Pore formation is not associated with macroscopic redistribution of P2X7 receptors

The present study examines whether changes in P2X7 purinergic receptor density precede formation of the cytolytic pore characteristic of this receptor. We fused P2X7 receptors with enhanced green fluorescent protein (EGFP) at the amino or carboxy termini (EGFP-P2X7 and P2X7-EGFP). Electrophysiological characterization in Xenopus oocytes revealed wild-type responses to ATP for GFP-tagged receptors. However, differences in sensitivity to ATP were apparent with the P2X7-EGFP receptor displaying a threefold reduction in ATP sensitivity compared with control. Ethidium ion uptake was used to measure cytolytic pore formation. Comparison of tagged receptors with wild type in HEK-293 and COS-7 cells showed there was no significant difference in ethidium ion uptake, suggesting that fusions with EGFP did not interfere with cytolytic pore formation. Confocal microscopy confirmed that tagged receptors localized to the plasmalemma. Simultaneous monitoring of EGFP and ethidium ion fluorescence revealed that changes in receptor distribution do not precede pore formation. We conclude that it is unlikely that large scale changes in P2X7 receptor density precede pore formation.     

Neurotoxicity of fluoride: neurodegeneration in hippocampus of female mice

Light microscopic study of hippocampal sub-regions demonstrated significant number of degenerated nerve cell bodies in the CA3, CA4 and dentate gyrus(Dg) areas of sodium fluoride administered adult female mice. Ultrastructural studies revealed neurodegenrative characteristics like involution of cell membranes, swelling of mitochondria, clumping of chromatin material etc, can be observed in cell bodies of CA3, CA4 and dentate gyrus (Dg). Fluoride intoxicated animals also performed poorly in motor co-ordination tests and maze tests. Inability to perform well increased with higher fluoride concentration in drinking water.     

Development of cloning vectors and transformation methods for<Emphasis Type="Italic"> Amycolatopsis</Emphasis>

The genus Amycolatopsis is of industrial importance, as its species are known to produce commercial antibiotics. It belongs to the family Pseudonocardiaceae and has an eventful taxonomic history. Initially strains were identified as Streptomyces, then later as Nocardia. However, based on biochemical, morphological and molecular features, the genus Amycolatopsis, containing seventeen species, was created. The development of molecular genetic techniques for this group has been slow. The scarcity of molecular genetic tools including stable plasmids, antibiotic resistance markers, transposons, reporter genes, cloning vectors, and high efficiency transformation protocols has made progress slow, but efforts in the past decade have led to the development of cloning vectors and transformation methods for these organisms. Some of the cloning vectors have broad host range (pRL series) whereas others have limited host range (pMEA300 and pMEA100). The cloning vector pMEA300 has been completely sequenced, while only the minimal replicon (pA-rep) has been sequenced from pRL plasmids. Direct transformation of mycelia and electroporation are the most widely applicable methods for transforming species of Amycolatopsis. Conjugational transfer from Escherichia coli has been reported only in the species A. japonicum, and gene disruption and replacements using homologous recombination are now possible in some strains. Electronic Publication     

Hybrid methods for automated diagnosis of breast tumors

OBJECTIVE: To design and analyze a new family of hybrid methods for the diagnosis of breast tumors using fine needle aspirates. STUDY DESIGN: We present a radically new approach to the design of diagnosis systems. In the new approach, a nonlinear classifier with high sensitivity but low specificity is hybridized with a linear classifier having low sensitivity but high specificity. Data from the Wisconsin Breast Cancer Database are used to evaluate, computationally, the performance of the hybrid classifiers. RESULTS: The diagnosis scheme obtained by hybridizing the nonlinear classifier ellipsoidal multisurface method (EMSM) with the linear classifier proximal support vector machine (PSVM) was found to have a mean sensitivity of 97.36% and a mean specificity of 95.14% and was found to yield a 2.44% improvement in the reliability of positive diagnosis over that of EMSM at the expense of 0.4% degradation in the reliability of negative diagnosis, again compared to EMSM. At the 95% confidence level we can trust the hybrid method to be 96.19-98.53% correct in its malignant diagnosis of new tumors and 93.57-96.71% correct in its benign diagnosis. CONCLUSION: Hybrid diagnosis schemes represent a significant paradigm shift and provide a promising new technique to improve the specificity of nonlinear classifiers without seriously affecting the high sensitivity of nonlinear classifiers.     

An improved method for the determination of green and black tea polyphenols in biomatrices by high-performance liquid chromatography with coulometric array detection

Tea polyphenols are strong antioxidants and are believed to have beneficial health effects. However, the blood and tissue levels of these compounds are not well characterized because of a lack of suitable analytical methods for the biological resolution of these compounds. Previously, we developed methods for the analysis of three green tea catechins. Now we report an improved method for the measurement of the levels of the different catechins and theaflavins in biological fluids and tissues. The method includes digestion of the plasma, urine, or tissue samples with beta-d-glucuronidase and sulfatase, followed by extraction with ethyl acetate and subsequent separation by reversed-phase high-performance liquid chromatography (HPLC). The polyphenols are identified on the basis of their retention times, spectral analysis, and electrochemical behavior across an array of electrodes. In a single HPLC run, it is possible to determine the major catechins and theaflavins as well as some of the catechin metabolites. The detection limits for catechins and theaflavins are from 5 to 10 ng/ml of saliva, plasma, or urine.     

Characterization of cytochrome P450 2A4 and 2A5-catalyzed 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) metabolism

The tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), is a potent lung carcinogen in the A/J mouse, and is believed to be a causative agent for human lung cancer. NNK requires metabolic activation by alpha-hydroxylation to exert its carcinogenic potential. The human P450, 2A6 is a catalyst of this reaction. There are two closely related enzymes in the mouse, P450 2A4 and 2A5, which differ from each other by only 11 amino acids. In the present study these two mouse P450s were expressed in Spodoptera frugiperda (Sf9) cells using recombinant baculovirus. The catalysis of NNK metabolism by Sf9 microsomal fractions containing either P450 2A4 or 2A5 was determined. Both enzymes catalyzed the alpha-hydroxylation of NNK but with strikingly different efficiencies and specificities. P450 2A5 preferentially catalyzed NNK methyl hydroxylation, while P450 2A4 preferentially catalyzed methylene hydroxylation. The KM and Vmax for the former were 1.5 microM and 4.0 nmol/min/nmol P450, respectively, and for the latter 3.9 mM and 190 nmol/min/nmol P450. The mouse coumarin 7-hydroxylase, P450 2A5 is a significantly better catalyst of NNK alpha-hydroxylation than is the closely related human enzyme, P450 2A6.     

Absolute Leukocyte Telomere Length in HIV-Infected and Uninfected Individuals: Evidence of Accelerated Cell Senescence in HIV-Associated Chronic Obstructive Pulmonary Disease

Combination antiretroviral therapy (cART) has extended the longevity of human immunodeficiency virus (HIV)-infected individuals. However, this has resulted in greater awareness of age-associated diseases such as chronic obstructive pulmonary disease (COPD). Accelerated cellular senescence may be responsible, but its magnitude as measured by leukocyte telomere length is unknown and its relationship to HIV-associated COPD has not yet been established. We measured absolute telomere length (aTL) in peripheral leukocytes from 231 HIV-infected adults. Comparisons were made to 691 HIV-uninfected individuals from a population-based sample. Subject quartiles of aTL were assessed for relationships with measures of HIV disease severity, airflow obstruction, and emphysema severity on computed tomographic (CT) imaging. Multivariable regression models identified factors associated with shortened aTL. Compared to HIV-uninfected subjects, the mean aTL in HIV-infected patients was markedly shorter by 27 kbp/genome (p<0.001); however, the slopes of aTL vs. age were not different (p=0.469). Patients with longer known durations of HIV infection (p=0.019) and lower nadir CD4 cell counts (p=0.023) had shorter aTL. Shorter aTL were also associated with older age (p=0.026), smoking (p=0.005), reduced forced expiratory volume in one second (p=0.030), and worse CT emphysema severity score (p=0.049). HIV-infected subjects demonstrate advanced cellular aging, yet in a cART-treated cohort, the relationship between aTL and age appears no different from that of HIV-uninfected subjects.     

WNT1-inducible signaling pathway protein-1 activates diverse cell survival pathways and blocks doxorubicin-induced cardiomyocyte death

The anthracycline antibiotic doxorubicin (DOX) is a potent cancer chemotherapeutic agent that exerts both acute and chronic cardiotoxicity. Here we show that in adult mouse cardiomyocytes, DOX activates (i) the pro-apoptotic p53, (ii) p38MAPK and JNK, (iii) Bax translocation, (iv) cytochrome c release, and (v) caspase 3. Further, it (vi) inhibits expression of anti-apoptotic Akt, Bcl-2 and Bcl-xL, and (vii) induces internucleosomal degradation and cell death. WNT1-inducible signaling pathway protein-1 (WISP1), a CCN family member and a matricellular protein, inhibits DOX-mediated cardiomyocyte death. WISP1 inhibits DOX-induced p53 activation, p38 MAPK and JNK phosphorylation, Bax translocation to mitochondria, and cytochrome c release into cytoplasm. Additionally, WISP1 reverses DOX-induced suppression of Bcl-2 and Bcl-xL expression and Akt inhibition. The pro-survival effects of WISP1 were recapitulated by the forced expression of mutant p53, wild-type Bcl-2, wild-type Bcl-xL, or constitutively active Akt prior to DOX treatment. WISP1 also induces the pro-survival factor Survivin via PI3K/Akt signaling. Overexpression of wild-type, but not mutant Survivin, blunts DOX cytotoxicity. Further, WISP1 stimulates PI3K–Akt-dependent GSK3β phosphorylation and β-catenin nuclear translocation. Importantly, WISP1 induces its own expression. Together, these results provide important insights into the cytoprotective effects of WISP1 in cardiomyocytes, and suggest a potential therapeutic role for WISP1 in DOX-induced cardiotoxicity.