The Multi-Drug Resistant Tuberculosis Diagnosis and Treatment Cascade in Bangladesh

Objectives

To determine, in areas supported by BRAC, Bangladesh i) the pre-diagnosis and pre-treatment attrition among presumptive and confirmed Multi-Drug Resistant Tuberculosis (MDR-TB) patients and ii) factors associated with attrition.

Methods

This was a retrospective cohort study involving record review. Presumptive MDR-TB patients from peripheral microscopy centres serving 60% of the total population of Bangladesh were included in the study. Attrition and turnaround time for MDR-TB diagnosis by Xpert MTB/RIF and treatment initiation were calculated between July 2012 and June 2014.

Results

Of 836 presumptive MDR-TB patients referred from 398 peripheral microscopy centres, 161 MDR-TB patients were diagnosed. The number of diagnosed MDR-TB patients was less than country estimates of MDR-TB patients (2000 cases) during the study period. Among those referred, pre-diagnosis and pre-treatment attrition was 17% and 21% respectively. Median turnaround time for MDR-TB testing, result receipt and treatment initiation was four, zero and five days respectively. Farmers (RR=2.3, p=0.01) and daily wage laborers (RR=2.1, p=0.04) had twice the risk of having pre-diagnosis attrition. Poor record-keeping and unreliable upkeep of presumptive MDR-TB patient databases were identified as challenges at the peripheral microscopy centres.

Conclusion

There was a low proportion of pre-diagnosis and pre-treatment attrition in patients with presumptive and confirmed MDR-TB under programmatic conditions. However, the recording and reporting system did not detect all presumptive MDR-TB patients, highlighting the need to improve the system in order to prevent morbidity, mortality and transmission of MDR-TB in the community.     

Extracellular polysaccharides of cowpea rhizobia: compositional and functional studies

Polysaccharides excreted by cowpea Rhizobium strains JLn(c) and RA-1 were mixtures of complex acidic exopolysaccharides and low molecular weight neutral glucans. These polymers were fractionated using gel filtration chromatography. Purified fractions of the acidic heteropolymer reacted with peanut agglutinin to give precipitin bands when subjected to Ouchterlony gel diffusion. The acidic exopolysaccharide was found to contain mainly glucose, galactose, glucuronic acid, mannose and fucose. The non-carbohydrate substituents of the acidic heteropolymer were pyruvate, acetate and uronate which were identified by infrared and proton nuclear magnetic resonance spectroscopy as well as by chemical analysis.Abbreviations EPS Extracellular polysaccharide - YEM yeast extract mannitol - PNA peanut agglutination - ¹H-NMR proton nuclear magnetic resonance     

Investigating the influence of electrode Miller indices alteration on electronic transport in thiophene-based molecular junctions

Electrical charge transport through thiophene-dithiol-based molecular wires attached to gold electrodes with three different types of crystallographic orientations (<1,1,1>, <1,1,0 >?and <1,0,1?>) was investigated. Electron transport in the systems under consideration was evaluated systematically by analyzing current values, transmission spectrum, projected device density of states and zero bias orbital analysis utilizing density functional theory in conjunction with non-equilibrium Green’s function. Investigations proved that tuning of conductance in nano-molecular junctions is possible through different electrode orientations. As the HOMO–LUMO gap in the <1,1,0?>?oriented thiophene dithiol junction is drastically less than that of the other configurations under consideration, the <1,1,0?> configuration exhibited superior constructive conductance in comparison to other junction orientations. This provided us with ideas for designing pioneering hetero-cyclic nano-scale electronics devices. Also, <1,1,0?>?has been found to show negative differential conductance behavior above +2.6 V and below ?2.6 V, and hence has potential applications in oscillating and switching circuits.     

A truncated form of DNA topoisomerase IIbeta associates with the mtDNA genome in mammalian mitochondria.

Despite the likely requirement for a DNA topoisomerase II activity during synthesis of mitochondrial DNA in mammals, this activity has been very difficult to identify convincingly. The only DNA topoisomerase II activity conclusively demonstrated to be mitochondrial in origin is that of a type II activity found associated with the mitochondrial, kinetoplast DNA network in trypanosomatid protozoa [Melendy, T., Sheline, C., and Ray, D.S. (1988) Cell 55, 1083-1088; Shapiro, T.A., Klein, V.A., and Englund, P.A. (1989) J. Biol. Chem.264, 4173-4178]. In the present study, we report the discovery of a type DNA topoisomerase II activity in bovine mitochondria. Identified among mtDNA replicative proteins recovered from complexes of mtDNA and protein, the DNA topoisomerase relaxes a negatively, supercoiled DNA template in vitro, in a reaction that requires Mg2+ and ATP. The relaxation activity is inhibited by etoposide and other inhibitors of eucaryotic type II enzymes. The DNA topoisomerase II copurifies with mitochondria and directly associates with mtDNA, as indicated by sensitivity of some mtDNA circles in the isolated complex of mtDNA and protein to cleavage by etoposide. The purified activity can be assigned to a approximately 150-kDa protein, which is recognized by a polyclonal antibody made against the trypanosomal mitochondrial topo II enzyme. Mass spectrometry performed on peptides prepared from the approximately 150-kDa protein demonstrate that this bovine mitochondrial activity is a truncated version of DNA topoisomerase IIbeta, one of two DNA topoisomerase II activities known to exist in mammalian nuclei.     

Androgen-metabolizing enzymes show region-specific changes across the breeding season in the brain of a wild songbird.

The Lapland longspur (Calcarius lapponicus) is an arctic-breeding songbird that shows rapid behavioral changes during a short breeding season. Changes in plasma testosterone (T) in the spring are correlated with singing but not territorial aggression in males. Also, T treatment increases song but not aggression in this species. In contrast, in temperate-zone breeders, song and aggression are highly correlated, and both increase after T treatment. We asked whether regional or temporal differences in androgen-metabolizing enzymes in the longspur brain explain hormone-behavior patterns in this species. We measured the activities of aromatase, 5alpha-reductase and 5beta-reductase in free-living longspur males. Aromatase and 5alpha-reductase convert T into the active steroids 17beta-estradiol (E(2)) and 5alpha-dihydrotestosterone (5alpha-DHT), respectively. 5beta-Reductase deactivates T via conversion to 5beta-DHT, an inactive steroid. We examined seven brain regions at three stages in the breeding season. Overall, aromatase activity was high in the hypothalamus, hippocampus, and ventromedial telencephalon (containing nucleus taeniae, the avian homologue to the amygdala). 5beta-Reductase activity was high throughout the telencephalon. Activities of all three enzymes changed over time in a region-specific manner. In particular, aromatase activity in the rostral hypothalamus was decreased late in the breeding season, which may explain why T treatment at this time does not increase aggression. Changes in 5beta-reductase do not explain the effects of plasma T on aggressive behavior.     

Application of cell culture toxicity tests to the development of implantable biosensors

Cell culture toxicity testing methods were modified and applied to the development of implantable glucose microsensors, and positive and negative control materials suitable for the microsensor assessment were established. The location, source and degree of the toxic effect in a multi-component biosensor was spatially visualized with cell monolayers. A freshly prepared sensor showed moderate toxicity, mainly as a result of the presence of glutaraldehyde and the residual solvents in the polymer layers. However, it was possible to reduce the toxicity by removing the leachable toxic substances through extraction in phosphate, buffer, and a non-toxic sensor was readily obtained.     

Influence of aminophylline on the lipids in Microsporum gypseum.

The effect of aminophylline on the lipid synthesis of Microsporum gypseum has been examined. A decreased incorporation of [14C]acetate into lipids was observed when the cells were incubated for 1 h with aminophylline which was reflected in all the individual lipid fractions. However, cells grown with aminophylline in the growth medium exhibited increased levels of total phospholipids, which was probably due to a rise in intracellular cAMP as these cells exhibited 4-fold increased levels of cAMP. Decreased activity of phosphodiesterase by aminophylline accounts for the increased cAMP levels. Increased phospholipid content in aminophylline grown cells was further supported by the increased incorporation of [14C]acetate into phospholipids as well as increased activities of phospholipid biosynthetic enzymes in comparison to non-supplemented cells.     

Role of P2X7 purinoceptors in neuroprotective mechanism of ischemic postconditioning in mice

Cerebral ischemia–reperfusion (I–R) injury is one of the primary causes of ischemic stroke. Ischemic postconditioning (iPoCo) is evolving as an important adaptive technique to contain I–R injury. Some recent studies have shown neuroprotective effect of iPoCo. However, neuroprotective mechanism of iPoCo is not clear. So, the present study has been undertaken to investigate the possible role of P2X7 purinoceptors in neuroprotective mechanism of iPoCo in mice. Bilateral carotid artery occlusion for 12 min followed by R for 24 h produced a significant rise in cerebral infarct size and neurological severity score (NSS) along with impairment of memory and motor coordination. iPoCo, involving three episodes of 10-s carotid artery occlusion with intermittent R of 10 s applied just after ischemic insult of 12 min, produced a significant decrease in cerebral infarct size and NSS along with reversal of I–R-induced impairment of memory and motor coordination. iPoCo induced neuroprotective effects were significantly abolished by pretreatment with selective purinergic P2X7 receptor blocker Brilliant Blue G (40 mg/kg intraperitoneal). It may be concluded that neuroprotective effect of iPoCo probably involves in activation of purinergic P2X7 receptors.     

Development of an assay to measure mutagenic non-homologous end-joining repair activity in mammalian cells

Double-strand break (DSB) repair pathways are critical for the maintenance of genomic integrity and the prevention of tumorigenesis in mammalian cells. Here, we present the development and validation of a novel assay to measure mutagenic non-homologous end-joining (NHEJ) repair in living cells, which is inversely related to canonical NHEJ and is based on the sequence-altering repair of a single site-specific DSB at an intrachromosomal locus. We have combined this mutagenic NHEJ assay with an established homologous recombination (HR) assay such that both pathways can be monitored simultaneously. In addition, we report the development of a ligand-responsive I-SceI protein, in which the timing and kinetics of DSB induction can be precisely controlled by regulating protein stability and cellular localization in cells. Using this system, we report that mutagenic NHEJ repair is suppressed in growth-arrested and serum-deprived cells, suggesting that end-joining activity in proliferating cells is more likely to be mutagenic. Collectively, the novel DSB repair assay and inducible I-SceI will be useful tools to further elucidate the complexities of NHEJ and HR repair.