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P Actor

Publications and source records attributed to P Actor.

At least 37 records · Page 2Linked to original sources
PubMed1981

Analysis of parameters affecting the hemagglutination activity of Escherichia coli possessing colonization factor antigens: improved medium for observing erythrocyte agglutination.

The hemagglutination (HA) activity of two strains of Escherichia coli, each possessing different colonization factor antigens (CFA), was examined under different test conditions. The effects of ionic strength, temperature, pH, cations, and reaction surface on erythrocyte (RBC) agglutination were analyzed. Strain H-10407 (CFA/I) caused the agglutination of human, bovine, and chicken RBC, whereas strain CL-9699 (CFA/II) agglutinated only bovine and chicken RBC. The HA activity of both strains increased with decreasing ionic strength, pH, and temperature, the effects of temperature being negligible at low ionic strength. When accounting for ionic strength, the presence of Ca2+, Mg2+, Fe2+, or Fe3+ ions did not increase the HA activity of these bacteria. Optimum conditions for HA of reactive RBC by bacteria included low ionic strength (less than 50 mM) and slightly acidic pH (6.0 to 7.0). Use of a low-ionic-strength medium permitted application of microtitration methods to visualize the HA reactions. Storage of RBC in low-ionic-strength medium did not change their HA properties, and the use of this medium proved superior to saline in overcoming HA variation observed with different preparations of RBC.

Animals↗
PubMed1981

Cefonicid: a stable beta-lactamase inhibitor.

The stability of cefonicid (SK&F 75073) towards representatives of six major classes of beta-lactamases was determined using a spectrophotometric assay. Cefonicid was stable to hydrolysis by the Type I enzyme from Enterobacter cloacae and by the enzyme from the anaerobe, Bacteroides fragilis. It was 6 to 7 times more stable than cefamandole to the Type IIIA and B enzymes from Escherichia coli, a little less stable than this antibiotic to the Type V enzyme from E. coli, and of equal stability to the Type IV enzyme from Klebsiella aerogenes. Cefonicid was a non-competitive inhibitor (Ki of 0.8 x 10(-6)M) of cephalothin hydrolysis by the Type I enzyme.

Cefamandole↗
PubMed1980

Serum protein binding alterations of selected cephalosporin antibiotics by fatty acids and their derivatives.

Saturated fatty acids containing 10--14 carbon atoms were more potent inhibitors of serum protein binding than those containing shorter or longer carbon chains. Introduction of unsaturation into chains containing 16 or 18 carbons increased their inhibitory potency. Triglycerides and fatty acid esters, chlorides, thiols, and amides had no inhibitory activity. When inhibition was observed, it was concentration dependent and occurred when the molar ratio of fatty acid to protein equaled or exceeded three. The change in percent serum protein binding in the presence of an effective inhibitor was the greatest with cephalosporins that were most highly bound in the absence of an inhibitor.

Blood Proteins↗
PubMed1980

A new many-purpose culture medium for chemotherapeutic and microbiologic studies.

A new semisynthetic culture medium was prepared and found to serve many useful purposes in chemotherapeutical research and also in diagnostic microbiology. It contains 0.5% peptone, 0.1% glucose and is supplemented with 10% 10% McIlvaine's buffer. The medium is pH-stable and, being almost colorless, it is suitable for turbidimetric studies and enzymatic experiments which involve color-changes. For in vitro chemotherapeutic experimental studies it is a useful medium and, in certain cases, it behaves like an almost antagonist-free medium. Used as broth or in agar-base, it supports the growth of all of the 280 clinically important strains studied, including aerobic bacteria, Candida and Trichophyton. It promotes the germ tube formation of C. albicans and C. stellatoidea.

Bacteria↗
PubMed1979

In vitro and in vivo laboratory studies on three hydroxyiminophenylacetyl cephalosporins with particular reference to SK&F 80303, an unusually long-acting cephalosporin.

Three cephalosporins with 7-(2-hydroxyiminophenylacetamido) side chains (SK&F 79433, 80000 and 80303), differing in their 3-substituents, exhibited similar broad-spectrum antibacterial activity in vitro against strains of Staphylococcus aureus, Streptococcus faecalis and various Gram-negative bacilli. All three were active in vivo (s.c., mouse) against S. aureus, Escherichia coli or Klebsiella pneumoniae, but they differed significantly in serum pharmacokinetic profiles. SK&F 80303 produced high and extremely prolonged serum levels and protected mice when administered up to 24 hours prior to challenge with beta-lactamase-producing S. aureus or K. pneumoniae. It was resistant to hydrolysis by beta-lactamases from S. aureus, and variably so to beta-lactamases from E. coli strains. SK&F 80303 was bacteriolytic to logarithmically growing S. aureus, E. coli, Proteus mirabilis, K. pneumoniae and Enterobacter cloacae (partially). SK&F 80303 illustrates further the effect of the 3-sulfoalkyltetrazole substituent on the pharmacokinetic properties of cephalosporins. Its combined biological properties make it a possible candidate for therapeutic and long-term prophylactic use.

Animals↗
PubMed1978

SK&F 75073, new parenteral broad-spectrum cephalosporin with high and prolonged serum levels.

SK&F 75073, a new parenteral cephalosporin, was found to have broad in vitro and in vivo antibacterial activity including isolates usually resistant to cephalothin and cefazolin. This activity included indole-positive Proteus and Enterobacter species and some Serratia isolates. Proteus mirabilis strains were particularly susceptible, as were Haemophilus influenzae and Neisseria species. The activity of SK&F 75073 against gram-positive bacteria was poorer than that of the control cephalosporins. This cephalosporin is highly bound to serum proteins, and a loss in in vitro activity was observed in the presence of serum. Parenteral administration of SK&F 75073 to experimental animals (mice, dogs, squirrel monkeys) resulted in high and prolonged serum levels when compared with cefazolin and other injectable cephalosporins. This favorable serum profile was reflected in the excellent protection observed in mice infected with pathogenic bacteria.

Animals↗
PubMed1978

Distribution in normal and inflammatory tissue of a new semisynthetic cephalosporin, SK&F 75073.

SK&F 75073 is a new cephalosporin with broad spectrum antibacterial activity. SK&F 75073-14C and cefazolin-35S were administered separately to groups of rats as a single intramuscular dose of 20 mg/kg. Tissues with highest drug levels 15 minutes following dose were as follows: (SK&F 75073/cefazolin levels), kidney - 86/70 microgram/g, liver - 33/22 microgram/g, lung - 29/17 microgram/g, heart - 23/10 microgram/g, adrenal - 13/7 microgram/g. Plasma levels at peak were 134 microgram SK&F 75073/ml (half-life, 1.9 hours) and 72 microgram cefazolin/ml (half-life, 0.75 hours). Dose excreted in 24 hours was: SK&F 75073, urine 66% and feces 27%; cefazolin, urine 96% and feces 2%. Both antibiotics were also administered, at 20 mg/kg, to rats with the carrageenan-induced inflammatory pouches. Exudate from these pouches contained from 2 to 10 times more SK&F 75073 than cefazolin. Radioassay and bioassay of these substances in the exudate gave similar results. Serum protein binding ranged from 96 approximately 98% for SK&F 75073 and 34 approximately 69% for cefazolin. Data indicated that highly protein bound SK&F 75073 enters tissues and tissue fluid to a greater extent than the lesser bound but therapeutically proven antibiotic agent cefazolin.

Animals↗
PubMed1978

Semiautomated turbidimetric microbiological assay for cefazaflur.

A quantitative semi-automated turbidimetric bioassay for cefazaflur, using Streptococcus faecium as the indicator, is described. Assays were run at pH 6.5 approximately 7 for 3.75 hours at 37 degrees C using 2 approximately 12 microgram cefazaflur per ml assay broth for standards. The dose response line was plotted point to point using the natural log of the absorbance vs natural log of the concentration. This assay is both accurate and precise and is more rapid than traditional plate assays for antibiotics.

Biological Assay↗
PubMed1978

Semisynthetic cephalosporins with antifungal activity: laboratory studies on 2-pyridinethiol 1-oxide cephalosporins.

Cephalosporins are chemotherapeutic agents whose spectrum and use are limited to antibacterial activity. Therefore, it was of interest to find several new semisynthetic cephalosporins which possess in vitro antifungal activity against Trichophyton mentagrophytes, Candida albicans and certain other yeasts. Five new cephalosporins containing the 2-pyridinethiol 1-oxide grouping were examined. Four with this heterocyclic moiety in the 3-position were found to have activity. One with the grouping in the 7-acyl-side chain was inactive. The degree of the antifungal activity was influenced by the substituent at the 7-position. The cephalosporin with a p-hydroxyphenylglycyl side chain was the most potent against the fungal strains studied. Despite this in vitro antifungal activity, none of the compounds protected mice against a systemic Candida albicans infection. All of these cephalosporins had broad spectrum in vitro and in vivo antibacterial activity.

Animals↗
PubMed1978

Biological and chemotherapeutic studies on three semisynthetic cephamycins.

Three semisynthetic cephamycin antibiotics (7alpha-methoxy-cephalosporins), SK&F 73678, SK&F 83088 (CS-1170) and cefoxitin, have been found to possess favorable biological and chemotherapeutic properties. All three cephamycins are active in vitro against strains of Staphylococcus aureus and a variety of gram-negative bacilli. Beta-lactamase producing organisms including indole-producing Proteus spp., Enterobacter spp. and Serratia strains as well as certain anaerobic bacteria were found to be susceptible to these antibiotics. SK&F 73768 showed somewhat better MIC values than cefoxitin against multiple strains of bacteria. Strains of Pseudomonas aeruginosa and group D streptococci are essentially insensitive to these compounds. Their binding to serum proteins is relatively low. In mice, cefoxitin showed the most favorable pharmacokinetics with respect to peak serum level, serum half-life and urinary recovery. These cephamycins protected mice experimentally infected with a variety of bacterial strains. All three compounds are rapidly bacteriolytic to the logarithmically growing Escherichia coli and belatedly so to Staphylococcus strains with complete sterilizing effect. SK&F 73678 and SK&F 83088 showed activity and potency comparable to or better than cefoxitin and thus can be considered candidates for clinical study.

Animals↗
PubMed1977

Semisynthetic cephalosporins. Synthesis and structure-activity relationships of analogues with 7-acyl groups derived from 2-(cyanomethylthio)acetic acid or 2-[(2,2,2-trifluoroethyl)thio]acetic acid and their sulfoxides and sulfones.

The synthesis and in vitro and in vivo activities of a series of cephalosporins having side chains derived from 2-[(2,2,2-trifluoroethyl)thio]acetic acid or 2-(cyanomethylthio)acetic acid and with acetoxymethyl or 3-heterocyclic thiomethyl substituents at the 3 position are described. In both series, increasing the oxidation state of the side-chain sulfur atom from sulfide to sulfoxide/sulfone decreased the in vitro gram-positive activity, but the effect on gram-negative activity was variable and less pronounced. The protective effectiveness in mice infected with Escherichia coli increased as the oxidation level of the side-chain sulfur was raised from sulfied to sulfoxide/sulfone. Replacement of the 3-acetoxymethyl by a 3-heterocyclic thiomethyl group resulted in overall improvement of activity both in vitro and in vivo for all oxidation states.

Acetates↗