Solvent effects on the helix–coil transition in polypeptides

A simple way to incorporate the solvent–peptide interaction in any available theory of the helix–coil transition is developed. The competition between the intramolecular hydrogen bonding and the solvent–polymer hydrogen bonding is considered in multi-component solvents where some of the components have hydrogen-bonding capacity. Molecular averages are computed by using the theory of Lifson and Roig. The experimental data of Yang are analyzed, and the range of acceptable values of the equilibrium constants of hydrogen bond formation is deduced. The enthalpy of the transition in multicomponent solvents is calculated.     

Enzymology of mammalian phospholipases D: in vitro studies

The existence of multiple forms of phopholipase D was clearly established in a large number of biochemical studies that described and characterized the enzymological properties of the different PLD activities. This review summarizes the in vitro evidence showing differential subcellular localization and chromatographic properties of putative PLD isozymes, their phospholipid and alcohol substrate specificities, their modulation by various divalent cations, small G proteins and protein kinase c isozymes, and the role of phosphatidylinositol 4,5-bisphosphate as a cofactor of phospholipase D.     

Monitoring of viral cancer progression using FTIR microscopy: a comparative study of intact cells and tissues

Fourier transform infrared microspectroscopy (FTIR-MSP) is an analytical method with a promising potential for detecting the spectral changes due to cancerous changes in cells. The purpose of the present study is monitoring biochemical spectral changes accompanying viral cancer progression in cells and tissues using FTIR-MSP. As a model system, we used cells in culture which were transformed to malignant cells by infection with murine sarcoma virus (MuSV) and cervical tissues at different neoplastic stages. In order to devise a systematic follow-up of the cancer progression, it was essential first to determine and validate consistent and significant spectral biomarkers, which can evidently discriminate between normal and cancerous cells/tissues. Then these biomarkers were used for the characterization and classification of early stages of malignant transformation utilizing discriminant classification function techniques. Our study points out that malignancy progression can be eminently graded for both cell lines and tissues. For example, using the array of four biomarkers: A(2958)A(2852)+A(2923),A(1121)/A(1015),A(1171)/A(1152)and|A(1082)-A(1056)|A(1028), we attained that the classification accuracies of different premalignant stages of cell lines and tissues were varied between 89.5 and 97.4%. These results strongly support the potential of developing FTIR microspectroscopy as a simple, reagent free method for early detection and accurate differentiation of premalignant stages.     

Novel spectral method for the study of viral carcinogenesis in vitro

Fourier transform infrared (FTIR) spectroscopy is a unique technique for the laboratory diagnosis of cellular variations based on the characteristic molecular vibrational spectra of the cells. Microscopic FTIR was used to investigate spectral differences between normal and malignant fibroblasts transformed by retrovirus infection. A detailed analysis showed significant differences between cancerous and normal cells. The contents of vital cellular metabolites were significantly lower in the transformed cells than in the normal cells. In an attempt to identify the cellular components responsible for the observed spectral differences between normal and cancerous cells, we found significant differences between DNA of normal and cancerous cells.     

Four USH2A founder mutations underlie the majority of Usher syndrome type 2 cases among non-Ashkenazi Jews

Type 2 Usher syndrome (USH2) is a recessively inherited disorder, characterized by the combination of early onset, moderate-to-severe, sensorineural hearing loss, and vision impairment due to retinitis pigmentosa. From 74% to 90% of USH2 cases are caused by mutations of the USH2A gene. USH2A is composed of 72 exons, encoding for usherin, an extracellular matrix protein, which plays an important role in the development and maintenance of neurosensory cells in both retina and cochlea. To date, over 70 pathogenic mutations of USH2A have been reported in individuals of various ethnicities. Many of these mutations are rare private mutations segregating in single families. The aim of the current work was to investigate the genetic basis for USH2 among Jews of various origins. We found that four USH2A mutations (c.239-240insGTAC, c.1000C>T, c.2209C>T, and c.12067-2A>G) account for 64% of mutant alleles underlying USH2 in Jewish families of non-Ashkenazi descent. Considering the very large size of the USH2A gene and the high number of mutations detected in USH2 patients worldwide, our findings have significant implications for genetic counseling and carrier screening in various Jewish populations.     

Genetic carrier screening for spinal muscular atrophy and spinal muscular atrophy with respiratory distress 1 in an isolated population in Israel

Spinal muscular atrophy (SMA) is an autosomal recessive disease characterized by progressive muscle weakness. It is caused by a mutation in the survival motor neuron gene 1 (SMN1) gene. SMA with respiratory distress 1 (SMARD1), an uncommon variant of infantile SMA also inherited in an autosomal recessive manner, is caused by mutations in the immunoglobulin mu-binding protein 2 (IGHMBP2) gene. We carried out genetic carrier screening among the residents of an isolated Israeli Arab village with a high frequency of SMA in order to identify carriers of SMA type I and SMARD1. During 2006, 168 women were tested for SMA, of whom 13.1% were found to be carriers. Of 111 women tested for SMARD1, 9.9% were found to be carriers. Prenatal diagnosis was performed in one couple where both spouses were carriers of SMARD1; the fetus was found to be affected, and the pregnancy was terminated. To the best of our knowledge, this is the first example of the establishment of a large-scale carrier-screening program for SMA and SMARD1 in an isolated population. SMA has a carrier frequency of 1:33-1:60 in most populations and should be considered for inclusion in a population-based genetic-screening program.     

A meta-analysis of the incidence of malignancy in adult patients with rheumatoid arthritis

Introduction

The risk of malignancies in patients with rheumatoid arthritis (RA) has raised some concern, particularly with immunosuppressive approaches to disease management.

Methods

We conducted a systematic review of the literature and meta-analysis characterizing the associated risk of overall malignancy and four site-specific malignancies (lymphoma, lung, colorectal, and breast cancer) in patients with RA. A Medline search from 1990 to 2007 was conducted using specified search terms and predefined inclusion criteria for identification of relevant observational studies that provide estimates of relative risk of malignancy associated with RA. Study-specific estimates of the relative risk, as measured by standardized incidence ratios (SIRs) and estimated in comparison with the general population, were combined using a random effects model.

Results

A total of 21 publications were identified, of which 13 reported the SIR for overall malignancy, 14 for lymphoma, 10 for colorectal, 12 for lung, and 9 for breast cancer. Compared with the general population, the overall SIR estimates suggest that RA patients have approximately a two-fold increase in lymphoma risk (SIR 2.08, 95% confidence interval [CI] 1.80 to 2.39) and greater risk of Hodgkin than non-Hodgkin lymphoma. The risk of lung cancer was also increased with an SIR of 1.63 (95% CI 1.43 to 1.87). In contrast, a decrease in risk was observed for colorectal (SIR 0.77, 95% CI 0.65 to 0.90) and breast (SIR 0.84, 95% CI 0.79 to 0.90) cancer. The SIR for overall malignancy was 1.05 (95% CI 1.01 to 1.09).

Conclusion

Patients with RA appear to be at higher risk of lymphoma and lung cancer and potentially decreased risk for colorectal and breast cancer compared with the general population.     

Cardioprotective and antioxidant effects of apomorphine

Apomorphine is a potent antioxidant that infiltrates through biological membranes. We studied the effect of apomorphine (2 microM) on myocardial ischemic-reperfusion injury in the isolated rat heart. Since iron and copper ions (mediators in formation of oxygen-derived free radicals) are released during myocardial reperfusion, apomorphine interaction with iron and copper and its ability to prevent copper-induced ascorbate oxidation were studied. Apomorphine perfused before ischemia or at the commencement of reperfusion demonstrated enhanced restoration of hemodynamic function (i.e. recovery of the work index (LVDP x HR) was 69.2 +/- 4.0% with apomorphine pre-ischemic regimen vs. 43.4 +/- 9.01% in control hearts, p < 0.01, and 76.3 +/- 8.0% with apomorphine reperfusion regimen vs. 30.4 +/- 11.1% in controls, p < 0.001). This was accompanied by decreased release of proteins in the effluent and improved coronary flow recovery in hearts treated with apomorphine after the ischemia. Apomorphine forms stable complexes with copper and with iron, and inhibits the copper-induced ascorbate oxidation. It is suggested that these iron and copper chelating properties and the redox-inactive chelates formed by transition metals and apomorphine play an essential role in post-ischemic cardioprotection.