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Biomedical subjects

R S Chana

Publications and source records attributed to R S Chana.

At least 19 recordsLinked to original sources
PubMed2004

Cytodiagnosis of yolk sac tumor.

To analyze cytomorphologic features of yolk sac tumors of childhood. Four cases of pediatric yolk sac tumor (YST), diagnosed by fine needle aspiration cytology were reviewed (1998-2002). Age of patients ranged from 1(1/2) to 5 years. Three cases presented clinically with an intra-abdominal mass while one case presented with a testicular mass. Fine needle aspirates had been obtained directly as well as under radiologic (USG/CT) guidance. Smears were stained with H & E and Papanicolaou stain. In all cases values of serum alpha-fetoprotein and hCG were available preoperatively. Histopathologic diagnosis was correlated with cytologic findings in all the cases. Cytologic examination showed richly cellular smears with a combination of morphological patterns. Characteristically, tumor cells were arranged in papillary groups, tight cell clusters and formed acinar structures. Cells showed enlarged, moderately pleomorphic, hyperchromatic nuclei and moderate amount of cytoplasm, some of which displayed cytoplasmic vacuolation, displacing the nuclei eccentrically. Preoperatively, serum alpha-fetoprotein level was raised in all cases. Histopathology confirmed the cytologic diagnosis. Yolk sac tumor is common among the germ cell tumors of pediatric age group which presents a spectrum of cytomorphologic features having important differences with other germ cell neoplasm, e.g. embryonal carcinoma. Clinicoradiologic features and tumor markers are additionally helpful for an accurate cytologic diagnosis.

Abdominal Neoplasms↗
PubMed2001

Serum cortisol and prolactin response to surgical stress in infants and children.

In a prospective study on 40 infants and children undergoing elective surgery under general anaesthesia, serum cortisol and prolactin levels were compared to assess hormonal response to stress as regards to age, sex, length of surgery and anaesthetic techniques. The rise in serum cortisol was independent of age, sex, length of surgery and anaesthetic techniques while percentage rise in serum prolactin were more in females compared to males and significant post-induction surge irrespective of sex.

Analysis of Variance↗
PubMed2000

Low-density lipoprotein stimulates mesangial cell proteoglycan and hyaluronan synthesis.

BACKGROUND: Hyperlipidaemia leads to glomerulosclerosis in small mammals and may contribute to progressive renal disease in man. One prominent feature of lipid-induced glomerular injury in animal models is the accumulation of mesangial matrix. These studies were designed to investigate whether low-density lipoprotein (LDL) enhanced mesangial cell (MC) matrix deposition by modulating the production of proteoglycans (PG) and hyaluronan (HA). METHODS: Growth arrested human MC were metabolically labelled with either 50 microCi/ml Na(2)[(35)S]sulphate or 25 microCi/ml [(3)H]glucosamine and stimulated with LDL (10-100 microg/ml). The radiolabelled PG and HA extracted from the cell layer and the culture medium were isolated, quantified and characterized. Comparison of the PG core proteins synthesized by MC was carried out using Western blot analysis. RESULTS: LDL stimulation led to a dose- and time-dependent increase in [(35)S]sulphate incorporation into PG in the culture medium and to a lesser extent in the cell layer. Analysis of the glycosaminoglycan (GAG) chains showed no difference in either their size or charge. Enzyme digestion studies demonstrated that the synthesis of both chondroitin sulphate PG (CSPG) and heparan sulphate PG (HSPG) was enhanced as was the production of the core proteins of versican (a large CSPG), perlecan (a basement membrane HSPG) and to a lesser extent decorin (a small dermatan sulphate PG (DSPG)). An increase in HA synthesis was also demonstrated in [(3)H]glucosamine labelled cells following LDL stimulation. CONCLUSION: LDL selectively enhances the synthesis of specific PG and HA by mesangial cells. Such effects may contribute to the expansion of the mesangial matrix and modify cell-matrix interactions in lipid-induced renal damage.

Blotting, Western↗
PubMed1999

Fibronectin augments monocyte adhesion to low-density lipoprotein-stimulated mesangial cells.

BACKGROUND: Glomerular monocyte infiltration is an early feature of lipid-mediated renal injury in animal models. Interactions between mesangial and infiltrating mononuclear cells may contribute to the development of glomerular scarring. METHODS: Adherence of U-937 monocytes to low-density lipoprotein (LDL)- or tumor necrosis factor alpha (TNFalpha)-prestimulated human mesangial cells was assessed by colorimetry of nuclear staining with crystal violet. Blocking antibodies were added to examine the mechanisms of binding. Adhesion molecule expression and fibronectin synthesis were measured by ELISA. RESULTS: Preincubation of mesangial cells for 24 hours with LDL (100 micrograms/ml) or mildly oxidized (minimally modified) LDL (MM-LDL) increased monocyte adhesion by 207% and 240%, respectively, compared with control nonstimulated cells (100%). TNFalpha (100 U/ml) enhanced binding by 335% and up-regulated intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression by 505% and 179%, respectively, as compared with MM-LDL (120% and 116%) and LDL, which had no effect. Blocking antibodies to these adhesion molecules inhibited monocyte binding to TNFalpha- and, to a lesser extent, MM-LDL-primed mesangial cells, but had no effect after LDL pretreatment. In contrast to TNFalpha, MM-LDL and LDL increased mesangial cell-associated fibronectin, whereas antibodies to fibronectin inhibited monocyte binding to lipoprotein-stimulated but not TNFalpha-stimulated cells. CONCLUSIONS: Although enhanced monocyte adhesion to TNFalpha- and, to a lesser extent, MM-LDL-stimulated mesangial cells is mediated by changes in ICAM-1 and VCAM-1 expression, both LDL and MM-LDL promote similar cellular interactions as a result of increased fibronectin production.

Cell Adhesion↗
PubMed1994

Oxidation of low density lipoprotein by mesangial cells may promote glomerular injury.

Low density lipoprotein (LDL) deposition and local oxidation play a key role in the pathogenesis of atherosclerosis and may likewise contribute to glomerular injury. These studies were designed to determine whether cultured human mesangial cells oxidize homologous LDL and to compare the effects of unmodified and oxidized lipoprotein on cell proliferation, viability and eicosanoid production. Cell-mediated lipoprotein oxidation was demonstrated and could be suppressed by oxygen free radical scavengers and inhibitors of arachidonic acid metabolism. When incubated with cells, oxidized LDL (Ox-LDL) at concentrations up to and including 100 micrograms/ml reduced 3H-thymidine incorporation without causing cytotoxicity as assessed by lactate dehydrogenase release. Under the same conditions there was a concentration-dependent increase in the synthesis of prostaglandins E2,6-keto-PGF1 alpha and thromboxane B2. In contrast, unmodified LDL enhanced DNA synthesis at concentrations less than 40 micrograms/ml and had little effect on eicosanoid production. These results demonstrate that exogenous oxidized LDL inhibits mesangial cell proliferation and increases eicosanoid synthesis. Unmodified lipoprotein can be directly oxidized by these cells through mechanisms that involve generation of oxygen free radicals.

Cell Division↗
PubMed1993

Interactions between lipoproteins, glomerular cells and matrix.

Lipid deposition, mononuclear cell infiltration and accumulation of mesangial matrix components are recognized as early events in the development of glomerulosclerosis whilst correction of plasma lipid abnormalities slows the progression of renal disease in experimental models. In vitro studies have demonstrated that low density lipoprotein (LDL) is bound and internalized by mesangial cells, acts synergistically with growth factors to stimulate cellular proliferation and modifies secretion of chemotactic mediators and matrix components. LDL incubated with mesangial cells becomes oxidized and in this modified from inhibits cell proliferation and causes cytotoxic injury. Oxidation of LDL also modulates its effects on cell secretory function. Since proteoglycans secreted by mesangial cells bind LDL particles, excess matrix accumulation may exacerbate lipoprotein-mediated injury. These findings suggest that lipoproteins deposited and oxidized in the glomerulus may promote inflammation, cell injury and sclerosis.

Animals↗
PubMed1993

A prospective study of closure techniques of abdominal incisions in infants and children.

In a prospective study of layered versus mass closure of abdominal incisions in infants and children, 34 cases underwent wound closure by layered and mass closure technique on an alternate basis. All the patients were assessed for their nutritional status and haemoglobin level pre-operatively, and wound complications were compared with respect to closure technique, nutritional status and normal haemoglobin level. Presence of protein energy malnutrition and anaemia did not increase the risk of wound complications with either of the technique.

Abdomen↗
PubMed1991

Peri-anesthetic management of tracheo-esophageal fistula.

During a 3-year period 11 neonates underwent general anesthesia for primary repair of tracheo-esophageal fistula (TEF). The age ranged from 1-10 days. Out of these patients, 8 (72.7%) had atresia of the esophagus with a blind upper pouch and lower segment communicating with a trachea. A total of 7 patients (63.6%) had aspiration pneumonitis pre-operatively. Intubation was difficult in 3 (27.3%). There was no intraoperative mortality. However, the incidence of post-operative mortality was 27.3% (3 cases). The cause of death in all these cases was severe non-resolving pneumonia.

Anesthesia, General↗
PubMed1990

Structure and motion of phospholipids in human plasma lipoproteins. A 31P NMR study.

The structure and motion of phospholipids in human plasma lipoproteins have been studied by using 31P NMR. Lateral diffusion coefficients, DT, obtained from the viscosity dependence of the 31P NMR line widths, were obtained for very low density lipoprotein (VLDL), low-density lipoprotein (LDL), high-density lipoproteins (HDL2, HDL3), and egg PC/TO microemulsions at 25 degrees C, for VLDL at 40 degrees C, and for LDL at 45 degrees C. At 25 degrees C, the rate of lateral diffusion in LDL (DT = 1.4 x 10(-9) cm2/s) is an order of magnitude slower than in the HDLs (DT = 2 x 10(-8) cm2/s). At 45 degrees C, DT for LDL increases to 1.1 x 10(-8) cm2/s. In contrast, DT for VLDL increases only slightly going from 25 to 40 degrees C. The large increase in diffusion rate observed in LDL occurs over the same temperature range as the smectic to disordered phase transition of the core cholesteryl esters, and provides evidence for direct interactions between the monolayer and core. In order to prove the orientation and/or order of the phospholipid head-group, estimates of the residual chemical shift anistropy, delta sigma, have been obtained for all the lipoproteins and the microemulsions from the viscosity and field dependence of the 31P NMR line widths. For VLDL and LDL, the anisotropy is 47-50 ppm at 25 degrees C, in agreement with data from phospholipid bilayers. For the HDLs, however, significantly larger values of 69-75 ppm (HDL2) and greater than 120 ppm (HDL3) were obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Diffusion↗
PubMed1990

Dynamic structure of the lower density lipoproteins. I. Incorporation of high levels of labelled lipids into very low and low density lipoproteins.

Selectively labelled lipids have been incorporated into the surface monolayer of human serum low density lipoprotein (LDL) and very low density lipoprotein (VLDL). From 3 to 17 mol% of phosphatidylcholine, selectively deuterated at various positions along the sn-2-acyl chain, was transferred from unilamellar vesicles to VLDL using a partially purified phosphatidylcholine transfer protein. Selectively deuterated palmitic acids were incorporated into LDL (6-20 mol%) and into VLDL (7-10 mol%). Electron microscopy, light scattering, and 31P nuclear magnetic resonance indicated that particle size remained unchanged. Gel exclusion chromatography and chemical analysis showed no difference in hydrodynamic properties and only slight alteration to particle component ratios. Biological activity of labelled VLDL was measured from the rate of cholesterol esterification by cultured J774A.1 cells. Effect of labelling LDL was evaluated by monitoring LDL uptake and degradation by cultured human skin fibroblasts. In all cases the lipoproteins containing labels were indistinguishable from their native counterparts.

Animals↗
PubMed1990

Dynamic structure of the lower density lipoproteins. II. Deuterium NMR studies of the monolayer of very low and low density lipoproteins.

The order of phosphatidylcholine (PC) acyl chains in the surface monolayer of very low density lipoproteins (VLDL) and low density lipoproteins (LDL) has been determined from 2H nuclear magnetic resonance order parameters, SCD, using selectively deuterated PC or palmitic acids. From the computer simulated line shapes, we find two distinct phospholipid domains within the amphiphilic monolayer of both VLDL and LDL. In the more ordered domain of LDL, SCD was approximately 0.3 for the "plateau" chain region. The SCD values of VLDL particles are similar to those of LDL for the 5,6- and 11,12-positions, hence we suggest the organization of the more ordered region of VLDL and LDL are similar. The domain of low order in LDL comprises less than 10% of the phospholipid molecules (we do not distinguish between PC and sphingomyelin), having approximately the same order (SCD less than 0.1) as egg PC - sphingomyelin unilamellar vesicles. In VLDL, the domain of low order comprises between approximately 10 and approximately 20% of the phospholipid molecules and the entire acyl chain is in an essentially isotropic environment (SCD less than 0.02). We prepared VLDL-sized microemulsions composed of egg PC, deuterated PC, and triolein to test whether the apoproteins were responsible for creating the two differently organized domains in VLDL and LDL. Surprisingly, these protein-free particles also showed two domains of different order at two temperatures. The high order region, however, is less ordered than in VLDL and LDL. We explain two surface domains of PC in terms of lipid organization and the unique interactions of lipids in the various lipoprotein particles.

Chemical Phenomena↗
PubMed1989

Gastroesophageal reflux in infants and children.

Seventy-five infants and children presenting during the period December 1984 to December, 1987 with the clinical features of vomiting, failure to thrive, chronic cough, recurrent pneumonia and atypical asthma were evaluated for gastroesophageal reflux by standard barium esophagram. Fifty six cases (74.7%) and as many as 80% of the infants studied had gastroesophageal reflux; Grade II reflux was seen in 12 cases, Grade III in 30 and Grade IV in 14 cases. The patients with gastroesophageal reflux were put on medical treatment. All the patients had subjective improvement after 6 weeks to 6 months of conservative treatment and none of them developed further complications of gastroesophageal reflux during a follow-up period varying from two months to fifteen months. Anti-reflux surgery was not considered owing to the subjective improvement in all the patients on conservative treatment. We conclude that gastroesophageal reflux is very common in infants and children and urge the need to evaluate the patients presenting with the symptoms suggesting gastroesophageal reflux by barium esophagram; conservative treatment is the mainstay in the management of these children.

Barium↗
PubMed1988

Lipid-lipid interactions in reconstituted high-density lipoproteins by deuterium nuclear magnetic resonance.

Lipid-lipid interactions between the core and monolayer have been studied by using reconstituted high-density lipoproteins (rHDLs) composed of apoHDL3 with either dipalmitoylphosphatidylcholine (DPPC) or egg phosphatidylcholine (egg PC) as the monolayer and either cholesteryl oleate (CO) or triolein (TO) as the core. The effect of the monolayer on the core was observed by deuterium nuclear magnetic resonance (2H NMR) studies of rHDLs containing the core component cholesteryl [18, 18, 18-2H3] oleate [( 2H3]CO) or tri[16,16-2H2]oleoylglycerol [( 2H6]TO) surrounded by a monolayer of either DPPC or egg PC as a function of temperature. The reverse effect, that of the core on the monolayer, was examined by both 2H and 31P NMR studies of rHDLs containing [5,5-2H2]PC in the presence of CO or TO as a function of temperature. The 2H NMR line widths of [2H3]CO and [2H6]TO were considerably broader and showed a greater temperature dependence in rHDLs containing DPPC than in those containing egg PC. Similarly, the C-2H order parameters of [2H2]PC were higher and showed a greater temperature dependence in rHDLs containing CO than in those containing TO. In contrast, the 31P NMR line widths were identical for both [2H2]-PC/CO/apoHDL3 and [2H2]PC/TO/apoHDL3 at 25 and 6 degrees C, showing only a slight temperature dependence. Thus, acyl chains of both the monolayer and core components show increased order when in contact with neighboring lipids of higher order. The data demonstrate a direct effect of core cholesteryl esters and triglycerides with the phospholipid monolayer of HDL.

Deuterium↗
PubMed1987

Surface diffusion in human serum lipoproteins.

From the viscosity dependence of the 31P NMR signals, the diffusion coefficients DT of phospholipid molecules in the surface monolayer of HDL, LDL and VLDL have been determined. DT for HDL3 and HDL2 are found to be 2.3 X 10(-8) cm2/s and 1.8 X 10(-8) cm2/s, respectively. These values are similar to values reported for diffusion of phospholipid molecules in phospholipid bilayers above the gel to liquid crystalline phase transition temperature. Viscosity dependence of [16,16,16-2H3]phosphatidylcholine incorporated into HDL2 yielded a value similar to that determined by 31P (DT = 1.9 X 10(-8) cm2/s). Slower diffusion coefficients were measured for LDL2 and VLDL. VLDL had a value DT = 9.1 X 10(-9) cm2/s. The diffusion coefficient for LDL2 was 1.4 X 10(-9) cm2/s. Thus, diffusion of phospholipids in LDL2 is a full order of magnitude slower at 25 degrees C than diffusion of phospholipids in the HDLs.

Diffusion↗
PubMed1985

Covered exstrophy and visceral sequestration: a rare exstrophic variant.

We report a case of covered exstrophy and sequestration of a segment of bowel on the surface of the abdomen, which is a rare variant of the exstrophic complex. The external genitalia and urinary continence were normal. Simple excision of the ectopic bowel was curative.

Abnormalities, Multiple↗