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Biomedical subjects

M Finland

Publications and source records attributed to M Finland.

At least 127 records · Page 7Linked to original sources
PubMed1969

In vitro effect of rifampin on mycobacteria.

Rifampin inhibited 20 strains of Mycobacterium tuberculosis in concentrations of 0.005 to 0.02 mug/ml in 7H-9 broth with Tween 80 and killed all or nearly all of the inoculum in four to eight times greater concentrations. In the same medium without Tween 80, as well as on 7H-10 agar, about 16 to 64 times these amounts were required to produce the same effect. Rifampin was also active against M. kansasii and some of the nonchromogenic mycobacteria. The incidence of mycobacterial cells resistant to rifampin within the cultures studied was in the range of one to four per 10(8) to 10(9) colony-forming units with concentrations of 4 to 125 mug of rifampin per ml. Only one of the Battey cultures and that of M. fortuitum yielded cells resistant to rifampin at 125 mug/ml but not at 500 mug/ml. The same strains yielded more than double that number of organisms resistant to streptomycin and up to 100 times more organisms resistant to isoniazid. All three drugs stopped the growth or reduced the mycobacterial population in growing cultures after contact for 24 to 48 hr. Complete inhibition of growth was produced by rifampin at 1.0 mug/ml in an average of 6 days and by streptomycin at 5.0 mug/ml in 3 days. After an average contact of 10.7 days with rifampin, five of seven strains resumed growth and all strains began regrowth after exposure to streptomycin for 9.4 days. The marked susceptibility of M. tuberculosis and of atypical mycobacteria to rifampin in vitro and the relatively low incidence of resistant mutants suggests that this agent may have clinical usefulness in the treatment of tuberculosis and some other mycobacterioses.

Aminosalicylic Acids↗
PubMed1968

Cephalexin and cephaloglycin activity in vitro and absorption and urinary excretion of single oral doses in normal young adults.

A large number of recently isolated bacterial pathogens were tested for susceptibility to cephalexin and cephaloglycin by the replica inoculating method. Strains of group A hemolytic streptococci, viridans (alpha and gamma) streptococci, pneumococci, gonococci, meningococci, and penicillin G-sensitive Staphylococcus aureus were all moderately to highly susceptible to both of these cephalosporin analogues, nearly all of the strains being two to eight (median four) times more susceptible to cephaloglycin than to cephalexin. The penicillin G-resistant, penicillinase-producing strains of S. aureus varied in their susceptibility; many were moderately resistant to both analogues, particularly to cephalexin. Strains of enterococci, Haemophilus influenzae, and most of the common gram-negative bacilli were moderately to highly resistant. Reducing the size of the inoculum had variable effects on inhibition by these drugs, depending on the species or strain. The activity of cephalexin was very little affected by pH of the medium within the clinical range or by incubation at 37 C in broth for up to 24 hr. In contrast, cephaloglycin in broth deteriorated rapidly at 37 C, and its activity was markedly reduced in alkaline medium. Both cephalexin and cephaloglycin were rapidly absorbed and excreted into the urine after single oral doses of 500 mg. Much higher levels were achieved and sustained with the former. Absorption of both analogues was delayed when taken with food, and the levels in the serum were significantly higher and better sustained when probenecid was also given. Very high concentrations of cephalexin were excreted into the urine during the first 4 hr, and the levels were still high in the 4- to 8-hr collection. The concentrations of cephaloglycin in the urine at these times were much lower. An average of 80 to 93% of the dose of cephalexin and 25 to 30% of the cephaloglycin were accounted for as active drug in the urine collected in 8 hr. Both analogues were well tolerated.

Adult↗
PubMed1968

Microassay for human and chick cell interferons.

The microassay for human and chick interferon described in this paper required much smaller amounts of samples and reagents and considerably less time and effort than the plaque reduction assay while yielding comparable results.

Animals↗
PubMed1968

Carbenicillin: activity in vitro and absorption and excretion in normal young men.

Carbenicillin is a new semisynthetic penicillin which differs from other penicillins in showing moderate antibacterial activity against Pseudomonas. Its activity in vitro is enhanced at low pH. Serum binding is of low order and does not appreciably alter activity. Strains of Pseudomonas exposed to subinhibitory concentrations of carbenicillin rapidly develop resistance by a mechanism that does not depend upon destruction of the drug. In normal subjects, high levels of anti-Pseudomonas activity are readily obtained in the urine after intramuscular injection. Levels of carbenicillin adequate to inhibit many strains of Pseudomonas can be achieved in serum only with an intravenous administration of a large dose. Carbenicillin appears to exhibit the same low degree of toxicity as do other penicillins.

Adult↗
PubMed1968

Measurement of three antibiotics (penicillin, cephalothin, and chloramphenicol) when present together in mixtures.

Benzylpenicillin, cephalothin, and chloramphenicol were measured individually and quantitatively when present together in mixtures at concentrations found in patients. The assay depended on the selective inactivation of two of the antibiotics, permitting the third to be assayed as if present alone. Agar seeded with a chloramphenicol-resistant, penicillinase-negative Staphylococcus aureus was used for a cylinder-plate assay of appropriately diluted fluid to determine the activity of either benzylpenicillin or cephalothin after either beta-lactamase inactivation of the former or ultraviolet light inactivation of the latter. Chloramphenicol was assayed with Sarcina lutea after appropriate beta-lactamase inactivation of both cephalothin and benzylpenicillin. Fluids containing various amounts of the three antibiotics were assayed by this method with less than 8% error. Procedures that fail to measure each antibiotic individually may give larger errors.

Biological Assay↗
PubMed1968

Enhancing effect on alkalinization of the medium on the activity of erythromycin against gram-negative bacteria.

The antibacterial activity of erythromycin was markedly enhanced by alkalinization of the culture medium or urine within the clinical range (pH 6.0 to 8.2). This effect was demonstrated against recent isolates of Escherichia coli, Klebsiella pneumoniae, Enterobacter sp., and Pseudomonas aeruginosa, as well as against Staphylococcus aureus and Streptococcus faecalis. The urine of normal volunteers was made alkaline by ingestion of sodium bicarbonate or acetazolamide (Diamox) during administration of 1.0 g of erythromycin every 8 hr; such urine was capable of inhibiting E. coli and K. pneumoniae even when diluted up to (in one instance) 128 times with broth of the same pH as the urine. Undiluted urine of the same subjects, without alkalinization, was seldom capable of inhibiting these organisms. The range of pH (6.6 to 8.6) over which the antibacterial effect was enhanced coincided with that over which there was decreasing ionization of a basic group.

Bacteria↗