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Biomedical subjects

S N Banerjee

Publications and source records attributed to S N Banerjee.

68 records · Page 4Linked to original sources
PubMed1979

Aminonitriles and aminothioamides related to natural amino acids.

N-p-Methoxybenzyloxycarbonyl and N-tert.-butyloxycarbonyl amino acid amides related to a series of natural amino acids were dehydrated to the corresponding Meoz- and Boc-alpha-aminonitriles. Deprotection of the latter derivatives afforded alpha-aminonitriles related to alanine, tyrosine, phenylalanine, dihydrophenylalanine, histidine, Dopa, ornithine, asparagine and glutamine. Thioamidation with H2S/NH3 or H2S/NEt3 in general converted the protected amino nitriles to Meoz- and Boc-alpha-aminothioamides. When deprotected these furnished the alpha-aminothioamides corresponding to alanine, tyrosine, phenylalanine, dihydrophenylalanine and histidine. For dehydration and thioamidation of histidine and Dopa, N alpha-Boc-im trityl-histidine and N-Boc-O, O'-diacetyldihydroxyphenylalanine were useful. Dopa was obtained as the free and Boc-thiohydrazide. Also prepared were N alpha,omega-diMeoz-ornithine DCHA, Meoz-2,5-dihydrophenylalanine DCHA and N,O-diMeoz-tyrosine as starting materials and N,O-dicarbobenzyloxycarbonyltyrosinamide, N,O-diZ-tyrosine nitrile and Z-beta-cyano-beta-alaninamide as model compounds. During deprotection of Meoz-alanine thioamide, transfer of an anisyl group from the N-Meoz protecting group to sulfur took place as a side reaction that yielded alanine p-methoxybenzyl beta-imidothiolic ester. This study provides two new series of amino acid analogs with potential antimetabolite activity. Also suitable for incorporation into peptide analogs, these afford approaches to relating structure and conformation to activity in biologically active peptides.

Amides↗
PubMed1976

Inhibition of Pichinde virus replication by actinomycin D.

The yields of Pichinde virus, a member of the arenavirus group, were markedly inhibited when infected BHK 21 cells were incubated in the presence of 0.4 to 4 mug/ml of actinomycin D. Maximal inhibition was observed when actinomycin D was added after the adsorption of virus to cultures; however, addition of drug as late as 12 h after infection reduced the 24 h yield by 50%. Virus antigen synthesis, as measured by complement fixation and immunodiffusion, was not dramatically reduced by actinomycin D. The expression of virus antigens on the surface of infected cells was greater on cells treated with actinomycin D than on untreated cells. Putative defective particles with a density of Pichinde virus were not detected in fluids of cultures incubated with actinomycin D and 3H-amino acids. Actinomycin D appears to inhibit Pichinde virus late in the replicative cycle. The observations raise the possibility that the drug inhibits the synthesis of proteins of the host cell membrane which are required for virus maturation.

Antigens, Viral↗
PubMedDate not supplied

One program's experience of OSCE vs. written board certification results: a pilot study.

The objective structured clinical examination (OSCE) has been the focus of a lot debate with respect to reliability and validity. Much of the controversy surrounding these components lies in a lack of comparison with a "gold standard." Further work is needed to improve the evaluation of clinical skills to the point that a gold standard can truly be said to exist.

Certification↗
PubMedDate not supplied

An evaluation of oligoclonal banding and CSF IgG index in the diagnosis of neurosyphilis.

It can be difficult to determine which patients would benefit from therapy to control central nervous system infection with Treponema pallidum. The authors have followed patients prospectively to evaluate two new diagnostic tests available. They performed lumbar punctures on 107 consecutive patients with syphilis of unknown duration, untreated (n = 19) or with serology that did not decrease sufficiently during follow-up (n = 88). The mean age was 47 years, with 91 males and 16 females. Twelve had neurologic symptoms. In order to establish a gold standard, the authors required the cerebrospinal fluid Venereal Disease Research Laboratory (CSF VDRL) test to be reactive (n = 25). They then examined oligoclonal banding and CSF IgG index as diagnostic tests by comparing them to the gold standard. Oligoclonal banding, abnormal in 20, had a sensitivity of 52% and a specificity of 91%. The CSF IgG index, abnormal in 56, had a sensitivity of 92% and a specificity of 60%. The posttest likelihoods of a positive test result were low, and hence neither test ruled in the diagnosis. With a post-test likelihood (PTL) negative of 4%, a negative CSF IgG index assisted in ruling out the diagnosis. Oligoclonal banding was not a satisfactory test for neurosyphilis. The CSF IgG index appears to help only in ruling out infection. Further effort is needed in developing diagnostic tests to assist the clinician in the diagnosis of neurosyphilis.

Electrophoresis, Agar Gel↗
PubMedDate not supplied

Requirement of cell nucleus for the replication of an arenavirus.

Baby hamster kidney (BHK21) cells enucleated with cytochalasin B were infected with Pichinde virus or Sindbis virus. Viral replication was measured by plaque assay, and the synthesis of viral antigens was determined by immunofluorescence. Pichinde virus replication was completely inhibited in cells enucleated prior to infection as measured by both techniques while the replication of Sindbis virus was unaffected. Enucleation of cells at different times after infection with Pichinde virus indicated that intact nuclei were required for at least 8 h after infection.

Antigens, Viral↗
PubMedDate not supplied

Differential clastogenic sensitivity of heterochromatin and euchromatin: evidence from an in vivo study made on a submammalian vertebrate.

One of the properties often attributed to heterochromatin is its susceptibility to induced aberrations and exchanges. However, earlier studies made mostly on different mammalian in vitro cell lines on the distribution of aberrations within euchromatin and heterochromatin at metaphase chromosome level have given contradictory results. In the present study, an attempt has been made to evaluate the clastogenic sensitivity of heterochromatin and euchromatin using somatic chromosome complements of a submammalian vertebrate as experimental model and considering both chromosome aberrations and SCEs as end points.

Animals↗