THz phase-contrast computed tomography based on Mach-Zehnder interferometer using continuous wave source: proof of the concept.

In this study, we propose a THz computed tomography (CT) method based on phase contrast, which retrieves the phase shift information at each data point through a phase modulation technique using a Mach-Zehnder interferometer with a continuous wave (CW) source. The THz CT is based on first-generation CT, which acquires a set of projections by translational and rotational scans using a thin beam. From the phase-shift projections, we reconstruct a spatial distribution of refractive indices in a cross section of interest. We constructed a preliminary system using a highly coherent CW THz source with a frequency of 0.54 THz to prove the concept and performed an imaging experiment using phantoms to investigate its imaging features such as artifact-immune imaging, quantitative measurement, and selective detection.

Use of copper alloy for preventing transmission of methicillin-resistant Staphylococcus aureus contamination in the dermatology ward.

Metallic copper has been shown significantly to reduce methicillin-resistant Staphylococcus aureus (MRSA) contamination of the ambient surroundings of the beds of MRSA-carrying patients in dermatology wards. The aim of this study was to determine whether a bed sheet made of copper-coated film will reduce the spread of MRSA contamination in the environment of a heavily-colonized patient. The bacterial count was highest on the bed sheet. MRSA cell counts on the surface of the non-film-coated control sheet were high (6,600-11,000 colony forming units (cfu)), but those on the copper film were considerably lower (20-130 cfu). Use of metallic copper on the bed sheets of patients who are likely to be a source of MRSA contamination may help to prevent the spread of MRSA contamination in hospital wards.

The suppressive effect of Mekabu fucoidan on an attachment of Cryptosporidium parvum oocysts to the intestinal epithelial cells in neonatal mice.

The present study was done to investigate the effects of fucoidan and de-sulfated fucoidan isolated from the sporophyll of Undaria pinnatifida on the C. parvum adhesion to the cultured human intestinal cells and on the C. parvum infection in neonatal mice. The C. parvum adhesion to human Intestinal 407 cells was significantly suppressed by a low dose (1 micro g/ml) of Mekabu fucoidan (1 micro g/ml) (approx. 20.5 oocysts, p<0.0001), but not by de-sulfated fucoidan (approx. 138.2 oocysts), as compared with that (approx. 121.0 oocysts) of phosphate-buffered saline (PBS). The in vivo experiments presented here revealed that C. parvum oocysts in the fucoidan-treated mice was reduced nearly one fifth (approx. 5.4x10(4) oocysts, p<0.02) of the total number of oocysts (approx. 3.0x10(5)) in mice treated with PBS, but no significant effect of de-sulfated fucoidan was observed. These results show that (i) fucoidan effectively inhibits the growth of C. parvum in mice; and (ii) the ester sulfate of fucoidan is an active site to prevent the adhesion of C. parvum to the intestinal epithelial cells. Finally, we concluded that fucoidan might inhibit cryptosporidiosis through the direct binding of fucoidan to the C. parvum-derived functional mediators in the intestinal epithelial cells in neonatal mice.

[Distribution of Clostridium tetani in topsoil from Sagamihara, central Japan].

Despite reports of Clostridium tetani being isolated from soil in Kanazawa, Okinawa, and Tokyo, Japan, little has been studied about C. tetani distribution in other regions. We studied C. tetani in topsoil samples collected from private gardens, public road shoulders, a university campus, mountains, and fields in Sagamihara. C. tetani occurred in 8 of 35 soil samples (22.9%) and tetanus toxin in 7 of the 8 C. tetani-positive samples (87.5%). Contamination was clearly higher in soils from mountains near Tsukui-gun (Kanagawa Prefecture), Minamitsuru-gun, and Uenohara and Koshu cities (Yamanashi Prefecture) than in other regions. These findings suggest that tetanus toxin-producing strains of C. tetani tend to inhabit the topsoil of western Sagaminaha region, as a geographical feature.

[Inactivation of Cryptosporidium parvum oocysts in copper tubing].

We studied whether the infectivity of Cryptosporidium parvum oocysts for suckling mice could be inactivated by copper tubing or by other types of tubing used to construct water distribution systems, including stainless steel, rigid polyvinyl chloride (PVC), PVC-lined steel, polyethylene (PE), cross-linked PE, and polybutene (PB), using glass tubing as the control. Oocysts were incubated in each tubings for 24 hours. The extent of inactivation of infectious oocysts by copper tubing was -1.303 log, which significantly inactivated of infectivity. In contrast, other types of tubing had no significant effect on some oocyst infectivity, although PB did show a maximum inactivation of -0.313 log. 25% of oocysts showed degeneration morphologically after passing through copper tubing, while 0.3% to 1.8% showed degeneration after passing through other tubing. Significant inactivation of infectious oocysts was not caused by water in which copper tubing had been let stand for 24 hours, although it had a cupric ion (Cu2+) concentration of 2.4 mg/L. The direct contact of oocysts with copper surface resulted in a decrease in the recovery percentage of oocysts and generation of hydrogen peroxide (0.5 mg/L) after 24 h of incubation. The percentage of degenerating oocysts was 29%. Such cryptosporidicidal effects of the copper surface on oocysts were completely inhibited by overlaying the surface with a Millipore filter before adding oocysts and incubating oocysts in the presence of catalase, an antioxidant enzyme. These findings suggest that copper tubing inactivates infectious C. parvum oocysts cytotoxically which may be due to oxygen radicals generated by the interaction between Cu2+ and hydrogen peroxide on the tubing surface.

Novel pathogenetic mechanism in a clinical isolate of Yersinia enterocolitica KU14.

Yersinia enterocolitica induces a broad range of gastrointestinal syndromes, including acute enteritis. We previously reported that the clinical isolate, Y. enterocolitica KU14, which lacks pYV, was still capable of causing clinical infection. The present study demonstrated that KU14 did not trigger the death of macrophages in vitro, unlike WA-314 (ATCC51871, which harbors the pYV virulence plasmid). However, the intracellular growth of KU14 in the macrophages was greater than that of WA-C (ATCC51872, a non-plasmid harboring the derivative pYV plasmid). Treatment with a cholesterol-binding drug (beta-cyclodextrin) that affected lipid rafts resulted in a dramatic reduction in the intracellular growth of KU14. These data clearly indicate that the enhanced intracellular growth of KU14 is related to lipid raft-mediated infection.

[Antimicrobial ceramic for killing Legionella pneumophila in hot spring waters].

Killing of Legionella pneumophila by an antimicrobial ceramic was evaluated during culture in nine kinds of hot spring water at 40 degrees C. After 24 hours, the efficacy against L. pneumophila varied, depended on water quality. The strongest antibacterial effect was seen in chloride hot spring water from Wakayama and in deionized water. In four hot spring water samples (sulfur and hydrogen carbonate springs from Fukushima, simple thermals from Mie, and radioactive spring from Tottori), the decrease was < -2 log cfu after 48 hours. These results suggest that the antimicrobial ceramic is able to eradicate Legionella from hot spring waters.

Establishment of rat model of acute staphylococcal osteomyelitis: relationship between inoculation dose and development of osteomyelitis.

INTRODUCTION: Many animal models of acute and chronic osteomyelitis have been developed. In these models, osteomyelitic lesions are induced using sclerosing agents and foreign bodies with bacterial strains. In the present rat model, these sclerosing agents were not used. We assessed the relationship between inoculation dose and histological, radiological, and microbiological changes in the acute phase (1 week after inoculation) using this rat osteomyelitis model. MATERIALS AND METHODS: An experimental rat model of acute osteomyelitis was developed by direct inoculation of the virulent strain BB of Staphylococcus aureus into tibial bone without sclerosants. To examine the relationship between the inoculation dose of the bacteria and the progression of the osteomyelitis, the inoculated lesions were assessed for changes in histological, radiological, and bacteriological parameters at 1 week after infection. Serial dilutions of the bacteria [6 x 10(1) to 6 x 10(5) colony-forming units (CFU)/5 microl] suspended in saline or saline alone were inoculated into the proximal metaphysis of the tibia. RESULTS: Development of significant histological and radiological signs of osteomyelitis required an inoculum of at least 6 x 10(3) CFU/5 microl. The number of viable bacteria at the lesion reached a maximum of 6 x 10(3) CFU/5 microl. CONCLUSION: These results suggest that strain BB induces the development of acute staphylococcal osteomyelitis with clear infective destruction in the tibia, and that our model may be applied to the identification of virulence factors in studies of posttraumatic osteomyelitis.

[Physicochemical factors influencing distribution of Legionella species in Japanese hot springs].

We examined the relationship between the distribution of Legionella bacteria and various physicochemical characteristics of hot springs in Japan. Legionella bacteria were isolated from 52 (49.5%) out of 105 water samples, particularly from outdoor hot springs (67.3%). The bacterial count in the water samples positive for Legionella (86.5%) ranged from 10(1) to < 10(3) cfu/100 mL. L. pneumophila serogroup (SG) 4 (27.8%) was predominant in the water samples, followed by SG 5 (12.2%). The pulsefield gel electrophoresis (PFGE) patterns of chromosomal DNA for L. pneumophila SG 4 isolated from different parts of a hot spring resort were identical. Isolation of Legionella species from hot spring waters did not occur at pH 1.8-3.3, SO4(2-): > 780 mg/L, and H2SiO3: > 146 mg/L. The hot water-recirculating systems were applied to 18 out of 20 (90%) hot spring facilities which were found positive for Legionella. These results indicate that Legionella species are widespread in hot springs throughout Japan, except for waters with a low pH and non-recirculating waters, and that a single strain of L. pneumophila SG 4 is predominant in a particular hot spring resort.

[Disinfection of water of remove Legionella species: evaluation of an antimicrobial ceramic].

To evaluate the efficacy of an antimicrobial ceramic for killing Legionella strains in vitro, bacteria were exposed to the ceramic soaked in PBS at 25 degrees C or 42 degrees C. The number of L. pneumophila began to decrease significantly after 4 h of exposure at 25 degrees C and reached < 10 log cfu/ml after 12 h. A similar significant decrease was also observed after exposure at 42 degrees C. Furthermore, it was found that the antimicrobial ceramic showed bactericidal activity against six strains of Legionella isolated from various water sources, including L. pneumophila (serotype 1-4), L. micdadei, and L. dumoffii, after 24 h of exposure. The antimicrobial activity against L. pneumophila of the supernatant obtained by soaking the ceramic in PBS for 24 h was also assessed. Bactericidal activity of this supernatant was also noted. Analysis of the supernatant by ICP-MS resulted in the detection of eight metals (Mg, Al, Ca, Mn, Zn, Sr, Ag, and Ba) at a maximum concentration of 2.5 mg/l. When reconstituted PBS was made with all eight metals at the same concentrations as in the supernatant, the reconstituted PBS containing Ag alone and all metals showed significantly bactericidal activity against L. pneumophila, but PBS with only one metal component except Ag or a combination of Ag with Zn and/or Ca did not. These findings suggest that the antimicrobial ceramic possesses strong bactericidal activity against Legionella species and that eight metals released from the ceramic have a synergistic bactericidal effect against Legionella. When the antimicrobial ceramic was placed in hot spring water or cooling tower water instead of PBS, the number of L. pneumophila in the water decreased to < 10 log cfu/ml after 24 h of exposure and the bactericidal activity persisted for 5 weeks. These results indicate that the antimicrobial ceramic can be used to eradicate Legionella species contaminating various water sources.

Pretreatment of Pseudomonas aeruginosa with a sub-MIC of imipenem enhances bactericidal activity of neutrophils.

The influence of the pretreatment of Pseudomonas aeruginosa strain O1 (PAO-1) with a sub-minimum inhibitory concentration (MIC) of imipenem on bactericidal activity, phagocytosis, the production of oxygen radical intermediates, and the induction of apoptosis in murine peritoneal neutrophils, as well as the catalase activity in the bacteria in comparison with that of ceftazidime-treated bacteria were studied. Bacteria treated with imipenem at (1/4) MIC were killed at significantly higher rates by neutrophils than ceftazidime-treated and nontreated bacteria. However, antibiotic-treated bacteria showed similar numbers of bacteria-phagocytized neutrophils to those in untreated bacteria. Imipenem pretreatment of bacteria led to an increase in the production of oxygen radical intermediates by neutrophils and the inhibition of neutrophilic apoptosis following incubation, whereas these features did not occur in neutrophils incubated with nontreated and ceftazidime-treated bacteria. The catalase activity of bacteria was not suppressed by pretreatment with either antibiotic at (1/4) MIC. These findings suggest that the exposure of P. aeruginosa to a sub-MIC of imipenem enhances the susceptibility of the bacteria to neutrophilic killing and effectively modifies the physiological activities of neutrophils, but does not decrease bacterial catalase activity. These actions may account for the postantibiotic leukocyte enhancement (PALE) effect of a sub-MIC of imipenem in the host.

Apoptosis of intestinal crypt epithelium after Cryptosporidium parvum infection.

Using a neonatal mouse model of Cryptosporidium parvum infection, we investigated whether apoptosis of epithelial cells was induced in the small intestine. At the time when the number of C. parvum oocysts in the ileum was maximal, columnar goblet cells and absorptive cells showed a decrease in the ileal epithelium that was accompanied by a significant reduction in the height of the villi. A few apoptotic epithelial cells were also observed in the vicinity of the basal crypts where C. parvum was proliferating. Morphological changes of the villous structure and apoptotic epithelial cells associated with proliferation of the parasite were scarcely detected in the duodenum, cecum, and colon of the infected mice. These findings suggest that the loss of absorptive cells and goblet cells, and the apoptosis of intestinal epithelial cells, are common events in the ileum after C. parvum infection, and that epithelial apoptosis may have a significant role in the pathogenesis of cryptosporidiosis.

[Effect of the mixed-oxidant solution on infectivity of Cryptosporidium parvum oocysts in a neonatal mouse model].

Cryptosporidium parvum oocysts were exposed to the mixed-oxidant solution, which was electrochemically generated by Miox Water Disinfection Unit, and sodium hypochlorite in phosphate buffered saline (PBS, pH 7.2) or biologically treated wastewater at 25 degrees by using concentrations of residual chlorine of up to 5 mg/l and contact times of up to 8 h. The effect of two disinfectants on infectivity of the oocysts in a neonatal murine model was comparatively evaluated by determining the total number of oocysts recovered from the intestine. Exposure to the mixed-oxidant solution at 2 and 5 mg/l (residual chlorine) yielded a significant inactivation of infectivity in the dose- and exposure time-dependent manner, while exposure to 5 mg/l (residual chlorine) of sodium hypochlorite for contact times of up to 4 h produced no measurable inactivation of infectivity. Morphological examination also revealed a picture of degenerating oocysts after exposure to 5 mg/l (residual chlorine) of the mixed-oxidant solution, but not with sodium hypochlorite. When the oocysts were exposed to either biologically treated wastewater--or PBS-diluted the mixed-oxidant solution at 5 mg/l (residual chlorine) for 4 h, the disinfectants produced a significant inactivation of infectious oocysts. The decrease number of the oocysts was 0.8 log 10 in the former and 2.1 log 10 in the latter. These results demonstrate that the mixed-oxidant solution may be a useful disinfectant against Cryptosporidium oocysts, but appropriate applications need to be validated.

Production of macrophage inflammatory protein 3alpha (MIP-3alpha) (CCL20) and MIP-3beta (CCL19) by human peripheral blood neutrophils in response to microbial pathogens.

Effects of bacterial pathogens on the production of macrophage inflammatory protein 3alpha (MIP-3alpha) and MIP-3beta from human peripheral blood neutrophils were investigated. Neutrophils produced both chemokines by coincubation with either gram-positive or gram-negative bacteria. Neutrophils may initiate antigen-specific immune responses through the release of these chemokines that are capable of promoting selective recruitment of dendritic cells and T-cell subsets.