Biomedical subjects

Anupam Das

Publications and source records attributed to Anupam Das.

4 recordsLinked to original sources

PubMed2026

Complete Genome Sequencing of Occult Hepatitis B Virus in Hemodialysis Patients Reveals Subgenotype D2 and Immune Escape Mutations in Bangladesh.

Hepatitis B virus (HBV) remains a major global health concern, and occult HBV infection (OBI) presents significant diagnostic and clinical challenges, particularly among hemodialysis (HD) patients. This study is aimed at characterizing complete HBV genomes from maintenance HD patients with OBI in Bangladesh to elucidate genetic features, mutational patterns, and clinical implications. Serum samples from two HBsAg-negative HD patients were screened by ELISA and quantitative PCR. Viral DNA was amplified by PCR across four overlapping open reading frames (ORFs) and sequenced on the Illumina platform. Genome assembly, phylogenetic analysis, and mutational profiling were performed using reference datasets and bioinformatics tools. Antigenicity and hydrophilicity of HBsAg were predicted in silico. Both patients were anti-HBc and anti-HBs positive with high HBV DNA loads (2.29 × 1010 and 2.53 × 1010 copies/mL). Full-length genomes (3182 bp) were successfully sequenced and phylogenetic analysis showed both HBV genomes clustered within Genotype D, Subgenotype D2, and subtype ayw3, consistent with previously reported Bangladeshi HBV genomes. Comparative mutational analysis identified substitutions such as T1753C in the basal core promoter, C1845T in preC, and D144E within the "a" determinant of HBsAg, suggesting potential roles in vaccine escape, immune escape, and diagnostic failure. Several nonsynonymous mutations were also detected in polymerase, though none were potentially associated with antiviral resistance. Antigenicity and hydrophilicity profiles of HBsAg and its major hydrophilic region remained largely conserved. These findings demonstrate the persistence of OBI in HD patients and provide an initial indication of the need for genomic surveillance to monitor immune-escape mutations and improve HBV diagnostic strategies in endemic regions.

HBV genome sequencing↗

PubMed2006

Rare serotype non-typhoidal Salmonella sepsis.

An 11-month female with a poor socio-economic status presented to a tertiary care paediatric hospital with complaints of fever of 4-5 days and diarrhoea of 20 days duration. The patient didn't respond to the prescribed antimicrobials namely--Norfloxacin and metronidazole. On admission she was diagnosed as persistent diarrhea with PEM grade III with sepsis. Stool examination and culture were negative for any pathogens, however blood culture yielded growth of Salmonella Virchow which was susceptible to most common antimicrobial agents excepting Trimethoprim Sulfamethoxazole. Salmonella Virchow is a common non-typhoidal Salmonellae causing bacteremia in the west, however this is the first report of bacteremia by S. virchow from India.

Bacteremia↗

PubMed2005

Refractory isosporiasis.

The authors describe a case of severe debilitating diarrhea due to isosporiasis in a two year old child, a known case of systemic vasculitis receiving prolonged corticosteroids therapy, an association rarely reported previously. It was refractory to treatment with dihydrofolate reductase inhibitor combined with sulfonamide such as cotrimoxazole to which isosporiasis usually responds well and is being described here for clinical interest and uniqueness of its presentation and laboratory findings.

Animals↗

PubMedDate not supplied

Plasmodium lactate dehydrogenase assay to detect malarial parasites.

BACKGROUND: Microscopic examination of blood smears remains the gold standard for the diagnosis of malaria. However, it is labour-intensive and requires skilled operators. Immunochromatographic dipstick assays provide a potential alternative. One such dipstick, the Plasmodium lactate dehydrogenase assay (pLDH), is based on detection of the Plasmodium intracellular metabolic enzyme, LDH. The differentiation of malarial parasites is based on the antigenic differences between the pLDH isoforms. This study was designed to assess the sensitivity and specificity of pLDH assays in detecting and differentiating between various malarial species compared with microscopy. METHODS: Blood samples (n = 124) submitted to our laboratory for routine diagnosis of malaria were included in this study. From each blood sample, two thin films and a quantitative buffy coat (QBC) were made for microscopy. Thin films were stained with Giemsa and acridine orange. The pLDH assay was performed on all the samples according to the manufacturer's instructions. RESULTS: Of the 124 blood samples, 84 were negative by all methods (Giemsa, acridine orange, QBC and pLDH assay). Of the 38 samples positive for Plasmodium falciparum on microscopy, pLDH assay correctly identified 36 at parasite counts as low as < 40 parasites/microl and had a sensitivity and specificity of 94.3% and 97.6%, respectively. Of the 21 samples positive for Plasmodium vivax, pLDH assay correctly identified 19 at parasite counts as low as < 80/microl, and had a sensitivity and specificity of 90.4% and 100%, respectively. However, it failed to identify two Plasmodium vivax infections at parasite counts of 5000/microl and > 200/microl, suggesting that plasmodial gene deletions could be responsible for non-expression of pLDH. CONCLUSIONS: Our data demonstrate that pLDH assay, given its accuracy, rapidity (10-15 minutes), ease of performance and interpretation, can be a useful tool for the detection of malaria in countries where both plasmodial species are co-endemic and where laboratory support is limited.

Animals↗