Exploring the experiences and learning of young primary care physicians in disaster-affected areas: A qualitative study on the Great East Japan Earthquake.

Background: Primary care physicians (PCPs) play a critical role in disaster medicine. However, it is unclear how PCPs who provide chronic support to disaster-affected areas learn from their experiences. Methods: This qualitative study investigates the learnings of young PCPs who provided medical care during the chronic phase of the Great East Japan Earthquake disaster. Results: Thematic analysis of interviews with five physicians revealed the challenges faced by them and their learnings in providing medical support to disaster-affected areas. Conclusions: They not only learned medical skills but also humanistic aspects such as empathizing with the survivors' loss.

Accuracy of LAMP-TB Method for Diagnosing Tuberculosis in Haiti.

The procedure of ultra-rapid extraction (PURE) and loop-mediated isothermal amplification for tuberculosis (LAMP-TB) is a simple and rapid manual tuberculosis diagnostic with medium-throughput capability. Because of its simplicity, this method could be useful in resource-limited conditions such as microscopy centers in developing countries. This study was conducted to evaluate the clinical performance of this method in a point-of-care setting. The performance was compared to that of smear microscopy and liquid culture in a hospital laboratory in Haiti, which is considered a representative facility for the implementation of this method. The sensitivity, based on culture-positivity, was 86% (95% confidence interval: 81.3-90.3%) and that based on the smear-negative and culture-positive results was 51% (38.7-63.5%). The specificity based on sample negativity for both smear and culture was 98.4% (96.8-99.2). These results are nearly equivalent to those of a clinical study performed in Japan and are comparable with those of other nucleic acid amplification methods. Thus, approximately 18% more tuberculosis patients could be identified by adding the LAMP-TB method to routine smear microscopy in field settings in Haiti. In addition, it is suggested that local technicians could perform LAMP-TB after only short-term training.

RD1 region in mycobacterial genome is involved in the induction of necrosis in infected RAW264 cells via mitochondrial membrane damage and ATP depletion.

It was shown that virulent Mycobacterium tuberculosis H37Rv induces necrosis of infected RAW264 cells at 24 h post infection while avirulent H37Ra and an attenuated H37Rv mutant that is deficient for RD1 region (H37RvDeltaRD1) cause less necrosis of the infected cells. While H37Rv caused damage of the mitochondrial inner membrane and decreased the level of intracellular ATP, H37RvDeltaRD1 did not exhibit these harmful effects in infected cells. On the other hand, there was no difference in the level of intracellular reactive oxygen species after infection with H37Rv or H37RvDeltaRD1, and the intracellular bacterial numbers of H37RvDeltaRD1 and H37Ra were comparable to that of H37Rv. These results suggested that some virulence factors of H37Rv may contribute to the necrosis of infected cells through induction of mitochondrial dysfunction and depletion of intracellular ATP. RD1 appeared to encode some components possibly playing a central role in the induction of host cell necrosis after M. tuberculosis infection.

Involvement of caspase-9 in the inhibition of necrosis of RAW 264 cells infected with Mycobacterium tuberculosis.

In order to know how caspases contribute to the intracellular fate of Mycobacterium tuberculosis and host cell death in the infected macrophages, we examined the effect of benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethane (z-VAD-fmk), a broad-spectrum caspase inhibitor, on the growth of M. tuberculosis H37Rv in RAW 264 cells. In the cells treated with z-VAD-fmk, activation of caspase-8, caspase-3/7, and caspase-9 was clearly suppressed, and DNA fragmentation of the infected cells was also reduced. Under this experimental condition, it was found that the treatment markedly inhibited bacterial growth inside macrophages. The infected cells appeared to undergo cell death of the necrosis type in the presence of z-VAD-fmk. We further found that z-VAD-fmk treatment resulted in the generation of intracellular reactive oxygen species (ROS) in the infected cells. By addition of a scavenger of ROS, the host cell necrosis was inhibited and the intracellular growth of H37Rv was significantly restored. Among inhibitors specific for each caspase, only the caspase-9-specific inhibitor enhanced the generation of ROS and induced necrosis of the infected cells. Furthermore, we found that severe necrosis was induced by infection with H37Rv but not H37Ra in the presence of z-VAD-fmk. Caspase-9 activation was also detected in H37Rv-infected cells, but H37Ra never induced such caspase-9 activation. These results indicated that caspase-9, which was activated by infection with virulent M. tuberculosis, contributed to the inhibition of necrosis of the infected host cells, presumably through suppression of intracellular ROS generation.

Streptomycin-dependent exhibition of cytokine-inducing activity in streptomycin-dependent Mycobacterium tuberculosis strain 18b.

Peritoneal exudate cells of mice were stimulated with a streptomycin-dependent Mycobacterium tuberculosis strain, 18b. Gamma interferon production by natural killer cells depending on interleukin-12 and interleukin-18 was induced only in the presence of a high dose of streptomycin. This study suggested the requirement of active bacterial metabolism for this host response.

Differences in gamma interferon production induced by listeriolysin O and ivanolysin O result in different levels of protective immunity in mice infected with Listeria monocytogenes and Listeria ivanovii.

Two pathogenic species in the genus Listeria, Listeria monocytogenes and Listeria ivanovii, are characterized by the production of hemolysins belonging to cholesterol-dependent cytolysins, listeriolysin O (LLO) and ivanolysin O (ILO), respectively. LLO, produced by L. monocytogenes, is able to induce gamma interferon (IFN-gamma) production and contributes to the generation of Th1-dependent protective immunity. On the other hand, nothing is known about the role of ILO, produced by L. ivanovii, in this regard. In this study, we immunized mice with 0.1 50% lethal dose (LD(50)) of L. monocytogenes and L. ivanovii. Protective immunity against a challenge with 10 LD(50) was generated in mice infected with L. monocytogenes, whereas L. ivanovii infection did not induce protection. After immunization, the level of IFN-gamma in serum samples was increased in mice given L. monocytogenes but not in those given L. ivanovii. To determine the IFN-gamma-inducing activity of cytolysins, recombinant protein was constructed. Recombinant ILO exhibited significantly lower IFN-gamma-inducing activity than LLO. By comparing the IFN-gamma-inducing activity of a chimera incorporating LLO and ILO, it was found that domains 1 to 3 of LLO were critical for IFN-gamma-inducing activity while the counterpart in ILO was unable to induce cytokine production. These results suggested that the weak ability of ILO to induce IFN-gamma production is responsible for the failure of L. ivanovii to generate effective protective immunity.