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At least 667 records · Page 37Linked to original sources
PubMed1967

Conversion of DDT to DDD by pathogenic and saprophytic bacteria associated with plants.

Of 27 microorganisms examined, 23 plant pathogenic and saprophytic bacterial species were found to convert p,p' DDT to p,p' DDD under anaerobic conditions. The range of conversion of DDT (10 micrograms per milliliter) during an incubation of 14 days was from a trace to over 5 micrograms per milliliter, with the majority of the bacteria showing the greatest activity during the final 7-day period. There is evidence that metabolites of DDT other than DDD are also produced.

Alcaligenes↗
PubMed1972

Antimicrobial properties of natural phenols and related compounds: obtusastyrene and dihydro-obtusastyrene.

Factors influencing the antimicrobial properties of obtusastyrene and dihydro-obtusastyrene were studied. Both of these compounds were soluble in acetone, alcohol, and olive oil. In water, they were soluble at concentrations of 34 and 53 mug/ml, respectively. The minimal inhibitory concentrations against gram-positive bacteria and yeast were below 100 mug/ml. The compounds were not effective against gram-negative bacteria at 200 mug/ml or lower concentrations. With initial populations of cells greater than 10(6)/ml, the concentrations of these compounds required to prevent growth were greater than with lower cell populations. Changing the pH of the growth medium did not decrease the effectiveness of these two compounds in the pH range of 3 through 8. Both obtusastyrene and dihydro-obtusastyrene were rapidly bactericidal to Staphylococcus aureus and Bacillus cereus at 25 mug/ml.

Alcaligenes↗
PubMed1976

Active metabolites of isoxazolylpencillins in humans.

Metabolites of the isoxazolylpenicillins that still possessed antibacterial activity were shown to be present in urine and serum. In healthy subjects, the amounts excreted in urine were low; 10 to 23% of the excreted penicillin activities represented the metabolites. The highest amount of metabolite in urine was found for oxacillin, and the lowest was found for flucloxacillin. No extreme differences in the amounts of metabolite excreted were observed when the compounds were administered orally or intravenously. In one healthy subject metabolite levels were estimated for cloxacillin in serum. Very low levels were found, i.e., about 9% of the activity. In subjects with highly impaired renal function, the metabolite may represent up to 50% of the total level of penicillin in serum. The antibacterial activities of the different metabolites were of the same order of magnitude as those of the respective parent compounds. Also, the activity against benzylpenicillin-resistant staphylococci was retained. It is not likely that the formation of the active metabolites should influence therapeutic results.

Administration, Oral↗
PubMed1977

Stability of cephalosporins in horse serum.

The antibiotic activity of cephalothin, cephaloridine, cephalexin, cephaloglycin, cefazolin, and cefamandole was determined after storage for up to 30 days in horse serum at -10 and 4 degrees C. Cephalothin, cefamandole, cefazolin, and cephalexin were stable for at least 30 days at -10 degrees C, whereas cephaloridine lost 29% of its initial activity and cephaloglycin lost more than 50%. Cefamandole, cefazolin, and cephalexin could only be stored for 3 days at 4 degrees C without significant loss in activity, whereas cephalothin, cephaloridine, and cephaloglycin could be stored for only 1 day. Repeated freezing and thawing had a detrimental effect on the stability of cephaloridine.

Animals↗
PubMed1979

Dissociated resistance among cephalosporins.

When disks containing cefuroxime (CXM) or HR 756 (756) were placed next to cefoxitin (FOX) on plates inoculated with Enterobacter resistant to FOX, there was marked flattening of the zones of inhibition produced by CXM or 756, but colonies growing near the CXM or 756 disks were found to be fully susceptible to these drugs on retesting. In contrast, when a checkerboard titration with CXM or 756 and FOX was done in broth, organisms growing in the presence of high concentrations of either of the former plus FOX were found to be resistant on retesting. Broth cultures of Enterobacter were found to contain small numbers of mutants which were resistant to and inactivated CXM and 756. Evidence is presented suggesting that the addition of FOX induces similar properties in the whole culture, which then becomes resistant to all of the nine cephalosporins tested and to four of six penicillins tested. Such cultures rapidly reverted to susceptible when FOX was removed or inactivated, and an explanation is offered as to why this did not happen in fluid media.

Cefoxitin↗
PubMed1981

Pharmacokinetics of cefamandole in osseous tissue.

The ability of cefamandole to cross osseous capillary membranes and its concentrations in interstitial fluid spaces are studied in canine cortical bone. Extraction studies were performed by using indicator dilution techniques and demonstrated that cefamandole readily traversed osseous capillary membranes. Volume-of-distribution studies demonstrated that cefamandole was distributed in the plasma and interstitial fluid spaces of cortical bone. There was a direct correlation between the calculated concentrations of cefamandole in the interstitial fluid spaces of bone and the simultaneous serum levels determined by bioassay in animals in which a steady-state equilibrium had been achieved. This suggests that the less expensive and more readily available serum bioassay technique is more useful than bone bioassays in monitoring the osseous concentrations of cefamandole.

Animals↗
PubMed1982

Determination of apalcillin and its metabolites in human body fluids by high-pressure liquid chromatography.

We describe two methods for the quantitative analysis of apalcillin and its metabolites in serum and urine by reverse-phase high-pressure liquid chromatography (HPLC), a fast isocratic method for the parent drug, and a gradient method that allows the simultaneous assay of two metabolites. Serum was deproteinized with acetonitrile, and urine was diluted with buffer solution. The detection limit was about 0.5 micrograms/ml at a detection wavelength of 254 nm and 1.5 micrograms/ml at 310 nm. Within-batch precision (coefficient of variation) varied from 10.2 to 1.1% for concentrations of 7.8 and 185.3 micrograms/ml of serum, respectively. Recovery rates of 95.1 and 97.7% were found in spiked sera. Results obtained by HPLC correlated well with those from a standard microbiological assay (agar diffusion test); the resulting bivariate regression equation for serum was y-bioassay = 2.5 micrograms/ml + 0.992 X xHPLC, and that for urine was ybioassay = 12.0 micrograms/ml + 1.009 X xHPLC. At a detection wavelength of 315 nm, no interferences were observed in 10 healthy volunteers. Healthy subjects who were given 2 g of apalcillin intravenously excreted 18% of the parent drug within 24 h in the urine. Two inactive compounds were furthermore identified in urine as the isomeric forms of the penicilloic acids. Their excretion within 24 h amounted to 6.9 and 11.2% of the dose.

Ampicillin↗
PubMed1974

Preparation of succinyl neocarzinostatin.

All amino groups in a proteinous antitumor antibiotic, neocarzinostatin, were reacted with succinic anhydride yielding bis-N-succinyl neocarzinostatin which retained biological activity in vitro against human cell lines and a bacterium. Amino groups in neocarzinostatin do not appear to play an important role in the activity.

Antibiotics, Antineoplastic↗
PubMed1974

Studies on the absorption, distribution, metabolism, and excretion of propionylmaridomycin in rats.

The absorption, distribution, metabolism, and excretion of propionylmaridomycin was investigated in the rat by using [(14)C]propionylmaridomycin. Propionylmaridomycin was absorbed from the gastrointestinal tract at a relatively rapid rate and was readily distributed into tissues. Among the tissues examined, liver, kidney, and lung showed a remarkably higher level of the radioactivity than plasma, while distribution of the radioactivity into brain was little. However, a significant accumulation of the radioactivity in tissues was not observed. Excretion of the radioactivity was mainly via the fecal route and the high fecal recovery was accounted for by unabsorbed drug and biliary excretion of the drug and/or its metabolites. Tissue distribution of antimicrobial activity was also investigated and lung was found to show the highest antimicrobial activity among any tissues examined. Propionylmaridomycin was completely converted to several metabolites by the rat and the presence of at least three components was confirmed as biologically active metabolites. Of these metabolites, 4''-depropionyl-9-propionylmaridomycin was identified, which was the major metabolite in tissues, plasma, and urine.

Aminoglycosides↗
PubMed1982

Antimicrobial characteristic of insoluble alkylpyridinium iodide.

Insoluble and soluble alkylpyridinium iodides (C8 to C18) were synthesized. The insoluble agents were quaternized 4-vinylpyridine-divinylbenzene copolymers. The insoluble agent [C12(50)] that contained 50% divinylbenzene and had a C12 alkyl chain was selected as the most suitable insoluble agent. C12(50) showed poor durability of the antibacterial activity, but C12(50), which had lost the activity, was refreshed by washing with ethanol. This washing became ineffective after a few cycles of antibacterial treatment and refreshment. Such C12(50) recovered the activity upon 1.0 N NaOH treatment. The antibacterial activity of C12(50) depended on its surface area. It showed high antimicrobial activity against gram-positive bacteria and also showed activity against gram-negative bacteria and yeasts. But the activities of C12(50) and laurylpyridinium iodide solution were different against some microbes. The antibacterial activities of the agents were investigated against Escherichia coli and Micrococcus luteus under various conditions. The activity of C12(50) was higher at a higher temperature or at a lower cell concentration. The activity of C12(50) decreased on addition of NaCl, glucose, or bovine albumin to the cell suspension or in 0.01 M sodium-potassium phosphate buffer. C12(50) showed less activity when cells were mixed with dead cells or the supernatant of dead cells killed in an autoclave. The mode of action of the laurylpyridinium iodide solution against E. coli and M. luteus was similar to that of C12(50) except for the influence of E. coli cell concentration.

Alkanes↗
PubMed1966

Simplified, accurate method for antibiotic assay of clinical specimens.

Large glass plates are used for this modified agar-well diffusion assay method, allowing up to 81 replications on a single plate. With a specially designed agar punch, it is possible to prepare the small agar wells very quickly. The saving in serum resulting from fewer replications of standards with the large plates, and the small volume of the agar wells, makes it economically feasible to use pooled human serum for the standard antibiotic solutions. Methods are described for preparing the standard solutions, and for providing controls for the deterioration of standards and unknowns. Procedures for preparing and maintaining the commonly used assay organisms are presented. Serum specimens are tested directly rather than diluting them to a narrow range of antibiotic concentrations. This is possible because of a procedure for calculations that recognizes the curvilinear relationship between zone sizes and antibiotic concentrations. Adaptation of this method to a number of the commonly used antibiotics is described. With this method, it has been possible to test large numbers of clinical specimens in a minimal time, and with accuracy consistently better than 10%.

Ampicillin↗