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Biomedical subjects

R Banerjee

Publications and source records attributed to R Banerjee.

At least 217 records · Page 12Linked to original sources
PubMed1976

Non-equivalence of human hemoglobin chains in the oxidation-reduction and heme-transfer reactions. A 13C nuclear-Magnetic-resonance study.

12C nuclear magnetic resonance (NMR) spectroscopy has been applied to the investigation of chain non-equivalence for two reactions of human hemoglobin: oxidation-reduction and hemetransfer. The method is based on previous observations that in the carbonyl region, Hb13CO gives two well-resolved resonances which arise from 13C of carbonyls bound respectively to the alpha and beta chains; moreover, integration of spectra allows on e to estimate their relative abundance. A mixture of ferrous and ferric hemoglobins in dye-mediated oxidation-reduction equilibrium can be formally considered to be equivalent to two redox couples in equilibrium, namely alphaIII/alphaII and betaIII/betaII; from a knowledge of these ratios, one can conclude whether the chains are equivalent or not in their oxidation-reduction properties. In this work, these ratios were evaluated by reacting the redox systems with 13CO and integrating the 13C NMR spectra. The results show differences in the intrinsic oxidation-reduction potentials of the chains in hemoglobin tetramer, E1/2(beta)being higher than E1/2(alpha)in neutral solution but not at pH9 and above. The binding of inositol hexakisphosphate does not modify the difference between beta and alpha though substantially increasing the overall potential The results are discussed in the light of current hypotheses to account for the change of Hill coefficient with pH for the reaction studied. The non-equivalence of chains is shown also for heme transfer from methemoglobin. For the phosphate-free protein, the beta chains lose heme more rapidly than that alpha chains; the addition of inositol hexakisphosphate results in the decrease of overall heme transfer as well as of chain heterogeneity.

Binding Sites↗
PubMed1976

Comparative ultrastructure of thyroid, tongue and eyelid lesions in the neuroma phenotype of medullary carcinoma of the thyroid: association of amyloid with fibroblasts in thyroid tumor and in mucosal neuromas.

Electron-microscopic and histochemical studies of thyroid tumor, tongue neuromas and eyelid neuromas from the lesions of a patient with medullary thyroid carcinoma were compared. In the thyroid tumor, a significant number of the C cells showed heterogeneity of granule types; no C cells, however, were identified in the tongue and eyelid neuromas. Amyloid was clearly shown by Congo red staining in the thyroid neoplasm and in the tongue neuromas. In all tissues, amyloid fibrils were found to be ultrastructurally closely associated with fibroblasts. These fingings suggest that the fibroblast rather than the C cell may have played the important role in the deposition of amyloid in this patient's thyroid carcinoma.

Amyloid↗
PubMed1976

Structure-volume relationships in hemoglobin. A densitometric and dilatometric study of the oxy leads to deoxy transformation.

Partial volume measurements have been performed for human hemoglobin, both on the oxygenated and deoxygenated forms. Density measurements (by pycnometry) give vHbO2 = 0.752 +/- 0.002 and vHb =0.753 +/- 0.006 for the partial specific volume and do not distinguish between the two different structures. Differential measurements, by dilatometry, however, show a signigicantly higher molal volume (of about 50 cm3/mol hemoglobin tetramer) for the deoxy over the oxygenated from at pH 7. The same reaction, at pH 9, gives a much smaller increase or even a decrease of volume. The different volume changes at pH 7 and at pH 9 are not due to the so-called Bohr ionization but to the weakening, at pH 9 compared to pH 7, of stabilising salt linkages in the deoxy structure.

Hemoglobins↗
PubMed1976

Lung involvement in angioimmunoblastic lymphadenopathy (ail).

Two patients with angioimmunoblastic lymphadenopathy (AIL) in whom the disease process involved the lungs are reported. One patient died in respiratory failure. Details of the radiologic appearance, abnormalities of lung function and lung histology are presented together with response to steroid therapy in one patient. Life-threatening involvement of the lung parenchyma can be a mode of presentation of the disease and can contribute to the morbidity and mortality of the disorder.

Aged↗
PubMed1975

Magnetic susceptibility measurements of deoxygenated hemoglobins and isolated chains.

Static magnetic susceptibility measurements have been performed in a wide temperature range (4.5-300 degrees K) on ligquid/frozen solutions of deoxygenated human hemoglobin and its isolated chains. The effects of buffer, pH, dielectric constant and phosphate have been investigated. Measurements have been done also on human fetal chains, on des-Arg and SucNEt-des-Arg hemoglobins. In all the proteins under study of the Fe2+ is the high spin state (S=2). At room temperature the magnetic moments lie in range 4.90 (theoretical spin-only value) to 5.45 Bohr magnetons. Local differences between the iron sites are revealed by the low temperature measurements. A mechanism is proposed to explain the effect of phosphate binding on the magnetic susceptibility.

Adult↗
PubMed1975

Recombination of carbon monoxide with hemoglobin after flash photolysis of the carboxyderivative in mixed solvents at subzero temperature.

The kinetics of recombination of carbon monoxide to hemoglobin produced by total flash photolysis of its carboxyderivative are studied at low temperatures (down to --55 degrees C) in mixed hydroalcoholic solvents. The rates are found to be different in two solvents used, namely ethylene glycol/buffer and methanol/buffer; for the former, the rates at subzero temperatures are simply explained by cooling and are consistent with the activation energy as measured in aqueous solution, while those in methanol/buffer show evidence of a specific solvent effect. Values are reported for the rate constants and activation energies in the two solvents.

Carbon Monoxide↗
PubMed1975

Heme reactivity of hemoglobins. Azide and fluoride binding equilibria of free and mercuriated ferri-gamma chains.

The free gamma chains, isolated from human foetal hemoglobin, are stable when oxidized and thus suitable for ligand binding and subunit equilibrium studies. The metaquo-ferri chains, with cysteine-F9 in the free state II ag gamma SH) possess several properties which are different from those of their p-mercuribenzoate derivative (III aq gammaSHgR); these are: stronger binding of a high-field ligand (N3- minus), altered spin equilibrium and an altered subunit equilibrium. A quantitative assessment of the free energy changes associated with all individual steps involved in changing the metaquo chains to their azide derivatives has been made. The results show that the higher apparent reactivity of III ag gammaSH (compared to IIIaq gammaSHgR) for the azide ion is not solely due to compensatory effects arising from differences of subunit dissociation or of spin equilibrium: other process(es) occurring in the ligand binding site have to be considered.

Azides↗
PubMed1974

The kinetics of conformational changes in hemoglobin, studied by laser photolysis.

Photolysis of carbon monoxide and oxygen derivatives of hemoglobin by a short laser pulse produces a transient species that rapidly decays to normal deoxyhemoglobin. The effect, which is also observed on single chain proteins and on noncooperative aggregated forms, has been interpreted as corresponding to structural changes in the heme pocket on ligand dissociation. The decay of the transient species follows first-order kinetics with constants ranging from 0.8 to 1.8 x 10(7) sec(-1). In cooperative hemoglobins, the kinetic constants are pH-dependent, though remaining first- or pseudo first-order at all wavelengths. This shows the close linkage of tertiary and quaternary structure changes in normal hemoglobin.

Animals↗
PubMed1974

The relationship between urinary infection, cystoscopic appearance, and pathology of the bladder in man.

Studies of bladder histology were made in patients with recurrent urinary infection or symptoms of cystitis, with a view to establishing its relationship to symptoms, cystoscopic appearance, and bacilluria. Bladder biopsies were taken from the patients and compared with control material obtained at necropsy. Acute inflammatory changes were inconstant and sometimes sparse. Chronic inflammatory changes were often marked, and were ranked by severity into four grades. There was a statistically significant correlation between the more severe grades and the finding of bacilluria, which was not dependent on sex or age. The grades in patients with recurrent non-bacterial dysuria (;urethritis') lay between those of the controls and the infected patients, and were statistically different from both. There was no correlation between these grades and either symptoms or the finding of trigonal hyperaemia during cystoscopy. However, heavy lymphocytic infiltration, and particularly germinal follicle formation, frequently resulted in macroscopic tubercle-like nodules which were visible on cystoscopy. Such germinal follicles may contribute to local antibacterial defences by their production of immunoglobulins, and may explain the high antibacterial antibody titres sometimes found in the sera of subjects with infection confined to the lower urinary tract.

Adult↗