Biomedical subjects

B K Singh

Publications and source records attributed to B K Singh.

At least 37 records · Page 2Linked to original sources

PubMed1996

Application of polymerase chain reaction (PCR) for diagnosis of equine herpes virus-1 (EHV-1).

Fifty aborted foetus samples were diagnosed for the presence of equine herpes virus-1 (EHV-1) by polymerase chain reaction (PCR) technique. Specific primer pair for amplification of a particular segment of EHV-1 DNA in gc region having 3 Hae III restriction endonuclease sites was used. A 409 base pair segment obtained as PCR amplification product in 9 samples was digested with Hae III to confirm the presence of EHV-1 as the infectious agent in aborted tissues. It was observed that PCR technique was more sensitive, specific and rapid than the conventional virological diagnostic methods.

Abortion, Veterinary↗

PubMed1995

Effect of methylxanthines on motility and fertility of frozen-thawed goat semen.

We studied the effects of 2 methylxanthines (caffeine and theophylline) at different concentrations on goat sperm motility and live spermatozoa and on the percentage of acrosomal damage and fertility. Altogether, 144 semen samples collected from 12 bucks (3 each from Black Bengal and Beetal, and 6 from cross-breds) were diluted in TRIS extender, divided into 5 equal fractions; then caffeine and theophylline were added at 2 concentrations (2 and 5 mM) in different fractions. These samples were frozen in liquid nitrogen vapor, thawed at 37 degrees C for 15 sec, and evaluated for motility and other semen attributes. Addition of caffeine and theophylline had a stimulatory effect on goat spermatozoa. It was further observed that the effect of these agents was concentration-dependent, with 2 mM caffeine and 5 mM theophylline yielding the best results in respect to the percentage of motility in all 3 breeds of goats tested. Among the two methylxanthines used, caffeine was found to be the more effective in Improving motility than theophylline. There was no significant effect on the percentages of live spermatozoa and acrosomal damage due to the addition of these 2 methylxanthines to the extender. Fertility rates with Tris + 2 mM caffeine (60.20 %) and with Tris + 5 mM theophylline (58.88 %) extended semen were apparently higher than those with the Tris-diluted semen (50.0 %), although these differences were not significant.

Journal Article↗

PubMed1995

Effect of cryoprotectants on certain seminal attributes and on the fertility of buck spermatozoa.

Semen samples were obtained from 12 bucks (3 Beetal, 3 Black Bengal and 6 Beetal x Black Bengal) and 10 different extenders were constituted with varying concentrations of glycerol, DMSO, glycerol + DMSO and glycerol + lactose as the sperm cryoprotective agents. After the collection of semen samples, they were assessed for quality, diluted in different extenders after removal of seminal plasma, packaged in ministraws and frozen after equilibration (5'C) for 5 h. The samples were evaluated immediately after equilibration and again 24 h after freezing for progressive motility, percentage of live spermatozoa and acrosome, head and tail abnormalities. Both motility and the percentage of live spermatozoa were most affected by extenders containing only DMSO and these values improved in glycerol + DMSO extenders as the concentration of glycerol was increased while DMSO was decreased. However, these values were significantly higher in extenders containing glycerol + lactose as the cryoprotective agents, and were found to increase with increased concentration of lactose, being highest in TYGL (180). Acrosomal and tail abnormalities tended to increase between post equilibration and post thawing stage, and were higher in extenders containing the higher levels of DMSO. Significantly (P < 0.01) lower percentages of abnormalities were recorded in the glycerol + lactose extenders. The fertility results showed nonsignificant effect of extenders on the conception rate of does.

Journal Article↗

PubMed1994

Biosynthesis of lysine in plants: the putative role of meso-diaminopimelate dehydrogenase.

Extracts from Chlamydomonas, corn, soybean and tobacco were tested for enzymes of the lysine biosynthetic pathway. Dihydrodipicolinic acid (DHD) synthase, DHD reductase, diaminopimelate (DAP) epimerase and DAP decarboxylase were present in all. However, in contrast to the report of Wenko et al., meso-DAP dehydrogenase could not be detected in extracts prepared from soybean. Moreover, it was not found in Chlamydomonas, corn and tobacco as well. In order to set an upper limit to the amount of meso-DAP dehydrogenase that might be present, reconstruction experiments were performed with soybean and corn extracts in which the conversion of dihydrodipicolinate to lysine was made dependent on the addition of limited amounts of the meso-DAP dehydrogenase purified from Bacillus sphaericus. The presence of DAP epimerase and the absence of meso-DAP dehydrogenase indicates that the meso-DAP dehydrogenase abbreviated pathway for lysine synthesis is not operative in plants.

Amino Acid Isomerases↗

PubMed1994

Sex differences in self-report of physical health by injection drug users.

Through heterosexual contact, injection drug users (IDUs) put others at risk of contracting Human Immunodeficiency Virus (HIV) disease. Self-report of health was compared among IDUs in Laredo, Texas, San Diego, California, and San Juan, Puerto Rico, and in a subsample which contained HIV positive subjects from these cities. These data were compared with similar National Opinion Research Center data and indicated that IDUs do not report their health to be different from that of the general public. Previous research has reported sex differences in morbidity and mortality in the non-IDU population. This study found sex differences in perception of health by IDUs in Laredo and San Diego.

Acquired Immunodeficiency Syndrome↗

PubMed1994

Urban youth, fear of crime, and resulting defensive actions.

One of the most neglected populations studied in victimology has been juveniles. The present study examines the impact of fear of crime among a sample of urban youth on their defensive actions. Studies of urban adult populations have found that a significant number of people fear to venture outside their homes at night. When they do go out, they often take defensive measures to insure their safety. Carrying "mace," whistles, guns, knives, and clubs, for example, is not uncommon. Some have indicated that they have undertaken training in a variety of self-defensive arts and/or keep dogs to protect themselves from the possibility of being victimized. Using data collected from a sample of 1,775 urban youth in 1986 it was found that this population has taken many of the same defensive actions. Only 11% of the sample indicated that they had not taken any defensive actions as a result of fear of crime. Nearly three-fifths took the precaution of having an escort when they went out at night. Learning a technique of self-defense was reported by 19% of the sample; 10% indicated that they carried "mace" or some other type of repellant. Only 4% reported that they carried a whistle because of crime concerns. Significant predictors of personal defensive actions include gender, crime-witnessing status, victimization status and type of victimization (theft vs. witnessing Other defensive actions taken by members of the respondents' households included installing a burglar alarm (22%), keeping a "trained dog" (17%), keeping lights on a night (39%), and installing security locks (38%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

A high-performance liquid chromatography assay for threonine/serine dehydratase.

Threonine dehydratase, a key enzyme leading to the biosynthesis of isoleucine, catalyzes the production of 2-ketobutyrate from threonine. An uv/fluorometric HPLC assay for threonine dehydratase has been developed that involves derivatization of the 2-ketoacids produced by the enzyme using a specific derivatizing agent, o-phenylenediamine. The derivatized ketoacids can be detected spectrophotometrically or fluorometrically. This novel assay is over 1000-fold more sensitive than the commonly used dinitrophenyl hydrazine derivatization assay. In addition, the HPLC assay allows the identification of the reaction product(s), and can be used to examine the reaction using mixtures of the two substrates, threonine and serine.

Chromatography, High Pressure Liquid↗

PubMed1993

Immunogenicity of wild-type and vaccine strains of Japanese encephalitis virus and the effect of haplotype restriction on murine immune responses.

The Chinese live attenuated Japanese encephalitis (JE) virus vaccine clone SA14-14-2 produced in primary hamster kidney (PHK) cells has been adapted to primary dog kidney cells (PDK) for use as a live attenuated human vaccine. In this study we have compared the immunogenicity in mice of SA14-14-2 (PDK) and SA14-14-2 (PHK); also included was the wild-type parent to the vaccine clones, SA14, and another wild-type JE virus strain Nakayama (original). It was found that Balb/c (H-2d) mice given a single dose of 10(3) or 10(6) p.f.u. of live SA14-14-2 (PHK) virus elicited a superior neutralizing (N) antibody response as compared to the same dosages of live SA14-14-2 (PDK) virus. However, if the vaccine clones were inactivated and administered in a two-dose regime the N antibody response elicited was similar for the two viruses. This observation may be explained by differences in the replication efficiency in vivo of the respective vaccine clones. The humoral immune response to all the virus strains in this study elicited by different inbred mouse strains each carrying a discrete haplotype (Balb/c (H-2d), C3H (H-2k), C57BL/6 (H-2b)) were also assessed using haemagglutination inhibition (HAI) and N assays. Viruses were shown to elicit patterns of high and low N-antibody response depending on the major histocompatibility complex (MHC) make-up of the mouse strains. However, the patterns did not necessarily coincide when HAI and N titre reactivity patterns were compared for the same virus strain.

Animals↗

PubMed1993

Findings from the Horizontes Acquired Immune Deficiency Syndrome Education project: the impact of indigenous outreach workers as change agents for injection drug users.

A human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) intervention using indigenous outreach workers was implemented with Hispanic injection drug users (IDUs) and their sexual partners in three locations: Laredo, Texas; San Diego, California; and San Juan, Puerto Rico. A total of 2,169 subjects were contacted, given health education, HIV antibody testing, and follow-up counseling. This article reports on the 1,616 IDUs (75%) who completed the initial and follow-up interviews. The results indicated significant increases in health knowledge on AIDS, decreases in needle risk drug taking behaviors, some decreases in sex risk behaviors, and more realistic perceptions of personal AIDS risk. Using multivariate analyses, gender (male) and increasing age (older than age 25 years) were the strongest predictors of behavior change. Surprisingly, the identification of a positive HIV serostatus was not a significant predictor of behavior change. Although intended as a comparison study between contrasting levels of intervention, logistical and administrative problems undermined the use of a true quasi-experimental design. Nonetheless, the results from this research suggest that the use of indigenous outreach workers is an effective means of combatting the spread of HIV in this difficult to reach population. Some programmatic recommendations are provided for future efforts of this kind, particularly in relation to role conflicts experienced by outreach workers.

Adolescent↗

PubMed1993

Sexual risk behavior among injection drug-using human immunodeficiency virus positive clients.

This study examined sexual risk behavior of 154 seropositive Hispanic injection drug-using clients who were a subsample of a larger study. The results revealed that while nearly 71% followed safe sex practices at a 6-month follow-up, the other 29% were following risky sexual behaviors. Among males who were 25 years of age or younger, slightly over 58% were practicing unsafe sex. Among females, those in the 31-35 age group were all following risky sexual behaviors. Generally, those who lived with their sexual partners, females, and younger clients tended to follow risky sexual behaviors. These findings are very significant in the light of the heterosexual transmission of Human Immunodeficiency Virus (HIV). Educational and case management programs are needed to provide such clients with an understanding of the possibility of HIV transmission to their sexual partners and to their children in case of pregnancies.

Adult↗

PubMed1993

Production of monoclonal antibodies against equine influenza A/Equi-2 (H3N8) Indian isolate.

Seven hybrid cell lines of mouse myeloma cell line NSO and spleen cells of BALB/c mice producing monoclonal antibodies (MAbs) against equine influenza A/Equi-2/Ludhiana/87 (H3N8) virus were developed. These MAbs were purified, isotyped and characterised by enzyme linked immunosorbent assay (ELISA), fluorescent antibody test (FAT), haemagglutination inhibition (HI) and virus neutralization (VN) tests. The titres of ascitic fluids induced by hybridomas as estimated by ELISA ranged from 1:25,600 to 1:51,200. Monoclonality of these clones was confirmed using a panel of 5 viral antigens, each belonging to a single isotype. MAbs (5) belonged to IgM and one each to IgG1 and IgG2a. Two epitopes appeared to be closely resembling by HI and VN tests but other two epitopes appeared to be different.

Animals↗

PubMed1993

Antiepileptic drug status in adult outpatients with mental retardation.

Charts of 100 patients with mental retardation and epilepsy from the community were reviewed to survey use of antiepileptic drugs and examine the relation of mental retardation and seizure type to antiepileptic drug status. Sixty patients were on monotherapy and 40, on two or three antiepileptic drugs. Most subjects had generalized tonic-clonic seizures (68%), but there was a trend for those with profound retardation to have relatively more mixed seizures. Subjects on more than one antiepileptic drug were less likely to have fully controlled seizures (50%). Individuals with mixed seizures were comparatively more likely to be on more than one antiepileptic drug and have uncontrolled seizures. Implications for clinical management of epilepsy in adults with mental retardation were discussed.

Adolescent↗

PubMed1992

Pyogenic liver abscess causing acute Budd-Chiari syndrome.

Acute Budd-Chiari syndrome caused by compression of the inferior vena cava by a space-occupying lesion in the liver is rare in children. We report a case where the compression was due to a large staphylococcal abscess in the right lobe of the liver. A high index of suspicion in such a case ensures early intervention and saves life.

Acute Disease↗

PubMed1992

Tolerance to imidazolinone herbicides in wheat.

An imidazolinone-tolerant wheat (Triticum aestivum L. em Thell) mutant in the winter wheat cultivar Fidel has been identified and characterized. The mutant was isolated from a population derived through seed mutagenesis of the variety with an aqueous solution containing sodium azide. Imidazolinone-tolerant wheat seedlings were selected from the M(2) generation of the population in the presence of imazethapyr herbicide and identified as herbicide-insensitive individuals. The trait is inherited as a single semidominant gene and confers high levels of tolerance to imazethapyr. Acetohydroxyacid synthase activity in extracts from imidazolinonetolerant plants was less inhibited by imazethapyr than the enzyme from the wild type. The herbicide-tolerant plants have a completely normal phenotype and display no negative effects on growth and yield in either the absence or presence of imazethapyr.

Journal Article↗

PubMed1991

Production of a monocot-specific monoclonal antibody against acetohydroxyacid synthase and its use in the purification and characterization of the enzyme.

Acetohydroxyacid synthase [AHAS; acetolactate pyruvate-lyase (carboxylating), EC 4.1.3.18], the first enzyme unique to the biosynthesis of valine, leucine, and isoleucine, is a known target for several different chemical classes of herbicides. Antibodies required for immunological characterization of the enzyme have not been generated by the conventional method of antibody production using purified protein. Monoclonal antibodies were raised against AHAS from corn by using as immunogen a synthetic peptide representing this enzyme. This antibody immunoprecipitated the enzyme activity from corn. On a Western blot, a protein band with a molecular weight of 65,000 was detected in crude extracts of corn. Furthermore, a monoclonal antibody immunoaffinity gel was used to isolate a single protein from crude enzyme preparations that migrated at Mr 65,000 in an SDS/polyacrylamide gel. The molecular weight of this protein band is the molecular weight predicted for a plant AHAS from a cloned gene sequence. These results strongly suggest that the Mr 65,000 protein represents AHAS in corn extracts. Interestingly, the monoclonal antibody specifically recognized the enzyme from monocots and did not crossreact with AHAS from any dicot species tested. Identification of this monoclonal antibody that distinguishes monocot and dicot AHAS is significant because of a very high degree of amino acid conservation (85%) between AHAS proteins from different species.

Acetolactate Synthase↗

PubMed1991

Imidazolinone-induced loss of acetohydroxyacid synthase activity in maize is not due to the enzyme degradation.

Acetohydroxyacid synthase (AHAS), the first enzyme leading to the biosynthesis of valine, leucine, and isoleucine, is inhibited by different chemical classes of herbicides. There is a loss in the extractable AHAS activity in imidazolinone-treated plants. Immunological studies using a monoclonal antibody against AHAS revealed no degradation of AHAS protein in imidazolinone-treated maize (Zea mays) plants. Therefore, the loss in AHAS activity is not due to the loss of AHAS protein.

Journal Article↗

PubMed1989

Equine coital exanthema (EHV-3 virus) infection in India.

A progenital disease encountered at one equine stud farm at Bangalore in Southern India during 1987 was investigated and confirmed as equine coital exanthema on the basis of characteristic lesions and clinical symptoms, isolation of equine herpes virus-3 (EHV-3) from the scabs collected from animals having active lesions and demonstration of neutralizing antibodies in the sera of recovered mares and stallion. This is the first authenticated report of the occurrence of equine coital exanthema in India due to EHV-3.

Animals↗

PubMed1988

Assay of acetohydroxyacid synthase.

Acetohydroxyacid synthase (AHAS), also known as acetolactate synthase, has received attention recently because of the finding that it is the site of action of several new herbicides. The most commonly used assay for detecting the enzyme is spectrophotometric involving an indirect detection of the product acetolactate. The assay involves the conversion of the end product acetolactate to acetoin and the detection of acetoin via the formation of a creatine and naphthol complex. There is considerable variability in the literature as to the details of this assay. We have investigated a number of factors involved in detecting AHAS in crude ammonium sulfate precipitates using this spectrophotometric method. Substrate and cofactor saturation levels, pH optimum, and temperature optimum have been determined. We have also optimized a number of factors involved in the generation and the detection of acetoin from acetolactate. The results of these experiments can serve as a reference for new investigators in the study of AHAS.

Acetoin↗