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Biomedical subjects

A Goyal

Publications and source records attributed to A Goyal.

At least 91 records · Page 5Linked to original sources
PubMed1996

Association of glycolate oxidation with photosynthetic electron transport in plant and algal chloroplasts.

Photosynthetic carbon metabolism is initiated by ribulose-bisphosphate carboxylase/oxygenase (Rubisco), which uses both CO2 and O2 as substrates. One 2-phosphoglycolate (P-glycolate) molecule is produced for each O2 molecule fixed. P-glycolate has been considered to be metabolized exclusively via the oxidative photosynthetic carbon cycle. This paper reports an additional pathway for P-glycolate and glycolate metabolism in the chloroplasts. Light-dependent glycolate or P-glycolate oxidation by osmotically shocked chloroplasts from the algae Dunaliella or spinach leaves was measured by three electron acceptors, methyl viologen (MV), potassium ferricyanide, or dichloroindophenol. Glycolate oxidation was assayed with 3-(3,4)-dichlorophenyl)-1,1-dimethylurea (DCMU) as oxygen uptake in the presence of MV at a rate of 9 mol per mg of chlorophyll per h. Washed thylakoids from spinach leaves oxidized glycolate at a rate of 22 mol per mg of chlorophyll per h. This light-dependent oxidation was inhibited completely by SHAM, an inhibitor of quinone oxidoreductase, and 75% by 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), which inhibits electron transfer from plastoquinone to the cytochrome b6f complex. SHAM stimulated severalfold glycolate excretion by algal cells, Dunaliella or Chlamydomonas, and by isolated Dunaliella chloroplasts. Glycolate and P-glycolate were oxidized about equally well to glyoxylate and phosphate. On the basis of results of inhibitor action, the possible site which accepts electrons from glycolate or P-glycolate is a quinone after the DCMU site but before the DBMIB site. This glycolate oxidation is a light-dependent, SHAM-sensitive, glycolate-quinone oxidoreductase system that is associated with photosynthetic electron transport in the chloroplasts.

Journal Article↗
PubMed1996

Blunt trauma abdomen: a study of 63 cases.

63 cases of blunt abdominal trauma were studied. It was more common in males and in the age group 21-30 years. Majority of the injuries were due to automobile accidents. Commonly presenting feature was pain abdomen and vomiting. Abdominal paracentesis revealed haemoperitoneum in 40 cases which was subsequently confirmed on laparotomy in all the cases. 40 cases had no visible external injury but subsequent laparotomy revealed internal visceral injury in 29 cases. Exploratory laparotomy was carried out in 43 cases, remaining were treated conservatively. Liver was found to be the commonest organ injured. Post operative complications developed in 5 cases and deaths occurred in 7 cases mainly due to associated extra-abdominal injuries, poor pre-operative general condition, delayed diagnosis and management. We conclude that a multipronged approach towards early diagnosis and vigorous management should be adopted to reduce the morbidity and mortality in patients with blunt abdominal trauma.

Abdominal Injuries↗
PubMed1996

Isolation of NADH from Saccharomyces cerevisiae by ether permeabilization and its purification by affinity ultrafiltration.

Cells of Saccharomyces cerevisiae were permeabilized by ether for the isolation of coenzyme NADH. A 4-fold increase in the ether fraction to aqueous fraction resulted in the recovery of 80% of total NADH present in the cell. NADH was separated and purified by affinity ultrafiltration using yeast alcohol dehydrogenase as an affinity ligand. The binding characteristics of the enzyme and coenzyme were established at different pH and ionic strengths using gel filtration. The number of moles of NADH bound per mole of alcohol dehydrogenase (r) was found to be 5.7 at pH 8 and ionic strength (I) 0.1 M. The binary complex of NADH and alcohol dehydrogenase was cleaved by lowering the pH to 6.0. The crude cell permeate on purification by ultrafiltration with 2-fold dilution, gave NADH with an absorbance ratio (A260/A340) of 2.3 and overall yield of 68%. Alcohol dehydrogenase was recovered as retentate with 93% recovery and 15% loss in activity.

Alcohol Dehydrogenase↗
PubMed1995

A component of the chloroplastic protein import apparatus is targeted to the outer envelope membrane via a novel pathway.

A chloroplastic outer envelope membrane protein of 75 kDa (OEP75) was identified previously as a component of the protein import machinery. Here we provide additional evidence that OEP75 is a component of protein import, present the isolation of a cDNA clone encoding this protein, briefly describe its developmental expression and tissue specificity, and characterize its insertion into the outer envelope membrane. OEP75 was synthesized as a higher molecular weight precursor (prOEP75) which bound to isolated chloroplasts in an in vitro import assay and subsequently was processed to the mature form (mOEP75). During this import assay, two proteins intermediate in size between prOEP75 and mOEP75 were detected. One of these intermediates was also detected in chloroplast envelopes isolated from young pea leaves. Binding and processing of prOEP75 required ATP and one or more surface-exposed proteinaceous components, and was competed by prSSU, a stromal-targeted protein. We propose that the N-terminus of the prOEP75 transit peptide acts as a stromal-targeting domain and a central, hydrophobic region of this transit peptide acts as a stop-transfer domain. A complex route of insertion and processing of prOEP75 may exist to ensure high fidelity targeting of this import component.

Adenosine Triphosphate↗
PubMed1995

Inactivation of Leuconostoc mesenteroids NRRL B-512F dextransucrase by specific modification of lysine residues with pyridoxal-5'-phosphate.

Dextransucrase from Leuconostoc mesenteroides NRRL B-512F was inactivated by pyridoxal-5'-phosphate (PLP). The inactivation was reversible in as much as the loss of enzyme activity was completely reversed by prolonged dialysis. PLP-modified dextransucrase after reduction with sodium borohydride showed a characteristic fluorescence emission maximum at 397 nm when excited at 325 nm. The stoichiometric results indicated that four lysine residues are modified by PLP under the experimental conditions. These results established for the first time that lysine residues are essential for the activity of dextransucrase.

Binding Sites↗
PubMed1995

Involvement of a lysine residue in the inactivation of Leuconostoc mesenteroides NRRL B-512F dextransucrase by o-phthalaldehyde.

Leuconostoc mesenteroides NRRL B-512F dextransucrase was rapidly and irreversibly inactivated by o-phthalaldehyde. The dextransucrase-o-phthalaldehyde adduct showed a characteristic fluorescence maxima at 417 nm when excited at 337 nm. These results were consistent with the isoindole derivative formation in which the sulfhydryl group of cysteine and epsilon-amino group of lysine participate in the reaction. The stoichiometric determinations gave one isoindole derivative per enzyme molecule upon complete inactivation by o-phthalaldehyde. The enzyme showed no inhibition on treatment with thiol specific reagents. This indicated that cysteine is present in close proximity of the lysine and is involved in the isoindole derivative formation but is not participating in the catalysis. These results established for the first time that one lysine residue present at the active site is required for the activity of dextransucrase.

Enzyme Repression↗
PubMed1995

2,4,6-Trinitrobenzenesulphonic acid as a probe for lysine at the active site of dextransucrase from Leuconostoc mesenteroides NRRL B-512F.

Modification of Leuconostoc mesenteroides NRRL B-512F dextransucrase with 2,4,6-trinitrobenzenesulphonic acid (TNBS) at pH 5.2 and 30 degrees C resulted in the loss of enzyme activity. The kinetic profiles of inactivation showed that the reaction followed pseudo-first order reaction. Absorption spectra of TNBS modified enzyme gave characteristic maxima at 367 nm. The inactivation could not be reversed by dilution or dialysis. The substrate sucrose, provided protection to the enzyme against inactivation by TNBS, indicating that the essential residues are present at or near the active site. The stoichiometric results indicated that four mol of lysine are modified per mol of dextransucrase upon complete inactivation. However, more than 50% of the activity loss was accompanied by modification of 1 lysine residue. All these approaches suggested that one lysine residue present near or at the active site is essential for the enzymatic activity of dextransucrase.

Binding Sites↗
PubMed1995

Congenital cytomegalovirus infection in Shimla Hills, Himachal Pradesh, India.

We came across some cases clinically suggestive of intrauterine infection which were confirmed to be congenital cytomegalovirus infection. A clinical profile of these patients is presented. Intracranial calcification was not seen in any of these patients. Mental retardation was profound in all the patients and all had hepatomegaly. Uncommon findings encountered included hydrocephalus, patent ductus arteriosus and corneal opacities. Other clinical findings and investigation are also discussed.

Altitude↗
PubMed1995

Prevalence, group pattern, T pattern and seasonal variation of beta haemolytic streptococci in and around Shimla.

One hundred and seventy two strains of beta haemolytic streptococci were isolated from various clinical specimens over a period of one year. Group A was isolated in 69.70% and group C in 16.80 percent. Majority of the strains were isolated during winter season and only 21.00 percent in summer 93.30 percent strains were bacitracin sensitive and all were sensitive to penicillin. The most common T pattern among group A was found to be 5/11/12/27/44 followed by 3/13/B 3264.

Adolescent↗
PubMed1995

Typhoid hepatitis: report of two cases.

Early appearance of clinical jaundice is rare presentation in enteric fever. Although abnormal biochemical tests suggestive of hepatic involvement has already been suggested in 23-60 per cent of cases. The early hepatic changes have been attributed to generalised bacteraemia, persistence of hepatomegaly and hepatic lesion during pyrexial stage. But the typhoid hepatitis has been ignored as a clinical entity. In this report the importance of typhoid hepatitis and its clinical significance for the diagnosis of enteric fever is highlighted, particularly at places where viral hepatitis and hepatic amoebiasis are usually common and enteric fever is endemic.

Adolescent↗
PubMed1994

Five-year follow-up of microsurgical multiple internal thoracic artery grafts.

In a consecutive series of 143 patients requiring multiple coronary artery bypass grafts, 317 of 441 anastomoses (72%) were constructed from internal thoracic arteries. Of these 143 patients, 103 had bilateral, 51 sequential, and 49 free internal thoracic artery grafts. When compared with an earlier series of 494 patients who underwent only one internal thoracic artery anastomosis, the surgical morbidity and mortality were not increased, but, during 5 years of follow-up, the incidences of postoperative angina and myocardial infarction were found to decrease significantly--32.5% versus 10.5% (p < 0.001) and 5.7% versus 1.4% (p < 0.03), respectively. We conclude that, for patients with multivessel disease, multiple internal thoracic artery grafts confer better protection from the clinical manifestations of ischemic heart disease than does one internal thoracic artery graft. The use of high magnification (8 to 12x, surgical microscope) was essential to the success of this method.

Coronary Disease↗
PubMed1994

Relevance of platelet serotonergic mechanisms in pregnancy induced hypertension.

Platelet functions are becoming the useful tool for delineating the etiology of pregnancy induced hypertension. Electronmicroscopic studies, efflux and content of 5-HT in platelets and platelet aggregation responses towards various aggregating agents have been measured in 25 normotensive pregnant subjects and 31 PIH subjects. Marked decrease changes have been noted in aggregation parameters with transformation from discoid to "spiny sphere" of platelets with long pseudopods along with prolonged time for spontaneous aggregation by platelets in PIH. Serotonin release from platelets was decreased and reserpine-induced release-reaction showed enhanced kinetics in PIH. Platelet serotonin content was raised and was inversely related to platelet count with severity of syndrome. Hence, a check and balance for platelet activation and aggregation in PIH might be crucial in the development of PIH.

Adolescent↗