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Biomedical subjects

G Abraham

Publications and source records attributed to G Abraham.

At least 163 records · Page 9Linked to original sources
PubMed1975

The 5' terminal structure of the methylated mRNA synthesized in vitro by vesicular stomatitis virus.

The 5' terminal structure of the mRNA synthesized in vitro by the virion-associated RNA polymerase of vesicular stomatitis virus in the presence of S-adenosyl-L-methione consists of 7-methyl guanosine linked to 2'-O-methyl adenosine through a 5'-5' pyrophosphate bond as m7G(5')ppp(5')A-m-p ... The alpha and beta phosphated of GTP and alpha phosphate of ATP are incorporated into the blocked 5' terminal structure.

Adenosine↗
PubMed1975

Methylated and blocked 5' termini in vesicular stomatitis virus in vivo mRNAs.

Methyl groups derived from 3H-methyl methionine were incorporated into vesicular stomatitis virus (VSV) MRNAs isolated from infected cells. Sequential degradation of the 12-18S viral mRNA species with ribonuclease T2, penicillium nuclease, and alkaline phosphatase yielded a single 3H-labeled dinucleotide. A similar resistant 32P-labeled fragment was obtained by digesting VSV mRNA uniformly labeled with 32P. This methylated and blocked oligomer was further cleaved with nucleotide pyrophosphatase, yielding two methylated 5' nucleotides. We postulate that the 5' terminal structure of the vivo 12-18S VSV mRNA contains 7-methylguanosine linked by a 5'-5' pyrophosphate bond to a methylated derivative of adenosine. In contrast to the mRNAs (+ strand), the VSV genome RNA ( MINUS STRAND) IS NOT BLOCKED.

Adenosine↗
PubMed1975

Poliovirus polypeptides examined in more detail.

The pattern of viral polypeptide synthesis and cleavage in poliovirus-infected cells was shown by autoradiography to be considerably more complex than previously thought. In normal growth, at least 26 distinct polypeptides were found, and various modifications of the cleavage process revealed a total of at least 34. Most of the new polypeptides were minor components that were unstable during a chase. Different cultural modifications led to different polypeptide ratios, and it appeared likely that several cleavage activities were involved . Minor differences were found in the polypeptide contents of cytoplasmic extracts and whole infected cells. The complexity of the cleavage pattern necessitated a new nomenclature based on mol. wt. (e.g. Pp110, "poliovirus protein" of 110000). Particular attention was paid to mol. wt. determinations, notably in the use of internal protein standards and more fully denaturing gel conditions. The size of the "primary translation product" of poliovirus RNA was found to be 210000 daltons, so that either 20% of the viral genome is not translated in vivo, or some is read as a smaller independent translation unit.

Cell Line↗
PubMed1975

Relations between poliovirus polypeptides as shown by tryptic peptide analysis.

Poliovirus proteins were labelled in vivo with [35S]-methionine, and the major products of translation and cleavage were separated by electrophoresis and compared in terms of two-dimensional tryptic peptide maps visualized by autoradiography. The main intermediates p110 and p90 had few or no methionine-labelled sequences in common, but were both contained in, and therefore almost fully account for, the presumed primary translation product p210. The sequences of p79, a major stable product of cleavage and a non-structural protein, were almost completely contained in p90, which in turn is the major component of the larger intermediates p168 and p155. P110 is confirmed as the precursor of virus particle protein, and VP0 as the precursor of VP2. However, the sequences of p31, the other major product of translation that is not a stuctural protein, were not contained in any of the viral polypeptides mentioned above.

Autoradiography↗
PubMed1974

The roles of IgG, IgM rheumatoid factor, and their complexes in the induction of polymorphonuclear leukocyte chemotactic factor from complement.

The induction of chemotactic factor by rheumatoid factor (RF) and by rheumatoid complexes and their constituents was investigated. The presence of chemotactic factor was measured by the number of polymorphonuclear leukocytes (obtained from normal individuals) attracted through a 3 mum Millipore filter and is expressed as a "chemotactic index." The chemotactic index was used to measure the effect of immunoglobulins and their complexes in stimulating production of complement-derived chemotactic factors from the sera of normal individuals. Two sources of IgG (F-II and DEAE-purified IgG) were used. These were prepared for use in the native and heat-aggregated states. The same chemotactic index was obtained with both these preparations of IgG. The chemotactic index increases when (a) increasing concentrations of gamma globulin were added to a constant concentration of complement and (b) when the amount of complement alone was increased. The addition of a purified IgM RF to the mixture of IgG and complement caused a decrease in the chemotactic index. Incubation of IgG and complement before addition of IgM RF produced no change in the chemotactic index. The addition of a nonrheumatoid factor IgM to IgM and complement had no effect on the chemotactic index. IgM RF and IgG alone were not chemotactic. These studies confirm the concept of "complement deviation" by IgM RF which occurs with, and as a result of, the immune complex formation between IgG and IgM RF. The successful activation of complement chemotactic factors by IgG may explain the synovitis with high polymorphonuclear leukocyte counts found in RF-negative arthritis.

Antigen-Antibody Complex↗
PubMed1973

The relationship between L-chain synthesis and gamma-globulin production.

The simultaneous administration of labeled human gammaG globulin and L-chains to subjects has allowed examination of the metabolic relationship between a component part and the whole immunoglobulin molecule. Studies were carried out in a series of control subjects and in a group of patients where substandard production of gamma-globulin was anticipated, i.e., patients with the nephrotic syndrome on chronic Imuran therapy and patients with uremia. Full expression of the plasma decay curve was obtained for both substances, that for L-chain requiring only 4-5 days except in uremic subjects and that for gamma-globulin requiring up to 30-40 days. Urinary excretion of inorganic iodide was also quantitated for 20-30 days. Equilibrium of the extravascular, vascular, and urinary radioactivity from the labeled gammaG globulin was usually not seen during this time interval suggesting more than one site of catabolism of the protein. Excess L-chain poduction was about 45% of the total L-chain production and probably in no instance could account for the low gamma-globulin production seen in certain patients with renal disease.

Adult↗