The radiation inactivation method provides evidence that membrane-bound mitochondrial creatine kinase is an oligomer

Lyophilized suspensions of rabbit heart mitochondria have been irradiated with varying doses of gamma rays. Mitochondrial creatine kinase activity was inactivated exponentially with a radiation inactivation size of 352 or 377 kDa depending upon the initial medium. These values are in good agreement with the molecular mass previously deduced from by permeation experiments: 357 kDa. This is the first direct evidence showing that the native form of mitochondrial creatine kinase is associated to the inner membrane as an oligomer, very likely an octamer.     

Autoreactive T cells in mercury-induced autoimmunity. Ability to induce the autoimmune disease

It has been previously shown that autoreactive T cells appear during mercury-induced autoimmunity in Brown-Norway (BN) rats. In the present work, it is shown that: 1) T cells and T helper cells from HgCl2-injected BN rats are able to actively transfer autoimmunity in normal BN rats; the disease transferred is exacerbated when recipients are treated with the antisuppressor/cytotoxic T cell monoclonal antibody (OX8); 2) normal T cells preincubated with HgCl2 are also able to transfer the disease in OX8-treated but not in T cell-depleted rats; and 3) T cells from HgCl2-injected BN rats also transferred the disease in both normal and T cell depleted rats. It is concluded that: 1) autoreactive T cells, and presumably anti-Ia T cells are involved in the pathogenesis of mercury-induced autoimmunity; 2) these autoreactive T cells induce suppressor/cytotoxic T cells to proliferate in normal syngeneic recipients; the fact that this T cell subset did not proliferate in HgCl2-injected BN rats suggests that HgCl2 also affects T suppressor cells; and 3) mercury-induced autoimmunity could result from the additive effect of the emergence of autoreactive T cells and of a defect at the T suppressor level.     

Biochemical,genetic and molecular characterization of new respiratory-deficient mutants inChlamydomonas reinhardtii

Eight respiratory-deficient mutants ofChlamydomonas reinhardtii have been isolated after mutagenic treatment with acriflavine or ethidium bromide. They are characterized by their inability to grow or their very reduced growth under heterotrophic conditions. One mutation (Class III) is of nuclear origin whereas the seven remaining mutants (Classes I and II) display a predominantly paternalmt ^- inheritance, typical of mutations residing in the mitochondrial DNA. Biochemical analysis has shown that all mutants are deficient in the cyanide-sensitive cytochrome pathway of the respiration whereas the alternative pathway is still functional. Measurements of complexes II + III (antimycin-sensitive succinate-cytochromec oxido-reductase) and complex IV (cytochromec oxidase) activities allowed to conclude that six mutations have to be localized in the mitochondrial apocytochromeb (COB) gene, one in the mitochondrial cytochrome oxidase subunit I (COI) gene and one in a nuclear gene encoding a component of the cytochrome oxidase complex. By using specific probes, we have moreover demonstrated that five mutants (Class II mutants) contain mitochondrial DNA molecules deleted in the terminal end containing the COB gene and the telomeric region; they also possess dimeric molecules resulting from end-to-end junctions of deleted monomers. The two other mitochondrial mutants (Class I) have no detectable gross alteration. Class I and Class II mutants can also be distinguished by the pattern of transmission of the mutation in crosses.Anin vivo staining test has been developed to identify rapidly the mutants impaired in cyanide-sensitive respiration.     

Can we afford screening for neural tube defects? The South Wales experience.

Clinical and financial gains and losses accruing from five different options for screening for open neural tube defects were estimated, based principally on the results of detailed monitoring of inputs and outcomes and of process costs in the South Wales Anencephaly and Spina Bifida Study. As well as estimating the overall clinical costs of a screening service it was shown that if the prevalence, including terminations, of open neural tube defects is between 1.25 and five per 1000 births the financial cost of avoiding the birth of a seriously handicapped child who would survive for more than 24 hours is in the range 9000 pounds- 54000 pounds depending on the option adopted and the prevalence of the condition in the target population. Prevalence is the biggest determinant of cost. The data should provide a basis for assessment and discussion of resource priorities in the National Health Service.     

Ecdysteroid receptors in a tumorous blood cell line of Drosophila melanogaster

The tumorous Drosophila melanogaster blood cell line BII has been studied for evidence for the presence of ecdysteroid receptors. The [³H]ponasterone A (pon A)* used in this study has been extensively purified, and the location of the tritium in the molecule has been partially determined. BII cells do not metabolise ecdysteroids. Intact cells demonstrate a considerable specific uptake of [³H]pon A which is saturable, apparently showing two specific components: a very high affinity component (K_D = 0.3 nM) and a high affinity component (K_D = 2 nM). The specific binding of [³H]pon A to whole cells is compatible with unlabelled ecdysteroids, but not with mammalian steroid hormones. The association rate constant (k_a) for [³H]pon A was determined to be 3 × 10⁷M^?1min^?1 at 21 °C, while the dissociation rate constant (k_d) for the specifically bound [³H]pon A was found to be 4.4 × 10^?3/min. Together, the kinetic rate constants yield a value of 0.15 nM for the K_D. The receptors have been partially characterised in a cell-free extract prepared by sonification of the cells. The optimum pH for extraction and hormone binding is 8.2. Scatchard plots of binding data indicate that the cell-free extract also contains two high affinity specific binding components (k_D = 0.1 nM and K_D = 1 nM). The hgih affinity binders are macromolecular, as shown by chromatography on Sephadex G-25, and are susceptible to protease digestion, heat, and treatment with N-ethylmaleimide. Sucrose density centrifugation of the labelled receptor shows one peak at approximately 6S. The stability of the receptor preparation has been studied and conditions have been empirically determined (10% w/v sucrose, 25 mM dithioerthreitol, and 10 mM citrate), whereby the binding capacity of the unlabelled receptor is stable for at least 8 weeks if frozen at ?20°C.     

Hepatitis C in Laos: A 7-Year Retrospective Study on 1765 Patients

Hepatitis C virus(HCV) is a global health concern, notably in Southeast Asia, and in Laos the presentation of the HCVinduced liver disease is poorly known. Our objective was thus to describe a comprehensive HCV infection pattern in order to guide national health policies. A study on a group of 1765 patients formerly diagnosed by rapid test in health centres was conducted at the Centre of Infectiology Lao Christophe Merieux in Vientiane. The demographic information of patients,their infection status(viral load: VL), liver function(aminotransferases) and treatments were analysed. Results showed that gender distribution of infected people was balanced; with median ages of 53.8 for men and 51.6 years for women(13–86 years). The majority of patients(72%) were confirmed positive(VL [ 50 IU/mL) and 28% of them had high VL([ 6 log10). About 23% of patients had level of aminotransferases indicative of liver damage([ 40 IU/m L); but less than20% of patients received treatment. Patients rarely received a second sampling or medical imaging. The survey also showed that cycloferon, pegylated interferon and ribavirin were the drugs prescribed preferentially by the medical staff,without following any international recommendations schemes. In conclusion, we recommend that a population screening policy and better management of patients should be urgently implemented in the country, respecting official guidelines.However, the cost of biological analysis and treatment are significant barriers that must be removed. Public health resolutions should be immediately enforced in the perspective of meeting the WHO HCV elimination deadline by 2030.     

Candida species in tchapalo and bangui, two traditional alcoholic beverages from Côte d'Ivoire

The increase of infections due to non-Candida albicans species made it very necessary to conduct adequate characterization to be able to identify the species of Candida isolated from traditional fermented foods. In this study, based on their hue on Candida Chromogenic Agar medium, a total of 136 yeast strains were isolated from tchapalo and bangui. Molecular identification based on PCR-RFLP of internal transcribed spacers of rDNA (ITS) and sequencing of the ITS and the D1/D2 regions allowed us to assign these isolates to seven species: Candida tropicalis, Candida inconspicua, Candida rugosa, Saccharomyces cerevisiae, Kluyveromyces marxianus, Hanseniaspora guilliermondii, Trichosporon asahii. With the respect to each beverage, six species were found among with four species are regarded as opportunistic pathogens. From these, C. tropicalis, C. inconspicua and K. marxianus were the most commonly encountered. The enzyme activities of the potential pathogens assessed using API ZYM system showed that almost strains had esterase, esterase lipase, valine and cystine arylamidase, alpha chymotrypsin, alkaline phosphatase and naphthol phosphohydrolase activities. The activity of α-glucosidase was found only in C. tropicalis and C. inconspicua strains isolated from tchapalo while β-glucosidase activity was found in all strains from tchapalo and only in C. inconspicua isolated from bangui.     

Effects of UV-C radiation on <Emphasis Type="Italic">Chlorella vulgaris</Emphasis>, a biofilm-forming alga

Photosynthetic biofilms proliferating on heritage monuments represent a major threat for curators leading to biodegradation and esthetic issues. Previous studies demonstrated that UV-C, used as a tool for biofilm eradication, is a promising avenue to combat microbial proliferation. In this study, this environmentally friendly method was tested on biofilm-forming Chlorella vulgaris suspension. Algal physiological response to UV-C was then assessed. Results showed that >?10 kJ m^?2 UV-C exposure was enough to directly kill cells whereas low UV-C exposure reduced quantum yield of photosystem II and inhibited both respiration and photosynthesis. Clear relationships between UV-C exposure times and physiological responses were found. In addition, the use of VIS-light after UV-C treatment enhances chlorophyll bleaching. Our findings contribute to a better understanding of the physiological responses of Chlorella vulgaris to UV-C radiation allowing thus an optimization of the UV-C treatment reported in our previous studies.