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Biomedical subjects

A K Samanta

Publications and source records attributed to A K Samanta.

At least 37 records · Page 2Linked to original sources
PubMed1989

Identification and characterization of specific receptors for monocyte-derived neutrophil chemotactic factor (MDNCF) on human neutrophils.

Specific receptors for a recently purified and cloned monocyte-derived neutrophil chemotactic factor (MDNCF) have been identified on the surface of normal human peripheral blood neutrophils using 125I-labeled recombinant human MDNCF (125I-MDNCF). Competitive binding of 125I-MDNCF to human neutrophils reached a maximal level at 1-3 h at 4 degrees C. The Scatchard analysis showed that there are approximately 20,000 receptors per cell with a single type of high affinity binding (Kd, 8 x 10(-10) M). The receptors for MDNCF are clearly distinct from the receptors for other cytokines and chemotactic agents, e.g., IL-1 alpha, TNF-alpha, and FMLP, C5a, leukotriene B4, and platelet activating factor. Based on the SDS-PAGE analysis of chemically crosslinked 125I-MDNCF receptor complex, there are two polypeptides that bind MDNCF; the molecular weight of these two MDNCF receptors were estimated to be 67,000 and 59,000. Treatment of a promyelocytic cell line, HL60, with 1.25% DMSO for 5 d in vitro increased the number of receptors up to 7,000 receptors/cell with a Kd of 1.2 x 10(-9) M.

Chemotactic Factors↗
PubMed1989

Effect of peritoneo-venous shunt on portal pressure.

The cause of variceal bleed after a peritoneo-venous shunt is not known. Portal haemodynamic consequences of a peritoneo-venous shunt are poorly understood. The most critical period after a peritoneo-venous shunt is the early postoperative period when rapid mobilisation of peritoneal fluid occurs. Serial changes in the portal pressure during the early postoperative period have not been recorded. In the present study preoperative wedge hepatic vein (WHV), right atrial (RA) and pulmonary capillary wedged (PCW) pressures, cardiac index (CI), and plasma volume (PV) were measured in five alcoholic cirrhotic patients with tense ascites for up to 20 hours postoperatively. The longterm effect was assessed by repeating the intrahepatic and/or wedged hepatic vein pressures in three of the surviving patients after 10 to 20 months. A significant increase in the circulatory dynamics and portal pressure was seen within two hours after shunt placement. Wedged hepatic vein pressure increased from 27.6 (8.2) mmHg to 37.2 (9.2) mmHg (p less than 0.01), RA pressure increased from 6.8 (1.5) mmHg to 14.0 (4.3) mmHg (p less than 0.05), PCW increased from 7.2 (3.5) mmHg to 19.3 (5.7) mmHg (p less than 0.01), CI increased from 3.4 (0.27) lit/m2/min to 4.3 (0.85) lit/m2/min (p less than 0.05). This was accompanied by a 34% increase in the plasma volume from 1838.5 (142.1) to 2471.4 (210) ml/m2. These derangements were maintained up to 20 hours postoperatively. After 10 to 20 months, repeat measurements revealed a return to preoperative measurements. It is concluded that there is an acute increase portal pressure after a peritoneo-venous shunt attributed to increased circulation plasma volume, resulting from rapid mobilisation of ascitic fluid after the shunt. A sudden increase in portal pressure might be an important provoking factor for variceal bleeding after peritoneo-venus shunt.

Blood Pressure↗
PubMed1985

Adhesion-related colonic varices.

Most colonic varices are attributable to portal hypertension. Intra-abdominal adhesions have been incriminated as the cause of intestinal varices only in association with portal hypertension. We present the first well-documented occurrence of adhesion-related colonic varices in the absence of portal hypertension or other known associated conditions. It is important to delineate the mesenteric vascular anatomy in order to select the appropriate surgical procedure.

Colon↗
PubMed1984

Mycoversilin, a new antifungal antibiotic. I. Fermentation, isolation and biological properties.

A new antifungal antibiotic, mycoversilin, was isolated from the culture filtrate of Aspergillus versicolor (N5)17 by repeated column chromatography and recrystallized from ethyl acetate as homogeneous fine needles. Maximum production took place in a medium containing 4% glucose and 1% peptone at pH 3.5, temperature 28 degrees C after 8-9 days of incubation under stationary condition. Mycoversilin is a narrow spectrum antibiotic with activity against filamentous fungi, particularly Trichophyton rubrum (MIC 15 micrograms/ml).

Antifungal Agents↗
PubMed1984

Mycoversilin, a new antifungal antibiotic. II. Structure elucidation.

The structure of a new antifungal antibiotic, mycoversilin, produced by Aspergillus versicolor (N5)17 was determined as I by various spectroscopic and chemical methods. Mycoversilin is a unique polynuclear aromatic compound having two methyl and six hydroxyl groups and two ether linkages. The acetyl derivative prepared was found to have no antifungal property.

Antifungal Agents↗
PubMed1983

Characterization of pyridine nucleotide binding site of UDP-glucose 4-epimerase from Saccharomyces fragilis.

UDP-glucose 4-epimerase from Saccharomyces fragilis has 1 mol of NAD firmly bound per mol of the dimeric apoenzyme. This prevents a direct study of the coenzyme binding site of the protein. Dissociation of the dimer with p-chloromercuribenzoate and its reconstitution with exogenous NAD or one of its analogues and 2-mercaptoethanol provides an indirect method of study of the site. Depending on the reconstitution properties, the analogues can be classified in the following groups: (i) analogues that have no affinity for the site; (ii) analogues that have affinity but are not incorporated into the apoenzyme; (iii) analogues that produce catalytically inactive holoenzymes; and (iv) analogues that produce catalytically active holoenzymes. Minimum structural requirements that lead to affinity for the coenzyme site and to binding to the apoenzyme can also be discerned from these studies. Reconstitution with etheno-NAD, a fluorescent analogue of NAD, indicates the presence of a hydrophobic pocket for the adenosine subsite.

Binding Sites↗
PubMed1982

The presence of elements of a dinucleotide fold in UDP-glucose 4-epimerase from Saccharomyces fragilis.

UDPglucose 4-epimerase (EC 5.1.3.2) from Saccharomyces fragilis is a holoenzyme containing 1 mol NAD per mol dimeric protein. The enzyme can be dissociated with p-chloromercuribenzoate and can be reconstituted in the presence of 2-mercaptoethanol and exogenous NAD. Using Cibacron blue F3GA in this reconstituting system, competition between NAD and the dye for the pyridine nucleotide-binding site could be demonstrated. Inactive holoenzyme containing Cibacron blue can also be obtained under these conditions. These data suggest the possible presence of elements of a dinucleotide fold in this enzyme.

Anthracenes↗
PubMed1982

Molecular connectivity and antifungal activity. A quantitative structure-activity relationship study of substituted phenols against skin pathogens.

The plot of minimum inhibitory concentration (MIC) vs. 2Xv of twelve phenolic compounds delineates the congeners into three distinct classes: the most potent ortho compounds describe a parabola, para substituted compounds of intermediate potency lie in a line, while the least potent meta derivatives yield a scatter diagram. The same pattern is found for two skin pathogens, Trichophyton rubrum and Epidermophyton floccosum. From non-linear regression analysis 2Xv is found to be excellently correlated with observed MIC values of the most potent ortho compounds against both the test organisms. For both the organisms logP is found to be inferior to 2Xv in the correlation of MIC values. On the basis of regression equations the MIC values of certain ortho substituted phenols are calculated a priori, some of which are corroborated by findings reported in the literature.

Antifungal Agents↗
PubMed1980

Role of porta systemic shunt and hepatocellular damage in the genesis of hepatic neuropathy.

A study was undertaken to evaluate the relative role of porta-systemic shunts and hepatocellular damage in the genesis of neuropathy in chronic liver disease. Two of the 14 patients with non-alcoholic cirrhosis showed clinical evidence of neuropathy, whereas none of the patients with idiopathic portal fibrosis had evidence of neuropathy clinically. Decreased motor conduction velocities were present in some cases of idiopathic portal fibrosis as well as non-alcoholic cirrhosis. Subclinical evidence of histopathological neuropathy in the form of segmental demyelination and remyelination as well as myelin fiber loss was seen in 10 out of 11 sural nerves studied in idiopathic portal fibrosis group and in all the 10 patients in the non-alcoholic cirrhosis group. No correlation was found between histological features and various parameters studied. It is postulated that the development of clinical or subclinical neuropathy in chronic liver disease depends on two factors, being collateral shunting and hepatocellular damage or both and probably related to abnormalities of nitrogen metabolism.

Adult↗
PubMed1978

Diagnostic value of combined transhepatic venography and inferior vena cavography in chronic Budd-Chiari syndrome.

In a series of 19 patients with Budd-Chiari syndrome, transhepatic venography and inferior vena cavography were used to localize the site of hepatic outflow obstruction. Classification into two types was made on the basis of the site of obstruction. Four cases were grouped as type I, in which obstruction was localized in the hepatic vein alone, and the inferior vena cava (IVC) was patent. Fifteen cases were of type II, in which there was a well-defined obstruction in the intrahepatic portion of the IVC or ostium of a hepatic vein. This study highlights the frequent occurrence of IVC obstruction as a cause of chronic Budd-Chiari syndrome in northern India and the utility of transhepatic venography in its diagnosis.

Adolescent↗