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Biomedical subjects

R Singh

Publications and source records attributed to R Singh.

At least 541 records · Page 30Linked to original sources
PubMed1990

Characterization of amyloplastic phosphohexose isomerase from immature wheat (Triticum aestivum L.) endosperm.

Phosphohexose isomerase from amyloplasts of immature wheat endosperm was purified 133-fold. The enzyme had a molecular weight of 130 kDa and maximum activity at pH 8.6. It showed normal hyperbolic kinetics for both fructose-6-P and glucose-6-P with Km of 0.12 mM and 0.44 mM, respectively. pH had a great influence on Km for fructose-6-P. Using glucose-6-P as the substrate, the equilibrium was reached at 23% fructose-6-P and 77% glucose-6-P and an equilibrium constant of about 3.0. The delta F calculated from the apparent equilibrium constant was +742 cal.mol-1. The activation energy calculated from the Arrhenius plot was 7450 cal.mol-1. None of the sulphydryl reagents at 2.5 mM concentration inactivated the enzyme. The enzyme was competitively inhibited by 6-phosphogluconate, ribose-5-P and ribulose-5-P with Ki values of 0.18, 0.14, and 0.13 mM, respectively. The probable role of the enzyme in starch biosynthesis in amyloplasts is discussed.

Glucose-6-Phosphate Isomerase↗
PubMed1990

Dietary modulators of blood pressure in hypertension.

To study the role of diet, 197 patients of essential hypertension were randomized to either experimental diet (group A, 97 cases) or normal diet (group B, 100 cases) with diuretics given to both the groups. The age varied between 25 and 65 years and 154 were males. The study diet included a significantly higher content of potassium (K), magnesium (Mg), calcium (Ca), polyunsaturated fat, and complex carbohydrates compared to the normal diet. At entry to the study, age, sex, risk factors, mean blood pressures, mean serum Mg, K, Ca, and Na, and drug therapy were comparable in both groups. After 1 year of follow-up, there were significantly fewer patients with resistant hypertension in group A (5) than in group B (17). Mean systolic (148.22 +/- 10.1 mm Hg) and diastolic (90.2 +/- 4.84 mm Hg) pressures in group A were lowered compared to mean systolic (160 +/- 12.0 mm Hg) and diastolic (103.3 +/- 5.8 mm Hg) pressures in group B and initial mean systolic (152.2 +/- 12.8 mm Hg) and diastolic (99.8 +/- 7.2 mm Hg) pressures. Mean serum magnesium (1.86 +/- 9.22 mEq/l) and potassium (4.86 +/- 0.39 mEq/l) levels in group A were significantly higher compared to mean levels of 1.56 +/- 0.11 and 4.0 +/- 0.29 mEq/l, respectively, in group B. However compared to initial levels, K and Mg showed no significant changes in groups A and B. There was a significantly lower incidence of complications in group A (58) compared to group B (100). It is possible that a diet low in Na/K ratio and rich in complex carbohydrates, polyunsaturates, K and Mg may cause a significant reduction in blood pressure and its complications.

Adult↗
PubMed1990

Effect of pea and lentil lectins on in vitro absorption of nutrients.

In vitro absorption of nutrients like glucose, leucine, protein hydrolysate and Ca2+ by ligated loops of small intestine was significantly affected in presence of lectins from peas and lentils. Except for sucrose, all other nutrients showed significant decrease in their absorption in presence of lectins. Lentil lectins had a greater inhibitory effect than pea lectins.

Animals↗
PubMed1990

Serum cholesterol binding reserve and its ratio to serum cholesterol in first degree relatives of patients with ischaemic heart disease.

Serum total cholesterol and serum cholesterol binding reserve (SCBR) were estimated in 50 healthy subjects and 25 cases with ischaemic heart disease (IHD) and their seventy asymptomatic first degree relatives. In normal subjects mean values of SCBR tended to expand with increasing levels of serum cholesterol, while this relationship was reversed in cases with IHD. The relatives showed a direct correlation between serum cholesterol and SCBR upto serum cholesterol level of 220 mg/dl, but the correlation was lost beyond this level. The critical levels for predicting risk of IHD were 30 mg/dl for SCBR and 8 for cholesterol: SCBR ratio. The latter was found to be a more sensitive index for predicting the risk of IHD as compared to SCBR alone.

Adult↗
PubMed1990

Right precordial mapping. Diagnostic sensitivity and specificity of leads V3R to V6R in different intercostal spaces in cases with right ventricular infarction.

Twelve lead conventional electrocardiography and right precordial mapping including precordial leads V2R to V6R in the 2nd to 5th intercostal spaces were obtained in 150 cases with acute myocardial infarction. There were 27 (18%) cases with right ventricular infarction: 24 associated with inferior wall infarction and 3 with anterior wall infarction. In the right precordial mapping, leads V3R to V6R in all intercostal spaces had equal sensitivity of 100%; 3rd intercostal space recording, however, had the maximum specificity of 92.6%.

Electrocardiography↗
PubMed1989

[Patients' condition one year following surgery for a lumbosacral radicular syndrome].

In 492 patients with a lumbosacral radicular syndrome caused by a lumbar intervertebral disc herniation or by a stenosis of the lumbar spinal canal, the situation 1 year after a root decompressing operation was compared with the situation before surgery. About 75% of the patients reported satisfactory improvement, while about 10% were not satisfied. The judgement of the physicians is somewhat more favourable: 80% and 5%, respectively. The best results are obtained in patients in whom the preoperative diagnosis of lumbar disc herniation is highly probable; the worst results are obtained in patients undergoing a second operation. Back pain, sometimes serious, persists after surgery in about 50% of the patients. Such persistent back pain occurs most frequently in patients with a lumbar canal stenosis; one-third even mention a postoperative increase in back pain. About 50% of the patients who were on sick leave before operation resumed work afterwards.

Adult↗
PubMed1989

[Effect of surgery on neurological involvement caused by a lumbosacral radicular syndrome].

Results of neurological assessment one year after surgical treatment of herniated lumbar intervertebral disc and lumbar stenosis are reported in 443 patients. Follow-up was performed during one year after operation. Preoperatively, surgeons found motor loss more frequently than patients, (28 and 12% respectively) and, postoperatively, motor loss was still present in 25% and 24%, respectively, of these cases. The operation had caused motor loss in 5% and aggravated motor loss in 3%. Sensibility was reported as abnormal one year after surgery by both patients and surgeons in one-third of the cases. Sensory loss, considered by the patient to have been caused or aggravated by the operation, occurred in 15% of the cases and in 12% of these the surgeons agreed. Preoperatively, unilaterally diminished knee and Achilles tendon reflexes were found in 9% and 42% respectively; one year after surgery, these had recovered in 65% and 57%, respectively. Surgery caused or aggravated unilaterally diminished knee or ankle jerks in 3% and 10%, respectively.

Adult↗
PubMed1989

Rat nucleolar 7-2 RNA is homologous to mouse mitochondrial RNase mitochondrial RNA-processing RNA.

7-2 RNA (also termed RNA M and 7SM RNA) is a noncapped small RNA present in small ribonucleoprotein particles; these particles are present in the granular compartment of the nucleolus. Some sera from patients with scleroderma specifically immunoprecipitate 7-2 RNA-containing particles (Hashimoto, C., and Steitz, J. A. (1983) J. Biol. Chem. 258, 1379-1382; Reddy, R., Tan, E. M., Henning, D., Nohga, K., and Busch, H. (1983) J. Biol. Chem. 258, 1383-1386; Reimer, G., Raska, I., Scheer, U., and Tan, E.M. (1988) Exp. Cell Res. 176, 117-128). In this study, the primary sequence of Novikoff hepatoma 7-2 RNA was determined and a possible secondary structure is presented. The Novikoff hepatoma 7-2 RNA is 94% homologous to the recently described mouse mitochondrial RNase MRP RNA, suggesting that Novikoff hepatoma 7-2 RNA may be the homologue of mouse MRP RNA. The presence of 7-2 RNA in nucleoli and in mitochondria suggests that 7-2 ribonucleoproteins, in addition to being essential components of mitochondrial RNase, may also be functional in nucleolar RNA processing and ribosome biogenesis.

Animals↗
PubMed1989

Novel astrocytic protein in multiple sclerosis plaques.

Monoclonal antibody J1-31 (MAb J1-31, isotype IgG 2b) was raised against crude homogenate of brain tissue from a multiple sclerosis (MS) patient (autopsy sample; Malhotra et al.: Microbios Letters 26:151-157, 1984). In human brain, MAb J1-31 recognizes an intracellular protein antigen (J1-31 antigen), which bands at approximately 30,000 daltons under reducing conditions for sodium dodecyl sulfate gel electrophoresis (Singh et al.: Bioscience Reports 6:73-79, 1986). By immunofluorescence microscopy, MAb J1-31 stains those cells that are also stained by antiserum to glial fibrillary acidic protein (GFAP), namely astrocytes, retinal Müller cells, and tanycytes in the ependyma (Predy et al.: Bioscience Reports 7:491-502, 1987). In addition, MAb J1-31 stains ciliated ependymal cells that do not express GFAP. Using a model system for gliosis (laceration-type injury of rat spinal cord), we were able to show that astrocytes responding to central nervous system injury exhibit greatly enhanced staining for J1-31 antigen (Predy et al.: Journal of Neuroscience Research 19:397-404, 1988; Predy and Malhotra: Brain Research Bulletin in press, 1989). In this article, we demonstrate that immunofluorescence staining owing to MAb J1-31 is greatly enhanced in MS plaques, as compared to adjacent "apparently normal" white matter. (This is consistent with previous results as MS plaques characteristically show an astroglial response [reactive gliosis] leading to the formation of a glial scar [McKhann: Annual Review of Neuroscience 5:219-239, 1982].) In addition, we present further evidence that J1-31 antigen is distinct from GFAP, although these two proteins may be associated spatially with one another.

Animals↗
PubMed1989

Endoscopic removal of impacted Sengstaken-Blakemore tube.

In developing countries, the Sengstaken-Blakemore tube (SB tube) is one of the common treatment modalities for controlling hemorrhages from bleeding esophageal varices. Its use is accompanied by numerous complications. An unusual complication is impaction of a SB tube and its endoscopic removal is described.

Esophageal and Gastric Varices↗
PubMed1989

Morphine-induced inhibition of ovulation in normally cycling rats: neural site of action.

Intracerebral injection of morphine (3 micrograms/0.2 microliter of solvent) on the day of proestrus at 1200 hr bilaterally in the medial preoptic area (mPOA) and median eminence-arcuate (ME-ARC) region inhibited ovulation in the cycling female rats. The morphine antagonist, lethidrone (2 micrograms/0.2 microliter of solvent) when injected in the mPOA and ME-ARC region followed by intraperitoneal morphine (3 mg/100 g body weight) administration, was found to reverse the ovulation blocking action of this opiate. Implantation site at which morphine was effective in blocking ovulation were restricted to a narrow medial band encompassing the mPOA and ME-ARC region. Our data are consistent with the view that the endogenous opioid peptides in mPOA and ME-ARC region of the hypothalamus may be involved in the physiological regulation of the central neural events which lead to ovulation in the rat.

Animals↗
PubMed1989

Distribution of zinc in parasitic helminths.

The distribution of zinc in representative groups of parasitic helminths was determined by the use of the atomic absorption spectrophotometer. The results of these analyses have shown that growing flukes (smaller forms) with active oogenesis and spermatogenesis contained more zinc than old (large) or very old adults with an empty uterus and large lobulated testes. In cestodes, the neck region and immature proglottids showed more zinc concentration than mature and gravid proglottids and fully grown cyst walls. Similarly, the youngest endogenous daughter cysts of Echinococcus granulosus contained more zinc in their walls than those of larger/older forms. Zinc was concentrated more in nematode eggs than in adult females.

Animals↗
PubMed1989

Simultaneous determination of fenamiphos, its sulphoxide and sulphone in water by high-performance liquid chromatography.

A method for the simultaneous determination of fenamiphos and its two metabolites, fenamiphos sulphoxide and fenamiphos sulphone, in water is described. The proposed method is based on the separation of the compounds on a silica gel column with ultraviolet detection and overcomes the problems of inadequate separation and possible decomposition associated with the gas-chromatographic determination of these compounds. The application of the method to groundwaters showed that a minimum detection level of the order of 10 micrograms l-1 could be achieved easily with pre-concentration of the samples on Sep-Pak C18 disposable cartridges.

Chromatography, High Pressure Liquid↗
PubMed1989

Polar/apolar chemical inducers of differentiation of transformed cells: strategies to improve therapeutic potential.

N,N'-Hexamethylenebisacetamide (HMBA) induces transformed cells to differentiate, accompanied by suppression of oncogenicity. Clinical trials have shown that HMBA can cause positive therapeutic responses in some cancer patients, but clinical efficacy may be limited, in part, by dose-related toxicity. Potential improvements in efficacy may be accomplished by changes in the chemical structure of inducing agents and by increasing the sensitivity of tumor cells to inducers of differentiation. We have previously described an approach to improving tumor cell responsiveness to inducing agents. Transformed cell lines that have acquired low levels of resistance to vincristine display a markedly increased sensitivity to HMBA. We now report on a series of hybrid polar/apolar compounds--some of which are as active as HMBA and several of which are significantly more active than HMBA in vitro--whose chemical structures make it likely that they have different pharmacokinetics. Vincristine-resistant murine erythroleukemia cells also are shown to have marked increased sensitivity to these hybrid polar/apolar compounds. Thus these findings suggest potentially useful strategies for the application of polar/apolar inducers of differentiation to the treatment of cancers. These studies also provide approaches to further understanding of the biological process of terminal differentiation.

Acetamides↗
PubMed1989

Gamma-monomethyl phosphate: a cap structure in spliceosomal U6 small nuclear RNA.

U6 small nuclear RNA (snRNA), a component of eukaryotic spliceosomes, is required for splicing of nuclear pre-mRNAs. Whereas trimethylguanosine cap-containing U sn-RNAs are transcribed by RNA polymerase II, the U6 RNA is transcribed by RNA polymerase III and contains a nonnucleotide cap structure on its 5' end. We characterized the cap structure of human U6 snRNA and show that the gamma phosphate of the 5' guanosine triphosphate is methylated. The mobilities of in vivo-modified gamma phosphate from the 5' end of HeLa U6 RNA were identical to the synthetic monomethyl phosphate (CH3-O-P) in two-dimensional chromatography and two-dimensional electrophoresis. The cap structure of U6 RNA is distinct from all other cap structures characterized thus far.

Chromatography, Thin Layer↗
PubMed1989

Effect of prolonged deprivation on attributional style.

The effects of prolonged deprivation and outcome on attributional style were examined in a 2 x 2 factorial design with two levels of deprivation (high and low) and two levels of outcome (good and bad). Indian subjects (N = 80) were selected on the basis of extreme scores on a prolonged deprivation scale; they provided an attributional style scale of good and bad outcome situations. High-deprived subjects attributed bad outcomes to more internal, stable, and global causes compared with low-deprived subjects. In addition, high-deprived subjects showed internal attributions of a stable and global type for both bad and good outcomes.

Adolescent↗
PubMed1989

Hypoxia and endotoxin induce macrophage-mediated suppression of fibroblast proliferation.

Cellular mechanisms and environmental factors contributing to wound failure following shock and wound contamination are unclear. The activation of macrophages by exposure to hypoxia (pO2 less than 20) and/or lipopolysaccharide (10 micrograms/ml) in vitro was investigated for its effect on macrophage regulation of fibroblast proliferation. The effect on fibroblast proliferation of conditioned medium from activated murine macrophages or co-culture with activated macrophages was tested by measuring 3T3 fibroblast incorporation of 3H-thymidine and culture DNA content. Unstimulated macrophages produced growth factors that increase fibroblast proliferation (proliferation index (PI) = 1.4 +/- 0.15, p less than 0.05 vs. control). Activation by hypoxia alone had little effect on macrophage regulation of fibroplasia (PI = 1.55 +/- 0.28, N.S. vs. unstimulated macrophages). LPS activated macrophages suppressed fibroplasia and the combination of hypoxia with LPS augmented the suppression (PI = 0.5 +/- 0.11, LPS alone, p less than 0.05 and 0.25 +/- 0.05, LPS + hypoxia, p less than 0.01). In addition, hypoxia + LPS treated co-cultures had reduced DNA contents, suggesting reduced cell numbers (12.5 +/- 2.6 micrograms vs. 8.2 +/- 2.0 micrograms). We screened several macrophage cytokines for their direct effect on 3T3 proliferation and found that mr-Tumor Necrosis Factor-alpha (150 units) also suppressed proliferation. Conditioned supernatants from LPS activated macrophages contained 12 +/- 2 units of mrTNF as measured by L929 cytolysis; however, this was significantly less than required to induce suppression of proliferation by direct addition. The regulatory role of the macrophage appears to be dependent on its level of activation. Activation by hypoxia and LPS altered macrophage regulation of fibroblast proliferation from stimulation to suppression.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗