Mitochondrial associated metabolic proteins are selectively oxidized in A30P alpha-synuclein transgenic mice--a model of familial Parkinson's disease

Parkinson's disease (PD) is the most common neurodegenerative movement disorder and is characterized by the loss of dopaminergic neurons in the substantia nigra compacta. alpha-Synuclein is strongly implicated in the pathophysiology of PD because aggregated alpha-synuclein accumulates in the brains of subjects with PD, mutations in alpha-synuclein cause familial PD, and overexpressing mutant human alpha-synuclein (A30P or A53T) causes degenerative disease in mice or drosophila. The pathophysiology of PD is poorly understood, but increasing evidence implicates mitochondrial dysfunction and oxidative stress. To understand how mutations in alpha-synuclein contribute to the pathophysiology of PD, we undertook a proteomic analysis of transgenic mice overexpressing A30P alpha-synuclein to investigate which proteins are oxidized. We observed more than twofold selective increases in specific carbonyl levels of three metabolic proteins in brains of symptomatic A30P alpha-synuclein mice: carbonic anhydrase 2 (Car2), alpha-enolase (Eno1), and lactate dehydrogenase 2 (Ldh2). Analysis of the activities of these proteins demonstrates decreased functions of these oxidatively modified proteins in brains from the A30P compared to control mice. Our findings suggest that proteins associated with impaired energy metabolism and mitochondria are particularly prone to oxidative stress associated with A30P-mutant alpha-synuclein.     

Admission lactate level and the APACHE II score are the most useful predictors of prognosis following torso trauma

BACKGROUND: Markers of dysoxic metabolism and scoring systems for triage have been widely used in critically injured patients. However, so far, no model is sufficiently reliable to predict the outcome in trauma victims. The purposes of the present study, therefore, were to determine whether a correlation exits between the main trauma scoring systems and the markers of dysoxic metabolism. Moreover, to assess if any of the admission parameters can be used to indicate outcome. METHODS: Sixty-four patients were included in this study. Admission data, including arterial lactate level, base deficit (BD), pH, revised trauma score (RTS), injury severity score (ISS), shock index (SI), and Acute Physiology and Chronic Health Evaluation (APACHE II), were collected and analysed by logistic regression analysis. Degree of association between continuous variables were calculated by either Pearson's or Spearman's correlation coefficient, where applicable. The dependence of lactate on two or more other variables was evaluated by multiple linear regression analysis. RESULTS: Logistic regression analysis showed that the fatal outcome following major torso trauma was principally associated with the APACHE II score and lactate. The specificity and the sensitivity of this logistic regression model was 94.6 and 79.2%, respectively. According to standardised linear regression coefficients, BD was the best single predictor of lactate, and APACHE II added a small amount of predictive power. The proportion of total variation in lactate level explained by base deficit, APACHE II and age is R2=85.2%. CONCLUSION: APACHE II score and the arterial lactate level are the most important determinants of clinical outcome in critically injured patients. A correlation exits between lactate and APACHE II and between lactate and base deficit.     

Blockade of quinolinic acid-induced neurotoxicity by pyruvate is associated with inhibition of glial activation in a model of Huntington's disease

In this study, we have examined the mechanisms involved in pyruvate-mediated neuroprotection against quinolinic acid (QA)-induced striatal damage. QA injection into the striatum caused widespread neuronal damage and extensive areas of lesions in core and penumbra. The involvement of oxidative-mediated striatal damage was suggested by increased expressions of peroxynitrite, marked lipid peroxidation, and formation of DNA oxidative damage products. Administration of pyruvate, a glycolysis end product with antioxidant activity, significantly reduced QA-mediated striatal lesions, neuronal degeneration, and oxidative damage, whereas another energy substrate, lactate, was ineffective against oxidative damage and only partially effective in reducing lesions and neuronal degeneration. Treatment with the iNOS inhibitor aminoguanidine attenuated QA-mediated striatal lesions and reduced oxidative damage, indicating that iNOS activation may be involved in the striatal oxidative damage induced by QA. A role for glial cells in mediating oxidative damage was suggested because pyruvate blocked the expression of iNOS and nitrotyrosine in activated microglia and astrocytes in QA-injected striatum. These data suggest that pyruvate reduces oxidative free radical damage in QA-injected striatum and could have clinical utility in the treatment of Huntington's disease (HD).     

Limiting factors to oxygen transport on Mount Everest 30 years after: a critique of Paolo Cerretelli’s contribution to the study of altitude physiology

In 1976, Paolo Cerretelli published an article entitled Limiting factors to oxygen transport on Mount Everest in the Journal of Applied Physiology . The paper demonstrated the role of cardiovascular oxygen transport in limiting maximal oxygen consumption (O_2max). In agreement with the predominant view of O_2max limitation at that time, however, its results were taken to mean that cardiovascular oxygen transport does not limit O_2max at altitude. So it was argued that the limiting factor could be in the periphery, and muscle blood flow was proposed as a possible candidate. Despite this suggestion, the conclusion generated a series of papers on muscle structural characteristics. These experiments demonstrated a loss of muscle oxidative capacity in chronic hypoxia, and thus provided an unambiguous refutation of the then widespread hypothesis that an increased muscle oxidative capacity is needed at altitude to compensate for the lack of oxygen. This analysis is followed by a short account of Cerretellis more recent work, with a special attention to the subject of the so-called lactate paradox.     

Influence of caffeine, cold and exercise on multiple choice reaction time

RATIONALE: The effects of caffeine on psychomotor performance have been evaluated under resting conditions and in a thermoneutral environment. Our hypothesis was that these effects could be modified by factors enhancing the level of alertness, such as exercise and cold exposure. OBJECTIVE: The purpose of this study was to follow up changes in the multiple choice reaction time (RT) during exercise at room and low ambient temperatures after caffeine or placebo administered in a double blind manner. METHODS: Nine soccer players performed multistage, incremental exercise until volitional exhaustion on a bicycle ergometer at 22 degrees C or 4 degrees C, 1 h after ingestion of coffee with caffeine (CAF) or without it (PL). Immediately before exercise and at the end of each workload, RT and blood lactate (LA) were measured. Oxygen uptake (VO2) and heart rate (HR) were recorded continuously. Blood LA threshold and the workload associated with the shortest RT were determined. RESULTS: During exercise at 22 degrees C, RT was significantly shorter in CAF than in the PL test, while at 4 degrees C there were no differences in RT between CAF and PL trials. Cold exposure did not affect RT either at rest or during exercise. Neither caffeine nor cold exposure influenced the maximal VO2, the maximal HR and LA threshold. CONCLUSION: In the thermoneutral environment, caffeine ingestion improved psychomotor performance during exercise, whilst at low ambient temperature this effect was blunted. These findings suggest that the stimulating action of caffeine depends on the level and source of arousal.     

Quantitative changes of metabolic and bioenergetic parameters in experimental tumors during fractionated irradiation

Purpose: Previous studies with rat rhabdomyosarcomas indicate that during fractionated irradiation profound alterations of the tumor microvasculature and the oxygenation status occur when the total dose exceeds 45 Gy. At this dose a destruction which included all structures of the vessels and a significant worsening in tumor oxygenation were found. The aim of the present study was to analyze whether these effects of fractionated irradiation on the microvasculature and on tumor oxygenation also induce changes in the bioenergetic and metabolic status in the tumors during radiation treatment.

Methods and Materials: R1H rhabdomyosarcomas of the rat implanted into the flank were irradiated with ⁶⁰Co-γ-rays using 5 fractions of 3 Gy per week over 5 weeks. During this irradiation schedule, tumors were investigated each week for the microregional distributions of glucose, lactate, and ATP concentrations. For this, tumors were rapidly excised, shock-frozen and quantitative bioluminescence measurements were performed on tumor tissue sections.

Results: ATP concentrations remained unchanged during fractionated irradiation up to a total dose of 45 Gy. Above this dose, a significant decrease in ATP levels was observed. Lactate concentrations changed only slightly during irradiation whereas glucose levels increased continuously over the whole irradiation period.

Conclusions: During fractionated irradiation of R1H tumors with a total dose of 75 Gy, the bioenergetic and metabolic status of the tumors changed considerably. This became most obvious once a dose of 45 Gy had been achieved. The severe energy depletion and worsening of tumor oxygenation might be the result of destruction of tumor blood vessels as has been described previously in the same tumor model. The modification of the tumor micromilieu appears to be an important parameter in the responsiveness of tumor cells to radiation and for local tumor control.     

17β‐hydroxysteroid dehydrogenases in normal human mammary epithelial cells and breast tissue

17hydroxysteroid dehydrogenase activity represents a group of several isoenzymes (17HSDs) that catalyze the interconversion between highly active 17hydroxy and low activity 17ketosteroids and thereby regulate the biological activity of sex steroids. The present study was carried out to characterize the expression of 17HSD isoenzymes in human mammary epithelial cells and breast tissue. In normal breast tissues 17HSD types 1 and 2 mRNAs were both evenly expressed in glandular epithelium. In two human mammary epithelial cell lines, mRNAs for 17HSD types 1, 2 and 4 were detected. In enzyme activity measurements only oxidative 17HSD activity, corresponding to either type 2 or type 4 enzyme, was present. The role of 17HSD type 4 in estrogen metabolism was further investigated, using several cell lines originating from various tissues. No correlation between the presence of 17HSD type 4mRNA and 17HSD activity in different cultured cell lines was detected. Instead, oxidative 17HSD activity appeared in cell lines where 17HSD type 2 was expressed and reductive 17HSD activity was present in cells expressing 17HSD type 1. These data strongly suggest that in mammary epithelial cell lines the oxidative activity is due to type 2 17HSD and that oxidation of 17hydroxysteroids is not the primary activity of the 17HSD type 4 enzyme.     

恶性疟原虫乳酸脱氢酶的快速电泳法检测及影响因素

目的建立一种敏感、特异的恶性疟快速诊断方法。方法：应用快速电泳法检测恶性疟病人血样中恶性疟原虫乳酸脱氢酶（ＬＤＨ－Ｐ），并对可能影响检测结果的几种因素进行观察。结果：检测４０份恶性疟病人血样，３８份检测出ＬＤＨ－Ｐ，阳性率为９５％，假阴性率为５％；同时检测４０份间日疟病人血样和２０份正常人血样，均为阴性，无假阳性；血样反复冻融可使ＬＤＨ－Ｐ受到破坏，蛋白酶抑制剂对保存血样中的ＬＤＨ－Ｐ保护作用明显；新鲜血样中加否蛋白酶抑制剂，检测结果差异不明显。结论：快速电泳法检测ＬＤＨ－Ｐ诊断恶性疟，方法简便、敏感性和特异性高，具有很好的现场应用价值。检测新鲜血样中ＬＤＨ－Ｐ效果好。     

The effects of graded exercise on plasma proenkephalin peptide F and catecholamine responses at sea level

Summary The purpose of this study was to evaluate the effects of graded treadmill exercise on plasma preproenkephalin peptide F immunoreactivity and concomitant catecholamine responses at sea level (elevation, 50 m). Few data exist regarding the sea-level responses of plasma peptide F immunoreactivity to exercise. Thirty-five healthy men performed a graded exercise test on a motor-driven treadmill at the relative exercise intensities of 25, 50, 75, and 100% of maximum oxygen consumption (VO_2max). Significant (P<0.05) increases above rest were observed for plasma peptide F immunoreactivity and norepinephrine at 75 and 100% of the VO_2max and at 5 min into recovery. Significant increases in plasma epinephrine were observed at 75 and 100% of VO_2max. Whole blood lactate significantly increased above resting values at 50, 75, and 100% of the VO_2max and at 5 min into recovery. These data demonstrate that exercise stress increases plasma peptide F immunoreactivity levels at sea level. While the exercise response patterns of peptide F immunoreactivity are similar to catecholamines and blood lactate responses, no bivariate relationships were observed. These data show that sea-level response patterns to graded exercise are similar to those previously observed at moderate altitude (elevation, 2200 m).Human subjects participated in these studies after giving their free and informed voluntary consent. Investigators adhered to AR 70-25 and USAMRDC regulation 70-25 on Use of Volunteers in Research. The views, opinion, and/or findings contained in this report are those of the author(s) and should not be construed as an official Department of the Army position, policy, or decision, unless to designated by other official documentation.