An Observational Case-Control Study to Determine Human Immunodeficiency Virus and Host Factor Influence on Biomarker Distribution and Serodiagnostic Potential in Adult Pulmonary Tuberculosis

Influence of host factors, including human immunodeficiency virus (HIV) co-infection, on the distribution and diagnostic potential of previously evaluated biomarkers of pulmonary tuberculosis (PTB), such as anti-antigen 60 (A60) immunoglobulin (Ig) G, anti-A60 IgA, and C-reactive protein (CRP), remain unclear. Anti-A60 IgG, anti-A60 IgA, and CRP in PTB and non-PTB patient sera (n = 404, including smear-positive/negative, culture-positive (SPCP/SNCP) and HIV+ve/−ve) were measured by enzyme-linked immunoassay and statistically analysed. In multinomial logistic regression, expectoration, chest pain, wasting, and culture count positively associated with CRP (p < 0.001), while smear count positively associated with anti-A60 IgG (p = 0.090). Expectoration and enlarged lymph nodes negatively associated with anti-A60 IgA (p = 0.018). Biomarker distribution and diagnostic potential varied significantly by symptoms and bacilli burden, and across different PTB subpopulations. CRP was correlated poorly with anti-A60 antibodies, while anti-A60 IgA and IgG were correlated in non-tuberculosis (TB) and SPCP patients (p < 0.001). When combined, anti-A60 IgG and CRP best discriminated SPCP/HIV−ve from non-TB (AUC: 0.838, 95% CI: 0.783–0.894), while anti-A60 IgA and CRP performed best in discriminating HIV+ve PTB from non-TB (AUC: 0.687, 95% CI: 0.598–0.777). Combined CRP and anti-A60 antibodies had significantly reduced accuracy in SNCP and SNCP/HIV+ve compared to SPCP/HIV−ve subpopulations. The complex relationships between host factors and biomarkers suggest their limited utility, especially in SNCP/HIV+ve subpopulations, highlighting the importance of examining host response and immune biomarkers across relevant patient subpopulations.

Exploring the best possible route of infection of Verotxin producing Escherichia coli in development of experimental gastroenteritis among streptomycin treated murine model

The prevalence of Escherichia coli O157:H7 induced bacteremia generate a critical problem in modern medical therapy for bacterial infections. This study sought to find out the best possible route and dose of E. coli 0157:H7 infection in experimental murine model by periodic stool and blood culture count of relevant bacterial strains. Streptomycin treated mouse model were used for investigating the clinical manifestation exerted by stx1A and stx2A positive E. coli O157:H7 with increasing doses applied through three alternative routes (oral, intramuscular and intraperitoneal). The highest titer of orally added E. coli 0157:H7 among five test doses started showing symptoms at the earliest time and reached moribund condition about 48 hours just before being dead. The oral way of E.coli O157:H7 at the dose of 100 ml suspension containing 1 ´ 109CFU ml-1 was taken as the most potent concentration in producing bacterial fatality and hence was selected as the minimum lethal dose (MLD).Journal of Bangladesh Academy of Sciences, Vol. 39, No. 1, 53-58, 2015

Does culture count? Comparative performances of top family and non-family firms

Sixty-five of the world’s largest family firms were compared against with those of a matched sample of 65 non-family firms. Contrary to previous studies, family firms here displayed higher profitability and a broadly positive (if slightly inconsistent) relationship between increasing family ownership levels and performance. Sales growth was also consistently higher over 20 years when averaged worldwide. Since other studies have mainly been restricted to single countries or regions, we further analysed differences across continents and country cultures. Within both North America and Europe family and non-family firms were equally profitable (though family firms grew relatively faster in North America). The same was true for ‘high-trust’ countries and also for Anglo-Saxon regions. However, in low-trust countries and also in more long-termist Asian countries, family firms performed better than non-family firms both in terms of profitability and sales growth.

Mice tuberculosis quantified by the lung density technique

Groups of CF1 mice were respectively infected intravenously with four decreasing doses of the virulent H37Rv strain of Mycobacterium tuberculosis var. hominis and the progress of tuberculous disease was followed by three techniques yielding essentially objective results. Survival rates showed that 84% of the mice infected with the largest dose died within 30 days of infection but this technique was unable to differentiate among the other three groups of mice infected with smaller doses. Bacterial culture counts performed after increasing intervals of infection on spleen homogenates of similarly infected groups of mice showed that different degrees of tuberculous involvement had effectively been induced in the four groups. Lung density determinations performed on the same groups of animals gave results establishing that this technique was capable of distinguishing the four groups of mice one from another. The observation that the lung density technique reflects the degree of tuberculous disease accurately was further substantiated by experiments performed on groups of mice respectively injected intravenously with comparable numbers of viable cells of seven mycobacterial strains of different virulence, all harvested at the same "physiological age." Statistically significant differences existed between the experimental groups infected with the virulent strains on the one hand and those injected with the avirulent ones on the other; no differences existed among the groups infected with virulent strains or among those injected with avirulent ones. Of particular interest is the observation that the lung density technique can also differentiate groups of mice injected either with virulent or avirulent strains from those injected with the attenuated bovine BCG strain. The results of both the bacterial culture count and lung density techniques applied to the same groups of mice in the early and late phases of tuberculous disease are discussed.

EXPERIMENTS ON THE METHANE BACTERIA IN SLUDGE

An agar culture method for determining the numbers of methanogenic bacteria in sludge was developed. Hydrogen and carbon dioxide were provided as substrate and palladium as a reduction catalyst. Sodium sulphide could also be used for reducing the medium. A methanogenic organism could be identified by correlating methane production with presence of a particular type of colony which was the most abundant. Fifteen strains which were pure cultured were all similar and were classified as Methanobacterium formicicum. The culture count for methane bacteria in sludge ranged between 105 and 108 per ml. The rate of fermentation and the efficiency of conversion of substrate into cell material were studied. Presence of an acetate-fermenting methanogenic organism was established but no pure cultures could be obtained. Methanobacterium formicicum appeared to be the only methane producer growing in the dilution series used for counts.