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Biomedical subjects

K Subramanian

Publications and source records attributed to K Subramanian.

At least 37 records · Page 2Linked to original sources
PubMed1996

Ehretianone, a novel quinonoid xanthene from Ehretia buxifolia with antisnake venom activity.

Ehretianone (1), a new quinonoid xanthene, together with known sterols, was isolated from a MeOH extract of the root bark of Ehretia buxifolia. The structure of ehretianone was elucidated as 7-hydroxy-9a alpha-(3-methylbut-2-enyl)-4a alpha,9 alpha-(2-methylprop-2-enyl)-4a, 9a-dihydro-1,4-dioxoxanthene on the basis of spectroscopic data and X-ray crystallographic analysis. The antisnake venom activity of ehretianone against Echis carinatus venom in mice is also reported.

Animals↗
PubMed1995

Simultaneous cross-linking by two nontriggering bivalent ligands causes synergistic signaling of IgE Fc epsilon RI complexes.

We have used two bivalent ligands that bind IgE to study the relationship between the aggregation of receptors with high affinity for IgE (Fc epsilon RI) and the responses (receptor immobilization, Ca2+ influx, and degranulation) of rat basophilic leukemia (RBL-2H3) cells. One of these is a symmetric bivalent ligand, N,N'-bis[[epsilon-[(2,4-dinitrophenyl)amino]caproyl]-L-tyrosyl]-L- cystine ((DCT)2-cys), which binds specifically to the combining sites of a mAb anti-DNP IgE and efficiently cross-links cell surface IgE, but does not trigger significant degranulation or increases in intracellular Ca2+. Several lines of evidence, including lateral mobility measurements, indicate that this ligand preferentially forms stable cyclic complexes containing two (DCT)2-cys and two IgE. The second ligand is a mAb anti-IgE, B1E3, which causes lateral mobility changes consistent with dimerized IgE-Fc epsilon RI and also does not trigger increases in intracellular Ca2+ or degranulation. The two ligands together trigger robust responses. In the presence of B1E3, (DCT)2-cys causes immobilization of IgE-Fc epsilon RI in a broad concentration range; in a more narrow concentration range, it is a potent stimulant of changes in both degranulation and Ca2+. We have compared the dose-response curves for cellular activation to simulated IgE aggregation curves, i.e., curves that predict the equilibrium IgE aggregate size distribution as a function of the (DCT)2-cys concentration. Our results indicate that maximal cellular activation occurs at a much higher (DCT)2-cys concentration than maximal IgE aggregation. When IgE aggregation is maximal, almost all aggregated IgE is in cyclic dimers. Thus, cyclic dimers appear to be functionally ineffective, even after they have been cross-linked by B1E3. Aggregated IgE-Fc epsilon RI that is effective in stimulating a cellular response may have particular structural or dynamic properties that allow critical interactions for initiating the signaling cascade.

Animals↗
PubMed1995

Spectroscopic studies on the interaction of three partially hydrogenated acridine dyes with calf thymus DNA and their structural comparison.

The interaction of three partially hydrogenated acridine dyes (acridine I, acridine II and acridine III) with calf thymus DNA was studied using spectrophotometric and spectrofluorometric methods. This paper presents the evidence for the formation of complexes between acridine I, II and III with calf thymus DNA. From the results of this studies various binding parameters were evaluated. The binding constant for acridine I and acridine III ranged from 2.1 to 4.4 x 10(5) M-1 for the P/D ratio from 4.29 to 0.56 while for acridine II this constant increased from 0.78 to 2.26 x 10(5) M-1 for the P/D ratio 12 to 2.38 and decreased to 1.47 at P/D ratio 1.34. The Scatchard analysis indicated a cooperative binding of acridine II to calf thymus DNA as compared to acridine I and III. A red shift in the visible absorption bands for dye DNA complexes (for acridine I = 8, acridine II = 7, and acridine III = 9 nm) suggested an electronically coupled interaction mode for the dyes. It is concluded that acridine II interacted stronger with calf thymus DNA than acridine I or III. The results are interpreted in terms of their crystal structures and also with the already reported DNA binder structures.

Acridines↗
PubMed1995

Characterization of 2 aquareovirus proteins.

The protein products of aquareovirus genome segments 10 and 11 were investigated. The genome segment 10 encodes the major outer capsid protein (VP7) of aquareovirus. The VP7 protein has a molecular weight of 35 kDa and was found to be glycosylated. The electrophoretic mobility of VP7 in SDS-PAGE was unaltered when untreated and deglycosylated proteins were compared, indicating the presence of short oligosaccharide chains. Selective binding of lectins with well-defined sugar specificities suggest that most of the short N-linked carbohydrate chains of VP7 contain galactose residues. Genome segment 11 encoded 2 non-structural proteins (NS29 and NS15). Partial protease mapping indicated that the NS29 and NS15 proteins are derived from initiation of protein synthesis at 2 distinct sites.

Animals↗
PubMed1994

Characterization of the polypeptides and determination of genome coding assignments of an aquareovirus.

Proteins of an aquareovirus isolated from striped bass (SBR strain) were examined. Twelve viral-specific proteins ranging in molecular weight from approximately 130 to 15 kDa were identified in infected cells. Purified virions and infected cell lysates were used to characterize the structural and nonstructural proteins of the virus. Seven structural and five nonstructural proteins were identified by SDS-PAGE. Cell-free translation of total SBR virion RNA in a rabbit reticulocyte system resulted in the synthesis of proteins which were both qualitatively and quantitatively very similar to those found in infected cells. Segments 1-10 of the SBR virus genome encoded one protein each, while segment 11 encoded two proteins. The coding assignments of all the purified genome segments were determined by in vitro translation and the in vitro synthesized proteins were found to be viral specific by immunoprecipitation. The major outer capsid protein, VP7, was found to be glycosylated. The electrophoretic mobility of VP7 in SDS-PAGE was not altered when untreated and deglycosylated proteins were compared, indicating the presence of short oligosaccharide chains.

Animals↗
PubMed1994

Evaluation of chronic neurological sequelae after acute pesticide exposure using SPECT brain scans.

A case in which SPECT brain imaging was used in the diagnosis and treatment of chronic effects from acute acetylcholinesterase inhibitor poisoning is presented. The patient was exposed to an insecticide mixture containing phosphorothiate, pyrethrin, piperonyl butoxide, and petroleum distillates, which produced symptoms consistent with acute acetylcholinesterase inhibitor poisoning as well as an upper respiratory tract irritant. Delayed sequelae of gross neurologic symptoms followed, that is, coarse tremor, intermittent hemiballistic movements of the right arm and leg, flaccid muscular tone, fasciculations of muscle groups, muscle cramps, and sensory disturbances. A brain single-photon emission computerized tomography (SPECT) scan was performed 34 mo postexposure, revealing significantly decreased blood flow to the left temporal lobe and to the right and left basal ganglia. The patient's paresthesias were treated with phenytoin, which resulted in worsening of her movement disorder. A trial of amantadine and selegiline (Deprenyl) resulted in a dramatic reduction in dysfunctional movements and ataxia. Post amantadine and selegiline therapy, brain SPECT images revealed significantly improved blood flow with minimally decreased blood flow to the right and left basal ganglia. The use of SPECT scan techniques helped to elucidate objective chronic central nervous system effects subsequent to an acute insecticide exposure and also assisted in the evaluation of the effectiveness of therapeutic intervention.

Adult↗
PubMed1993

Three-dimensional brain metabolic imaging in patients with toxic encephalopathy.

Thirty-three workers, ages 24 to 63, developed clinical toxic encephalopathy after exposure to neurotoxins and were studied by SPECT brain scans. Five were exposed to pesticides, 13 were acutely exposed to mixtures of solvents, 8 were chronically exposed to mixtures of hazardous wastes that contained organic solvents, 2 were acutely exposed to phosgene and other toxins, and 5 had exposures to hydrogen sulfide. Twenty-nine had neuropsychological testing and all had a medical history and physical. Of the workers who had a clinical diagnosis of toxic encephalopathy, 31 (93.9%) had abnormal SPECT brain scans with the most frequent areas of abnormality being temporal lobes (67.7%), frontal lobes (61.3%), basal ganglia (45.2%), thalamus (29.0%), parietal lobes (12.9%), motorstrip (9.68%), cerebral hemisphere (6.45%), occipital lobes (3.23%), and caudate nucleus (3.23%). Twenty-three out of 29 (79.3%) neuropsychological evaluations were abnormal. Other modalities when performed included the following percentages of abnormals: NCV, 33.3%; CPT sensory nerve testing, 91.3%; vestibular function testing, 71.4%; olfactory testing, 89.2%; sleep EEG analysis, 85.7%; EEG, 8.33%; CT, 7.14%; and MRI brain scans, 28.6%. The complex of symptoms seen in toxic encephalopathy implies dysfunction involving several CNS regions. This series of patients adds to the previous experience of brain metabolic imaging and demonstrates that certain areas of the brain are typically affected despite differences in toxin structure, that these lesions can be globally defined by SPECT/PET brain scans, that these lesion correlate well with clinical and neuropsychological testing, and that such testing is a useful adjunct to previous methods. EEG and structural brain imaging such as CT and MRI are observed to have poor sensitivity in this type of patient. Additional metabolic imaging studies need to be done to explore dose, time, and specific toxin effects as well as mechanisms of toxicity and olfactory migration.

Adolescent↗
PubMed1992

Simultaneous patient-side measurement of hemoglobin, glucose, and cholesterol in finger-stick blood.

We describe a multianalyte assay system for patient-side use comprising single-use plastic cartridges and a small monitor. Hemoglobin, glucose, and cholesterol can be simultaneously measured in 3 min in an unmeasured volume of blood. The sample is drawn by capillary action into four channels for delivery to assay-specific stacks containing a set of closely apposed layers. The distal layer is a membrane that acts as the optical surface for reflectance optics. For glucose and cholesterol assays, erythrocytes are removed by a fibrous filter layer and oxidase-peroxidase chemical reactions contained in the optical membrane generate a colored product. For hemoglobin measurement, blood is lysed by detergent contained in a porous disk. The amount of color reaching the optical membrane is measured by fiber optics. To ensure fail-safe operation, sensors verify sample sufficiency and degree of hemolysis. The assays perform comparably with laboratory methods.

Blood Glucose↗
PubMed1991

Heterogeneity in the genome RNAs and polypeptides of five members of a novel group of rotavirus-like viruses isolated from aquatic animals.

Biochemical characteristics of five rotavirus-like viruses isolated from striped bass (Morone saxatilis), turbot (Scophthalmus maximus), smelt (Osmerus mordax) and Atlantic salmon (Salmo salar) in North America and Europe were compared. The genome of each isolate was composed of 11 segments of dsRNA and each isolate had a unique electropherotype in polyacrylamide gels. Agarose gel electrophoresis showed similar RNA profiles for all four isolates from North America, whereas the RNA profile of the isolate from Europe was different. Analysis of virion proteins revealed that each virus had five structural proteins ranging in Mr from 130,000 to 34,000. Each isolate had a unique polypeptide profile but their overall polypeptide patterns were similar. Reciprocal RNA-RNA blot hybridization demonstrated that all these rotavirus-like viruses cross-hybridized with each other except for the isolate from Europe which did not hybridize with the RNA from any of the other isolates. No genetic relationship was found between these rotavirus-like viruses of fish and a true group A rotavirus (SA11).

Animals↗
PubMed1991

The multidimensional impact of chronic pain on the spouse: a pilot study.

Spouses of patients with chronic pain face major challenges in learning to cope with the subsequent changes that occur in family life. This study examined the impact of those changes on the chronic pain patient's spouse, examining the extent and severity of psychosocial adjustment problems and the relationship of social support to the level of adjustment. For the twenty spouses in the study, results indicated that they were adversely impacted in multiple areas of their lives and that high levels of perceived partner support were related to better psychosocial adjustment. A multidimensional assessment instrument is evaluated for clinicians and researchers.

Adaptation, Psychological↗
PubMed1990

Indium 111-labeled granulocyte scan in the diagnosis and management of acute inflammatory bowel disease.

The indium 111 granulocyte scan was used to evaluate 39 individuals known to have or suspected of having inflammatory bowel disease. Twenty-three of these individuals had positive scans and 16 had negative scans. Eighty-seven confirmatory studies, which consisted of barium radiography, endoscopy, operative findings, and histopathology, were performed in 37 of these individuals. The remaining two negative scans corroborated only by clinical course, CBC, and erythrocyte sedimentation rate. In addition, 10 follow-up scans were performed in six of the 39 patients to monitor therapy or investigate a change in symptoms. As an anatomic indicator of acute granulocytic infiltration of the intestinal lamina propria and crypts, the authors found that this scan had a 97 percent rate of sensitivity and 100 percent specificity. Specific indications for the use of the indium 111-labeled granulocyte scan are described. For the authors, in general, this test has become a vital adjunct to endoscopy and radiography in the diagnosis and management of patients with symptoms of inflammatory bowel disease.

Acute Disease↗
PubMed1988

Social work and the treatment of chronic pain.

The severity and prevalence of chronic pain is a growing concern for all health care professionals. An outpatient program that offered cognitive-behavioral coping skills training in a group setting was studied as a possible social work treatment for chronic pain patients, and the results were encouraging. Such treatments usually are available only in hospital pain clinics and research centers, which reduce treatment availability to patients in other settings. Social workers could provide services in a wider variety of settings to a large and growing population. As social workers realize the continuous interplay of physical, emotional, and cognitive factors in the experience of pain, they will identify appropriate practice roles for working with chronic pain patients.

Adaptation, Psychological↗
PubMed1985

Doughnut sign on bone scintigraphy in angioblastic meningioma.

Bone imaging was performed in a patient with a rapidly expanding parietal bone lesion. The findings on the nuclear medicine study showed a doughnut type lesion. The underlying abnormality was found to be an angioblastic meningioma causing local bone destruction.

Diphosphonates↗
PubMed1974

Nucleotide sequences of RNA transcribed in infected cells and by Escherichia coli RNA polymerase from a segment of simian virus 40 DNA.

The nucleotide sequence of 180 residues of an RNA transcript of DNA of simian virus 40 has been deduced. This sequence adjoins a preferred initiation site for E. coli RNA polymerase. Comparison of this sequence with that of complementary RNA of simian virus 40 from infected cells has shown that this site also adjoins the apparent 3' terminus of some of the cytoplasmic complementary RNA of simian virus 40.

Adenoviridae↗