3,4-Dihydro-2-phenyl-2H-pyrano[2,3-b]pyridines with potent antirhinovirus activity.

A general synthesis to the title compounds 1, substituted in the 6-position and on the phenyl ring, is outlined. Eighteen analogues were compared with respect to in vitro activity against rhinovirus types 1A, 9, and 64. Compounds 1c and 1h, the 6-bromo- and 6-(methylsulfonyl)-3',4'-dichlorophenyl analogues, afforded median MIC50 values against 23 rhinovirus serotypes of 0.05 and 0.13 micrograms/mL, respectively. Mice dosed orally with 200 mg/kg of 1c or 1h exhibited serum levels well in excess of each compound's MIC50, indicating that some analogues have the potential to be orally effective drugs.

In vitro and in vivo anti-picornavirus activity of some p-benzoylphenoxypyridines.

Fifteen p-benzoylphenoxypyridines were initially evaluated for their in vitro activity against rhinoviruses (RV) 1A, 2 and 64 and coxsackie virus (Cox) A21 and for their oral prophylactic and therapeutic activity in Swiss albino mice lethally challenged with Cox A21. One compound, (4-[(5-methylsulfonyl-2-pyridinyl)oxy]phenyl) phenyl methanone, was selected for additional evaluation. These studies showed the compound to possess MIC50 values of less than or equal to 5 micrograms/ml against only 6 of 20 (30.0%) RV serotypes tested. In contrast, the compound was active at concentrations of less than or equal to 5.0 micrograms/ml against 10 of 12 (83.3%) enteroviruses evaluated. In vivo studies showed the compound to significantly protect mice lethally infected with Cox A21 after a single oral dose of 37.5 mg/kg (P less than 0.02) and during a regimen of continuous oral doses of at least 4.7 mg/kg per day (P less than 0.001). Mechanism of action studies indicated that the compound inhibits picornavirus uncoating or some earlier virus-host cell-associated event. Isotopic studies show that (4-[(5-methylsulfonyl-2-pyridinyl)oxy]phenyl) phenyl methanone perturbs HeLa cell macromolecular synthesis at concentrations of as low as 3.12 micrograms/ml. This concentration is only 4-fold higher than the concentration of compound necessary to inhibit Cox A21 RNA synthesis by 90%. This narrow therapeutic ratio limits the potential clinical utility of this compound to all but the most serious picornavirus infections.

Mechanism of action of the antiviral compound MDL 20,610.

The purpose of this study was to probe the antirhinovirus (RV) mechanism of action of MDL 20,610. Evaluation of the compound's effects on RV RNA synthesis, uncoating of neutral red-sensitized RV, plasma membrane penetration by RV, stabilization of RV against heat (56 degrees C) and low pH (5.0) inactivation, and studies with MDL 20,610-resistant RV mutants indicate that MDL 20,610 binds directly to the RV capsid with subsequent inhibition of acid-mediated virion uncoating.

Antipicornavirus activity of some diaryl methanes and aralkylaminopyridines.

Sixteen diarylmethanes and ten aralkylaminopyridines were initially evaluated for their in vitro activity against rhinoviruses 1A, 2 and 64 and against coxsackievirus A21 and for their oral prophylactic and therapeutic activity in mice challenged with coxsackievirus A21. Based on these preliminary studies the diarylmethane (3,4-dichlorophenoxy)-(5 methylsulfonyl-2-pyridinyl)-methane and the aralkylaminopyridine (2-(3,4-dichlorobenzylamino)-5-methylsulfonylpyridine were compared with their oxygen bridged analogue 2-(3,4-dichlorophenoxy)-5-(methylsulfonyl)pyridine for in vitro activity against a larger number of picornaviruses and for their in vivo protective efficacy in dose response assays. All three compounds exhibit similar in vitro activity inhibiting 12 to 15 (52.2-65.3%) of the 23 picornaviruses tested at concentrations of less than 5.0 micrograms/ml. However, the aralkylaminopyridine was found to be the most active in vivo; significantly protecting coxsackievirus A21 challenged mice after a single oral dose of 37.5 mg/kg (P less than or equal to 0.05) and during a continuous oral dose regimen of as low as 18.8 mg/kg per day (P less than 0.01).

Bioassay quantitation of ramoplanin in human and in nonprimate sera.

This study developed and validated a bioassay for ramoplanin in human, dog, rabbit, and rat sera. Mean analyte recoveries and coefficients of variation for duplicate assays with each serum using coded and spiked (30-720 ng/ml) samples ranged from 93.5% to 106.3% and from 1.8% to 5.4% respectively. All correlation coefficients were > 0.99 and, for each serum, there was no significant difference in overall analyte recovery between the 2 test days.

Effect of protein on ramoplanin broth microdilution minimum inhibitory concentrations.

Ramoplanin is a glycolipodepsipeptide antibiotic active against Gram-positive bacteria. We observed that microdilution minimum inhibitory concentrations (MICs) were higher than those obtained in glass tubes or by agar dilution. Initial studies showed that these differences disappeared when 30% bovine serum was added to the broth. Further studies showed that addition of 0.01% bovine serum albumin (BSA) to the broth lowered the microdilution MICs for staphylococci, streptococci, and enterococci by four- to 32-fold. This phenomenon occurred in several commonly used growth media and in different types of commercially available microtiter trays. Precoating of the microtiter wells with a dilute solution of BSA (0.02%) had the same effect. It seems likely that ramoplanin adsorbs to plastic surfaces and is lost from solution, and that protein masks the sites of adsorption. Ramoplanin MICs may be reliably determined by broth microdilution if a small amount of protein is added to the diluent.

Comparative in vitro activity of teicoplanin and vancomycin against United States teicoplanin clinical trial isolates of gram-positive cocci.

In this study, the in vitro activity of teicoplanin and vancomycin was directly compared against 503 Gram-positive cocci isolated during the U.S. teicoplanin clinical trials. Both antibiotics were equally active against oxacillin-sensitive Staphylococcus aureus, oxacillin-sensitive and oxacillin-resistant Staphylococcus epidermidis, and other coagulase-negative staphylococci, except Staphylococcus haemolyticus. Teicoplanin was fourfold more active than vancomycin against oxacillin-resistant S. aureus (MIC90, 0.5 vs. 2.0 micrograms/ml), whereas vancomycin was more active than teicoplanin (MIC90, 2.0 vs. 8.0 micrograms/ml) against oxacillin-resistant S. haemolyticus. Teicoplanin was two- to eightfold more active than vancomycin against the streptococci and enterococci tested.

Evaluation of the teicoplanin broth microdilution and disk diffusion susceptibility tests and recommended interpretive criteria.

Comparative teicoplanin in vitro susceptibility data were generated for 1201 Gram-positive US clinical trial isolates using standardized broth microdilution and disk diffusion techniques. Based on the results of this study, the following interpretive criteria for teicoplanin are recommended: for MIC tests, less than or equal to 8 micrograms/ml = susceptible, 16 micrograms/ml = moderately susceptible, and greater than or equal to 32 micrograms/ml = resistant; and for disk (30 micrograms) tests, greater than or equal to 14 mm = susceptible, 11-13 mm = intermediate, and less than or equal to 10 mm = resistant.

Comparison of biological and chemical assays for the quantitation of rifapentine in human plasma.

The purpose of this study was to establish the correlation between biological and chemical assays for the quantification of rifapentine in human plasma. The bioassay was found to overestimate antibiotic plasma concentration when compared to the high-performance liquid chromatography (HPLC) assay for rifapentine (r = 0.9538, n = 220). This was because of the presence of varying amounts of the biologically active 25-O-desacetyl metabolite in the test samples. A better correlation (r = 0.9804, n = 220) was observed when the bioassay data were compared to combined parent-metabolite HPLC values. Such correlative data are necessary adjuncts in the establishment of antibiotic susceptibility test breakpoints.

Bioassay of teicoplanin in serum containing rifampin or a beta-lactam antibiotic.

The purpose of this study was to develop bioassays for the measurement of teicoplanin in serum containing rifampin or a beta-lactam antibiotic. Use of rifampin-resistant Bacillus subtilis as indicator organism or pretreatment of the serum sample with Bacillus cereus penicillinase Type I (nafcillin, ticarcillin, mezlocillin) or Type II (cefazolin, cefuroxime, ceftazidime, ceftriaxone) effectively eliminated assay interference. Validation bioassays performed on two separate days utilizing triplicate coded serum samples containing 0 to 200 micrograms teicoplanin in combination with 40 micrograms/ml rifampin or 200 to 500 micrograms/ml beta-lactam showed no significant differences (p greater than 0.05, two-way analysis of variance) in analyte recovery between assay days. Regression analysis of each teicoplanin/rifampin or teicoplanin/beta-lactam data set yielded slope values of 0.92 to 1.01, intercept values of -0.45 to 0.84 and correlation coefficients of 0.9925 to 0.9990. Thus, serum teicoplanin can be quantitated accurately, precisely, and reproducibly in patients receiving concomitant rifampin or beta-lactam chemotherapy.

Pharmacokinetics and bioavailability of a new formulation of teicoplanin following intravenous and intramuscular administration to humans.

Pharmacokinetics, bioavailability, and local tolerance (at the site of intramuscular administration) of a new formulation of teicoplanin (400 mg/3 mL) were investigated in 24 normal, healthy, male volunteers. A single dose of 6 mg/kg was administered intravenously and intramuscularly using a randomized crossover design. Volunteers and investigator were blinded as to the route of administration; placebo was administered by the other route. Blood and urine samples were collected for 21 days and were analyzed for microbiological activity. The median (range) pharmacokinetic parameters of teicoplanin following single-dose iv administration were as follows: steady-state volume of distribution of 1.6 (1.2-2.8) L/kg; total clearance of 10.2 (8.6-15.1) mL/h/kg; renal clearance of 10.0 (7.9-13.8) mL/h/kg; and terminal disposition half-life of 168 (111-278) h. Following single-dose im administration, significantly more subjects complained of pain following administration of teicoplanin (58%) compared with placebo (4%). Teicoplanin was completely absorbed with a median (range) peak serum concentration of 12.3 (6.6-37.5) micrograms/mL occurring at a median (range) time of 4.1 (0.7-6.1) h. Since the 90% confidence interval for the ratio of areas under the serum concentration-time curve falls within the range of 80 to 120%, the extent of systemic absorption of teicoplanin following im administration is equivalent to that following iv administration.

The antimicrobial activity of vancomycin in the presence and absence of sodium carboxymethyl starch.

The purpose of this work was to determine any effects the presence of sodium carboxymethyl starch may have on the antimicrobial activity of vancomycin given a previously described interaction between vancomycin and sodium carboxymethyl starch. In particular, the in-vitro activity of vancomycin against two clinically relevant bacteria, Staphylococcus aureus and Enterococcus faecalis, was studied in the presence of varying concentrations of sodium carboxymethyl starch. From two independent studies conducted using an agar dilution method, it appeared that the binding of vancomycin to sodium carboxymethyl starch had no effect on the in-vitro antimicrobial activity of vancomycin. The minimum inhibitory concentration of vancomycin against S. aureus in the presence of as much as 1 mg mL(-1) sodium carboxymethyl starch was similar to that of the control where no sodium carboxymethyl starch was added (1-4 microg mL(-1) vs 1-2 microg mL(-1), respectively). Likewise, the minimum inhibitory concentration of vancomycin against E. faecalis in the presence of 1 mg mL(-1) sodium carboxymethyl starch was also similar to that of the control where no sodium carboxymethyl starch was added (1-4 microg mL(-1) vs 1-4 microg mL(-1), respectively). However, there may be factors in the in-vitro method, such as high ionic strength, that could disrupt the interaction between vancomycin and sodium carboxymethyl starch. Therefore, the possibility of diminished vancomycin activity in-vivo cannot be ruled out. A small percentage (8-10%) of vancomycin was determined to be bound to sodium carboxymethyl starch in broth media. Given these results, the impact of sodium carboxymethyl starch on the in-vitro antimicrobial activity of vancomycin is expected to be minimal. Binding studies could not be conducted with gelled agar due to its semi-solid state.

A field with a liver measles-mumps-rubella vaccine.

Three lots of Lirutrin (measles-mumps-rubella live, attenuated virus vaccine) were evaluated in a double-blind, placebo-controlled clinical study involoving 273 children. The vaccine consisted of a combination of Schwarz strain measles, Jeryl Lynn strain mumps, and Cendehill strain rubella vaccine viruses. The frequency of positive clinical findings was essentially the same in susceptiable vaccinees, immune vaccinees, and placebo recipients; indicating that the observed symptoms were not caused by the vaccine. Antibody assay of paired serum samples revealed that measles, mumps, and rubella seroconverison rates in triple susceptible vaccinees were excellent, ranging from 96 to 98 per cent with all three lots combined. Results of this study show that Lirutrin trivalent vaccine is well tolerated and highly effective.

Effect of rifampin and its cyclopentyl analogue, MDL 473, on the expression of delayed type hypersensitivity to oxazolone.

The purpose of this study was to determine the effect of rifampin and its cyclopentyl analogue, MDL 473, on delayed type hypersensitivity (DTH) using a murine model. Neither compound has any significant effect on DTH (as measured by ear swelling) to oxazolone when administered i.p. to BALB/c mice at doses of 1, 10, 50 or 100 mg/kg beginning 3 days before oxazolone sensitization and continuing until hapten challenge 5 days later. In contrast, sex and age matched controls receiving 200 mg hydrocortisone/kg i.p. beginning on the day of oxazolone sensitization and continuing to hapten challenge demonstrate a significant (P less than 0.001) abrogation of DTH.

Comparison of agar dilution, tube dilution, and broth microdilution susceptibility tests for determination of ramoplanin MICs.

Standard broth microdilution (with and without bovine serum albumin [BSA] supplementation), tube dilution, and agar dilution susceptibility tests were compared for determining ramoplanin MICs. With a data base of 246 clinical isolates of gram-positive bacteria from 33 U.S. sites, it was shown that (i) agar and tube dilution susceptibility tests gave essentially the same results (93.9% of the test results were within 1 doubling dilution of equivalence), (ii) broth microdilution susceptibility tests gave results up to 5 doubling dilutions higher than agar or tube assays, and (iii) this data skewing could be reversed by BSA supplementation (final concentration, 0.02%) of the broth microdilution test medium.

Particle size distribution of Serratia marcescens aerosols created during common laboratory procedures and simulated laboratory accidents.

Andersen air samplers were used to determine the particle size distribution of Serratia marcescens aerosols created during several common laboratory procedures and simulated laboratory accidents. Over 1,600 viable particles per cubic foot of air sampled were aerosolized during blending operations. More than 98% of these particles were less than 5 mu in size. In contrast, 80% of the viable particles aerosolized by handling lyophilized cultures were larger than 5 mu. Harvesting infected eggs, sonic treatment, centrifugation, mixing cultures, and dropping infectious material produced aerosols composed primarily of particles in the 1.0- to 7.5-mu size range.

beta-Lactam antibiotic modulation of murine neutrophil cytokinesis.

Fourteen cephalosporins, 11 penicillins and 1 monobactam were evaluated for their in vitro modulation of murine neutrophil cytokinesis. As a result, the beta-lactam antibiotics were placed into 6 groups based on their effect on random (R) and FMLP-directed (D) migration [Group 1 (no effect): cephalosporin C; Group 2 (R-->D decreases): cloxacillin, cefotaxime, ceftazadime, cefuroxime, cephalothin, cephapirin, cephadine, nafcillin, piperacillin, ticarcillin, ampicillin, oxacillin, aztreonam; Group 3 (R increases D-->): cephaloridine; Group 4 (R increases D increases): cefsulodin; Group 5 (R increases D decreases): cefoperazone, cefoxitin, ceftriaxone, 6-amino-penicillanic acid; Group 6 (R decreases D decreases): cefadroxil, cefazolin, penicillin G, methicillin]. Trypan blue exclusion studies showed that inhibition of R and D by Group 6 beta-lactam antibiotics is not due to overt cytotoxicity. beta-lactam antibiotics inhibiting D also increased neutrophil adherence to plastic at a concentration of 1000 microM. Finally, the [Ca++] inhibitor chlorpromazine significantly abrogates beta-lactam- and FMLP-directed migration at a test concentration of 1 microM.

Comparison of the agar dilution, tube dilution, and broth microdilution susceptibility tests for determination of teicoplanin MICs.

The purpose of this study was to evaluate the National Committee for Clinical Laboratory Standards agar dilution, tube dilution, and broth microdilution susceptibility tests for the measurement of teicoplanin MICs. The three standardized tests gave equivalent (within a twofold dilution) results with 98.8 to 99.0% of the 508 gram-positive clinical isolates tested, indicating that either method may be used for teicoplanin MIC determination.

Comparative effect of the naphthalenic ansamycins rifamycin SV, rifampin and cyclopentylrifampicin on murine neutrophil function.

The purpose of this study was to evaluate the in vitro effect of the naphthalenic ansamycins rifamycin SV, rifampin and cyclopentylrifampicin on neutrophil degranulation and cytokinesis using murine peritoneal exudate cells. It was found that the FMLP-stimulated secretion of myeloperoxidase was significantly inhibited by 80 micrograms rifamycin SV (P less than 0.05) and cyclopentylrifampicin (P less than 0.01) per ml. Nondirected and FMLP-directed migration was significantly (P less than 0.01) inhibited by rifamycin SV and rifampin at assay concentrations above 0.31 and 5.0 micrograms/ml respectively thus confirming the low dose rifamycin effect observed by others using human neutrophils. Finally, cyclopentylrifampicin was shown to have no significant effect on nondirected or FMLP-directed neutrophil migration at assay concentrations of 1.25 to 80 micrograms per ml.