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Biomedical subjects

S Garg

Publications and source records attributed to S Garg.

At least 73 records · Page 4Linked to original sources
PubMed1995

Biotype traits and antibiotic susceptibility of Vibrio cholerae serogroup O1 before, during and after the emergence of the O139 serogroup.

Sixty-nine strains of Vibrio cholerae O1 isolated at different times were analysed to investigate if there were any differences among the O1 strains isolated before, during and after the advent of the O139 serogroup. Of the 69 O1 strains examined, 68 belonged to the Ogawa serotype while one belonged to the Inaba serotype. With the exception of one strain all other strains of V. cholerae O1 belonged to the eltor biotype. A single O1 strain isolated before the emergence of the O139 serogroup could not be classified as either eltor or classical biotype because it was resistant to both classical and eltor specific bacteriophages. Marked variations in the susceptibility to antibiotics of V. cholerae O1 isolated during the different periods were observed. In addition, strains of V. cholerae isolated after the epidemic of serogroup O139 in Calcutta showed an expanding R-type with resistance to a variety of drugs as compared to the O1 strains isolated before the advent of the O139 serogroup. From this study, it is clear that there is a substantial mobility in genetic elements of V. cholerae O1 which necessitates a continuous monitoring to keep abreast of the changing traits of the etiologic agent of cholera.

Agglutination Tests↗
PubMed1995

Development and testing of monoclonal antibody-based rapid immunodiagnostic test kits for direct detection of Vibrio cholerae O139 synonym Bengal.

We report on the development and testing of two monoclonal antibody-based rapid immunodiagnostic test kits, BengalScreen, a coagglutination test, and Bengal DFA, a direct fluorescent-antibody test, for direct detection of Vibrio cholerae O139 synonym Bengal in clinical and environmental specimens. The BengalScreen test requires less than 5 min to complete and can be used in the field. Bengal DFA, being more sensitive than BengalScreen, requires only one reagent and less than 20 min for detection and enumeration of V. cholerae O139 synonym Bengal. In tests for specificity, all 40 strains of V. cholerae O139 reacted with both test kits, whereas 157 strains of heterologous species examined did not, yielding 100% specificity in this study. A field trial was conducted in with both BengalScreen and Bengal DFA, and the results were compared with those obtained by conventional culture methods. BengalScreen demonstrated a sensitivity of 95%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 94%. Results obtained by Bengal DFA, on the other hand, were 100% sensitive and 100% specific and yielded 100% positive and negative predictive values compared with culture methods. In a second evaluation, 93 stool specimens from Mexico that were negative for V. cholerae O139 by culture were also tested with both the BengalScreen and Bengal DFA kits. None of the 93 specimens were positive for V. cholerae O139 by both tests. A concentration method was optimized for screening of environmental water samples for V. cholerae O139 synonym Bengal with rapid test kits. BengalScreen results were unequivocally positive when water samples contained at least 2.0 x 10(3) CFU/ml, whereas Bengal DFA demonstrated an unequivocally positive reaction when the water sample contained at least 1.5 x 10(2) CFU/ml. When Bengal DFA was compared with conventional culture methods for enumeration of V. cholerae O139 synonym Bengal organisms, no difference was observed.

Agglutination Tests↗
PubMed1995

Monoclonal antibodies against Ogawa specific & Ogawa-Inaba common antigenic determinants of Vibrio cholerae O1 & their diagnostic utility.

Monoclonal antibodies to Ogawa-Inaba common antigenic determinant and Ogawa specific antigenic determinant of V. cholerae belonging to the serogroup O1 were generated from BALB/c mice immunized with V. cholerae O1 Eltor Ogawa strain. Reactivity and specificities of the monoclonal antibodies were examined by slide agglutination method. The monoclonal antibodies agglutinated all the V. cholerae O1 strains tested but did not agglutinate with any of the other currently recognized 140 serogroups of V. cholerae non-O1 as well as with a variety of other enteric pathogens. Diagnostic utility of the MAbs produced in this study as compared to polyclonal O1 and monospecific antisera showed that the MAbs were as good as the latter for serological diagnosis of the two serotypes of V. cholerae O1.

Antibodies, Monoclonal↗
PubMed1995

Safety of intrauterine administration of purified neem seed oil (Praneem Vilci) in women & effect of its co-administration with the heterospecies dimer birth control vaccine on antibody response to human chorionic gonadotropin.

Praneem Vilci (PV), purified neem oil was reported to exercise a reversible antifertility effect after a single intrauterine instillation in rodents and primates without any adverse effects. After toxicology, drug regulatory and ethical clearances, a phase I clinical trial was conducted on PV. Eighteen healthy tubectomised women were enrolled to evaluate the safety of a single intrauterine instillation of PV and to determine the effect of its co-administration on anti-hCG response to the heterospecies dimer (HSD) hCG vaccine. Eight women received PV alone and ten women were given the HSD-hCG vaccine in addition. Base-line and post-treatment haematological and biochemical profiles were determined as also the mid-luteal serum progesterone. Endometrial biopsies were examined to assess ovulatory status and the effect of intrauterine treatment with PV on the endometrium. Anti-hCG antibody titres were estimated in women who were concurrently immunized with the HSD vaccine. No untoward reaction was observed in any woman. Menstrual pattern and ovulatory status remained unaltered. Endometrial biopsy after PV instillation in one woman showed non-specific endometritis but she remained asymptomatic. Mild eosinophilia was seen in two women and this reverted to normal on its own. All women receiving PV and the HSD vaccine generated antibodies against hCG. Our data show that intrauterine administration of PV is safe and does not prevent the antibody response to HSD-hCG vaccine.

Adult↗
PubMed1994

Synergistic spermicidal activity of neem seed extract, reetha saponins and quinine hydrochloride.

In order to identify potent spermicidal agents which are free from the side effects of currently available agents, spermicidal activity of purified neem seeds extract (Praneem), reetha saponins and quinine hydrochloride was studied individually and in combination. Sander-Cramer test was used to assess the activity on human sperm. Under the test conditions, minimum effective spermicidal concentrations for Praneem, reetha saponins and quinine hydrochloride were 25%, 0.05% and 0.346%, respectively. At these concentrations, 100% of the sperm were immobilised within 20 seconds. A positive synergistic effect in the spermicidal activity of these components, if used in combination, was observed which implies the use of reduced concentrations of each to bring about the desired action. The selected combination formulated into a suitable dosage form is likely to offer dual benefit of a potent contraceptive and an antimicrobial preparation.

Drug Combinations↗
PubMed1994

Comparison of extraction procedures on the immunocontraceptive activity of neem seed extracts.

Azadirachta indica (Neem) seed extracts are known to activate the local cell-mediated immune reactions after a single intrauterine administration, leading to a long term reversible block of fertility. In order to identify and characterize the active fraction responsible for this activity, neem seeds were extracted by both mechanical expression and solvent extraction using a range of polar to non-polar solvents which yielded 3 broad fractions. The mechanically expressed oil was fractionated using different approaches and studied for antifertility activity. The hexane extract and a corresponding column fraction showed potent and reproducible antifertility activity. Other fractions were less stable with regard to reproducibility of effects and composition. It is our conclusion that for subsequent fractionation to reach the last active fraction, the hexane extract is the most useful starting material.

Animals↗
PubMed1994

Synthesis and preliminary evaluation of para- and meta-[18F]fluorobenzylguanidine.

meta-[18F]Fluorobenzylguanidine ([18F]MFBG) and para-[18F]fluorobenzylguanidine ([18F]PFBG) were synthesized in three steps beginning with a fluoro for nitro exchange reaction on 3- and 4-nitrobenzonitrile, respectively. Overall radiochemical yields were 10-15% for [18F]MFBG and 50-55% for [18F]PFBG in a total synthesis time of 60 min. However, impurities interfered with the binding of the product to target cells. A new route was adopted for the synthesis of [18F]PFBG using 4-nitrilophenyl trimethylammonium trifluoromethanesulfonate (Q.S.) as the starting material. In addition to shortening the overall synthesis time by 10 min, this precursor also eliminated problems associated with the presence of small amounts of starting material in the preparation. In vitro binding of [18F]PFBG prepared by the Q.S. method to SK-N-SH, human neuroblastoma cells was 26.5 +/- 1.1%, compared to 16.9 +/- 1.6% when the nitro precursor was used. Selective uptake of both 18F-labeled isomers in the heart and adrenal was seen in mice. At 4 h, adrenal and heart uptake of [18F]PFBG prepared using Q.S. was 20.3 +/- 4.8 and 5.9 +/- 0.8% ID/g respectively, compared to 23.8 +/- 5.0 and 10.5 +/- 1.7% ID/g for [18F]MFBG. Based on the 5-fold higher radiochemical yields obtained with [18F]PFBG, this isomer would appear to be the more practical choice; however, in vitro and in vivo results suggest that [18F]MFBG exhibits greater similarities to MIBG.

Animals↗
PubMed1994

Spread of Vibrio cholerae O139 Bengal in India.

Vibrio cholerae serogroup O139 Bengal, a novel strain with epidemic potential, completely displaced V. cholerae serogroup 01 in Calcutta in January 1993, which was followed by an epidemic caused by V. cholerae O139 in March-May 1993. From November 1992 to July 1993, 95.6% of 916 V. cholerae isolates submitted to the National Institute of Cholera and Enteric Diseases from 28 locations in India were confirmed as serogroup O139. As of July 1993, V. cholerae O139 had been isolated from 13 Indian states and a union territory, and large outbreaks of cholera caused by the O139 serogroup had occurred in several cities. The extent of spread of V. cholerae O139 Bengal in India and its ability to swiftly disseminate leaves little doubt that this is the beginning of the eighth pandemic of cholera.

Adolescent↗
PubMed1994

Production and cross-reactivity patterns of a panel of high affinity monoclonal antibodies to Vibrio cholerae O139 Bengal.

A series of monoclonal antibodies of different isotypes specific for Vibrio cholerae O139, the new pandemic strain of cholera, was produced. These mAbs reacted only with the reference strain (MO45) representing serovar O139 but did not react with any of the other reference strains representing serovars O1 to O140. Significantly, the mAbs did not agglutinate the R-cultures of V. cholerae (CA385, 20-93) which demonstrated the exceptional specificity of these mAbs and indicated that the mAbs recognized antigenic determinants unique for the O139 serovar. There was heterogeneity in the intensity of reactivity of the mAbs with strains of V. cholerae O139 isolated from diverse sources. Apart from 4H6, the other mAbs agglutinated all the O139 strains examined. 2D12 and 2F8 were the best mAbs based on the intensity of agglutination with all the O139 strains. Evaluation of 3A10 in comparison with a polyclonal anti-O139 antibody raised in rabbit using the slide agglutination format revealed that 3A10 fared as well as the polyclonal antibody for the laboratory identification of the O139 serovar. The acquisition of these mAbs provide reagents which would be very useful in the development of simple immunodiagnostic assays for the diagnosis of V. cholerae O139 infections.

Agglutination Tests↗
PubMed1994

Characterization of phenotypic, serological, and toxigenic traits of Vibrio cholerae O139 bengal.

Biochemical and physiological traits of a collection of strains of Vibrio cholerae O139 Bengal isolated from India, Bangladesh, and Thailand showed that these strains formed a phenotypically homogeneous group with identical characteristics that were essentially similar to those of the O1 serogroup. Resistance to 150 micrograms of the vibriostatic agent O/129 (2,4-diamino-6,7-diisopropylpteridine) and Mukherjee's El Tor phage 5 and classical phage IV and the nonagglutinability of the strains with O1 antiserum were the only discernible differences between the O139 and O1 serogroups. Extensive serological characterization further revealed the O139 serogroup to be distinct from the existing 138 serogroups of V. cholerae. Antiserum raised against the O139 serogroup required absorption with the R reference strain CA385 and with the reference strain representing serogroup O22 to remove cross-reacting agglutinins. All of the 223 representative strains of V. cholerae O139 examined hybridized with DNA probes specific for the cholera toxin (CT) gene, zonula occludens toxin gene, and El Tor hemolysin gene but not with the probe specific for the heat-stable enterotoxin gene. The amount of CT present in stool samples of patients infected with the O139 serogroup was higher than that found in stools of patients infected with O1 El Tor, and this echoed findings that the amount of CT produced by O139 strains in vitro was higher than that produced by the O1 El Tor strains. The nucleotide sequences of the genes encoding the A and B subunits of CT of the O139 serogroup were identical to the sequences reported for the CT gene of O1 El Tor. The CT gene of O139 strains could be amplified by using primers developed for detection of the CT gene of the O1 serogroup by a PCR assay, which could also be used to detect the CT gene in stool samples of patients infected with strains of the O139 serogroup.

Animals↗
PubMed1994

Vibrio cholerae O139 in Calcutta.

Vibrio cholerae O139 was recovered from 28 of 79 children with acute watery diarrhoea. Clinically, they presented with watery diarrhoea (100%), vomiting (79%), abdominal cramps (61%), anorexia (61%), dehydration (100%), and absence of fever. Both clinical and blood biochemical parameters of these cases were similar to the illness caused by the new strain in adults. Hypoglycaemia was seen in 40% of those screened.

Acute Disease↗
PubMed1994

Outbreak of cholera due to Vibrio cholerae 01 in Orissa state.

During May-June 1993, an outbreak of acute diarrhoea resulting in deaths primarily in adults was reported in two districts of Orissa state. Epidemiological and microbiological investigations revealed that this outbreak was caused by V. cholerae 01 biotype EITor. V. cholerae 01 strains were uniformly resistant to furazolidone.

Adult↗
PubMed1994

PET imaging of osteosarcoma in dogs using a fluorine-18-labeled monoclonal antibody Fab fragment.

UNLABELLED: Four dogs with histologically confirmed osteogenic sarcoma were studied with PET following intravenous injection of the 18F-labeled Fab fragment of TP-3, a monoclonal antibody specific for human and canine osteosarcomas. METHODS: The antibody fragment was labeled using the N-succinimidyl 8-[(4'-[18F]fluorobenzyl)amino]suberate acylation agent. Blood clearance of activity was biphasic in all dogs but half-times were variable (T1/2 beta = 2-13 hr). Catabolism of labeled Fab was reflected by the decrease in protein-associated activity in serum from more than 90% at 1 min to 60%-80% at 4 hr. RESULTS: PET images demonstrated increased accumulation of 18F at the primary tumor site relative to normal contralateral bone in one dog as early as 15 min after injection. Biopsies obtained after euthanasia indicated higher uptake at the edges of the tumor as observed on the PET scans. Tumor uptake was 1-3 x 10(-3)% injected dose/g, a level similar to that reported for other Fab fragments in human tumors. In the three dogs with metastatic disease, early PET images reflected activity in the blood pool but later uptake was observed in suspected metastatic sites. CONCLUSIONS: These results, although preliminary, suggest that PET imaging of 18F-labeled antibody fragments is feasible and that dogs with spontaneous tumors could be a valuable model for preclinical research with radioimmunoconjugates.

Animals↗
PubMed1993

Engineering Fab' fragments for efficient F(ab)2 formation in Escherichia coli and for improved in vivo stability.

We previously developed an efficient route to humanized F(ab')2 fragments by high level secretion of the Fab' arms from Escherichia coli followed by directed chemical coupling in vitro. Here the number and type of interchain linkages in F(ab')2 molecules has been modified to simplify their production and improve their serum stability. All F(ab')2 variants had comparable binding affinity for the p185HER2 Ag and antiproliferative activity against p185HER2-overexpressing tumor cells. This was anticipated since the modifications are distant from the Ag-binding loops. Replacement of a single disulfide bridge between Fab' arms with a more stable thioether bridge increased the serum permanence time in normal mice by threefold to 2.1 h. Removal of the disulfide bond between L and H chains in the thioether-bridged F(ab')2 did not affect the pharmacokinetics, suggesting that the L chain remains associated with the H chain. An additional Fab' variant containing three repeats of the motif, CysProPro, was constructed with the aim of promoting efficient formation of F(ab')2 in E. coli. This Fab' (CPP)3 variant was recovered predominantly (up to 70%) as F(ab')2 directly from fermentation cell pastes, thus circumventing the need for in vitro coupling. The F(ab')2 (CPP)3 variant has a similar serum pharmacokinetics to the thioether-bridged molecules. The improvements described here for deriving F(ab')2 fragments from E. coli should enhance the clinical potential of these molecules.

Amino Acid Sequence↗