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Biomedical subjects

A Pal

Publications and source records attributed to A Pal.

At least 19 recordsLinked to original sources
PubMed2006

Arsenic burden of cooked rice: Traditional and modern methods.

Arsenic contamination of rice by irrigation with contaminated groundwater and secondarily increased soil arsenic compounds the arsenic burden of populations dependent on subsistence rice-diets. The arsenic concentration of cooked rice is known to increase with the arsenic concentration of the cooking water but the effects of cooking methods have not been defined. We tested the three major rice cooking procedures followed globally. Using low-arsenic water (As < 3 microg/L), the traditional method of the Indian subcontinent (wash until clear; cook with rice: water::1:6; discard excess water) removed up to 57% of the arsenic from rice containing arsenic 203-540 microg/kg. Approximately half of the arsenic was lost in the wash water, half in the discard water. A simple inexpensive rice cooker based on this method has been designed and used for this purpose. Despite the use of low-arsenic water, the contemporary method of cooking unwashed rice at rice:water::1:1.5-2.0 until no discard water remains did not modify the arsenic content. Preliminary washing until clear did remove 28% of the rice arsenic. The results were not influenced by water source (tubewell, dug well, pond or rain); cooking vessel (aluminium, steel, glass or earthenware); or the absolute weight of rice or volume of water. The use of low-As water in the traditional preparation of arsenic contaminated rice can reduce the ingested burden of arsenic.

Arsenic↗
PubMed2006

Enterotoxigenicity of mature 45-kilodalton and processed 35-kilodalton forms of hemagglutinin protease purified from a cholera toxin gene-negative Vibrio cholerae non-O1, non-O139 strain.

Cholera toxin gene-negative Vibrio cholerae non-O1, non-O139 strain PL-21 is the etiologic agent of cholera-like syndrome. Hemagglutinin protease (HAP) is one of the major secretory proteins of PL-21. The mature 45-kDa and processed 35-kDa forms of HAP were purified in the presence and absence of EDTA from culture supernatants of PL-21. Enterotoxigenicities of both forms of HAP were tested in rabbit ileal loop (RIL), Ussing chamber, and tissue culture assays. The 35-kDa HAP showed hemorrhagic fluid response in a dose-dependent manner in the RIL assay. Histopathological examination of 20 microg of purified protease-treated rabbit ileum showed the presence of erythrocytes and neutrophils in the upper part of the villous lamina propria. Treatment with 40 microg of protease resulted in gross damage of the villous epithelium with inflammation, hemorrhage, and necrosis. The 35-kDa form of HAP, when added to the lumenal surface of rat ileum loaded in an Ussing chamber, showed a decrease in the intestinal short-circuit current and a cell rounding effect on HeLa cells. The mature 45-kDa form of HAP showed an increase in intestinal short-circuit current in an Ussing chamber and a cell distending effect on HeLa cells. These results show that HAP may play a role in the pathogenesis of PL-21.

Animals↗
PubMed2006

Histopathological changes in experimental cholera with a non toxigenic non- O1 non-O139 Vibrio cholerae strain isolated from Kolkata, India.

This study was conducted to understand the pathophysiological changes in experimental rabbit ileal loop model using the Vibrio cholerae strain non-O1non-O139, isolated as sole pathogen from clinically diagnosed cholera patients in Kolkata. Significant amount of haemorrhagic fluid accumulation was observed in all the test loops of rabbit model where the strain of V.cholerae was inoculated as compared to control loops. Microscopic examination of the accumulated fluid showed the presence of erythrocytes and pus cells. Histology revealed structural alteration of the villous epithelium with inflammatory cells infiltration in all the layers of the gut mucosa including the nerve plexus region. Preliminary observation with a haemagglutinin protease extracted from the non-O1 non-O139 strain, was also studied in different concentrations in the same animal model which showed similar type of macroscopic and microscopic response in the ileal loops as seen with the original strain. The results highlight that along with other pathways, inflammatory cells and the enteric neurons have an important role in the pathophysiology of diarrhoea and the isolated protease may be the probable virulence factor in initiating the disease process in this non-O1non-O139 strain induced cholera.

Animals↗
PubMed2006

Biological activity of residual cell-substrate DNA.

Vaccines and other biological products manufactured in cells contain contaminating residual DNA derived from that production cell substrate, with the amount and form of this DNA depending mainly on the type of vaccine. The potential risk of this cellular DNA has been debated for over 40 years without resolution. Opinions on residual DNA have varied from it being considered an inert contaminant, and thus its presence should not be deemed to be a risk to vaccine recipients, to it being considered an important risk factor, particularly for vaccines manufactured in certain cell substrates, such as cells derived from tumours or cells that are tumorigenic. We are not of the opinion that DNA can be considered biologically inert, but whether or what risk residual cell-substrate DNA poses remains to be determined. In this paper, we discuss our approaches to address this issue and describe some preliminary work.

Carcinogens↗
PubMed2005

Isolation of integral membrane proteins of Leishmania promastigotes and evaluation of their prophylactic potential in hamsters against experimental visceral leishmaniasis.

The integral membrane proteins (IMP's) of promastigotes of two virulent strain of Leishmania (L.) donovani Dd8 and Leishmania (L.) infantum LV9 and one avirulent viscerotropic strain Leishmania tropica UR6 were extracted by phase separation technique using a non-ionic detergent "Triton X-114". This detergent is homogeneous at 0 degrees C but divides in an aqueous phase and a detergent phase at above 20 degrees C. The phase partition resulted in solubilisation of hydrophilic proteins in aqueous phase, and IMP's with an amphiphilic nature were recovered in the detergent phase. The strain wise quantitative recovery rates of IMP's were estimated. These proteins were purified by chill methanol centrifugation and used as vaccinogen, alone or in combination with adjuvant against L. donovani challenge in hamster model. Among all the combinations, hamsters immunised with IMP of L. donovani (Dd8) in combination with CFA resulted in 75% parasite inhibition in spleen (P <0.001), however, 61.14% (P <0.001) and 77.60% (P <0.001) parasitic inhibition was achieved in liver and bone marrow respectively as compared to their unvaccinated counter part. Similar combinations with UR6 and LV9 strain inhibited the parasite establishment up to 65.12% (P <0.001) and 66.87% (P <0.001), respectively on splenic site. The specific IgG level against (Dd8 strain) soluble leishmania promastigote antigen was monitored at different stages by enzyme linked immunosorbent assay (ELISA) corresponds to the level of parasitic establishment. Similar observations were made in cases of LV9 and UR6 strains. However, significant lymphoproliferative response to IMPs of Dd8 strain (SI 3.5-4.9, P <0.001) was noticed in all IMP + CFA vaccinated animals. Thus, this study will provide a lead for more manipulative trials to develop a subunit vaccine against the fatal disease.

Animals↗
PubMed2005

Radioprotection of turmeric extracts in bacterial system.

The present study investigates the possible role of crude turmeric extracts in radioprotection by a variety of methods. Although curcumin, the main bioactive component of turmeric, has been extensively used in such studies, the efficiency of the crude extracts has been poorly investigated. This study revealed that dimethyl sulfoxide (DMSO) extracts of turmeric produces a significant amount of radioprotection, which is very similar in nature and extent to that imparted by curcumin. Field Inversion Gel Electrophoresis (FIGE) studies also clearly showed the protection offered by turmeric extracts against X-ray induced DNA damage of E. coli WP2s(lambda) cells.

Cell Survival↗
PubMed2005

Quality control of culture media in a microbiology laboratory.

The nature of reporting of a microbiology laboratory depends upon the quality of the culture media used. Quality of media directly affects the observations and inferences drawn from the cultural characteristics of microorganisms. Checking of different parameters of media such as growth supporting characteristics, physical characteristics, gel strength and batch contamination can help to assess their quality. There are different methods to check all these parameters systematically. The meticulous performance of quality control of culture media can assure precision in reporting.

Culture Media↗
PubMed2004

Purification, substrate specificity, and N-terminal amino acid sequence analysis of a beta-lactamase-free penicillin amidase from Alcaligenes sp.

A beta-lactamase-free penicillin amidase from Alcaligenes sp. active against various beta-lactams was purified to homogeneity. The enzyme can hydrolyze penicillin G to 6-amino penicillanic acid (6-APA) and furnish penicillin G from 6-APA and phenyl acetic acid by condensation. The penicillin amidase is a heterodimer of subunit masses of 63 kDa and 22 kDa, respectively. Its isoelectric point is at pH 8.5. Cephalothin was found to be the best substrate. This is a novel type II penicillin amidase which shares the properties of both type II and type III enzymes. It is thermostable and, unlike penicillin amidase from A. faecalis, its stability remains unperturbed even in presence of reductant. An inhibition study by 2-hydroxy-5-nitro benzylbromide indicated the involvement of tryptophan in catalysis by the enzyme.

Alcaligenes↗
PubMed2004

Removal of arsenic from water using hardened paste of Portland cement.

Portland cement has been used as a new low-cost adsorbent for the removal of arsenic from the water environment. In the batch experiments conducted at an initial concentration of 0.2 mg l(-1) of arsenate, it was found that up to 95% of arsenate could be removed. Kinetic profiles were developed for various conditions. The effect of adsorbent dose, effects of common ions such as Ca2+, Mg2+, Fe3+/Fe2+, Cl-, SO4(2-), NO3(-), PO4(3-) and the effect of pH was studied. Adsorption isotherm studies were performed and it was observed that the Freundlich isotherm was followed with a better correlation than the Langmuir isotherm. Arsenite could also be removed up to approximately 88% using the same material. A new detection method for arsenate/arsenite was developed for routine analysis of arsenic and used during the entire study.

Adsorption↗
PubMed2002

Superior chemotherapeutic efficacy of amphotericin B in tuftsin-bearing liposomes against Leishmania donovani infection in hamsters.

Chemotherapeutic efficacy of the amphotericin B (Amp B), which is the drug of choice for treatment of the leishmanial infections (kala-azar) that become resistant to the conventional chemotherapy using antimonials, has been examined in the Leishmania donovani infected hamsters after encapsulating the drug in tuftsin-free as well as tuftsin-bearing liposomes. The activity was significantly increased (p < 0.05) by delivering Amp B in tuftsin-free liposomes. This antileishmanial effect of the liposomized Amp B was further increased (p < 0.05) by grafting the natural macrophage-activator tetrapeptide, tuftsin (Thr-Lys-Pro-Arg), on the liposome's surface. This could possibly be attributed to both the enhanced drug tolerance after liposomization as well as to the increased uptake of tuftsin-bearing Amp B-laden liposomes by the macrophages. In addition to the increased efficacy, encapsulation of Amp B in the tuftsin-bearing liposomes also enhanced the drug accessibility to areas (e.g. bone marrow) that are otherwise inaccessible to the free drug. These results further demonstrate the usefulness of tuftsin-bearing liposomes as drug vehicles in treatment of the macrophage-based infections that have been reviewed recently (Agrawal, A.K. and Gupta, C.M. (2000). Tuftsin-bearing liposomes in treatment of macrophage-based infections, Adv. Drug Deliv. Rev., 41, 135-146).

Amphotericin B↗
PubMed2001

C-terminal region amino acid substitutions contribute to catalytic differences between murine class alpha glutathione transferases mGSTA1-1 and mGSTA2-2 toward anti-diol epoxide isomers of benzo[c]phenanthrene.

The molecular basis for catalytic differences between structurally closely related murine class alpha glutathione (GSH) transferases mGSTA1-1 and mGSTA2-2 in the GSH conjugation of anti-diol epoxide isomers of benzo[c]phenanthrene (anti-B[c]PDE) was investigated. GSH conjugation of both (-)- and (+)-enantiomers of anti-B[c]PDE was observed in the presence of mGSTA1-1 (60 and 40% GSH conjugation, respectively), whereas mGSTA2-2 exhibited a preference for the (-)-anti-isomer (>97%). In addition, the specific activity of mGSTA2-2 toward the (-)-anti-B[c]PDE isomer was relatively higher than that of mGSTA1-1. The amino acid sequences of mGSTA1-1 and mGSTA2-2 differ at 10 positions that are distributed in three sections. Section I contains amino acid residues in positions 65 and 95; section II contains residues in positions 157, 162, and 169, and section III contains residues in positions 207, 213, 218, 221, and 222. Enzyme activity measurements with chimeras of mGSTA1-1 and mGSTA2-2 revealed that amino acid substitutions in section III account for their differential enantioselectivity and catalytic activity toward anti-B[c]PDE. Site-directed mutagenesis of amino acid residues in section III of mGSTA2-2 with corresponding residues of mGSTA1-1 followed by activity measurements of the wild type and mutated enzymes indicates that leucine 207 and phenylalanine 221 may be critical for the high catalytic activity of mGSTA2-2 toward (-)-anti-B[c]PDE. Molecular modeling studies demonstrated that the active site of mGSTA1-1 accommodates both enantiomers of anti-B[c]PDE, whereas the (-)-anti-isomer interacts more favorably with active site residues in mGSTA2-2. The results of this study clearly indicate that amino acid substitutions in the C-terminal region contribute to catalytic differences between mGSTA1-1 and mGSTA2-2 with respect to anti-B[c]PDE.

Amino Acid Substitution↗
PubMed2001

Evidence of calcium influx across the plasma membrane depends upon the initial rise of cytosolic calcium with activation of IP(3) in rat enterocytes by heat-stable enterotoxin of Vibrio cholerae non-O1.

In response to heat-stable enterotoxin of Vibrio cholerae non-O1, the initial rise of cytosolic Ca(2+) occurred with activation of IP(3). Chelation of extracellular Ca(2+) with EGTA and suspension of cells in Ca(2+) free buffer both demonstrated the involvement of internal stores in the rise of [Ca(2+)]i. Cells pretreated with dantrolene resulted in decrease of [Ca(2+)]i response which suggested that the rise of intracellular level of Ca(2+) was mostly due to the mobilization from IP(3) sensitive stores. When the cytosolic Ca(2+) was chelated by loading the cells with BAPTA, NAG-ST could not induce Ca(2+) entry to the cell as assessed by Mn(2+) quenching of fura-2 fluorescence which suggested that calcium influx across the plasma membrane depends upon initial rise of this bivalent cation that maintained the sustained phase of [Ca(2+)]i response. Addition of toxin to the fura-2-loaded cells, preincubated with lanthanum chloride, resulted in reduction of [Ca(2+)]i level with a short duration of irregular sustained phase further suggesting that the influx of Ca(2+) across the plasma membrane might be through the calcium channel.

Animals↗
PubMed2001

Inhibition of HIV-1 virion production by a transdominant mutant of integrase interactor 1.

Integase interactor 1 (INI1), also known as hSNF5, is a protein that interacts with HIV-1 integrase. We report here that a cytoplasmically localized fragment of INI1 (S6; aa183-294) containing the minimal integrase-interaction domain potently inhibits HIV-1 particle production and replication. Mutations in S6 or integrase that disrupt integrase-INI1 interaction abrogated the inhibitory effect. An integrase-deficient HIV-1 transcomplemented with integrase fused to Vpr was not affected by S6. INI1 was specifically incorporated into virions and was required for efficient HIV-1 particle production. These results indicate that INI1 is required for late events in the viral life cycle, and that ectopic expression of S6 inhibits HIV-1 replication in a transdominant manner via its specific interaction with integrase within the context of Gag-Pol, providing a novel strategy to control HIV-1 replication.

Base Sequence↗
PubMed2001

Comparison of the effects of recombinant adenovirus-mediated expression of wild-type p53 and p27Kip1 on cell cycle and apoptosis in SUDHL-1 cells derived from anaplastic large cell lymphoma.

Recombinant adenoviruses expressing wild-type p53 (AdWTp53) and p27KiP1 (Adp27) were used to compare the effects on cell cycle and apoptosis in SUDHL-1 cells derived from human anaplastic large cell lymphoma. Cells infected with AdWTp53 and Adp27 showed high level of wild-type p53 and p27KiP1 expression, respectively. The expression of these proteins resulted in G1 arrest after 24 h of infection. Although the cells persisted in G1 arrest in both cell populations after 48 and 72 h of infection, the level of apoptosis assessed by TUNEL analysis was higher in cells infected with AdWTp53. Interestingly, apoptosis was more pronounced in cells infected with Adp27 after the initial 24 h and reached a steady state at 48 and 72 h. A lower MOI of Adp27 resulted in G1 arrest associated with a low level of apoptosis in SUDHL-1 cells after 48 h of infection. This was correlated with lower expression of p27KiP1. We postulate that the time-lag and the different level of apoptosis occurring in SUDHL-1 cells infected with AdWTp53 and Adp27 are clearly related to the intrinsic biochemical pathways solicited. In this context our study provides a model to investigate these pathways and better understand the biology of this particular lymphoma. Our data also support a potential application of Adp27 for gene therapy of this lymphoma similarly to AdWTp53 as previously shown.

Adenoviridae↗