乳酸左氧氟沙星注射液内控质量标准的制定

目的：建立乳酸左氧氟沙星注射液内控质量标准。方法：依据该制剂法定质量标准,选择性状、鉴别、pH、颜色、左氧氟沙星含量作为内控质量检验项目,并同时采用紫外分光光度法和HPLC法对左氧氟沙星含量测定进行比较性试验。结果：制剂中左氧氟沙星的2种含量测定结果差异无统计学意义,可用紫外分光光度法代替HPLC法测定左氧氟沙星含量。结论：内控质量标准简单、快速、准确,适合于注射液中间品检验。     

Pre-ischemic treatment with memantine reversed the neurochemical and behavioural parameters but not energy metabolites in middle cerebral artery occluded rats

In the present study, Memantine (MN) an uncompetitive N-methyl-d-aspartate (NMDA) open channel blocker has been investigated for its suitable therapeutic time-window on the basis of its influence on behavioural and biochemical changes in rats subjected to transient focal ischemia. MN (20 mg/kg, ip) was administered at pre, during and post ischemic state and the extent of neuroprotection was compared to ascertain its therapeutic time-window in stroke treatment. Neuroprotective effect was assessed by measuring glutamate, glutamine synthetase, glutathione, Na⁺K⁺ATPase, adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide (NAD), lactate and pyruvate levels. Middle cerebral artery occlusion produced neurological deficits, anxiogenic behaviour, histological changes, increased glutamate levels along with depletion of Na⁺K⁺ATPase, energy stores such as ATP, NAD, lactate, and antioxidant glutathione. MN significantly restored glutamate, glutamine synthetase, Na⁺K⁺ATPase and lactate levels on preischemic administration. In addition, MN reversed the altered neurological and behavioural paradigms significantly and prevented the neurodegeneration on preischemic treatment. However, it failed to exert any effect on energy metabolite (ATP and NAD) levels irrespective of the treatment phase. Based on the present data, it is summarized that the suitable therapeutic time window of MN is preischemic phase in stroke and it possesses only a subjective role in reversing ischemic brain biochemical alterations preferentially in favor of neuronal homeostasis.     

Synergistic drug-cytokine induction of hepatocellular death as an in vitro approach for the study of inflammation-associated idiosyncratic drug hepatotoxicity

Idiosyncratic drug hepatotoxicity represents a major problem in drug development due to inadequacy of current preclinical screening assays, but recently established rodent models utilizing bacterial LPS co-administration to induce an inflammatory background have successfully reproduced idiosyncratic hepatotoxicity signatures for certain drugs. However, the low-throughput nature of these models renders them problematic for employment as preclinical screening assays. Here, we present an analogous, but high-throughput, in vitro approach in which drugs are administered to a variety of cell types (primary human and rat hepatocytes and the human HepG2 cell line) across a landscape of inflammatory contexts containing LPS and cytokines TNF, IFNγ, IL-1α, and IL-6. Using this assay, we observed drug-cytokine hepatotoxicity synergies for multiple idiosyncratic hepatotoxicants (ranitidine, trovafloxacin, nefazodone, nimesulide, clarithromycin, and telithromycin) but not for their corresponding non-toxic control compounds (famotidine, levofloxacin, buspirone, and aspirin). A larger compendium of drug-cytokine mix hepatotoxicity data demonstrated that hepatotoxicity synergies were largely potentiated by TNF, IL-1α, and LPS within the context of multi-cytokine mixes. Then, we screened 90 drugs for cytokine synergy in human hepatocytes and found that a significantly larger fraction of the idiosyncratic hepatotoxicants (19%) synergized with a single cytokine mix than did the non-hepatotoxic drugs (3%). Finally, we used an information theoretic approach to ascertain especially informative subsets of cytokine treatments for most highly effective construction of regression models for drug- and cytokine mix-induced hepatotoxicities across these cell systems. Our results suggest that this drug-cytokine co-treatment approach could provide a useful preclinical tool for investigating inflammation-associated idiosyncratic drug hepatotoxicity.     

Metabolic profiling studies on the toxicological effects of realgar in rats by H NMR spectroscopy

The toxicological effects of realgar after intragastrical administration (1 g/kg body weight) were investigated over a 21 day period in male Wistar rats using metabonomic analysis of ¹H NMR spectra of urine, serum and liver tissue aqueous extracts. Liver and kidney histopathology examination and serum clinical chemistry analyses were also performed. ¹H NMR spectra and pattern recognition analyses from realgar treated animals showed increased excretion of urinary Kreb's cycle intermediates, increased levels of ketone bodies in urine and serum, and decreased levels of hepatic glucose and glycogen, as well as hypoglycemia and hyperlipoidemia, suggesting the perturbation of energy metabolism. Elevated levels of choline containing metabolites and betaine in serum and liver tissue aqueous extracts and increased serum creatine indicated altered transmethylation. Decreased urinary levels of trimethylamine-N-oxide, phenylacetylglycine and hippurate suggested the effects on the gut microflora environment by realgar. Signs of impairment of amino acid metabolism were supported by increased hepatic glutamate levels, increased methionine and decreased alanine levels in serum, and hypertaurinuria. The observed increase in glutathione in liver tissue aqueous extracts could be a biomarker of realgar induced oxidative injury. Serum clinical chemistry analyses showed increased levels of lactate dehydrogenase, aspartate aminotransferase, and alkaline phosphatase as well as increased levels of blood urea nitrogen and creatinine, indicating slight liver and kidney injury. The time-dependent biochemical variations induced by realgar were achieved using pattern recognition methods. This work illustrated the high reliability of NMR-based metabonomic approach on the study of the biochemical effects induced by traditional Chinese medicine.     

Taurine prevents arsenic-induced cardiac oxidative stress and apoptotic damage: Role of NF-κB, p38 and JNK MAPK pathway

Cardiac dysfunction is a major cause of morbidity and mortality worldwide due to its complex pathogenesis. However, little is known about the mechanism of arsenic-induced cardiac abnormalities and the use of antioxidants as the possible protective agents in this pathophysiology. Conditionally essential amino acid, taurine, accounts for 25% to 50% of the amino acid pool in myocardium and possesses antioxidant properties. The present study has, therefore, been carried out to investigate the underlying mechanism of the beneficial role of taurine in arsenic-induced cardiac oxidative damage and cell death. Arsenic reduced cardiomyocyte viability, increased reactive oxygen species (ROS) production and intracellular calcium overload, and induced apoptotic cell death by mitochondrial dependent caspase-3 activation and poly-ADP ribose polymerase (PARP) cleavage. These changes due to arsenic exposure were found to be associated with increased IKK and NF-κB (p65) phosphorylation. Pre-exposure of myocytes to an IKK inhibitor (PS-1145) prevented As-induced caspase-3 and PARP cleavage. Arsenic also markedly increased the activity of p38 and JNK MAPKs, but not ERK to that extent. Pre-treatment with SP600125 (JNK inhibitor) and SB203580 (p38 MAPK inhibitor) attenuated NF-κB and IKK phosphorylation indicating that p38 and JNK MAPKs are mainly involved in arsenic-induced NF-κB activation. Taurine treatment suppressed these apoptotic actions, suggesting that its protective role in arsenic-induced cardiomyocyte apoptosis is mediated by attenuation of p38 and JNK MAPK signaling pathways. Similarly, arsenic intoxication altered a number of biomarkers related to cardiac oxidative stress and other apoptotic indices in vivo and taurine supplementation could reduce it. Results suggest that taurine prevented arsenic-induced myocardial pathophysiology, attenuated NF-κB activation via IKK, p38 and JNK MAPK signaling pathways and could possibly provide a protection against As-induced cardiovascular burden.     

Elevated glucose in pleural effusion: an early clue to esophageal perforation

Esophageal perforation is a rare cause of pleural effusions that carries with it a high mortality rate if diagnosis is delayed. The chemical characteristics of the pleural effusion include high amylase and low pH levels. However, these variables are nonspecific. We present a case of pleural effusion in a patient with markedly elevated glucose levels from recent cola ingestion as a specific clue to the diagnosis of esophageal perforation.     

Blood Lactate Measurements and Analysis during Exercise: A Guide for Clinicians

Blood lactate concentration ([La⁻]_b) is one of the most often measured parameters during clinical exercise testing as well as during performance testing of athletes. While an elevated [La⁻]_b may be indicative of ischemia or hypoxemia, it may also be a “normal” physiological response to exertion. In response to “all-out” maximal exertion lasting 30-120 seconds, peak [La⁻]_b values of ≈15–25 mM may be observed 3–8 minutes postexercise. In response to progressive, incremental exercise, [La⁻]_b increases gradually at first and then more rapidly as the exercise becomes more intense. The work rate beyond which [La⁻]_b increases exponentially [the lactate threshold (LT)] is a better predictor of performance than V˙O2max and is a better indicator of exercise intensity than heart rate; thus LT (and other valid methods of describing this curvilinear [La⁻]_b response with a single point) is useful in prescribing exercise intensities for most diseased and nondiseased patients alike. H⁺-monocarboxylate cotransporters provide the primary of three routes by which La⁻ transport proceeds across the sarcolemma and red blood cell membrane. At rest and during most exercise conditions, whole blood [La⁻] values are on average 70% of the corresponding plasma [La⁻] values; thus when analyzing [La⁻]_b'', care should be taken to both (1) validate the [La⁻]_b-measuring instrument with the criterion/reference enzymatic method and (2) interpret the results correctly based on what is being measured (plasma or whole blood). Overall, it is advantageous for clinicians to have a thorough understanding of [La⁻]_b responses, blood La⁻ transport and distribution, and [La⁻]_b analysis.     

Autoimmune modulation of astrocyte-mediated homeostasis

Astrocytes are principal mediators of homeostasis in the central nervous system (CNS). They supply neurons and oligodendrocytes with substrates for energy metabolism and clear the extracellular space of excess neurotransmitters. In neuroinflammation, astrocytes have classically been regarded as unimportant since their capacity to present antigen to T cells is limited and has been questioned in vivo. However, it is an evolving concept that autoimmunity in the CNS has a profound impact on astrocytes. In this review, we focus on the alterations in astrocyte functions that occur during an autoimmune attack of the CNS.     

Physiological correlates of performance. Case study of a world-class rower

This report describes the changes in physiological capacity of a heavy-weight rower who obtained seven medals in World Championships and Olympic Games. The investigation was carried out over the last 6 years of the rower’s international competition career in comparison with peer champions, and the following 4 years. Over the first period, maximal oxygen uptake () remained above 6 l min⁻¹ which is an outstanding value. The training load measured over the last 18 months of the period increased from 119 to 142 km wk⁻¹ of rowing. Four years after the international competition period, had only declined by 3.6% although the training load had declined by 35%. These data suggest that the ability of this rower to compete at top level for years was related to ability to maintain an outstanding . Gross efficiency and ability to rely on anaerobic glycolysis did not emerge as relevant factors.     

Linking supply to demand: the neuronal monocarboxylate transporter MCT2 and the α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionic acid receptor GluR2/3 subunit are associated in a common trafficking process

MCT2 is the major neuronal monocarboxylate transporter (MCT) that allows the supply of alternative energy substrates such as lactate to neurons. Recent evidence obtained by electron microscopy has demonstrated that MCT2, like α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionic acid (AMPA) receptors, is localized in dendritic spines of glutamatergic synapses. Using immunofluorescence, we show in this study that MCT2 colocalizes extensively with GluR2/3 subunits of AMPA receptors in neurons from various mouse brain regions as well as in cultured neurons. It also colocalizes with GluR2/3-interacting proteins, such as C-kinase-interacting protein 1, glutamate receptor-interacting protein 1 and clathrin adaptor protein. Coimmunoprecipitation of MCT2 with GluR2/3 and C-kinase-interacting protein 1 suggests their close interaction within spines. Parallel changes in the localization of both MCT2 and GluR2/3 subunits at and beneath the plasma membrane upon various stimulation paradigms were unraveled using an original immunocytochemical and transfection approach combined with three-dimensional image reconstruction. Cell culture incubation with AMPA or insulin triggered a marked intracellular accumulation of both MCT2 and GluR2/3, whereas both tumor necrosis factor α and glycine (with glutamate) increased their cell surface immunolabeling. Similar results were obtained using Western blots performed on membrane or cytoplasm-enriched cell fractions. Finally, an enhanced lactate flux into neurons was demonstrated after MCT2 translocation on the cell surface. These observations provide unequivocal evidence that MCT2 is linked to AMPA receptor GluR2/3 subunits and undergoes a similar translocation process in neurons upon activation. MCT2 emerges as a novel component of the synaptic machinery putatively linking neuroenergetics to synaptic transmission.