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Biomedical subjects

J Lyon

Publications and source records attributed to J Lyon.

51 records · Page 3Linked to original sources
PubMed1982

Peptide formation in the presence of metal ion protecting groups. II. Determination of the optical purity of amino acids and peptides bound to pentaamine cobalt (III).

A quantitative study of the degree of racemization induced by the [(NH3)5Co-(III)-] protecting group when bound to the C-terminal of the amino acids Leu, Phe, and His, as (formula; see text) has been carried out. Racemization was determined by forming the diastereomeric cobalt dipeptides [(Leu)(AA)Co(III)(NH3)5] where AA = L-Leu, L-Phe, and L-His; after cobalt removal (using NaBH4), the peptide diastereomers were analyzed quantitatively using an amino acid analyzer. No racemization was observed within experimental error (0.3%) as a result of the substitution of the [(NH3)5Co(III)-] group on the amino acids and peptides studied.

Amino Acids↗
PubMed1981

Steady-state moxalactam kinetics: comparisons with other cephalosporins.

Moxalactam is a new beta-lactam antimicrobial with an extended spectrum. Serum concentrations were determined in 14 patients at steady state using bioassay and high-pressure liquid chromatography methods. Mean peak and trough serum concentrations were 195 and 29.5 micrograms/ml for the 20-gm dose and 214 and 28.8 micrograms/ml for the 3-gm dose. Peak and trough levels exceeded the minimum inhibitory concentration of the infecting bacteria in 100% and 67% of the patients. The 3-gm dose is recommended for infections caused by Pseudomonas aeruginosa and other organisms with higher minimum inhibitory concentrations. Half-lifes ranged from 1.7 to 5.7 hr and reflected the varying renal functions of the patients. A relationship (r = 0.878, p less than 0.001) between creatinine clearance and elimination rate constant was established by bivariant linear regression analysis.

Adult↗
PubMed1981

Measurement of serum and tissue concentration of moxalactam using high pressure liquid chromatography.

We describe a sensitive high pressure liquid chromatographic (HPLC) procedure for the analysis of the new beta-lactam antibiotic moxalactam. Conditions are described for either measurement of total drug concentration or the concentration of the individual isomers. The proteins in a 1.0 ml plasma sample are denatured with isopropyl alcohol which is then extracted into a chloroform reagent, leaving the drug in the aqueous phase. An aliquot is then injected into a mu-bondapak phenyl column. A similar extraction procedure was employed for tissue homogenates. Linear regression analysis and comparison of the HPLC assay with the microbiological assay gave a correlation coefficient of 0.97. Analysis of tissue samples indicated that significant concentrations of moxalactam were obtained at the site of infection.

Biological Assay↗
PubMedDate not supplied

Third-generation and investigational cephalosporins: I. Structure-activity relationships and pharmacokinetic review.

The structure-relationships and pharmacokinetic properties of the new second- and third-generation cephalosporins are reviewed. The new second-generation cephalosporins include ceforanide, cefotiam, and cefuroxime. The third-generation cephalosporins include cefmenoxime, cefoperazone, cefotaxime, cefsulodin, ceftazidime, ceftizoxime, ceftriaxone, and moxalactam. These new cephalosporins are semisynthetic analogs with different chemical substitutions on a 7-aminocephalosporanic nucleus. As a result of these chemical modifications, improvements in the antibacterial spectrum as well as pharmacokinetic properties have occurred. In general, the new cephalosporins have longer half-lives, higher and prolonged serum concentrations, and increased cerebrospinal fluid penetration. Selected cephalosporins also have increased biliary tract concentrations. A classification scheme for these new agents, based on generation and susceptibility to Pseudomonas aeruginosa, is presented.

Bacteria↗
PubMedDate not supplied

Respiratory syncytial virus and ribavirin therapy: winter 1987-spring 1988. A report of 74 cases treated at Providence Hospital, Anchorage, Alaska.

Seventy-four pediatric cases of Respiratory Syncytial Virus lower respiratory tract infection were treated at Providence Hospital, Anchorage, Alaska between September 1, 1987 and April 30, 1988. These patients are described with illustrative case reports. Twenty-one patients were treated with Ribavirin and these patients are further analyzed as a special interest group. A disproportionate number of the Ribavirin treated group were Alaskan Natives. In the discussion we address concerns of possible toxicity of Ribavirin and current recommendations for patient selection for treatment with Ribavirin.

Adolescent↗