Biomedical subjects

A Bhattacharya

Publications and source records attributed to A Bhattacharya.

At least 19 recordsLinked to original sources

PubMed2006

Distribution and possible source of trace elements in the sediment cores of a tropical macrotidal estuary and their ecotoxicological significance.

The paper presents the first document regarding concentration, distribution and possible sources of selected trace elements (Cu, Fe, Mn, Zn, Cr, Co, Ni, Pb, Al, B and Ba) in core sediments (<63 micro particle size) from the lower stretch of Hugli (Ganges) estuary, northeast coast of Bay of Bengal by ICP-AES and EDXRF to evaluate geochemical processes influencing their distribution and possible environmental consequences. The levels of elements showed a wide range of variations in different core depths, in upper and lower intertidal zones as well as among three sampling stations. The most interesting feature of the study is the downward increase of concentrations of majority of the elements reaching overall maximum values at a depth of 20-28 cm in upper littoral zone of the site located in the extreme downstream stretch of the estuary. Values of organic carbon showed very strong positive correlations with most of the elements as revealed by correlation matrix (r) values. The interelemental relationship revealed the identical behavior of element during its transport in the estuarine environment. The overall variation in concentration can be attributed to differential discharge of untreated effluents originating from industrial, agricultural, and aquacultural sources as well as from domestic sewage along with the fishing and boating activities. The resulting compositional dataset was tested by principal component analyses and cluster analyses. Pollution load index (PLI) and index of Geoaccumulation (Igeo) revealed overall low values but the enrichment factors (EFs) for Pb were typically high for all the stations. The mean concentrations of Zn and to some extent Cu exceeded the Effects Range-Low (ER-L) values in the majority of the cases indicating that there may be some ecotoxicological risk to organisms living in sediments. The concentration of the trace elements reported in this work is useful as baselines for comparison in future sediment quality studies.

Carbon↗

PubMed2006

Effect of head-tail ratio and the range of the head-head interaction in amphiphilic self-assembly.

We investigate cluster autocorrelations, critical micelle concentration (CMC), and size distribution for amphiphiles of the type H(x)T(y) as a function of the amphiphilic factor alpha = x/y for a fixed length l = x + y using a combination of reptation and kink-jump Monte Carlo (MC) moves in a two-dimensional (2D) square lattice. We find that the CMC decreases monotonically as a function of the alpha-parameter. For a fixed chain length l of the molecule, the symmetric molecules of the type H(l/2)T(l/2) with alpha = 1 tend to form circular micelles with relatively narrow distribution in cluster sizes. As we decrease the alpha-parameter to introduce head-tail asymmetry, the size distribution becomes polydisperse with occurrences of more elongated micelles. A calculation of the cluster autocorrelation function reveals that for the same chain length, symmetric amphiphiles take significantly less time to equilibrate and therefore simulation of much longer molecules is possible. Next we study the effect of the head-head repulsion term beyond next nearest neighbors. In general, the presence of a longer-range repulsive interaction reduces the average size of the micelles. We also notice that for l = 5, while H(2)T(3) molecules produces spherical micelles, the H(1)T(4) molecules( alpha = 0.25) often form vesicles. Our systematic studies bring out relevant information for controlling shapes and sizes of micelles to be used as templates in the design of self-assembled nanostructures.

Cluster Analysis↗

PubMed2006

Potentiation of irinotecan sensitivity by Se-methylselenocysteine in an in vivo tumor model is associated with downregulation of cyclooxygenase-2, inducible nitric oxide synthase, and hypoxia-inducible factor 1alpha expression, resulting in reduced angiogenesis.

Until recently, the use of Se-methylselenocysteine (MSC) as selective modulator of the antitumor activity and selectivity of anticancer drugs including irinotecan, a topoisomerase I poison, had not been evaluated. Therapeutic synergy between MSC and irinotecan was demonstrated by our laboratory in mice bearing human squamous cell carcinoma of the head and neck tumors. In FaDu xenografts, a poorly differentiated tumor-expressing mutant p53, the cure rate was increased from 30% with irinotecan alone to 100% with the combination of irinotecan and MSC. Cellular exposure to cytotoxic concentration of SN-38, the active metabolite of irinotecan (0.1 microM) alone and in combination with noncytotoxic concentration of MSC (10 microM) did not result in additional enhancement of chk2 phosphorylation and downregulation of specific DNA replication-associated proteins, cdc6, MCM2, cdc25A, nor increase in PARP cleavage, caspase activation and the 30-300 kb DNA fragmentation induced by SN-38 treatment. MSC did not alter significantly markers associated with apoptosis, nor potentiate irinotecan-induced apoptosis. These results indicate that apoptosis is unlikely to be one of the main mechanism associated with the observed in vivo therapeutic synergy. In contrast, significant downregulation of cyclooxygenase-2 (COX-2) expression and activity was observed in the cells exposed to SN-38 in combination with MSC compared to SN-38 alone. Moreover, the inhibition of PGE(2) production was also observed in the cells treated with the combination as compared with SN-38 alone. Analysis of tumor tissues at 24 h after treatment with synergistic modality of irinotecan and MSC revealed significant downregulation of COX-2, inducible nitric oxide synthase (iNOS) and hypoxia-induced factor-1alpha expression (HIF 1alpha). Moreover, decreased microvessel density was observed after irinotecan treatment with the addition of MSC. These results suggest that observed therapeutic synergy correlates with the inhibition of neoangiogenesis through the downregulation of COX-2, iNOS and HIF-1alpha expression.

Animals↗

PubMed2006

Use of two unrelated umbilical cord stem cell units in stem cell transplantation for Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome, an X-linked primary immunodeficiency can be cured by bone marrow transplantation. Umbilical cord haemopoietic stem cells are increasingly used as an alternative to bone marrow; advantages include ready availability, no risk to the donor, low rate of viral contamination, and low risk of graft versus host disease. Disadvantages include low stem cell dose for larger patients and lack of stem cells for boost infusions following the initial procedure. We report the case of a child with Wiskott-Aldrich syndrome who underwent cord blood stem cell transplantation with two separate cord blood units, 8 days apart.

Cord Blood Stem Cell Transplantation↗

PubMed2006

Omega-3 fatty acid effect on alveolar bone loss in rats.

Gingival inflammation and alveolar bone resorption are hallmarks of adult periodontitis, elicited in response to oral micro-organisms such as Porphyromonas gingivalis. We hypothesized that omega (omega)-3 fatty acids (FA) dietary supplementation would modulate inflammatory reactions leading to periodontal disease in infected rats. Rats were fed fish oil (omega-3 FA) or corn oil (n-6 FA) diets for 22 weeks and were infected with P. gingivalis. Rats on the omega-3 FA diet exhibited elevated serum levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), documenting diet-induced changes. PCR analyses demonstrated that rats were orally colonized by P. gingivalis; increased IgG antibody levels substantiated this infection. P. gingivalis-infected rats treated with omega-3 FA had significantly less alveolar bone resorption. These results demonstrated the effectiveness of an omega-3 FA-supplemented diet in modulating alveolar bone resorption following P. gingivalis infection, and supported that omega-3 FA may be a useful adjunct in the treatment of periodontal disease.

Alveolar Bone Loss↗

PubMed2005

Effect of fish oil on offensive and defensive factors in gastric ulceration in rats.

The effect of fish oil (FO) derived from Scomberoides commersonianus containing omega-3 polyunsaturated fatty acids was studied on gastric ulcers and as well as on offensive and defensive factors in gastric mucosal damage, following experimental gastric ulceration. FO significantly reduced the severity of ulceration in gastric ulcers induced by aspirin, cold-restraint stress (CRS), alcohol, and pylorus ligation. The results also indicated the potentiality of FO in maintaining the integrity of gastric mucosa by virtue of its effect on both offensive and defensive gastric mucosal factors. It decreased the offensive acid-pepsin secretion and augmented the defensive factors like mucin secretion, cellular mucus and life span of mucosal cells following pylorus ligation. FO significantly increased activity of anti-oxidant enzymes (catalase and glutathione peroxidase) and decreased lipid peroxidation in gastric mucosa of CRS rats. The study indicates the beneficial role of FO in gastric ulceration by inhibition of offensive mucosal factors and oxidative stress, and augmentation of defensive mucosal factors.

Animals↗

PubMed2005

Electrostatic tuning of the superconductor-insulator transition in two dimensions.

Superconductivity has been induced in insulating ultrathin films of amorphous bismuth using the electric field effect. The screening of the electron-electron interaction was found to increase with electron concentration in a manner correlated with the tendency towards superconductivity. This does not preclude an increase in the density of states being important in the development of superconductivity. The superconductor-insulator transition appears to belong to the universality class of the three dimensional XY model.

Journal Article↗

PubMed2005

Ambipolar gate effect and low temperature magnetoresistance of ultrathin La0.8Ca0.2MnO3 films.

Ultrathin La(0.8)Ca(0.2)MnO(3) films have been measured in a field-effect geometry. The gate electric field produces a significant ambipolar decrease in resistance at low temperatures. This is attributed to the development of a pseudogap in the density of states and the coupling of localized charge to strain. Within a mixed phase scenario, the gate effect and magnetoresistance are interpreted in the framework of a "general susceptibility," which describes how phase boundaries move through a hierarchical pinning landscape.

Journal Article↗

PubMed2005

Outcome of boost haemopoietic stem cell transplant for decreased donor chimerism or graft dysfunction in primary immunodeficiency.

Haemopoietic stem cell transplants (HSCT) cure increasing numbers of primary immunodeficiencies (PID): residual recipient T-cell function increases risk of incomplete or decreasing immune reconstitution, which may resolve following a second, unconditioned, infusion from the same donor (boost infusion). We assessed the outcome of 20 boost infusions in 19/139 patients transplanted for PID patients at our centre since 1987. Boost infusion was given 64-1226 days after the original HSCT. Follow-up was 4-124 months. In all, 12 of 19 patients cleared viral infection (6), or showed sustained increase in donor chimerism, T- and B-cell numbers and function, or other markers (6). In 7/12 patients, immunoglobulin replacement has been discontinued. Four were partially successful with stable low-level chimerism (two patients) or improved T-cell function, but not B cell function (two patients). Four failed with no change in donor chimerism or cell number. No significant association with donor source, T-cell depletion, conditioning regimen, boost infusion stem cell dose or time from original HSCT to boost was found. One patient developed grade III acute graft-versus-host disease despite cyclosporine, and one developed severe pneumonitis; both have recovered. Boost infusion was successful or partially successful in 84% of patients. The risk of adverse effects is low.

Follow-Up Studies↗

PubMed2005

Single centre experience of umbilical cord stem cell transplantation for primary immunodeficiency.

Primary immunodeficiencies (PID) are an important cause of childhood mortality. Haematopoietic stem cell transplantation (HSCT) is the best treatment for many PID. Umbilical cord stem cells are an alternative source of HSC. There is little data regarding outcome of umbilical cord stem cell transplantation (UCSCT) for PID. Our single centre experience is reported. A retrospective study of 14 of 148 patients transplanted for PID, who have received 15 UCSCT was performed, with specific regard to graft-versus-host disease (GvHD) and immune reconstitution. Eight patients with severe combined immunodeficiency (SCID), and six with other combined immunodeficiencies were treated. Of the patients, 12 received unrelated cords, and two had sibling transplants. Median age at transplant was 3.5 months, median nucleated cell dose was 0.8 x 10(8)/kg. All engrafted. Median time to neutrophil engraftment was 22 days, median time to platelet engraftment was 51 days. One developed significant grade III GvHD post transplantation. In total, 11 patients had full donor T and six full donor B-cell chimerism, six of nine patients >1 year post-BMT had normal IgG levels and specific antibody responses to tetanus and Hib vaccines; two are being assessed. Two patients died of multi-organ failure related to pre-existing infection and inflammatory complications respectively. UCSCT should be considered for patients requiring stem cell therapy for PID.

Antibody Formation↗

PubMed2005

Extrahepatic portal hypertension: quality of life and somatic growth after surgery.

AIM: This study was carried out in order to determine whether children with extrahepatic portal hypertension show any improvement in growth parameters and quality of life after elective surgery. PATIENTS AND METHODS: All patients with extrahepatic portal hypertension who underwent surgery between April 1999 and March 2002 were studied prospectively. Height and weight before and after surgery were converted into Z scores for comparison. The quality of life was assessed by changes in scholastic ability, physical activity, social interaction, and economic effects on the family. RESULTS: At the end of a minimum follow-up period of 1 year, of the 30 children, 50 % and 76 % showed improvement in weight and height Z scores, respectively, compared to their scores while on medical management. Z scores below - 2 SD for weight and height were seen in 57 % and 37 % of patients prior to surgery, and only in 40 % and 20 %, respectively at the end of follow-up, which ranged from 1 - 4 years. The improvement in height and weight was more in those who had undergone splenectomy with either devascularization or central splenorenal shunt compared to those who had undergone side-to-side lienorenal shunt without splenectomy. The children, who had dropped out of school while on medical management, either rejoined school or attended vocational courses after surgery. There was an improvement in school performance and physical activity in 85 % of the children. Improvement in personality was seen in 73 % of the affected patients. The cost incurred for surgery was one-third of the amount spent while on medical management. CONCLUSIONS: Growth parameters improved significantly in children after surgical intervention for portal hypertension. Overall improvement in scholastic abilities, physical activity, and social interaction was noted in a majority of the patients. As a one-time procedure in a developing country, surgery is also more cost effective.

Adolescent↗

PubMed2005

The vesicoureteral reflux dysplasia syndrome in patients with posterior urethral valves.

PURPOSE: We retrospectively reviewed outcomes in children followed for posterior urethral valves and the vesicoureteral reflux dysplasia (VURD) syndrome. MATERIALS AND METHODS: Of 65 patients with posterior urethral valves 13 fulfilled the criteria for the VURD syndrome. Patients were assessed with diethylenetriamine pentaacetic acid and dimercapto-succinic acid scans at followup to evaluate stability of renal function, presence of renal scarring and drainage of the contralateral kidney. Student's t test and the chi-square test were used for statistical analysis, with p < or = 0.05 considered significant. RESULTS: Based on the dimercapto-succinic acid scan reports, patients were classified into group 1 (6 patients), in which the contralateral kidney had no evidence of scarring, and group 2 (7 patients), in which the contralateral kidney had evidence of scars. Patients in group 1 had no breakthrough urinary tract infections or history of urinary incontinence. There was no dilatation of the contralateral upper urinary tract, and 5 of 6 patients had prompt ureteral drainage on scans. They also attained a long-term serum creatinine of 0.6 +/- 0.0 mg/dl. Patients in group 2 had a significant incidence of breakthrough urinary tract infections (p < or = 0.03) and diurnal incontinence (p < or = 0.01). Hydroureteronephrosis and slow drainage were seen in 6 of 7 patients on scans. The long-term mean serum creatinine attained in this group was 0.9 +/- 0.3 mg/dl. CONCLUSIONS: About half of the patients with the VURD syndrome had renal scarring in the contralateral kidney. These patients had evidence of hydroureteronephrosis, slow drainage of the ureter in association with breakthrough urinary tract infections and diurnal incontinence. Although serum creatinine in patients with the VURD syndrome and renal scarring in the contralateral kidney was not statistically different from that in children with a normal contralateral kidney in the short term, in the long term the deleterious effects of renal scarring, viz hypertension, proteinuria and renal failure, are likely to manifest. The presence of the VURD syndrome may not always be as good a prognostic indicator as believed previously.

Child↗

PubMed2005

Paenibacillus assamensis sp. nov., a novel bacterium isolated from a warm spring in Assam, India.

A polyphasic approach was used to characterize a bacterium, GPTSA 11(T), isolated from a warm spring located in a reserve forest in Assam, India. The cells are Gram-variable, strictly aerobic, sporulating motile rods. The major fatty acids of the strain are C(15 : 0) anteiso (48.42 %), C(16 : 0) iso (11.59 %), C(16 : 1)omega11c (6.16 %), C(15 : 0) iso (6.03 %), C(17 : 0) anteiso (5.68 %) and C(16 : 1)omega7c alcohol (5.01 %). The presence of the fatty acid C(16 : 1)omega7c alcohol distinguishes this strain from other closely related species of the genus Paenibacillus. The strain contains MK-7 as the diagnostic menaquinone. The G+C content of the genomic DNA is 41.2 mol%. Analysis of the 16S rRNA gene sequence (1466 nt) revealed the presence of signature sequences PAEN 515F (5'-GAGTAACTGCTCTCGGAATGACGGTACTTGAGAAGAAAGCCCC-3') and PAEN 862F (5'-TCGATACCCTTGGTGCCGAAGT-3'), which were found in the species of the genus Paenibacillus surveyed by Shida et al. [Shida, O., Takagi, H., Kadowaki, K., Nakamura, L. K. & Komagata, K. (1997). Int J Syst Bacteriol 47, 289-298]. The sequence shows closest similarity (95.85 %) to that of Paenibacillus apiarius, followed by Paenibacillus alvei (94.34 %), Paenibacillus cineris (93.87 %), Paenibacillus favisporus (93.80 %), Paenibacillus chibensis (93.47 %) and Paenibacillus azoreducens (93.40 %). Biochemical, physiological, chemotaxonomic and phylogenetic analyses justify placement of the strain in the genus Paenibacillus but not within any existing species. It should, therefore, be considered as representing a novel species, for which the name Paenibacillus assamensis sp. nov. is proposed. The type strain is GPTSA 11T (=MTCC 6934T=JCM 13186T).

DNA, Bacterial↗

PubMed2005

Peritoneo-scrotal communication: demonstration by 99mtechnetium sulphur colloid scintigraphy.

Continuous ambulatory peritoneal dialysis is a widely used and convenient alternative to haemodialysis in patients with renal failure. Occasionally, a scrotal swelling may develop during this procedure because of fluid passing through a patent processus vaginalis. We present a case report to illustrate the diagnostic use of radionuclide scintigraphy in this group of patients.

Aged↗

PubMed2005

Technetium-99m ciprofloxacin imaging in the diagnosis of postsurgical bony infection and evaluation of the response to antibiotic therapy: A case report.

The use of radiolabelled antibiotics is fast emerging as a promising diagnostic test for the detection of infective lesions, because of their specific binding to the bacterial component. Ciprofloxacin is a broad-spectrum antibiotic that has been used as a radiolabelled antibiotic in both the diagnosis of infections in rabbits and in clinical trials on humans. The diagnosis of skeletal microbial infections remains a challenge, especially in orthopaedic patients with implants. We present a case report of a patient with undiagnosed and unrelenting pain in the lower third of the left leg, which had persisted for 6 months. A novel scintigraphy, which was developed in-house using a 99mTC ciprofloxacin single vial kit, was used for diagnosing the active bacterial infection. A 99mTC methylene diphosphonate bone scan was also performed to locate precisely the site of the lesion. Gradually increasing concentrations of both the radiotracers confirmed the presence of active bacterial infection in the distal third of the left tibia. Follow-up scanning after antibiotic therapy showed the disappearance of the pooling of 99mTC ciprofloxacin, indicating a good response. Therefore, 99mTC ciprofloxacin has good diagnostic and prognostic applications in deep-seated covert skeletal microbial infections. However, the persistence of a focal concentration detected by the 99mTC methylene diphosphonate scan was attributed to the inflammatory and not the infective pathology.

Adult↗

PubMed2004

Evaluation of the concentration of HCH, DDT, HCB, PCB and PAH in the sediments along the lower stretch of Hugli estuary, West Bengal, northeast India.

Detailed analyses of persistent organic pollutants (POPs) such as hexachlorocyclohexane (HCH) isomers (HCHs), dichlorodiphenyltrichloro ethane (DDT) and its metabolites (DDTs), hexachlorobenzene (HCB) and congeners of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the coastal estuarine environment of West Bengal, northeast India allowed the evaluation of the contamination status, distribution and possible pollution sources. HCH, DDT, HCB, PCB and PAH were identified compounds in all the samples, whereas the concentrations of chlorinated pesticides (trans-eptachlorepoxide, dieldrin, endrin, metaoxychlor and mirex) were below the detection limits and were not of great concern. The pesticides did demonstrate markedly different distributions reflecting different agricultural and domestic usage in the region. The range of concentrations of HCH, HCB, DDT and PCBs in the sediments were 0.11-0.40, <0.05-0.98, 0.18-1.93 and 0.18-2.33 ng/g dry wt, respectively. Overall elevated levels of HCB, DDT and PCB were recorded at Babughat, a very closely located site of the metropolitan megacity Calcutta. Fluoranthene (flu) and pyrene (py), the dominant 4-ring PAHs, also showed an abrupt elevated concentrations at Babughat with values of 214 and 144 ng/g dry wt, respectively. Among the isomers and metabolites of HCH, DDT and PCB, alpha-HCH, pp'-DDT and PCB (101), PCB (118), PCB(153) and PCB (138) were found to be dominant. High ratios of metabolites of DDT to SigmaDDTs reveal recent use of DDT in this coastal environment. Fluoranthene, pyrene, 1,2-benzo(a)anthracene and chrysene formed the dominant congeners out of 19 identified PAHs. The sources of contamination are closely related to human activities such as domestic and industrial discharge, automobile exhausts, street runoff, slum sewage, agricultural chemicals and soil erosion due to deforestation as well as atmospheric transport. This study is compared to other coastal and estuarine environments in India and abroad. The baseline data can be used for regular ecological monitoring, considering the industrial and agricultural growth around this important estuarine ecosystem.

Agriculture↗

PubMed2004

Posterior urethral valves: incidence and progress of vesicoureteric reflux after primary fulguration.

This is a prospective study of 20 cases of posterior urethral valves (PUV) presenting between the ages of 12 days and 5.5 years (median 15 months) in order to determine the incidence and progress of vesicoureteric reflux (VUR), hydronephrosis (HN), and renal functional status. The efficacy of fulguration as the sole modality of treatment for PUV was assessed in terms of improvement or disappearance of VUR over a 6-month follow-up period. VUR was present in 60% of the patients, being unilateral in 41.7%. Out of 19 renal units with VUR, reflux subsided in 31.5% by 3 months and 78.94% by 6 months. The blood urea and serum creatinine levels, which were raised in 50% of the patients at presentation, came down to normal by 6 months in all the cases. Improvement in glomerular filtration rates (GFR) was noted in all the children at each follow-up and was found to be statistically significant ( p<0.01). HN was present in all the patients at presentation and was bilateral in 90%. It decreased significantly during the follow-up period, though its complete disappearance was seen only in one case. Vesicoureteric reflux dysplasia syndrome (VURD) was present in two cases. Our study showed that VUR disappeared in a majority of the cases by 6 months once adequate urethral patency was restored, although hydronephrosis persisted.

Child, Preschool↗

PubMed2004

The clinical and biological overlap between Nijmegen Breakage Syndrome and Fanconi anemia.

Fanconi anemia (FA), an autosomal recessive chromosomal instability syndrome, is characterized clinically by developmental abnormalities, growth retardation, progressive bone marrow failure, pancytopenia, and pronounced cancer predisposition. Nijmegen Breakage Syndrome (NBS) is a related disorder that shares overlapping clinical features, principally, developmental delay, microcephaly, and cancer predisposition. The diagnosis has relied on chromosomal instability following exposure to DNA cross-linking agents in FA and to ionizing radiation (IR) in NBS. We describe two patients who clinically had FA, but showed sensitivity to both DNA cross-linking agents and ionizing radiation, and who were found to have a rare mutation in the NBS gene. The importance of genetic diagnosis with respect to treatment and prognosis is discussed.

Abnormalities, Multiple↗