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D Mitra

Publications and source records attributed to D Mitra.

54 records · Page 3Linked to original sources
PubMed1992

Immunochemical studies on the combining site of the A + N blood type specific Moluccella laevis lectin.

The specificity of the anti A+N lectin of Moluccella laevis (MLL) was examined by hemagglutination experiments with enzyme-modified human erythrocytes and by inhibition of hemagglutination. In addition, binding to various glycoproteins and inhibition by different sugars and glycoproteins were examined by enzyme immunoassay with antibodies to the lectin. Treatment of AMM erythrocytes with proteolytic enzymes increased their agglutinability by MLL 4-16-fold; similar treatment of ONN cells decreased their agglutinability 8-16-fold. This is in line with the known location and enzyme sensitivity of A and N specificity determinants. Treatment of the erythrocytes with sialidase increased their agglutinability and abolished the distinction between N and M cells. Hapten inhibition of hemagglutination of AMM and ONN erythrocytes by the lectin, and its binding to glycoproteins measured by enzyme immunoassay, confirmed the high specificity of MLL for N-acetyl-D-galactosamine (200-500 times more than for D-galactose) and suggested the presence of hydrophobic interactions around HO-2 of the D-galactose unit. The methyl alpha-glycosides of D-galactose and of N-acetyl-D-galactosamine were better inhibitors than the corresponding beta-glycosides; this preference was abolished, and sometimes reversed, when the p-nitrophenyl glycosides of the same monosaccharides were tested, stressing again the importance of hydrophobic interactions in the binding of carbohydrates to MLL. The lectin reacted well with ONN substance and with glycophorin A of the N phenotype (GPAN), but did not react with OMM substance or GPAM. The strongest inhibitor was asialo ovine submaxillary mucin, which contains many unsubstituted alpha-D-GalpNAc-(1-->3)-Ser/Thr residues; calculated per N-acetyl-D-galactosamine residue, it was 1500 stronger than free N-acetyl-D-galactosamine. In accordance with this result, it was found that the lectin strongly agglutinates Tn cells. The specificity of MLL can, thus, be defined as anti-Tn, crossreactive with blood types A and N, and with sialosyl-Tn. The N-specificity can best be explained by assuming that GPAN contains a small number of unsubstituted or partially sialylated alpha-D-GalpNAc-(1-->3)-Ser/Thr residues, which are present in smaller proportions, if at all, in GPAM.

Antibody Specificity↗
PubMed1989

Physicochemical studies of binding of 4-methylumbelliferyl beta-D-galactopyranoside to cold agglutinin.

The fluorescence of 4-methylumbelliferyl beta-D-galactopyranoside (MeUmbGalp) was quenched in the presence of cold agglutinin, showing that there was binding between MeUmbGalp and cold agglutinin. That binding was saccharide-specific. By using this quenching phenomenon, the association constants (Ka) of the binding of cold agglutinin at different temperatures (10 degrees C and 15 degrees C) to MeUmbGalp and also the number of binding sites were calculated. The Ka values were found to be 2.63 x 10(3) M-1 at 10 degrees C and 1.58 x 10(3) M-1 at 15 degrees C. Though there is a change in Ka values, the number of binding sites was calculated to be six at both temperatures (10 degrees C and 15 degrees C). From the Ka values the thermodynamic parameters (free energy, enthalpy and entropy) of the binding were derived, and analysis of the data indicated that the binding is spontaneous, exothermic and hydrophobic in nature.

Agglutinins↗
PubMed1988

A galactose specific agglutinin from the hemolymph of the snail Achatina fulica: purification and characterization.

A galactose specific agglutinin has been detected in the hemolymph of the snail Achatina fulica fulica Bowdich. The agglutinin, which agglutinates rabbit erythrocytes, has been purified by affinity chromatography on crosslinked guargum followed by gel filtration on a Biogel P-200 column. The purified agglutinin has a native molecular weight of 210,000 and comprises of non covalently linked identical subunits of molecular weight 15,000. The pI of the agglutinin was found to be 8.1. The activity of the agglutinin is independent of divalent cations. The inhibition of hemagglutination data reveals that 2-deoxy-D-galactose is the most potent inhibitor of the agglutinin followed by galactose and lactose.

Animals↗
PubMed1988

Purification and characterization of an agglutinin from mucus of the snail Achatina fulica.

The mucus of the snail Achatina fulica shows the presence of an agglutinin that nonspecifically agglutinates human erythrocytes. The agglutinin has been purified by affinity chromatography using Sepharose 4B-hog gastric mucin as the affinity matrix. Homogeneity was checked by polyacrylamide gel electrophoresis, immunodiffusion, immunoelectrophoresis, and gel filtration. The agglutinin is a glycoprotein of native molecular weight 70,000. The isoelectric point of the protein was found to be 8.0. The predominant amino acids are aspartic acid and glutamic acid (or amides) and serine, which account for 32% of the total amino acid residues. The agglutinin has 10% carbohydrate (wt/wt) and the most abundant sugar is N-acetylglucosamine. The cd spectra of the agglutinin show the presence of random coil conformation. The inhibition of hemagglutination data indicates that the agglutinin is specific for beta glycosides of D-Gal and D-GalNAc.

Agglutinins↗
PubMed1987

Studies on chemical modification of cold agglutinin from the snail Achatina fulica.

The cold agglutinin isolated from the albumin gland of the snail Achatina fulica was modified with various chemical reagents in order to detect the amino acids and/or carbohydrate residues present in its carbohydrate-binding sites. Treatment with reagents considered specific for modification of lysine, arginine and tryptophan residues of the cold agglutinin did not affect the carbohydrate-binding activity of the agglutinin. Modification of tyrosine residues showed some change. However, modification with carbodiimide followed by alpha-aminobutyric acid methyl ester causes almost complete loss of its binding activity, indicating the involvement of aspartic acid and glutamic acid in its carbohydrate-binding activity. The carbohydrate residues of the cold agglutinin were removed by beta-elimination reaction, indicating that the sugars are O-glycosidically linked to protein part of the molecule. Removal of galactose residues from the cold agglutinin by the action of beta-galactosidase indicated that the galactose molecules are beta-linked. These carbohydrate-modified glycoproteins showed a marked change in agglutination property, i.e. they agglutinated rabbit erythrocytes at both 10 degrees C and 25 degrees C, indicating that the galactose residues of the glycoprotein play an important role in the cold-agglutination property of the glycoprotein. The c.d. data showed the presence of an almost identical type of random-coil conformation in the native cold agglutinin at 10 degrees C and in the carbohydrate-modified glycoprotein at 10 degrees C and 25 degrees C. This particular random-coil conformation is essential for carbohydrate-binding property of the agglutinin.

Agglutinins↗
PubMed1987

Further characterization of the cold agglutinin from the snail Achatina fulica.

The cold agglutinin from the albumin gland of the snail Achatina fulica was purified to homogeneity by using sheep gastric mucin-Sepharose 4B as affinity column followed by gel filtration on Bio-Gel P-300. The homogeneity was checked by alkaline gel electrophoresis, immunodiffusion and immunoelectrophoresis. The purified cold agglutinin is a glycoprotein of native M2 220,000 consisting of three non-covalently bound subunits of Mr 84,000, 74,000 and 62,000 and having a pI value of 4.5. The predominant amino acids are aspartic acid and glutamic acid (or amides) and serine, which account for 39% of the residues. About 3% of the residues are half-cystine. The lectin is a glycoprotein with about 30.7% carbohydrate, the most abundant sugars being galactose, N-acetylgalactosamine and N-acetylglucosamine. Mannose, xylose and fucose are also present. The inhibition of agglutination of human umbilical-cord erythrocytes by the cold agglutinin is specific for methyl beta-D-galactoside and also for glycolipids present on cord erythrocytes. The c.d. data show only negative ellipticity values in the far-u.v. region for the protein at various concentrations and temperatures and also in the presence of the hapten lactose (at different concentrations), indicating the presence of a random-coil conformation in the agglutinin that varies according to temperature.

Agglutinins↗
PubMed1984

A new 4-nitrophenol 2-hydroxylase from a Nocardia sp.

A new enzyme which can hydroxylate 4-nitrophenol to 4-nitrocatechol has been isolated from a Nocardia sp. It is an inducible enzyme found in the 105,000xg supernatant. It requires molecular oxygen, reduced pyridine nucleotide, and flavin adenine dinucleotide for its activity. Preliminary characterization of this enzyme is reported in this communication.

Catechols↗
PubMedDate not supplied

Zinc levels in women and newborns.

Zinc is an important trace element having a definitive role in the metabolism, growth and development and reproduction. During pregnancy the requirements for zinc increase. This study was designed to evaluate the zinc status of normal women, normal pregnant women and their newborn babies. Forty normal adult females, 40 normal pregnant women and their newborn babies were randomly selected and their serum and hair zinc levels were analysed using atomic absorption spectrophotometer. The mean serum and hair zinc levels in normal women were 69.47 +/- 1.4 micrograms/dl and 147.45 +/- 6.12 micrograms/g respectively. The mean serum and hair zinc levels in normal pregnant women were 69.0 +/- 3.22 micrograms/dl and 142.83 +/- 4.39 micrograms/g respectively while the mean serum (cord blood) and hair levels in normal new born babies were 72.77 +/- 5.14 micrograms/dl and 188.36 +/- 4.12 micrograms/g respectively. There was a significant (p < 0.001) decrease in hair zinc levels during pregnancy. There was a significant (p < 0.05) decrease in zinc levels in new born babies when the time interval between the previous delivery and the present delivery was less than 3.4 years. The results of the present study reinforce the need for zinc supplementation during pregnancy especially if the interval between pregnancies is short.

Adult↗
PubMedDate not supplied

Dilated cardiomyopathy in non-specific aortoarteritis.

Out of 195 cases of Takayasu's arteritis who presented in our institute between January 1988 and December 1997, 12 (5.58%) had dilated cardiomyopathy. Age of these patients ranged from 10 to 30 years (17.25 +/- 5.30 years) and male-female ratio was 1:11. All the cases had cardiovascular system features (dyspnoea, oedema, palpitation, angina, etc. but without hypertension), three had central nervous system features (headache, vomiting, convulsion etc.) and all had general systemic features like weight loss, malaise, fever, arthralgia etc. Electrocardiography, chest X-ray and echocardiographic findings were consistent with dilated cardiomyopathy. Haemodynamic findings showed raised left ventricular end-diastolic pressure and pulmonary capillary wedge pressure in all; raised pulmonary artery pressure, pulmonary vascular resistance, right ventricular pressure and right atrial pressure in 6, 6, 4 and 2 cases, respectively; reduced left ventricular peak systolic pressure in 10 cases but central aortic pressure and systemic vascular resistance in all the cases were within normal limits. Angiography showed type I, II and III involvement in 7 (majority), 3 and 2 cases, respectively. Coronary and pulmonary angiography were normal and left ventricular angiography showed poor left ventricular systolic function in all the cases. Histopathological study (on 3 autopsy cases) showed non-specific inflammation of myocardium with lymphocyte/mononuclear cell infiltration and normal coronary vessels. So, dilated cardiomyopathy in Takayasu's arteritis is not rare, though not much reported, and can influence the prognosis of aortoarteritis cases.

Adolescent↗
PubMedDate not supplied

Experience with balloon valvuloplasty in pulmonary stenosis.

Fourteen patients of pure valvular pulmonary stenosis of moderate to severe degree underwent balloon valvuloplasty in the Department of Cardiology, SSKM Hospital, Calcutta. Haemodynamic study revealed that immediately after valvuloplasty, right ventricular pressure dropped down from 125 +/- 17.18 mmHg. to 56.67 +/- 8.72 mmHg. (mean +/- SD). Restudy was done in each case after 4 weeks, which showed that right ventricular systolic pressure had further dropped down to 46.71 +/- 5.06 mmHg. (Mean +/- SD). Patients were further followed up for 6 to 15 months (mean 10 months). During the follow-up period, all the patients remained asymptomatic. Drop of right ventricular systolic pressure was maintained except in one case in which the peak systolic pressure gradient across the pulmonary valve was raised to 61 mmHg. from 24 mmHg., the gradient achieved immediately after valvuloplasty.

Adolescent↗
PubMedDate not supplied

Pacing in children and adolescents.

Sixty patients aged 5-16 years underwent implantation of permanent pacemaker and were followed up for 3-11 years. All these patients presented with syncope or symptomatic bradyarrhythmias; two also had congestive cardiac failure in addition, which was ameliorated by pacemaker implantation. A majority of the patients (48) had congenital complete heart block. 8 patients presented with sick sinus syndrome; 4 patients presented with post operative chronic complete heart block. Transvenous endocardial electrode was used in 54 cases and epicardial pacing was done in 6 cases. A majority (55) of the patients received VVI pacemakers; AV sequential pacemakers were implanted in 5 cases. On follow up, the children returned to normal activity and their psychological well being was striking. Reoperation had to be done in 35 cases, a majority being due to over stretching of electrodes (15) and battery exhaustion (12). Two patients died, one due to bacterial endocarditis and the other succumbed to sudden death during vigorous physical activity. Major problems of pacing in children are that veins are often too thin and delicate for electrode insertion, and of the child's growth that stretches the lead system. The problems of pulse generator size and longevity have been partly overcome by introduction of newer models that are small and programmable.

Adolescent↗
PubMedDate not supplied

Coexisting polyostotic fibrous dysplasia and Paget's disease.

The following case report describes a patient who is known to have both fibrous dysplasia and Paget's disease, and traces his history over more than 50 years. The similarities and differences between the two conditions and their relative importance at the various stages of the history are discussed.

Aged↗
PubMedDate not supplied

Hypertension in the young in eastern India.

Three hundred and forty-one young hypertensives in the age group of 18-30 years were evaluated over a 7-year period. Essential hypertension constituted the single largest group (35.8%). Renal pathology was the most common cause of secondary hypertension (26.4%). Congenital coarctation of the aorta and endocrine causes accounted for 14.1 percent and 3.2 percent cases of secondary hypertension, respectively. A strikingly high incidence of nonspecific aortoarteritis (20.1%) was a distinguishing feature amongst secondary causes. Aortoarteritis was the commonest cause of renal artery stenosis. Renal angioplasty was performed in 11 patients with refractory hypertension. Forty percent of the patients achieved post-angioplasty control of blood pressure without drugs; in 25 percent, the blood pressure became easier to control. Restenosis was detected in 4 cases over 18-24 months of follow-up.

Adolescent↗