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Biomedical subjects

T Das

Publications and source records attributed to T Das.

At least 73 records · Page 4Linked to original sources
PubMed1999

Validation of a Bengali adaptation of the Conners' Parent Rating Scale (CPRS-48).

BACKGROUND: The Conners' Parent Rating Scales (CPRS) have been used to measure behavioural problems in drug trials in children for many years. This study in rural India aimed to validate a translated version of the CPRS-48 for use in a study of anti-epileptic drug side-effects. METHOD: The Scale was translated into local dialect, back-translated, and piloted among healthy families. The revised version was then administered to mothers of 60 healthy children and 63 children with epilepsy. Tests of internal reliability, test-retest reliability and factor analysis were performed. RESULTS: Cronbach's alpha ranged from 0.60 to 0.75 for the subscales, and correlation coefficients after retesting from 0.84 to 0.99. The overall factor structure was very similar to that reported in the original USA sample. CONCLUSION: The Bengali version of the CPRS-48 and its Hyperactivity Index have validity for rural Bengali children, and the process demonstrates that such instruments can be usefully adapted for local purposes.

Analysis of Variance↗
PubMed1999

Hypodermic needles: a new source of penetrating ocular trauma in Indian children.

PURPOSE: To study the clinico-microbiologic profile and visual prognosis of ocular injuries caused by disposable hypodermic needles used by children to squirt water. METHODS: We analyzed 19 consecutive cases of hypodermic needle injury seen at our institute. RESULTS: The average age of the patients was 10.3 years (range, 4-20 years). A small self-sealed corneal or scleral laceration was seen in 11 eyes; in 8 eyes, the site of injury was occult. Initial visual acuity was no light perception (3 eyes) or hand motion or light perception (16 eyes). Surgery in 18/19 eyes included vitrectomy with intraocular antibiotic injections for endophthalmitis (14 eyes), evisceration for panophthalmitis (2 eyes), and cataract extraction for traumatic cataract (2 eyes). Final visual acuity was no light perception or light perception only in 10 eyes, 20/400-20/60 in three eyes, and 20/40 or better in six eyes. CONCLUSIONS: Severe ocular morbidity may result from improper disposal of hypodermic needles.

Adolescent↗
PubMed1998

Protein A induces NO production: involvement of tyrosine kinase, phospholipase C, and protein kinase C.

Protein A of S. aureus exhibits a wide array of immunopotentiating activities. Since the role of nitric oxide (NO) in bioregulation has been well envisaged; we studied the effect of Protein A on NO production by immunocytes both in vivo and in vitro. Our data indicate that PA at a comparable dose of LPS (lipopolysaccharide) increases the NO levels in the serum of Swiss albino mice by about 12-fold from its basal level. The peak level is reached at about 12 hours after i.p. inoculation of PA. However, NO concentration returns to the basal value 15 hours posttreatment. Splenic lymphocytes and peritoneal macrophages showed appreciable increase in NO production when cultured with PA in vitro. Interestingly, inhibitors of tyrosine kinase, phospholipase C, and protein kinase C (PKC) inhibited NO production in splenic lymphocytes. Thus, it appears that these enzymes participate in the signaling cascade induced by PA, which culminates in the production of NO downstream of PKC. It is possible that PA-induced NO production may have relevance with the anti-tumor and anti-parasitic properties of PA, described earlier.

Animals↗
PubMed1998

Mechanism of protein A-induced amelioration of toxicity of anti-AIDS drug, zidovudine.

Long-term treatment with 3-azido-3-deoxy thymidine (AZT) is often associated with myelosuppression. In AZT-treated Swiss mice, similar toxicological manifestations in terms of reduction of red blood and white blood cell counts and hemoglobin content had been observed as in AZT-treated AIDS patients. Pretreatment of animals with Protein A (PA) of Staphylococcus aureus Cowan I (1 microgram/ml), twice a week for two weeks, alleviated such hematopoietic toxicity due to AZT. AZT-induced reduction in colony-forming unit-erythroid (CFU-E) and colony-forming unit-granulocyte monocyte (CFU-GM) were also reversed by the combined treatment of AZT and PA. PA treatment showed an increased level of erythropoietin in the blood plasma, and cellularity of spleen, thymus, and bonemarrow was also increased in the group receiving combined treatment (PA+AZT), higher than that in the AZT group. AZT or its metabolites inhibited the activities of liver microsomal monooxygenases, which, however, could be regenerated in an accelerated manner by pretreatment of mice with PA. Moreover, the PA-treated group showed an accelerated clearance of AZT and/or its metabolites. These results suggest that such an immunopharmacologic approach might substantially reduce the toxic effects of drugs, such as AZT.

Anemia↗
PubMed1998

RNA polymerase of vesicular stomatitis virus specifically associates with translation elongation factor-1 alphabetagamma for its activity.

An RNA-dependent RNA polymerase is packaged within the virions of purified vesicular stomatitis virus, a nonsegmented negative-strand RNA virus, which carries out transcription of the genome RNA into mRNAs both in vitro and in vivo. The RNA polymerase is composed of two virally encoded polypeptides: a large protein L (240 kDa) and a phosphoprotein P (29 kDa). Recently, we obtained biologically active L protein from insect cells following infection by a recombinant baculovirus expressing L gene. During purification of the L protein from Sf21 cells, we obtained in addition to an active L fraction an inactive fraction that required uninfected insect cell extract to restore its activity. The cellular factors have now been purified, characterized, and shown to be beta and gamma subunits of the protein synthesis elongation factor EF-1. We also demonstrate that the alpha subunit of EF-1 remains tightly bound to the L protein in the inactive fraction and betagamma subunits associate with the L(alpha) complex. Further purification of L(alpha) from the inactive fraction revealed that the complex is partially active and is significantly stimulated by the addition of betagamma subunits purified from Sf21 cells. A putative inhibitor(s) appears to co-elute in the inactive fraction that blocked the L(alpha) activity. The purified virions also package all three subunits of EF-1. These findings have a striking similarity with Qbeta RNA phage, which also associates with the bacterial homologue of EF-1 for its replicase function, implicating a possible evolutionary relationship between these host proteins and the RNA-dependent RNA polymerase of RNA viruses.

HeLa Cells↗
PubMed1998

Randomised controlled trial to assess acceptability of phenobarbital for childhood epilepsy in rural India.

BACKGROUND: The use of phenobarbital for childhood epilepsy is controversial because of reported behavioural side-effects; however, whether this research can validly be extrapolated to developing countries is not clear. We undertook a randomised comparison of phenobarbital and phenytoin to assess the acceptability and efficacy of phenobarbital as monotherapy for childhood epilepsy in rural India. METHODS: Between August, 1995, and February, 1996, 109 unselected children aged 2-18 years with partial and generalised tonic-clonic epilepsy were identified by population screening. 15 families declined to take part. 94 children were randomly allocated treatment with phenobarbital (1.5 mg/kg daily for 2 weeks; maintenance dose 3.0 mg/kg daily; n = 47) or phenytoin (2.5 mg/kg daily then 5.0 mg/kg daily; n = 47). Children were followed up for 12 months. The primary outcome measure was the frequency of behavioural side-effects; behaviour was assessed by the Conners parent rating scale for children aged 6 years and older, and by the preschool behaviour screening questionnaire (BSQ) for those aged 2-5 years, at 12 months or at withdrawal from treatment. Analysis was by intention to treat. FINDINGS: The mean log-transformed scores on the behaviour rating scales did not differ significantly between the phenobarbital and phenytoin groups (Conners 2.64 [SD 0.71] vs 2.65 [0.89], p = 0.97; n = 32 in each group: BSQ 2.12 [1.31] vs 2.18 [1.02], p = 0.94; n = 4 vs 3). The odds ratio for behavioural problems (phenobarbital vs phenytoin) was 0.51 (95% CI 0.16-1.59). There was no excess in parental reports of side-effects for phenobarbital. We found no difference in efficacy between the study drugs (adjusted hazard ratio for time to first seizure from randomisation 0.97 [0.28-3.30]). INTERPRETATION: This evidence supports the acceptability of phenobarbital as a first-line drug for childhood epilepsy in rural settings in developing countries.

Adolescent↗
PubMed1998

Comparison of key informant and survey methods for ascertainment of childhood epilepsy in West Bengal, India.

BACKGROUND: This study aimed to compare efficacy and cost of key informants and survey for ascertainment of childhood epilepsy within a treatment context in rural India. METHODS: The study was set in a non-governmental, community programme for the functional and socioeconomic rehabilitation of children with disabilities in rural West Bengal, India. Ascertainment was by two methods: house-to-house survey of 15000 households and also by 430 key informants including village leaders, health workers and 670 schoolchildren. Methods were compared for positive predictive value, and sensitivity by capture-recapture technique. Ninety four children were enrolled into treatment. Predictors of treatment success were determined by multiple logistic regression analysis, giving adjusted odds ratios for remission. The costs of identifying one case and one treatment success were measured by costing personnel, materials and overheads. RESULTS: The survey was four times as sensitive as key informants although the positive predictive values were similar (36%, 40%). The survey had an absolute sensitivity of only 59%. Identification by key informants strongly predicted successful treatment outcome (odds ratio [OR] = 4.74, 95% confidence interval [CI] : 1.19-18.85). The cost of finding one case was US$11 and US$14, and of finding one successful treatment outcome US$35 and US$67 for informants and survey respectively. Key informants were essential in attaining longer term programme objectives. CONCLUSIONS: In the context of a treatment programme, key informants were the more cost-effective method, but community involvement was traded against low sensitivity in the short term. Overall ascertainment costs were significant in the context of primary health care in India.

Child↗
PubMed1998

Choroidal neovascular membrane.

Choroidal neovascular membrane in the macular area is one of the leading causes of severe visual loss. Usually a manifestation in elderly population, it is often associated with age-related macular degeneration. The current mainstay of management is early diagnosis, usually by fundus examination, aided by angiography and photocoagulation in selected cases. Various other modalities of treatment including surgery are being considered as alternate options, but with limited success. The purpose of this review is to briefly outline the current concepts and the management strategy from a clinician's viewpoint.

Aged↗
PubMed1997

Mustard oil and garlic extract as inhibitors of sodium arsenite-induced chromosomal breaks in vivo.

Arsenic, a well-known human carcinogen present as a contaminant in ground water poses a serious threat to public health in various countries. The anticlastogenic properties of two dietary supplements, garlic and mustard oil, were screened against the clastogenic activity of sodium arsenite, since diet may contain factors which affect the process of mutagenesis and carcinogenesis. Aqueous extract of garlic (100 mg/kg b.w.) and mustard oil (0.643 mg/kg b.w.) were fed to Mus musculus for 30 consecutive days either singly or simultaneously. Sodium arsenite (0.1 mg/kg b.w.) was injected subcutaneously on days 7, 14, 21 and 30 of the experiment, singly and together with the dietary supplements. The animals were sacrificed 24 h after the last exposure to sodium arsenite and clastogenic effects were observed in the bone marrow cells. The degree of modulation of sodium arsenite-induced chromosomal aberrations was more pronounced in mustard oil than in garlic extract and simultaneous administration of both the dietary supplements reduced the clastogenic effects of sodium arsenite closer to the level of the negative control. The greater efficacy could be due to the interaction of the two dietary supplements and its radical scavenging property.

Animals↗
PubMed1997

Basic amino acid residues at the carboxy-terminal eleven amino acid region of the phosphoprotein (P) are required for transcription but not for replication of vesicular stomatitis virus genome RNA.

The phosphoprotein (P) of vesicular stomatitis virus (VSV) serotypes New Jersey [P(NJ)] and Indiana [P(I)] contains a highly conserved carboxy-terminal domain which is required for binding to the cognate N-RNA template as well as to form a soluble complex with the nucleocapsid protein N in vivo. We have shown that the deletion of 11 amino acids from the C terminal end of the P(I) protein abolishes both the template binding and the complex forming activity with the N protein. Within this region, there are conserved basic amino acid residues (R260 and K262) that are potential candidates for such interactions. We have generated mutant P proteins by substitution of these basic amino acid residues with alanine and studied their role in both transcription and replication. We have found that the R260A mutant failed to bind to the N-RNA template, whereas the K262A mutant bound efficiently as the wild-type protein. The R260A mutant, as expected, was unable to support mRNA synthesis in vitro in a transcription reconstitution reaction as well as transcription in vivo of a minigenome using a reverse genetic approach. However, the K262A mutant supported low level of transcription (12%) both in vitro and in vivo, suggesting that direct template binding of P protein through the C-terminal domain is necessary but not sufficient for optimal transcription. Using a two-hybrid system we have also shown that both R260A and K262A mutants interact inefficiently with the L protein, suggesting further that the two point mutants display differential phenotype with respect to binding to the template. In addition, both R260A and K262A mutants were shown to interact efficiently with the N protein in vivo, indicating that these mutants form N-P complexes which are presumably required for replication. This contention is further supported by the demonstration that these mutants support efficient replication of a DI RNA in vivo. Since the transcription defective P mutants can support efficient replication, we propose that the transcriptase and the replicase are composed of two distinct complexes containing (L-P2-3) and L-(N-P), respectively.

Amino Acid Sequence↗
PubMed1997

Inhibition of clastogenic effects of arsenic through continued oral administration of garlic extract in mice in vivo.

Crude aqueous extract of garlic bulbs (Allium sativum L. single clove variety) was administered by gavage to mice of both sexes daily for up to 30 and 60 days, in doses corresponding to 6 g for a 60 kg human body. Sodium arsenite (at 1/50 of LD50 dose) was injected subcutaneously to mice on every 7th day of the experiment. Chromosome preparations made from bone marrow following flame drying Giemsa schedule were screened for chromosomal aberrations. The clastogenic affects of prolonged exposure to sodium arsenite --a strong clastogen-- was reduced by a highly significant amount when crude garlic extract, in the dose used, was given daily to the mice by intubation for the same period.

Administration, Oral↗
PubMed1997

Phosphorylation of canine distemper virus P protein by protein kinase C-zeta and casein kinase II.

Transcription by nonsegmented negative-strand RNA viruses is mediated by the viral RNA-dependent RNA polymerase and transcriptional cofactor P. The P protein is activated by phosphorylation, an event initiated by cellular kinases. The kinase used differs among this group of RNA viruses; vesicular stomatitis virus and respiratory syncytial virus utilize casein kinase II (CKII), whereas human parainfluenza virus type 3 utilizes PKC isoform zeta (PKC-zeta) for activation of its P protein. To identify the cellular kinase(s) involved in the phosphorylation of the canine distemper virus (CDV) P protein, we used recombinant CDV P in phosphorylation assays with native kinase activities present in CV1 cell extracts or purified CKII and PKC isoforms. Here, we demonstrate that the CDV P protein is phosphorylated by two cellular kinases, where PKC-zeta has the major and CKII the minor activities. In contrast, the P protein of another member of the morbillivirus genus, measles virus, is phosphorylated predominantly by CKII, whereas PKC-zeta has only minor activity. Selective inhibition of PKC-zeta activity within CV1 cells eliminated permissiveness to CDV replication, indicating an in vivo role for PKC-zeta in the virus replication cycle. The broad tissue expression of PKC-zeta parallels the pantropic nature of CDV infections, suggesting that PKC-zeta activity is a determinant of cellular permissiveness to CDV replication.

Animals↗
PubMed1997

Phosphorylated states of vesicular stomatitis virus P protein in vitro and in vivo.

We have previously shown that the phosphoprotein (P) of vesicular stomatitis virus (VSV), New Jersey serotype (PNJ) is phosphorylated by casein kinase II, within the N-terminal domain I (P1 form), whereas the C-terminal domain II is phosphorylated by a protein kinase activity associated with the L protein (P2 form) (D. J. Chattopadhyay and A.K. Banerjee, Cell 49, 407, 1987; A.M. Takacs et al., J. Virol. 66, 5842, 1992). In the present studies, we have mapped the corresponding P1 and P2 phosphorylation sites in the P protein of the well-studied Indiana serotype (PIND) and compared that with the two previously designated NS1 and NS2 forms present in vivo. The PIND expressed in Escherichia coli in an unphosphorylated form (P0) was used as substrate for recombinant casein kinase II (CKII). By site-directed mutagenesis, the CKII-mediated phosphorylation sites in the P protein were mapped at S60, T62, and S64 within the acidic domain I in vitro. In contrast, using BHK cell extract as the source of CKII or expressing P protein in COS cells labeled with 32PI, the phosphorylation sites were mapped at S60 and S64 with no phosphorylation at T62 residue. We used a peptide mapping technique by which the phosphorylation sites within domain I and domain II were determined. Using this method we demonstrated that the P1 and P2 forms are similar, if not identical, to the previously designated NS1 and NS2 forms, respectively. The domain II phosphorylating kinase activity, associated with the L protein, is shown to be present also in the N-RNA complex, indicating that this activity is of cellular origin. By site-directed mutagenesis, we have shown that S226 and S227 are involved in phosphorylation within domain II. We also demonstrate that the P1 and P2 forms are interconvertible and arise by phosphorylation/dephosphorylation of the phosphate groups in domain II, confirming the precursor-product relationship between the two phosphorylated forms of P protein.

Animals↗
PubMed1997

Fluorescein as a marker for subretinal transplantation of human fetal neural retina.

PURPOSE: To investigate the effect of fluorescein on human fetal neural retina and adult rat retina; and to use fluorescein to map the area of subretinal transplantation. METHODS: In vitro: Human fetal neural retina (8 to 14 weeks gestational age) was incubated in 0.03% fluorescein in Dulbecco's Modified Eagles Medium (DMEM) or DMEM alone for 30 min. Viability was determined using the trypan blue exclusion test, and results were compared. Effects of the fluorescein on cell morphology were assessed by observation of primary cultures for 1 week. In vivo: Human fetal neural retina was mechanically dissociated in 0.03% fluorescein in DMEM and transplanted to the subretinal space of immunosuppressed rats. To control for the effect of fluorescein on the grafted tissue, transplants were also performed in DMEM only. After transplantation, indirect ophthalmoscopy and true color fundus photography were performed to document the area covered by the transplant. One month after transplantation, the appearance of grafts exposed to fluorescein was compared to those that were not, at the light microscopic level. RESULTS: In vitro: Exposure of human fetal neural retina to fluorescein had no effect on viability. Similarly, in tissue culture, the fluorescein-exposed cells exhibited the same phenotype as the controls. In vivo: Immediately after transplantation the graft site was clearly outlined within the subretinal area and fluoresced intensely. There were no traces of the dye 2 h after transplantation. Cells that were transplanted with fluorescein survived transplantation, and one month after transplantation could be seen forming subretinal grafts. No differences were noted between these and control grafts. CONCLUSIONS: Fluorescein is an effective dye for immediate and transient localization of trans-scleral transplants to the subretinal space. It allows mapping of the area covered by the injection without interfering with the viability and differentiation of the transplanted cells. It allows unequivocal photo- and video-documentation in both the albino and pigmented fundi. It is already FDA approved for many other extra- and intraocular studies and now has directly been shown to be non-toxic to both human fetal neural retina and adult rodent retina.

Animals↗
PubMed1997

Fluorescent Gram stain in the microbiologic diagnosis of infectious keratitis and endophthalmitis.

PURPOSE: To verify the sensitivity of a recently described technique of fluorescent Gram stain (FGS) and evaluate its role in direct microscopic examination of clinical ocular samples. METHODS: In the first part of the study, culture suspensions of 10 bacterial isolates were stained, using FGS and conventional Gram stain (CGS), and were assessed for morphology, and Gram sign. In the second part, 39 corneal scrapings and 18 vitreous biopsy materials were stained and observed by both methods. RESULTS: Gram reaction and morphology of the bacteria, using CGS and FGS, were compared against culture. In both parts of the study, the sensitivity of CGS was significantly higher than FGS in the detection of Gram positive reaction (p = 0.01, 0.02). The specificities and predictive values of CGS and FGS were comparable in the evaluation of clinical samples. The bacterial morphology was demonstrated better (p = 0.01) with CGS. Significant quenching of fluorescence and change in Gram reaction with time were noted in FGS. CONCLUSIONS: The low sensitivity, quenching of fluorescence and change in Gram reaction presently preclude the usage of FGS as a diagnostic tool in ocular infections.

Endophthalmitis↗
PubMed1997

Major goat sperm 105 kDa maturation antigen: purification, characterization, and effect of its antiserum on acrosin activity.

A ConA binding membrane glycoantigen of 105 kDa molecular mass was purified from mature goat sperm by ion exchange and gel filtration chromatography. Of the detergents examined, the anionic deoxycholate was found to be highly effective in maximum solubilization of this sperm membrane antigen (SMA2). The analysis of the saccharide components by gas liquid chromatography revealed that the 105 kDa antigen (SMA2) contained the highest amount of mannose, followed by galactose and glucose in a ratio of 4:3:1. One amino sugar, N-acetylglucosamine, was also found to be present in the polysaccharide branching of the SMA2 antigen. The internal sulfydryl linkage is essential for the maintenance of the protein backbone of 105 kDa antigen. The antigen selectively resides on the anterior head of goat sperm. The binding of anti-SMA2 antibody to the integrated mature goat spermatozoa inhibited the release of acrosin after the induction of spermatozoa with Ca-ionophore.

Acetylglucosamine↗
PubMed1997

Phosphorylation within the amino-terminal acidic domain I of the phosphoprotein of vesicular stomatitis virus is required for transcription but not for replication.

Phosphorylation by casein kinase II at three specific residues (S-60, T-62, and S-64) within the acidic domain I of the P protein of Indiana serotype vesicular stomatitis virus has been shown to be critical for in vitro transcription activity of the viral RNA polymerase (P-L) complex. To examine the role of phosphorylation of P protein in transcription as well as replication in vivo, we used a panel of mutant P proteins in which the phosphate acceptor sites in domain I were substituted with alanines or other amino acids. Analyses of the alanine-substituted mutant P proteins for the ability to support defective interfering RNA replication in vivo suggest that phosphorylation of these residues does not play a significant role in the replicative function of the P protein since these mutant P proteins supported replication at levels > or = 70% of the wild-type P-protein level. However, the transcription function of most of the mutant proteins in vivo was severely impaired (2 to 10% of the wild-type P-protein level). The level of transcription supported by the mutant P protein (P(60/62/64)) in which all phosphate acceptor sites have been mutated to alanines was at best 2 to 3% of that of the wild-type P protein. Increasing the amount of P(60/62/64) expression in transfected cells did not rescue significant levels of transcription. Substitution with other amino acids at these sites had various effects on replication and transcription. While substitution with threonine residues (P(TTT)) had no apparent effect on transcription (113% of the wild-type level) or replication (81% of the wild-type level), substitution with phenylalanine (P(FFF)) rendered the protein much less active in transcription (< 5%). Substitution with arginine residues led to significantly reduced activity in replication (6%), whereas glutamic acid substituted P protein (P(EEE)) supported replication (42%) and transcription (86%) well. In addition, the mutant P proteins that were defective in replication (P(RRR)) or transcription (P(60/62/64)) did not behave as transdominant repressors of replication or transcription when coexpressed with wild-type P protein. From these results, we conclude that phosphorylation of domain I residues plays a major role in in vivo transcription activity of the P protein, whereas in vivo replicative function of the protein does not require phosphorylation. These findings support the contention that different phosphorylated states of the P protein regulate the transcriptase and replicase functions of the polymerase protein, L.

Amino Acid Substitution↗