MDA, oxypurines, and nucleosides relate to reperfusion in short-term incomplete cerebral ischemia in the rat

Short-term incomplete cerebral ischemia (5 min) was induced in the rat by the bilateral clamping of the common carotid arteries. Reperfusion was obtained by removing carotid clamping and was carried out for the following 10 min. Animals were sacrificed either at the end of ischemia or reperfusion. Controls were represented by a group of sham-operated rats. Peripheral venous blood samples were withdrawn from the femoral vein from rats subjected to cerebral reperfusion 5 min before ischemia, at the end of ischemia, and 10 min after reperfusion. Neutralized perchloric acid extracts of brain tissue were analyzed by a highly sensitive high-performance liquid chromatography (HPLC) method for the direct determination of malondialdehyde, oxypurines, nucleosides, nicotinic coenzymes, and high-energy phosphates. In addition, plasma concentrations of malondialdehyde, hypoxanthine, xanthine, inosine, uric acid, and adenosine were determined by the same HPLC technique. Incomplete cerebral ischemia induced the appearance of a significant amount (8.05 nmol/g w.w.; SD = 2.82) of cerebral malondialdehyde (which was undetectable in control animals) and a decrease of ascorbic acid. A further 6.6-fold increase of malondialdehyde (53.30 nmol/g w.w.; SD = 17.77) and a 18.5% decrease of ascorbic acid occurred after 10 min of reperfusion. Plasma malondialdehyde, which was present in minimal amount before ischemia (0.050 mumol/L; SD = 0.015), significantly increased after 5 min of ischemia (0.277 mumol/L; SD = 0.056) and was strikingly augmented after 10 min of reperfusion (0.682 mumol/L; SD = 0.094). A similar trend was observed for xanthine, uric acid, inosine, and adenosine, while hypoxanthine reached its maximal concentration after 5 min of incomplete ischemia, being significantly decreased after reperfusion. From the data obtained, it can be concluded that tissue concentrations of malondialdehyde and ascorbic acid, and plasma levels of malondialdehyde, oxypurines, and nucleosides, reflect both the oxygen radical-mediated tissue injury and the depression of energy metabolism, thus representing early biochemical markers of short-term incomplete brain ischemia and reperfusion in the rat. In particular, these results suggest the possibility of using the variation of malondialdehyde, oxypurines, and nucleosides in peripheral blood as a potential biochemical indicator of reperfusion damage occurring to postischemic tissues

Decrease in n-acetylaspartate following concussion may be coupled to decrease in creatine

Objectives: To assess the time course changes in brain N-acetylaspartate (NAA) and creatine (Cr) in athletes who suffered a sport-related concussion. Participants: Eleven non-consecutive concussed athletes and 11 sex and age-matched control volunteers. Main outcome measures: At 3, 15, 30 and 45 days post-injury, athletes were examined by proton Magnetic Resonance Spectroscopy (1H-MRS) for the determination of NAA,(Cr) and choline (Cho). 1H-MRS data recorded in the control group were used for comparison. Results: Compared to controls (2.18 ± 0.19), athletes showed an NAA/Cr increase at 3 (2.71 ± 0.16; p < 0.01) and 15 days (2.54 ± 0.21; p < 0.01), followed by a decrease and subsequent normalization at 30 (1.95 ± 0.16, p < 0.05) and 45 days(2.17 ± 0.20; p <0.05) post-concussion. NAA/Cho decreased at 3, 15 and 30 days post-injury (p < 0.01 compared to controls), with no differences from controls at 45 days post-concussion. Significant increase in the Cho/Cr after 3 (+33%, p < 0.01) and 15 (+31.5%, p < 0.01) days post-injury was observed, whilst no differences compared to controls were recorded at 30 and 45 days post-impact. Conclusions: This cohort of athletes indicates that concussion may cause concomitant decrease in cerebral NAA and Cr. This occurrence provokes longer time of metabolism normalization, as well as longer resolution time of concussion-associated clinical symptoms

Adenine, guanine and pyridine nucleotides in blood during physical exercise and restitution in healthy subjects

Maximal physical exertion is accompanied by increased degradation of purine nucleotides in muscles with the products of purine catabolism accumulating in the plasma. Thanks to membrane transporters, these products remain in an equilibrium between the plasma and red blood cells where they may serve as substrates in salvage reactions, contributing to an increase in the concentrations of purine nucleotides. In this study, we measured the concentrations of adenine nucleotides (ATP, ADP, AMP), inosine nucleotides (IMP), guanine nucleotides (GTP, GDP, GMP), and also pyridine nucleotides (NAD, NADP) in red blood cells immediately after standardized physical effort with increasing intensity, and at the 30th min of rest. We also examined the effect of muscular exercise on adenylate (guanylate) energy charge—AEC (GEC), and on the concentration of nucleosides (guanosine, inosine, adenosine) and hypoxanthine. We have shown in this study that a standardized physical exercise with increasing intensity leads to an increase in IMP concentration in red blood cells immediately after the exercise, which with a significant increase in Hyp concentration in the blood suggests that Hyp was included in the IMP pool. Restitution is accompanied by an increase in the ATP/ADP and ADP/AMP ratios, which indicates an increase in the phosphorylation of AMP and ADP to ATP. Physical effort applied in this study did not lead to changes in the concentrations of guanine and pyridine nucleotides in red blood cells

Correlation between echocardiographic and hemodynamic variables in cardiothoracic intensive care unit

Objectives the echocardiographic indices have not been validated in critically ill population. We investigated the correlation between some echocardiographic and hemodynamics parameters. Design Prospective Spontaneous non-interventional observational study. Setting Adult cardiothoracic intensive care unit, single center (Royal Brompton Hospital, London UK). Participants Consecutive adult patients admitted to cardiothoracic intensive care unit for severe respiratory failure, primary cardio-circulatory failure and post-aortic surgery. Interventions Clinical, hemodynamic parameters (stroke volume – SV, cardiac output – CO, mean arterial pressure – MAP, and cardiac power index – CPI) and echocardiographic indices of ventricular function (left ventricular total isovolumic time – t-IVT, mitral annular plane systolic excursion – MAPSE, and left ventricular fraction – LVEF) were evaluated offline. Measurements and main results 117 patients were studied (age 57.2 ± 19; 60.6% male). t-IVT showed an inverse correlation with SV, CO, MAP and CPI (respectively r: -67%; -38%; -45%; -51%). MAPSE exhibited a positive correlation with SV, CO, MAP and CPI (respectively r: 43%; 44%; 34%; 31%). LVEF did not show any correlation. In the multivariate analysis the association of t-IVT and hemodynamics was confirmed for SV, CO, MAP and CPI with the highest partial correlation between t-IVT and MAP (R = -58%). Conclusions MAPSE and t-IVT are two reproducible and reliable echocardiographic indices of systolic function and ventricular efficacy associated with hemodynamic variables in cardiothoracic critically ill patients, while LVEF did not show any correlation

Sequence Specificity of BAL 31 Nuclease for ssDNA Revealed by Synthetic Oligomer Substrates Containing Homopolymeric Guanine Tracts

Background: The extracellular nuclease from Alteromonas espejiana, BAL 31 catalyzes the degradation of single-stranded and linear duplex DNA to 59-mononucleotides, cleaves negatively supercoiled DNA to the linear duplex form, and cleaves duplex DNA in response to the presence of apurinic sites. Principal Findings: In this work we demonstrate that BAL 31 activity is affected by the presence of guanine in singlestranded DNA oligomers. Specifically, nuclease activity is shown to be affected by guanine’s presence in minimal homopolymeric tracts in the middle of short oligomer substrates and also by its presence at the 39 end of ten and twenty base oligomers. GNC rich regions in dsDNA are known to cause a decrease in the enzyme’s nuclease activity which has been attributed to the increased thermal stability of these regions, thus making it more difficult to unwind the strands required for enzyme access. Our results indicate that an additional phenomenon could be wholly or partly responsible for the loss of activity in these GNC rich regions. Thus the presence of a guanine tract per se impairs the enzyme’s functionality, possibly due to the tract’s bulky nature and preventing efficient progression through the active site. Conclusions: This study has revealed that the general purpose BAL 31 nuclease commonly used in molecular genetics exhibits a hithertofore non-characterized degree of substrate specificity with respect to single-stranded DNA (ssDNA

Predicting functional impairment trajectories in amyotrophic lateral sclerosis: a probabilistic, multifactorial model of disease progression.

To employ Artificial Intelligence to model, predict and simulate the amyotrophic lateral sclerosis (ALS) progression over time in terms of variable interactions, functional impairments, and survival. We employed demographic and clinical variables, including functional scores and the utilisation of support interventions, of 3940 ALS patients from four Italian and two Israeli registers to develop a new approach based on Dynamic Bayesian Networks (DBNs) that models the ALS evolution over time, in two distinct scenarios of variable availability. The method allows to simulate patients' disease trajectories and predict the probability of functional impairment and survival at different time points. DBNs explicitly represent the relationships between the variables and the pathways along which they influence the disease progression. Several notable inter-dependencies were identified and validated by comparison with literature. Moreover, the implemented tool allows the assessment of the effect of different markers on the disease course, reproducing the probabilistically expected clinical progressions. The tool shows high concordance in terms of predicted and real prognosis, assessed as time to functional impairments and survival (integral of the AU-ROC in the first 36 months between 0.80-0.93 and 0.84-0.89 for the two scenarios, respectively). Provided only with measurements commonly collected during the first visit, our models can predict time to the loss of independence in walking, breathing, swallowing, communicating, and survival and it can be used to generate in silico patient cohorts with specific characteristics. Our tool provides a comprehensive framework to support physicians in treatment planning and clinical decision-making. [Abstract copyright: © 2022. The Author(s).

Extracellular tau oligomers affect extracellular glutamate handling by astrocytes through downregulation of GLT-1 expression and impairment of NKA1A2 function

Aims: Several studies reported that astrocytes support neuronal communication by the release of gliotransmitters, including ATP and glutamate. Astrocytes also play a fundamental role in buffering extracellular glutamate in the synaptic cleft, thus limiting the risk of excitotoxicity in neurons. We previously demonstrated that extracellular tau oligomers (ex-oTau), by specifically targeting astrocytes, affect glutamate-dependent synaptic transmission via a reduction in gliotransmitter release. The aim of this work was to determine if ex-oTau also impair the ability of astrocytes to uptake extracellular glutamate, thus further contributing to ex-oTau-dependent neuronal dysfunction. Methods: Primary cultures of astrocytes and organotypic brain slices were exposed to ex-oTau (200 nM) for 1&nbsp;h. Extracellular glutamate buffering by astrocytes was studied by: Na+ imaging; electrophysiological recordings; high-performance liquid chromatography; Western blot and immunofluorescence. Experimental paradigms avoiding ex-oTau internalisation (i.e. heparin pre-treatment and amyloid precursor protein knockout astrocytes) were used to dissect intracellular vs extracellular effects of oTau. Results: Ex-oTau uploading in astrocytes significantly affected glutamate-transporter-1 expression and function, thus impinging on glutamate buffering activity. Ex-oTau also reduced Na-K-ATPase activity because of pump mislocalisation on the plasma membrane, with no significant changes in expression. This effect was independent of oTau internalisation and it caused Na+ overload and membrane depolarisation in ex-oTau-targeted astrocytes. Conclusions: Ex-oTau exerted a complex action on astrocytes, at both intracellular and extracellular levels. The net effect was dysregulated glutamate signalling in terms of both release and uptake that relied on reduced expression of glutamate-transporter-1, altered function and localisation of NKA1A1, and NKA1A2. Consequently, Na+ gradients and all Na+-dependent transports were affected

Lack of effect of lowering LDL cholesterol on cancer: meta-analysis of individual data from 175,000 people in 27 randomised trials of statin therapy

&lt;p&gt;Background: Statin therapy reduces the risk of occlusive vascular events, but uncertainty remains about potential effects on cancer. We sought to provide a detailed assessment of any effects on cancer of lowering LDL cholesterol (LDL-C) with a statin using individual patient records from 175,000 patients in 27 large-scale statin trials.&lt;/p&gt; &lt;p&gt;Methods and Findings: Individual records of 134,537 participants in 22 randomised trials of statin versus control (median duration 4.8 years) and 39,612 participants in 5 trials of more intensive versus less intensive statin therapy (median duration 5.1 years) were obtained. Reducing LDL-C with a statin for about 5 years had no effect on newly diagnosed cancer or on death from such cancers in either the trials of statin versus control (cancer incidence: 3755 [1.4% per year [py]] versus 3738 [1.4% py], RR 1.00 [95% CI 0.96-1.05]; cancer mortality: 1365 [0.5% py] versus 1358 [0.5% py], RR 1.00 [95% CI 0.93–1.08]) or in the trials of more versus less statin (cancer incidence: 1466 [1.6% py] vs 1472 [1.6% py], RR 1.00 [95% CI 0.93–1.07]; cancer mortality: 447 [0.5% py] versus 481 [0.5% py], RR 0.93 [95% CI 0.82–1.06]). Moreover, there was no evidence of any effect of reducing LDL-C with statin therapy on cancer incidence or mortality at any of 23 individual categories of sites, with increasing years of treatment, for any individual statin, or in any given subgroup. In particular, among individuals with low baseline LDL-C (&#60;2 mmol/L), there was no evidence that further LDL-C reduction (from about 1.7 to 1.3 mmol/L) increased cancer risk (381 [1.6% py] versus 408 [1.7% py]; RR 0.92 [99% CI 0.76–1.10]).&lt;/p&gt; &lt;p&gt;Conclusions: In 27 randomised trials, a median of five years of statin therapy had no effect on the incidence of, or mortality from, any type of cancer (or the aggregate of all cancer).&lt;/p&gt