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Biomedical subjects

A K Grover

Publications and source records attributed to A K Grover.

At least 73 records · Page 4Linked to original sources
PubMed1991

Expression of isoforms of internal Ca2+ pump in cardiac, smooth muscle and non-muscle tissues.

Smooth muscle and several non-muscle tissues contain mRNA for an alternative splice of the mRNA for the cardiac sarcoplasmic reticulum (SR) Ca,Mg-ATPase. Based on amino acid composition deduced from cDNA sequences the cardiac isoform (Ic) is 110 kDa while the smooth muscle and the non-muscle isoform (Is) is 115 kDa. This prediction in their molecular masses was tested at the protein level in rabbit stomach, aorta, uterus and vas deferens smooth muscles; stomach mucosa, brain, liver, kidney and heart. The major species of the acylphosphates formed in the presence of Ca2+ and electrophoresed in acid SDS-acrylamide gels were 5 kDa smaller for the heart (Ic) than those for all the other tissues (Is). The size difference was also confirmed in Western blots using a monoclonal antibody which binds to both Is and Ic. Thus consistent with the mRNA splices for the internal Ca2+ pumps previously reported to be present in these tissues, rabbit heart expresses predominantly the Ca2+ pump protein Ic and the various smooth muscle, mucosa, brain, liver and kidney express mainly the isoform Is.

Animals↗
PubMed1991

Serum beta-2 microglobulin and C-reactive protein levels in acute adenovirus conjunctivitis.

Serum beta-2 microglobulin and C-reactive protein levels were measured in 52 patients with acute adenovirus conjunctivitis and 58 healthy subjects, by ELISA technique. Serum beta-2 microglobulin levels were found to be significantly increased while there was no change in C-reactive protein levels. Serum beta-2 microglobulin levels closely paralleled the severity of the disease. The increased beta-2 microglobulin level in serum showed a significant fall to normal level on clinical improvement. There was no difference in the serum beta-2 microglobulin levels in virus-isolation positive and negative patients.

Acute Disease↗
PubMed1991

Serum alpha-1 acid glycoprotein levels in acute idiopathic anterior uveitis.

Serum alpha-1 acid glycoprotein levels were measured in 56 patients with acute idiopathic anterior uveitis and 42 healthy subjects by a radial immunodiffusion method. The levels were found to be increased significantly in moderate and severe types of uveitis; they were normal in mild type. Serum alpha-1 acid glycoprotein levels closely paralleled the severity of the disease. The serum levels of this protein returned to normal after clinical improvement.

Acute Disease↗
PubMed1990

Abundance of sarcoplasmic reticulum calcium pump isoforms in stomach and cardiac muscles.

Rabbit stomach smooth muscle contains mRNA for an internal Ca2+ pump identical in sequence to that reported for rabbit uterus [Lytton, Zarain-Herzberg, Periasamy & MacLennan (198) J. Biol. Chem. 264, 7059-7065]. This is an alternatively spliced form (Is) of the cardiac muscle sarcoplasmic reticulum Ca2+ pump (Ic). The splicing results in replacement of the last 4 amino acids (Ala-Ile-Leu-Glu) present in Ic by 49 amino acids and by a different 3'-non-coding region. Using cDNA probes against the conserved and the alternatively spliced regions, we determined that poly(A+) RNA isolated from rabbit stomach smooth muscle did not contain any transcripts for Ic. The poly(A+) RNA from cardiac muscle contained transcripts mostly for Ic, but also some for Is. The abundance of the Ca2(+)-pump transcripts as measured by the binding of a cDNA probe against the conserved region to poly(A+) RNA was 6-8 times higher in cardiac than in smooth muscle. The amount of the corresponding pump protein, measured using two antibodies, was 60-80 times higher in cardiac membranes than in smooth muscle membranes. Thus the protein-to-transcript level was approx. 10-fold higher in the cardiac muscle. We conclude that the regulation of the abundance of this protein occurs at steps leading to the formation of the mature mRNA for the two splices, which may differ in their translation efficiency.

Animals↗
PubMed1990

Splenic abscess.

We report a splenic abscess in an elderly diabetic female. Awareness of the disease is emphasised.

Abscess↗
PubMed1989

Protection of Ca pump of coronary artery against inactivation by superoxide radical.

Superoxide radicals inactivate endoplasmic reticular (ER) Ca2+ pump in membranes isolated from smooth muscle of pig right coronary artery [Am. J. Physiol. 255 (Cell Physiol. 24): C297-C303, 1988]. We report on protective mechanisms against such inactivation. This tissue contained superoxide dismutase (SOD) and catalase. SOD was distributed primarily in cytosolic fraction, was cyanide sensitive, and was also present in mitochondrial fraction, and approximately 25% of this was cyanide insensitive. Catalase was distributed mainly in mitochondrial fraction and did not protect against inactivation of ER Ca2+ pump by superoxide radicals generated using xanthine plus xanthine oxidase. However, cytosolic fraction protected against this inactivation by two mechanisms: 1) DTT carried over from homogenization medium and 2) its intrinsic SOD content. Soluble fraction was concentrated, dialyzed to remove 1,4-dithiothreitol (DTT), lyophilized, and suspended in a small volume of DTT-free buffer. It still protected against superoxide inactivation of Ca2+ pump. On Sephacryl-300 gel chromatography, protecting activity comigrated with SOD. DTT protected against inactivation, but glutathione and cysteine protected only partially. Neither sulfhydryl agents nor SOD could reverse the inactivation process. Ca2+ pump activity was abolished by dithionitrobenzoate and p-chloromercuric benzoate. Superoxide may inactivate ER Ca2+ pump by irreversibly modifying key sulfhydryl group(s) on pump molecule and SOD in coronary artery smooth muscle may partially protect against this inactivation.

Animals↗
PubMed1988

Monoclonal antibody against an epitope on the cytoplasmic aspect of the plasma membrane calcium pump.

Monoclonal antibody PM4A2B was prepared by immunizing mice with calmodulin affinity purified Ca2+-Mg2+-adenosine triphosphatase from rabbit erythrocytes and screening the clones with a plasma membrane-enriched fraction (F1) from rabbit stomach smooth muscle. On Western blots, PM4A2B reacted with F1 and with ghosts, right-side-out vesicles, and inside-out vesicles prepared from erythrocytes giving one major band at 130 kDa and minor lower molecular weight bands whose intensity increased on freezing and thawing the membranes. On enzyme-linked immunosorbent assay, PM4A2B reacted with inside-out vesicles, but not with the right-side-out vesicles or ghosts prepared from erythrocytes. It activated the ATP-dependent Ca2+ uptake by F1 and by the inside-out vesicles prepared from the erythrocytes. PM4A2B should be useful in determining membrane sidedness as well as in investigating the mechanism of the sarcolemmal Ca2+ pump.

Animals↗
PubMed1988

Evidence for a Na+/H+ antiport in stomach smooth muscle cells.

Single smooth muscle cells were isolated from circular muscle of the canine gastric corpus by collagenase incubation. Cytoplasmic pH (pHi) of these cells was measured fluorometrically using the trapped dye 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein. Cells were examined for their Na+/H+ exchange activity after intracellular acidification. Cells acid-loaded by propionate exposure, the NH4+ prepulse technique or suspension in a Na+-depleted medium regained almost normal pHi upon exposure to a Na+ medium. The Na+-dependent alkalinization was amiloride sensitive. As well, addition of amiloride to cells suspended in a Na+ medium caused a concurrent decrease in pHi. The study indicates that a Na+/H+ antiport is present in these smooth muscle cells.

Amiloride↗
PubMed1988

Effect of superoxide radical on Ca2+ pumps of coronary artery.

The effect of superoxide radical on the azide-insensitive ATP-dependent Ca2+-transport by a plasma membrane (PM)-enriched fraction (F2) and an endoplasmic reticulum (ER)-enriched fraction (F3) isolated from pig coronary artery was examined using xanthine oxidase plus xanthine to generate superoxide ions. A preincubation with xanthine oxidase plus xanthine at 37 degrees C preferentially inactivated the oxalate-stimulated Ca2+ uptake by the F3 fraction rather than the phosphate-stimulated uptake by the F2 fraction, indicating that the Ca2+ pump in the ER was more susceptible to this free radical. The inactivation of the Ca2+ uptake depended on the concentrations of xanthine oxidase and xanthine in the preincubation mixture as well as on the preincubation time. Furthermore, the inclusion of superoxide dismutase in the preincubation mixture prevented the inactivation. Thus the inactivation was caused by superoxide radical. Preincubation with xanthine oxidase plus xanthine, however, altered the half-life of efflux of Ca2+ from these vesicles only marginally. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the F3 fraction showed formation of a Ca2+-dependent acid stable phosphoenzyme at 0 degree C predominantly at a protein band corresponding to 100 kDa. The level of the 100-kDa acylphosphate intermediate was inhibited in parallel with the inhibition of the Ca2+ uptake by preincubation with xanthine oxidase plus xanthine. We conclude that superoxide radical inactivates the ER Ca2+ transport by lowering the level of the phosphoenzyme.

Animals↗
PubMed1987

Impurities in commercial xanthine oxidase inhibit Ca pump and interfere in contractility of pig coronary artery.

Commercial, but not pure, preparations of xanthine oxidase in the absence of an aldehyde or xanthine were observed to inhibit Ca-uptake by the subcellular membranes isolated from the smooth muscle of the pig coronary artery. This inhibition was not due to xanthine oxidase but a contaminant in the preparation. The commercial preparation caused a greater relaxation of the PGF2 alpha contracted coronary artery than the pure enzyme. The tissues treated with the commercial xanthine oxidase partially lost the ability to contract subsequently to PGF2 alpha.

Animals↗
PubMed1987

Characterization and solubilization of the nitrendipine binding protein from canine small intestinal circular smooth muscle.

The binding of nitrendipine, a calcium channel blocking agent, to the microsomes prepared from canine small intestinal circular smooth muscle was characterized. The binding of this 1,4-dihydropyridine to the membrane was reversible, saturable and of high affinity with a dissociation constant of 0.28 nM and a maximal binding of 91 fmol/mg microsomal protein. The binding occurred with an association rate constant of 0.094 nM-1 min-1 and dissociated at the rate of 0.0498 min-1. These rate constants gave a value of 0.52 nM for the dissociation constant of the binding. The binding was inhibited in a competitive fashion by other dihydropyridines (nifedipine, nimodipine, nisoldipine, PN200-110) with inhibition constants in the range of 0.1 to 1.0 nM. The binding was also inhibited by verapamil and D-600 but only at much higher concentrations. Diltiazem increased the nitrendipine binding to the membranes. The nitrendipine binding protein was solubilized using the detergent 3-[(3-cholamidopropyl)dimethyl-ammonio]-1-propanesulfonate (CHAPS). The solubilized material bound nitrendipine with a dissociation constant of 0.51 nM giving maximal binding of 70 fmol/mg protein. The binding of the solubilized material resembled the membrane bound material in inhibition by the dihydropyridines, verapamil and D-600 and in the increase by diltiazem. Thus we have solubilized the nitrendipine binding protein without changing its binding properties substantially.

Animals↗
PubMed1987

Aspergillus endophthalmitis.

A case is reported of bilateral aspergillus endophthalmitis in an infant without any detectable systemic predisposition or focus of infection. The patient is the youngest recorded case of endogenous aspergillus endophthalmitis so far, with an onset of symptoms at the age of 15 days. After histopathological confirmation of the aetiology by enucleation of the atrophic eye, systemic amphotericin B therapy was instituted with excellent results in the fellow eye. This is the first recorded instance of a complete clinical cure in aspergillus ocular disease on systemic amphotericin B therapy alone.

Ampicillin↗
PubMed1986

Calcium binding proteins in smooth muscle plasma membrane.

Rat myometrium plasma membrane showed a number of 45Ca-binding proteins as identified by gel electrophoresis. An attempt was made to identify these either by studying the inhibition of this binding by several ions or by studying binding of these proteins to calmodulin, A9 an antibody against skeletal muscle Ca-binding proteins and Stains-all. On the basis of the molecular weight, calmodulin binding and La-sensitivity of Ca-binding, the Ca-binding protein at 137 +/- 2 kDa has been identified as the Ca-pump. This protein as judged from Coomassie blue staining forms a very small percentage of the proteins present in the plasma membrane.

Animals↗
PubMed1986

High affinity Ca-binding to smooth muscle plasma membrane: inhibition by cations.

The effects of Mg2+, Na+ and K+ on the pH-dependent high affinity passive Ca-binding to sarcolemmal enriched membrane fractions from the smooth muscles of rat myometrium and gastric fundus were examined at 1 uM Ca2+-concentration. For the myometrial plasma membranes, these ions inhibited the passive Ca-binding with the following IC50 values: Mg2+: 1.75 mM; Na+: 19 mM; K+: 233 mM. Similarly, for the gastric fundus membranes, the IC50 values were Mg2+:1.6 mM, Na+:46 mM and K+:67 mM.

Animals↗
PubMed1986

Subcellular membrane properties in vascular and non-vascular smooth muscles of Dahl hypertensive rats.

Subcellular membrane fractions were isolated from mesenteric arteries and vas deferens of salt-resistant and salt-sensitive Dahl rats on low-salt (0.4% NaCl) high-salt (8.0% NaCl) diets. Only the salt-sensitive Dahl rats on the high-salt diet developed sustained high blood pressure (BP) after 5 weeks of the high-salt diet. Protein contents, membrane associated enzyme activities, calcium ion (Ca2+) binding and ATP-dependent CA2+ transport were compared in fractions isolated from all four groups. No obvious changes were observed, except for minor enhancement in magnesium ion (Mg2+)- and CA2+ ATPase activities of mesenteric arterial membranes isolated from salt-sensitive Dahl rats on high-salt diet compared to those from other groups of rats. The membrane fractions from vas deferens of salt-sensitive Dahl rats on the high-salt diet, on the other hand, showed decreased ATP-dependent Ca2+ transport compared to those from salt-sensitive Dahl rats on the low-salt diet. No difference was observed in membrane fractions isolated from salt-resistant Dahl rats on high-salt diet compared to those on low-salt diet. The significance of these observations are discussed in relation to the findings previously obtained from corresponding smooth muscle tissues of spontaneous hypertensive rats (SHR).

Adenosine Triphosphate↗