Search PubMed⌕ Search

Biomedical subjects

A Chattopadhyay

Publications and source records attributed to A Chattopadhyay.

At least 19 recordsLinked to original sources
PubMed2003

Polyglandular autoimmune syndrome type 1 without chronic mucocutaneous candidiasis in a 16 year-old male.

A 16 year-old boy presented with adrenal crisis and was incidentally found to have features of latent tetany. Also detected were Hashimoto's thyroiditis, alopecia and subnormal T cell function, and he was diagnosed as having polyglandular autoimmune syndrome type 1 (PGA-1), although chronic mucocutaneous candidiasis, a hallmark of PGA-1, was absent. The presentation of several components of this disorder at one time and at this age is uncommon, and the features of overt hypoparathyroidism were probably masked by associated adrenal insufficiency.

Adolescent↗
PubMed2002

Autosomal recessive inheritance of RYR1 mutations in a congenital myopathy with cores.

Central core disease (CCD) is a congenital myopathy due to dominant mutations in the skeletal muscle ryanodine receptor gene (RYR1). The authors report three patients from two consanguineous families with symptoms of a congenital myopathy, cores on muscle biopsy, and confirmed linkage to the RYR1 locus. Molecular genetic studies in one family identified a V4849I homozygous missense mutation in the RYR1 gene. This report suggests a congenital myopathy associated with recessive RYR1 mutations.

Biopsy↗
PubMed2002

Duodenojejunal obstruction by a hemangioma.

Gastrointestinal obstruction by hemangiomas is exceedingly rare. We report a case of a duodenojejunal obstruction caused by a large hemangioma. The patient underwent a gastrojejunostomy for relief of the obstruction and has been symptom-free, although the hemangioma persists.

Child, Preschool↗
PubMed2002

Unilateral inguinal ectopic scrotum with covered exstrophy.

A case of ectopic scrotum located in the right inguinal area and associated with covered exstrophy and ipsilateral renal agenesis is described. Initially, repair of the exstrophy was performed. Scrotal reconstruction was carried out after 1 year, during which time the patient developed an inguinal hernia in the ectopic scrotum. The literature is reviewed and the scrotal reconstruction procedure is discussed.

Choristoma↗
PubMed2002

Soave procedure for infants with Hirschsprung's disease.

OBJECTIVE: Traditionally the surgical treatment of Hirschsprung's disease (H.D.) includes preliminary colostomy in normally innervated bowel followed by one of several pull through procedures. The transanal single stage Soave procedure eliminated the need for preliminary colostomy and intraabdominal dissection. It is a recent concept in the management of this disease, and this is the first experience to be reported from India. METHODS: Four children aged 3 weeks to one year underwent transanal pull through procedure over a two month period. A rectal mucosectomy was performed starting 0.5 cm. proximal to the dentate line and extending proximally to the level of intraperitoneal rectum. The muscular sleeve was divided circumferentially to allow the full thickness mobilization of the proximal colon. Ganglion cells were confirmed by frozen section and bowel was transected. The rectal muscular cuff was divided longitudinally and the anastomosis was completed. RESULTS: Operative time including the frozen section averaged 160 minutes and average length of the bowel resected was 22 cm. There were no postoperative complications and all patients were discharged on seventh postoperative day. Median follow-up was 5 months (4-6 months) and stool output ranged from 2-4 per day. CONCLUSION: The authors conclude that a single stage transanal Soave's pull through for Hirschsprung's Disease can be performed successfully in infants. When compared to conventional pull through procedure, it has the potential advantage of lower cost, less risk of damage to pelvic structures, absence of any abdominal incision, a lower incidence of intraperitoneal bleeding and adhesion formation. The preliminary functional results suggest that the patients gain early bowel function post operatively without soiling or constipation.

Anastomosis, Surgical↗
PubMed2002

Pyriform sinus fistula.

Pyriform sinus fistulae/sinuses are rare causes of recurrent cervical abscess, especially on the left side. They can also present as acute thyroiditis. Treatment in the form of simple incision and drainage is invariably unsuccessful, and the entity may be confused with the residual tract of a second branchial arch anomaly. We report a case of pyriform sinus fistula, and believe that this is only the second case report in India. We feel that greater awareness can lead to proper and appropriate diagnosis of this anomaly.

Abscess↗
PubMed2002

Chromobacterium violaceum infection: A rare but frequently fatal disease.

The authors report a rare case of Chromobacterium violaceum infection in a 2-month-old child. She presented with an apparently localized abscess, which appeared to respond well to therapy. However, the infection recurred later with a fulminant course. The organism frequently is dismissed as a contaminant or not identified properly, and the fatality rates are high. A high degree of awareness about this infection needs to be created, especially among pediatricians and pediatric surgeons, because children appear to be infected more commonly than adults, and aggressive therapy is needed to save these patients.

Abscess↗
PubMed2002

Spinal muscular atrophy with progressive myoclonic epilepsy: report of new cases and review of the literature.

Spinal muscular atrophy (SMA) is a clinically and genetically heterogeneous disease characterised by loss of motor function and muscle atrophy due to anterior horn cell degeneration. The most common variant is chromosome 5-linked proximal SMA, ranging in severity from congenital onset and infantile death to onset in adult life. Genetically separate variants with different distribution of weakness and/or additional features such as central nervous system involvement have been described. A rare variant with associated myoclonic epilepsy and lower motor neuron disease had been previously described in three families before the SMN gene, responsible for the common form of SMA, was isolated. We report four patients from two additional families affected by a syndrome characterised by severe and progressive myoclonic epilepsy and proximal weakness, tremor and lower motor neuron disease proven by electrophysiologic and muscle biopsy findings. Extensive metabolic investigations were normal and genetic analysis excluded the SMN gene. This study confirms that the association of myoclonic epilepsy and motor neuron disease represents a separate clinical and genetic entity from chromosome 5-linked SMA, the primary defect of which remains unknown.

Biopsy↗
PubMed2001

Transition temperature of ferromagnetic semiconductors: a dynamical mean field study.

We formulate a theory of doped magnetic semiconductors such as Ga(1-x)Mn(x)As which have attracted recent attention for their possible use in spintronic applications. We solve the theory in the dynamical mean field approximation to find the magnetic transition temperature T(c) as a function of magnetic coupling strength J, carrier density n, and Mn density x. We find that T(c) is determined by a subtle interplay between carrier density and magnetic coupling.

Journal Article↗
PubMed2001

Evidence that phospholipase C from the sperm is not responsible for initiating Ca(2+) release at fertilization in mouse eggs.

Release of Ca(2+) from intracellular stores at fertilization of mammalian eggs is mediated by inositol 1,4,5-trisphosphate (IP3), but the mechanism by which the sperm initiates IP3 production is not yet understood. We tested the hypothesis that phospholipase C (PLC) activity introduced into the mouse egg as a consequence of sperm-egg fusion is responsible for causing Ca(2+) release. We demonstrated that microinjecting purified, recombinant PLCgamma1 protein into mouse eggs caused Ca(2+) oscillations like those seen at fertilization. However, the PLC activity in the minimum amount of purified PLCgamma1 protein needed to elicit Ca(2+) release when injected into eggs was approximately 500-900 times the PLC activity contained in a single sperm. This indicates that a single mouse sperm does not contain enough PLC activity to be responsible for causing Ca(2+) release at fertilization. We also examined whether phosphatidylinositol 3-kinase (PI3K) could have a role in this process, and found that several inhibitors of PI3K-mediated signaling had no effect on Ca(2+) release at fertilization.

Animals↗
PubMed2001

BAD/BCL-[X(L)] heterodimerization leads to bypass of G0/G1 arrest.

The pro-apoptotic molecule BAD binds BCL-[X(L)] or BCL2 and inactivates their survival function. In addition to their anti-apoptotic function, BCL2 and BCL-[X(L)] also delay cell cycle entry from quiescence. We found that the BH3-only molecule BAD also exerted a cell cycle effect. BAD expression resulted in failure to cell cycle block in growth arrest conditions. In low serum and in confluence, fibroblasts constitutively or inducibly expressing BAD persisted in S phase, continued to incorporate BrdU, and exhibited sustained cyclin E/cdk2 activity. Mutation analysis indicated that the cell cycle effect of BAD was not dependent on its phosphorylation status or subcellular localization, but strictly co-segregated with BCL-[X(L)] binding. bclx(-/-) MEFs expressing BAD and bad(-/-) MEFs both arrested in G0/G1 in low serum similar to wild-type controls, suggesting that the ability to overcome the G0/G1 checkpoint resulted from the presence of BAD/BCL-x(L) heterodimers, rather than the absence of BCL-[X(L)] or BAD. These data provide evidence that in addition to regulating apoptosis, the BAD/BCL-[X(L)] heterodimer has a novel cell cycle function.

Animals↗
PubMed2001

EGF-dependent translocation of green fluorescent protein-tagged PLC-gamma1 to the plasma membrane and endosomes.

Growth factor-dependent translocation of phospholipase C-gamma1 (PLC-gamma1) was investigated using a green fluorescent protein-tagged PLC-gamma1 (PLC-gamma1-GFP) expressed in human epidermoid carcinoma A-431 cells. In the absence of growth factors, PLC-gamma1-GFP was present throughout the cytoplasm of A-431 cells. Treatment of the cells with epidermal growth factor (EGF) produced a very rapid redistribution of PLC-gamma1-GFP to the plasma membrane in a nonuniform manner. This translocation to the plasma membrane was insensitive to an inhibitor of phosphatidylinositol 3-kinase and was independent of cell adhesion. However, the translocation was disrupted by an agent which depolymerizes the actin cytoskeleton. At later times following the addition of EGF, PLC-gamma1-GFP appeared associated with intracellular vesicles. Stimulation of A-431 cells by Texas red-conjugated EGF for more than 10 min resulted in punctate intracellular PLC-gamma1-GFP distribution that colocalized with Texas red-conjugated EGF. This suggests that PLC-gamma1 is translocated to endosomes after EGF treatment, probably by associating with the internalized and autophosphorylated EGF receptor. Fractionation studies demonstrated that the EGF-induced plasma membrane-localized PLC-gamma1 is concentrated in caveolae microdomains. Disruption of caveolae with methyl-beta-cyclodextrin resulted in the ablation of EGF-induced, but not bradykinin-induced, mobilization of intracellular Ca(2+). This treatment, however, only partially decreased PLC-gamma1 membrane translocation.

Caveolae↗
PubMed2001

Spontaneous biliary perforation presenting as gastric outlet obstruction.

Spontaneous biliary perforation (SBP) is a rare, surgically correctable cause of jaundice in neonates. The presenting feature is usually biliary ascites, and in rare cases, biliary peritonitis. This article reports a case of SBP, which presented with features of gastric outlet obstruction, leading to an erroneous preoperative diagnosis. Most probably this is the first report of such an unusual presentation of SBP. The child underwent exploratory laparotomy and a bilio-enteric bypass with drainage of the right subhepatic space, which led to a prompt resolution of the symptoms.

Bile Ducts↗
PubMed2001

Cholesterol organization in membranes at low concentrations: effects of curvature stress and membrane thickness.

Cholesterol is often found distributed nonrandomly in domains in biological and model membranes and has been reported to be distributed heterogeneously among various intracellular membranes. Although a large body of literature exists on the organization of cholesterol in plasma membranes or membranes with high cholesterol content, very little is known about organization of cholesterol in membranes containing low amounts of cholesterol. Using a fluorescent cholesterol analog (25-[N-[(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-methyl]amino]-27-norcholesterol, or NBD-cholesterol), we have previously shown that cholesterol may exhibit local organization even at very low concentrations in membranes, which could possibly be attributable to transbilayer tail-to-tail dimers. This is supported by similar observations reported by other groups using cholesterol or dehydroergosterol, a naturally occurring fluorescent cholesterol analog which closely mimics cholesterol. In this paper, we have tested the basic features of cholesterol organization in membranes at low concentrations using spectral features of dehydroergosterol. More importantly, we have investigated the role of membrane surface curvature and thickness on transbilayer dimer arrangement of cholesterol using NBD-cholesterol. We find that dimerization is not favored in membranes with high curvature. However, cholesterol dimers are observed again if the curvature stress is relieved. Further, we have monitored the effect of membrane thickness on the dimerization process. Our results show that the dimerization process is stringently controlled by a narrow window of membrane thickness. Interestingly, this type of local organization of NBD-cholesterol at low concentrations is also observed in sphingomyelin-containing membranes. These results could be significant in membranes that have very low cholesterol content, such as the endoplasmic reticulum and the inner mitochondrial membrane, and in trafficking and sorting of cellular cholesterol.

4-Chloro-7-nitrobenzofurazan↗
PubMed2001

Modulation of antagonist binding to serotonin1A receptors from bovine hippocampus by metal ions.

1. The serotonin1A (5-HT1A) receptors are members of a superfamily of seven transmembrane domain receptors that couple to G-proteins. They appear to be involved in various behavioral and cognitive functions. Although specific 5-HT1A agonists have been discovered more than a decade back, the development of selective 5-HT1A antagonists has been achieved only recently. 2. We have examined the modulation of the specific antagonist [3H]p-MPPF binding to 5-HT1A receptors from bovine hippocampal membranes by monovalent and divalent metal ions. Our results show that the antagonist binding to 5-HT1A receptors is inhibited by both monovalent and divalent cations in a concentration-dependent manner. This is accompanied by a concomitant reduction in binding affinity. 3. Our results also show that the specific antagonist p-MPPF binds to all available receptors in the bovine hippocampal membrane irrespective of their state of G-protein coupling and other serotonergic ligands such as 5-HT and OH-DPAT effectively compete with the specific antagonist [3H]p-MPPF. 4. These results are relevant to ongoing analyses of the overall modulation of ligand binding in G-protein-coupled seven transmembrane domain receptors.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2001

Prevention of adrenocortical hyperactivity by dietary casein in rats exposed to forced swimming stress.

Adrenal weight, adrenal hydroxysteroid dehydrogenase activity and serum corticosterone level were significantly higher in rats fed with 5% casein diet after 7 days of swimming stress (45 min/day) as compared to their controls. All the parameters were similar to their control levels in rats receiving 20% casein diet and exposed to swimming stress. The results suggest that casein can play an important role in preventing adrenocortical hyperactivity in swimming stressed rats.

3-Hydroxysteroid Dehydrogenases↗