Effect of infusing branched-chain amino acid during incremental exercise with reduced muscle glycogen content

The aim of this study was to investigate whether, when muscle glycogen is reduced, a pre-exercise infusion of branched-chain amino acids (BCAA) modifies exercise performance or the metabolic and respiratory responses to incremental exercise. Six moderately trained volunteers took part in the following protocol on two occasions. On day 1, at 9 a.m. in the postabsorptive state, they performed a graded incremental exercise (increases of 35 W every 4 min) to exhaustion (Ex-1). A meal of 1,000 kcal (4,200 kJ; 60% protein, 40% fat) was consumed at 12 p.m. No food was then allowed until the end of the experiment (20–21 h later). A 90-min period of exercise at alternating high and moderate intensities, designed to deplete muscle glycogen, was performed between 6 p.m. and 7.30 p.m. The morning after (day 2), the subjects randomly received either a mixed solution of BCAA (260 mg × kg^–1 × h^–1 for 70 min), or saline. They then repeated the graded incremental exercise to exhaustion (Ex-2). Metabolic and respiratory measurements suggested a muscle glycogen-depleted state had been achieved. No significant differences were observed in total work performed, maximal oxygen uptake or plasma ammonia, alanine, and blood pyruvate concentrations in the two treatments. After BCAA infusion, higher blood lactate concentrations were observed at maximal power output in comparison with those during saline [BCAA 4.97 (SEM 0.41) mmol × l^–1, Saline 3.88 (SEM 0.47) mmol × l^–1,P < 0.05]. In summary, in conditions of reduced muscle glycogen content, after a short period of fasting, BCAA infusion had no significant effect on the total work that could be performed during a graded incremental exercise.     

Outgrowth and sporulation studies on Clostridium botulinum type E: influence of isoleucine.

A defined medium (CDM) is described which supported growth and sporulation of type E strains of Clostridium botulinum, but not sporulation of other serotypes of C. botulinum or C. sporogenes. As compared to growth in complex medium, spore outgrowth was delayed and both the growth rate and the cell yield was reduced. However, efficiency of sporulation of the type E MSpt strain in a chemically defined medium (CDM) was the same as that in complex medium and, in fact, sporulation was nearly synchronous and completed within 3 h of the first appearance of phase-bright endospores, compared with completion in 9 h in TPGY. Growth studies with CDM, from which single amino acids were omitted, showed that isoleucine was essential for outgrowth of heat-activated spores of the MSp+ strain, whereas valine was required for that of the Ts-25 mutant. Radioactive isoleucine was incorporated by germinating MSp+ spores at an earlier stage and at a more rapid rate than labelled methionine or mixed amino acids. Uptake studies showed that isoleucine accumulated in a prominent acid-soluble pool during outgrowth, a period when its incorporation into protein was not evident. The results suggest that the isoleucine may be required for a purpose other than protein synthesis during outgrowth.     

Oxidative DNA damage in circulating leukocytes occurs as an early event in chronic HCV infection

Chronic hepatitis C virus (HCV) infection is associated with an increased production of reactive oxygen species within the liver that are responsible for the oxidation of intracellular macromolecules. To ascertain whether the increased risk of hepatocellular carcinoma in individuals with chronic HCV infection is related to an accumulation of oxidative DNA damage, the 8-hydroxydeoxyguanosine (8-OHdG) content in the DNA of liver tissue and leukocytes of 87 individuals with HCV- or HBV-related liver disease and of 10 healthy controls was measured. Serum levels of thiobarbituric acid reactive substances (TBARS) were also assessed as an index of lipid peroxidation. RESULTS: The 8-OHdG content in the circulating leukocytes correlated with that of liver tissue (r = 0.618, p < .0004). HCV patients had the highest median 8-OHdG levels (p < .0004). 8-OHdG leukocyte levels in HCV patients were higher than in HBV patients (p < .04) and they significantly correlated with the clinical diagnosis (p < .025), the serum ferritin levels (p < .05), and the amount of liver steatosis (p < .001). No correlation was found with age, gender, history of drinking or smoking, ALT or GGT levels, ESR, alpha-1, or gamma-globulin level and Ishak score. TBARS levels were significantly higher in cirrhotics than in noncirrhotics (p < .01). CONCLUSIONS: The 8-OHdG level in circulating leukocytes is a reliable marker of oxidative stress occurring in the liver of individuals with chronic HCV infection. DNA oxidative damage appears to be an early and unique event in the natural history of HCV-related hepatitis. This injury increases the risk of genomic damage and may be one of the important factors involved in the carcinogenic process in cases of HCV-related chronic liver disease.     

[3H]Ketanserin Binding in Human Brain Postmortem

This study aimed at comparing the binding characteristics of [³H]ketanserin, a high-affinity serotonin 2A (5-HT_2A) receptor antagonist, in the prefrontal cortex, hippocampus and striatum of human brain post-mortem. The results indicated the presence of a single population of binding sites in all the regions investigated, with no statistical difference in maximum binding capacity (B_max) or dissociation constant (K_d) values. The pharmacological profile of [³H]ketanserin binding was consistent with the labeling of the 5-HT_2A receptor, since it revealed a competing drug potency ranking of ketanserin = spiperone > clozapine = haloperidol > methysergide > mesulergine > 5-HT. In conclusion, the 5-HT_2A receptor, as labeled by [³H]ketanserin, would seem to consist of a homogenous population of binding sites and to be equally distributed in human prefronto-cortical, limbic and extrapyramidal structures.     

Immunohistochemical Markers of Neural Progenitor Cells in the Early Embryonic Human Cerebral Cortex

The development of the human central nervous system represents a delicate moment of embryogenesis. The purpose of this study was to analyze the expression of multiple immunohistochemical markers in the stem/progenitor cells in the human cerebral cortex during the early phases of development. To this end, samples from cerebral cortex were obtained from 4 human embryos of 11 weeks of gestation. Each sample was formalin-fixed, paraffin embedded and immunostained with several markers including GFAP, WT1, Nestin, Vimentin, CD117, S100B, Sox2, PAX2, PAX5, Tβ4, Neurofilament, CD44, CD133, Synaptophysin and Cyclin D1. Our study shows the ability of the different immunohistochemical markers to evidence different zones of the developing human cerebral cortex, allowing the identification of the multiple stages of differentiation of neuronal and glial precursors. Three important markers of radial glial cells are evidenced in this early gestational age: Vimentin, Nestin and WT1. Sox2 was expressed by the stem/progenitor cells of the ventricular zone, whereas the postmitotic neurons of the cortical plate were immunostained by PAX2 and NSE. Future studies are needed to test other important stem/progenitor cells markers and to better analyze differences in the immunohistochemical expression of these markers during gestation.Key words: Cerebral cortex, human embryo, human development, immunohistochemistry, fetal stem cells     

Renal handling of amylase and immunoreactive trypsin in pancreatic cancer and chronic pancreatitis.

In order to evaluate the renal metabolism of amylase and immunoreactive trypsin (IRT) in chronic pancreatic disease, we assayed amylase, IRT and creatinine in serum and urine and gamma-glutamyl transferase (GGT) in dialyzed urine as well as alpha-glucosidase (AGL) and ribonuclease (RNase) in 24 control subjects, 34 patients with pancreatic cancer, 52 with chronic pancreatitis and 32 with extra-pancreatic diseases. Urinary amylase and IRT outputs were found to be more elevated in chronic pancreatitis than in control subjects. The levels of serum amylase, its renal inputs and outputs were correlated with the corresponding IRT values. Multiple regression analyses (dependent on amylase or IRT urinary outputs, circulating levels of the two enzymes, creatinine clearance and the excretion of GGT, AGL and RNase predictor variables) showed significant correlations. The standardized partial regression coefficients found to be significant were: GGT, RNase and serum amylase for amylase, and GGT and RNase for IRT. No difference was found between amylase and IRT outputs in patients with chronic pancreatitis, taking the presence or the absence of alcohol abuse, exocrine insufficiency and pancreatic pseudocysts into consideration. Urinary GGT excretion correlated with serum amylase and IRT levels.(ABSTRACT TRUNCATED AT 250 WORDS)     

Identification of 6-O-alpha-D-mannopyranosyl myo-inositol from Saccharomyces cerevisiae

A mannosyl inositol isolated from Baker's yeast was shown to be α-linked from the 1 position of mannose to the 6 position of myo-inositol by comparison of the products of permethylation, hydrolysis, and reduction of the disaccharide. The structure was established using chemical and enzymatic methods, gas chromatography, and combined gas chromatographymass spectrometry.     

Serum elastase 1 and immunoreactive trypsin in chronic pancreatic disease: is there any relationship with trypsin inhibitors?

In order to investigate modifications of serum levels of elastase 1, immunoreactive trypsin, alpha 1-antitrypsin and alpha 2-macroglobulin in chronic pancreatic disease, and to speculate on the possible relationships among these parameters, the enzymes and inhibitors were assayed in the sera of 33 control subjects, 34 pancreatic cancer, 28 chronic pancreatitis and 36 extra-pancreatic diseases. An increase of elastase 1, alpha 1-antitrypsin and alpha 2-macroglobulin was detected in pancreatic cancer, chronic pancreatitis and extra-pancreatic diseases; no changes were found for serum immunoreactive trypsin. Multiple regression analyses showed that only 7% of elastase 1 was explained by inhibitors with alpha 1-antitrypsin playing a major role. Inhibitors did not influence immunoreactive trypsin. Our data indicate that the variations of the serum levels of proteases and antiproteases in chronic pancreatic disease are probably independent of each other.     

Zinc,iron, and peroxidation in liver tissue

In an attempt to elucidate further the mechanisms involved in alcohol-mediated liver damage and the correlation between alcohol and viruses in chronic liver lesions, we determined the levels of liver glutathione (GSH), thiobarbituric acid reactive substances (TBARS), iron (Fe), and zinc (Zn) in 31 patients with chronic viral hepatitis (CAH), 6 with alcohol-related chronic hepatitis (CALD), 6 with alcoholic cirrhosis (AC), 8 with primary biliary cirrhosis (PBC), and 10 healthy controls (C). Liver GSH was significantly lower in CALD and AC patients (p<0.005). TBARS levels were significantly higher in CAH, CALD, and PBC patients (p<0.001, <0.02, and <0.001, respectively). In CAH patients, alcohol consumption correlated inversely with GSH and directly with TBARS (p<0.05). Patients with both CAH and alcohol abuse had a further reduction in liver GSH levels (p<0.005). Tissue levels of Fe were significantly increased in CALD and AC patients with respect to controls and CAH patients, whereas no significant difference was observed in Zn. These data confirm that patients with chronic ethanol exposure reveal a depletion in liver GSH content clearly correlated with an increase in lipid peroxidation and Fe liver storage. On the other hand, these findings appear to suggest no significant change in Zn levels in chronic hepatitis.