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Biomedical subjects

S C Das

Publications and source records attributed to S C Das.

At least 19 recordsLinked to original sources
PubMed2002

Antibiotic resistance, virulence gene, and molecular profiles of Shiga toxin-producing Escherichia coli isolates from diverse sources in Calcutta, India.

Antibiotic resistance, virulence gene, and molecular profiles of Shiga toxin-producing Escherichia coli (STEC) non-O157 strains isolated from human stool samples, cow stool samples, and beef samples over a period of 2 years in Calcutta, India, were determined. Resistance to one or more antibiotics was observed in 49.2% of the STEC strains, with some of the strains exhibiting multidrug resistance. The dominant combinations of virulence genes present in the strains studied were stx(1) and stx(2) (44.5% of strains) and stx(1), stx(2), and hlyA (enterohemorrhagic E. coli hemolysin gene) (19% of strains). Only 6.4% of the STEC strains harbored eae. The diversity of STEC strains from various sources was assessed by random amplification of polymorphic DNA (RAPD). STEC strains that gave identical or nearly similar DNA fingerprints in RAPD-PCR and had similar virulence genotypes were further characterized by pulsed-field gel electrophoresis (PFGE). Identical RAPD and PFGE profiles were observed in four sets of strains, with each set comprising two strains. There was no match in the RAPD and PFGE profiles between strains of STEC isolated from cows and those isolated from humans. It appears that the clones present in bovine sources are not transmitted to humans in the Calcutta setting although these strains showed evolutionary relatedness. Maybe for this reason, STEC has still not become a major problem in India.

Animals↗
PubMed2001

Diclofenac sodium injection sterilized by autoclave and the occurrence of cyclic reaction producing a small amount of impurity.

A known impurity is formed in the production of a parenteral dosage form of diclofenac sodium if terminally sterilized by autoclave. This impurity has been detected as 1-(2,6-dichlorophenyl) indolin-2qone, which is also an intermediate from which diclofenac sodium is generally synthesized. It is only the condition of the autoclave method (i.e., 123 +/- 2 degrees C) that enforces the intramolecular cyclic reaction of diclofenac sodium forming the indolinone derivative and sodium hydroxide. The formation of this impurity has been found to depend on the initial pH of the formulation. The reaction follows first-order kinetics, and the energy of activation is 5.34 kcal/mol. The other excipients in the formulation do not have a role in this reaction. The concentration of the impurity in the resultant product in the ampule goes beyond the limit of the raw materials in the pharmacopoeias. It is thus preferable to use an alternative sterilization method; that is, an aseptic filtration method in which the formation of this impurity can be avoided.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

Comparative evaluation of hydrophobicity measures for virulence determination of Staphylococcus epidermidis from hospitalized patients & healthy individuals.

BACKGROUND & OBJECTIVES: Hydrophobicity is one of the recognized markers for identifying pathogenic strains of Staphylococcus epidermidis. A number of tests are available for measuring the hydrophobic character but three tests viz., salt aggregation test (SAT), n-hexadecane adherence assay (HAA) and xylene adherence assay (XAA) are in common practice with different degrees of sensitivity. However, in the Indian context, no systematic study has been reported on the hydrophobicity of S. epidermidis. Hence, the present study was undertaken to compare the three methods for hydrophobicity measurement for identifying the pathogenic isolates of S. epidermidis. METHODS: Of the 597 samples obtained from milker's and butcher's (hand and nose), hospitalized pre-operative patients (hand, nose, ear), and post-operative patients (blood) examined, 212 isolates of S. epidermidis were recovered using established laboratory procedures. The isolates were screened by the three tests viz., SAT, HAA and XAA. The identified hydrophobic isolates were further tested by mouse inoculation method. RESULTS: Of the 212 S. epidermidis isolates studied, 24 (11.32%), 23 (10.84%) and 4 (1.88%) were found to be hydrophobic as detected by HAA, XAA and SAT, respectively. No isolates from apparently healthy individuals were found to be hydrophobic by SAT while 13 (8.76%) and 10 (8.24%) strains from apparently healthy individuals were detected to be hydrophobic by HAA and XAA, respectively. Seven (33.38%) isolates each were hydrophobic by HAA and XAA and 4 (22.22%) by SAT among the isolates from hospitalized post-operative patients. INTERPRETATION & CONCLUSION: The results suggested that there was no difference in the number of strains detected as hydrophobic by HAA and XAA, and any of the two tests may be used for screening the hydrophobic strains of S. epidermidis from healthy individuals and patients.

Bacteriological Techniques↗
PubMed2000

Chemical, pathological and toxicological studies of the effects of RICOM-1013-J of Ricinus communis var minor on women volunteers and rodents.

RICOM-1013-J (Ricinus communis var minor) administered orally once to each of 12 women volunteers at a dose of 2.5-2.7 g per 8 months, protected against pregnancy over a period of 7-8 months of study. A study of the effect of a contraceptive dose (20 mg/kg) on metabolic parameters in rat (food and water in-take, urine and faecal output and body weight) over a period of 4 months showed a slight decrease in all the parameters in the first 1-8 weeks. This effect was reversible attaining pretreatment levels from week 16. The LD(50) in an acute toxicity test in mice was 63.1 +/- 16.0 g/kg s.c. Determination of blood urea, sodium (Na(+)), potassium (K(+)), chloride (Cl(-)) and bicarbonate (HCO$_¿3¿ ¿-¿$)as a measure of renal function and alkaline phosphatase (ALP), transaminases (GPT and GOT) and transpeptidases (GGT) as a measure of liver function showed that liver function profiles in pretreated rats were not significantly different from control (p < 0.05) on day 21 to day 150. However, serum levels of ALP and GGT at day 120 to day 150 were moderately but significantly elevated (p > 0.05) compared with the control. There were no significant changes in renal function profiles in pretreated rats (p < 0.05) compared with the control. The results of the liver and renal function profiles in women volunteers showed that there were no significant (p < 0.05) changes in renal functions on day 206 following RICOM-1013-J administration. However, serum levels of ALP and GGT showed a slight rise in about 70% of volunteers, whereas bilirubin and transaminases levels were normal. The present results indicate a very high efficacy and margin of safety of RICOM-1013-J in women volunteers. The increase in ALP and GGT in both animal and women volunteers suggest mild intrahepatic cholestatic changes which may be attributed to an oestrogenic effect of RICOM-1013-J.

Adult↗
PubMed2000

Preliminary clinical investigation of the contraceptive efficacy and chemical pathological effects of RICOM-1013-J of Ricinus communis var minor on women volunteers.

The seeds of Ricinus communis Linn, RICOM-1013-J, administered as a single oral dose of 2.3-2.5 g once per 12 months protected against pregnancy in 50 women volunteers for a period of one year. The antifertility and contraceptive efficacy of the seed was demonstrated in this study. Clinical observation revealed very minimal side effects. Some of the side effects investigated included headache, nausea, vomiting, weight gain, loss of appetite, raised blood pressure and dysmenorrhoea. Furthermore, both the renal and liver functions were not affected as revealed by urea, electrolyte and creatinine values as well as total bilirubin, conjugated bilirubin, serum albumin, total protein and transaminases values when compared with control values. In addition cholesterol and phospholipids were not significantly altered. When all these results are considered together, it seems unlikely that the antifertility and contraceptive efficacy of RICOM-1013-J is due to hormonal mechanisms alone since side effects, renal and liver function, and cholesterol effects attributable to oestrogen and/or progesterone were minimal in the volunteers.

Cholesterol↗
PubMed2000

Improved technique for transient expression and negative strand virus rescue using fowlpox T7 recombinant virus in mammalian cells.

The suitability of recombinant T7 polymerase produced using either the highly attenuated MVA strain of vaccinia (MVA-T7) or fowlpox virus (FP-T7) for transient expression and negative strand virus rescue was compared in two mammalian cell lines (MDBK and Vero) and in primary cells of bovine, ovine and caprine origin. Such primary cells are more permissive for the growth of wild type strains of morbilliviruses, such as Rinderpest virus and Peste des petits ruminants virus. MVA-T7 was found to be highly cytopathic in the primary cells, multiplying rapidly and killing the cells within 3-5 days of infection, even when very low multiplicities of infection (MOI) were used. In contrast, FP-T7, which appeared to express similar amounts of T7 polymerase, was found to be non-cytopathic in a variety of primary and established cell lines of mammalian origin and was suitable for use in virus rescue experiments. MDBK cells and primary cells, unlike Vero cells, could not be efficiently transfected and so were unsuitable for virus rescue. Optimal conditions for rinderpest virus rescue in Vero cells were established using FP-T7 in place of MVA-T7. This system will be suitable for rescuing other viruses which grow in Vero cells.

Animals↗
PubMed2000

Recovery and characterization of a chimeric rinderpest virus with the glycoproteins of peste-des-petits-ruminants virus: homologous F and H proteins are required for virus viability.

Rinderpest (RP) and peste-des-petits-ruminants (PPR) are two important diseases of domestic ruminants. To improve on currently available vaccines against PPR, we have created cDNA copies of the RP virus genome in which either the fusion (F) or hemagglutinin (H) gene, or both, was replaced with the corresponding gene from PPR virus. It was necessary to develop a modified rescue system in which the T7 RNA polymerase was provided by a recombinant fowlpox virus and the entire rescue procedure took place in Vero cells before we could obtain live virus from these chimeric constructs. No virus was recovered when only one of the glycoprotein genes was changed, but a chimeric virus containing both F and H genes from PPR virus was reproducibly rescued from cDNA, indicating that a virus-specific functional interaction takes place between the F and H proteins. The rescued virus expressing the PPR glycoproteins grew more slowly in tissue culture than either parental virus and formed abnormally large syncytia. Goats infected with the chimera showed no adverse reaction, as assessed by clinical signs, temperature, leukocyte count, virus isolation, and serology, and were protected from subsequent challenge with wild-type PPR virus.

Animals↗
PubMed1999

Field evaluation of herbal mosquito repellents.

Repellent properties of Zanthoxylum armatum DC. Syn. Z. alatum Roxb. (Timur), Curcuma aromatica (Jungli haldi) and Azadirachta indica (Neem) oils were evaluated against mosquitoes in mustard (Brassica sp.) and coconut (Cocos sp.) oil base and compared with synthetic repellent. Dimethyl phthalate (DMP) as standard. Timur and jungli haldi afforded better protection in the both the base at all the concentrations. Tepellents in mustard oil gave longer protection time than those in coconut oil. At 0.57 mg/cm2 concentration timur oil gave significantly higher protection both in mustard (445 min) as well as coconut oil (404 min) than the other repellents and DMP.

Humans↗
PubMed1997

Role of Anopheles culicifacies during an outbreak of malaria in Gorubandha P.H.C., Assam.

Entomological investigation during an outbreak of malaria in Gorubandha PHC in Sonitpur district revealed unusually high density of Anopheles culicifacies followed by An.minimus. Parity rates of both the species were very high, 65% and 62.2% respectively. An. culicifacies was incriminated as malaria vector. Sporozoite rate recorded was 0.63%. Both the species were found susceptible to DDT. This substantiates the epidemiological observation which yielded 98% Plasmodium falciparum malaria out of 35.2% malaria positive cases. Incrimination of An. culicifacies means adding one more malaria vector to this region.

Animals↗
PubMed1996

Evaluation of Methoprene (Altosid) and Diflubenzuron (Dimilin) for control of mosquito breeding in Tezpur (Assam).

Insect growth regulators (IGRs) namely, Isopropyl (E-E)-(RS)-11-methoxy-3,7,11-trimethyldodeca-2, 4-dinoate (Methoprene) and 1-(4-cyclophenyl)-3-(2,6-diflerobenzoyl) urea (Diflubenzuron) were evaluated against mosquito larvae in laboratory as well as in different breeding habitats in Tezpur, Assam. LC90 values of diflubenzuron against Culex quinquefasciatus and Aedes albopictus were 0.0022 and 0.0027 ppm respectively, while it was 0.0027 and 0.0022 ppm respectively in case of methoprene. However, LC50 values of both the IGRs were almost same in case of Ae. albopictus and Cx. quinquefasciatus (varies between 0.0009 and 0.0011 ppm). In case of methoprene, maximum mortality was observed in pupal stage though the exposure was given in all the cases to the III instar larvae. Field trials were conducted in cemented drains, small ponds and ditches. At 0.2 ppm (0.020 kg/ha) both diflubenzuron and methoprene were found to eliminate 92-96 per cent Culex and Anopheles larvae. Methoprene and diflubenzuron were found equally effective for control of mosquito breeding in different breeding habitats and provide better efficacy than conventional larvicides and biocides.

Aedes↗
PubMed1995

Endemic goiter in the Jos Plateau region of northern Nigeria.

This study is an endemic goiter survey of 3476 school children in 13 Local Government Councils (LGCs) and 1004 subjects in a whole community of one LGC, Plateau State, Northern Nigeria, to determine the prevalence of goiter as well as to identify some of the etiological agents involved. Results of the survey showed that the disease is highly endemic in the area with prevalence varying in places from 1 to 23% of these subjects. Females showed a markedly higher prevalence of goiter. Analysis of 729 urine samples indicated that iodine excretion ranged from 3.5 to 1.3 microgram/dl (32-154 microgram/g creatinine) and was similar to that in iodine deficient areas in the world, but no relation was observed between the prevalence of goiter and urinary iodine. Urinary thiocyanate levels were less than 0.5 mg/dl, suggesting that the role of the thiocyanate as a goitrogen is not important in the region. Thyroid hormone parameters in village subjects with goiter were similar to those in goiter endemia except serum thyroxine (T4). An interesting result found in village subjects was very high serum thyroxine binding globulin, which leads to an increase in serum T4. This study indicated that Northern Nigeria is an area of endemic goiter. Although some areas in Plateau State are iodine deficient zones, we could not conclude that the etiology of endemic goiter in this area is associated with iodine deficiency. There may be an interplay of multiple factors of etiological importance.

Adolescent↗
PubMed1994

Thyroid function profile and differential serum lipid and lipoproteins in Africans with endemic goitre.

Serum total thyroxine (TT4), total triiodothyronine (TT3), thyrotrophine (TSH), thyroxine binding globulin (TBG), total lipids, triglycerides, total cholesterol, beta lipoprotein and beta lipoprotein cholesterol level were measured in 68 goitrous subjects and 4 agoitrous cretins by the techniques based on enzyme immunoassay (ELISA) (for thyroid parameters) and enzyme substrate principle (for lipid and lipoproteins) using commercial test kits (Boehringer Mannheim, W. Germany) and the results were matched with those derived from 59 clinically normal control subjects. The mean values of serum TT3, TBG, TSH and T3/T4 ratio showed positive correlations with the goitre size (r > 0.8, P < 0.005) while mean serum TT4 was negatively correlated (r > -0.9, P < 0.005). Typical biochemical features of hypothyroidism on serum lipid and lipoprotein profile were seen throughout, the changes being more marked in cretins. However, the serum lipid and lipoproteins were also, to some extent, found to be positively related to the thyroid size. In addition, a number of patients also showed variations in the serum lipid and lipoprotein levels appropriate to their compensated thyroid functional status in endemic goitre (as reflected by low TT4, raised TT3 and raised T3/T4 quotients).

Adolescent↗
PubMed1994

Immunogenic activity of viral polypeptides of an Indian isolate of infectious bursal disease virus.

An Indian isolate of infectious bursal disease virus, i.e. IBDV-P/AD/81, was analysed for immunogenic activity of its structural polypeptides. Virus was purified from infected bursal homogenate by sucrose density gradient centrifugation. It showed five different structural polypeptides of 75.8, 45, 40.7, 33.1 and 27 kDa molecular weights in sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Anti infectious bursal disease virus (IBDV) antibodies were tested using enzyme-linked immunosorbent assay (ELISA) and neutralization test (NT). Polypeptide 40.7 kDa (VP2) was known to have neutralizing epitopes. However, polyclonal anti VP2 failed to neutralize the virus. It was interpreted that VP2 had labile neutralizing epitopes which get altered confirmationally by SDS. Surprisingly, polyclonal anti 33.1 kDa (VP3) had mild neutralizing activity.

Animals↗
PubMed1994

Laboratory and field evaluation of Bacillus thuringiensis and B. sphaericus against mosquito larvae.

Laboratory and field trials were carried out with two formulations of Bacillus thuringiensis and four strains of Bacillus sphaericus (B 42, B 64, B 87 and B 33) against mosquito larvae in different breeding habitats of Tezpur, Assam. LC90 of B. thuringiensis var israelensis (formulation Teknar) against Ae. albopictus, Cx. quinquefasciatus and Cx. gelidus were recorded as 0.443, 0.453 and 2.15 ppm respectively and LC90 of B. thuringiensis (Deltox: VCRC B-17) against Ae. albopictus, Cx. quinquefasciatus, Cx. gelidus and Cx. malayi were 8.414, 11.22, 5.24 and 6.761 ppm respectively. LC90 of B. sphaericus strains B 42, B 64, B 87 and B 33 against Cx. quinquefasciatus were 0.055, 0.115, 0.046 and 0.257 ppm respectively. At the dosage of 1 l/ha 87 per cent mortality was achieved after 24 hrs with Bti and it increased to 90-95 per cent at 1.5 l/ha. In polluted cemented drains 93-97 per cent kill of Cx. quinquefasciatus was observed at 2.5 l/ha. Out of four strains of B. sphaericus evaluated, strain B 87 was found to be the most effective as 87-96 per cent kill was achieved with only 0.1 kg/ha for Cx. quinquefasciatus, Cx. vishnui and A. vagus. For others 0.2 kg/ha dosage, eliminated 96-100 per cent Cx. vishnui gr. for B 42, 92-93 per cent for B 64 and 90-93 per cent for B 33 strain.

Aedes↗