Nobumasa Aoki

Efficacy of colistin combination therapy in a mouse model of pneumonia caused by multidrug-resistant Pseudomonas aeruginosa

OBJECTIVES Multidrug-resistant Pseudomonas aeruginosa (MDRP) is becoming a serious problem in hospitals, especially in patients on ventilators. Recent data demonstrate that colistin may be effective for these patients, although limited in vitro and in vivo data are available. Our aim was to identify further characteristics of colistin for the therapy of pneumonia caused by MDRP. METHODS The effects of colistin on clinical strains of MDRP were examined by susceptibility test, time-kill assay, lipopolysaccharide (LPS)-blocking assay and a mouse pneumonia model, alone or in combination with other antibiotics. For the pneumonia model, mice were intranasally infected with bacteria and kept in hyperoxic conditions to mimic ventilator-associated pneumonia. RESULTS As a single agent, colistin exhibited the strongest activity of the antimicrobial agents tested. In combination, maximum synergy was observed with colistin plus rifampicin. As expected, co-incubation of bacterial culture supernatants with colistin significantly reduced LPS activities with an associated decrease in cellular cytotoxicity. In the pneumonia model, intranasal, but not intravenous, colistin combined with rifampicin produced maximum survival protection. Pharmacokinetic analysis of colistin demonstrated the superiority of intranasal administration, judging from the compartmentalized high concentration and the long half-life in the lungs. Moreover, colistin therapy significantly decreased both production of inflammatory cytokines and LPS activity, even at a dose effecting no change in the bacterial burden in the lung. CONCLUSIONS These data strongly suggest that colistin may be an important option for combination therapy against critical MDRP infections. For pneumonia especially, intranasal colistin with rifampicin may be beneficial not only for synergistic antibacterial activity, but also for blocking LPS.

Design methodology for a 1.0 GHz microprocessor

This paper describes the design methodology used to build an experimental 1.0 GigaHertz PowerPC integer microprocessor at IBMs Austin Research Laboratory. The high frequency requirements dictated the chip composition to be almost entirely custom macros using dynamic circuit techniques. The methodology presented will cover design and verification tools as well as circuit constraints and microarchitecture philosophy. The microarchitecture, circuits and tools were defined by the high frequency requirements of the processor as well as the aggressive design schedule and size of the design team.

Efficacy of Calcium-EDTA as an Inhibitor for Metallo-β-Lactamase in a Mouse Model of Pseudomonas aeruginosa Pneumonia

ABSTRACT In this study, we have evaluated the efficacy of calcium-EDTA (Ca-EDTA) as an inhibitor of bacterial metalloenzymes, such as metallo-β-lactamase (MBL) and other proteases, in a mouse model of Pseudomonas aeruginosa pneumonia. The simultaneous presence of Ca-EDTA (32 μg/ml) reduced the MICs of imipenem (IPM) in all MBL-producing P. aeruginosa isolates (IMP-1, -2, -7, and -10 and VIM-2) but not non-MBL-producing strains. In the pneumonia model, mice were intranasally infected with MBL-producing P. aeruginosa and then kept under conditions of hyperoxia to mimic ventilator-associated pneumonia. With both intranasal and subcutaneous administrations, Ca-EDTA significantly potentiated survival benefits of IPM compared to those of IPM alone. Ca-EDTA combination therapy induced a significant reduction of the bacterial burden in the lungs (P < 0.05). Furthermore, the inhibition activity of Ca-EDTA against MBL activity was confirmed by using the purified IMP-1 enzyme, which was characterized by a 50% inhibitory concentration (IC50) of 55 ± 8.2 μM. Finally, the protective effects of Ca-EDTA were demonstrated by culture supernatant-induced epithelial cell damage and acute lung injury in mice. These data suggest the therapeutic potential of Ca-EDTA not only by the blocking of MBLs but also by neutralizing tissue-damaging metalloproteases in P. aeruginosa infections.

Megalin Blockade with Cilastatin Suppresses Drug-Induced Nephrotoxicity

Nephrotoxicity induced by antimicrobial or anticancer drugs is a serious clinical problem. Megalin, an endocytic receptor expressed at the apical membranes of proximal tubules, mediates the nephrotoxicity of aminoglycosides and colistin, key antimicrobials for multidrug-resistant organisms. The mechanisms underlying the nephrotoxicity induced by vancomycin, an antimicrobial for methicillin-resistant Staphylococcus aureus, and cisplatin, an important anticancer drug, are unknown, although the nephrotoxicity of these drugs and gentamicin, an aminoglycoside, is suppressed experimentally with cilastatin. In the clinical setting, cilastatin has been used safely to suppress dehydropeptidase-I-mediated renal metabolism of imipenem, a carbapenem antimicrobial, and thereby limit tubular injury. Here, we tested the hypothesis that cilastatin also blocks megalin-mediated uptake of vancomycin, cisplatin, colistin, and aminoglycosides, thereby limiting the nephrotoxicity of these drugs. Quartz crystal microbalance analysis showed that megalin also binds vancomycin and cisplatin and that cilastatin competes with megalin for binding to gentamicin, colistin, vancomycin, and cisplatin. In kidney-specific mosaic megalin knockout mice treated with colistin, vancomycin, or cisplatin, the megalin-replete proximal tubule epithelial cells exhibited signs of injury, whereas the megalin-deficient cells did not. Furthermore, concomitant cilastatin administration suppressed colistin-induced nephrotoxicity in C57BL/6J mice. Notably, cilastatin did not inhibit the antibacterial activity of gentamicin, colistin, or vancomycin in vitro, just as cilastatin did not affect the anticancer activity of cisplatin in previous studies. In conclusion, megalin blockade with cilastatin efficiently suppresses the nephrotoxicity induced by gentamicin, colistin, vancomycin, or cisplatin. Cilastatin may be a promising agent for inhibiting various forms of drug-induced nephrotoxicity mediated via megalin in the clinical setting.

1-GHz fully pipelined 3.7-ns address access time 8 k/spl times/1024 embedded synchronous DRAM macro

This embedded-DRAM macro is designed as a DRAM cache for a future gigahertz microprocessor system based on a logic-based DRAM technology. The most notable feature of this macro is its ability to run synchronously with a gigahertz CPU clock in a fully pipelined fashion. It is designed to operate with a 1-GHz clock signal at 85/spl deg/C, nominal process parameters, and a 10% degraded V/sub DD/. The design is fully pipelined and synchronous with 16 independent subarrays. With 1-kb wide I/0 and a 1-GHz clock, the maximum data rate becomes 1 Tb per second. The address access time is 3.7 ns, four cycles with a 1-GHz clock. The subarray cycle time is 12 ns.

A 690 ps read-access latency register file for a GHz integer microprocessor

This paper describes a 690 ps read-access latency, 32 entry by 64 bit, 3 read-port, 2 write-port, register file with internal bypass. The register file has been fabricated as a pan of 1.0 GHz single-issue 64-bit PowerPC integer processor. Fabrication technology was IBM CMOS6X: 0.25-/spl mu/m drawn channel length, six-metal-layer (Al), 1.8 V nom. V/sub DD/. Self-resetting custom dynamic circuits are used exclusively. Read operation is accomplished by sensing the differential voltage of dual rail bit-lines. Read operation is followed by write operation in the same cycle. Whenever a read address is identical to a write address, the write data is forwarded by an output multiplexer. The register file has been tested and cycle by cycle operation in the processor environment verified at frequencies up to 1.0 GHz (1.8 V, 25/spl deg/C).

Prognostic implications of aspiration pneumonia in patients with community acquired pneumonia: A systematic review with meta-analysis

Aspiration pneumonia is thought to be associated with a poor outcome in patients with community acquired pneumonia (CAP). However, there has been no systematic review regarding the impact of aspiration pneumonia on the outcomes in patients with CAP. This review was conducted using the MOOSE guidelines: Patients: patients defined CAP. Exposure: aspiration pneumonia defined as pneumonia in patients who have aspiration risk. Comparison: confirmed pneumonia in patients who were not considered to be at high risk for oral aspiration. Outcomes: mortality, hospital readmission or recurrent pneumonia. Three investigators independently identified published cohort studies from PubMed, CENTRAL database, and EMBASE. Nineteen studies were included for this systematic review. Aspiration pneumonia increased in-hospital mortality (relative risk, 3.62; 95% CI, 2.65–4.96; P < 0.001, seven studies) and 30-day mortality (3.57; 2.18–5.86; P < 0.001, five studies). In contrast, aspiration pneumonia was associated with decreased ICU mortality (relative risk, 0.40; 95% CI, 0.26–0.60; P < 0.00001, four studies). Although there are insufficient data to perform a meta-analysis on long-term mortality, recurrent pneumonia, and hospital readmission, the few reported studies suggest that aspiration pneumonia is also associated with these poor outcomes. In conclusion, aspiration pneumonia was associated with both higher in-hospital and 30-day mortality in patients with CAP outside ICU settings.

Pneumonia Severity Assessment Tools for Predicting Mortality in Patients with Healthcare-Associated Pneumonia: A Systematic Review and Meta-Analysis

Background: In contrast to community-acquired pneumonia (CAP), no specific severity assessment tools have been developed for healthcare-associated pneumonia (HCAP) in clinical practice. Objectives: In this review, we assessed the clinical significance of severity assessment tools for HCAP. Methods: We identified related articles from the PubMed database. The eligibility criteria were original research articles evaluating severity scoring tools and reporting the outcomes of mortality in patients with HCAP. Results: Eight articles were included in the meta-analysis. The PORT score and CURB-65 were evaluated in 7 and 8 studies, respectively. Using cutoff values of ≥IV and V for the PORT score, the diagnostic odds ratios (DORs) were 5.28 (2.49-11.17) and 3.76 (2.88-4.92), respectively, and the areas under the curve (AUCs) were 0.68 (0.64-0.72) and 0.71 (0.67-0.75), respectively. Conversely, the AUCs for ≥IV and V were 0.71 (0.67-0.76) and 0.74 (0.70-0.78), respectively, when applied only to nonimmunocompromised patients. In contrast, when using cutoff values of ≥2 and ≥3 for CURB-65, the DORs were 3.35 (2.26-4.97) and 2.65 (2.05-3.43), respectively, and the AUCs were 0.65 (0.61-0.69) and 0.66 (0.62-0.70), respectively. Conversely, the AUCs for ≥2 and ≥3 were 0.65 (0.61-0.69) and 0.68 (0.64-0.72), respectively, when applied only to nonimmunocompromised patients. Conclusions: The PORT score and CURB-65 do not have substantial power compared with the tools for CAP patients, although the PORT score is more useful than CURB-65 for predicting mortality in HCAP patients. According to our results, however, these tools, especially the PORT score, can be more useful when limited to nonimmunocompromised patients.