Biomedical subjects
Publications and source records attributed to R K Kumar.
A case of disseminated cryptococcosis with extensive ocular involvement is reported. The patient had pulmonary, meningeal, cerebral, cutaneous, lymph node, renal, adrenal and thyroid lesions, as well as granulomatous endophthalmitis.
A simple, easily readable system for permanent individual identification of rodents was accomplished by clipping off selected toes according to a code. Up to 10,000 animals could be consecutively numbered using this system.
Retrograde lymphatic permeation of the liver by a malignant neoplasm is an unusual phenomenon and has apparently not been reported with colonic carcinoma. This paper presents such a case: the features of the lesion are similar to those described for other primary sites.
Neonatal cerebral infarction or neonatal stroke is the second most common cause of neonatal seizures in term new born babies. It remains one of the least recognised entities in the neonatal text books and the awareness of its existence among general practitioners and practising paediatricians is very low. Cranial Ultrasound Scan (USS) is the standard imaging used by neonatologists and many neonatal intensive care units have their own scanners. However, USS may give a false sense of security especially in the term neonates and we report a case of neonatal cerebral infarction here and the need for computerised tomography (CT) for imaging.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
An improved method has been developed for separation of an enriched population of mouse type 2 pneumocytes, based on differential adherence and size fractionation of cells dissociated with trypsin. These cells were successfully maintained in primary culture in serum-free medium MCDB 201 supplemented with albumin, transferrin, and lipids. Whereas type 2 pneumocytes in serum-supplemented culture undergo phenotypic transformation into adherent flattened cells that resemble type 1 pneumocytes, this did not occur in serum-free culture. Both the morphology of the type 2 pneumocytes and their expression of surfactant protein A were maintained for at least 6 days in vitro. However, rapid loss of differentiated characteristics was induced by exposure of the cells to normal mouse serum. This was accompanied by a striking decrease in spontaneous DNA synthesis as assessed by incorporation of tritiated thymidine. When cultured in serum-free medium, the behavior of the type 2 pneumocytes on various extracellular matrix components was different from that reported for serum-supplemented culture. Serum-free culture of type 2 pneumocytes may offer significant advantages for evaluation of the secretory activities of these cells in vitro.
The secretion of molecular species related to epidermal growth factor (EGF) by pulmonary alveolar and parenchymal macrophages was investigated in an experimental model of pulmonary fibrosis in mice. Macrophages were isolated from cells obtained by bronchoalveolar lavage or by enzymatic disaggregation of lung tissue at intervals following induction of pulmonary injury by intratracheal injection of bleomycin. Production of EGF receptor-binding activity by these cells and concentrations of this activity in bronchoalveolar lavage fluid were measured using a radioreceptor assay. Following short-term culture under serum-free conditions, there was significantly increased production of EGF receptor-binding activity by parenchymal macrophages, which was demonstrable at 1 and 2 weeks after administration of bleomycin to susceptible C57BL/6 mice. The activity exhibited affinity for heparin and was completely blocked by an antibody to EGF. There was no such increase in production of receptor-binding activity by alveolar macrophages or in the concentration of activity in lavage fluids. Nor was there any significant increase in production of EGF receptor-binding activity by parenchymal macrophages from bleomycin-resistant BALB/c mice. These results imply that selective activation of interstitial macrophages to secrete an EGF-like growth factor may contribute to the development of pulmonary fibrosis.
Numerous investigators have described maintenance of airway epithelial cells from various species in a differentiated state in primary culture. Because the number of cells that can be isolated from the mouse trachea is very small, published techniques are unsuitable for this species. To examine the production of growth factors by murine airway epithelial cells, the authors developed a method for culture of mouse tracheal epithelial cells from explants, in which the population of cells was expanded in the presence of epidermal growth factor and insulin-like growth factor-I, which exhibited synergistic mitogenic activity. After subculture, an essentially pure population of epithelial cells was recovered, with a yield approximately tenfold greater than reported using protease dissociation of cells from the trachea. Culture of the cells at passage 2 on a collagen gel substratum induced differentiation toward a synthetic/secretory phenotype, accompanied by marked diminution in spontaneous and mitogen-induced DNA synthesis without loss of viability. In parallel, secretion of immunoreactive transforming growth factor-beta by the epithelial cells was strikingly increased, but could be partially down-regulated in the presence of mitogenic growth factors.
BACKGROUND: The neonatal age group is considered to be one of the important risk factors for perioperative morbidity and mortality as well as poor long-term patency following Blalock-Taussig shunts. METHODS AND RESULTS: Out of a total of 190 patients who underwent Blalock-Taussig shunts in our institute between July 1998 and July 2000, 20 patients were aged less than 30 days and this neonatal cohort was studied retrospectively. The mean age was 18+/-11 days (range: 3-30 days). The mean weight of the babies was 3.1+/-0.7 kg, the smallest weighed 2.1 kg. The cardiac anatomy was tetralogy of Fallot with pulmonary atresia in 6, pulmonary atresia with intact ventricular septum in 3, tricuspid atresia in 5 and complex single ventricle physiology in the rest. All patients were deeply cyanotic and preoperative prostaglandin E1 was needed in 10 patients to ensure ductal patency and maintain oxygen saturations prior to the shunt operation. The mean hilar right and left pulmonary artery sizes were 3.99+/-0.44 mm and 3.69+/-0.79 mm, respectively. Three patients (15%) had significant stenosis at the site of duct insertion. The shunts were accomplished with 3.5 mm polytetrafluoroethylene grafts in 7 patients (35%) and 4 mm in the rest. The mean duration of mechanical ventilation was 2.0+/-2.83 days, one patient who developed bronchopneumonia needed prolonged ventilation for 14 days. The mean intensive care unit stay was 4.79+/-2.66 days. The mean hospital stay was 11.7+/-6.4 days. Five patients who developed sepsis stayed beyond 14 days. There were 3 deaths (immediate post-operative shock and possibly shunt malfunction in 1, bronchopneumonia in 1 and late shunt thrombosis at 3 months in 1). Two patients had late shunt block, one of those mentioned above and the other at 3 months secondary to infective endarteritis of the right pulmonary artery. All these infants received 4 mm grafts. All the 3.5 mm grafts were patent at follow-up. Seventeen patients were alive and well at follow-up (mean: 9 months, range: 3-21 months) with a mean resting systemic oxygen saturation of 77% (66%-95%). CONCLUSIONS: The overall shunt patency rate after neonatal Blalock-Taussig shunt is about 80% on intermediate term follow-up. A smaller graft size (3.5 mm) does not appear to be an incremental risk factor for shunt blockade and operative mortality.
BACKGROUND: Modified Blalock-Taussig shunts are used to palliate a variety of cyanotic heart diseases associated with reduced pulmonary blood flow. Acute shunt thrombosis in patients with shunt-dependent pulmonary blood flow can result in life-threatening hypoxia. We describe our experience of emergency transcatheter recanalization in 5 severely hypoxic children with acute shunt occlusion. METHODS AND RESULTS: Five patients with ages ranging between 5 and 24 months (median 11 months) and weight ranging from 4 to 8 kg (median 5 kg) presented with severe hypoxia, acidosis and hypotension following acute occlusion of modified Blalock-Taussig shunts placed 11 days to 12 months ago. As severe hypoxia (saturation range 3 5%-5 0%), acidosis and a state of shock in all the patients increased the risk for a redo surgical procedure, they were taken up for emergency transcatheter recanalization within 2-6 hours of hospitalization. This was done by positioning a Judkin's right coronary catheter at the mouth of the thrombosed shunt, crossing the shunt with a guidewire and serial dilatations with coronary and/or peripheral angioplasty balloons to the size of the graft. This technique was immediately successful in 4 of the 5 patients, thereby avoiding a repeat palliative operation. In 2 patients with residual stenosis, stents were used to restore luminal patency. One patient with acute stent thrombosis was managed successfully with local delivery of thrombolysis for 36 hours, which resulted in good luminal patency. At follow-up after 6 and 12 months, the shunts in both the stented patients are patent, with an oxygen saturation of 78% and 80%, respectively. In 2 other patients who had undergone plain balloon angioplasty, the shunts remained patent for 11 days (died of bronchopneumonia and septicemia) and 3 months, respectively. The procedure was unsuccessful in one very sick patient in whom the shunt had a tortuous course. CONCLUSIONS: Transcatheter recanalization of an acutely thrombosed Blalock-Taussig shunt is feasible. It can offer satisfactory short-term palliation in selected patients. Stents may play a role in patients with residual narrowing after dilatation. The procedure can be expeditiously accomplished in an emergency situation in a severely hypoxic child and may be a realistic alternative to surgery or thrombolysis.
Measurement of the quantity of 125I-labelled Concanavalin A bound by disaggregated cells from a series of 20 primary murine mammary carcinomas has shown that there is no relationship between the binding of this lectin and capability of the cells to colonise the lungs after intravenous injection. However, cells taken from pulmonary deposits formed by those tumors able to colonise the lungs consistently bound greater amounts of the radio-labelled lectin than cells from the corresponding primary tumour (paired t-test, p less than 0.05). Also cells obtained from tumours formed by transplantation of pulmonary deposits into the mammary fat pad bound still more of this lectin than cells from either corresponding pulmonary deposits or primary tumours. The findings indicate that the higher lectin binding characterising cells from metastatic deposits is not site-induced and may reflect either a selective advantage of cells with these properties for metastasis formation or phenotypic changes in the cells during the metastatic process.
BACKGROUND: The clinical importance of coronary collaterals in the presence of obstructive coronary artery disease is not clearly defined. METHODS: We retrospectively analysed the clinical and angiographic features of 100 patients with > or = 90% luminal diameter stenosis involving at least one major coronary artery. Coronary collaterals were graded 0 to 4 (Nitzberg's classification) and studied to determine their influence on clinical parameters. RESULTS: Thirty patients had no collaterals (group I) and 70 showed collaterals (group II). There were no significant differences between groups I and II in age and sex distribution, prevalence of risk factors of coronary artery disease (hypertension, diabetes, smoking, hypercholesterolaemia), duration of symptoms of coronary artery disease and prior myocardial infarction. Groups I and II had similar types (left anterior descending 73% v. 71%; left circumflex 50% v. 50% and right coronary 37% v. 56%) and numbers of arteries involved (one 47% v. 41%; two 47% v. 40%; three 7% v. 19%). Group II had a significantly lower prevalence of rest angina (14% v. 47%, p = 0.002). This difference was also evident when the patients were re-classified according to the extent of flow through the collaterals. Those with good collateralization (Nitzberg grades 3 and 4) had a lower prevalence of rest angina (13%) compared to those with poor collateralization (Nitzberg grades 0 to 2; 35%, p = 0.02). CONCLUSION: Coronary artery collaterals may reduce the incidence of rest angina in patients with obstructive coronary artery disease.
Explore the source record for details and available documents.
Little information is available on the use of thromobolytic therapy in infants for femoral artery thrombosis after cardiac catheterisation. We report 12 cases (mean age: 4 months; range: 1-9 months) who received intravenous streptokinase (3000 U/kg bolus, 1000 U/kg/h) infusion. Five of them had undergone transarterial balloon dilatation procedures. Streptokinase was administered 48 h after catheterisation and continued for 4-20 h (mean 11.5 h). No detailed haematologic monitoring was done during therapy. Distal pulses were restored in all the patients. No complications were seen except a minor local ooze in two patients. We found that intravenous streptokinase is a safe and effective therapy for femoral artery thrombosis following cardiac catheterisation in infants.