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Biomedical subjects

J B Johnson

Publications and source records attributed to J B Johnson.

At least 73 records · Page 4Linked to original sources
PubMed1976

Spectrophotometric determination of sodium nitroprusside and its photodegradation products.

A specific spectrophotometric method of analysis for sodium nitroprusside was developed utilizing the molar absorptivity values at the maxima appearing in the electronic spectrum at 394 and 498 nm that may be attributed to metal d leading to pi* NO transitions. These measurements appear to be indicative of the unaltered nitroferricyanide complex. A reaction sequence is postulated for aqueous solutions of nitroprusside exposed to normal artificial light. Evidence suggests that one species in the sequence is nitroferricyanide in a higher energy state but with the nitrosyl moiety still present in the coordination sphere, which exhibits an increased molar absorptivity at 394 nm. The molar absorptivity at the 498-nm maximum remains unchanged. Corroborating polarographic data are presented.

Chemical Phenomena↗
PubMed1976

Stability of vitamin C (ascorbic acid) in tablets.

Stability of ascorbic acid (vitamin C) in various tablet formulations and the nature and extent of formation of decomposition products (dehydroascorbic acid, diketogulonic acid, and oxalic acid) were determined under normal conditions of storage and in simulated use tests. IR spectrophotometric, colorimetric, fluorometric, titrimetric, polarographic, and chromatographic methods were applied. Recent implications concerning the instability of ascorbic acid in tablets and the potentially harmful nature of the breakdown products are shown to be unfounded. Under normal storage conditions, commerical-type ascorbic acid tablets are stable for over 5 years (greater than 95% potency retention). The amounts of all three breakdown products formed under the various storage conditions constitute a small percentage of the ascorbic acid content and pose no dietary hazard. IR spectroscopy was inadequate as a quantitative method for evaluating ascorbic acid potency in tablet formulations. The official titration methods and TLC, colorimetric, and polarographic determinations correlate well and define accurately the stability of ascorbic acid in these dosage forms.

Ascorbic Acid↗
PubMed1976

Safety of viral vaccine cell substrates: a reevaluation.

Primary cultures of African green monkey kidney and rabbit kidney as well as diploid cell lines WI-38 and DBS-FRhL-2 were examined for evidence of tumorigenicity and latent RNA tumor viruses. Cells inoculated into immunosuppressed newborn hamsters and rhesus monkeys were not tumorigenic. Cells treated with 2'-deoxy-5-iodouridine to induce the production of latent viruses were examined by electron microscopy, density gradient centrifugation, and the reverse transcriptase enzyme assay. No evidence was found for RNA tumor viruses by the biochemical or biophysical methods used. The results indicated that each type of mammalian cell currently used in the production of virus vaccines would be acceptable for these parameters of safety if similar control procedures were applied at the time the vaccines were manufactured.

Animals↗
PubMed1976

Elimination of bacteriophages from tissue culture serum by affinity chromatography.

Use of immunoadsorbents to remove bacteriophages from tissue culture serum was investigated. Immune globulins from rabbit antiserum prepared against phi V-1 phage were immobilized by covalent linkage to activated porous silica glass derivatives of p-aminoarylamine and to Sepharose-4B. Chromatographic columns of each material were used to filter samples of a fetal bovine serum into which had been introduced 8100 plaque-forming units of the phage per ml. Efficiency of removal was determined by plaque assays of phi V-1 phage recovered in the effluent fluids. Activated but uncoupled matrices nonspecifically removed from 49 to 59% of the phages introduced into the experimental serum. A reduction of 35 to 37% in phage content occurred in the serum after filtration through columns coupled to nonantibody protein. With specific immune globulins attached, the Sepharose-4B matrix reduced the concentration of phage in the serum below a detectable quantity. Noapparent alterations occurred in the growth-promoting property of serum filtered through the Sepharose-4B immunoadsorbent as measured by cloning efficiency of BHK-21, WI-38, and FRhL-2 cells. These experiments serve as a model system for use of immunoadsorbents for selective removal of bacteriophages and perhaps other extraneous microbial agents from tissue culture serum.

Adsorption↗
PubMed1976

The prevention of wound infections with the use of local antibiotics.

The local use of kanamycin, a broad spectrum antibiotic, has been successful in preventing primary wound infections. There have been no instances of drug reaction or sensitivity when kanamycin is used as a dilute topical irrigating solution. Secondary wound infections, which occurred in two cases, responded to local and systemic antibiotic therapy. Kanamycin can be recommended as an effective and safe topical antibiotic to prevent wound infections in foot surgery.

Administration, Topical↗
PubMed1976

Ultrastructural features of human galactosaemic fibroblasts: effects of different nutritional environments.

The ultrastructural characteristics of galactosaemic human fibroblasts exposed to media with various sugars were compared. Considerations of known biochemical pathways suggested that cells without the galactokinase enzyme and exposed to galactose would be functionally equivalent to cells in a medium without any sugar source. We found the ultrastructural characteristics of such cells to be consistent with that hypothesis. In addition, we unexpectedly found that homozygous galactosaemic fibroblasts, exposed to medium with glucose as the energy source, showed evidence of degeneration, such as autophagic vacuoles. Degenerative changes were not found in fibroblasts heterozygous for the galactokinase enzyme exposed to glucose. The implications and uses of these findings are discussed.

Autolysis↗