Pyridonecarboxylic acids as antibacterial agents. IX. Synthesis and structure-activity relationship of 3-substituted 10-(1-aminocyclopropyl)-9-fluoro-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de]- 1,4-benzoxazine-6-carboxylic acids and their 1-thio and 1-aza analogues.

A series of the title compounds listed in Chart 1 have been synthesized to study the effects of 3-alkyl substituents on the antibacterial potency and in vivo efficacy of 10-(1-aminocyclopropyl)-9-fluoro-7-oxo-2,3-dihydro-7H-pyrido[1,2,3 -de]-1,4-benzoxazine-6-carboxylic acid and its 1-thio and 1-aza variants. Compound (S)-1, which proved most active in vitro against five representative gram-positive and gram-negative organisms, was assayed in vivo using Staphylococcus aureus and Pseudomonas aeruginosa mouse infection models. It exhibited an excellent in vivo efficacy, being superior to ofloxacin and ciprofloxacin, and was then assayed for convulsion-inducing activity, mammalian cell cytotoxicity, and topoisomerase II inhibition. The biological results showed that (S)-1 displayed antibacterial and toxicological advantages over ofloxacin and ciprofloxacin. Compound (S)-1 and its methanesulfonate showed high serum concentrations after oral and intravenous administrations to mice.

Pyridonecarboxylic acids as antibacterial agents. VI. Synthesis and structure-activity relationship of 7-(alkyl, cycloalkyl, and vinyl)-1-cyclopropyl-6-fluoro-4-quinolone-3-carboxylic acids.

The title compounds (1a-i) have been synthesized starting with ethyl 1-cyclopropyl-6,7-difluoro-4-quinolone-3-carboxylate (2). The 7-cyclopropyl and 7-vinyl derivative (1e and 1i) exhibited potent in vitro antibacterial activities against both gram-positive and gram-negative bacteria, being equipotent with ciprofloxacin (CPFX) except for the activity against Pseudomonas aeruginosa. The two compounds were significantly less toxic than CPFX in terms of convulsion-induction as determined by intracerebral administration to mice, but showed lower urinary recoveries on intravenous administration.

Pyridonecarboxylic acids as antibacterial agents. VII. Synthesis and structure-activity relationship of amino- and hydroxyl-substituted 7-cycloalkyl and 7-vinyl derivatives of 1-cyclopropyl-6-fluoro-4-quinolone-3- carboxylic acid.

Novel C(7)-derivatives of 1-cyclopropyl-6-fluoro-4-quinolone carboxylic acid (3a-o) have been synthesized and evaluated for in vitro antibacterial activity. Compounds 3e (3-aminocyclobutyl), 3g (1-aminocyclopropyl), 3m ((2-aminomethyl)vinyl), and 3o ((1-aminomethyl)vinyl) showed significant inhibitory activity, comparable to that of ciprofloxacin, against gram-negative bacteria including P. aeruginosa. A good pharmacokinetic profile (serum and brain concentrations and urinary recovery) was obtained for the two cyclic compounds (3e and 3g), but that of the vinylic compounds (3m and 3o) was less favorable. Compound 3g was less toxic than 3e, ciprofloxacin, or ofloxacin in terms of acute toxicity and convulsion-induction.

Pyridonecarboxylic acids as antibacterial agents. VIII. Synthesis and structure-activity relationship of 7-(1-aminocyclopropyl)-4-oxo-1,8-naphthyridine-3-carboxylic acids and 7-(1-aminocyclopropyl)-4-oxoquinoline-3-carboxylic acids.

4-Oxo-1,8-naphthyridine- and 4-oxoquinoline-3-carboxylic acids (2a, b and 3a-1) possessing a 1-amino-cyclopropyl group at the 7-position have been synthesized and evaluated for in vitro antibacterial activities. The three quinolones (3d, h, i) exhibited potent antibacterial activities against both gram-positive and gram-negative bacteria, which are comparable to those of ciprofloxacin (CPFX) and ofloxacin (OFLX). Among the three compounds, the best pharmacological and pharmacokinetic profile was obtained with 3i, an OFLX analogue, which was considerably less toxic than three reference quinolones (1, CPFX and OFLX).

[Recombinant human erythropoietin (KRN5702) therapy for autologous blood transfusion in patients with rheumatoid arthritis undergoing joint replacement surgery--a multicenter phase II clinical trial].

In order to evaluate the effect of recombinant human erythropoietin (rHuEPO) on autologous blood transfusion in patients with rheumatoid arthritis (RA), we performed a phase II clinical trial in 65 RA patients undergoing elective surgery. rHuEPO was administered subcutaneously once a week and after observing erythropoiesis, autologous blood was collected. Fifty-seven of the 58 patients who completed treatment responded to rHuEPO and could donate more than 400 ml of autologous blood. Among them, 23 out of 28 patients undergoing total hip arthroplasty, 27 out of 28 undergoing total knee arthroplasty and 1 out of 1 undergoing spinal surgery did not need homologous blood transfusion perioperatively. During rHuEPO treatment, no significant changes of clinical parameters of RA activity were observed. Two patients discontinued the treatment because of mild and transient side effects. These results indicate that subcutaneous rHuEPO is safe and effective in eliminate the need for homologous blood transfusion, even in anemic RA patients undergoing elective orthopedic surgery.

High-density proteoglycan induces specific suppression of adjuvant-induced arthritis in rats.

In vitro data support the view that T cells in adjuvant-induced arthritis (AIA) respond to the proteoglycan (PG) component of articular cartilage; however, an in vivo role for PG in AIA has yet to be shown. To do so, we examined the effects of pretreatment with bovine cartilage high density PG (HDPG) on AIA induced by heat-killed Mycobacterium butyricum in Lewis rats. Purified bovine cartilage HDPG emulsified in Freund's incomplete adjuvant (FIA) was injected intradermally into rats 7 days before challenge with Myco. butyricum. The severity of arthritis was significantly suppressed in rats pretreated with as little as 0.75 mg of HDPG, and the arthritis was completely suppressed in rats pretreated with 3.0 mg of HDPG. This suppression was specific, as the same treatment did not protect against type II collagen-induced arthritis. Suppression of AIA is primarily a property of the HDPG, as suppression of the arthritis was significantly less with pretreatment with 3.0 mg of middle density fractions of PG, and no suppression was observed with pretreatment with the lowest density fraction of PG. Thus we report that pretreatment with cartilage HDPG, but not lower density PG, can induce specific suppression of AIA. These in vivo results support the view that immunity to cartilage HDPG plays a major role in the pathogenesis of AIA, and can induce specific tolerance to this type of arthritis.

Exacerbation of established collagen-induced arthritis in mice treated with an anti-T cell receptor antibody.

OBJECTIVE: To investigate the effect of T cell depletion on established collagen-induced arthritis (CIA) in mice, using monoclonal antibodies (MAb) to T cell receptor alpha/beta (TCR alpha/beta). In addition, experiments using anti-CD3 MAb were performed for comparison. METHODS: CIA was induced in male DBA/1 mice by immunizing them twice with bovine type II collagen (CII). The arthritis score and anti-CII antibody titers were examined serially. Proportions of T cells were determined by fluorescence-activated cell sorter (FACS) analysis on spleen cells or peripheral blood cells. RESULTS: When anti-TCR alpha/beta MAb was injected on the day of CII priming, no arthritis was detected in association with depressed anti-CII antibody titers. Unexpectedly, however, when MAb was given after arthritis was established, a rapid exacerbation of arthritis was observed, which resulted in ankylosis of most joints. Anti-CII antibody titers were not affected. The addition of anti-TCR gamma/delta MAb had no effect on the augmented arthritis. T cell depletion by anti-CD3 MAb during established CIA also caused an enhancement of arthritis, which was, however, weak and only transient. FACS analysis revealed that the early improvement of arthritis after the transient augmentation seen in the mice treated with anti-CD3 MAb paralleled the early recovery of alpha/beta T cells in the periphery. CONCLUSION: The present results support the concept that alpha/beta T cells, in general, may play a regulatory role in the clinical course of murine CIA after disease onset. Therefore, caution is recommended when using intensive T cell-targeted therapy in patients with rheumatoid arthritis.

Autologous blood transfusion with recombinant erythropoietin treatment. 22 arthroplasties for rheumatoid arthritis.

12 anemic and 10 non-anemic patients with rheumatoid arthritis were treated with recombinant human erythropoietin (rHuEPO) before arthroplasty. The patients received 400-800 units/kg of rHuEPO subcutaneously once a week. Autologous blood was collected after the hemoglobin concentration was increased by 5 percent or more. All but one of the patients responded to the treatment. They were given 1-3 units of autologous blood, and underwent the operation without homologous blood transfusion. The mean duration of the treatment was 1 month. In 1 patient with severe anemia, additional transfusion with 2 units of blood was necessary during the operation. In all patients, there was a tendency for the hemoglobin response ratio to rHuEPO to correlate negatively with the initial CRP levels. The treatment did not affect the patients' clinical rheumatologic condition and there were no adverse effects. These results demonstrated that the treatment with subcutaneous rHuEPO is both effective and non-toxic and can therefore eliminate the need for homologous blood transfusion in anemic patients undergoing arthroplasty for rheumatoid arthritis.

The effects of recombinant human granulocyte colony-stimulating factor on passive collagen-induced arthritis transferred with anti-type II collagen antibody.

Type II collagen-induced arthritis (CIA) is a pathologic process mediated, in part, by humoral immune mechanisms. Because many antibody-mediated reactions are neutrophil-dependent, the role of this cell population was examined in passive CIA transferred with anti-type II collagen (CII) antibody. In cyclophosphamide (CY)-induced leukocytopenic rats, swelling and inflammation associated with the arthritic response were significantly reduced. Concomitant administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF) to leukocytopenic rats for 7 consecutive days from the day of CY injection resulted in the recovery of peripheral blood neutrophils count and the abrogation of the suppression of arthritis with an optimal dose of anti-CII antibody. Further study demonstrated that a prior administration of rhG-CSF to naive rats for five consecutive days resulted in the significant and specific increase of peripheral blood neutrophils count and enhancement of passive arthritis with a suboptimal dose of anti-CII antibody. It was suggested that neutrophils played an important role in the development of passive CIA.

[Studies on the sub-MIC of beta-lactam antibiotics--bactericidal activity in compromised host's serum].

Bactericidal activity in compromised host's serum i.e. patients with cancer, the elderly, diabetes, was stronger than that in normal serum against Proteus mirabilis (P. mirabilis) but was weaker against Klebsiella pneumoniae (K. pneumoniae). Against Escherichia coli (E. coli), bactericidal activity on serum of patients with cancer was weaker in the following order, that in elderly serum, that in diabetic serum. Against Proteus vulgaris (P. vulgaris), bactericidal activity in elderly serum was similar to that in normal serum but was stronger than that in serum of patients with cancer. Against Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus), bactericidal activity in elderly serum and diabetic serum was similar to that in normal serum but was weaker than that in serum of patients with cancer. Piperacillin showed bactericidal activity in nutrient broth, normal serum and compromised host's serum at a concentration of 1/4 MIC against E. coli, P. mirabilis and P. aeruginosa. Aspoxicillin showed bactericidal activity in nutrient broth, and bactericidal or bacteriostatic activity in normal serum and serum of patients with cancer against E. coli and P. aeruginosa. While cefazolin and cefmetazole slightly inhibited the growth of bacteria in nutrient broth, they showed hardly any bactericidal activity in normal serum and compromised host's serum.

[Detection of inducible beta-lactamase in sputum--clinical studies on Pseudomonas respiratory infection].

To investigate the clinical incidence of inducible beta-lactamase, we measured the beta-lactamase activity in the sputum of 5 patients with chronic respiratory tract infection due to P. aeruginosa, by using the spectrophotometric method. During the piperacillin (PIPC) therapy given twice a day with a single dose of 2-3 g, sputum samples were collected every 2 hours for 3 days, and on the second day, two grams of Cefmetazole (CMZ) was added to PIPC therapy. The antibiotics concentration of each collected sputum samples were also measured by HPLC. In one out of 5 patients, no beta-lactamase activity in sputum was detected throughout the 3 days. However in three out of 5 patients, after the addition of CMZ to PIPC, the beta-lactamase activity significantly increased 2-3 times (max: 0.03 units/ml) that on PIPC alone, and gradually decreased on the 3rd day when PIPC was given alone. Then the peak concentration of PIPC with the addition of CMZ decreased to 38-73%, compared with that of PIPC alone. These findings were supported by the fact that CMZ showed a high in vitro inducer activity against the isolates from the sputum. In the remaining one patient, high beta-lactamase activity (mean: 0.16 units/ml) and no antibiotics concentration was detected to be constant throughout the 3 days, and it was confirmed for the reason that one of the isolates constitutively produced large amounts of beta-lactamase. These results suggest that inducible and constitutive beta-lactamase would clinically cause undesirable effects in the treatment by some beta-lactams and have a possibility of indirect pathogenesis.

Structure activity relationships in PIPC-analogues against Pseudomonas aeruginosa.

The relationship between the chemical structure and mode of action of piperacillin-analogues (PIPC-analogues) against Pseudomonas aeruginosa was investigated. The antibacterial activities of PIPC-analogues became stronger as the chain length of the alkyl group on the N-4 position in 2,3-dioxopiperazine when tested in constitutively beta-lactamase-producing strain, but not paralleled in wild and beta-lactamase-less strains. The outer membrane permeability was hardly affected by the chain length of the alkyl group at the N-4 position. The stability to beta-lactamase was stronger with the increase of the number of the carbon atoms of N-4 position. In the binding-affinities to the lethal penicillin-binding proteins (PBPs), compounds PIPC (C-2), C-3 and C-4 showed lower ID50 values than compounds C-1, C-6 and C-8. These results suggested that the stability to beta-lactamase was the governing part for the antibacterial activity in constitutively beta-lactamase-producing strain, and the binding affinity to lethal PBPs directly contributed to the antibacterial activity in wild and beta-lactamase-less strains.

Protective effect of piperacillin against the nephrotoxicity of cisplatin in rats.

The protective effect of piperacillin against the nephrotoxicity of cisplatin was compared with that of fosfomycin in Fischer 344 rats. Blood urea nitrogen, serum creatinine, and morphological changes were evaluated as the renal toxicological parameters. Rats receiving 2 mg of cisplatin per kg of body weight for 5 days showed significant (P less than 0.01 by multiple-comparison test) elevation of blood urea nitrogen and serum creatinine concentrations compared with rats receiving saline alone and also exhibited development of cell lesions in the pars recta of the tubules in the outer stripe of the outer medulla. However, piperacillin (250 and 1,000 mg/kg) significantly (P less than 0.01 by multiple-comparison test) reduced these toxicological parameters in comparison with results for cisplatin alone. The protective effect of piperacillin was superior to that of fosfomycin, although platinum levels in the kidney were higher with the combination of cisplatin and piperacillin than with cisplatin plus fosfomycin. Although the nephrotoxicity of cisplatin was also reduced when cisplatin was administered concomitantly with sodium chloride in mole-equivalents to 250 and 1,000 mg of piperacillin per kg, its protective effect was less than that of the corresponding piperacillin dose. These results suggest that piperacillin may have a role as a protective agent against the nephrotoxicity of cisplatin.

Mechanism of action of cephalosporins and resistance caused by decreased affinity for penicillin-binding proteins in Bacteroides fragilis.

The susceptibilities of 52 clinical isolates of Bacteroides fragilis to five monoanionic cephalosporins were examined. Cefoperazone showed the highest antibacterial activity, followed by ceftezole, cefazolin, cefamandole, and cephalothin. There were two groups of resistant strains: one group (ca. 15%), of which B. fragilis G-232 was a typical sample, was resistant to ceftezole (MIC, 100 micrograms/ml), cefazolin (MIC, 100 micrograms/ml), and cephalothin (MIC, 200 micrograms/ml) but not cefoperazone (MIC, 6.25 micrograms/ml) or cefamandole (MIC, 25 micrograms/ml). On the basis of studies of stability to beta-lactamase, outer membrane permeation, and affinity for penicillin-binding proteins (PBPs), we conclude that decreased affinity for PBP 3 may play an important role in the resistance to ceftezole, cefazolin, and cephalothin in B. fragilis G-232. Another group (also ca. 15%), of which B. fragilis G-242 was a representative, was resistant to all five cephalosporins (MIC, 100 to 400 micrograms/ml) and produced a high amount of beta-lactamase. Similar broad-spectrum resistance was seen in a mutant of strain G-232 that had a greater-than-30-fold increase in beta-lactamase production.

Outer membrane permeation of Bacteroides fragilis by cephalosporins.

Outer membrane permeation of Bacteroides fragilis by cephalosporins was examined by a previously described method. The permeation parameters of cephalosporins in B. fragilis were close to 10(-5) cm3/min per microgram of cell dry weight. These values were about an order of magnitude lower than those in Escherichia coli. In B. fragilis, the permeation was not directly proportional to the hydrophilicity of cephalosporins, and the ion selectivity was weak.

In vitro and in vivo antibacterial activities of T-3262, a new fluoroquinolone.

T-3262, a new fluoroquinolone, showed a broad spectrum of activity against gram-positive and gram-negative bacteria. T-3262 had most potent activity against gram-positive cocci, such as Staphylococcus, Streptococcus, and Enterococcus spp. The MICs of T-3262 for 90% of strains tested were between 0.05 and 1.56 micrograms/ml. Against members of the family Enterobacteriaceae and Pseudomonas aeruginosa, the activities of T-3262 were almost equal to those of ciprofloxacin. Obligate anaerobes were also susceptible to T-3262. T-3262 was bactericidal for one strain each of Staphylococcus aureus, Escherichia coli, and P. aeruginosa at concentrations near its MIC; and fluoroquinolones, including T-3262, inhibited DNA gyrase activity at low concentrations. The 50% effective dose of T-3262 after oral administration against systemic infections with S. aureus in mice was about 6 times lower than that of ofloxacin and about 20 times lower than that of norfloxacin.

Protective effect of piperacillin against nephrotoxicity of cephaloridine and gentamicin in animals.

The protective effect of piperacillin against the nephrotoxicity of cephaloridine and gentamicin was examined in experimental animals. In rabbits, piperacillin was infused at a dose of 1 mg/kg (body weight) per min over 225 min and cephaloridine (300 mg/kg) was intravenously administered as a bolus 45 min after the start of a drip infusion. Blood urea nitrogen, serum creatinine, and N-acetyl-beta-D-glucosaminidase (NAG) in urine were measured as the renal toxicological parameters before and 24 h after cephaloridine dosing. Although the single administration of cephaloridine significantly elevated these parameters, the elevation was prevented by the concomitant administration of piperacillin. The protective effect of piperacillin was superior to those of cephalothin and fosfomycin. In rats, piperacillin (1,000 mg/kg) was intravenously administered and immediately followed by the intramuscular administration of gentamicin (100 mg/kg) every 24 h for 5 days. When piperacillin was concomitantly administered with gentamicin, the elevations of blood urea nitrogen, serum creatinine, and urinary NAG were significantly lower than when gentamicin was given alone. The concomitant administration of piperacillin resulted in a significant protective effect against the nephrotoxicity of cephaloridine in rabbits and of gentamicin in rats. Histopathological observation also supported the protective effect of piperacillin. The protective mechanism of piperacillin might be the inhibition of transport from the peritubular side to tubular cells for cephaloridine and from both the peritubular and luminal sides for gentamicin.

The mechanism of action of piperacillin-analogues in vitro; effect of the carbon number at the N-4 position of 2,3-dioxopiperazine on the outer membrane permeability, stability to beta-lactamase and binding affinity to penicillin-binding proteins.

The relationship between the chemical structure and the mode of action of piperacillin-analogues (PIPC-analogues) against Escherichia coli and Klebsiella pneumoniae were investigated. The antibacterial activity of PIPC-analogues increased with an increase in the number of carbon atoms at the N-4 position of 2,3-dioxopiperazine. Their mode of action is discussed on the basis of the results of studies on outer membrane permeability, stability to beta-lactamase and binding affinity to penicillin-binding proteins (PBPs). The outer membrane permeability and stability to beta-lactamase were hardly affected by the chain length of the alkyl group at the N-4 position. On the other hand, the affinity to PBPs, especially to PBP 3, became stronger with increase of the number of carbon atoms at N-4 position. These results suggest that increased affinity to PBPs is the main reason for the increased antibacterial activity of the PIPC-analogues reported here.

Interactions of antimicrobial agents and antineoplastic agents.

The in-vitro interactions of four antimicrobial agents (piperacillin, dibekacin, minocycline, norfloxacin) and four antineoplastic agents (mitomycin C, bleomycin, doxorubicin, 5-fluorouracil) were examined by the chequerboard dilution method using 108 clinical isolates of four species of Gram-negative bacilli. Among the antimicrobial agents, piperacillin showed the greatest degree of synergism and norfloxacin the least. The frequency of synergism was essentially similar among the antineoplastic agents, although 5-fluorouracil was more frequently synergistic than other antineoplastic agents against Pseudomonas aeruginosa. Among the four species, synergism was most frequently shown against Proteus vulgaris and least against Escherichia coli. Antagonism was rarely seen.