Prasanna Samuel

Associations of variants in FTO and Near MC4R with obesity traits in South Asian Indians

Recent genome‐wide association studies show that loci in FTO and melanocortin 4 receptor (MC4R) associate with obesity‐related traits. Outside Western populations the associations between these variants have not always been consistent and in Indians it has been suggested that FTO relates to diabetes without an obvious intermediary obesity phenotype. We investigated the association between genetic variants in FTO (rs9939609) and near MC4R (rs17782313) with obesity‐ and type 2 diabetes (T2DM)‐related traits in a longitudinal birth cohort of 2,151 healthy individuals from the Vellore birth cohort in South India. The FTO locus displayed significant associations with several conventional obesity‐related anthropometric traits. The per allele increase is about 1% for BMI, waist circumference (WC), hip circumference (HC), and waist—hip ratio. Consistent associations were observed for adipose tissue‐specific measurements such as skinfold thickness reinforcing the association with obesity‐related traits. Obesity associations for the MC4R locus were weak or nonsignificant but a signal for height (P < 0.001) was observed. The effect on obesity‐related traits for FTO was seen in adulthood, but not at younger ages. The loci also showed nominal associations with increased blood glucose but these associations were lost on BMI adjustment. The effect of FTO on obesity‐related traits was driven by an urban environmental influence. We conclude that rs9939609 variant in the FTO locus is associated with measures of adiposity and metabolic consequences in South Indians with an enhanced effect associated with urban living. The detection of these associations in Indians is challenging because conventional anthropometric obesity measures work poorly in the Indian “thin‐fat” phenotype.

Rotavirus antigenemia in Indian children with rotavirus gastroenteritis and asymptomatic infections

BACKGROUND Rotavirus gastroenteritis results in significant morbidity and mortality in Indian children. Although there are numerous studies on rotavirus diarrhea, there are few reports on antigenemia and extraintestinal presentations in these populations. METHODS Following screening for rotavirus antigen of stool samples from children with and without acute gastroenteritis with a commercial enzyme immunoassay (EIA), a total of 199 stool and serum sample pairs were identified for additional testing. All EIA-positive stool samples were genotyped, and viral load estimated by real-time reverse-transcriptase polymerase chain reaction (RT-PCR). Serum samples were tested for rotavirus antigen by an in-house EIA, and antigen was quantified by optical density. Scoring of disease severity was performed for all hospitalized children. Data on extra-intestinal presentations were collected if available. RESULTS Based on screening of stool samples by EIA, the study population could be divided into 3 groups, including 111 children with rotavirus diarrhea, 44 children with diarrhea and no rotavirus detected in stool specimens, and 44 children with asymptomatic rotavirus infection. Antigenemia was significantly higher among children with rotavirus diarrhea (50.4%) than among children with non-rotaviral diarrhea (16%) or asymptomatic infections (2.3%) (P < .001). Low copies of rotavirus were detected by RT-PCR in all 7 children with EIA-negative stool specimens and antigenemia. Presence and levels of rotavirus antigen in serum specimens correlated with stool viral load. Children with antigenemia had significantly more-severe disease but not more extraintestinal presentations than did children without antigenemia. CONCLUSIONS Antigenemia occurs frequently in rotavirus infection and correlates with virus replication in the gut but not with extra-intestinal presentations.

Mapping the compound muscle action potentials of cricothyroid muscle using electromyography in thyroid operations: a novel method to clinically type the external branch of the superior laryngeal nerve.

Objective:Variations of the external branch of the superior laryngeal nerve (EBSLN) are well represented in literature but with conflicting reports about the types and variations. Using EMG, the cricothyroid compound muscle action potential (CMAP) was recorded, to identify the EBSLN and classified them according to clinical variation during routine thyroid operations. Summary Background Data:There is increasing awareness among patients and physicians of the consequences of injury to the external laryngeal nerve in thyroid surgeries. There are at least 4 types, which are described in the literature.1 The gold standard of nerve identification is EMG, which we used during operations in this study to identify all the EBSLN by demonstrating CMAP and reclassify them. Based on this principle, to avoid injury during thyroidectomy, we propose a new classification. Methods:This study was a prospective, descriptive study of the EBSLN done during elective thyroidectomy operations. CMAP was demonstrated and EMG was plotted to identify and type them according to clinical variations. The distance between the entry of superior thyroid vessels (STVs) to the lobe and the EBSLN, relationship with the cricothyroid muscle and inferior constrictor muscle were taken into consideration. Based on the possible risk to this during thyroidectomy, we divided them into 4 types. Results:A total of 70 external laryngeal nerves were dissected and confirmed by the CMAPs in 35 total thyroidectomy patients. Using CMAPs, all the nerves were identified. Ia.The nerve can be found within 1 cm from the entry of the vessels into the gland either anterior or intertwined to the STVs or within 3 cm from the cricoid cartilage. Ib.The nerve can be found posterior to the vessels but within 1 cm from the entry of the STV into the gland. This entry point was close to the anterior insertion line of the CT muscle onto cricoid cartilage. II.Nerve can be found within 1 to 3 cm from the entry of the vessels into the gland or within 3 to 5 cm from the cricoid cartilage. III.Nerve can be found between 3 and 5 cm from the entry of the vessels into the gland or more than 5 cm from the cricoid cartilage. Conclusion:New clinical typing of the EBSLN will give a better understanding of the EBSLN in the intraoperative period. EBSLN need not be identified in routine thyroidectomy operations. Even in large goiters, the incidence of nerve at risk does not increase significantly. Injury to EBSLN can be avoided if the principle of ligating the STVs individually away from the CT muscle and close to the capsule of the gland is followed.

Antiviral Resistance Mutations and Genotype-Associated Amino Acid Substitutions in Treatment-Naïve Hepatitis B Virus-Infected Individuals from the Indian Subcontinent

Background/Aims: Antiviral resistance is a major challenge to the treatment currently available for hepatitis B virus (HBV). In this study, mutations that may affect the antiviral efficacy in treatment-naïve HBV-infected individuals were analyzed. Methods: Ninety-seven treatment-naïve HBV-infected individuals were included in this study. HBV reverse transcriptase (rt) domains were sequenced and nucleotide differences were compared to GenBank wild-type sequences. Furthermore, HBV genotypes, subgenotypes and subtypes were determined by analyzing surface gene sequences. Results: An adefovir-related rtI233V mutation was identified in 4 subjects. The rtS213T lamivudine and entecavir refractory mutant was presented in 3 individuals. Altogether, drug-related, atypical and novel HBVrt amino acid substitutions were seen in 73 positions. The HBV genotypes A, C, D and G were depicted in 15, 21, 60 and 1 individuals, respectively. There were 17 HBVrt amino acid substitutions that are associated with certain genotypes of HBV. Mutations in HBVrt corresponded to established surface gene mutations in 9 patients. Conclusion: This data shows that antiviral-resistant HBV strains do exist in treatment-naïve individuals in this region. Further studies are essential to characterize the role of HBVrt amino acid substitutions in response to anti-HBV therapy.

Performance Characteristics and Comparison of Abbott and artus Real-Time Systems for Hepatitis B Virus DNA Quantification

ABSTRACT Virological monitoring of hepatitis B virus (HBV) DNA is critical to the management of HBV infection. With several HBV DNA quantification assays available, it is important to use the most efficient testing system for virological monitoring. In this study, we evaluated the performance characteristics and comparability of three HBV DNA quantification systems: Abbott HBV real-time PCR (Abbott PCR), artus HBV real-time PCR with QIAamp DNA blood kit purification (artus-DB), and artus HBV real-time PCR with the QIAamp DSP virus kit purification (artus-DSP). The lower limits of detection of these systems were established against the WHO international standards for HBV DNA and were found to be 1.43, 82, and 9 IU/ml, respectively. The intra-assay and interassay coefficients of variation of plasma samples (1 to 6 log10 IU/ml) ranged between 0.05 to 8.34% and 0.16 to 3.48% for the Abbott PCR, 1.53 to 26.85% and 0.50 to 12.89% for artus-DB, and 0.29 to 7.42% and 0.94 to 3.01% for artus-DSP, respectively. Ninety HBV clinical samples were used for comparison of assays, and paired quantitative results showed strong correlation by linear regression analysis (artus-DB with Abbott PCR, r = 0.95; Abbott PCR with artus-DSP, r = 0.97; and artus-DSP with artus-DB, r = 0.94). Bland-Altman analysis showed a good level of agreement for Abbott PCR and artus-DSP, with a mean difference of 0.10 log10 IU/ml and limits of agreement of −0.91 to 1.11 log10 IU/ml. No genotype-specific bias was seen in all three systems for HBV genotypes A, C, and D, which are predominant in this region. This finding illustrates that the Abbott real-time HBV and artus-DSP systems show more comparable performance than the artus-DB system, meeting the current guidelines for assays to be used in the management of hepatitis B.

Association of HLA and TNF polymorphisms with the outcome of HBV infection in the South Indian population

The role of host genetic factors in the pathogenesis and outcome of hepatitis B virus (HBV) infection is not well known. We assessed the association of HLA and TNF (rs361525, rs1800629, rs1799724, rs1800630 and rs1799964) polymorphisms with HBV outcome in the South Indian population. Association of HLA polymorphism was analyzed in 90 individuals from each group, that is, spontaneous recovery (SR) and chronic-HBV (C-HBV) infection. The role of TNF polymorphisms was evaluated in 150 subjects with SR and 137 patients with C-HBV infection. After adjusting for age and sex, HLA-DRB1*07:01 was strongly associated with chronicity (corrected P-value (pc) <0.005, odds ratio (OR) 3.76, 95% confidence interval (CI) 1.84–7.68). The rs1800630 genotype was associated with HBV outcome in codominant (pc<0.01, OR=1.99, 95% CI 1.30–3.05) and dominant (pc<0.01, OR=2.28, 95% CI 1.35–3.84) analyzing models after adjusting for age and sex. Similarly, the rs1799964 genotype was associated with HBV outcome in codominant (pc=0.01, OR=1.57, 95% CI 1.09–2.27) and dominant (pc<0.01, OR=2.21, 95% CI 1.27–3.83) analyzing models. Haplotype analysis (rs1799964/rs1800630/rs1799724/rs1800629/rs361525) revealed that the CACGG haplotype was strongly associated with C-HBV infection (P=0.0004). Our study suggests that inheritance of HLA and TNF polymorphisms might explain the outcome of HBV infection in the South Indian population.

Clinical profile and outcome of patients hospitalized with dimethyl and diethyl organophosphate poisoning.

The two major classes of organophosphate compounds, dimethyl and diethyl organophosphates, have different toxicokinetic properties. This study evaluated the clinical profile and outcomes in patients admitted with poisoning with these two classes of organophosphates. Methods. This retrospective study spanned 6 years (2002–2007). Patients were treated with atropine and supportive care including ventilation, as required, and followed up until death or hospital discharge. Oximes were not administered. Of the 422 charts retrieved, 396 fulfilled inclusion criteria. Data on the clinical profile, ventilation, length of hospital stay, incidence of intermediate syndrome and mortality were extracted. Results. The mean (±standard deviation) age was 31.4 ± 12.7 years with a male preponderance (2.6:1). The median (interquartile range (IQR)) admission pseudocholinesterase level of 317 (222–635) U/L indicated significant inhibition of cholinesterase activity. The median lag-time to presentation to our hospital was 5 (IQR 3–8.5) hours. Oximes were administered at a primary center in 33 patients (8.3%). Dimethyl organophosphate was ingested by 141 patients, diethyl organophosphate by 108, S-alkyl organophosphate by 2, and an un-identified organophosphate by 145 patients. Ventilation was required in 260 patients (65.7%); the median duration of ventilation being 7.5 (IQR 3–12) days. Overall mortality was 13.1%. There was a significant difference between dimethyl and diethyl organophosphate compounds in ventilatory requirement (76% vs. 56%, adjusted odds ratio (OR) 2.37, 95% CI 1.01–5.57, p = 0.047), duration of ventilation (11 (4–15) vs. 5 (2–9) days, adjusted OR 1.12, 95%CI 1.04–1.21, p = 0.002) and incidence of intermediate syndrome (72/125 (58%) vs. 24/92 (26%), adjusted OR 2.84, 95%CI 1.38–5.86, p = 0.004). Mortality was similar in the two groups (20/141 (14%) vs. 7/108 (6%), dimethyl vs. diethyl organophosphate, adjusted OR 1.29, 95%CI 0.43–3.94, p = 0.65). Conclusions. Patients admitted with dimethyl organophosphate poisoning have a worse outcome compared with diethyl organophosphate poisoning for clinically relevant patient outcomes.

Risk factors for tuberculosis among health care workers in South India: a nested case-control study.

OBJECTIVE The epidemiology of tuberculosis (TB) among health care workers (HCWs) in India remains under-researched. This study is a nested case-control design assessing the risk factors for acquiring TB among HCWs in India. STUDY DESIGN AND SETTINGS It is a nested case-control study conducted at a tertiary teaching hospital in India. Cases (n = 101) were HCWs with active TB. Controls (n = 101) were HCWs who did not have TB, randomly selected from the 6,003 subjects employed at the facility. Cases and controls were compared with respect to clinical and demographic variables. RESULTS The cases and controls were of similar age. Logistic regression analysis showed that body mass index (BMI) <19 kg/m(2) (odds ratio [OR]: 2.96, 95% confidence interval [CI]: 1.49-5.87), having frequent contact with patients (OR: 2.83, 95% CI: 1.47-5.45) and being employed in medical wards (OR: 12.37, 95% CI: 1.38-110.17) or microbiology laboratories (OR: 5.65, 95% CI: 1.74-18.36) were independently associated with increased risk of acquiring TB. CONCLUSION HCWs with frequent patient contact and those with BMI <19 kg/m(2) were at high risk of acquiring active TB. Nosocomial transmission of TB was pronounced in locations, such as medical wards and microbiology laboratories. Surveillance of high-risk HCWs and appropriate infrastructure modifications may be important to prevent interpersonal TB transmission in health care facilities.

Absence of birth-weight lowering effect of ADCY5 and near CCNL, but association of impaired glucose-insulin homeostasis with ADCY5 in Asian Indians.

Background A feature of the Asian Indian phenotype is low birth weight with increased adult type 2 diabetes risk. Most populations show consistent associations between low birth weight and adult type 2 diabetes. Recently, two birth weight-lowering loci on chromosome 3 (near CCNL1 and ADCY5) were identified in a genome-wide association study, the latter of which is also a type 2 diabetes locus. We therefore tested the impact of these genetic variants on birth weight and adult glucose/insulin homeostasis in a large Indian birth cohort. Methodology/Principal Findings Adults (n = 2,151) enrolled in a birth cohort (established 1969-73) were genotyped for rs900400 (near CCNL1) and rs9883204 (ADCY5). Associations were tested for birth weight, anthropometry from infancy to adulthood, and type 2 diabetes related glycemic traits. The average birth weight in this population was 2.79±0.47 kg and was not associated with genetic variation in CCNL1 (p = 0.87) or ADCY5 (p = 0.54). Allele frequencies for the ‘birth weight-lowering’ variants were similar compared with Western populations. There were no significant associations with growth or adult weight. However, the ‘birth weight-lowering’ variant of ADCY5 was associated with modest increase in fasting glucose (β 0.041, p = 0.027), 2-hours glucose (β 0.127, p = 0.019), and reduced insulinogenic index (β -0.106, p = 0.050) and 2-hour insulin (β -0.058, p = 0.010). Conclusions The low birth weight in Asian Indians is not even partly explained by genetic variants near CCNL1 and ADCY5 which implies that non-genetic factors may predominate. However, the ‘birth-weight-lowering’ variant of ADCY5 was associated with elevated glucose and decreased insulin response in early adulthood which argues for a common genetic cause of low birth weight and risk of type 2 diabetes.

Norovirus Gastroenteritis in a Birth Cohort in Southern India

Background Noroviruses are an important cause of gastroenteritis but little is known about disease and re-infection rates in community settings in Asia. Methods Disease, re-infection rates, strain prevalence and genetic susceptibility to noroviruses were investigated in a birth cohort of 373 Indian children followed up for three years. Stool samples from 1856 diarrheal episodes and 147 vomiting only episodes were screened for norovirus by RT-PCR. Norovirus positivity was correlated with clinical data, secretor status and ABO blood group. Results Of 1856 diarrheal episodes, 207 (11.2%) were associated with norovirus, of which 49(2.6%) were norovirus GI, 150(8.1%) norovirus GII, and 8 (0.4%) were mixed infections with both norovirus GI and GII. Of the 147 vomiting only episodes, 30 (20.4%) were positive for norovirus in stool, of which 7 (4.8%) were norovirus GI and 23 (15.6%) GII. At least a third of the children developed norovirus associated diarrhea, with the first episode at a median age of 5 and 8 months for norovirus GI and GII, respectively. Norovirus GI.3 and GII.4 were the predominant genotypes (40.3% and 53.0%) with strain diversity and change in the predominant sub-cluster over time observed among GII viruses. A second episode of norovirus gastroenteritis was documented in 44/174 (25.3%) ever-infected children. Children with the G428A homozygous mutation for inactivation of the FUT2 enzyme (se428se428) were at a significantly lower risk (48/190) of infection with norovirus (p = 0.01). Conclusions This is the first report of norovirus documenting disease, re-infection and genetic susceptibility in an Asian birth cohort. The high incidence and apparent lack of genogroupII specific immunity indicate the need for careful studies on further characterization of strains, asymptomatic infection and shedding and immune response to further our understanding of norovirus infection and disease.