Non-covalent bonding interaction of surfactants with functionalized carbon nanotubes in proton exchange membranes for fuel cell applications.

Dispersion of functionalized multiwalled carbon nanotubes (MWCNTs) in proton exchange membranes (PEMs) was conducted via non-covalent bonding between benzene rings of various surfactants and functionalized MWCNTs. In the solution casting method, dispersion of functionalized MWCNTs in PEMs such as Nafion membranes is a critical issue. In this study, 1 wt.% pristine MWCNTs (p-MWCNTs) and oxidized MWCNTs (ox-MWCNTs) were reinforced in Nafion membranes by adding 0.1-0.5 wt.% of a surfactant such as benzalkonium chloride (BKC) as a cationic surfactant with a benzene ring, Tween-80 as a nonanionic surfactant without a benzene ring, sodium dodecylsulfonate (SDS) as an anionic surfactant without a benzene ring, or sodium dodecylben-zenesulfonate (SDBS) as an anionic surfactant with a benzene ring and their effects on the dispersion of nanocomposites were then observed. Among these surfactants, those with benzene rings such as BKC and SDBS produced enhanced dispersion via non-covalent bonding interaction between CNTs and surfactants. Specifically, the surfactants were adsorbed onto the surface of functionalized MWCNTs, where they prevented re-aggregation of MWCNTs in the nanocomposites. Furthermore, the prepared CNTs reinforced nanocomposite membranes showed reduced methanol uptake values while the ion exchange capacity values were maintained. The enhanced properties, including thermal property of the CNTs reinforced PEMs with surfactants, could be applicable to fuel cell applications.

Incidence of young onset insulin-requiring diabetes mellitus among 18- to 30-year-olds in Dhaka, Bangladesh (1994-2003).

Little information is available regarding the epidemiology of young onset insulin-requiring diabetes mellitus (IRDM). We described the incidence of young onset IRDM and its trend in males and females of Dhaka, Bangladesh. Subsequently, factors related to possible sex difference were investigated. Young onset IRDM was defined as diabetic patients aged 18-30 years who required three months or more insulin treatment but presented no ketonuria. Between 1994 to 2003, 1804 cases were registered. Incidence rates were calculated with denominators based on the population census 2001. The overall annual incidence of young onset IRDM for the period 1994-2003 was 8.5 per 100,000 persons (95% CI: 7.2-7.9), and the corresponding value for females (10.9 per 100,000 persons, 95% CI: 9.2-12.1) was higher than that in males (6.7 per 100,000 persons, 95% CI 5.6-7.9). The incidence rate significantly increased in females during the investigated period, but not in males (p for sex interaction < 0.01). There was a significantly higher increment of female cases with a body mass index > or = 25.0 kg/m2 (overweight/obesity) (19 percentage point) compared to that of males (3 percentage point) between 1994-1998 and 1999-2003 (p for sex interaction < 0.01). The incidence of young onset IRDM is increasing in the Dhaka City population among females, which is attributed to the increase in overweight/obese female cases.

Microbiome Profiling of Enterotoxigenic Escherichia coli (ETEC) Carriers Highlights Signature Differences between Symptomatic and Asymptomatic Individuals.

Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea in children in low- and middle-income countries (LMICs). However, large-scale pathogen burden studies in children have identified ETEC in the guts of both symptomatic patients and controls. The factors that influence this balance are poorly understood, but it is postulated that the gut microbiome may play a role in either resistance or progression to disease. In this study, we profiled the microbiomes of children and adults from Bangladesh who were asymptomatically or symptomatically infected with ETEC. Symptomatic patients had significantly higher numbers of sequenced reads mapping to both E. coli and two ETEC toxins, suggesting higher bacterial burden. They were also significantly more likely to be coinfected with enteroaggregative E. coli (EAEC) and had higher proportions of other Gammaproteobacteria, including Klebsiella, Salmonella, and Haemophilus. Colonization with ETEC was also associated with increased prevalence of antimicrobial resistance (AMR) genes, most notably those of the ß-lactamase class. Taxonomic profiles were distinctly different between all groups in both species richness and composition, although the direction of these changes was different in adults and children. As seen previously, children with high E. coli burdens also had higher proportions of Streptococcus spp., while healthy children were more heavily colonized by Bifidobacterium spp. Our study provides insight into the microbiome changes that occur upon infection with ETEC in an endemic setting and provides rationale for future studies investigating how the microbiome may protect or predispose individuals to symptomatic infections with gastrointestinal pathogens. IMPORTANCE Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea in children in low- and middle-income countries. However, these bacteria are often identified in both patients and healthy controls. We do not yet understand why only some people get sick, but it has been suggested that the gut microbiome might play a role. In this study, we used metagenomic sequencing to profile the gut microbiomes of individuals in Bangladesh, with or without a symptomatic ETEC infection. In general, individuals with high levels of ETEC also harbored other pathogenic E. coli strains, higher proportions of Gammaproteobacteria such as Salmonella and Klebsiella, and a higher burden of antimicrobial resistance genes in their guts. Healthy children, in contrast, had higher levels of bifidobacteria. These data confirm that the composition of the gut microbiome is different between symptomatic and asymptomatic people and provides important preliminary information on the impact of the gut microbiome in intestinal infections.

Rising prevalence of type 2 diabetes in rural Bangladesh: a population based study.

The aim of the study was to determine the temporal changes in the prevalence of type 2 diabetes mellitus and its associated risk factors in a rural population of Bangladesh. A total of 4757 subjects age >/=20 years both male and female were enrolled randomly in a cross-sectional study in 1999. The same area and population was reinvestigated in 2004 following the same selection procedure, on a sample of 3981 individuals. Structural and economical changes were noted for the last 5 years in the locality. An increased prevalence of diabetes was found with 6.8% in the present survey compared with 2.3% in the earlier survey (p<0.05). Age, BMI and systolic blood pressure were found to be significant risk factors following both for FBG and for OGTT. WHR was found to be a significant risk factor for men only. A substantial agreement was observed between FBG and OGTT (kappa 0.63) compared to the previous investigation in 1999 (kappa 0.40). Differences in the indices of obesity, that is BMI, WHR and waist girth, may in part explain the increased prevalence, which in turn may explain due to fast-expanded urbanization. The state of affairs warrants immediate measures necessary to prevent the epidemic particularly in the localities that are in the transition phase from rural to semi-urban facilities.

Development of a Simple, Peripheral-Blood-Based Lateral-Flow Dipstick Assay for Accurate Detection of Patients with Enteric Fever.

Enteric fever is a systemic infection caused by typhoidal strains of Salmonella enterica and is a significant cause of mortality and morbidity in many parts of the world, especially in resource-limited areas. Unfortunately, currently available diagnostic tests for enteric fever lack sensitivity and/or specificity. No true clinically practical gold standard for diagnosing patients with enteric fever exists. Unfortunately, microbiologic culturing of blood is only 30 to 70% sensitive although 100% specific. Here, we report the development of a lateral-flow immunochromatographic dipstick assay based on the detection of Salmonella enterica serovar Typhi (S Typhi) lipopolysaccharide (LPS)-specific IgG in lymphocyte culture secretion. We tested the assay using samples from 142 clinically suspected enteric fever patients, 28 healthy individuals residing in a zone where enteric fever is endemic, and 35 patients with other febrile illnesses. In our analysis, the dipstick detected all blood culture-confirmed S Typhi cases (48/48) and 5 of 6 Salmonella enterica serovar Paratyphi A blood cultured-confirmed cases. The test was negative in all 35 individuals febrile with other illnesses and all 28 healthy controls from the zone of endemicity. The test was positive in 19 of 88 individuals with suspected enteric fever but with negative blood cultures. Thus, the dipstick had a sensitivity of 98% compared to blood culture results and a specificity that ranged from 78 to 100% (95% confidence interval [CI], 70 to 100%), depending on the definition of a true negative. These results suggest that this dipstick assay can be very useful for the detection of enteric fever patients especially in regions of endemicity.

Diabetes and impaired fasting glycemia in a rural population of Bangladesh.

OBJECTIVE: To determine the prevalence of type 2 diabetes and impaired fasting glycemia (IFG) in a rural population of Bangladesh. RESEARCH DESIGN AND METHODS: A cluster sampling of 4,923 subjects >/=20 years old in a rural community were investigated. Fasting plasma glucose, blood pressure, height, weight, and girth of waist and hip were measured. BMI and waist-to-hip ratio (WHR) were calculated. Total cholesterol, triglycerides, and HDL cholesterol were also estimated. We used the 1997 American Diabetes Association diagnostic criteria. RESULTS: The crude prevalence of type 2 diabetes was 4.3% and IFG was 12.4%. The age-standardized prevalence of type 2 diabetes (95% CI) was 3.8% (3.12-4.49) and IFG was 13.0% (11.76-14.16). The subjects with higher family income had significantly higher prevalence of type 2 diabetes (5.9 vs. 3.5%, P < 0.001) and IFG (15.6 vs. 10.8%, P < 0.001) than those with lower income. Employing logistic regression in different models, we found that wealthy class, family history of diabetes, reduced physical exercise, and increased age, BMI, and WHR were the important predictors of diabetes. Total cholesterol, triglycerides, and HDL cholesterol showed no association with diabetes and IFG. CONCLUSIONS: The prevalence of diabetes and IFG in the rural population was found to be on the increase compared with the previous reports of Bangladesh and other Asian studies. Older age, higher obesity, higher income, family history of diabetes, and reduced physical activity were proved significant risk factors for diabetes and IFG, whereas plasma lipids showed no association with diabetes and IFG. Further study may address whether diabetes is causally associated with insulin deficiency or insulin resistance.

Immunoproteomic analysis of antibody in lymphocyte supernatant in patients with typhoid fever in Bangladesh.

We have previously shown that an assay based on detection of anti-Salmonella enterica serotype Typhi antibodies in supernatant of lymphocytes harvested from patients presenting with typhoid fever (antibody in lymphocyte supernatant [ALS] assay) can identify 100% of patients with blood culture-confirmed typhoid fever in Bangladesh. In order to define immunodominant proteins within the S. Typhi membrane preparation used as antigen in these prior studies and to identify potential biomarkers unique to S. Typhi bacteremic patients, we probed microarrays containing 2,724 S. Typhi proteins with ALS collected at the time of clinical presentation from 10 Bangladeshis with acute typhoid fever. We identified 62 immunoreactive antigens when evaluating both the IgG and IgA responses. Immune responses to 10 of these antigens discriminated between individuals with acute typhoid infection and healthy control individuals from areas where typhoid infection is endemic, as well as Bangladeshi patients presenting with fever who were subsequently confirmed to have a nontyphoid illness. Using an ALS enzyme-linked immunosorbent assay (ELISA) format and purified antigen, we then confirmed that immune responses against the antigen with the highest immunoreactivity (hemolysin E [HlyE]) correctly identified individuals with acute typhoid or paratyphoid fever in Dhaka, Bangladesh. These observations suggest that purified antigens could be used with ALS and corresponding acute-phase activated B lymphocytes in diagnostic platforms to identify acutely infected patients, even in areas where enteric fever is endemic.

Identification of in vivo-induced bacterial proteins during human infection with Salmonella enterica serotype Paratyphi A.

Salmonella enterica serotype Paratyphi A is a human-restricted pathogen and the cause of paratyphoid A fever. Using a high-throughput immunoscreening technique, in vivo-induced antigen technology (IVIAT), we identified 20 immunogenic bacterial proteins expressed in humans who were bacteremic with S. Paratyphi A but not those expressed in S. Paratyphi A grown under standard laboratory conditions. The majority of these proteins have known or potential roles in the pathogenesis of S. enterica. These include proteins implicated in cell adhesion, fimbrial structure, adaptation to atypical conditions, oxidoreductase activity, proteolysis, antimicrobial resistance, and ion transport. Of particular interest among these in vivo-expressed proteins were S. Paratyphi A (SPA)2397, SPA2612, and SPA1604. SPA2397 and SPA2612 are prophage related, and SPA1604 is in Salmonella pathogenicity island 11 (SPI-11). Using real-time quantitative PCR (RT-qPCR), we confirmed increased levels of mRNA expressed by genes identified by IVIAT in a comparison of mRNA levels in organisms in the blood of bacteremic patients to those in in vitro cultures. Comparing convalescent- to acute-phase samples, we also detected a significant increase in the reaction of convalescent-phase antibodies with two proteins identified by IVIAT: SPA2397 and SPA0489. SPA2397 is a phage-related lysozyme, Gp19, and SPA0489 encodes a protein containing NlpC/P60 and cysteine, histidine-dependent amidohydrolase/peptidase (CHAP) domains. In a previous study utilizing a different approach, we found that transcripts for 11 and 7 of the genes identified by IVIAT were detectable in organisms in the blood of humans in Bangladesh who were bacteremic with S. Paratyphi A and Salmonella enterica serovar Typhi, respectively. S. Paratyphi A antigens identified by IVIAT warrant further evaluation for their contributions to pathogenesis and might have diagnostic, therapeutic, or preventive relevance.