Plasma amino acid patterns during supplemental intravenous nutrition of low-birth-weight infants

In 42 low-birth-weight infants (smaller than 1,200 gm), we have compared the effects of intravenous nutrition supplement versus conventional feedings on growth, morbidity, mortality, and plasma amino acid patterns. Despite similar total caloric intake in INS and control groups, weight gain was greater in the INS infants. The overall mortality rate did not differ in the two groups. Nonsurviving infants receiving INS lived longer (mean equal to 30 days) than nonsurviving CON infants (mean equal to 5 days). Complications were equally frequent in both groups except that hyperglycemia occurred more often in infants receiving INS. The plasma aminogram of the LBW infant is described and compared to those of the full-term infant and adult. Hypoaminoacidemia was present at birth in the LBW infants, concentrations of glutamine, alamine, glycine, histidine, and ornithine being significantly (P smaller than 0.05) below FT values. During INS, elevations of threonine, serine, and methionine above FT values occurred. Glutamine remained subnormal despite INS. Recommendations for an INS solution more suitable for use in LBW infants are presented.     

Keto acids and free amino acids during leaf growth in Bauhinia purpurea L

The biosynthesis of keto acids and free amino acids was studied during the growth of Bauhinia purpurea leaves. Alpha-KGA, OAA, pyruvic acid and PEP are the important keto acids observed at various stages. The first 2 metabolites show a progressive increase and PEP leads to OAA pathway is very active during the process of growth.     

Representation of amino acid sequences as two-dimensional point patterns

An algorithm for the representation of amino acid sequences as two-dimensional point patterns (2-D plot) is described. The algorithm is based on chaos game representation (CGR) for DNA sequences and was extended for amino acid sequences. The 2-D plot depicts the sequentiality of amino acids and the amino acid composition of a protein. Changes in a protein sequence as insertion, deletion and repeats of amino acids are characterized by specific geometrical properties and changes in the 2-D plots. The 2-D plot may be considered as a two-dimensional "fingerprint" of a protein. The properties of the algorithm are explained by user-defined amino acid sequences. As an example the 2-D plots of two selected heart proteins are generated. The sequences of these proteins are obtained from the protein sequence database SWISS-PROT.     

Strain differences in patterns of drug-intake during prolonged access to cocaine self-administration.

The current study examined possible interactions between genetic factors and prolonged drug access by testing the Fischer (F344), Lewis (LEW), and Wistar rat strains in a prolonged access cocaine self-administration (SA) procedure. Before prolonged access, the strains did not differ in breakpoints for food or cocaine with progressive ratio (PR) testing. The LEW and Wistar rats acquired cocaine SA faster than the F344s. With prolonged access to cocaine SA, the LEW and Wistar rats showed comparable within-session patterns that were higher at the outset of each session and decreased to a stable baseline. Alternatively, the F344 rats began sessions with lower intake and increased their rate of intake during the session. The F344 and Wistar rats took more drug per session than the LEW rats but did not differ from each other. Following prolonged access, the strains did not differ in breakpoints for food, but the Wistar rats had higher breakpoints for cocaine than the F344 rats. Possible underpinnings for the observed strain differences are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contrasting plasma free amino acid patterns in elite athletes: association with fatigue and infection

AIM: There is little information on the plasma free amino acid patterns of elite athletes against which fatigue and nutrition can be considered. Therefore the aim was to include analysis of this pattern in the medical screening of elite athletes during both especially intense and light training periods. METHODS: Plasma amino acid analysis was undertaken in three situations. (1) A medical screening service was offered to elite athletes during an intense training period before the 1992 Olympics. Screening included a blood haematological/biochemical profile and a microbial screen in athletes who presented with infection. The athletes were divided into three groups who differed in training fatigue and were considered separately. Group A (21 track and field athletes) had no lasting fatigue; group B (12 judo competitors) reported heavy fatigue at night but recovered overnight to continue training; group C (18 track and field athletes, one rower) had chronic fatigue and had been unable to train normally for at least several weeks. (2) Athletes from each group were further screened during a post-Olympic light training period. (3) Athletes who still had low amino acid levels during the light training period were reanalysed after three weeks of additional protein intake. RESULTS: (1) The pre-Olympics amino acid patterns were as follows. Group A had a normal amino acid pattern (glutamine 554 (25.2) micromol/l, histidine 79 (6.1) micromol/l, total amino acids 2839 (92.1) micromol/l); all results are means (SEM). By comparison, both groups B and C had decreased plasma glutamine (average 33%; p<0.001) with, especially in group B, decreased histidine, glucogenic, ketogenic, and branched chain amino acids (p<0.05 to p<0.001). None in group A, one in group B, but ten athletes in group C presented with infection: all 11 athletes had plasma glutamine levels of less than 450 micromol/l. No intergroup differences in haematological or other blood biochemical parameters, apart from a lower plasma creatine kinase activity in group C than in group B (p<0.05) and a low neutrophil to lymphocyte ratio in the athletes with viral infections (1.2 (0.17)), were found. (2) During post-Olympic light training, group A showed no significant amino acid changes. In contrast, group B recovered normal amino acid levels (glutamine 528 (41.4) micromol/l, histidine 76 (5.3) micromol/l, and total amino acids 2772 (165) micromol/l) (p<0.05 to p<0.001) to give a pattern comparable with that of group A, whereas, in group C, valine and threonine had increased (p<0.05), but glutamine (441 (24.5) micromol/l) and histidine (58 (5.3) micromol/l) remained low. Thus none in group A, two in group B, but ten (53%) in group C still had plasma glutamine levels below 450 micromol/l, including eight of the 11 athletes who had presented with infection. (3) With the additional protein intake, virtually all persisting low glutamine levels increased to above 500 micromol/l. Plasma glutamine rose to 592 (35.1) micromol/l and histidine to 86 (6.0) micromol/l. Total amino acids increased to 2761 (128) micromol/l (p<0.05 to p<0.001) and the amino acid pattern normalised. Six of the ten athletes on this protein intake returned to increased training within the three weeks. CONCLUSION: Analysis of these results provided contrasting plasma amino acid patterns: (a) a normal pattern in those without lasting fatigue; (b) marked but temporary changes in those with acute fatigue; (c) a persistent decrease in plasma amino acids, mainly glutamine, in those with chronic fatigue and infection, for which an inadequate protein intake appeared to be a factor.     

Developmental patterns of acid hydrolases during differentiation of fetal mouse skin

A dye reduction method was developed for estimating total aerobic and/or psychrotrophic bacterial counts in ground beef. The method is based on color changes in indicator disks placed on the meat surface.     

Evidence for a catabolic role of glucagon during an amino acid load

Despite the strong association between protein catabolic conditions and hyperglucagonemia, and enhanced glucagon secretion by amino acids (AA), glucagon's effects on protein metabolism remain less clear than on glucose metabolism. To clearly define glucagon's catabolic effect on protein metabolism during AA load, we studied the effects of glucagon on circulating AA and protein dynamics in six healthy subjects. Five protocols were performed in each subject using somatostatin to inhibit the secretion of insulin, glucagon, and growth hormone (GH) and selectively replacing these hormones in different protocols. Total AA concentration was the highest when glucagon, insulin, and GH were low. Selective increase of glucagon levels prevented this increment in AA. Addition of high levels of insulin and GH to high glucagon had no effect on total AA levels, although branched chain AA levels declined. Glucagon mostly decreased glucogenic AA and enhanced glucose production. Endogenous leucine flux, reflecting proteolysis, decreased while leucine oxidation increased in protocols where AA were infused and these changes were unaffected by the hormones. Nonoxidative leucine flux reflecting protein synthesis was stimulated by AA, but high glucagon attenuated this effect. Addition of GH and insulin partially reversed the inhibitory effect of glucagon on protein synthesis. We conclude that glucagon is the pivotal hormone in amino acid disposal during an AA load and, by reducing the availability of AA, glucagon inhibits protein synthesis stimulated by AA. These data provide further support for a catabolic role of glucagon at physiological concentrations.     

Role of specific amino acid residues in T4 endonuclease V that alter nontarget DNA binding

Endonuclease V is a pyrimidine dimer-specific DNA glycosylase-apurinic (AP)1 lyase which, in vivo or at low salt concentrations in vitro, binds nontarget DNA through electrostatic interactions and remains associated with that DNA until all dimers have been recognized and incised. On the basis of the analyses of previous mutants that effect this processive nicking activity, and the recently published cocrystal structure of a catalytically deficient endonuclease V with pyrimidine dimer-containing DNA [Vassylyev, D. G., et al. (1995) Cell 83, 773-782], four site-directed mutations were created, the mutant enzymes expressed in repair-deficient Escherichia coli, and the enzymes purified to homogeneity. Steady-state kinetic analyses revealed that one of the mutants, Q15R, maintained an efficiency (k(cat)/Km) near that of the wild-type enzyme, while R117N and K86N had a 5-10-fold reduction in efficiency and K121N was reduced almost 100-fold. In addition, K121N and K86N exhibited a 3-5-fold increase in Km, respectively. All the mutants experienced mild to severe reduction in catalytic activity (k(cat)), with K121N being the most severely affected (35-fold reduction). Two of the mutants, K86N and K121N, showed dramatic effects in their ability to scan nontarget DNA and processively incise at pyrimidine dimers in UV-irradiated DNA. These enzymes (K86N and K121N) appeared to utilize a distributive, three-dimensional search mechanism even at low salt concentrations. Q15R and R117N displayed somewhat diminished processive nicking activities relative to that of the wild-type enzyme. These results, combined with previous analyses of other mutant enzymes and the cocrystal structure, provide a detailed architecture of endonuclease V-nontarget DNA interactions.     

Barley beta-glucosidase: expression during seed germination and maturation and partial amino acid sequences

Confusion regarding proper use of the terms rate and risk persists in the literature. This has implications for the proper modeling of prognosis and transition between health states in decision analysis and related techniques. The issue is complicated by the plethora of terms related to rate and risk. Although the suggestion to use the terms force and probability as substitutes for rate and risk has some appeal, the change in terminology by itself is unlikely to solve all the confusion or misuse of terms. This paper clarifies the proper definitions and estimations of rates and risks and suggests critical factors for the decision analyst to remember when using, modeling, or interpreting transition rates and risks.     

Thyrotropin receptor cleavage at site 1 does not involve a specific amino acid motif but instead depends on the presence of the unique, 50 amino acid insertion

Thyrotropin (TSH) receptor (TSHR) A and B subunits are formed by intramolecular cleavage of the single chain receptor at two separate sites. The region involved in cleavage at Site 2 has been identified, but previous mutagenesis studies failed to identify Site 1. We now report fortuitous observations on the effect of trypsin on the TSHR that localizes a small region harboring Site 1. Thus, as detected by immunoblotting and by 125I-TSH cross-linking to TSHR expressed on the surface of intact CHO cells, trypsin clipped a small polypeptide fragment bearing a glycan moiety from the C terminus of the A subunit. Based on the TSHR primary structure, this small fragment (1-2 kDa) contains Asn-302. This information, together with estimation of the size of the deglycosylated A subunit relative to a series of C-terminal truncated TSHR ectodomain variants, places cleavage Site 1 in the vicinity of, or closely upstream to, residue 317. Remarkably, mutagenesis of every amino acid residue between residues 298-316 (present study) and 317-362 (previous data) did not prevent cleavage at Site 1. However, cleavage at this site was abrogated by deletion of a 50-amino acid segment (residues 317-366) unique to the TSHR in the glycoprotein hormone receptor family. In summary, these data provide novel insight into TSHR intramolecular cleavage. Cleavage at Site 1 does not depend on a specific amino acid motif and differs from cleavage at Site 2 by involvement of a mechanism requiring the presence of the enigmatic TSHR 50-amino acid "insertion."     

Preexercise meal composition alters plasma large neutral amino acid responses during exercise and recovery

This study was designed to determine metabolic and physical performance responses to ingestion of pre-exercise meals with different macronutrient and fiber profiles. Twelve physically active subjects (6 males and 6 females) were used to investigate the metabolic and physical performance consequences of consuming pre-exercise meals consisting of oat, corn, or wheat cereals. A fasting trial served as the control, and all subjects received each treatment in a Latin-square design. Blood samples were drawn before and 85 min after meal ingestion, during 90 min of cycling exercise (60% VO2peak), after a 6.4 km performance ride, and during 60 min of recovery. Expired air samples were collected to determine nutrient utilization. Resting carbohydrate oxidation rates and plasma insulin concentrations after oat ingestion were less than after wheat, and corn and wheat ingestion, respectively (P < 0.05). During exercise, the change in plasma glucose from pre-exercise was greater after consuming wheat and corn compared with oat (P < 0.05), and it was inversely related to pre-exercise plasma insulin concentration (r = -0.55, P = 0.0001). Plasma free fatty acid concentrations were inversely related to plasma lactate concentrations (r = -0.58, P = 0.0001). Free fatty acid concentrations and fat oxidation were greater in fasting trials than all others, but performance ride times did not differ among treatments. Plasma branched-chain amino acid concentrations resembled their respective meal profiles throughout exercise, the performance ride, and recovery. These results indicate that pre-exercise meal composition can influence glucose homeostasis during early exercise and plasma branched-chain amino acid concentrations over a substantial range of metabolic demands.     

Longitudinal changes of brain amino acid content occurring before, during and after epileptic activity

In cats affected with cortical epileptogenic foci induced by penicillin application to and cobalt implantation into the pericruciate area, the brain amino acids contents were determined in the focus as well as in extrafocal areas. In different groups of animals, brain removal for biochemical determinations was performed at different times before, during and after epilepsy and the values compared to controls. The only amino acid to show a significant change before appearance of spikes in both types of epilepsy was taurine, which decreased. Cobalt epilepsy was accompanied by changes in a larger number of amino acids than penicillin epilepsy: in the former the brain content of taurine, GABA, aspartate, glutamate, serine, threonine, glycine and alanine was altered. The changes were proportional to the severity of epilepsy and more prominent in the focus area. After disappearance of spikes the levels of most amino acids returned to normal except for some amino acids, previously unaffected by penicillin epilepsy, which were decreased. It is proposed that the decrease in brain taurine, occurring before the appearance of penicillin and cobalt epilepsy, could increase the excitability of a certain neuronal population and thus, by potentiating the effects on neurons of penicillin and cobalt, contribute to the initiation of epilepsy.     

Excitatory amino acid receptors and puberty

Glutamate is an important excitatory signal in the hypothalamus for the steroid-mediated preovulatory gonadotropin surge. Steroids may exert this action by regulating glutamate receptor levels or glutamate release, or both. Work in our laboratory found no changes in NMDA and kainate receptor binding in the hypothalamus of castrated or castrated plus steroid-replaced male and female rats. Likewise, we found that NMDA and kainate binding did not change over the onset of puberty in the female rat. A competitive quantitative RT-PCR assay using exogenous internal standards was used to measure NMDAR1, GluR1, and beta-actin mRNAs levels. NMDAR1 and GluR1 expression was examined in the preoptic hypothalamic area and in the medial basal hypothalamus at Postnatal Days 10, 15, 20, 25, 30, 32, 34, 36, 40, and 63. A transient increase in GluR1 mRNA levels in the preoptic hypothalamic area was observed on Day 20, with all other time points showing comparable levels. NMDAR1 levels in the POA and medial basal hypothalamus did not change significantly at any of the time points; in contrast, however, AMPA receptor binding levels were increased in the hypothalamus at the time of puberty in the female rat. Thus, in addition to the previously reported elevation of glutamate release rates in the hypothalamus at the time of puberty, AMPA receptors may also be elevated and play a role in mediating glutamate regulatory effects on the timing of puberty in the female rat.     

Hydrolysis and amino acid composition of proteins

Amino acid composition analysis is a classical protein analysis method, which finds a wide application in medical and food science research and is indispensable for protein quantification. It is a complex technique, comprising two steps, hydrolysis of the substrate and chromatographic separation and detection of the residues. A properly performed hydrolysis is a prerequisite of a successful analysis. The most significant developments of the technology in the last decade consist in the (i) reduction of the hydrolysis time by the use of microwave radiation energy; (ii) improvement in the sensitivity of the residue detection, the quantification of the sensitive residues and separation of the enantiomeric forms of the amino acids; (iii) application of amino acid analysis in the large-scale protein identification by database search; and (iv) gradual replacement of the original ion exchange residue separation by reversed-phase high-performance liquid chromatography. Amino acid analysis is currently facing an enormous competition in the determination of the identity of proteins and amino acid homologs by the essentially faster mass spectrometry techniques. The amino acid analysis technology needs further simplification and automation of the hydrolysis, chromatography and detection steps to withstand the pressure exerted by the other technologies.     

The effect of amino acids and amino acid derivatives on cell proliferation

The effect of certain amino acids and amino acid derivatives on cell proliferation have been studied in the author's Institute for more than 25 years. The optically active forms of arginine, lysine, aspartic acid and glutamic acid influence the growth of transplantable rat tumors. L-arginine, D-lysine, L-aspartic acid and D-glutamic acid promoted; D-aspartic acid, L-glutamic acid, D-arginine and L-lysine inhibited tumour growth. E-amino trimethyl-lysine (TML) stimulated cell proliferation in various cell systems (bone marrow, small intestine, cultured lymphocytes). When administered simultaneously with high doses of Cyclophosphamide, Vincristin or Doxorubicin to tumour-bearing mice, TML decreased the toxicity of the antitumour drugs, resulting in a higher rate of survivors. L-leucine methyl ester caused cell death of mouse peritoneal macrophages by inducing disruption of macrophages.     

Defective nonoxidative leucine degradation and endogenous leucine flux in cirrhosis during an amino acid infusion

The metabolic fate of leucine's first and second carbon may be different depending on the tissue in which leucine is metabolized, as well as the prevailing hormonal milieu of that tissue. However, previous studies of leucine kinetics in humans have used only leucine labeled (as tracer) at the first carbon position. Because cirrhosis is associated with factors (such as insulin resistance and altered fuel substrate utilization) that may influence how leucine is degraded, the kinetics of leucine's first and second carbon using a simultaneous infusion of [1-14C] leucine and [2-13C] leucine were studied in the postabsorptive state and during an amino acid infusion in 6 stable cirrhotic patients and 6 matched controls. The data were normalized for different body compartments that were quantified from the dilution of H2 [180] and bromide. The body cell mass, but not body weight or fat-free body mass, was decreased in cirrhosis (P < .001). In response to the amino acid infusion, total leucine appearance from proteolysis and leucine's incorporation into protein increased significantly in both groups, but were higher in cirrhotic patients. Endogenous protein breakdown decreased in normals but remained unchanged in cirrhosis. These alterations in leucine metabolism became more prominent when data were expressed based on the body cell mass rather than on body weight. The oxidation of leucine's first carbon (C1) was decreased in cirrhosis, but the oxidation of leucine's second carbon (C2) did not differ between groups during both the postabsorptive period and the amino acid infusion, while nonoxidative leucine degradation [the difference between the oxidation of leucine's (C1) and (C2)] was also decreased in cirrhosis. In addition, there was a positive correlation between nonoxidative leucine degradation (which represents leucine incorporation into fat), and the respiratory quotient obtained from indirect calorimetry (r = .87; P < .001). These data suggest that the extent of leucine carbon oxidation is dependent on whether fat or carbohydrate is the prevailing fuel substrate. In addition, cirrhotic patients have decreased nonoxidative leucine degradation and are unable to suppress endogenous protein breakdown normally in response to amino acid administration. These abnormalities may contribute to the diminished fat stores and body cell mass commonly observed in cirrhosis.     

Antigenically profound amino acid substitutions occur during large population passages of foot-and-mouth disease virus

Protein kinase C (PKC) is an ubiquitous regulatory enzyme with dense myocardial distribution and activity; however, its physiologic relevance to myocardial function remains poorly understood. Although endogenous Ca2+ is a potent stimulus of PKC isoforms alpha and beta (cPKCs) it remains unknown whether exogenous Ca2+ activates these PKC isoforms, and if so, whether PKC plays any role in Ca2+-induced myocardial inotropy. To study this, ventricular sections from isolated rat hearts, with and without Ca2+-induced inotropy (CaCl2, 0.5 mM coronary concentration x 2 min), were probed for cPKC isoform translocation using immunofluorescence in order to determine if exogenous Ca2+ indeed activates cPKCs. We further examined the effects of exogenous Ca2+, with and without concurrent PKC inhibition (chelerythrine, 20 microM coronary concentration x 2 min), on fundamental physiologic parameters of myocardial developed pressure (DP), dP/dt, and coronary flow (CF) in the isolated rat heart to determine if Ca2+-induced inotropy involves PKC. Results indicated that exogenous Ca2+ results in translocation of PKC a from the cytoplasm to the sarcolemma and intercalated discs, as well as the translocation of PKC beta from the perinuclear to the intranuclear compartment. This dose of exogenous Ca2+ resulted in myocardial inotropy as determined by DP, dP/dt, and CF. Furthermore, myocardial inotropy was attenuated with concurrent inhibition of PKC activity. These findings link the physiologic effects of exogenous Ca2+ to PKC, providing a better understanding of the physiologic mechanism of Ca2+-induced inotropy.     

Developmental control of H+/amino acid permease gene expression during seed development of Arabidopsis

Long distance transport of amino acids is mediated by several families of differentially expressed amino acid transporters. The two genes AAP1 and AAP2 encode broad specificity H(+)-amino acid co-transporters and are expressed to high levels in siliques of Arabidopsis, indicating a potential role in supplying the seeds with organic nitrogen. The expression of both genes is developmentally controlled and is strongly induced in siliques at heart stage of embryogenesis, shortly before induction of storage protein genes. Histochemical analysis of transgenic plants expressing promoter-GUS fusions shows that the genes have nonoverlapping expression patterns in siliques. AAP1 is expressed in the endosperm and the cotyledons whereas AAP2 is expressed in the vascular strands of siliques and in funiculi. The endosperm expression of AAP1 during early stages of seed development indicates that the endosperm serves as a transient storage tissue for organic nitrogen. Amino acids are transported in both xylem and phloem but during seed filling are imported only via the phloem. AAP2, which is expressed in the phloem of stems and in the veins supplying seeds, may function in uptake of amino acids assimilated in the green silique tissue, in the retrieval of amino acids leaking passively out of the phloem and in xylem-to-phloem transfer along the path. The promoters provide excellent tools to study developmental, hormonal and metabolic control of nitrogen nutrition during development and may help to manipulate the timing and composition of amino acid import into seeds.