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Biomedical subjects

M Mukhopadhyay

Publications and source records attributed to M Mukhopadhyay.

At least 19 recordsLinked to original sources
PubMed2006

Excited state proton transfer in di-(2-hydroxy-3-formyl-5-tert butyl phenyl) methane and solvent effect.

The proton transfer reaction and the spectroscopic properties of di-(2-hydroxy-3-formyl-5-tert butyl phenyl) methane (HFPM) have been examined in different nonpolar and polar solvents at room temperature and 77 K, by means of absorption, emission and time resolved fluorescence spectroscopy. In the ground state, the primary closed form has been identified in all the nonpolar and polar solvents and the anion is detected only in presence of base in some of the polar solvents. After photoexcitation, the excited state intramolecular proton transfer (ESIPT) is indicated by a large Stokes shifted emission (approximately 10,600 cm-1) in all the nonpolar and polar solvents used, except in water and ethylene glycol (EG). The ESIPT band is likely to be originated from the enol tautomer of the HFPM. Two types of anion and H-bonded complex have been detected in the excited state. In water and EG, only anion and H-bonded complex have been detected in the excited state. At 77 K, HFPM shows phosphorescence in pure ethanol, and in n-hexane in presence of triethylamine. It has been suggested that the appearance of phosphorescence is due to the rotation of the formyl group. The measured nonradiative decay rates have always been found to dominate in the decay processes of the excited state of HFPM. Some semiempirical calculations have been undertaken to rationalize the experimental findings.

Butanes↗
PubMed2005

Proton transfer reaction of a new orthohydroxy Schiff base in some protic and aprotic solvents at room temperature and 77 K.

The ground and excited state proton transfer reactions of a new orthohydroxy Schiff base, salicylidine-3,4,7-methyl amine (SMA) has been studied by means of absorption, emission and time resolved fluorescence spectroscopy in some polar protic and aprotic solvents at room temperature and 77K. The spectral behavior of SMA has been investigated both in neutral and basic conditions. The intramolecularly hydrogen bonded enol and zwitterion have been detected in pure methanol and ethanol, the anion is detected in basic condition. At 77K, SMA shows phosphorescence in pure methanol and ethanol. From nanosecond measurements and quantum yields of fluorescence, we have estimated the decay rates of proton transfer reaction in methanol and ethanol.

Hydrogen Bonding↗
PubMed2004

Wandering ascaris coming out through the T-tube tract--a rare occurrence.

A case of ascariasis of the common bile duct in the postoperative period of cholecystectomy and choledocholithotomy with T-tube drainage is reported. The living adult wandering ascaris came out through the T-tube tract immediately after removal of the T-tube. No such previous report has been found in the available literature.

Adult↗
PubMed2003

Haemobilia due to a large gall bladder polyp.

A 61-year-old male presented with recurrent bouts of haematemesis and melaena for last 10 days. On examination, he was found anaemic and had jaundice and a mass felt in the right hypochondrium. He required multiple blood transfusions. Oesophagogastroduodenoscopic (OGD) evaluation demonstrated no lesion, no fresh bleeding noticed from ampulla of Vater. Ultrasonographic evaluation demonstrated a heterogeneous mass within the gall bladder lumen with a chink of free lumen between the mass and gall bladder wall and also dilated biliary tract. Laparotomy confirmed mass within the gall bladder lumen without any lymph node involvement at porta or any liver metastasis, and had dilated common bile duct. Cholecystectomy was carried out. The cut section of the gall bladder showed a polypoid mass (5.5 cm x 4 cm) projecting inside lumen having a haemorrhagic spot on irregular surface and which was attached with fundus of the gall bladder through a small stalk. Choledochotomy showed only blood clots within the duct-choledochoduodenostomy was also done. Histopathological examination showed adenomatous polyp with foci of carcinoma in-situ or ly without any evidence of local metastasis. Follow-up was uneventful till after 11 months.

Gallbladder Diseases↗
PubMed2002

Cloning, genomic organization and expression pattern of a novel Drosophila gene, the disco-interacting protein 2 (dip2), and its murine homolog.

We report the cloning and initial characterization of a novel gene encoding the Disco interacting protein 2 (Dip2). dip2 DNA complementary to RNA (cDNA) showed a high degree of sequence similarity to cDNAs of unknown function previously identified in humans and Caenorhabditis elegans. We have cloned the mouse homolog of the dip2 cDNA and characterized the expression of this gene by Northern blotting analysis and in situ hybridization to whole mount embryos. Our observations demonstrate that there is a remarkable degree of sequence conservation at the dip2 locus that is reflected in the nervous system-specific expression of both the Drosophila and mouse homologs.

Amino Acid Sequence↗
PubMed2002

Is propess a better method of induction of labour in nulliparous women.

Slow release prostaglandin pessary (propess) is compared with instant release prostaglandin gel (prostin) for the induction of labour in nulliparous women with a modified Bishop's score of less than 6. In this randomised study 50 women received prostin gel and 45 received propess. More than one dose of prostaglandin was required to achieve amniotomy more often in the propess group (53%) compared with the prostin group (34%) (P=0.03). Propess was unable to demonstrate any advantage over Prostin gel group. Propess was not cost-effective in this study.

Delayed-Action Preparations↗
PubMed2001

Expression screening for Lhx3 downstream genes identifies Thg-1pit as a novel mouse gene involved in pituitary development.

Thg-1pit, a novel mouse gene, was detected in a screen for genes that are differentially expressed in the developing pituitary of wild-type and Lhx3 null mutant embryos. The predicted translation product of the Thg-1pit gene contains a C-terminal TSC-box adjacent to a leucine zipper motif. These features are characteristic for the TSC-22/DIP/bun family of proteins. The onset of prominent Thg-1pit expression coincides with Lhx3 activation at early stages of pituitary development. Expression is further enhanced as cells begin to differentiate within the developing pituitary gland. No expression is observed in the pituitary rudiment of mutants that lack Lhx3 function. A possible role is thus suggested for Lhx3 activities in the regulation of Thg-1pit function during early steps of pituitary organogenesis.

Amino Acid Sequence↗
PubMed2001

Clinical appraisal of Ascaris lumbricoides, with special reference to surgical complications.

Over a period of 4 years (January 1993-December 1997), 509 patients were treated for abdominal colic with or without intestinal obstruction and a history of passage of adult roundworms either in the stool or in vomitus. All patients were below the age of 10 years, the youngest 6 months old, and were treated successfully with antispasmodics and normal saline enemas. When the pain subsided, an anthelminthic drug was given. Of 209 patients admitted to the hospital, 105 responded to conservative management and 104 (50%) required surgical intervention. The procedures included squeezing out of worms, resection and anastomosis, and treatment of other pathologies like acute appendicitis, tubercular stricture of the small intenstine, etc. Five patients died in the postoperative period due to various complications. There were no deaths among those treated by conservative management. Early recognition of the condition can prevent serious surgical complications and morbidity.

Animals↗
PubMed2001

Myocardial tumor necrosis factor-alpha expression does not correlate with clinical indices of heart failure in patients on left ventricular assist device support.

BACKGROUND: Mechanical unloading with a left ventricular assist device (LVAD) can improve clinical indices of heart failure and alter myocardial tumor necrosis factor-alpha (TNFalpha) expression, but a correlation between clinical and molecular indices has not been established. METHODS: We enrolled 14 patients with end-stage heart failure treated with drugs and mechanical unloading in a protocol including the collection of myocardial tissue samples at LVAD implantation and explantation. Ten nonfailing donor hearts served as controls. TNFalpha expression was measured by quantitative reverse transcription polymerase chain reaction. Clinical indices of heart failure were retrospectively analyzed and correlated with myocardial TNFalpha expression. RESULTS: Left ventricular end-diastolic dimension decreased (p < 0.01) and cardiac index (p < 0.001) increased with unloading. Abnormal values of serum sodium, creatinine, blood urea nitrogen, glutamic-oxaloacetic transaminase, glutamic-pyruvic transaminase, and albumin showed a trend toward normalization with mechanical unloading. TNFalpha expression was increased in 5 of 14 patients and decreased with mechanical unloading in 4 of them. Surprisingly, there was no correlation between mRNA levels of TNFalpha and any of the clinical indices studied. CONCLUSIONS: Although clinical indices of heart failure improve and elevated levels of myocardial TNFalpha expression decrease with mechanical unloading, there is no correlation between the two. Thus, clinical and molecular indices of heart failure in LVAD-supported patients do not always correlate.

Adolescent↗
PubMed2001

Dickkopf1 is required for embryonic head induction and limb morphogenesis in the mouse.

Dickkopf1 (Dkk1) is a secreted protein that acts as a Wnt inhibitor and, together with BMP inhibitors, is able to induce the formation of ectopic heads in Xenopus. Here, we show that Dkk1 null mutant embryos lack head structures anterior of the midbrain. Analysis of chimeric embryos implicates the requirement of Dkk1 in anterior axial mesendoderm but not in anterior visceral endoderm for head induction. In addition, mutant embryos show duplications and fusions of limb digits. Characterization of the limb phenotype strongly suggests a role for Dkk1 both in cell proliferation and in programmed cell death. Our data provide direct genetic evidence for the requirement of secreted Wnt antagonists during embryonic patterning and implicate Dkk1 as an essential inducer during anterior specification as well as a regulator during distal limb patterning.

Animals↗
PubMed2001

A biographical sketch of Lewis Dexter.

Dr. Lewis Dexter was an outstanding cardiovascular physiologist and clinician, a respected teacher and scientist, and, most importantly, a fine human being. During his life, he brought the cardiac catheter from the laboratory to the patient and trained several generations of cardiologists. Dexter's laboratory was the first to elucidate the pathophysiologic alterations present in many forms of congenital heart disease, including atrial septal defects, patent ductus arteriosus, tetralogy of Fallot, ventricular septal defects, and pulmonic stenosis. Subsequent work in Dexter's laboratory led to the 1st measurements of pulmonary capillary wedge pressure and to the precise calculation of stenotic valve areas from hemodynamic parameters measured during cardiac catheterization. During a teaching exercise, Dexter demonstrated that exercise with a cardiac catheter in the heart was safe and produced clinically important data, by having a cardiac catheter inserted in himself. Over the years, many significant pathophysiologic studies that explored pulmonary embolism, valvular heart disease, right and left ventricular function, and pulmonary hypertension were published from Dexter's laboratory. But Lewis Dexter was more than a brilliant researcher "Lew" was very close to his fellows and students, whom he considered extensions of his family Dexter was a remarkable teacher, a compassionate physician, and a scrupulously honest investigator. Dr Lewis Dexter had a major impact on modern medicine and was one of the great cardiologists of the 20th century.

Cardiology↗
PubMed2001

Comparative evaluation of hydrophobicity measures for virulence determination of Staphylococcus epidermidis from hospitalized patients & healthy individuals.

BACKGROUND & OBJECTIVES: Hydrophobicity is one of the recognized markers for identifying pathogenic strains of Staphylococcus epidermidis. A number of tests are available for measuring the hydrophobic character but three tests viz., salt aggregation test (SAT), n-hexadecane adherence assay (HAA) and xylene adherence assay (XAA) are in common practice with different degrees of sensitivity. However, in the Indian context, no systematic study has been reported on the hydrophobicity of S. epidermidis. Hence, the present study was undertaken to compare the three methods for hydrophobicity measurement for identifying the pathogenic isolates of S. epidermidis. METHODS: Of the 597 samples obtained from milker's and butcher's (hand and nose), hospitalized pre-operative patients (hand, nose, ear), and post-operative patients (blood) examined, 212 isolates of S. epidermidis were recovered using established laboratory procedures. The isolates were screened by the three tests viz., SAT, HAA and XAA. The identified hydrophobic isolates were further tested by mouse inoculation method. RESULTS: Of the 212 S. epidermidis isolates studied, 24 (11.32%), 23 (10.84%) and 4 (1.88%) were found to be hydrophobic as detected by HAA, XAA and SAT, respectively. No isolates from apparently healthy individuals were found to be hydrophobic by SAT while 13 (8.76%) and 10 (8.24%) strains from apparently healthy individuals were detected to be hydrophobic by HAA and XAA, respectively. Seven (33.38%) isolates each were hydrophobic by HAA and XAA and 4 (22.22%) by SAT among the isolates from hospitalized post-operative patients. INTERPRETATION & CONCLUSION: The results suggested that there was no difference in the number of strains detected as hydrophobic by HAA and XAA, and any of the two tests may be used for screening the hydrophobic strains of S. epidermidis from healthy individuals and patients.

Bacteriological Techniques↗
PubMed2000

In vivo cytogenetic studies on blends of aspartame and acesulfame-K.

Aspartame and acesulfame-K, non-nutritive sweeteners, are permitted individually in diets and beverages. These sweeteners of different classes, used in combination, have been found to possess a synergistic sweetening effect. Whether they also have a synergistic genotoxic effect is unknown. Swiss Albino male mice were exposed to blends of aspartame (3.5, 35, 350mg/kg body weight) and acesulfame-K (1.5, 15 and 150mg/kg body weight) by gavage. Bone marrow cells isolated from femora were analysed for chromosome aberrations. Statistical analysis of the results show that aspartame in combination with acesulfame-K is not significantly genotoxic.

Animals↗
PubMed1999

Autoregulation of the Drosophila disconnected gene in the developing visual system.

The Drosophila disconnected (disco) gene is required for the formation of appropriate connections between the larval optic nerve and its target cells in the brain. The disco gene encodes a nuclear protein with two zinc fingers, which suggests that the gene product is a transcription factor. Here, we present data supporting this notion. We find that disco expression in the optic lobe primordium, a group of cells contacted by the developing optic nerve, depends on an autoregulatory feedback loop. We show that wild-type disco function is required for maintenance of disco mRNA and protein expression in the developing optic lobe. In addition, we demonstrate that ubiquitous Disco activity supplied by a heat-inducible gene construct activates expression from the endogenous disco gene specifically in the optic lobe primordium. Consistent with a role of Disco as a transcriptional regulatory protein, we show that portions of the Disco protein are capable of activating the transcription of reporter constructs in a heterologous system. Moreover, we find that the zinc finger portion of Disco binds in vitro to sequences located near the disco transcription unit, suggesting that Disco autoregulates its transcription in the optic lobe primordium by direct binding to a regulatory element in its own promoter.

Animals↗
PubMed1998

Effect of calcium-channel blocking drugs on focal ventricular arrhythmias induced by sub-epicardial epinephrine infusion in cats.

Sub-epicardial infusion of epinephrine (EP) in the dose of 3 x 10(-3) M in 2.5 x 10(-3) M CaCl2-0.9% NaCl (calcium-saline vehicle) at the rate of 10 microliters in the right ventricular myocardium of mongrel cats weighing between 2.8 and 3.3 kg, produced uniform, reversible and reproducible focal ventricular arrhythmia (VA) of varrying intensity and duration. Infusion of two calcium-channel blocking agents, verapamil (VP) and nifedipine (ND) at the site of arrhythmogenesis, in equimolar concentration of 3 x 10(-3) M alongwith EP in the same vehicle reduced the incidence, duration, peak and mean frequencies of arrhythmias while, the latent period of onset of arrhythmias increased significantly. Verapamil in equimolar concentration of 3 x 10(-3) M was found to be more effective than nifedipine in antagonizing EP-induced ventricular arrhythmias.

Animals↗
PubMed1997

NADPH-initiated cytochrome P450-dependent free iron-independent microsomal lipid peroxidation: specific prevention by ascorbic acid.

In this paper we demonstrate that ascorbic acid specifically prevents NADPH-initiated cytochrome P450 (P450)-mediated microsomal lipid peroxidation in the absence of free iron. Lipid peroxidation has been evidenced by the formations of conjugated dienes, lipid hydroperoxide and malondialdehyde. Other scavengers of reactive oxygen species including superoxide dismutase, catalase, glutathione, alpha-tocopherol, uric acid, thiourea, mannitol, histidine, beta-carotene and probucol are ineffective to prevent the NADPH-initiated P450-mediated free iron-independent microsomal lipid peroxidation. Using a reconstituted system comprised of purified NADPH-P450 reductase, P450 and isolated microsomal lipid or pure L-alpha-phosphatidylcholine diarachidoyl, a mechanism has been proposed for the iron-independent microsomal lipid peroxidation and its prevention by ascorbic acid. It is proposed that the perferryl moiety P450 Fe3+.O2.- initiates lipid peroxidation by abstracting methylene hydrogen from polyunsaturated lipid to form lipid radical, which then combines with oxygen to produce the chain propagating peroxyl radical for subsequent formation of lipid peroxides. Apparently, ascorbic acid prevents initiation of lipid peroxidation by interacting with P450 Fe3+.O2.-.

Animals↗
PubMed1995

The larval optic nerve is required for the development of an identified serotonergic arborization in Drosophila melanogaster.

The larval visual system in the fruitfly Drosophila melanogaster consists of two bilateral clusters of 12 photoreceptor cells. These neurons send their axons in a fascicle, the Bolwig's nerve, toward the target area in the ventral lateral region of the brain hemispheres. We describe the development of a serotonergic arborization originating in the central brain found in the larval optic center in association with the larval optic nerve. This arborization is formed by processes from larval neurons born during embryogenesis. However, these neuronal processes do not reach their final destination, the larval optic center, until late in larval development. Using mutations that disrupt the connectivity and/or development of the larval photoreceptor cells, as well as mosaic analysis, we demonstrate that the innervation of the larval optic center by this serotonergic arborization depends upon contact with the larval optic nerve.

Animals↗