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Biomedical subjects

R Chandra

Publications and source records attributed to R Chandra.

At least 145 records · Page 8Linked to original sources
PubMed1988

In vitro magnetic resonance properties of CNS neoplasms and associated cysts.

Fresh surgical specimens of central nervous system (CNS) neoplasms were analyzed with particular attention to differences between the T1 and T2 values of the solid and cystic components. Delineation of solid tumor from cyst is important, particularly when surgical intervention is planned, since only the solid portion need be excised. Total protein concentration determinations and microimmunoelectrophoresis for protein distribution and characterization also were performed on the fluid specimens. To diagnose a lesion on magnetic resonance based on T1 and T2 measurements, one must first have a catalog of values on which to base that diagnosis. The authors are reporting such values at 0.25 T. In addition, protein analysis of the fluid specimens has shown that the cysts of the CNS associated with CNS neoplasms are, in fact, transudates rather than collections of cerebrospinal fluid (CSF). Their T1 should permit differentiation from solid portions of neoplasms and from non-neoplastic syringohydromyelia.

Adolescent↗
PubMed1988

Cholesteryl ester storage disease: a patient with massive splenomegaly and splenic abscess.

Cholesteryl ester storage disease (CESD), a rare lysosomal storage disorder characterized by functional deficiency of acid lipase activity, classically features hepatomegaly in conjunction with lipid-laden macrophages containing excessive quantities of cholesteryl esters. We present a patient whose clinical course was complicated by massive, symptomatic splenomegaly, and an unsuspected splenic abscess. Computed tomographic and magnetic resonance imaging are correlated. Histologic, electron microscopic, and biochemical features are presented. To our knowledge, this is the first report of splenic abscess in CESD.

Abscess↗
PubMed1988

Effect of spermine on membranolytic effect of vitamin A in rats.

The effect of spermine on membranolytic effect of vitamin A has been studied on mitochondrial membrane integrity by examining phospholipase A2 activity and membrane phospholipids. Spermine arrest the vitamin A induced activity of mitochondrial phospholipase A2. The function of vitamin A in vision is fairly well understood. Though the part that vitamin A plays in vision is of high significance; vitamin A deficient animal not only become blind but eventually die. This indicates that vitamin A plays an indispensable role in general metabolism. The mechanism of absorption, transport and storage of vitamin A have been intensively studied [1, 8, 9]. Administration of vitamin A in large doses for prolonged periods is found to be toxic. This toxicity is termed as hypervitaminosis A. Excess of vitamin A to animals have been found to cause membrane labilization of various cellular organelles, e.g. mitochondria, lysosomes and release their contents. Alternations in membrane functions of liver mitochondria have also been observed in rats given excess of vitamin A. Polyamines have been shown to stabilize membrane structure against lysis or swelling for several microorganism and mammalian subcellular fractions [2, 4, 5, 7]. The stability of mitochondrial and lysosomal membranes are in reciprocal relationship with the activity of endogenous phospholipases bound to these membranes [4, 11]. Polyamines were shown to inhibit phospholipase A2 activity of heart mitochondria [12]. Phospholipase A2 detaches the fatty acid from the position of phosphatidyl choline, and the lysolecithin formed has a detergent effect that can produce membrane destabilization. The mechanism of inhibition by polyamines appears to be related to the effect of basic proteins as phospholipase digestion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Behavioral ratings and outcome of medical treatment for encopresis.

The relationship between behavior problems and encopresis remains controversial. Recent research suggests that children with encopresis do have numerous behavior problems, but that these problems are generally not as severe as the behavior problems found in children referred for mental health services. This study explores the relationship between baseline behavior ratings of encopretic boys, ages 6-11, on a standardized rating form, the Child Behavior Checklist (CBCL), and outcome of medical treatment for their encopresis. A strong correlation between the product of the sum of the factors on the internalizing scales and the sum of the factors on the externalizing scales and their interaction on the CBCL was associated with outcome. Specifically, moderate elevations of this function predicted good outcome at 3, 6, and 12 months. Very high elevations and minimal or no elevation predicted poor outcome at 3, 6, and 12 months. Possible reasons for these somewhat surprising results are discussed.

Child↗
PubMed1987

Membrane phospholipid organization in calcium-loaded human erythrocytes.

Intracellular Ca2+ levels in human erythrocytes were increased by incubating them with variable concentrations of Ca2+ in the presence of ionophore A23187. Experiments were done to confirm that the Ca2+ loading did induce changes in the cell shape and membrane protein composition. The effect of the increased cytoplasmic Ca2+ levels on the membrane phospholipid organization was analysed using bee venom and pancreatic phospholipases A2, Merocyanine 540 and fluorescamine as the external membrane probes. About 20% phosphatidylethanolamine (PE) and 0% phosphatidylserine (PS) were hydrolysed by the phospholipases in intact control cells, whereas in identical conditions these enzymes readily degraded, 20-30% PE and 7-30% PS, in Ca2+-loaded erythrocytes, depending on the cytoplasmic Ca2+ concentration. Also, Merocyanine 540 failed to stain the fresh or control erythrocytes, but it labeled the cells loaded with Ca2+. Furthermore, fluorescamine labeled approx. 20% PE in fresh or control erythrocytes while in identical conditions, significantly higher amounts of PE were modified in intact Ca2+-loaded cells. These results demonstrate that Ca2+ loading in human erythrocytes leads to loss of the transbilayer phospholipid asymmetry, and suggest that, together with spectrin, polypeptides 2.1 and 4.1 may also play an important role in maintaining the asymmetric distribution of various phospholipids across the erythrocyte membrane bilayer.

Bee Venoms↗
PubMed1987

Solid and papillary epithelial neoplasm of the pancreas. An ultrastructural and immunocytochemical study of six cases.

Solid and papillary epithelial neoplasms of the pancreas from six female patients were studied using immunohistochemistry and electron microscopy to define better their histogenesis. The tumors ranged in diameter from 5 to 15 cm (average: 9 cm), and, on cross section, most had areas of hemorrhage and necrosis, sometimes extensive. Microscopically, there was a solid and pseudopapillary pattern, with tumor cells typically having ovoid nuclei with delicate folding and indistinct nucleoli. Of note were the following: a relatively low mitotic rate (range: 0-6/20 hpf), the presence of hyaline globules (four of six cases), and collections of foam cells (three of six cases). Staining for cytoplasmic argyrophil granules was negative in each case. Ultrastructurally, the solid and papillary epithelial neoplasms of the pancreas showed evidence of acinar or ductular differentiation. Two contained zymogen granules, one had intermediate filaments (probably keratin), and three had abundant rough endoplasmic reticulum and mitochondria. Immunostaining was positive for chymotrypsin (six of six cases), trypsin (four of six), and amylase (three of six). None was positive for alpha-1-antitrypsin, neuron-specific enolase, pancreatic polypeptide, gastrin, glucagon, somatostatin, or insulin. The findings support an origin from exocrine pancreas, and follow-up indicates a low rate of malignancy, with local recurrence in two of the six patients.

Adolescent↗
PubMed1987

Circadian variations of the absolute eosinophil count and serum histaminase activity in tropical pulmonary eosinophilia.

Nine healthy volunteers and 25 tropical pulmonary eosinophilia (TPE) patients were used to study circadian variations of absolute eosinophil count (AEC) and serum histaminase activity (SHA). A marked circadian variation was found in AEC for healthy volunteers and TPE patients with the worst symptoms in the late evening and morning hours only; no rhythm could be detected in SHA for healthy subjects. However, TPE patients with worst symptoms in the late evening hours did exhibit a significant rhythm in SHA. Increased SHA in all TPE patients at all time-points of the 24 hour day-night cycle, irrespective of the worsening hours of symptoms in comparison to healthy controls, could be due to increased histamine production in such situations.

Amine Oxidase (Copper-Containing)↗
PubMed1986

Possible basis for membrane changes in nonparasitized erythrocytes of malaria-infected animals.

Previous studies (Gupta et al. (1982) Nature 299, 259-261) have shown that nonparasitized erythrocytes of Plasmodium knowlesi-infected monkeys contain the procoagulant phospholipid phosphatidylserine (PS) in the outer-half of their membrane bilayer. A reinvestigation of this problem has now revealed that in acute P. knowlesi infection, at least 30% of the infected animals do not have this abnormality. However, PS externalization was a consistent feature in the uninfected red cells of chronically infected animals. Also, a similar membrane change was observed in the red cells of uninfected splenectomized monkeys. These results strongly suggest that spleen plays an important role in maintaining the exclusive inner distribution of PS in the normal erythrocyte membrane, and that partial migration of this lipid to the outer monolayer in nonparasitized erythrocytes could be attributed to an abnormal physiology of this organ in malarial infection.

Animals↗
PubMed1986

Biochemical properties of the heme oxygenase inhibitor, Sn-protoporphyrin. Interactions with apomyoglobin and human serum albumin.

Sn-protoporphyrin is a strong competitive inhibitor of heme oxygenase and a potential pharmacological agent for the treatment of neonatal hyperbilirubinemia. Little is otherwise known about the biochemistry of tin porphyrins. We have investigated aspects of the chemistry of tin-protoporphyrin in aqueous solution and of its interactions with heme-binding proteins other than heme oxygenase, specifically apomyoglobin and human serum albumin. In the pH region 7-10, Soret region absorption studies of unbound Sn-protoporphyrin demonstrate a pH-dependent monomer-dimer equilibrium (KD congruent to 10(6) M-1 at pH 7) with little higher aggregation. Dissociation of the dimer is relatively slow at neutral pH, permitting interaction of protein ligands with monomeric and dimeric species to be distinguished and providing insights into kinetic mechanisms of porphyrin binding by heme-binding proteins. In the present study, the kinetics of interaction of Sn-protoporphyrin with apomyoglobin are presented as novel evidence that this binding proceeds by an induced fit mechanism. Binding of Sn-protoporphyrin to both apomyoglobin and serum albumin is unexpectedly weak. Between pH 7 and 9, the apparent affinity of Sn-protoporphyrin for apomyoglobin is less than 1/200 that of heme and, at pH 9, is also significantly less than that of protoporphyrin. The apparent affinity of Sn-protoporphyrin for human serum albumin is less than 1/1000 that of heme and 1/30 to 1/100 that of protoporphyrin. Competition studies between heme and Sn-protoporphyrin and between bilirubin and Sn-protoporphyrin indicate that Sn-protoporphyrin distributes differently among porphyrin-binding sites on serum albumin than does heme and that it is also not an effective competitor with bilirubin for bilirubin-binding sites. These results argue that Sn-protoporphyrin should not significantly alter normal mechanisms for the binding and transport of heme or of preformed bilirubin by serum albumin. From a more general perspective, the results indicate potentially unusual binding site selectivity by tin chelates; possible origins of this selectivity are discussed.

Apoproteins↗
PubMed1986

Segmental aganglionosis of the appendix.

Ignoring the pathologist's dictum that the appendix is not reliable for the identification of ganglion cells in suspected cases of total colonic aganglionosis, the author (K.D.A.) performed an ileostomy in a child whose appendix contained no ganglion cells. The ascending colon was later found to be ganglionic. The appendices from 36 cases of Hirschsprung's disease were examined and the number of ganglion cells in 10 high power fields was compared with 10 appendices from patients who did not have Hirschsprung's disease. There were no ganglion cells in any of the patients with total aganglionosis of the colon. Twenty-two patients with Hirschsprung's disease involving the sigmoid colon had an average of 3.0 ganglion cells per high power field (range 0.5 to 5.1). Five patients with longer segment aganglionosis had 2.2 cells per high power field (range 0 to 4.1). The index case fell into this group and was serially sectioned without finding any ganglion cells. The control group averaged 3.41 cells per high power field (range 1.4 to 5.9). There was no significant difference between the control group and the groups with less than total colonic aganglionosis. It is speculated that this case represents segmental Hirschsprung's disease with the skip area in the ascending colon.

Appendix↗
PubMed1986

Effects of mitotic activity and water content on the proton relaxation times in partially hepatectomized and sham-operated rat livers.

Proton relaxation times, T1 and T2, water content, and mitotic activity in control, sham-operated and partially hepatectomized rat livers were measured before surgery, and at 28 hours, 48 hours and six days after surgery. T1, water content, and mitotic activity increased after partial hepatectomy, but T1 was also elevated after sham operations, whereas neither water content nor mitotic activity changed. T2 was unaffected by either procedure. The T1 changed is more likely to be the result of surgery related stress than of changes in water content or growth rate.

Animals↗
PubMed1986

The effect of stress on proton relaxation times (T1 and T2) of rat liver.

T1 of the liver has been shown to lengthen after sham operation or partial hepatectomy, reaching a maximum about 24 hours after surgery. Surgical stress, which includes tissue injury and repair, has been suggested as the source of the change. We subjected rats to three types of stress that do not include tissue damage and repair to determine the role of stress alone in the length of T1 of the liver. Prolonged swimming, ACTH injection, or fasting did not affect T1 times. Tissue damage and/or repair appear to have a major role in determining T1 in the liver.

Adrenocorticotropic Hormone↗
PubMed1986

Prevalence of behavior problems and mental health utilization among encopretic children: implications for behavioral pediatrics.

The psychiatric literature traditionally has viewed encopretic children as having severe and characteristic behavior problems. Current psychiatric views as expressed in the Diagnostic and Statistical Manual of Mental Disorders, 3rd Edition (DSM-III), and in the pediatric literature, however, tend to regard the behavior problems of encopretic children as being rather mild or secondary to the consequences of the encopresis itself. Using a behavioral checklist with empirically derived factors (the Child Behavior Checklist), 55 children presenting for medical treatment of their encopresis have been assessed. Numerous behavior problems are reported on parental ratings, but the overall severity of behavior problems in this group of children falls below that found in children with behavior problems who are referred for mental health services. Most children presenting for medical management of encopresis have not been seen or evaluated by mental health services. Encopresis is a disorder in which psychological evaluation and intervention by the pediatrician may be advisable.

Adolescent↗
PubMed1986

Experimental pathogenesis of buffalo pox virus in rabbits: clinico-pathological studies.

Buffalo pox virus produced typical pock lesions on the skin of rabbits at the site of primary inoculation following an incubation period of 48-72 hr. Gross lesions in internal organs, characterized by focal or diffuse necrotic areas on lung, liver and spleen were seen from day 5 post-inoculation (p. i.). Isolated lesions of approximately 2 mm diameter appeared in skin, stomach, intestine and uterus from day 7 p. i. Histopathological changes, i. e. intra-alveolar and intra-bronchial haemorrhages were seen in lungs and severe fatty changes were found in the liver. Multinuclear cells were detected in liver during recovery. Virus particles were demonstrated by electron microscopy in skin, lung, liver and spleen lesions.

Animals↗