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Biomedical subjects

V Singh

Publications and source records attributed to V Singh.

At least 19 recordsLinked to original sources
PubMed1992

Identification of infection of an Australian resident with the human immunodeficiency virus type 2 (HIV-2).

OBJECTIVE: To present the first confirmed case of human immunodeficiency virus infection type 2 (HIV-2) in an Australian resident. CLINICAL FEATURES: HIV-2 infection in a west African man resident in Sydney was diagnosed in 1992 at Westmead Hospital, Sydney, by serological testing. He was asymptomatic and the blood CD4 T-lymphocyte concentration was not significantly reduced. Infection was probably acquired before migration to Australia. The patient was initially tested for HIV-1 antibody as part of an application for permanent residency. He was in no obvious risk group or transmission category. His serum was repeatedly positive by Genetic Systems enzyme immunoassay (EIA) and borderline by Abbott EIA, was reactive to the HIV-2 peptide on a synthetic envelope peptide assay, and was strongly reactive to all HIV-2 specific viral protein bands on an HIV-2 western blot test. HIV-2 was isolated by co-cultivation of the patient's peripheral blood mononuclear cells and identified by hybridisation using HIV-2 specific oligonucleotide probes, with further confirmation by polymerase chain reaction. INTERVENTION AND OUTCOME: The patient was counselled regarding the clinical course and prognosis of HIV-2 infection, the possible indications for zidovudine therapy, modes of transmission of the virus and safer sex precautions. CONCLUSIONS: This is the first documented case of HIV-2 infection diagnosed in Australia and raises the possibility of other undetected cases. The cost effectiveness of general testing for HIV-2 needs to be assessed and formal epidemiological sentinel programs should be established to monitor specific Australian populations.

AIDS Serodiagnosis↗
PubMed1992

Design of liposome to improve encapsulation efficiency of gelonin and its effect on immunoreactivity and ribosome inactivating property.

Gelonin, purified from the seeds of Gelonium multiflorum, using cation-exchange and gel-filtration chromatography was characterised for its purity, homogeneity and molecular weight by reverse-phase HPLC (RP-HPLC) and SDS-PAGE analysis. The HPLC purified gelonin was used for entrapment studies in the liposomes. Liposomes were prepared by reverse phase evaporation (REV) technique using three different types of lipid composition in the same molar ratio. The method resulted in 75-80% entrapment efficiency of gelonin in the liposomes. Entrapped and unentrapped gelonin was characterized for physico-chemical, immunochemical and biological properties. The immunoreactivity of entrapped gelonin was fully preserved but the ribosome-inactivating property was slightly inhibited. The method involved mild conditions, highly reproducible and the liposomes produced appeared to be stable for several months. It has important implications in the development of cell type specific cytotoxic agents where a chemical cross-linking is involved which significantly inhibits both immunoreactivity and ribosome-inactivating ability of the toxin.

Cell-Free System↗
PubMed1992

Screening for cervical cancer by direct inspection.

OBJECTIVE: To assess the efficacy of visual screening for cervical cancer in the maternal and child health setting. DESIGN: Clinical and cytological screening. SETTING: Maternal and child health centres, Delhi. SUBJECTS: 44,970 women attending the centres from May 1988 to March 1991. RESULTS: 238 cancers in early stages (0-IIa) were detected cytologically and proved through biopsy. Prevalence of cancer in women defined as high risk through examination by speculum was 29/1000 as compared to 1.53/1000 among women with a normal looking cervix. Though only 11.4% women belonged to the high risk category, 63% had early stage cancer. If all women with bleeding symptoms were included in the high risk category, the yield of cancer would be 71.4% (170/238) by referring only 15.6% of women attending maternal and child health centres for further evaluation through cytology or colposcopy. CONCLUSION: Though visual screening is a suboptimal strategy in comparison to the cytological screening, it may be useful where there is a heavy load of prevalent cancer and where cytological screening may not be available for years to come.

Biopsy↗
PubMed1992

A high frequency of human papillomavirus DNA sequences in cervical carcinomas of Indian women as revealed by Southern blot hybridization and polymerase chain reaction.

Ninety-six colposcopically directed biopsies from squamous epithelial carcinoma of the uterine cervix and 22 age-matched normal control biopsy specimens were examined by both Southern blot hybridization and polymerase chain reaction (PCR) for the presence of different human papillomavirus (HPV) DNA types. Cancer of the uterine cervix, which is the most common malignant disease in Indian women, showed a high frequency (98%) of HPV as compared to those reported from other parts of the world. HPV type 16 was found to be the dominant (64%) type while the frequency of HPV type 18 was very low (3%). On individual typing of HPV, no biopsy was found to contain any other known HPV types under stringent conditions of hybridization except a single case of HPV type 11. Only one case of double infection with HPV types 16 and 18 was recorded. Under low stringency conditions of hybridization with a mixed probe of HPV types 16 and 18, 29 additional biopsies were found to be positive. Southern blot hybridization alone detected HPV DNA in 92% of the cases but none in the controls. By PCR, six (6.25%) more cases and four (18.18%) healthy women were found to be positive for HPVs. Analysis of the physical state of HPV 16 indicated integration in about 70% of carcinoma cases while 30% of them were in episomal form. The findings suggest that infection with HPV is an important etiologic factor for the development of cervical cancer, that a number of such tumours may arise without HPV infection, and that integration of the viral DNA into host genome is not always essential for malignant progression.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

HSV-IgA serum antibodies in cervical intraepithelial neoplasia and invasive cancer patients, and in their spouses: a case control study.

Class-specific IgG and IgA antibodies to HSV were assayed in women with CIN (76), invasive cancer (52) (histological diagnosis) and age-matched controls (119), employing HSV-2-infected HEp-2 cells as antigen during IFA assay. We observed an elevated geometric mean titre (GMT) of serum antibody (IgG five-to eight-fold and IgA four-to five-fold) for the entire spectrum of cervical lesions, as compared to controls. The odds of finding HSV-IgA antibodies were highest with CIN III (OR = 22.0), followed by invasive carcinoma, and CIN I & II (OR = 9.5 and 5.2), respectively. Furthermore, the investigations with respect to married couples (husbands and wives) who volunteered to participate in this study (33 cases and 47 control group) also indicated relatively high antibody titres and increased frequency of HSV sero positivity amongst husbands of cases as compared to their wives, as well as the control group males and females. The contribution of HSV infection in women and/or their husbands to the risk of developing abnormal cervical lesions was analysed after adjusting for the same in respective counterparts. It was observed that the risk was increased 14-fold with HSV-IgA positivity of women, and that HSV-IgA positivity of husbands (male partners) further increased the risk 16-fold. This preliminary observation shows the importance of serum HSV-IgA antibodies as a risk indicator in cervical precancer and cancer lesions in women without a history of recent genital herpes lesions. The serum HSV-IgA may also be taken as an indicator of "high risk" males.

Adult↗
PubMed1992

Lymphocytic adenosine deaminase activity in typhoid fevers.

Lymphocyte adenosine deaminase (L-ADA) activity, a measure of lymphocyte activity, was estimated in 10 healthy controls and 30 patients with typhoid fever (20 uncomplicated and 10 complicated) at the time of admission, at onset of complications and weekly until recovery. Mean L-ADA activity in healthy controls was 20.49 +/- 3.62 mU/10(6) cells. In uncomplicated patients L-ADA activity was 36.33 +/- 5.09 mU/10(6) cells at time of admission, which is significantly raised as compared to controls. It remained high at the height of the fever and at defervescence. In complicated patients L-ADA activity was significantly low at admission (15.33 +/- 2.35 mU/10(6) cells) and fell further with development of complications (7.86 +/- 4.07 mU/10(6) cells). At defervescence L-ADA activity increased significantly above the control activity (31.24 +/- 5.37). Serial L-ADA activity can be of prognostic significance. A cut-off value of 24 mU/10(6) cells is suggested to predict prognosis and severity of disease. Activity below this indicates a probability of a severe, prolonged course and may help in instituting early and energetic treatment.

Adenosine Deaminase↗
PubMed1992

Effect of lysine residue modification of ovine luteinizing hormone by heterobifunctional crosslinking reagent SPDP on subunit-subunit association, receptor binding and biological activity.

The increasing use of heterobifunctional crosslinking agent in the design of hormone-carrier conjugates for selective targeting or inducing immune response against the hormone has prompted us to study the effect of epsilon-NH2 group modification of oLH-subunit, their recombination, immunoreactivity, receptor binding and biological activity. The epsilon-NH2 groups of oLH alpha and oLH beta subunits were modified by using SPDP. The SPDP modified oLH alpha derivatives hybridize to native OLH beta as judged by RP-HPLC analysis. The sequential modification of alpha and beta subunits led to progressive reduction in immunoreactivity and receptor binding activities. The steroidogenic potential of oLH beta.SPDP.alpha oLH recombinant was relatively comparable. The modification of six or more epsilon-NH2 groups in oLH alpha although recombine fully with native oLH beta but failed to react to anti-oLH antibody. Moreover, steroidogenic activity was also abolished. Introduction up to four SPDP groups in oLH alpha compromised immunological and biological activities but further addition of two more SPDP groups completely abolished antibody reactivity, receptor binding and steroidogenic activity indicating the importance of later two -NH2 groups in the receptor recognition and steroidogenic potential.

Animals↗
PubMed1992

Effect of picroliv on low density lipoprotein receptor binding of rat hepatocytes in hepatic damage induced by paracetamol.

Picroliv from root and rhizome of Picrorhiza kurroa showed reversal of low density lipoprotein (LDL) binding to paracetamol-induced damaged hepatocytes of rats. Changes in levels of glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, alkaline phosphatase, conjugated dienes and lipids of hepatocytes were significantly prevented by picroliv at different doses. The effect of picroliv on enzyme levels, LDL receptor binding and lipids in damaged hepatocytes was found to be comparable to silymarin, a known hepatoprotective agent.

Acetaminophen↗
PubMed1992

Determinant analysis and interaction studies on monoclonal antibodies to bovine IgG1 and IgG2.

Two mouse monoclonal antibodies SKb1 and SKb6 were prepared by fusion of myeloma cells with spleen cells of female Balb/c mouse immunized with a mixture of bovine IgG1 and IgG2. In radioimmunoassay, SKb1 bound specifically to IgG2 but SKb6 reacted with both IgG1 and IgG2 molecules. In the competition experiments, heavy chain isolated from bovine IgG could inhibit the binding of 125I-IgG1 and 125I-IgG2 to SKb6, while it failed to inhibit the binding of 125I-IgG2 to SKb1. The epitope reacting with SKb1 was found to be present not only on bovine IgG2 but also on goat IgG and was not present on IgG molecules isolated from the serum of rabbit, rat, sheep, horse, human and monkey. Similarly, the epitope reacting to SKb6 was found to be present on bovine IgG1 and IgG2 and also on IgG molecules isolated from goat and sheep serum but was absent in the IgG molecules isolated from the serum of rabbit, rat, horse, human and monkey. The association constants of the interactions of SKb1 with 125I-IgG2 and of SKb6 with 125I-IgG1 and 125I-IgG2, determined by Scatchard analysis, Steward-Petty plot and Sips plot, were found to be in the order of 10(8)-10(10) L/M. The association constants were determined at varying temperatures to obtain the thermodynamic parameters. The enthalpy (delta H0) and entropy (delta S0) values for the above antigen-antibody interactions were in the range of 9.15-15.96 kcal/mole and 36.96-41.15 eu/mole respectively. The heterogeneity indices for similar interactions determined by Sips equation were consistent with the expected values for binding of monoclonal antibodies with homogeneous protein determinants.

Animals↗
PubMed1992

Influence of immunogen modification of the gonadotropin releasing hormone antibody reactivity.

The binding of MoAbs and PoAbs to native GnRH, azo-GnRH, GnRH-BSA and azo-GnRH-BSA conjugates was studied using a solid phase ELISA test. The use of carbonate/bicarbonate buffer (pH 9.2) significantly affected the coating of peptide to the ELISA plates. Azo-GnRH coated in PBS showed seven times less binding to MoAb than the native GnRH. Saturation analysis studies indicated comparable binding to the antibodies to the coated GnRH and GnRH-BSA but binding to azo-GnRH-BSA was higher than to azo-GnRH. The epitope recognition ability of MoAbs was therefore investigated. Blocking ELISA additivity tests were performed to analyse whether MoAbs recognised a common epitope involving a conformation or sequence of the modified peptide (azo-GnRH). The plates coated with azo-GnRH or azo-GnRH-BSA and saturated with MoAbs did not bind PoAbs. The inhibition activity was similar when GnRH or GnRH-BSA was used instead of azo-GnRH or azo-GnRH-BSA thus suggesting that the MoAbs were directed against a conformational epitope of the GnRH molecule.

Animals↗
PubMed1992

Immunospecificity and affinity studies on anti-luteinizing hormone releasing hormone antibodies developed by azo-LHRH-TT and azo-LHRH-BSA conjugates.

Monoclonal and conventional antibodies against the 'self' decapeptide LHRH produced by azo-LHRH-TT and azo-LHRH-BSA conjugates were studied for immunoreactivity with native LHRH, azo-LHRH, LHRH (OH) and its fragments of sequence 1-10, 7-10, 4-10 and 4-6. The CoAb reacted 8-20% to azo-LHRH, 2-6% to LHRH-Lys, 1-3% LHRH-LYS-MDP and 0.5-1.68% to LHRH-Ala-Ala-Tuftsin but failed to react to LHRH free acid and its fragments. On the other hand MoAb reacted 4-6% to azo-LHRH and 10-18% to LHRH-Lys, 3-5% to LHRH-Ala-Ala-Tuftsin. These results indicate that the azotization drastically inhibited immunoreactivity but that the azo-LHRH-carrier conjugate preserved the immunogenic epitope responsible for the induction of an effective anti-LHRH antibody response.

Amino Acid Sequence↗
PubMed1992

Coumarin congeners as antidepressants.

3-Carboethyl coumarin (I) was converted to coumarin 3-acid hydrazide (II). This on reaction with appropriate aldehyde yielded 3-arylidino amino coumarin (III). Compound III on diazotisation and reaction with ferric chloride yielded the corresponding formazans viz. 3-substituted phenyl azoarylidino, amido coumarins (IVa1-a10) and oxadiazoles viz. 2-aryl-5-(3-coumarinyl)-1,3,4-oxadiazoles (Va1-a3), respectively. Simultaneously 3-carboethyl coumarin on hydrolysis gave 3-carboxy coumarin (VI) which on reaction with aryl amine in methylene chloride yielded 3-(N-aryl)amido coumarin (VIIa1-a3). The compounds were screened for their antidepressant activity against a tricyclic antidepressant (imipramine). Compounds IVa4, IVa5 and IVa9 exhibited activity better than imipramine with no toxicity (ALD50 greater than 1000 mg/kg) but IVa5 showed some side effects.

Amphetamine↗
PubMed1992

Synthesis and pharmacological evaluation of some phenothiazines as antidepressants.

10-Hydrazino acetyl phenothiazine (II) has been converted to N-10-acetyl amino phenothiazine-N-phenyl thiourea (III) which have been converted to 3-aryl-1-(10-phenothiazine acetyl amino)-2,3-dihydro-2-thioxo-4,6-(1H,5H) pyrimidinones (IV) on condensation with aryl amines and aryl aldehydes yielded 3-aryl-1-(10-Phenothiazine acetyl amino)-5-(substituted phenyl amino methyl)-2,3-dihydro-2-thioxo-4,6-(1H, 5H) pyrimidinediones (Va-k) and 3-aryl-1-(10-phenothiazine acetyl amino)-5-(substituted phenylidine)-2,3-dihydro-2-thioxo-4,6-(1H, 5H) pyrimidinediones (vl-o). The compounds were screened for their antidepressant activity against a tricyclic antidepressant (imipramine). Compounds Va, Vf, Vm and Vi exhibited activity better than imipramine with no toxicity (ALD50 greater than 1000 mg/kg) but Vi showed some side effects.

Amphetamine↗
PubMed1992

Clinical and etiological profile of acute viral hepatitis.

There is a paucity of data on the incidence of sporadic viral hepatitis in Indian children. Clinical, biochemical and etiological profile of 54 patients with acute viral hepatitis was evaluated. Of these, 32 (59.25%) patients had Hepatitis A, 18 (33.33%) had NANB, 2 (3.7%) had Hepatitis B and 2 (3.7%) concurrent Hepatitis A and B infection. It was not possible to distinguish the etiological agents on the basis of the clinical and biochemical profile. Fulminant hepatitis was documented in 8 (14.8%) cases. Children with NANB infection were at a greater risk (p less than 0.05) of developing fulminant hepatitis as compared to Hepatitis A infection.

Acute Disease↗