Biomedical subjects
Publications and source records attributed to B K Singh.
Left ventricular pseudoaneurysms are an uncommon complication of myocardial infarction and need urgent surgical repair. Though it is critical that they be accurately identified, pseudoaneurysms are occasionally misdiagnosed. We report an abnormality which may be mislabeled a pseudoaneurysm which we term a pseudo-pseudoaneurysm. The approach to accurate diagnosis of pseudoaneurysms is discussed.
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.
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.
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.
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)
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
The hydroxynitrile lyase (EC 4.1.2.--) which catalyzes the dissociation of the cyanohydrins of acetone and 2-butanone has been isolated and purified from young seedlings of flax (Linum usitatissimum L.). The purification procedure involved precipitation with (NH4)2SO4, chromatofocusing, and chromatography on DEAE-cellulose, hydroxylapatite, Sephacryl 200, and Matrex Red A gel columns with a final recovery of 21%. Purification of 136-fold yielded an apparently homogeneous preparation that, in contrast to the lyases isolated from Prunus species, is not a flavoprotein. The subunit molecular weight of 42,000 was estimated by gel electrophoresis in the presence of sodium dodecyl sulfate. The native molecular weight of the enzyme was estimated by gel filtration (HPLC) to be 82,000. The enzyme has a narrow pH optimum around 5.5 and is highly stable at 4 degrees C.
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The enzyme mandelonitrile lyase (EC 4.1.2.10) which catalyzes the decomposition of the cyanohydrin of benzaldehyde has been isolated and purified to homogeneity from mature seeds of the California cherry (Prunus lyonii). The purification procedure involved chromatography on DEAE-cellulose and Con-A-Sepharose with a final recovery of 60% of enzyme activity. Purification of only 4.3-fold yielded a nearly homogeneous preparation. The absorption spectrum of this protein shows maxima at 278, 389, and 463 nm, indicative of its flavoprotein character. The native molecular weight for the lyase was found to be 50,000. The subunit molecular weight of 59,000 was estimated by gel electrophoresis in the presence of sodium dodecylsulfate. The isoelectric point was estimated to be 4.75. The enzyme has a narrow pH optimum around 5.5 and is highly stable at 4 degrees C.