Cytosolic mercaptopyruvate sulfurtransferase is evolutionarily related to mitochondrial rhodanese. Striking similarity in active site amino acid sequence and the increase in the mercaptopyruvate sulfurtransferase activity of rhodanese by site-directed mutagenesis

Rat liver mercaptopyruvate sulfurtransferase (MST) was purified to homogeneity. MST is very similar to rhodanese in physicochemical properties. Further, rhodanese cross-reacts with anti-MST antibody. Both purified authentic MST and expressed rhodanese possess MST and rhodanese activities, although the ratio of rhodanese to MST activity is low in MST and high in rhodanese. In order to compare the active site regions of MST and rhodanese, the primary structure of a possible active site region of MST was determined. The sequence showed 66% homology with that of rat liver rhodanese. An active site cysteine residue (Cys246; site of formation of persulfide in catalysis) and an arginine residue (Arg185; substrate binding site) in rhodanese were also conserved in MST. On the other hand, two other active site residues (Arg247 and Lys248) were replaced by Gly and Ser, respectively. Conversion of rhodanese to MST was tried by site-directed mutagenesis. After cloning of rat liver rhodanese, recombinant wild type and three mutants (Arg247-->Gly and/or Lys248-->Ser) were constructed. The enzymes were expressed in Escherichia coli strain BL21 (DE3) with a T7 promoter system. The mutation of these residues decreases rhodanese activity and increases MST activity.

Improved bactericidal activity of Q-35 against quinolone-resistant staphylococci

The bactericidal effects of Q-35, sparfloxacin, tosufloxacin, and ofloxacin on 18 strains of methicillin-resistant Staphylococcus aureus (MRSA) and 3 strains of Staphylococcus epidermidis were studied by a viable-count method. Staphylococci as used in this study were clearly divided into two groups with respect to their susceptibilities to sparfloxacin. MICs of Q-35 and tosufloxacin were 0.05 to 0.78 microgram/ml for sparfloxacin-susceptible strains (MICs, 0.05 to 0.2 microgram/ml) and 1.56 to 12.5 micrograms/ml for sparfloxacin-resistant strains (6.25 to 25 micrograms/ml). All the sparfloxacin-resistant strains of MRSA tested contained the gyrA mutation at codon 84. Time-kill studies showed that Q-35 decreased the viable counts from approximately 10(7) CFU/ml to 10(3) to 10(5) CFU/ml within 3 h at concentrations greater than the MICs against both sparfloxacin-susceptible and -resistant strains. In contrast, sparfloxacin, tosufloxacin, and ofloxacin produced bacteriostatic effects at 3 h after exposure against sparfloxacin-resistant strains at concentrations which were greater than the respective MICs, whereas these quinolones were bactericidal against sparfloxacin-susceptible strains. The rapid bactericidal activities of Q-35 against sparfloxacin-resistant MRSA were reduced when the methoxy group of Q-35 at the 8 position was substituted with fluorine or hydrogen. Thus, our data suggest that the introduction of a methoxy group into the 8 position of quinolones contributes to the bactericidal activities of fluoroquinolones against quinolone-resistant staphylococci.

Hepatocyte growth factor as a hematopoietic regulator

Hepatocyte growth factor (HGF) was originally isolated as a mitogen for adult hepatocytes, but this cytokine is now regarded as a multi-functional factor. In the present study, we show that the mouse liver in the middle and/or late stage of the fetal life expresses both HGF and c-met (its receptor) messages. HGF and c-met mRNA are coexpressed not only in the adherent layers of fetal liver long-term cultures (FL-LTCs) and adult bone marrow long-term cultures (BM-LTCs), but also in the stromal cell lines MS-5 and PA-6. Addition of human HGF (2 and 20 ng/mL) to the LTCs enhances (1) nonadherent cell counts (ninefold in FL-LTCs and sixfold in BM-LTCs), (2) nonadherent colony-forming unit-in culture (CFU-C) counts (eightfold in FL-LTCs and fivefold in BM-LTC), and (3) cobblestone colony counts. However, HGF slightly inhibits the proliferation of stromal cells. No direct effect of HGF on freshly isolated BM and/or FL cells is found in the CFU-C assay. However, an approximately 1.5-fold synergistic increase in CFU-C counts is noted when the BM or FL cells are cocultured with HGF in the presence of interleukin-3. These findings strongly suggest that HGF plays a crucial role as a hematopoietic regulator in the proliferation and differentiation of hematopoietic progenitors.

Ventilatory responses to inspiratory resistive loading before and after gastrectomy during isoflurane anesthesia

We tested the hypothesis that steady-state responses to inspiratory-flow-resistive loading would be preserved immediately after upper abdominal surgery in anesthetized patients. Twenty patients were studied immediately before and after gastrectomy under 1 minimum alveolar anesthetic concentration (MAC) of isoflurane anesthesia. Ventilation, airway occlusion pressure, and Paco2 were measured before and during inspiratory-flow-resistive breathing lasting from 6 to 7 min. Ten of 20 subjects were tested with resistance of 51.8 cm H2O.L-1.s-1 (Load 1) and the remaining 10 subjects were tested with resistance of 83.3 cm H2O.L-1.s-1 (Load 2). Ventilatory variables obtained immediately before and after surgery were compared in each group. Baseline ventilation increased postoperatively with greater frequency of breathing and comparable tidal volume (VT). Immediately after the application of resistive load, minute ventilation (VI) significantly decreased both pre- and postoperatively, due primarily to the decrease of VT. During sustained loading, VI gradually increased and reached steady state in 2-3 min. After 5 min of loading, Paco2 returned to the control level with Load 1 whereas with Load 2, it was higher than the control value. The magnitude and time course of reduced ventilation in response to resistive load were identical between pre- and postoperative conditions. We conclude that the ability of maintaining ventilation to imposed inspiratory-flow-resistive loading is well preserved during 1 MAC of isoflurane anesthesia before and after gastrectomy.

[Synergism of ciprofloxacin and roxithromycin to Pseudomonas aeruginosa biofilm]

Synergism of ciprofloxacin (CPFX) and roxithromycin (RXM) to bacterial biofilms formed by Pseudomonas aeruginosa was investigated. Measurement of antibacterial activities and morphological observation with a scanning electron-microscope suggested that RXM eradicated the biofilms by unknown mechanism and thereby enhanced the bactericidal activity of CPFX to P. aeruginosa in biofilms.

Mechanism of inhibition of xanthine oxidase with a new tight binding inhibitor

The mechanism of inhibition of milk xanthine oxidase and xanthine dehydrogenase by the tight binding inhibitor, sodium-8-(3-methoxy-4-phenylsulfinylphenyl)pyrazolo[1,5-a]-1,3,5- triazine-4-olate monohydrate (BOF-4272), was studied after separation of the two isomers. The steady state kinetics showed that the inhibition by these compounds was a mixed type. One of the isomers had a Ki value of 1.2 x 10(-9) M and a Ki' value of 9 x 10(-9) M, while the other isomer had a Ki value of 3 x 10(-7) M and a Ki' value of 9 x 10(-6) M. Spectral changes were not observed by mixing either the oxidized or reduced form of the enzyme with BOF-4272. The stopped-flow study and the effects of BOF-4272 on various substrates showed that BOF-4272 bound to the xanthine binding site of the enzyme. Kd values of the enzyme and one of the isomers, which has a higher affinity for the enzyme, were also found to be 2 x 10(-9) M for the active form of the enzyme and 7 x 10(-9) M for the desulfo-form using fluorometric titration, and the binding has stoichiometry of 1:1. The inhibitor could not bind to the enzyme when the enzyme was previously treated with oxipurinol.

Antibiotic susceptibility of the sputum pathogens and throat swab pathogens isolated from the patients undergoing treatment in twenty-one private clinics in Japan

Bacteriology of the respiratory isolates from 2,539 patients with respiratory infections in 21 primary care clinics was documented. Of a total of 1,887 strains of potential pathogens recovered from 1,507 patients, 996 were gram-positive and 891 were gram-negative. Major pathogens were Staphylococcus aureus, Haemophilus influenzae, Streptococcus pneumoniae and Streptococcus pyogenes. The MIC's against microbial isolates of six antimicrobial agents were determined. Ciprofloxacin and ofloxacin were more active against S. aureus, Moraxella catarrhalis and Pseudomonas aeruginosa, and ampicillin and cefteram were more active against S. pnuemoniae and S. pyogenes than four other antimicrobials tested, respectively, in this experiment. New quinolones and new generation cephems were active against H. influenzae and Enterobacteriaceae. Only one strain of S. aureus was methicillin-resistant. As regards other pathogens, 6.5% of S. pneumoniae and 14.9% of H. influenzae were resistant to ampicillin, and 26.7% of H. influenzae were beta-lactamase-positive. MRSA was found infrequently. But ampicillin-resistant S. pneumoniae and H. influenzae were found in primary care clinics almost as frequently as in intensive-medication-oriented clinics.

Successful bone marrow transplantation by bone grafts in chimeric-resistant combination

It has been shown that the bone marrow cells (BMCs) of DBA/2 mice do not readily take in bone marrow from C57BL/6 mice, even if more than 5 x 10(6) cells are injected. In this paper, we show that such chimerism resistance can be overcome by cografting DBA/2 bones from which the hematopoietic cells have been removed but in which the stromal cells remain. C57BL/6 mice reconstituted with BMCs plus bones of DBA/2 mice survive significantly longer than C57BL/6 mice reconstituted with DBA/2 BMC alone. In the former, not only the hematolymphoid cells but also the stromal cells are replaced by donor-type cells, whereas in the latter, the donor hematolymphoid cells are rejected. These findings indicate that the stromal cells in the engrafted bones play a crucial role in the prevention of graft rejection in bone marrow transplantation.

Role of cysteine 337 and cysteine 340 in flavoprotein that functions as NADH oxidase from Amphibacillus xylanus studied by site-directed mutagenesis

A flavoprotein from Amphibacillus xylanus catalyzes the reduction of oxygen to hydrogen peroxide. Each polypeptide chain in the tetrameric enzyme contains 5 cysteine residues. The complete reduction of enzyme by dithionite requires 6 electrons. Such behavior indicates the presence of redox centers in addition to the FAD, and these could be disulfides. In order to assess the catalytic role of disulfide in the enzyme, 2 of the cysteines (Cys-337 and Cys-340), which show a high degree of homology with alkyl hydroperoxide reductase F52a protein and thioredoxin reductase, have been changed to serines by site-directed mutagenesis of the cloned flavoprotein gene (individually and in a double mutant). Titration of the three mutant enzymes, lacking Cys-337, Cys-340, or both cysteines, requires only 2 electron eq to reach the reduced flavin state. These results indicate the absence of a redox-active disulfide and demonstrate the involvement of Cys-337 and Cys-340 in the redox-active disulfide. The catalytic activity of the three enzymes was examined by steady-state analysis. The Km for NADH and oxygen and the kcat value of these mutant enzymes were essentially the same as those of wild type. The NADH oxidase activities were also accelerated markedly in the presence of free FAD, which is the case for wild-type enzyme. The NADH:5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) oxidoreductase activities of all mutant enzymes were less than 3% of the activity of wild-type enzyme. The weak DTNB reductase activities in the mutant enzymes lacking Cys-337 or Cys-340 may occur through direct reduction of the mixed disulfide Cys-337-thiol or Cys-340-thiol and nitrothiobenzoate by FADH2. However, the weak DTNB reductase activity in the mutant enzyme lacking both cysteines indicates that FADH2 can reduce either DTNB or another disulfide directly, albeit inefficiently. These results suggest intramolecular dithiol-disulfide interchange reactions in the flavoprotein.

Cloning, expression, and characterization of cDNAs encoding Arabidopsis thaliana squalene synthase

We have isolated and characterized two overlapping cDNA clones for Arabidopsis thaliana squalene synthase. Their nucleotide sequences contained an open reading frame for a 410-amino acid polypeptide (calculated molecular mass, 47 kDa). The deduced amino acid sequence of the Arabidopsis polypeptide was significantly homologous (42-44% identical) to the sequences of known squalene synthases of several species, from yeast to man, but it was much less homologous to that of tomato phytoene synthase. To express the Arabidopsis enzyme in Escherichia coli, the entire coding region was subcloned into an expression vector. A cell-free extract of E. coli transformed with the recombinant plasmid, in the presence of NADPH and Mg2+, efficiently converted [14C]farnesyl diphosphate into squalene. On the other hand, in the absence of NADPH and the presence of Mn2+, the cell-free extract formed dehydrosqualene as a secondary product. Another E. coli extract expressing mouse squalene synthase showed the same activity as the Arabidopsis enzyme. Therefore, both the structure and reaction mechanism of squalene synthases are markedly conserved in taxonomically remote eukaryotes.

Immunohistochemical detection of advanced glycosylation end products within the vascular lesions and glomeruli in diabetic nephropathy

Numerous studies over the years have implicated advanced glycosylation end products (AGEs) in the pathogenesis of many of the complications of diabetes and normal aging. The recent development of specific antibodies against AGE-modified proteins has facilitated investigations on the formation and tissue distribution of AGEs. We used anti-AGE antibodies to localize AGEs within kidney specimens obtained from both diabetic and nondiabetic individuals. Immunohistochemical staining using anti-AGE antibody showed a high level of AGE accumulation in diabetic and aged vascular intima, particularly along the inner elastic layer of arteries. Positive staining also was observed within nodular and severe diffuse lesions of glomeruli as well as in hyaline deposits of arterioles. These data support a pathogenic role for advanced glycosylation in the renal complications of diabetes and aging.

nfxC-type quinolone resistance in a clinical isolate of Pseudomonas aeruginosa

Quinolone resistance gene nqr-T91 in a clinical isolate of Pseudomonas aeruginosa P1481 was cotransducible with catA1 in P. aeruginosa PAO. The nqr-T91 transductant, PKH-T91, was resistant to norfloxacin, imipenem, and chloramphenicol and showed less norfloxacin accumulation than the parent strain did. Loss of the 46-kDa outer membrane protein (D2) and an increase in the 50-kDa outer membrane protein in PKH-T91 were observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Lipopolysaccharides in the transductant were also changed. These alterations were considered to be related to lower levels of norfloxacin accumulation in PKH-T91. These genetic and biochemical properties suggested that an nfxC type of quinolone-resistant mutation occurred in a clinical isolate of P. aeruginosa P1481.

The structure of chicken liver xanthine dehydrogenase. cDNA cloning and the domain structure

The amino acid sequence of chicken liver xanthine dehydrogenase (EC 1.1.1.204) was determined by cDNA cloning and partial amino acid sequencing of the purified enzyme. The enzyme consisted of 1358 amino acids with calculated molecular mass of 149,633 Da. In order to compare the structure of the chicken and rat enzymes, limited proteolysis was performed with the purified chicken liver xanthine dehydrogenase. When the enzyme was digested with subtilisin, it was not converted from the NAD-dependent dehydrogenase type to the O2-dependent oxidase type, in contrast with the mammalian enzyme. However, the enzyme was cleaved mainly into three fragments in a manner similar to that for the rat enzyme at pH 8.2 (20, 37, and 84 kDa) and retaining a full complement of redox centers. The cleavage sites were identified by determination of amino-terminal sequences of the produced fragments. It was concluded that the 20-kDa fragment was amino-terminal, the 84-kDa fragment carboxyl-terminal, and the 37-kDa fragment an intermediate portion in the enzyme protein. On the other hand, when the enzyme was digested with the same protease at pH 10.5, the sample contained only the 20- and 84-kDa portions and lacked the 37-kDa portion. The resultant sample possessed xanthine dichlorophenol indophenol reductase activity, indicating that the molybdenum center remained intact. The absorption spectrum showed the sample was very similar to deflavo-enzyme. From these results and sequence analyses, the domain structure of the enzyme is discussed.

Mapping of the gene for human xanthine dehydrogenase (oxidase) (XDH) to band p23 of chromosome 2

Fluorescent in situ hybridization in combination with Q-banding revealed that the human xanthine dehydrogenase (XDH) gene is located on band p23 of chromosome 2.

Effects of alpha- and beta-arbutin on activity of tyrosinases from mushroom and mouse melanoma

The effects of alpha- and beta-arbutin on the activity of tyrosinases from mushroom and mouse melanoma were examined. alpha-Arbutin was synthesized from hydroquinone and starch using glucoside synthetase (GSase). beta-Arbutin inhibited both tyrosinase activities from mushroom and mouse melanoma. alpha-Arbutin inhibited only the tyrosinase from mouse melanoma, 10 times as strongly as beta-arbutin. The IC50 of alpha-arbutin was 0.48 mM and its inhibitory mechanism was speculated to be mixed type inhibition, while that of beta-arbutin was noncompetitive.

Purification and analysis of a flavoprotein functional as NADH oxidase from Amphibacillus xylanus overexpressed in Escherichia coli

The gene encoding the Amphibacillus xylanus flavoprotein has been cloned into pTTQ18 and overexpressed in Escherichia coli. The recombinant enzyme has been purified to homogeneity yielding 15 mg of pure enzyme/liter of cell culture. Recombinant flavoprotein is fully active and has an absorption spectrum identical to that of the enzyme purified from A. xylanus. The N-terminal sequence analysis and analytical gel filtration data confirm the structural identity of recombinant and A. xylanus enzymes. The Km value for oxygen and the Km value for NADH are 1.7 mM and 33.3 microM, respectively. In the presence of free additional FAD, however, the Km value for oxygen decrease dramatically. The NADH oxidase activity is accelerated markedly in the presence of additional FAD. The intracellular free FAD concentration of A. xylanus is calculated about 13 microM. This FAD concentration would be enough to accelerate the NADH oxidase activity of flavoprotein in cells of A. xylanus. Two-electron reduction of the enzyme FAD by the strong reductant dithionite occurs during the total uptake of 6 electrons. Such behavior usually indicates the presence of non-flavin redox centers. The high degree of homology between this enzyme and alkyl hydroperoxide reductase F52a protein and thioredoxin reductase suggests that these centers are the redox-active disulfide adjacent to the FAD and another disulfide, which is able to slowly interchange with the redox-active disulfide. The presence of two disulfides has been demonstrated.

Burkholderia (formerly Pseudomonas) cepacia porin is an oligomer composed of two component proteins

The 81 kDa protein (designated OpcPO) which forms a diffusion pore in the outer membrane of Burkholderia (formerly Pseudomonas) cepacia has a unique characteristic in that when the purified protein is heated it yields a major 36 kDa protein (designated OpcP1) and a minor 27 kDa protein (designated OpcP2). Moreover, incubation of OpcPO in citrate buffer at pH 3.0 produced an unusual dissociation into 72 kDa and 27 kDa proteins. For the characterization of OpcPO and its derivatives, OpcP1 and OpcP2 from purified OpcPO were isolated by preparative SDS-PAGE. Reconstitution of OpcPO using purified preparations of OpcP1 and OpcP2 indicated that these derivatives were not proteolytic fragments of OpcPO. Moreover, immunoblot assays with murine polyclonal antisera specific for OpcP1 and OpcP2 yielded the following results: (i) OpcP1 and OpcP2 are immunologically distinguishable proteins; (ii) the unusual dissociation of OpcPO in citrate buffer at pH 3.0 resulted in the release of OpcP2 from OpcPO, and the resulting 72 kDa protein was probably an oligomer of OpcP1; (iii) purified OpcP1 itself produced two additional 53 kDa and 72 kDa proteins spontaneously following elution from the bottom of the SDS-PAGE gel. From these findings, it was concluded that OpcPO is formed by the non-covalent association of OpcP2 with an oligomer of OpcP1 that has the ability to self-assemble.

Role of beta-lactamase of methicillin-susceptible Staphylococcus aureus in resistance to first-generation oral cephems both in vitro and in vivo

Cefaclor, among the oral cephalosporins tested, showed the largest inoculum effect with respect to MIC values for 61 clinical isolates of methicillin-susceptible Staphylococcus aureus, including 39 beta-lactamase producing strains. These 39 strains were divided into eight type A, 29 type B or C, and two type D producers, by comparisons of specific activities to three substrates. Two producers, one each of types A and C, were further studied to investigate the effect of beta-lactamase on staphylococcal resistance to several beta-lactams. Concentrations of cefaclor and cephalexin in cultures of these strains decreased rapidly, whereas hydrolysis of these drugs by the purified beta-lactamases was moderate to low as detected by spectrophotometric assay. Cefaclor showed high affinities for penicillin-binding proteins 1, 2, and 3 of both beta-lactamase producers and their respective penicillinase-non-producing mutants. In experimental intraperitoneal infections in mice, cefaclor was therapeutically effective against both mutants, showing 50% effective doses of less than 10 mg/kg/dose. In contrast, it was not satisfactory against the parent strains, requiring greater-than-10-fold increases in concentration for the same degree of survival. We concluded that resistance to first-generation oral cephems seen both in vitro and in vivo was due mainly to the beta-lactamase production.

Levels of hepatocyte growth factor in synovial fluid and serum of patients with rheumatoid arthritis and release of hepatocyte growth factor by rheumatoid synovial fluid cells

OBJECTIVE

To determine the levels of hepatocyte growth factor (HGF) in synovial fluids (SF) and sera from patients with rheumatoid arthritis (RA); to examine how these correlate with several disease variables in patients with RA and with levels of interleukin-6 (IL-6) in SF of these patients; and to examine whether HGF is released from adherent synovial cells (ASC) and synovial fluid cells (SF cells).

METHODS

An enzyme linked immunosorbent assay was used to measure levels of HGF and IL-6. SF samples were obtained from 22 patients with RA, 12 with osteoarthritis (OA), and one with septic arthritis. Serum samples were collected from 40 patients with RA. HGF levels in culture supernatants from ASC and SF cells were measured.

RESULTS

The mean values of HGF in SF were 1.21 ng/ml for patients with RA, 0.19 ng/ml for those with OA and 0.18 ng/ml for the one with septic arthritis. HGF levels in SF of patients with RA were significantly higher than of those with OA (p < 0.01). The levels for patients with RA correlated with the serum C-reactive protein concentrations (r = 0.626, p < 0.01) and IL-6 levels in SF (r = 0.476, p < 0.05). The mean value of HGF in sera from patients with RA was 0.28 ng/ml. HGF levels in SF were higher than those in sera drawn simultaneously from the same patients with RA. In vitro, release of HGF from rheumatoid ASC was not detected. However, SF cells from patients with RA released HGF spontaneously.

CONCLUSION

Our observations suggest that HGF in SF of patients with RA is produced by SF cells and is related to disease activity of RA, and thus that HGF may play a role in RA.

Effects of surgical stimulation on the apnoeic thresholds for carbon dioxide during anaesthesia with sevoflurane

Mechanical hyperventilation may produce hypocapnic apnoea below the carbon dioxide off-switch threshold whereas an increase in arterial PCO2 after post-hyperventilation apnoea causes reappearance of respiratory effort above the carbon dioxide on-switch threshold. To study the effects of surgical stimulation on these two thresholds, we have measured end-tidal PCO2 (PE'CO2) at the two thresholds, before and during surgical stimulation, in 14 patients undergoing mastectomy, anaesthetized with sevoflurane (1.2 MAC). Based on the reproducibility of the results, data from 11 patients were analysed and data from the three other patients were discarded. Before surgical stimulation, mean resting PE'CO2' off-switch threshold and on-switch threshold were 5.7 (SEM 0.2), 5.2 (0.2) and 6.1 (0.2) kPa, respectively. The off-switch threshold was significantly less than resting PE'CO2 (P < 0.01) but the on-switch threshold was significantly greater than resting PE'CO2 (P < 0.01). During surgical stimulation, resting PE'CO2' off-switch threshold and on-switch threshold were 4.8 (0.2), 4.1 (0.2) and 4.7 (0.2) kPa, respectively. Although the off-switch threshold was significantly less than resting PE'CO2 (P < 0.01), there were no significant differences between resting PE'CO2 and on-switch threshold. These results indicate that surgical stimulation does not affect equally the carbon dioxide on- and off-switch thresholds.

[Studies on respiratory infections in primary care clinic (V). The pattern of distribution on bacteria, Mycoplasma pneumoniae and virus isolated from patients with respiratory infections, who were seen in six private clinics, and clinical efficacy of ciprofloxacin and roxithromycin]

The pattern of distribution of bacteria, Mycoplasma pneumoniae and virus isolated from the same specimen recovered from the throat swab or the sputum of 479 patients with respiratory infections who were seen in six private clinics in Sendai City of Japan during the period from October to November in 1992 (period I) and from January to February in 1993 (period II) was documented. Of the 479 patients, 234 had acute pharyngitis, 145 had acute bronchitis, 96 had influenza, 21 had acute tonsillitis, 5 had acute pneumonia and 9 had other respiratory infections. One hundred (42.4%) strains of potential pathogen and one strain of M. pneumoniae were recovered from 236 cases in period I, and 66 (27.2%) strains of potential pathogen, one strain of M. pneumonae and 73 strains of Influenza virus (30.0%: 43 of type A Hong-Kong and 30 of type B) from 243 cases in period II. Of the 166 strains, major isolates were Staphylococcus aureus (56 strains), Streptococcus pneumoniae (12 strains), Streptococcus pyogenes (15 strains), Haemophilus influenzae (17 strains), Esherichia coli (4 strains), Klebsiella spp. (35 strains), Pseudomonas aeruginosa (4 strains) and Acinetobacter spp. (23 strains). Only one strain of S. aureus was resistant to methicillin (MIC: 50 micrograms/ml). None of S. pneumoniae was resistant to 1 microgram/ml of ampicillin. Ciprofloxacin was administered to 113 cases and roxythromycin to 220 cases by doctors in charge.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation of OprM-deficient mutants of Pseudomonas aeruginosa by transposon insertion mutagenesis: evidence of involvement in multiple antibiotic resistance

Overproduction of the Pseudomonas aeruginosa outer membrane protein OprM was observed in the nalidixix acid (NalB-type) multidrug-resistant strains. To clarify the involvement of OprM in the resistance, transposon mutants were isolated from strain PAO4141 and its OprM-overexpressed mutant KG2113 and were screened for OprM production by immunoblot assays using murine polyclonal antiserum resulting from immunization with purified OprM. Two OprM-deficient mutants from PAO4141 and one from KG2113 were identified. Determination of the susceptibilities of these mutants to antimicrobial agents demonstrated that OprM was involved not only in the acquired resistance, but also in the intrinsic resistance of P. aeruginosa to quinolones, cephems, penicillins, tetracycline, and chloramphenicol.