Biomedical subjects
Publications and source records attributed to N Malik.
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The incidence of renal vein thrombosis (RVT) and other thrombo-embolic phenomena was evaluated in 44 unselected patients with nephrotic syndrome. Renal vein thrombosis was demonstrated by selective renal venography in 10 patients and at post-mortem in one. Extension of the thrombus from the renal veins into the inferior vena cava was seen in 3 patients. Evidence of thrombo-embolism elsewhere in the body was seen in the form of thrombophlebitis in the lower extremities in 4 patients (9.1%), pulmonary embolism in 3 (6.8%) and myocardial infarction in one (2.3%). Of the 11 patients with RVT, renal histology showed membranous glomerulonephritis in 3, minimal change nephritis in 5, membrano-proliferative in one and focal and diffuse proliferative glomerulonephritis in one patient each. The characteristics clinical findings such as gross haematuria and flank pain were noted in only 3 patients with RVT. No significant difference could be detected between the plasma fibrinogen, serum cholesterol, beta-lipoprotein, triglycerides and phospholipid concentration of those who showed RVT and the remainder in whom RVT was not demonstrated. The possible mechanisms involved in the pathogenesis of RVT in nephrotic syndrome are discussed.
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Two patients with appendicovesical fistulae are described. Both presented with gastrointestinal and urinary symptoms. Biochemical examination showed hypokalaemic hyperchloraemic metabolic acidosis; radiographic investigations showed a vesical stone and a communication between the bladder and the bowel. The findings at operation suggested that the fistulae may have arisen as complications of previous appendicitis. The diagnosis of appendicovesical fistulae may be difficult but should be considered in the presence of hypokalaemic hyperchloraemic metabolic acidosis and vesical stones.
Analytical procedures based on filtration of homogenates through membrane filters, and particularly hydrophobic grid-membrane filters (HGMF), offer definite improvements in the enumeration of Escherichia coli and coliforms in foods. Whereas the counted specimen in pour plates may not usually be greater than 0.1 g, up to 1.0 g of ground beef, green beans, potato, cod, strawberries, or grapes could be filtered and counted on HGMF. Greatly improved limit of detection, reduced interference by noncoliforms, and complete removal of growth inhibitors such as polyphenols were demonstrated for HGMF, using violet red bile and mFC agars. In addition, counting on HGMF eliminated a false-positive reaction caused by sucrose in ice cream.
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Rat intestinal alkaline phosphatase is an heterogeneous glycoprotein that contains three protein sub-forms separable by electrophoresis. The molecular weight for the glycoprotein (i.e. the average for the three sub-forms) is 157 000-160 000. Three protein sub-forms are detectable on sodium dodecyl sulphate-polyacrylamide gel electrophoresis that migrate at rates corresponding with molecular weights of 64 000, 79 000 and 92 000. Treatment of native alkaline phosphatase with 6 M guanidine - HC1 or buffer at pH 3.0 results in a product with a molecular weight of 78 000 and 70 000, respectively. Thus it is concluded that each of the three sub-forms is a dimer of identical or closely similar subunits. Limited proteolysis results in the production of new enzymically active sub-forms separable by electrophoresis. Using a bacterial protease it is possible to convert intestinal alkaline phosphatase into a form with a molecular weight of 132 000 without causing any significant change in kinetic properties. Electrophoresis of this new form on sodium dodecyl sulphate polyacrylamide gel suggests that it is composed of 66 000-dalton subunits. The native enzyme contains at least 20% by weight of carbohydrate that probably contributes to microheterogeneity of a second degree superimposed on that stemming from the presence of three protein sub-forms. Treatment with various glycosidases has no effect on electrophoretic behaviour, however. It is suggested that the three sub-forms possibly represent different stages of a maturation process that operates by limited proteolysis of a single parent protein.
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A stable Chinese hamster ovary (CHO) cell line producing high levels of human oncostatin M (OM) was generated by transfecting a heterologous gene coding for the protein. This novel construct was comprised of the gene for the transforming growth factor-beta 1 (TGF-beta 1) signal peptide fused to the gene for mature human OM. Amplification with methotrexate produced milligram quantities of this recombinant OM, which was processed correctly, glycosylated, and found to have biological functions similar to those of natural OM.
The surface properties of stents can be modified by coating them, for example with a polymer. Phosphorylcoline (PC) is the major component of the outer layer of the cell membrane. The haemo- and biocompatibility of a PC-containing polymer is thus based on biomimicry, and has been confirmed by several experiments showing much reduced thrombogenicity of PC-coated surfaces, and porcine coronary artery implants showing no sign of adverse effect. Clinical experience with the PC-coated BiodivYsio appears favourable. The PC coating can be tailored for take up and controlled elution of various drugs for stent-based local delivery, a property which is being actively explored.
Over a 16-year period, 205 patients with hypertension were shown to have a renovascular aetiology. Of these, 125 (61 per cent) had Takayasu's arteritis, 58 (28.3 per cent) had fibromuscular dysplasia, 16 (7.8 per cent) had atherosclerosis, five (2.4 per cent) had polyarteritis nodosa and one (0.5 per cent) had renal artery aneurysm. Among patients with Takayasu's arteritis, males were affected as commonly as females. The mean age of these patients at the time of detection was 26.8 +/- 8.6 years (range 5-52 years). Type I arteritis was seen in nine (7.2 per cent), Type II in 40 (32 per cent) and Type III in 76 (60.8 per cent) patients. The abdominal aorta was involved in 117 (93.3 per cent) patients. Takayasu's arteritis was associated with ulcerative colitis in two patients and with renal amyloidosis and focal segmental glomerulosclerosis with a nephrotic syndrome in one patient each. Surgical intervention consisting of bypass procedures, autotransplantation or nephrectomy was performed in 17 (13.6 per cent) and angioplasty in nine (7.2 per cent) patients. Cure and improvement in blood pressure was observed in 82.4 per cent and 77.8 per cent respectively. Adequate control of blood pressure was achieved with drugs only in 22 (22.2 per cent) patients. A definite cause and effect relationship could not be established between any infective or immunological disorder and Takayasu's arteritis. Takayasu's arteritis is a far more common cause of renovascular hypertension in Indian population than fibromuscular dysplasia or atherosclerosis, which are more common in the western population.
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