A novel penicillin-binding protein, PBP-2' (Mr about 75,000), is known to be induced in excessively large amount by most beta-lactam compounds in cells of a clinically isolated strain of Staphylococcus aureus, TK784, that is highly resistant to beta-lactams and also most other antibiotics. This protein has very low affinities to most beta-lactam compounds and has been supposed to be the cause of the resistance of the cells to beta-lactams. A 14-kilobase DNA fragment was isolated from the cells that carried the gene encoding this penicillin-binding protein and also a genetically linked marker that is responsible for the resistance to tobramycin. This DNA was cloned on plasmid pACYC184 and was shown to cause both production of PBP-2' and resistance to tobramycin in Escherichia coli cells. However, the formation of PBP-2' in E. coli was only moderate and was independent of normal inducer beta-lactams. The PBP-2' formed in the E. coli cells showed slow kinetics of binding to beta-lactams similar to that of PBP-2' formed in the original S. aureus cells and gave a similar pattern of peptides to the latter when digested with the proteolytic V8 enzyme of S. aureus.

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The acidification of aqueous solutions containing Na2MoO4·2H2O in the presence of a chiral lysine ligand (d- and l-form) gives octamolybdates coordinating two lysine ligands, Na2[Mo8O26(d-lysH2)2]·8H2O (Mo8-d) and Na2[Mo8O26(l-lysH2)2]·8H2O (Mo8-l) (where lysH2 is 2,6-diammoniohexanoato), respectively. These two compounds crystallize with triclinic symmetry in the space group P1, the cell parameters being a = 10.782(2), b = 11.241(5), c = 10.027(2) Å, α = 93.21(2), β = 102.86(2), γ = 112.98(2)°, V = 1077(1) Å3, and Z = 1 for the Mo8-d, and a = 10.783(4), b = 11.246(3), c = 10.019(4) Å, α = 93.21(3), β = 102.75(3), γ = 112.98(2)°, V = 1077(2) Å3, and Z = 1 for Mo8-l. The X-ray crystal structures of these two species have been solved by the MITHRIL direct method and refined to R = 0.0337 and 0.0312 for Mo8-d and -l, respectively. The chiral lysine ligands are coordinated via their carboxylate-oxygen atoms at the vacant sites on the two five-coordinate molybdenum for the centrosymmetric γ-[Mo8O26]4− anion to retain their configuration with a resultant formation of optically-active octamolybdate species.

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Norfloxacin-and ciprofloxacin-resistant mutants of several Enterobacter cloacae and Serratia marcescens isolates occurred at frequencies of -10-7/CFU, which were higher than those of Escherichia coli isolates, in accordance with the increasing emergence of less-susceptible or resistant strains in clinical isolates of E. cloacae and S. marcescens. There has been continued interest in the development of fluoroquinolones, some of which have much greater in vitro activity and broader spectra than nalidixic acid (14). The emergence of resistance can significantly shorten the useful lifetime of antimicrobial agents (11), and resistance to nalidixic acid and the fluoroquinolones is the result of chromosomal mutations. To date, only two mechanisms of resistance to quinolones have been identified, mutation in the target enzyme DNA gyrase and mutations which appear to decrease drug permeation (1,(6)(7)(8). If frequencies of mutants resistant to fluoroquinolones were conspicuously low among members of the family Enterobacteriaceae (3, 10), the emergence of clinical isolates resistant to fluoroquinolones would be low. On the other hand, Sanders et al. (12) reported that several strains of Enterobacter cloacae and Serratia marcescens acquired resistance to fluoroquinolones at higher frequencies than did Escherichia coli. In this study, we determined the percentages of isolates that were resistant or less susceptible to quinolones and the frequencies of mutants resistant to the agents among E. coli, E. cloacae, and S. marcescens, as representative species.Totals of 108 strains of E. coli, 104 strains of E. cloacae, and 121 strains of S. marcescens were tested for quinolone susceptibility. These clinical isolates were collected from several hospitals throughout Japan between 1985 and 1986. Most of the E. coli and S. marcescens isolates originated from upper urinary tract infections, while those of E. cloacae were from sputum. Some of the patients involved had been treated with fluoroquinolones.Antibacterial susceptibility was measured by an agar dilution method using sensitivity disk agar (Nissui Seiyaku). MICs were determined after incubation at 37°C for 18 h.Spontaneous mutants resistant to quinolones were detected by plating a 0.1-ml sample of an overnight culture (inoculum, approximately 109 CFU/ml) onto sensitivity disk agar plates containing each drug at a concentration of four and eight times the MIC. After 48 h of incubation at 37°C, the CFU was determined, and the frequency of spontaneous mutants resistant to each drug was calculated.The apparent uptake of norfloxacin by intact cells was measured by the method of Hirai et al. (7), except as follows. The final elution was performed with 1 ml of 5% acetic acid solution, and the concentrations of samples were measured * Corresponding author.by high-performance liquid chromatography with a YMC-A312 column (YMC Co., Ltd.) at 270 nm by using a mobile phase consisting of 5% acetic acid-methanol (85:15, vol/vol). The experiments were performed in duplicate. Figure 1 shows...

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Monitoring of blood glucose content is vital for diabetes patients. The conventional widely used method involves an invasive procedure for blood sampling. In addition, blood glucose measured by this way is affected by immediate food consumption and it does not show accurate baseline blood glucose measurement. Thus, monitoring blood glucose by a noninvasive method that accurately reflects baseline blood glucose content is important. Glycated albumin (GA), a biomarker for diabetes indicating the average blood glucose over 2 weeks, can be used for semilong-term blood glucose monitoring. Detection of GA in saliva is a noninvasive method that alleviates the use of needles for diabetic patients; however, its content in saliva is in the nanomolar range. Therefore, the GA enzymatic detection method was combined with the ECL method for a highly sensitive detection of GA in human serum albumin and in the saliva sample. Here, the standard curve was constructed using model substrate, FZK, between 0.1 and 2 μM, and GA in human serum albumin was measured in this range. Also, we successfully demonstrated the detection limit of 0.1 μM GA in human serum albumin sample using ECL, which has seen improvement of about 70 times more than the colorimetric methods. The detection of GA in real saliva sample suggested that sample dilution of 5 times may be necessary to suppress the ECL quenching effect by impurities.