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Biomedical subjects

M Mukherjee

Publications and source records attributed to M Mukherjee.

At least 37 records · Page 2Linked to original sources
PubMed2001

SMN2-deletion in childhood-onset spinal muscular atrophy.

The human genome has two homologous survival motor neuron genes, SMN1 and SMN2. Although deletions of SMN1 are frequently reported in childhood-onset spinal muscular atrophy (SMA), SMN2 have been found to be intact in patients with the disorder. We report on a 5-year-old boy with childhood-onset SMA who has a homozygous deletion of SMN2. He had wasting, weakness, and hyporeflexia, predominantly in the distal muscles. The muscles involved showed chronic neurogenic changes on electromyogram. There was no sensory involvement. A nerve conduction study showed near normal conduction velocity with reduction in the amplitude of the compound muscle action potential. Analysis of polymerase chain reaction-restriction fragment length polymorphism as well as single-strand conformation polymorphism on exons 7 and 8 of the SMN genes revealed the SMN2-deletion. Base sequencing and densitometric analysis of the critical region (exon 7) did not show any microdeletion or duplication of SMN1, but confirmed the deletion of SMN2. We conclude that a deletion of SMN2 may also result in the SMA phenotype.

Child↗
PubMed2001

Purification and characterization of a growth-regulating laccase from Pleurotus florida.

Pleurotus florida produces two laccase enzymes (L1 and L2) within which L2 is associated with the vegetative growth of the fungus. In the present investigation the L2 has been purified to homogeneity and characterized. The molecular mass of the enzyme has been determined to be 73 kDa and 70 kDa by gel filtration chromatography and SDS-PAGE, respectively. The purified enzyme shows a pI value of 4.2. The optimum reaction temperature is 50 degrees C. Spectroscopic analysis reveals that L2 has two copper atoms, a type I copper and a type II copper. The Km and some other kinetic parameters of L2 has been determined.

Amino Acid Sequence↗
PubMed2001

Carrier detection in non-deletional Duchenne/Becker muscular dystrophy families using polymorphic dinucleotide (CA) repeat loci of dystrophin gene.

BACKGROUND & OBJECTIVES: Carrier detection and prenatal diagnosis is of great importance for families with one or more sons affected with Duchenne/Becker muscular dystrophy (D/BMD). In about 35-40 per cent of these patients, the causative mutation does not involve gross rearrangement in the structure of dystrophin gene. In these non-deletional families, genetic counselling can be provided only by linkage analysis. The aim of the present study was to determine the carrier status of female relatives in north Indian families with non-deletional D/BMD using highly polymorphic intragenic dinucleotide (CA) repeat markers. METHODS: Six short tandem repeats (STRs) spanning 5' (1), central (4) and 3' regions of the dystrophin gene were used to analyse 14 unrelated families comprising 68 individuals with 12 female siblings at risk of being carriers. RESULTS: Five female siblings inherited at risk STR haplotype, six inherited normal haplotype and one had meiotic recombination. The intragenic recombinations were observed in three families at the central region STR loci and in one family between the proximal and central regions of the gene. INTERPRETATION & CONCLUSIONS: Our study suggested that at least 6 STR markers spanning 5', central and 3' regions of the dystrophin gene are essential to ascertain one or more informative loci and to rule out recombinations in non-deletional D/BMD families for carrier analysis.

Dinucleotide Repeats↗
PubMed2000

Deregulation of glucose transporter 1 and glycolytic gene expression by c-Myc.

Unlike normal mammalian cells, which use oxygen to generate energy, cancer cells rely on glycolysis for energy and are therefore less dependent on oxygen. We previously observed that the c-Myc oncogenic transcription factor regulates lactate dehydrogenase A and induces lactate overproduction. We, therefore, sought to determine whether c-Myc controls other genes regulating glucose metabolism. In Rat1a fibroblasts and murine livers overexpressing c-Myc, the mRNA levels of the glucose transporter GLUT1, phosphoglucose isomerase, phosphofructokinase, glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, and enolase were elevated. c-Myc directly transactivates genes encoding GLUT1, phosphofructokinase, and enolase and increases glucose uptake in Rat1 fibroblasts. Nuclear run-on studies confirmed that the GLUT1 transcriptional rate is elevated by c-Myc. Our findings suggest that overexpression of the c-Myc oncoprotein deregulates glycolysis through the activation of several components of the glucose metabolic pathway.

Animals↗
PubMed2000

Purification and characterization of laccase-1 from Pleurotus florida.

Pleurotus florida (ITCC 3308) produces two laccase enzymes (L1 and L2) in potato-dextrose media containing 0.5% yeast extract. Concentrated culture filtrate was separated on DEAE-Sephadex (A-50) column into two enzyme peaks, subsequently named L1 and L2. The L1 enzyme has been purified to homogeneity by ion-exchange and gel-permeation chromatography. L1 is a monomeric glycoprotein with a molar mass of 77 and 82 kDa as determined by SDS-PAGE and gel-filtration chromatography, respectively. The pI value of L1 has been determined to be 4.1. The optimum reaction temperature of the enzyme is 50 degrees C. The Km and some other kinetic parameters of L1 have been determined. Cyanide and azide completely inhibit the enzyme activity. The enzyme was fully active in 1:1 (V/V) buffer-chloroform for at least 2 h. Spectroscopic analysis revealed that the enzyme has four copper atoms, a type 1 copper, a type 2 copper and a type 3 binuclear copper.

Copper↗
PubMed2000

Accumulation of a natural substrate of laccase in gills of Pleurotus florida during sporulation.

During sporulation, laccase activity of Pleurotus florida decreased to a minimum level in spite of increase in the number of isozymes. An endogenous laccase substrate was detected especially in the gill structure of the sporophore, which competitively inhibited oxidation of guaiacol by the enzyme during in vitro assay. Appearance of the laccase substrate in the gill structure may be linked with the sporulation phenomenon.

Guaiacol↗
PubMed2000

(E)-2-[2-(1-Naphthyl)vinyl]-3-tosyl-2,3-dihydro-1,3-benzothiazole.

The title compound, C(26)H(21)NO(2)S(2), which consists of a benzothiazole skeleton with alpha-naphthylvinyl and tosyl groups at positions 2 and 3, respectively, was prepared by palladium-copper-catalyzed heteroannulation. The E configuration of the molecule about the vinyl C=C bond is established by the benzothiazole-naphthyl C-C-C-C torsion angle of 177.5 (4) degrees. The five-membered heterocyclic ring adopts an envelope conformation with the Csp(3) atom 0.380 (6) A from the C(2)NS plane. The two S-C [1.751 (4) and 1.838 (4) A] and two N-C [1.426 (5) and 1.482 (5) A] bond lengths in the thiazole ring differ significantly.

Benzothiazoles↗
PubMed2000

Bis

In the title compound, [Zn(C(8)H(10)N(3)O(2))(2)], the Zn atom displays a highly distorted octahedral coordination involving O and N atoms of two bidentate planar ligands approximately orthogonal to each other; the dihedral angle between the ligand planes is 84.95 (4) degrees. The ligand molecules show great asymmetry in their bonding to the Zn(2+) ion, with Zn-O bond distances ranging between 2.056 (2) and 2.534 (2) A. The planar phenyl ring and the trigonal-planar geometry about the triazene N atom bonded to the phenyl ring suggest a resonance interaction extending over adjacent atoms.

Journal Article↗
PubMed2000

A direct-method ab initio phasing of a protein, pseudoazurin, at 1.55 A resolution.

The direct-method program MULTAN88 has been applied to solve a known protein, pseudoazurin, space group P6(5), unit-cell parameters a = b = 50.0 (1), c = 98.5 (3) A, with 917 protein atoms, a Cu atom and 93 solvent water molecules in the asymmetric unit (>6,000 non-H atoms in the unit cell) and data at 1.55 A resolution. One of several trials with sets of initially random phases yielded phase estimates for 1,000 reflections with a mean phase error of 68.3 degrees that was recognized as the best available solution by the figure of merit being used. Phase extension to 2,000 largest Es showed a distorted tetrahedral geometry around the Cu site. Density modification was applied to improve the phases and the quality of the maps, starting with phases calculated from the atomic positions indicated by the first map.

Azurin↗
PubMed2000

HMG-I/Y, a new c-Myc target gene and potential oncogene.

The HMG-I/Y gene encodes the HMG-I and HMG-Y proteins, which function as architectural chromatin binding proteins important in the transcriptional regulation of several genes. Although increased expression of the HMG-I/Y proteins is associated with cellular proliferation, neoplastic transformation, and several human cancers, the role of these proteins in the pathogenesis of malignancy remains unclear. To better understand the role of these proteins in cell growth and transformation, we have been studying the regulation and function of HMG-I/Y. The HMG-I/Y promoter was cloned, sequenced, and subjected to mutagenesis analysis. A c-Myc-Max consensus DNA binding site was identified as an element important in the serum stimulation of HMG-I/Y. The oncoprotein c-Myc and its protein partner Max bind to this site in vitro and activate transcription in transfection experiments. HMG-I/Y expression is stimulated by c-Myc in a Myc-estradiol receptor cell line in the presence of the protein synthesis inhibitor cycloheximide, indicating that HMG-I/Y is a direct c-Myc target gene. HMG-I/Y induction is decreased in Myc-deficient fibroblasts. HMG-I/Y protein expression is also increased in Burkitt's lymphoma cell lines, which are known to have increased c-Myc protein. Like Myc, increased expression of HMG-I protein leads to the neoplastic transformation of both Rat 1a fibroblasts and CB33 cells. In addition, Rat 1a cells overexpressing HMG-I protein form tumors in nude mice. Decreasing HMG-I/Y proteins using an antisense construct abrogates transformation in Burkitt's lymphoma cells. These findings indicate that HMG-I/Y is a c-Myc target gene involved in neoplastic transformation and a member of a new class of potential oncogenes.

Animals↗
PubMed2000

Anticoagulant versus amidolytic activity of tissue factor pathway inhibitor in coronary artery disease.

In view of raised levels of endothelial markers in coronary artery disease (CAD), the aim of the present study was to investigate the status of tissue factor pathway inhibitor (TFPI), another endothelium-associated glycoprotein and coagulation protease inhibitor, in CAD. The intravascular pool of TFPI is heterogeneous with respect to assay-dependent activity. While the standard amidolytic assay works well with both full-length and truncated (lipoprotein-associated) TFPI, the anticoagulant assay works better with the former. The anticoagulant activity of TFPI can be estimated using dilute tissue factor (TF) to trigger clotting of plasma. In the present study, recombinant TF diluted 2,000-fold was used to initiate coagulation. A dose-dependent shortening of clotting time of normal plasma pools with polyclonal antibody against the C-terminal but not the N-terminal peptide of TFPI demonstrated the importance of the C-terminal region, and hence that of full-length TFPI, in conferring its anticoagulant activity, corroborating current opinion. As a further confirmation, the C-terminal peptide itself prolonged dilute TF clotting time of normal pooled plasma in a concentration-dependent manner. The amidolytic and anticoagulant activities of TFPI were determined in 20 patients with clinically and angiographically assessed CAD and in 68 asymptomatic controls. The mean +/- SD ages of patients and controls were 54.9 +/- 10.3 and 48.8 +/- 11.6 years, respectively, the difference being statistically significant (P = 0.04). The mean TFPI activity measured by amidolytic assay was comparable for patients and controls (1.2 +/- 0.3 and 1.3 +/- 0.5 U/ml, respectively). However, the dilute TF clotting time was 115 +/- 26 s in patients, against 99 +/- 10 s in controls (P < 0.0001, irrespective of age adjustment). Since none of the patients had received heparin or had coagulation factor deficiency that may interfere with the assay, prolongation of clotting time may be attributed to the presence of TFPI, particularly the full-length form. To verify this inference, 33 extra aliquots left over from 88 samples (62.5%), 21 from controls and 12 from patients, were incubated with 1:10 diluted antibody against the C-terminal peptide of TFPI prior to dilute TF assay. The mean clotting time of both patients and controls decreased, and the between-group difference leveled (90 +/- 10 versus 88 +/- 20 s for controls and patients, respectively; P = 0.841). The mean drop in clotting time was 9% for the controls and 24% for the patients. This illustrates the specificity of dilute TF assay for full-length TFPI and supports the conclusion that relative to lipoprotein-associated TFPI, the proportion of the full-length form was possibly greater in patients with CAD. Contribution of lipoprotein-associated TFPI to the overall anticoagulant activity by its activated factor X-dependent inhibition of activated factor VII-TF complex seems less important considering the similar between-group mean amidolytic activities.

Anticoagulants↗
PubMed2000

Role of dopamine in the modulation of adrenal gland responses in the osmotically stressed pigeons, Columba livia.

Salt loading on pigeons (C. livia) had stimulatory effects on brain amines (dopamine and 5-hydroxytryptamine), corticosterone, norepinephrine and epinephrine contents of adrenal gland. Conjoint administration of dopamine with hypertonic saline restored the brain amines and corticosterone of adrenal gland, but had no effect on catecholamine (CAM) contents of adrenal medulla. The excessive release of CAM in the plasma indicates sympathetic stimulation after both the treatments.

Adrenal Glands↗
PubMed1999

On the application of phase relationships to complex structures. XXXVI: some experiments with a small protein without heavy atoms.

The direct-methods program MULTAN88 has been applied to a known protein, ribonuclease (RNAP1), containing 808 non-H atoms, including five S atoms, plus 83 ordered solvent water molecules. Phase sets with mean phase errors between 69 and 75 degrees were selected by modified figures of merit for trials with the full data at 1.17 A resolution and also with restricted data at 1.25 and 1.5 A resolution. These figures of merit had previously only been applied to protein structures containing heavy atoms, and this is the first demonstration of their usefulness with no heavy atom present. An initial set of 1091 phases from a 1.17 A trial was developed by an objective procedure to give the full structure with a residual of 0. 21, which agrees well with the published structure.

Crystallography, X-Ray↗
PubMed1999

Haemodynamic responses and changes of haemostatic risk factors in cold-adapted humans.

Epidemiological studies have shown an increase in acute myocardial infarctions or deaths due to myocardial infarction in colder weather; the mechanisms most likely involve increased blood levels of haemostatic risk factors, and increases in arterial blood pressure and heart rate. We studied the relationship between cold adaptation, haemostatic risk factors and haemodynamic variables. Cold adaptation was obtained by a programme of immersion of the whole body up to the neck in a water-filled bath, the temperature of which was gradually decreased from 22 degrees C to 14 degrees C, time of exposure being increased from 5 to 20 min over a period of 90 days. We studied 428 patients (44% men) and measured blood levels of fibrinogen, plasminogen activator inhibitor 1 (PAI-1), tissue plasminogen activator antigen (t-PA), plasma viscosity, von Willebrand factor, D-dimer and platelet count, both at baseline and after 90 days of daily immersion. There were significant reductions in von Willebrand factor (-3%; p < 0.001), and plasma viscosity (-3.0 s; p < 0.001), and a mild but significant increase in PAI-1 (+0.3 IU/ml; p = 0.02). The pressure rate product (systolic blood pressure x heart rate) was also significantly lower after cold adaptation (-310; p = 0.004). Cold adaptation, compared with exposure to cold weather, induces different haemodynamic responses and changes of blood levels of haemostatic risk factors.

Acclimatization↗
PubMed1999

Ab initio structure determination of a small protein, rubredoxin, by direct methods.

The direct-methods program SAYTAN has been applied successfully to a known protein, rubredoxin, which contains 52 amino-acid residues including an FeS4 unit, a sulfate ion and 102 solvent water molecules. Starting with initially random phases, useful sets can be obtained from multiple trials and selected by figures of merit at different resolutions. Phase extension followed by weighted Fourier recycling reveals a recognizable structure of rubredoxin. The model is refined against 1 A resolution data to an R factor of 14.5% using the program SHELXL93.

Bacterial Proteins↗
PubMed1999

A comparative study on the Mitsuda type response to antigens of chemoautotrophic nocardioform bacteria and to standard lepromin in leprosy patients.

Anergy, or contrarily, Mitsuda-type responses towards 4 chemoautotrophic nocardioform antigens (CAN-Ags) and a control standard lepromin were tested in 73 LL, TT and borderline cases of leprosy. The antigens injected per patient varied from a maximum of 5 to a minimum of 2. Complete anergy to CAN-Ags was seen in 92/92 instances tested on 24 LL cases. The anergy was weakly modified or unmodified in 3 other LL cases which had been vaccinated before. Concurrent studies with the same antigens tested on 33 TT cases showed clear-cut, dose-dependent, Mitsuda-type late responses in 80/81 instances. The CAN bacteria, therefore, despite their origin from different unrelated leprous human, mouse footpad (MFP) and armadillo tissues, appeared to be identical with each other and also probably related to the leprosy bacillus, on the basis of these parameters.

Actinomycetales↗