Biomedical subjects
Shigefumi Maesaki
Publications and source records attributed to Shigefumi Maesaki.
Drug delivery system of anti-fungal and parasitic agents.
The antifungal agents for systemic mycoses are only a few in number. Among them amphotericin-B is still the most widely used drug, but substantial side effects including nephrotoxicity limits its clinical usefulness. Efforts to lower the toxicity are synthesis of AMPH-B analogues such as AMPH-B esters and encapsulation in lipid vesicles in the forms of liposomal AMPH-B (AmBisome), amphotericin-B lipid complex (Abelcet), amphotericin-B colloidal dispersion (Amphocil) and intralipid AMPH-B. The newer formulations are effective against wide range of fungi, may be given in higher doses and nephrotoxicity is lowered. Although all of them showed comparable efficacies, a standard formulation is yet to be determined. In Japan, studies on efficacies of lipid nanosphere-encapsulated AMPH-B are in progress. Special drug career systems and dosage forms, such as nanoparticles and liposomes hold the promise of overcoming the pharmacokinetic limitations. Nanoparticles are stable, solid colloidal particles consisting of macromolecular material and vary in size. Nanoparticles represent an interesting carrier system for the specific enrichment in macrophage containing organs like liver and spleen. Injectable nanoparticle carriers have important potential applications as in site-specific drug delivery. Modifications of liposomes in order to avoid uptake by RES, thus increase targetability has been attempted. A novel targetable liposome 34A-PEG-L modified with polyethylene glycol conjugated with MoAb, 34A specific to murine pulmonary epithelia has been evaluated in murine pulmonary aspergillosis. 34A-PEG-L-AmB showed higher tissue concentration and comparable efficacy than other AMPH-B formulations.
[Serodiagnosis for deep-seated mycoses].
Early diagnosis and treatment for an immunocompromised patient with a deep-seated mycosis are very important for the prognosis of the patient. Several methods of serodiagnosis for deep-seated mycosis have been developed and are clinically available. Detection of (1,3)-beta-D-glucan from serum samples of a patient can be evaluated with high sensitivity and specificity. Antigens detection test for fungi is another useful method for this serodiagnosis. A novel sandwich ELISA to detect galactomannan has higher sensitivity than the latex agglutination test. The cryptococcus capsular antigen detection technique is also very useful for patients with cryptococcosis. Thus, serodiagnosis for deep-seated mycosis appears to be a useful tool for treatment of immunocompromised patients.
Prolonged survival of mice with Pseudomonas aeruginosa-induced sepsis by rIL-12 modulation of IL-10 and interferon-gamma.
Interleukin-12 (IL-12) is thought to play an important role as a modulator of levels of IL-10 and interferon-gamma (IFN-gamma). To address the therapeutic effects of rIL-12 in an endogenous sepsis model in mice, which closely mimics the pathophysiology of septicaemia in man, the effects of rIL-12 on the levels of cytokines such as IL-10 and IFN-gamma, and on the survival of septic mice infected with Pseudomonas aeruginosa PAO1 were examined. First, in the endogenous sepsis model, the serum levels of IFN-gamma and IL-10 remained normal until days 8 and 10, respectively, when significant rises were seen. On day 11, levels of IFN-gamma returned to normal, but levels of IL-10 remained high. Interestingly, the IL-10 serum level reached a maximum 2 days later than the IFN-gamma serum level. In the light of these results, septic mice were given 0.01 microg of rIL-12 by intraperitoneal injection and the serum levels of endogenous cytokines and the survival times were examined. Mice treated with rIL-12 on days 5, 6 and 7 after infection survived significantly longer than control septic mice treated with saline only. Treatment with rIL-12 also led to a significant increase of the serum IFN-gamma level and a decrease of the serum IL-10 level on day 11. These results suggest that rIL-12 exerts therapeutic activity against endogenous sepsis caused by P. aeruginosa by stimulating proinflammatory responses and attenuating anti-inflammatory responses.
Two sporadic cases of infections due to Klebsiella pneumoniae resistant to expanded-spectrum cephalosporins in Japan.
TEM- or SHV-type extended-spectrum beta-lactamases (ESBLs) are of clinical concern in Europe and the United States, whereas bacterial strains producing such types of ESBLs have not been reported in Japan. We report here two cases of infection due to Klebsiella pneumoniae resistant to extended-spectrum cephalosporins in Japan. A ceftadizime-resistant K. pneumoniae strain (minimum inhibitory concentration; 32 &mgr;g/ml) was isolated transiently from the sputum of an 87-year-old woman with acute myocardial infarction and pneumonia (patient 1). Ceftadizime-susceptible and -resistant (minimum inhibitory concentration; >/=8 &mgr;g/ml) K. pneumoniae strains were isolated over a month from the blood, ascites, and feces of a 44-year-old man after bone marrow transplantation for acute lymphoblastic leukemia (patient 2); this patient died of K. pneumoniae sepsis and peritonitis followed by multiple organ failure. These isolates produced penicillinase, which was inhibited by clavulanic acid. A polymerase chain reaction (PCR) study showed that both isolates carried the SHV or LEN genes, but not the TEM, Toho-1, and IMP-1 genes. The pulsed-field gel electrophoresis profile of the strain isolated from patient 1 was genetically distinguishable from the profiles of the strains isolated from patient 2. It appeared that mutation of the beta-lactamase gene may have occurred in the body of patient 2, since the genotypes of the ceftadizime-susceptible and -resistant isolates from this patient were identical. Another 12 strains of K. pneumoniae, isolated from other patients in the same wards during the period in which the K. pneumoniae strains were isolated from patients 1 and 2, did not produce ESBLs and showed different genotypes. The results suggest that these isolates of resistant K. pneumoniae did not spread by cross transmission in the hospital and that the two cases were sporadic. Surveillance of these types of resistant bacteria is necessary, since they may well be present in other hospitals in Japan. Although the organisms are suspected to produce SHV-type ESBLs or LEN-1 variant beta-lactamases, further studies are necessary to specify the resistance genes.
Effect of Pseudomonas aeruginosa exotoxin A on endotoxin-induced tumour necrosis factor production in murine lung.
The ability of several Pseudomonas aeruginosa exo-enzymes, including exotoxin A (ETA), to induce inflammation and their influence on endotoxin-induced tumour necrosis factor (TNF) production in murine lung were evaluated. Intratracheal administration of lipopolysaccharide (LPS; 0.1-10 microg/mouse), 2(-1) LD50 of P. aeruginosa alkaline protease (7.5 microg/mouse) and elastase (1.2 microg/mouse) elevated total cell number and the percentage of neutrophils in broncho-alveolar lavage fluid (BALF), whereas ETA (0.1 microg/mouse) did not. LPS induced TNF production in BALF in a dose-dependent manner, whereas the P. aeruginosa exo-enzymes did not. When ETA was inoculated into the respiratory tract before LPS, production of TNF in BALF was significantly suppressed in a dose-dependent manner. ETA also suppressed TNF production by alveolar macrophages (AMs) stimulated with LPS in vitro. Flow cytometric analysis showed that ETA markedly reduced the expression of CD14 and CD11c/CD18 on the surface of AMs. ETA also depressed partially the expression of TNF-alpha mRNA in AMs. These findings suggest that ETA regulates TNF production in murine lung by suppressing LPS receptor expression, mRNA expression and protein synthesis and/or secretion of TNF.