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Biomedical subjects

M Jacob

Publications and source records attributed to M Jacob.

At least 343 records · Page 19Linked to original sources
PubMed1966

Comparison of two serologically distinct ribonucleic acid bacteriophages. I. Properties of the viral particles.

Overby, L. R. (University of Illinois, Urbana), G. H. Barlow, R. H. Doi, Monique Jacob, and S. Spiegelman. Comparison of two serologically distinct ribonucleic acid bacteriophages. I. Properties of the viral particle. J. Bacteriol. 91:442-448. 1966.-Two ribonucleic acid (RNA) coliphages, MS-2 and Qbeta, have been characterized physically and serologically. MS-2 has an S(20, w) value of 79, a molecular weight of 3.6 x 10(6), a density of 1.422, and pH 3.9 as its isoelectric point. Qbeta has an S(20, w) of 84, a molecular weight of 4.2 x 10(6), a density of 1.439, and an isoelectric point at pH 5.3. One host (Escherichia coli A-19) permits a distinction between the two on the basis of a marked difference in plaque size. They are distinct immunochemically, no serological cross-reaction being detectable.

Centrifugation↗
PubMed1966

Comparison of two serologically distinct ribonucleic acid bacteriophages. II. Properties of the nucleic acids and coat proteins.

Overby, L. R. (University of Illinois, Urbana), G. H. Barlow, R. H. Doi, Monique Jacob, and S. Spiegelman. Comparison of two serologically distinct ribonucleic acid bacteriophages. II. Properties of the nucleic acids and coat proteins. J. Bacteriol. 92:739-745. 1966.-The ribonucleic acid (RNA) molecules and coat proteins of two RNA coliphages, MS-2 and Qbeta, have been characterized. MS-2 RNA shows an S(20,w) of 25.8 and a molecular weight by light scattering of 10(6). The corresponding parameters for Qbeta-RNA were 28.9 and 0.9 x 10(6). A difference in base composition was reflected in the adenine-uracil ratio, which was 0.95 for MS-2 and 0.75 for Qbeta. The two RNA preparations are readily separated by chromatography on columns of methylated albumin. Both gave identical bouyant densities in cesium sulfate of 1.64 g/ml. The coat protein subunits were of similar molecular weights: 15,500 (Qbeta) and 14,000 (MS-2). They differed, however, in that the Qbeta-protein lacked tryptophan and histidine, whereas the MS-2 protein lacked only histidine.

Adenine↗
PubMedDate not supplied

A novel RNA from early region 3 of adenovirus-2.

A novel RNA species was detected by Northern blotting among the polyadenylated nuclear transcripts from early region 3 of adenovirus-2. Preliminary mapping showed that it encompasses the E3 leader 1 and part of IVS 1. Primer extension experiments revealed that its 5' end (C) was the same as that of all E3 transcripts, and S1 nuclease mapping showed that its 3' end was a polyadenylation site (P1) known to be used in the late phase of infection. The body of this RNA is 618-619 nucleotides long and we propose to name it E3-CP1. Kinetic studies suggest that it is a primary transcript as are the E3 premessenger RNAs.

Adenoviruses, Human↗
PubMedDate not supplied

Spray-dried microparticulate systems containing acetaminophen.

The present work investigates the preparation and the release of acetaminophen from spray-dried microparticles. Two cellulose derivatives were tested as sustaining agents: microcrystalline cellulose (MCC) and sodium carboxymethylcellulose (NaCMC). In-vitro dissolution studies were carried out in dissolution media of different pH. With MCC, the adsorption of acetaminophen on the surface or in the pores of the polymer does not allow a significant sustained release of the drug, which completely dissolves in 1 h. Conversely, the use of NaCMC retards the release of acetaminophen over a period of 6-8 h. The drug release depends on the plasticizer used and on the pH of the dissolution medium, and the mechanism consists essentially in the diffusion of the drug through the swollen polymeric matrix. The pH dependence observed can be correlated with a lower hydrophylicity of the polymer in acidic medium, which retards gel formation.

Acetaminophen↗
PubMedDate not supplied

Confirmation of 11-nor-delta 9-tetrahydrocannabinol in urine as its t-butyldimethylsilyl derivative using GC/MS.

A procedure for the detection and quantitation of 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid, the major metabolite of delta 9-tetrahydrocannabinol, in urine is presented. Because a significant portion of the metabolite is present as a conjugated form, the urine was hydrolyzed by the addition of strong base. The solution was then acidified and the metabolite extracted into an organic solvent. It was subsequently converted to the t-butyldimethylsilyl ether and t-butyldimethylsilyl ester, and analyzed by GC/MS utilizing electron ionization (EI). Confirmation of the product was carried out by using selected ion monitoring (SIM) for three ions which represent logical demonstrable fragmentation pathways for the molecule and by comparing their relative abundances to a reference standard. A deuterated analog was carried through the entire process as an internal standard. The method provides excellent linearity and the derivatives are stable for more than 10 days at room temperature.

Dronabinol↗
PubMedDate not supplied

Specific interactions of pancreatic amylase at acidic pH. Amylase and the major protein of the zymogen granule membrane (GP-2) bind to immobilized or polymerized amylase.

Regulated secretory proteins are thought to be sorted in the trans-Golgi network towards the secretory granule via acidic aggregation. In the exocrine pancreas, amylase is one of the major zymogens. It is a basic protein of pI 8.6 and does not precipitate in acidic conditions. To identify the mechanism by which amylase aggregates in the acidic cisternae of the pancreatic trans-Golgi network, we have developed an in vitro model in which amylase was fixed to plastic microtiter plates. The fixed amylase was probed with two ligands: amylase itself and GP-2, the major protein of the zymogen granule membrane. Biotinylated amylase bound to fixed amylase in a strict pH-dependent manner with optimal binding between pH 5.0 and 5.7. The affinity of binding was in the nanogram range (Kd approximately 20.0 ng/mL) at pH 5.5. Acid binding of amylase was not reversible by incubation at neutral pH, nor could it be displaced by native amylase. GP-2 binding to fixed amylase was also pH dependent with optimal binding between pH 5.0 and 5.7. As for amylase, it was not reversible by incubation at neutral pH. GP-2 binding sites on fixed amylase appeared to be different from those of biotinylated amylase. While native and biotinylated amylase did not bind to GP-2, polymerized amylase precipitated GP-2 at acidic pH. Taken together these data suggest that slight modifications are sufficient to reveal on the amylase molecule binding sites for GP-2 and for amylase itself. These new binding capacities acquired at acidic pH could be involved in the cascade of reactions that lead to the in vivo formation of the immature secretory granule.

Amylases↗