Novel use of matched filtering for synaptic event detection and extraction

Efficient and dependable methods for detection and measurement of synaptic events are important for studies of synaptic physiology and neuronal circuit connectivity. As the published methods with detection algorithms based upon amplitude thresholding and fixed or scaled template comparisons are of limited utility for detection of signals with variable amplitudes and superimposed events that have complex waveforms, previous techniques are not applicable for detection of evoked synaptic events in photostimulation and other similar experimental situations. Here we report on a novel technique that combines the design of a bank of approximate matched filters with the detection and estimation theory to automatically detect and extract photostimluation-evoked excitatory postsynaptic currents (EPSCs) from individually recorded neurons in cortical circuit mapping experiments. The sensitivity and specificity of the method were evaluated on both simulated and experimental data, with its performance comparable to that of visual event detection performed by human operators. This new technique was applied to quantify and compare the EPSCs obtained from excitatory pyramidal cells and fast-spiking interneurons. In addition, our technique has been further applied to the detection and analysis of inhibitory postsynaptic current (IPSC) responses. Given the general purpose of our matched filtering and signal recognition algorithms, we expect that our technique can be appropriately modified and applied to detect and extract other types of electrophysiological and optical imaging signals.     

The level of Hsp27 in lymphocytes is negatively associated with a higher risk of lung cancer

Heat shock proteins (Hsps) can protect cells, organs, and whole organisms against damage caused by abnormal environmental hazards. Some studies have reported that lymphocyte Hsps may serve as biomarkers for evaluating disease status and exposure to environmental stresses; however, few epidemiologic studies have examined the associations between lymphocyte Hsps levels and lung cancer risk. We examined lymphocyte levels of Hsp27 and Hsp70 in 263 lung cancer cases and age- and gender-matched cancer-free controls by flow cytometry. Multivariate logistic regression models were used to estimate the association between lymphocyte Hsps levels and lung cancer risk. Our results showed that Hsp27 levels were significantly lower in lung cancer cases than in controls (16.5 vs 17.8 mean fluorescence intensity, P < 0.001). This was not observed for Hsp70 levels. Further stratification analysis revealed that lymphocyte Hsp27 levels were negatively associated with lung cancer risk especially in males and heavy smokers. There was a statistical trend of low odd ratios (95% confidence intervals) and upper tertile levels of Hsp27 [1.000, 0.904 (0.566–1.444) and 0.382 (0.221–0.658, P _trend = 0.001) in males and 1.000, 0.9207 (0.465–1.822) and 0.419 (0.195–0.897, P _trend = 0.036) in heavy smokers] after adjustment for confounding factors. These results suggest that lower lymphocyte Hsp27 levels might be associated with an increased risk of lung cancer. Our findings need to be validated in a large prospective study. Feng Wang and Maohui Feng contributed equally to this work.     

Potential of DNMT and its Epigenetic Regulation for Lung Cancer Therapy

Lung cancer, the leading cause of mortality in both men and women in the United States, is largely diagnosed at its advanced stages that there are no effective therapeutic alternatives. Although tobacco smoking is the well established cause of lung cancer, the underlying mechanism for lung tumorigenesis remains poorly understood. An important event in tumor development appears to be the epigenetic alterations, especially the change of DNA methylation patterns, which induce the most tumor suppressor gene silence. In one scenario, DNA methyltransferase (DNMT) that is responsible for DNA methylation accounts for the major epigenetic maintenance and alternation. In another scenario, DNMT itself is regulated by the environment carcinogens (smoke), epigenetic and genetic information. DNMT not only plays a pivotal role in lung tumorigenesis, but also is a promising molecular bio-marker for early lung cancer diagnosis and therapy. Therefore the elucidation of the DNMT and its related epigenetic regulation in lung cancer is of great importance, which may expedite the overcome of lung cancer.Key Words: Lung cancer, epigenetic regulation, DNA methylation, DNMT, gene silence, epigenetic therapy.     

Effects of Dietary Pb on Accumulation,Histopathology, and Digestive Enzyme Activities in the Digestive System of Tilapia (<Emphasis Type="Italic">Oreochromis niloticus</Emphasis>)

With the increasing occurrence of dietary lead (Pb) contamination in aquatic environment, threat of the dietary Pb toxicity to aquatic organisms attracted more attention. In this study, after being exposed to dietary Pb at concentrations of 0, 100, 400, and 800-μg/g dry weight for 60 days, the groups of tilapia (Oreochromis niloticus) were sacrificed and sampled to analyze the effects of dietary Pb on accumulation, histopathology, and digestive enzyme activities in tissues of the digestive system. The results showed that the Pb accumulation in tissues increased with the dietary Pb concentrations. Moreover, Pb accumulated in sampled tissues in the following order: intestine > stomach > liver. By observation of liver histological sections in optical microscope, lesions could be detected in the Pb-contaminated groups. It was also demonstrated that the inhibitory effect of dietary Pb on digestive enzyme activities was dietary Pb concentration dependent. Different degrees of inhibition of enzyme activities were exhibited in sampled tissues. It was indicated that digestive enzyme activities in the digestive system might be considered as the potential biomarkers of dietary Pb contamination in tilapia.     

Increase of plasma IL-6 concentration with age in healthy subjects.

The present study demonstrated that plasma IL-6 concentration was higher in older subjects than in younger ones and significantly in the male group (P = 0.02); Spearman rank correlation showed that plasma IL-6 concentration was positively correlated with age (r = 0.28, N = 55, P < 0.05); there was a highly significant correlation between the concentrations in plasma IL-6 and IL-1 alpha (r = 0.51, N = 52, P < 0.001). These findings suggest the possibility that age-related changes of plasma IL-6 and IL-1 alpha may provide a pathological basis for the susceptibility to such illness as commonly occurs in elderly people, especially Alzheimer's disease as the two interleukins can induce the production of alpha 1-antichymotrypsin and beta-amyloid protein precursor.     

Human insulin from a precursor overexpressed in the methylotrophic yeast Pichia pastoris and a simple procedure for purifying the expression product

The methylotrophic yeast Pichia pastoris, which proved successful in producing many heterologous proteins, was used to express an insulin precursor. A transformant with a high copy number of the gene integrated into the chromosome was obtained by the dot-blotting method. In high-density fermentation using a simple culture medium composed mainly of salt and methanol, the expression level reached 1.5 g/L. A simple two-step method was established to purify the expression product from the culture medium with an overall recovery of about 80%. After tryptic transpeptidation, human insulin with full receptor binding capacity and biological activity was obtained. In the presence of zinc, the recombinant human insulin could be crystallized in the rhombohedral form.     

Purified PTP1 protein induces antigen-specific protective immunity against Encephalitozoon cuniculi

Microsporidiosis poses a problem for immunocompromised individuals including patients with HIV infection as well as those with organ transplantation. Recent reports from Africa have suggested that microsporidiosis with diarrhea is an independent risk factor for malnutrition in children. Previous studies from our laboratory have demonstrated that CD8⁺ T cells are an essential component of protective immunity against the microsporidium Encephalitozoon cuniculi. Mutant mice lacking this T cell subset or cytotoxic function are unable to clear the infection and ultimately succumb to the disease. However, information regarding the antigens involved in the elicitation of CD8⁺ T cell response is not available. In this study, we report that immunization of animals with Encephalitozoon hellem polar tube protein 1 (rEhPTP1) induces a strong T cell response in vaccinated animals. Splenic dendritic cells pulsed with rEhPTP1 are able to induce E. cuniculi specific CD8⁺ T cell response with no effect on the CD4⁺ T cell subset. This is the first report identifying a protein capable of inducing CD8⁺ T cell immunity, which is conserved in other microsporidial species of human importance.     

H2AX phosphorylation regulated by p38 is involved in Bim expression and apoptosis in chronic myelogenous leukemia cells induced by imatinib

Increasing evidence suggests that histone H2AX plays a critical role in regulation of tumor cell apoptosis and acts as a novel human tumor suppressor protein. However, the action of H2AX in chronic myelogenous leukemia (CML) cells is unknown. The detailed mechanism and epigenetic regulation by H2AX remain elusive in cancer cells. Here, we report that H2AX was involved in apoptosis of CML cells. Overexpression of H2AX increased apoptotic sensitivity of CML cells (K562) induced by imatinib. However, overexpression of Ser139-mutated H2AX (blocking phosphorylation) decreased sensitivity of K562 cells to apoptosis. Similarly, knockdown of H2AX made K562 cells resistant to apoptotic induction. These results revealed that the function of H2AX involved in apoptosis is strictly related to its phosphorylation (Ser139). Our data further indicated that imatinib may stimulate mitogen-activated protein kinase (MAPK) family member p38, and H2AX phosphorylation followed a similar time course, suggesting a parallel response. H2AX phosphorylation can be blocked by p38 siRNA or its inhibitor. These data demonstrated that H2AX phosphorylation was regulated by p38 MAPK pathway in K562 cells. However, the p38 MAPK downstream, mitogen- and stress-activated protein kinase-1 and -2, which phosphorylated histone H3, were not required for H2AX phosphorylation during apoptosis. Finally, we provided epigenetic evidence that H2AX phosphorylation regulated apoptosis-related gene Bim expression. Blocking of H2AX phosphorylation inhibited Bim gene expression. Taken together, these data demonstrated that H2AX phosphorylation regulated by p38 is involved in Bim expression and apoptosis in CML cells induced by imatinib.