cell types.

The effects of gastric pH and food on the pharmacokinetics of a new oral cephalosporin, cefpodoxime proxetil.

Abstract: The effects of alteration of gastric pH and food on the pharmacokinetics of 200 mg doses of cefpodoxime proxetil tablets were studied in two separate randomized, open label, crossover studies in healthy subjects In the pH study (n = 17 subjects), there was a lead-in period done under fasting conditions, followed by randomization to a four-way crossover of pentagastrin (6 micrograms/kg, subcutaneously), ranitidine (150 mg orally, 10 and 2 hours before dosing with the antibiotic), sodium bicarbonate (126 gm), or aluminum hydroxide (120 cc) Gastric pH was determined by nasogastric aspirates before and 10 minutes after the intervention, just before the antibiotic was given Peak plasma concentrations (Cmax) and area under plasma concentration-time curve (AUC) were highest in fasting and pentagastrin periods and were 35% to 50% lower for all of the other periods (p less than 00001) Gastric pH and Cmax and AUC were inversely related (r = 066 and r = 062; p less than 00001 for both) In the food study (n = 16 subjects), there were two lead-in periods, one done while subjects were fasting and one while they were normal diet, followed by randomization to a four-way crossover of either high or low protein diets, or high or low fat diets There were six meals in each diet Dosing with the antibiotic was done at the midpoint of the fourth meal Cmax and AUC were 22% to 34% higher for all diets than for the fasting period (p less than 00001), whereas the time to Cmax was unchanged These studies demonstrated that absorption of cefpodoxime proxetil is best at low gastric pH or in the presence of food, which suggests that the role of gastrointestinal function on the pharmacokinetic profile is complex

Reduction of Serum Insulin-like Growth Factor-I by Dietary Protein Restriction Is Age Dependent

Abstract: We have determined if dietary protein restriction for 1 wk has differential effects on growth, serum IGF-I, and liver growth hormone receptors at various stages of development. Female Wistar rats were fed a low (5%) protein diet for 7 d at 3, 4, 6, 8, and 12 wk of age, whereas controls were maintained on a normal (15%) protein diet. Body wt gain was impaired in the groups fed the low protein diet, despite normal energy intake, and the effect was attenuated with age. Liver cell number (DNA content) was reduced by low protein feeding in the 3-, 4-, and 6-wk age groups (p less than 0.01), but not in the older animals. Protein restriction caused a dramatic decrease in serum IGF-I in the younger animals (90 and 82% reduction versus normal fed age-matched controls, at 3 and 4 wk, respectively; p less than 0.001), and this effect was progressively attenuated with increasing age (49, 40, and 25% reductions of serum IGF-I at 6, 8, and 12 wk, respectively). Changes in serum IGF-I correlated with those of liver cell number (r = 0.80; p less than 0.001). Total and free liver growth hormone receptors were slightly decreased in the low protein diet groups at 4 (p less than 0.05) and 6 wk (total: p less than 0.001; free: p less than 0.01) but not in the other age groups. The occurrence of profound diet induced reductions in IGF-I without proportional reductions in liver GH receptors suggest that the apparent GH resistance occurs at a postreceptor level.(ABSTRACT TRUNCATED AT 250 WORDS)

Transcriptional switching by the MerR protein: activation and repression mutants implicate distinct DNA and mercury(II) binding domains.

Abstract: Bacterial resistance to mercuric compounds is controlled by the MerR metalloregulatory protein. The MerR protein functions as both a transcriptional repressor and a mercuric ion dependent transcriptional activator. Chemical mutagenesis of the cloned merR structural gene has led to the identification of mutant proteins that are specifically deficient in transcriptional repression, activation, or both. Five mutant proteins have been overproduced, purified to homogeneity, and assayed for ability to dimerize, bind mer operator DNA, and bind mercuric ion. A mutation in the recognition helix of a proposed helix-turn-helix DNA binding motif (E22K) yields protein deficient in both activation and repression in vivo (a-r-) and deficient in operator binding in vitro. In contrast, mutations in three of the four MerR cysteine residues are repression competent but activation deficient (a-r+) in vivo. In vitro, the purified cysteine mutant proteins bind to the mer operator site with near wild-type affinity but are variably deficient in binding the in vivo inducer mercury(II) ion. A subset of the isolated proteins also appears compromised in their ability to form dimers at low protein concentrations. These data, taken with the results in the preceding paper (Shewchuk et al., 1989), support a model in which DNA-bound MerR dimer binds one mercuric ion and transmits this occupancy information to a protein region involved in transcriptional activation.

Amino acid metabolism in uremia.

Abstract: The uremic syndrome is multifactorial, and affects most tissues and organs. Disturbances in protein and amino acid metabolism may play important roles, especially in chronic uremia, either directly or by production of toxic metabolites, with resultant negative nitrogen (N) balance, muscle wasting, reduced protein synthesis, and characteristically abnormal intracellular free amino acid concentrations. There are also grossly abnormal amino acid levels in the plasma of uremic patients, e.g., increases in conjugated amino acids, high levels of several nonessential and low levels of essential amino acids. The ratios of tyrosine/phenylalanine and of valine/glycine are decreased. The low tryptophan levels may contribute to encephalopathy as a result of an imbalance in neurotransmitter synthesis. Citrulline is found in excess; the explanation is unresolved. There are elevated concentrations of the sulfur-containing amino acids: cystine, taurine, cystathionine, and homocysteine. Excess of the latter is implicated in the atherogenesis of renal failure. Disturbed metabolism and interorgan exchange of amino acids in the uremic state explains some of the abnormalities in tissue and plasma concentrations of individual amino acids. Enzymatic defects are involved in the disturbed metabolism of branched chain amino acids (BCAA), with possible antagonism among them, which impairs growth and amino acid utilization. Carbohydrate intolerance, associated with insensitivity of peripheral tissues to insulin and hyperinsulinemia, elicits decreased plasma BCAA. Protein synthesis rates in normal and pathological conditions are more closely related to the intracellular amino acid pool than to plasma amino acid levels. Concentrations of individual amino acids in the plasma pool are poor indicators of their intracellular concentrations. Muscle contains the largest pool of protein and free amino acids in the body. In chronic renal failure patients, the intracellular concentrations of valine, threonine, lysine, and carnosine are low. With low protein diets and in hemodialysis, serine, tyrosine, and taurine often are also low. The low taurine may be related to fatigue and to uremic cardiomyopathies. The commonly used amino acid supplements generally fail to correct the intracellular amino acid deficits. A "New Formula" has been developed to correct these intracellular amino acid abnormalities, and to supplement a low protein diet. It provides more valine than leucine, increased tyrosine and threonine, and less histidine, leucine, isoleucine, lysine, methionine, and phenylalanine than in formulas customarily used for patients with chronic renal failure. It is uncertain whether other ap

Levels of milk urea, plasma constituents and rumen liquid ammonia in relation to the feeding of dairy cows during early lactation

Abstract: The study was undertaken to establish the relationships between milk and plasma urea levels and protein supply, using traditional and new measures of feed protein value. Samples of milk and plasma were taken before morning feeding twice weekly for the first 3 months post partum from 21 multiparous cows and 7 heifers. Samples of rumen fluid were collected every second week. The cows were distributed into 4 different feeding groups. Feeding regimens were factorial with respect to protein content of the concentrates (i.e. Low protein (Lp): 12.5% digestible crude protein (DCP) vs. High protein (Hp): 17.5% DCP) and concentrate allowances (i.e. Low energy (Le): substandard vs. High energy (He): standard). Silage was offered ad libitum. The within-animal coefficients of correlation between milk and plasma urea levels, and between milk urea levels and the levels of ammonia in the rumen fluid wer r = 0.88 (p less than 0.001) and r = 0.75 (p less than 0.001), respectively. Analysis of variance showed the following sources of urea variation to be significant: Protein balance in the rumen (PBV), intake of DCP, intake of amino acids absorbed in the intestine (AAT), intake of fattening feed units, and the individual animal factor. A similar tendency was found for the variation of ammonia in rumen fluid. The coefficients of determination (R2 model) were not increased by introducing protein balance (BADCP), the amount of PBV and AAT in the dry matter ingested, or the protein/energy ratio as alternative parameters of protein intake in the models. The levels of protein or energy intake did not significantly influence the levels of plasma albumin. The correlations between urea levels and other plasma indicators of metabolic status and liver function were generally low.

Independent effects of fiber and protein on colonic luminal ammonia concentration.

Abstract: The potential interactive effects of protein and fiber on cecal and colonic surface areas, colonic luminal ammonia concentrations, luminal pH and blood indices of nitrogen metabolism were tested using two levels of protein (8% and 24%) and two types of fiber (8% pectin or cellulose). Pectin supplementation resulted in larger cecal surface areas and longer large intestines than those of rats fed fiber-free or cellulose-supplemented diets. All high protein diets resulted in total large bowel luminal ammonia (NH3 + NH4+) concentrations that were twice as high as their low protein counterparts (P less than 0.05). The effect of fiber on ammonia concentration depended on the fiber type. In the distal colon, pectin-fed animals had three times the ammonia concentration of the fiber-free animals, and 4-5 times the ammonia concentration of the cellulose-fed animals (P less than 0.001). Blood urea nitrogen values were higher in the high protein than in the low protein groups (P less than 0.05), and highest in the high protein/pectin animals (P less than 0.01). This study clearly demonstrates that luminal ammonia concentration is dependent upon both protein level and fiber type, and that a fermentable fiber (pectin), rather than decreasing colonic ammonia concentrations, actually increases them several-fold.

Human T-lymphoblast deoxycytidine kinase: purification and properties.

Abstract: Previous observations present tremendous variations in the properties of deoxycytidine kinase. To clarify the properties and physiologic role of deoxycytidine kinase, we have undertaken its purification. Deoxycytidine kinase was purified from cultured human T-lymphoblasts (MOLT-4) to 90% purity with an estimated specific activity of 8 mumol min-1 (mg of protein)-1. The purification procedure included ammonium sulfate precipitation, Superose-12 HPLC gel filtration chromatography, DE-52 ion-exchange chromatography, AMP-Sepharose 4B affinity chromatography, and dCTP-Sepharose-4B affinity chromatography. Deoxyguanosine, deoxyadenosine, and cytidine phosphorylating activities copurified with deoxycytidine kinase to final specific activities of 7.2, 13.5, and 4 mumol min-1 (mg of protein)-1, respectively. The enzyme is very unstable at low protein concentration and is stabilized by storage at -85 degrees C with 1 mg/mL bovine serum albumin, 20% glycerol (v/v), 200 mM potassium chloride, and 25 mM dithiothreitol. The molecular weight was 60,000, and the Stokes radius was 32 A by gel filtration chromatography. The subunit molecular weight was 30,500. This enzyme had apparent Km values of 1.5, 430, 500, 450, and 40 microM for deoxycytidine, deoxyguanosine, deoxyadenosine, cytidine, and cytosine arabinoside, respectively. The pH optimum ranged from 6.5 to 9.0. Mg2+ and Mn2+ were the preferred divalent cations. ATP, GTP, dGTP, ITP, dITP, TTP, and XTP were substrates for the enzymes. Our study indicates that deoxycytidine kinase is a dimer with two subunits and has phosphorylating activity for deoxyguanosine, deoxyadenosine, cytidine, and cytosine arabinoside. This highly purified enzyme will facilitate the study of its regulation and phosphorylation of anticancer or antiviral nucleoside analogues.

Effect of Environmental Enrichment during Nutritional Rehabilitation on Body Growth, Blood Parameters and Cerebral Cortical Development of Rats

Abstract: Environmental enrichment has been reported to aid recovery from behavioral deficits associated with malnutrition in infants and young rats. This study investigated whether corresponding neuroanatomical changes could be detected. Rats were suckled either by well-fed dams or dams malnourished during lactation. At weaning, well-fed males were either housed in pairs (standard condition, SC) or 12 per large cage with toys (enriched condition, EC) and fed a 17% protein diet (SC control and EC control, respectively). Malnourished pups were fed either a 17% (rehabilitation; "rehab") or a 6% (low protein) protein diet and housed in the SC or EC environment (SC rehab, EC rehab, SC low protein, and EC low protein). After 30 d there were no differences in hematocrit, serum total protein and albumin levels between SC and EC animals. Rehab rats had significantly lower serum total protein and albumin levels than did controls. Cortical thickness and dendritic branching of occipital cortex pyramidal cells were evaluated. Early malnutrition did not permanently affect cortical thickness. EC rehab rats had thicker cortices than did SC rehab rats at almost all locations measured. SC rehab rats had fewer high order dendrites than did SC controls. The difference in dendritic branching between EC and SC rats was 44% among rehab rats, 21% among controls and 11% (not significant) among low protein-fed rats. Environmental enrichment during nutritional rehabilitation enhances dendritic branching and thickness of the occipital cortex.

Influence of copolymer composition on protein adsorption and structural rearrangements at the polymer surface

Abstract: The influence of copolymer composition on protein adsorption and subsequent structural rearrangements of the adsorbed protein has been studied by (1) investigating the ability of adsorbed proteins to be displaced by proteins in solution and (2) by determining the ability of an immobilized antibody to recognize an antigen—enzyme conjugate. Surfactant-free polystyrene copolymeric latexes were used to study the effect of specific comonomers [acrylic acid (AA), methacrylic acid (MAA), 2-hydroxyethyl acrylate (HEA), and acrylamide (A)] on protein adsorption. Although the classical surface techniques of microelectrophoresis and surfactant titration could not distinguish between the different polystyrene copolymers, the extent and nature of protein adsorption were influenced substantially by the copolymer composition. Adsorption was essentially irreversible with respect to dilution but adsorbed proteins could be displaced by proteins in solution. The order of effectiveness was fibrinogen > immunoglobulin > albumin. the ability of adsorbed proteins to be displaced from surfaces followed the order PS/PHEA > PS/PAA > PS/PMAA > PS (easiest to most difficult displacement). The retention of activity of an immobilized monoclonal antibody (Phe 1.9) at the surface followed the order PS/PHEA > PS/PAA = PS/PMAA > PS (greatest to least active). Protein adsorbed to polystyrene under low protein concentrations was less readily displaced than protein adsorbed at saturating protein concentrations. Similarly, the activity of the monoclonal antibody Phe 1.9 was dependent on the final adsorbed protein concentration at the surface of polystyrene homopolymer. In contrast, the activity of Phe 1.9 immobilized on copolymer containing HEA, AA, or MAA varied little if any with the final protein concentration at the surface. The retention of activity of covalently immobilized Phe 1.9 on poly(styrene—co-chloromethylstyrene) copolymers followed the order PS/PCS/PA > PS/PCS/PHEA(3) > PC/PCS/PHEA(1) > PS/PCS/PAA > PS/PCS/PMAA = PS/PCS (greatest to least activity). Thus, the inclusion of “modifier monomers” that are hydrophilic or are capable of hydrogen bonding with proteins appears to moderate structural rearrangements of an immobilized protein reflected by both the ease of displacement from the surface and the retention of biological activity.

Effects of inhaled acids on airway mucus and its consequences for health.

Abstract: The high molecular fractions, i.e., greater than 100,000 dalton, are found to be most responsible for the H+ ion absorption capacity of the mucus in the respiratory tract. This function serves as a protection against the penetration of the H+ ion to the surrounding tissue. Acidifying mucus with a high concentration of protein, mainly glycoproteins, results in increased viscosity, which affects various lung functions. After acid saturation of the mucus, the H+ ion will react with the epithelial tissue, which results in increased permeability and a variety of effects. Acidic mucus or mucus with a low protein concentration, as in some asthmatics, constitutes a base for risk groups regarding acidic exposures. A rough estimate indicates that persons with normal mucus buffer capacity and protein content can tolerate about 3000 micrograms SO2/m3 or 300 micrograms H2SO4/m3 per 30 min.

Familial occurrence of the antiphospholipid syndrome.

Abstract: In a family of four the whole spectrum of antiphospholipid and associated antibodies was present but without evidence of connective tissue disease. All four members had anticardiolipin antibodies; two had a confirmed lupus anticoagulant. Thrombocytopenia was severe in one and associated with a high titre of antiplatelet antibody, while another member was found to have a positive antiglobulin test. One member also had a low protein C concentration while two had decreased concentration of protein S. Factors that predispose to these antibodies may be environmental as well as genetic. In view of the well known association of spontaneous thrombotic events with some of these antibodies the prognosis for the family members must be guarded.

Adaptation to Low Protein and Energy Intakes

Abstract: This paper focuses on two principal issues. First, what are the consequences of low dietary protein and amino acid intakes? Second, what are the physiological and social limits to restricted energy intakes? The concepts of adaptation and accommodation are presented. It is suggested that the limit of adaptation to low dietary protein is achieved at the intake level considered minimally necessary to maintain health in well-nourished subjects, as judged by nitrogen balance, stable lean body mass and absence of functional impairment. For lower protein intakes survival is prolonged via an accommodation, involving loss of lean body mass and reduced rates of protein and amino acid turnover. There is only a limited metabolic capacity for adaptation to reduced energy intakes, but variations in the level and pattern of physical activity permit a maintenance of body energy balance over a broad range of energy intakes. Where reduced physical activity to balance restricted energy intakes has adverse social, cultural a...

Effects of Chronic and Acute Protein Administration on Renal Function in Patients with Chronic Renal Insufficiency

Abstract: In 6 volunteers with normal renal function, we investigated the effects of various kinds of protein (soy, lactoprotein and beef) and various amounts of an intravenously administered amino acid solution on glomerular filtration (GFR) and effective renal plasma flow (ERPF). As for the protein-induced changes in renal function, rises in GFR and ERPF were lowest with soy protein, and highest with beef (baseline GFR, 110 +/- 5; soy, 122 +/- 5; beef, 131 +/- 5 ml/min/1.73 m2; mean +/- SEM). High doses of intravenous amino acids induced a rise in GFR comparable to that after beef (132 +/- 5 ml/min/1.73 m2). In a combined test a liquid mixed meal together with intravenously administered amino acids induced a comparable increase of the GFR (baseline 114 +/- 5 versus 129 +/- 5 ml/min/1.73 m2). When investigating 9 patients with chronic renal insufficiency after 4 weeks of low protein intake (LP) and after 4 weeks of high protein intake (HP), GFR and ERPF rose significantly under baseline conditions (GFR-LP41 +/- 9 versus GFR-HP 45 +/- 9 ml/min/1.73 m2, p less than 0.02; ERPF-LP 169 +/- 39 versus ERPF-HP 180 +/- 40 ml/min/1.73 m2, p less than 0.02; paired Wilcoxon). At the end of both dietary periods a comparable rise in renal function could be induced through acute stimulation (GFR-LP 20 +/- 5, GFR-HP 16 +/- 4; ERPF-LP 23 +/- 7, ERPF-HP 22 +/- 3%).(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary Protein Deficiency and Mycobacterium Bovis BCG Affect Interleukin-2 Activity in Experimental Pulmonary Tuberculosis

Abstract: Inbred strain 2 guinea pigs were vaccinated with Mycobacterium bovis BCG or were left unvaccinated. They were maintained for 6 weeks on defined, isocaloric diets containing either 30% (control animals) or 10% (animals receiving low protein) ovalbumin as the sole protein source. Animals were challenged by the respiratory route with a low dose of virulent M. tuberculosis H37Rv and killed 4 weeks later. Protein-malnourished animals were not protected by previous vaccination with BCG. Lymphocytes isolated from various tissues were tested in vitro for proliferative responses to mitogen (concanavalin A) and antigen (purified protein derivative [PPD]), production of interleukin-2 (IL-2), and response to exogenous recombinant IL-2 (rIL-2). Protein-malnourished guinea pigs responded only weakly to PPD skin tests, and their blood and lymph node lymphocytes exhibited impaired proliferation when cultured with PPD in vitro. IL-2 levels were consistently low in cultures of stimulated blood and spleen lymphocytes from protein-deprived animals. BCG vaccination of nutritionally normal guinea pigs, on the other hand, induced significantly more IL-2 production by PPD- and concanavalin A-stimulated lymphocytes. The addition of exogenous mouse rIL-2 (40 and 80 U/ml) in vitro to PPD-stimulated blood and lymph node cells from nonvaccinated, protein-deprived guinea pigs resulted in no improvement of the proliferative response. Previous vaccination of malnourished guinea pigs did not consistently enhance the response of PPD-stimulated lymphocytes to added rIL-2. Dietary protein deficiency and BCG vaccination appear to modulate antigen-driven cellular immunity in animals with tuberculosis by altering the production of, and the response to, IL-2 by PPD-stimulated lymphocytes.

Nuclear proteins binding to a cauliflower mosaic virus 35S truncated promoter.

Abstract: Proteins present in tobacco nuclear extracts bind to a truncated cauliflower mosaic virus (CaMV) 35S promoter fragment (from −90 to +2 relative to the transcription start site) in a sequence specific manner. Gel mobility shift assays show the presence of two protein-DNA complexes that are not competed by a −47/+2 promoter fragment. DNAse I protection and DNA methylation interference reveal two protected sites in the slower migrating complex; both include the pentamer TGACG, separated by a stretch of eight nucleotides where G methylation does not prevent the binding of the proteins. The faster complex is the prevalent form at low protein concentrations. As the protein concentration increases a non-linear rise in the amount of the slower migrating complex relative to the faster one is seen suggesting that cooperative effects are involved in the binding to the second site.

The influence of rumen volatile fatty acids on protein metabolism in growing lambs.

Abstract: The effect of acetic or propionic acid rumen fermentation patterns on whole-body protein turnover, tissue protein synthetic rates and body composition was investigated in growing lambs. Protein turnover was assessed using a continuous intravenous infusion of [2,3-3H]tyrosine and tissue protein fractional synthetic rates (FSR) from the specific activities of plasma free, intracellular free and tissue bound tyrosine. Only the FSR of muscle tissue approached significance. The high FSR in the propionic group was attributed to the high plasma insulin concentration. Values for whole-body protein synthesis, corrected for tyrosine oxidation, were similar to those obtained by summating protein synthesis in individual tissues, confirming that tyrosine oxidation should be measured accurately if reliable whole-body protein synthesis values are required. Tyrosine oxidation and flux were high in the acetic acid group, suggesting that amino acids are used for gluconeogenesis. The high protein turnover rate probably ensures an adequate supply of gluconeogenic amino acids and that the penalty of mobilizing body proteins for gluconeogenic amino acids is minimal. In the propionic acid group, high plasma glucose and insulin concentrations were associated with a low protein turnover rate, high ratio of deposited: synthesized protein and a high body fat content. It is concluded that changing the proportion of ruminal volatile fatty acids influences protein turnover, protein synthesis and the efficiency of protein retention. Such factors probably contribute, indirectly, to the observed differences in body composition.

Feed and water intake, digestibility and nitrogen utilization by camels compared to sheep and goats fed low protein desert by-products

Abstract: After having gathered data from bibliography about intake, digestibility and nitrogen retention in dromedaries, a study was carried out on 2 female dromedaries, 4 rams and 4 bucks (desert breed). This work has as objective to show the effects of digestibility and nitrogen retention on water intake in three rations: hay, 75 per cent date pits and 25 per cent hay, 75 per cent olive cake and 25 per cent hay. The results show that dromedaries consume less water than small ruminants because of their thermo-regulation if there is no difference concerning dry matter intake - when the three species eat only during the day. Sheep eat less than goats and dromedaries when the diets include date pits or olive cake. Dromedaries digest wall carbohydrates better than small ruminants but nitrogen matter worse than them. Still dromedaries retain higher quantities of nitrogen than small ruminants, except perhaps with the diet containing date wastes.