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Biomedical subjects

B K Singh

Publications and source records attributed to B K Singh.

At least 19 recordsLinked to original sources
PubMed2002

Oxidized low-density lipoprotein receptor LOX-1 and apoptosis in human atherosclerotic lesions.

BACKGROUND: Lectin-like oxidized LDL receptor-1 (LOX-1), a novel receptor for oxidized low-density lipoprotein, mediates oxidized low-density lipoprotein-induced apoptosis of endothelial cells, monocyte adhesion to endothelium, and phagocytosis of aged cells. The present study examined the role of LOX-1 and apoptosis in human atherosclerotic lesions. METHODS AND RESULTS: Grafted vein (n = 8), human carotid artery endarterectomy (n = 11), and normal human internal mammary artery (n = 8) specimens were used to study the expression of LOX-1 and apoptosis. LOX-1 expression was determined by reverse transcriptase-polymerase chain reaction, Western analysis, and immunostaining. Presence of apoptosis was determined by fluorescent in situ nick end-labeling staining and by the presence of poly (ADP-ribose) polymerase protein (an apoptotic marker). Expression of LOX-1 was significantly increased in atherosclerotic grafted vein and carotid artery specimens compared with that in normal arteries. LOX-1 was expressed in endothelial cells, macrophages, and smooth muscle cells. LOX-1 was extensively expressed in the new blood vessels in the core of advanced atherosclerotic lesions. Double immunostaining showed LOX-1 expression to be colocalized with apoptotic cells. Fluorescent in situ nick end-labeling staining showed that the apoptotic cells were present mostly in the rupture-prone regions of the atherosclerotic plaque. CONCLUSION: These observations indicate that LOX-1 is extensively expressed in the proliferated intima of grafted veins and in advanced atherosclerotic carotid arteries. Further, LOX-1 is colocalized with apoptotic cells. These observations may relate to the phenomenon of plaque rupture, and provide targets for developing new therapies.

Aged↗
PubMed2001

Automated mode-of-action detection by metabolic profiling.

Rapid classification and identification of the mode-of-action of bioactive compounds applied to plants can be achieved by a robust and easy-to-use metabolic-profiling method. This method uses artificial neural network analysis of one-dimensional proton NMR spectra of aqueous plant extracts to rapidly classify changes in the total metabolic profile caused by application of crop protection chemicals.

Automation↗
PubMed2001

Tangential views of the articular surface of the distal radius-aid to open reduction and internal fixation of fractures.

Open reduction and internal fixation of comminuted, displaced intra-articular or potentially unstable fractures of the distal radius with plate and screws has increasingly become a favoured treatment. Intra-operative assessment of fixation with the help of an image intensifier has always been difficult because of the anatomy of the distal radius. Imaging of the implants placed as distal as possible to achieve satisfactory fixation often shows the screws to be penetrating the joint. We describe two new radiographic views of the wrist joint, which we used intra-operatively in ten patients undergoing open reduction and internal fixation of distal radius fractures. Screws were thought to have been penetrating the joint in the standard lateral views of all of them and in the standard antero-posterior views of eight of them.However, no screw was seen penetrating the joint in these new views. It was hence possible to place the plate distal enough to enable the screws to engage the sub-chondral bone. We recommend the use of these views in the open reduction and internal fixation of distal radius fractures.

Bone Plates↗
PubMed2001

Neutralizing and complement-fixing monoclonal antibodies as an aid to the diagnosis of equine herpesvirus-1 infection.

One complement-fixing (C-MAb) and three complement-dependent neutralizing monoclonal antibodies (N-MAbs) were raised against Hisar-90-7 equine herpesvirus-1 (EHV-1) strain. The target antigen of the C-MAb (2A5) and two of the N-MAbs (1H6, 9C4) was identified as a 140 kDa polypeptide in Western blotting. The target antigen of N-MAb (9C6) could not be identified. Purified polypeptides of five EHV-1 strains isolated from different regions and at different times gave intense bands at 140 kDa when reacted with N-MAb (1H6) in Western blots. In sandwich ELISA, all four MAbs captured the viral antigen from clinical materials, giving a reliable and rapid diagnosis of EHV-1 infection in equines.

Animals↗
PubMed2000

Noninvasive characterization of stunned, hibernating, remodeled and nonviable myocardium in ischemic cardiomyopathy.

OBJECTIVES: We evaluated a novel protocol of dual-isotope, gated single-photon emission computed tomographic (SPECT) imaging combined with low and high dose dobutamine as a single test for the characterization of various types of altered myocardial dysfunction. BACKGROUND: Myocardial perfusion tomography and echocardiography have been used separately for the assessment of myocardial viability. However, it is possible to assess perfusion, function and contractile reserve using gated SPECT imaging. METHODS: We studied 54 patients with ischemic cardiomyopathy using rest and 4 h redistribution thallium-201 imaging and dobutamine technetium-99m sestamibi SPECT imaging. The sestamibi images were acquired 1 h after infusion of the maximal tolerated dose of dobutamine and again during infusion of dobutamine at a low dose to estimate contractile reserve. Myocardial segments were defined as hibernating, stunned, remodeled or scarred. RESULTS: Severe regional dysfunction was present in 584 (54%) of 1,080 segments. Based on the combination of function and perfusion characteristics in these 584 segments, 24% (n = 140) were labeled as hibernating; 23% (n = 136) as stunned; 30% (n = 177) as remodeled; and 22% (n = 131) as scarred. Contractile reserve, represented by improvement in wall motion/thickening by low dose dobutamine, was observed in 83% of stunned, 59% of hibernating, 35% of remodeled and 13% of scarred myocardial segments (p<0.05). CONCLUSIONS: It is possible with this new imaging technique to characterize dysfunctional myocardium as stunned, hibernating, remodeled and nonviable. These subtypes often coexist in the same patient.

Aged↗
PubMed2000

Aliphatics from Peristrophe bicalyculata.

The isolation and spectral data of the new 14-methyl-tritriacont-14-en-15-ol (1) and 35-hydroxynonatriacontanal (2) from the aerial parts of Peristrophe bicalyculata are reported.

Alcohols↗
PubMed1999

Biodegradation of lindane (gamma-hexachlorocyclohexane) by the white-rot fungus Trametes hirsutus.

The ability of the white-rot fungus Trametes hirsutus to degrade an insecticide, lindane, in liquid culture was investigated and compared with that of Phanerochaete chrysosporium. Trametes hirsutus degraded lindane faster than P. chrysosporium but the mechanism of degradation appears to be the same in both. Two metabolites identified in both fungi were tetrachlorocyclohexane and tetrachlorocyclohexanol. The presence of lindane alone inside the mycelium ruled out the involvement of any intracellular enzyme(s) during the initial step of lindane degradation. Lindane at a concentration of 0.27 mumol l-1 exhibited no adverse effect on fungal growth.

Basidiomycota↗
PubMed1998

Pseudo-pseudoaneurysm of the left ventricle.

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.

Aged↗
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↗
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↗