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Biomedical subjects

S Khwaja

Publications and source records attributed to S Khwaja.

12 recordsLinked to original sources
PubMed1992

Modification of plasma proteins by cigarette smoke as measured by protein carbonyl formation.

Exposure of human plasma to gas-phase (but not to whole) cigarette smoke (CS) produces oxidative damage to lipids [Frei, Forte, Ames & Cross (1991) Biochem. J. 277, 133-138], which is prevented by ascorbic acid. The ability of CS to induce protein damage was measured by the carbonyl assay and by loss of enzyme activity and protein -SH groups. Both whole and gas-phase CS caused formation of carbonyls in human plasma, which was partially inhibited by GSH but not by ascorbic acid or metal-ion-chelating agents. Isolated albumin exposed to CS showed much faster carbonyl formation (per unit protein) than did whole plasma; damage to isolated albumin was partially prevented by chelating agents. Isolated creatine kinase (CK) lost activity upon exposure to CS much faster than did CK in plasma. Direct addition to plasma of mixtures of some or all of the aldehydes reported to be present in CS caused protein carbonyl formation and inactivation of CK, but neither occurred to the extent produced by CS exposure.

Adult↗
PubMed1992

Antiradical effects in L-propionyl carnitine protection of the heart against ischemia-reperfusion injury: the possible role of iron chelation.

L-Propionyl carnitine has been shown to improve the heart's mechanical recovery and other metabolic parameters after ischemia-reperfusion. However, the mechanism of protection is unknown. The two dominating hypotheses are: (i) L-propionyl carnitine can serve as an energy source for heart muscle cells by being enzymatically converted to propionyl-CoA and subsequently utilized in the Krebs cycle (a metabolic hypothesis), and (ii) it can act as an antiradical agent, protecting myocardial cells from oxidative damage (a free radical hypothesis). To test the two possible pathways, we compared the protection afforded to the ischemia-reperfused hearts by L-propionyl carnitine and its optical isomer, D-propionyl carnitine. The latter cannot be enzymatically utilized as an energy source. The Langendorff perfusion technique was used and the hearts were subjected to 40 min of ischemia and 20 min of reperfusion. In analysis of ischemia-reperfused hearts, a strong correlation was found between the recovery of mechanical function and the presence of protein oxidation products (protein carbonyls). Both propionyl carnitines efficiently prevented protein oxidation but L-propionyl carnitine-perfused hearts had two times greater left ventricular developed pressure. The results indicate that both metabolic and antiradical pathway are involved in the protective mechanism of L-propionyl carnitine. To obtain a better insight of the antiradical mechanism of L-propionyl carnitine, we compared the ability of L- and D-propionyl carnitines, L-carnitine, and deferoxamine to interact with: (i) peroxyl radicals, (ii) oxygen radicals, and (iii) iron. We found that none of the carnitine derivatives were able to scavenge peroxyl radicals or superoxide radicals. L- and D-propionyl carnitine and deferoxamine (not L-carnitine) suppressed hydroxyl radical production in the Fenton system, probably by chelating the iron required for the generation of hydroxyl radicals. We suggest that L-propionyl carnitine protects the heart by a dual mechanism: it is an efficient fuel source and an antiradical agent.

Animals↗
PubMed1992

Thioctic acid protects against ischemia-reperfusion injury in the isolated perfused Langendorff heart.

Antioxidant properties of thioctic and dihydrolipoic acid have been demonstrated in membranes and low density lipoproteins (LDL) in vitro. In vivo studies with dietary supplementation of thioctic acid to rats showed that it can also protect tissues against oxidative damage. Presumably, this action is due to a thioctic acid dihydrolipoic acid (TA/DHLA) coupled antioxidant mechanism, which enhances the activity of other antioxidants (i.e. ascorbate, alpha-tocopherol) by regenerating them from their radical form. In the present study, thioctic acid proved to protect against ischemia/reperfusion injury to Langendorff perfused hearts. Hearts isolated from rats fed thioctic acid and subjected to ischemia exhibited better mechanical recovery (left ventricular developed pressure) after reperfusion and lower lactate dehydrogenase leakage. Thioctic acid supplementation also decreased the appearance of fluorescent lipid peroxidation products after ischemia/reperfusion, lowered the rate of 2,2'-azobis-(2,4-dimethylvaleronitrile) (AMVN) induced lipid peroxidation in heart homogenates, and prevented the loss of alpha-tocopherol. The total sulfhydryl group content in thioctic acid fed animals was higher and the decrease due to ischemia-reperfusion was not as marked in this group as observed in the control. These results show that dietary supplementation with thioctic acid in vivo provides protection against ischemia/reperfusion injury in the Langendorff heart model.

Animals↗
PubMed1991

Primary hyperparathyroidism: presentation and management.

164 hypercalcemic patients were examined to determine the co-relation, frequency and mode of presentation of primary hyperparathyroidism. Primary hyperparathyroidism was diagnosed in 11 patients (6.7%). All of them presented late with renal and bony complications. The incidence of primary hyperparathyroidism appears to be lower than that of the western countries, and the introduction of routine serum calcium estimates can be expected to yield more cases of primary hyperparathyroidism especially asymptomatic cases.

Adult↗
PubMed1989

Congenital intrinsic duodenal obstruction: problems in the diagnosis and management.

Nineteen infants with intrinsic duodenal obstruction are analyzed. Atresia was the most common lesion. An exceptionally high rate of associated anomalies (73.7%) were present; Down's syndrome, the single most common anomaly, was seen in 47% of the infants. In seven infants, the diagnosis was delayed and in another three it was made intraoperatively while establishing a gastrostomy for esophageal atresia. Three infants died without operation because of gross prematurity and multiple anomalies. Of the 16 operated on, three died, one due to peritonitis and the other two because of metabolic derangements. Of the various operative procedures used, no significant difference was found in the final outcome of treatment. A schematic approach to the diagnosis and management is proposed.

Anastomosis, Surgical↗
PubMedDate not supplied

Splenectomy for hematological disorders in the Eastern Province of Saudi Arabia.

Splenomegaly is a common clinical disorder in the Kingdom of Saudi Arabia. Its aetiology is variable and includes portal hypertension due to schistosomal periportal hepatic fibrosis, haemoglobinopathies and lymphoproliferative disorders. At King Fahd Hospital of the University, Al-Khobar in the Eastern Province of the Kingdom, splenectomy is performed frequently for various reasons on patients drawn from all the Provinces. This is a report of 104 patients (age range eight months to 65 years) who underwent splenectomy between 1982 and 1987. We reviewed the indications, operative findings, outcome, and complications of the procedure. Patients with hypersplenism formed the largest group (50%) subjected to splenectomy followed by those suffering from the haemoglobinopathies. Chest infection as the most common complication and it mainly affected patients with portal hypertension. Post-operative septicaemia occurred in four cases within six months from the date of splenectomy.

Adolescent↗
PubMedDate not supplied

Fracture of the penis: surgical management.

Fracture of the penis is a rare injury, only 135 patients having been reported by 1985. Our recent experience with six patients who underwent emergency surgery, has been documented. The results of treatment were excellent with complete recovery of function. The study recommends operative management as the treatment of choice.

Adult↗