Behavior of rock wool in lungs after exposure by nasal inhalation in rats

To evaluate the safety of rock wool (RW fibers), we examined the biopersistence of a RW sample in the lungs of rats, based on the changes of fiber number and fiber size in terms of length and width, by a nose-only inhalation exposure study. Twenty male Fischer 344 rats (6-10 weeks old) were exposed to RW fibers at a concentration of 70 (21) fiber/m(3) and 30 (6.6) mg/m(3), arithmetic mean (geometric standard deviation), continuously for 3 h daily for five consecutive days. Five rats each were sacrificed shortly and at 1, 2, and 4 weeks after exposure, and their lung tissues were ashed by a low-temperature plasma-asher. Then, the numbers and sizes of fibers in the ashed samples were determined using phase-contrast microscope and computed image analyzer. The fiber numbers in the lungs 4 weeks after exposure significantly decreased from the baseline value, i.e., shortly after exposure (P < 0.05). The half-lives of RW fibers calculated from the one-compartment model were 32 days for total fibers and 10 days for fibers longer than 20 mum. The decrease of fiber number was 53.6% by 4 weeks after exposure (baseline group = 100%). Likewise, fiber sizes significantly decreased by 4 weeks after exposure (P < 0.05), probably because fibers were dissolved in body fluid, ingested by alveolar macrophages or discharged to outside of the body by mucociliary movement. In future studies, it is necessary to examine the long-term persistence of RW fibers in the lungs.

Incidence of Medical Errors by Interns in Japan / 医学教育

Recently, patient safety has become a social concern in Japan. Even though cases of “incidents” and “accidents” by interns have been collected and analyzed in each hospital, few published reports have concerned teaching hospitals. The purpose of this study was to identify the incidence of “incidents” and “accidents” by first-year and second-year interns in Japan.<BR>1) In August 2005, a questionnaire was mailed to 231 interns at 14 teaching hospitals. A total of 192 interns participated in this study, with a response rate of 83.1%.<BR>2) The number of cases of “incidents” and “accidents” involving interns since the start of their training was collected.An “incident” was defined as an error that was prevented before occurrence, whereas an “accident” was defined as an unplanned, unexpected, and undesired event with adverse consequences.<BR>3) Among first-year interns, “incidents” occurred at a rate of 0.79 per resident-month (95% confidence interval [CI]: 0.30-1.28), while “accidents” were observed at a rate of 0.13 per resident-month (95% CI: 0.06-0.20).<BR>4) Among second-year interns, “incidents” occurred at a rate of 0.24 per resident-month (95% CI: 0.14-1.34), and “accidents” were observed at a rate of 0.06 per resident-month (95% CI: 0.01-0.11).<BR>5) There was no significant difference in the number of cases of “incidents” and “accidents” in regards to sex, age, or the number of beds of teaching hospitals.

Factors Associated with Turnover Intention among Nurses in Small and Medium-Sized Medical Institutions

Objectives: The objective of this study was to evaluate factors associated with turnover intention among nurses in small and medium-sized medical institutions. Methods: A self-administered questionnaire survey was performed in 293 registered nurses, licensed practical nurses, and assistant nurses working full-time in various medical institutions. Multiple linear regression analysis was conducted, with turnover intention as the dependent variable, and nurses’ basic attributes and job satisfaction as independent variables. Results: As for nurses’ basic attributes, turnover intention was significantly associated with registered nurses, younger nurses and those with low satisfaction with sleep. As for nurses’ job satisfaction, the number of nurses with turnover intention was significantly higher for those with low satisfaction with salary, low satisfaction with welfare, poor implementation of fair salary raise and poor cooperation among nurses. Conclusion: Turnover intention may be reduced by the enhancement of trust in the organization, giving appropriate advice to young nurses and registered nurses, and developing measures for addressing sleep disorders.

Factors associated with turnover interntion among nurses in small and medium-sized medical institutions

<p><b>OBJECTIVES</b>The objective of this study was to evaluate factors associated with turnover intention among nurses in small and medium-sized medical institutions.</p><p><b>METHODS</b>A self-administered questionaire survey was performed in 293 registered nurses, licensed practical nurses, and assistant nurses working full-time in various medical institutions. Multiple linear regression analysis was conducted, with turnover intention as the dependent variable, and nurses' basic attributes and job satisfaction as independent variables.</p><p><b>RESULTS</b>As for nurses' basic attributes, turnover intention was significantly associated with registered nurses, younger nurses and those with low satisfaction with sleep. As for nurses' job satisfaction, the number of nurses with turnover intention was significantly higher for those with low satisfaction with salary, low satisfaction with welfare, poor implementation of fair salary raise and poor cooperation among nurses.</p><p><b>CONCLUSION</b>Turnover intention may be reduced by the enhancement of trust in the organization, giving appropriate advice to young nurses and registered nurses, and developing measures for addressing sleep disorders.</p>

Behavior of New Type of Rock Wool (HT Wool) in Lungs after Exposure by Nasal Inhalation in Rats

Objectives: Previous types of rock wool has been recently replaced with high-temperature wool (HT wool). HT wool is characterized by a chemical composition with a higher concentration of Al2O3 and a lower concentration of SiO2, lower biopersistence, and a higher melting point than previous types of rock wool. To evaluate the safety of HT wool, an asbestos substitute, we examined the biopersistence of HT wool in the lungs, based on changes in fiber count according to the length and fiber size (length and width), by performing a nose-only inhalation exposure study in rats. Methods: Male Fischer 344 rats were exposed to fibers at the target exposure concentration of 30 mg/m3 continuously for 3 hours daily for 5 consecutive days. Rats were sacrificed shortly after exposure, and 1, 2, and 4 weeks after exposure, and their lung tissues were incinerated at a low temperature. Then, fiber counts and sizes in the lungs were analyzed using a phase contrast microscope. Results: The fiber count in the lungs 4 weeks after exposure significantly decreased from the baseline value (shortly after exposure). The half-life of fibers calculated from the approximation curve was 34 days for all fibers and 11 days for fibers longer than 20 μm. Conclusions: Both the length and width significantly decreased 4 weeks after exposure, probably because fibers were ingested by alveolar macrophages, discharged to outside of the body by mucociliary movement, or lysed by body fluid. In future studies, it is necessary to examine the long-term persistence of fibers in the lungs.

The Cytotoxicity of Microglass Fibers on Alveolar Macrophages of Fischer 344 Rats Evaluated by Cell Magnetometry, Cytochemisry and Morphology

Objectives: The toxicity of microglass fibers (MG), one of the man-made mineral fibers, has not been sufficiently evaluated. The aim of the current study was to evaluate the cytotoxicity of MG in vitro. Methods: Alveolar macrophages were obtained from the bronchoalveolar lavage of male F344/N rats. The macrophages were exposed to MG at concentrations of 0, 40, 80, 160 and 320 μg/ml. The effects of MG on the macrophages were examined by cell magnetometry, LDH assay and morphological observation. Results: In the cell magnetometry experiment, a significant delay of relaxation (the reduction of remanent magnetic field strength) was observed in the cells treated with 160 and 320 μg/ml of MG in a dose-dependent manner. A significant increase in LDH release was also observed in the cells with 160 and 320 μg/ml in a dose-dependent manner. Changes in the cytoskeleton were observed after exposure to MG, by immunofluorescent microscopy using an α-tubulin antibody. Conclusions: The cytotoxicity of MG on alveolar macrophages was demonstrated with cell magnetometry. The mechanism of the toxic effects of MG was related to cytoskeleton damage.

A Course of Preventive Medicine / 医学教育

1) A field of preventive medicine is extremely wide. We focus on the post-primary clinical training courses executed in the departments of preventive medicine in medical schools, health administration offices in community and ministry, and occupational health.<BR>2) A physician is recommended to choose the department of medical schools after inquiry of the major field such as community health, occupational health, epidemiology or toxicology, etc.<BR>3) The Ministry of Health, Labour and Welfare qualifies physician no later than 5 years after graduation from medical school for employment as a technical officer of specialist.<BR>4) For community health officers, comprehensive knowledge is required.<BR>5) While about 2, 000 physicians are employed as occupational health physicians, a new style of physicians makes contract with several enterprises and sets oneself up as occupational health consultants.

The cytotoxicity of microglass fibers on alveolar macrophages of fischer 344 rats evaluated by cell magnetometry, cytochemisry and morphology

<p><b>OBJECTIVES</b>The toxicity of microglass fibers (MG), one of the man-made mineral fibers, has not been sufficiently evaluated. The aim of the current study was to evaluate the cytotoxicity of MGin vitro.</p><p><b>METHODS</b>Alveolar macrophages were obtained from the bronchoalveolar lavage of male F344/N rats. The macrophages were exposed to MG at concentrations of 0, 40, 80, 160 and 320 μg/ml. The effects of MG on the macrophages were examined by cell magnetometry, LDH assay and morphological observation.</p><p><b>RESULTS</b>In the cell magnetometry experiment, a significant delay of relaxation (the reduction of remanent magnetic field strength) was observed in the cells treated with 160 and 320 μg/ml of MG in a dose-dependent manner. A significant increase in LDH release was also observed in the cells with 160 and 320 μg/ml in a dose-dependent manner. Changes in the cytoskeleton were observed after exposure to MG by immunofluorescent microscopy using an α-tubulin antibody.</p><p><b>CONCLUSIONS</b>The cytotoxicity of MG on alveolar macrophages was demonstrated with cell magnetometry. The mechanism of the toxic effects of MG was related to cytoskeleton damage.</p>

Behavior of new type of rock wool (HT wool) in lungs after exposure by nasal inhalation in rats

<p><b>OBJECTIVES</b>Previous types of rock wool has been recently replaced with high-temperature wool (HT wool). HT wool is characterized by a chemical composition with a higher concentration of Al(2)O(3) and a lower concentration of SiO(2), lower biopersistence, and a higher melting point than previous types of rock wool. To evaluate the safety of HT wool, an asbestos substitute, we examined the biopersistence of HT wool in the lungs, based on changes in fiber count according to the length and fiber size (length and width), by performing a nose-only inhalation exposure study in rats.</p><p><b>METHODS</b>Male Fischer 344 rats were exposed to fibers at the target exposure concentration of 30 mg/m(3) continuously for 3 hours daily for 5 consecutive days. Rats were sacrificed shortly after exposure, and 1, 2, and 4 weeks after exposure, and their lung tissues were incinerated at a low temperature. Then, fiber counts and sizes in the lungs were analyzed using a phase contrast microscope.</p><p><b>RESULTS</b>The fiber count in the lungs 4 weeks after exposure significantly decreased from the baseline value (shortly after exposure). The half-life of fibers calculated from the approximation curve was 34 days for all fibers and 11 days for fibers longer than 20 μm.</p><p><b>CONCLUSIONS</b>Both the length and width significantly decreased 4 weeks after exposure, probably because fibers were ingested by alveolar macrophages, discharged to outside of the body by mucociliary movement, or lysed by body fluid. In future studies, it is necessary to examine the long-term persistence of fibers in the lungs.</p>

Multiple chemical sensitivity and idiopathic environmental intolerance (part one)

Multiple chemical sensitivity/idiopathic environmental intolerance (MCS/IEI) is a commonly used diagnostic term for a group of symptoms. These symptoms have been described and commented on for more than 15 years in the USA. Recently, it has also been observed in Japan. The main features of this syndrome are multiple symptoms involving in multiple organ systems that are precipitated by a variety of chemical substances with relapses and exacerbation under certain conditions when exposed to very low levels which do not affect the population at large. There are no laboratory markers or specific investigative findings. Although traditional medical organizations have not agreed on a definition for this syndrome due to the lack of obvious evidence to demonstrate the existence of these symptoms, it is being increasingly recognized. It constitutes an increasing percentage of the caseload at occupational/environmental medical clinics.Part one of this review article discusses pathophysiological theories, substances which cause symptoms, prevalence in the general and specific populations, past history and family history, and clinical symptoms of MCS/IEI patients.

Multiple chemical sensitivity and idiopathic environmental intolerance (part two)

Multiple chemical sensitivity/idiopathic environmental intolerance (MCS/IEI) is a commonly used diagnostic term for a group of symptoms without apparent organic basis. The symptoms are characteristic of dysfunction in multiple organ systems. They wax and wane fluctuate according to exposure to low levels of chemical agents in the patient's environment, and sometimes begin after a distinct environmental change or injury such an industrial accident or chemical introduced after remodeling. Although traditional medical organizations have not agreed on a definition for this syndrome, it is being increasingly recognized and makes up an increasing percentage of the caseload at occupational/environmental medical clinics.Part two of this review article discusses diagnosis, clinical examination, long-term follow up of MCS/IEI, and the role of physicians, research on odor and treatment, diseases with similar symptoms, and further research regarding MCS/IEI patients.

Multiple Chemical Sensitivity and Idiopathic Environmental Intolerance (Part Two)

Multiple chemical sensitivity/idiopathic environmental intolerance (MCS/IEI) is a commonly used diagnostic term for a group of symptoms without apparent organic basis. The symptoms are characteristic of dysfunction in multiple organ systems. They wax and wane fluctuate according to exposure to low levels of chemical agents in the patient’s environment, and sometimes begin after a distinct environmental change or injury such an industrial accident or chemical introduced after remodeling. Although traditional medical organizations have not agreed on a definition for this syndrome, it is being increasingly recognized and makes up an increasing percentage of the caseload at occupational/environmental medical clinics. Part two of this review article discusses diagnosis, clinical examination, long-term follow up of MCS/IEI, and the role of physicians, research on odor and treatment, diseases with similar symptoms, and further research regarding MCS/IEI patients.

Multiple Chemical Sensitivity and Idiopathic Environmental Intolerance (Part One)

Multiple chemical sensitivity/idiopathic environmental intolerance (MCS/IEI) is a commonly used diagnostic term for a group of symptoms. These symptoms have been described and commented on for more than 15 years in the USA. Recently, it has also been observed in Japan. The main features of this syndrome are multiple symptoms involving in multiple organ systems that are precipitated by a variety of chemical substances with relapses and exacerbation under certain conditions when exposed to very low levels which do not affect the population at large. There are no laboratory markers or specific investigative findings. Although traditional medical organizations have not agreed on a definition for this syndrome due to the lack of obvious evidence to demonstrate the existence of these symptoms, it is being increasingly recognized. It constitutes an increasing percentage of the caseload at occupational/environmental medical clinics. Part one of this review article discusses pathophysiological theories, substances which cause symptoms, prevalence in the general and specific populations, past history and family history, and clinical symptoms of MCS/IEI patients.