Biomedical subjects
Publications and source records attributed to R Saxena.
Platelet aggregation with collagen, ADP and sodium arachidonate was significantly inhibited by 0.48 and 0.24 mg/ml of diltiazem but no significant effect occurred with 0.024 mg/ml of diltiazem. It is suggested that the antiplatelet property of diltiazem may be utilized in clinical setting and diltiazem may be tried synergistically with other antiplatelet drugs.
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It has recently been demonstrated that many patients with various types of glomerulonephritis have antibodies to the 6M guanidine-HCl extract of glomerular basement membrane (Bygren et al, Nephrol Dial Transplant 4:254-261, 1989). In the present study a 150 K protein was isolated from the guanidine extract of bovine glomerular basement membrane utilizing ion exchange and gel filtration chromatographic procedures. Amino acid analysis and size of the isolated protein revealed similarity to that of entactin/nidogen. The identity of this protein as entactin/nidogen was further suggested by its precipitation with two different antibodies in a radioimmunoassay and by its reaction with four different antibodies in a sandwich ELISA. Inhibition of the antibodies to 150 K by bovine entactin, which was isolated separately and sequenced for amino acids, confirmed the identity of the 150 K protein as entactin/nidogen. Furthermore, it was shown that about one third of those patients who show antibodies to the crude guanidine extract have circulating antibodies directed against entactin. This was further confirmed by the competitive inhibition of antibodies to the crude guanidine extract in one of the positive serum by entactin in an ELISA inhibition and by immunoblotting experiments. These observations propose entactin as a possible non-Goodpasture glomerular basement membrane antigen that could be involved in the pathogenesis of certain forms of autoimmune glomerulonephritis (non-Goodpasture anti-GBM glomerulonephritis) in man. Most of these patients have a granular pattern of the immunoglobulin deposition along the glomerular basement membrane. This suggests the possibility that anti-GBM glomerulonephritis in human beings can have non-linear immunoglobulin deposits along the GBM.
Kidney involvement by Non-Hodgkin's lymphoma is very common microscopically but rarely a cause of uraemia even when the parenchymatous involvement is considerable. Renal failure in cases of lymphoma is secondary to ureteral obstruction, hypercalcaemia, urate nephropathy, gammopathy or immunologically mediated nephrosis. This is a case where the patient presented to the ophthalmic O.P.D. with blurring of vision and admitted with full blown uraemia. He could not be saved and at autopsy, a gastrointestinal lymphoma was found in the caecum. His uraemia was due to massive parenchymatous involvement of the kidney, there being no ureteral obstruction, hypercalcaemia, urate or immunologically mediated nephropathy. Very few cases are reported in literature with such a presentation.
A simple and inexpensive micromethod based on methaemoglobin reduction technique (MRT) for screening of glucose-6 phosphate dehydrogenase deficiency has been studied using reagent-impregnated curvettes incubated in a makeshift waterbath. The cuvettes shelf life has been tested upto nine months. As the test can be done with finger prick blood, it promises to be more acceptable in the field. The sensitivity of this is similar to classical MRT.
The results of highly selective vagotomy in 174 Indian patients have been analysed. Compared to other procedures on the stomach, HSV has a definite advantage both on long term as well as on short term basis. HSV has therefore become the procedure of choice in the treatment of duodenal ulcer disease provided the expertise is available locally. HSV has also been used now in the treatment of ulcer complications and benign gastric ulcer disease.
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A rapid ELISA for the detection of circulating anti-glomerular basement membrane antibodies in Goodpasture syndrome is described. The specificity of the test was shown to be highly dependent on the antigens used. Using the purified Goodpasture antigen it was possible to shorten the incubation times to 10 min in a routine assay using alkaline phosphatase-labeled second antibodies and the total assay was complete in 30 min. 200 reference sera, 500 sera from patients with various types of glomerulonephritis and 32 sera from patients with Goodpasture syndrome were analyzed by this rapid assay. The assay was able to discriminate between Goodpasture syndrome and other forms of glomerulonephritis. Using enzyme amplification it was possible to further shorten the incubation times to 1 min and the total time of the assay to 6 min.
We describe a case of rheumatic tricuspid stenosis without involvement of the mitral valve. Rheumatic disease of the tricuspid valve is very rare in the absence of concomitant mitral valvar disease. We suggest that the closing pressure at the valve is not the only factor governing localization of the rheumatic process.
Total esophageal exclusion and substernal gastric bypass were performed on eight patients with unresectable carcinoma of the thoracic esophagus who had received radiotherapy as the primary treatment. One patient died postoperatively. Three patients developed cervical anastomotic leaks which settled with conservative treatment. Average survival after the surgery was eight months and all seven survivors were able to eat normally. The simplicity and effectiveness of the operation have been emphasized.
A case of Tuberculoid leprosy who had taken irregular treatment for five years and had thickened ulnar nerve which on radiological examination showed calcification, is reported.
Coagulation profile was studied in 55 patients of systemic lupus erythematosus (SLE). Abnormal kaolin clotting time (KCT) was observed in fewer patients (12.9%) as compared to abnormal Russel's viper venom time (RVVT, 20.4%) or activated partial thromboplastin time (APTT, 32.7%). Prolonged prothrombin time (PT), observed in 7.3 per cent patients was not found to be a sensitive test for lupus anticoagulant (LAC). The correction of RVVT and KCT on addition of inosithin suggested a deficiency of platelet lipid factor in these patients. The initial value of uncorrected KCT in patient's plasma did not correlate with the amount of inosithin required for neutralisation. Occurrence of thromboembolic events was significantly associated with prolonged KCT. No other clinical feature showed significant association with any coagulation abnormality.
A thirty year female patient presented with features of thyrotoxicosis, myopathy and cervical myelopathy of one year duration. Her cervical metrizamide myelogram was normal. On antithyroid therapy muscle weakness and features of myelopathy improved over three months follow up.
Studies on ultrastructure of drug-resistant strains of Plasmodium berghei have been mostly restricted to the experimentally selected chloroquine and pyrimethamine resistant strains. Study of the morphology of mefloquine and quinine resistant strain of P. berghei has been carried out to demonstrate some differences between normal and drug-resistant strains. The main differences are concerned with a complex physiological process i.e., food ingestion and digestion. E.M. studies reveal that in the sensitive strain of P. berghei the trophozoites possess numerous rod-shaped malarial pigment particles which lie within a vesicle. In the trophozoites of resistant parasites the malarial pigment particles are rarely visible. Trophozoites of the sensitive strain have only one large food vacuole while the trophozoite of the resistant parasite contains 2-3 smaller vacuoles.
The specificity of kidney-bound antibodies in Goodpasture's syndrome was studied and compared with the specificity of circulating anti-glomerular basement membrane (GBM) antibodies. Antibodies were eluted from kidneys of two patients with Goodpasture's syndrome and from one normal human kidney. Their specificity was studied by indirect immunofluorescence microscopy, ELISA and immunoblotting using purified GBM components as antigens. It was shown that the reactivity of the eluted antibodies was very similar to those of the circulating anti-GBM antibodies. Both showed major reactivity against the M2 subunit of the globular domain of collagen IV. Competitive inhibition of the binding of 125I-labelled serum antibodies from a patient with Goodpasture's syndrome to the Goodpasture antigen by the eluted antibodies and those from their respective sera further supported that the circulating and the kidney-bound anti-GBM antibodies have similar specificity. These observations extend the support to the clinical usage of plasmapheresis and more recently, immunoadsorption using staphylococcal protein A as the effective therapeutic measure for the removal of circulating anti-GBM antibodies in the management of Goodpasture's syndrome.
The incidence of common bile duct (CBD) pathology in a group of patients with benign biliary disease (n = 505) was found to be 23.2 per cent. The spectrum included 111 patients (90.2 per cent) with CBD stones, 37 of whom (33.3 per cent) had no symptoms or findings pre-operatively indicating CBD involvement. Five patients had papillary stenosis, three had postoperative CBD strictures, one had a choledochal cyst and one had an external biliary fistula. Of the 100 CBDs measuring more than 10 mm in diameter, 90 harboured calculi. In the remaining 23 CBDs measuring less than 10 mm, calculi were present in 21. The presence of CBD calculi was demonstrated by intra-operative cholangiography in 49 patients. In the remaining patients (n = 74), the diagnosis of CBD pathology was made either by percutaneous transhepatic cholangiography, endoscopic retrograde cholangio-pancreatography, T-tube cholangiography or peroperative palpation. The surgical procedures performed included choledochotomy and T-tube drainage (n = 74), transduodenal sphincteroplasty (n = 27) and choledochoduodenostomy (n = 18). The overall mortality and morbidity of CBD exploration was 3.3 per cent and 24.4 per cent respectively, which was significantly greater than that for cholecystectomy alone (0.3 per cent and 8.6 per cent respectively). Transduodenal sphincteroplasty carried a much higher mortality (11 per cent) and morbidity (52 per cent) when compared with other procedures.
Two tricyclic antidepressants, amitriptyline and imipramine, were evaluated for their in vitro cytogenetic effects in human lymphocyte cultures. Peripheral blood cultures from three normal healthy donors were set up for 72 hr for each of the drugs. The drugs were added at the start (72-hr exposure), 24 hr (48-hr exposure), and 48 hr (24-hr exposure) after initiation of the cultures. The concentrations evaluated at each exposure time were 50, 250, 1,000, and 10,000 ng/ml for amitriptyline and 25, 500, and 5,000 ng/ml for imipramine. The first two concentrations correspond to the plasma levels of the respective drugs after therapeutic doses. All treatments for a donor were given at the same time. Untreated cultures served as controls for the baseline frequency of the parameters assayed. The parameters assayed were chromosome aberrations, mitotic index, and sister chromatid exchanges (SCEs). Amitriptyline was found to be nongenotoxic at plasma levels by all the parameters assayed. However, frequencies of chromosome aberrations and SCEs were significantly increased at concentrations 4 and 40 times the plasma level (1,000 and 10,000 ng/ml) although the actual increases was small. The mitotic index was not affected at any concentration. Through imipramine showed a significant increase in chromosome damage at the upper plasma level and at concentrations higher than that, SCE frequency was significantly increased only at concentration higher than the plasma level (5,000 ng/ml), the actual increase being small for both these parameters. The mitotic index was not affected at any concentration. These results suggest that amitriptyline may be a slightly safer drug than imipramine from a genetic point of view.