Comparative effects of acute-methionine loading on the plasma sulfur-amino acids in NAC-supplemented HIV+ patients and healthy controls.

In this study, an acute overloading of methionine (MetLo) was used to investigate the trassulfuration pathway response comparing healthy controls and HIV+ patients under their usual diet and dietary N-acetyl-L-cysteine (NAC) supplementation. MetLo (0.1 g Met/kg mass weight) was given after overnight fasting to 20 non-HIV+ control subjects (Co) and 12 HIV+ HAART-treated patients. Blood samples were taken before and after the MetLo in two different 7-day dietary situations, with NAC (1 g/day) or with their usual diet (UD). The amino acids (Met, Hcy, Cys, Tau, Ser, Glu and Gln) and GSH were determined by HPLC and their inflow rate into circulation (plasma) was estimated by the area under the curve (AUC). Under UD, the HIV+ had lower plasma GSH and amino acids (excepting Hcy) and higher oxidative stress (GSSG/GSH ratio), similar remethylation (RM: Me/Hcy + Ser ratio), transmethylation (TM; Hcy/Met ratio) and glutaminogenesis (Glu/Gln ratio), lower transsulfuration (TS: Cys/Hcy + Ser ratio) and Cys/Met ratio and, higher synthetic rates of glutathione (GG: GSH/Cys ratio) and Tau (TG: Tau/Cys ratio). NAC supplementation changed the HIV pattern by increasing RM above control, normalizing plasma Met and TS and, increasing plasma GSH and GG above controls. However, plasma Cys was kept always below controls probably, associatively to its higher consumption in GG (more GSSG than GSH) and TG. The failure of restoring normal Cys by MetLo, in addition to NAC, in HIV+ patients seems to be related to increased flux of Cys into GSH and Tau pathways, probably strengthening the cell-antioxidant capacity against the HIV progression (registered at http://www.clinicaltrials.gov , NCT00910442).

Plasma glutathione of HIV⁺ patients responded positively and differently to dietary supplementation with cysteine or glutamine.

OBJECTIVE: Patients with positivity for the human immunodeficiency virus (HIV⁺) present low concentrations of antioxidant nutrients, including total glutathione (GSH) and its precursors. We investigated the responses of the sulfur-containing amino acid pathway to cysteine and glutamine (Gln) dietary supplements in patients with HIV⁺ compared with healthy controls. METHODS: Twelve treated patients (six men and six women, 22-45 y old) and 20 healthy controls (10 men and 10 women, 20-59 y old) were randomly assigned to 7-d dietary supplements containing N-acetylcysteine (NAC; 1 g/d) or Gln (20 g/d), with a 7-d washout period ingesting their usual diet. Blood samples were drawn after an overnight fast. High-performance liquid chromatographic plasma analysis of sulfur-containing amino acids (methionine, homocysteine, cysteine, and taurine), GSH, oxidized GSH, and serine, glycine, glutamic acid, and Gln was carried out moments before and after 7-d supplementations. Statistical comparisons were undertaken between groups and between dietary supplements (P < 0.05). RESULTS: Patients with HIV⁺ showed higher oxidized GSH and lower concentrations of GSH and all amino acids except homocysteine. The HIV⁺ group responded to the NAC by increased levels of sulfur-containing amino acids and GSH and equalized taurine and GSH levels in the control group. The Gln supplements also equalized the levels of GSH, Gln, and glycine in the control group. CONCLUSION: An increase in GSH may be attained by NAC or Gln supplementation, with NAC acting by increasing cysteine levels and Gln likely acting by replenishing the glycine pool (trial registered at http://www.clinicaltrials.gov, identifier NCT00910442).

Impacto do exercício muscular exaustivo sobre indicadores sanguíneos em praticantes de musculação / Impact of exercising muscles to exhaustion on blood markers in weight-training

O impacto da exaustão (com pesos) de grupos musculares, sobre indicadores sanguíneos de acidose e de hemoconcentração foi estudado em 8 jovens (20-30 anos) treinados em musculação. Todos foram submetidos a sobrecarga inicial de 80% de 1RM, até a exaustão (TE), em 8 exercícios distintos, com coleta de sangue e registro da freqüência cardíaca (FC) antes (At) e imediatamente após (Ap) o TE para a determinação da glicemia, indicadores hemogasimétricos: pH, lactato (lac), NH4+, pO2, pCO2, HCO-3 e ácido úrico (AU) e hemoconcentração: hematócrito, hemoglobina, sódio (Na+) e cloreto (Cl-). O efeito da exaustão (At/Ap) sobre cada variável foi testado pelo teste t (Student) e a comparação entre os exercícios pela ANOVA (one way) para alfa = 0,05. A elevação da FC por kg levantado ocorreu de forma decrescente: rosca direta, triceps pulley e mesa flexora, maiores (p < 0,05) que elevação lateral, puxador alto, supino, Hack e fl exão plantar do tornozelo em pé na máquina. Com o TE observou-se, nos 8 exercícios, redução significativa do pH e HCO-3 e elevações do lac e NH4+. Os exercícios com maior número de variáveis alteradas (7 a 9) foram: rosca direta, puxador alto, supino e mesa flexora e com menor número de alterações os exercícios flexão plantar do tornozelo em pé na máquina e Hack. Estes últimos foram discriminados por NH4+, lac, e HCO-3. Assim o estado de exaustão, com repercussões sanguíneas sistêmicas foi atingido mais rapidamente com exercícios rosca direta e mesa flexora do que os exercícios Hack e flexão plantar do tornozelo.

Metabolic markers of physical exhaustion were evaluated in venous blood drawn from 8 men (20-30 years old)with at least 3 years? experience in weight-lifting training. They were submitted, in the morning, to an overload (exhaustion) test starting at 80% of 1 RM (one repetition maximum) on 8 muscle groups. Heart rate (HR) was measured and samples of venous blood were collected before and immediately after the exhaustion test (ET) and sent to a laboratory for blood gas analysis (pH, lactate, pO2, pCO2 and HCO-3) and measurement of electrolytes (Na+, Cl-, K+ and Ca++) and glycemia. The HR/kg ratios observed were in the following sequence of descending order: arm and hamstrings > shoulder and back > chest > quadriceps > calf. Results for NH4, pH, lactate and HCO-3 levels were changed in all 8 muscle groups, whereas Ca++, K+, Na+, Cl-, and uric acid did not change signifi cantly after the ET. The muscle groups: back, biceps, triceps, chest, and hamstrings exhibited changes in seven to nine indicators while only 4 to 6 biochemical indicators changed in response to shoulder, calf, and quadriceps exercises. Thus, blood markers indicating acidosis, hemoconcentration and hyperglycemia were sensitive markers although with low specificity for the eight muscle groups. Calf and quadriceps had the highest tolerance for weight loading along with the smallest HR increase and lowest number of biochemical indicators changed. Therefore, it appears possible to reach muscle exhaustion with systemic responses in the blood by working out the arm muscles and hamstrings with lighter weights than for quadriceps and calf muscles.