Calcutta School of Tropical Medicine
Recent publications
Lateral flow immunoassay is the leading Point of Care test and is becoming increasingly essential for its versatile properties. The attraction of lateral flow assay (LFA) has reached its prime position during recent SARS-CoV-2 pandemic and Ebola, Zika epidemics in third world countries where primary screening of the disease and financial issues are very important. During the last decade traditional methodology of LFA was limited to visual detection and qualitative assessment only. However, recently researchers are focusing on the development and improvement of this tool to enhance its specificity, assessment power (quantitative) to make it an alternative to traditional lab-based technology. Modifying working principle and instrumentation, combination of different modern molecular techniques such as Reverse transcription loop mediated isothermal amplification (RT-LAMP), Clustered regularly inter-spaced short palindromic repeat (CRISPR-Cas), Recombinase amplification polymerase (RPA), also association of image-based software, involvement of nanotechnology, implementation of LFA ruler have established authenticity and ultra-specific detection level. These leading immunochromatographic techniques offer simultaneous detection of different analytes from a single sample unit into one multiplex strip and provide the necessary information. This review is a foremost attempt to encompass recent advances of lateral flow assays in combination with molecular biology techniques along with improvements of assay components for improved diagnostic sensitivity and specificity. Some infectious disease diagnosis by LFA with its reporter and low detection limit have also been mentioned in this review.
Aims Metal complexes have ignited considerable interest in the field of chemotherapy after the serendipitous discovery of cisplatin but the severe toxicity of these platinum-based drugs compelled researchers to search for newer, more effective lesser toxic anticancer drugs. Materials and methods Structural analysis is done by different physicochemical techniques including X-ray single crystallography. Toxicity study has been done in normal Swiss albino mice. MTT assay assessed cell viability. Apoptosis, cell cycle arrest, and cell proliferation were assessed by FACS using Annexin V-PI, PI, and CFSE staining respectively. Western blot quantifies protein expression. While cell migration was studied by wound healing assay. Key findings One-pot synthesis of a novel mononuclear cobalt(III)-Schiff base complex (1) (>99 % purity) and its complete characterization have been done. Cell viability assay showed that 1 (IC50 = 16.81 ± 1.33 μM) exhibits cytotoxicity at much lower concentration in comparison to oxaliplatin (IC50 = 31.4 ± 0.69 μM) against MCF-7 cells for 24 h of therapy without being overly toxic to human PBMCs (IC50 ≥ 60 μM). Additional in vitro studies demonstrated that 1 induces apoptosis via G2-M cell cycle arrest and reduces cell proliferation as well as cell migration in MCF-7 cells. In vivo subacute toxicity (28 days) and systemic chronic toxicity (40 days) studies were carried out in normal Swiss albino mice showed 1 is significantly nontoxic to the host. Significance The readily synthesizable, significantly nontoxic cobalt complex with appreciable anticancer activity implies that it might be an effective chemotherapeutic agent for new-age anti-tumor medication.
ABSTRACT The evolution of viral variants and their impact on viral transmission have been an area of considerable importance in this pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We analyzed the viral variants in different phases of the pandemic in West Bengal, a state in India that is important geographically, and compared the variants with other states like Delhi, Maharashtra, and Karnataka, located in other regions of the country. We have identified 57 pango-lineages in 3,198 SARS-CoV-2 genomes, alteration in their distribution, as well as contrasting profiles of amino acid mutational dynamics across different waves in different states. The evolving characteristics of Delta (B.1.617.2) sublineages and alterations in hydrophobicity profiles of the viral proteins caused by these mutations were also studied. Additionally, implications of predictive host miRNA binding/unbinding to emerging spike or nucleocapsid mutations were highlighted. Our results throw considerable light on interesting aspects of the viral genomic variation and provide valuable information for improved understanding of wave-defining mutations in unfolding the pandemic. IMPORTANCE Multiple waves of infection were observed in many states in India during the coronavirus disease 2019 (COVID19) pandemic. Fine-scale evolution of major SARS-CoV-2 lineages and sublineages during four wave-window categories: Pre-Wave 1, Wave 1, Pre-Wave 2, and Wave 2 in four major states of India: Delhi (North), Maharashtra (West), Karnataka (South), and West Bengal (East) was studied using large-scale virus genome sequencing data. Our comprehensive analysis reveals contrasting molecular profiles of the wave-defining mutations and their implications in host miRNA binding/unbinding of the lineages in the major states of India.
Introduction: Co-infection with different agents such as bacterial, viral, and Rickettsia is being increasingly recognized due to greater availability and utilization of the diagnostic tests among malaria patients. Methods: Consecutive admitted malarial cases were included and were subjected to test for general investigations, bacteria, typhoid, dengue, chikungunya, and rest for specific diagnosis. All patients were followed up till discharge or death and appropriate statistical tests were performed. Results: A total of 152 malaria patients were recruited and 27 (18.8%) had concurrent infections. It included 40.7% dengue only, 18.7% pneumonia, 11.1% urinary tract infection (UTI), 7.4% enteric fever, 3.7% leptospirosis, chikungunya, and tuberculous meningitis each, and 3.7% each of dengue with pneumonia and UTI. The organisms isolated were Streptococcus pneumoniae, Klebsiella pneumoniae, Escherichia coli, Salmonella typhi, and Mycobacterium tuberculosis. The mean duration of fever was 6.33 ± 3.63 days with a range of 3-20 days. Blood culture grew in 2 cases S. typhi and K. pneumonia,e. Dengue co-infections had significantly higher clinical and laboratory features of dengue and complications such as bleeding, jaundice, and cholecystitis, whereas rest concurrent infections had a significantly higher proportion of nausea and vomiting, convulsion, altered sensorium, productive cough, urinary symptoms, shock, acute kidney injury, anemia, and mean neutrophil count. There was significantly higher mortality among malaria-dengue concurrent infection group with 2 (15.4%) than malaria mono-infection group 3 (2.4%). Conclusion: Co-infections with malaria are not uncommon, especially dengue fever and other bacterial infections. The dominant clinical picture is of the superimposed infection. Decision should be clinically guided adjunct with specific diagnostic tests, and timely treatment has favorable outcome.
Kala azar elimination programme in India is mainly depends on vector control measures and primary methods of application of insecticides is indoor residual spray (IRS). For vector control IRS should be carried out at regular intervals of six months. Presently, alphacypermethrin is used for IRS. This study was designed to study the impact of IRS with alphacypermethrin by analysing monthly population density following IRS-treatment. Twenty villages of Habibpur block, Malda district was selected for study which were grouped into study arm where IRS was done and control arm where IRS was not done. This study was conducted during April 2019 to June, 2020. In study villages, IRS was done during August, 2019 (1st cycle) and January 2020 (2nd cycle). Before and after IRS, entomological survey was carried out in cattle shades, human habitation and peri-domestic vegetations using mouth aspirators and light traps. Man hour density, per trap per night collection and % of reduction of sand fly abundance was calculated from survey result. In study arm after 14 days of 1st cycle of IRS, sand fly population reduced at rate of 96.5% which continues upto 3 months (85.34%). About 90% sand fly reduced after 14 days but after 3 months of 2nd cycle IRS density increased by 11.6%. Similar finding was recorded in the both cattle sheds and human habitations. Light trap collection from peri-domestic vegetation in both study and control villages were almost similar throughout the study period. Higher reduction rate of sand fly population following IRS showed that the used insecticide is effective against prevailing vector population of the study areas. The IRS has no effect on peri-domestic population. The presence of sand flies out side human habitation and cattle shades might play an important role in increasing population density following reduced residual activity of insecticide.
Lymphatic filariasis, thought to be a neglected tropical disease (NTD) globally, is caused by microscopic, thread-like nematodes. The present study was conducted to identify the microorganisms in the ulcerative wounds of filarial elephantiasis. A total of 100 samples were collected and studied from the patients attended on Filaria OPD, School of Tropical medicine, Kolkata, India. Staphylococcus aureus (46.67%) was identified as the predominant organism among the different aerobic bacteria present in the ulcer, followed by Pseudomonas aeruginosa, Proteus mirabilis, Klebsiella sp., Enterococcus sp., Escherichia coli and Enterobacter sp.
Universal stress protein A (UspA) is ubiquitously over-expressed in varied species of pathogenic bacteria under stress conditions and helps in cell survival. It is also established as a potential drug target against multidrug-resistant (MDR) uropathogenic Escherichia coli. Till date the mode of action of UspA is unexplored. In this study, in silico approach is undertaken to comprehend UspA function by assimilating its structure-function relationship in ten pathogenic bacteria. This study integrates various computational tools; physicochemical characterization by ProtParam, secondary structure analysis by Psipred, construction of dendrogram by CLAP server, protein-protein interactions (PPIs) using STRING, functional enrichment analysis from protein modules by MCODE in Cytoscape, and 3-D structure prediction by Phyre2. In spite of variances in the amino acid sequences of the ten UspA proteins, their secondary structures, and physiochemical properties are comparable. CLAP tool successfully groups the UspA proteins into two distinct clusters; one that consists of ATP binding domain and another without the ATP binding domain. STRING and MCODE analysis indicated that the former group of UspA proteins is associated with transporter proteins and the latter with cell cycle-related proteins respectively. Discrete structural similarities of UspA proteins in the individual clusters are further verified by their 3D model. Most importantly, results from this study elucidate that although the UspA protein function as a stress responder in different bacterial species, its mode of action at the molecular level is discrete. Additionally, the predicted network of proteins associated with UspA in the different pathogenic bacteria can aid the development of innovative therapies against these pathogens.
Cases of meningoencephalitis with no known etiology remain a major challenge to clinical management of brain infections across the world. In this study, we detected and characterized the whole-genome of primate erythroparvovirus 1 (B19V) in cases of meningoencephalitis in India.
Introduction: Drug promotional literature has been an easy and hand-ready drug information source for the physician, which tends to have a powerful impact on physicians’ prescribing behavior. However compromised and biased information presented through promotional materials should be analyzed critically before translating the same to practice. Such information dissemination, its mode and presentation are critically guided by WHO guidelines of ethical drug promotion. The present study was conducted to critically appraise the DPLs distributed to prescribing physicians in outpatient departments of a tertiary care hospital in lines of WHO guidelines. Materials and Methods: Left behind drug promotional brochures were collected randomly from various outpatient departments and were adjudged based on WHO criteria for ethical medicinal drug promotion. DPLs were also evaluated for various claims and references supporting the claims made. Type of pictures used in promotional material, their contextual relevance were assessed. Results: In our study, 5.29% of all DPLs were found fulfilling almost all the WHO criteria for ethical drug promotion. Safety information was absent in 92.79% cases. Only 42.79% of the DPLs had statements supported by cited references. Promotional brochures made striking use of various types of pictures, covering a major area of the promotional material. Conclusion: A hand-in-hand approach of practitioners, pharmaceutical companies and the regulatory authority may help in ethical drug promotion and rational drug prescribing thereby ensuring safer patient outcomes.
Chikungunya virus (CHIKV) infection and subsequent high patient morbidity is a global threat. The present study aimed to identify the potent antiviral agent against Chikungunya virus, with minimum in vitro cytotoxicity. CHIKV nsP4 3D structure was determined using the I-TASSER server followed by its refinement and pocket determination. Furthermore, high-throughput molecular docking was employed to identify candidate CHIKV nsP4 inhibitors in a library containing 214 compounds. The top ranked compound was evaluated further with various assays, including cytotoxicity, antiviral activity, time of drug addition, viral entry attachment, and microneutralization assays. High-throughput computational screening indicated silibinin to have the best interaction with CHIKV nsP4 protein, immature and mature glycoproteins with highest negative free binding energy, - 5.24 to - 5.86 kcal/mol, and the lowest inhibitory constant, 50.47 to 143.2 µM. Further in vitro analysis demonstrated silibinin could exhibit statistically significant (p < 0.05) dose-dependent anti-CHIKV activity within 12.5-100-µM concentrations with CC50 as 50.90 µM. In total, 50 µM silibinin interfered with both CHIKV attachment (75%) and entry (82%) to Vero cells. Time of addition assay revealed silibinin interfered with late phase of the CHIKV replication cycle. Microneutralization assay revealed that silibinin could inhibit clearing of 50% Vero cell monolayer caused by CHIKV-induced CPE at a minimum dose of 25 µM. These data indicated silibinin to be a promising candidate drug against CHIKV infection.
Introduction The search for a protective antibody titer level to prevent coronavirus disease 2019 (COVID-19) infection, progression, and death is far from over. To date, no specific cut-off values have been established for these protective antibodies or neutralizing antibody (NAb) titers. NAb titers inhibit viral replication. Aim To find out the prevailing NAb titre which might give protection from COVID-19 infection, or complication arising out of it. Material and methods The data of COVID-19 patients with NAb titers who underwent reverse transcription polymerase chain reaction and presented with mild symptoms within 3 days after receiving the results were analyzed. The data were obtained from the clinic’s electronic database. Of the recruited patients, 63 were included in the final analysis. All statistical analyses were performed using SPSS v. 21. Results and discussion A highly significant correlation (negative) existed between circulating NAb titer and duration of fever ( P < 0.001); a positive significant correlation existed between the period from the 1st vaccine dose to the period of infection and the NAb titer level ( P < 0.001). The NAb titer was significantly higher in the group that received both doses ( P = 0.00016). Death and admission due to progression to moderate COVID-19 occurred in the group with a NAb titer of less than 10 U/L. Conclusions The risk of complications and death due to COVID-19 may increase if the protective antibody level remains less than 10 U/L. The sample size used in this study was relatively small; therefore, this finding cannot be generalized. Hence, more robust studies should be performed to determine the appropriate protective NAb titer levels.
Dengue infection can result in simple dengue fever or life threatening severe-dengue. Early identification of severe patients is needed for proper disease management. Dengue infection was screened among 168 symptomatic patients by qRT-PCR, anti-dengue IgM and IgG ELISA. Dengue patients were categorized according to WHO-classification. Viral load and dengue-serotypes were determined by qRT-PCR. Levels of acute-phase-proteins (SAP, SAA2; CRP and ApoA1), endothelial (Ang2, VEGF), coagulation (fibrinogen) markers were determined by sandwich-ELISA/immunoturbidimetry/western-blotting. Hepatic (ALT, AST, ALP) and other blood biochemical parameters were studied by autoanalyzer and haematology cell counter. Statistical analysis and protein-protein-interaction network were performed by GraphPad-Prism and STRINGS database, respectively. Among 87 dengue patients, significantly higher levels of Ang2, VEGF, CRP, SAA2, ApoA1, AST, ALT, AST/ALT ratio and low level of fibrinogen were detected in severe-dengue cases compared to dengue without warning-signs, with seven of them severely altered during febrile-phase. Higher fold-change of Ang2, VEGF and decreased fibrinogen were observed among patients with haemorrhagic-manifestation, clinical-fluid accumulation and thrombocytopenia. Functional network analysis predicted Ang2, VEGF & CRP to be functionally and physically connected and SAA2 & ApoA1 to be functioning together. Correlation analyses also validated this connectivity by strong positive correlation between Ang2, VEGF and CRP. PCA analysis followed by hierarchical clustering heatmap analysis segregated severe-dengue patients from the rest, with VEGF, Ang2, ApoA1, AST and ALT clearly distinguishing severe-dengue group. Thus, serum levels of VEGF, Ang2, ApoA1, AST and ALT might act as potential biomarkers for predicting dengue severity during early stage.
Introduction: Human umbilical cord blood is rich in hematopoietic cells. We aimed to focus on the morphological, biochemical, membrane protein profile and surface protein expression differences of erythrocytes, isolated from cord and adult peripheral blood using techniques such as high-resolution scanning electron microscopy (SEM), gel electrophoresis (SDS-PAGE) and flow cytometry. Methods: Adult peripheral blood was collected from consenting adults, and umbilical cord blood was procured from consenting mothers, post-delivery at Medical College, Kolkata. We emphasized on cord and adult peripheral blood erythrocytes' morphological variations using SEM images and protein expression by flow cytometric analysis. Some conventional biochemical analyses such as osmotic fragility of the cell membrane, haemoglobin co-oxidation study and lipid peroxidation assay were done for supporting evidence along with membrane protein content using gel electrophoresis. Results: Our SEM images indicated clear morphological variations in cord erythrocyte with a higher degree of cellular deformities and difference in membrane texture. Flow cytometric analysis of cord erythrocyte showed a significant difference in CD235a expression than adults. We observed an overexpression of GLUT1 and decreased expression of Band 3 in cord erythrocyte membrane. Our results also showed cord erythrocytes have low osmotic fragility, a slower rate of co-oxidation of cord haemoglobin and a lesser lipid peroxidation level than that of adults. Conclusion: Cord blood erythrocytes have deeper indentations leading to higher flexibility, more oxygen-carrying capacity and less osmotic fragility in comparison with adult erythrocytes. The expression of CD235a and Band 4.5 (GLUT 1) was significantly higher in cord erythrocytes than peripheral adult erythrocytes.
Drug induced lupus is an autoimmune condition secondary to drug exposure which leads to development of systemic lupus erythematosus (SLE). However, labelling the culprit drug needs a prudent insight into the pharmacological plausibility of each of the offending drugs in suspicion. Here we present a report where allergen immunotherapy was suspected to cause SLE and a deeper clinico-pharmacological evaluation cleared the air.
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64 members
Bibhuti Saha
  • Tropical Medicine
Sujata Law
  • Department of Biochemistry & Medical Biotechnology
Balaram Ghosh
  • Department of Clinical Pharmacology
Kingshuk Chatterjee
  • Department of Dermatology
Shatavisa Mukherjee
  • Clinical & Experimental Pharmacology
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