Reducing exposure levels of immersion washing workers to ortho-phthalaldehyde by improving exhaust systems.

OBJECTIVES: The American Conference of Governmental Industrial Hygienists recommends a threshold limit value-ceiling (TLV-C) of 0.1 ppb for occupational exposure to ortho-phthalaldehyde (OPA) used in washing endoscope probes. To adhere to this extremely low exposure limit, this case study aimed to reduce OPA exposure concentrations of workers during immersion washing of an endoscope probe body. This was achieved by attaching a new duct and hood to the existing ceiling exhaust system. METHODS: The type of hood was determined by calculating and comparing the capture velocity obtained by assuming either an exterior or an enclosing hood. Additionally, the effect on improving the working environment was tested before and after the installation of the hood by measuring the OPA vapor concentration. RESULTS: The calculated capture velocities of the exterior and enclosing hoods were 0.05 m/s and 0.19 m/s, respectively. Considering the operability, the exterior hood was more appropriate; however, the calculated capture velocity indicated potential inadequacy in meeting the TLV-C requirement, leading to the adoption of the enclosing hood. The OPA vapor concentration in ceiling value measurements taken after the enclosing hood was fitted was reduced to 0.2 ppb, that is, 1/10 of the original concentration. CONCLUSIONS: Although the environmental concentration after the improvement still exceeded the TLV-C of 0.1 ppb, this study's findings indicate that even substances with extremely low occupational exposure limits can be managed with appropriate local exhaust ventilation.

Estimating core body temperature using electrocardiogram signals.

Suppressing the elevation in core body temperature is an important factor in preventing heatstroke. However, there is still no non-invasive method to sense core body temperature. This study proposed an algorithm that estimates core body temperature based on electrocardiogram signals. A total of 12 healthy men (mean age ± SD = 39.6 ± 13.4) performed an ergometric exercise load test under two conditions of exercise load in an environmental chamber adjusted to a temperature of 35°C and humidity of 50%. Vital sensing data such as electrocardiograms, core body temperatures, and body surface temperatures were continuously measured, and physical data such as body weight were obtained from participants pre- and post-experiment. According to basic physiological knowledge, heart rate and body temperature are closely related. We analyzed the relationship between core body temperature and several indexes obtained from electrocardiograms and found that the amount of change in core body temperature had a strong relationship with analyzed data from electrocardiograms. Based on these findings, we developed the amount of change in core body temperature estimation model using multiple regression analysis including the Poincaré plot index of the ECG R-R interval. The estimation model showed an average estimation error of -0.007°C (average error rate = -0.02%) and an error range of 0.457-0.445°C. It is suggested that continuous core body temperature change can be estimated using electrocardiogram signals regardless of individual characteristics such as age and physique. Based on this applicable estimation model, we plan to enhance estimation accuracy and further verify efficacy by considering clothing and environmental conditions.

Privacy-Preserved Fall Detection Method with Three-Dimensional Convolutional Neural Network Using Low-Resolution Infrared Array Sensor.

Due to the rapid aging of the population in recent years, the number of elderly people in hospitals and nursing homes is increasing, which results in a shortage of staff. Therefore, the situation of elderly citizens requires real-time attention, especially when dangerous situations such as falls occur. If staff cannot find and deal with them promptly, it might become a serious problem. For such a situation, many kinds of human motion detection systems have been in development, many of which are based on portable devices attached to a user's body or external sensing devices such as cameras. However, portable devices can be inconvenient for users, while optical cameras are affected by lighting conditions and face privacy issues. In this study, a human motion detection system using a low-resolution infrared array sensor was developed to protect the safety and privacy of people who need to be cared for in hospitals and nursing homes. The proposed system can overcome the above limitations and have a wide range of application. The system can detect eight kinds of motions, of which falling is the most dangerous, by using a three-dimensional convolutional neural network. As a result of experiments of 16 participants and cross-validations of fall detection, the proposed method could achieve 98.8% and 94.9% of accuracy and F1-measure, respectively. They were 1% and 3.6% higher than those of a long short-term memory network, and show feasibility of real-time practical application.

Evaluation of the ceiling levels of ortho-phthalaldehyde exposure among health care workers engaged in endoscope disinfection: A new methodology using video-exposure monitoring.

OBJECTIVES: The present study aimed to develop a method for measuring the ceiling level of ortho-phthalaldehyde (OPA) exposure and evaluate the ceiling levels of OPA exposure among health care workers who handle disinfectant solutions containing OPA for the disinfection of endoscopes. METHODS: The study consisted of a preliminary survey and main survey. In the preliminary survey, processes involving high-concentration exposure to OPA were identified by video-exposure monitoring (VEM). In the main survey, the ceiling levels of OPA exposure for high-concentration exposure processes identified from the results of the preliminary survey were determined using a measuring method combining sampling using a 2,4-dinitrophenylhydrazine-silica cartridge and analysis by high-performance liquid chromatography tandem mass spectrometry. RESULTS: In the preliminary survey, seven processes involving high-concentration exposure to OPA were identified by VEM. The duration of each process was short, lasting from 20 seconds to a few minutes. In the main survey, the OPA concentrations for the identified high-concentration exposure processes ranged from 1.18 to 4.49 ppb, which markedly exceeded the threshold limit value ceiling (TLV-C) of 0.1 ppb recommended by the American Conference of Governmental Industrial Hygienists. CONCLUSIONS: The method for measuring the ceiling level of OPA exposure was established using VEM and the highly sensitive method of chemical analysis; and we successfully evaluated the ceiling levels of OPA exposure among health care workers engaged in endoscope disinfection. This approach can also be applied to other chemical substances with recommended TLV-Cs, and important information for reducing exposure can thus be obtained.

[A method to extract signals related to fatigue during visual display terminal (VDT) operation using independent component analysis].

With the recent, rapid developments of computers, adaptation between the human being and computer is being improved. On the other hand, mental fatigue is increased by continuous, long-time use. The problem of mental fatigue is now a new focus of research. This study proposes a method of evaluating mental fatigue. In this study, we used a method to extract signals related to fatigue using Independent Component Analysis (ICA). The subjects were 10 male students. After assuming a workload of simulated visual display terminal (VDT) operation for 30 min, the subjects sat in a relaxed position for 30 min. In this process, we measured work performance, subjective symptoms of feelings of fatigue and physiological measures. As a result, there was a high value of the correlation coefficient between these signals and the subjective symptoms of feeling of fatigue. We suggest that by using ICA we can determine the relationship between Independent Components and subjective feelings of fatigue for those under work stress, work strain and in a state of fatigue and stress. However, further experiments are needed to obtain conclusive findings of our research.

TNF receptor type I-dependent activation of innate responses to reduce intestinal damage-associated mortality.

BACKGROUND & AIMS: Ligation of tumor necrosis factor (TNF) receptors (TNFRs) with TNF plays a critical role in the pathogenesis of human inflammatory bowel disease (IBD). However, it remains unclear which cell types activated through TNFR-associated signaling cascades are involved in the pathogenesis of colitis. METHODS: Recombination activating gene-1 (RAG) knockout (KO) (no T or B cells)-based TNFR double and triple KO mice were generated. Bone marrow (BM) chimera mice in which BM-derived myeloid cells, but not colonic epithelial cells (CECs), express TNFRs were also generated. Colitis was induced by administration of dextran sodium sulfate (DSS) in distilled water. Murine lines and chimeras were assessed for disease severity, histopathology, apoptotic cell rate, epithelial proliferation, and bacterial invasion rate. RESULTS: Following DSS administration, mice lacking both RAG and TNFR1 exhibited a high mortality (>80%) rate with an impaired CEC regeneration compared with RAG KO and RAG x TNFR2 double KO (DKO) mice. Transplantation of RAG KO-derived BM cells restored CEC regeneration and rescued the majority of recipient RAG x TNFR1 DKO mice from DSS-induced mortality. After BM transplantation, RAG x TNFR1 DKO mice exhibited an increased rate of apoptosis in the colonic lamina propria macrophages in association with the activation of caspases. In addition, BM reconstitution directly or indirectly enhanced the proliferation of CECs by activating mitogen-activated protein kinase and phosphoinositide-3 kinase/Akt pathways. CONCLUSIONS: TNFR1-signaling cascade in colonic myeloid lineage cells contributes to the suppression of acute damage-associated mortality presumably by controlling CEC homeostasis.

Role of mammalian chitinases in inflammatory conditions.

It has been hypothesized that dysregulated host/microbial interactions play a pivotal role in the pathogenesis of inflammatory bowel disease. However, the exact mechanisms underlying the induction and perpetuation of the intestinal disorder are unclear. Recently, we unexpectedly discovered significantly upregulated gene expression of chitinase 3-like-1 in inflamed colon of the dextran sulfate sodium-induced colitis model by employing the DNA-microarray analysis. Chitinase 3-like-1 has a chitin binding ability, but lacks the enzymatic activity of lysing microbial cell wall. Chitinase 3-like-1 protein is mainly expressed in colonic epithelial cells and macrophages in the inflamed colon of dextran sulfate sodium-induced colitis. Chitinase 3-like-1, which can be upregulated after pro-inflammatory cytokine stimulation, possesses an ability to enhance the adhesion and internalization of intracellular bacteria into colonic epithelial cells. Most importantly, in vivo neutralization of chitinase 3-like-1 significantly suppressed the development of dextran sulfate sodium-induced colitis by dramatically decreasing the bacterial adhesion and invasion into colonic epithelial cells. Furthermore, anti-chitinase 3-like-1 antibody-treated mice exhibited a significantly lower load of Salmonella typhimurium in peripheral organs as compared to control rabbit IgG-treated mice. Recently, it has been reported that acidic mammalian chitinase is expressed in the setting of T helper-2-associated inflammation and subsequently induces airway hyperresponsiveness in allergic asthma patients. In addition, pan-chitinase inhibitor significantly ameliorates T helper-2-mediated inflammation and airway hypersensitivity. These studies provide to be a novel insight into the physiological role of mammalian chitinases in host/microbial interactions, and inhibition of chitinase activity would be considered a novel therapeutic strategy of allergic and inflammatory disorders.

[Fatigue estimation of visual display terminal (VDT) workers by physiological data--preliminary study of a new computer program for VDT work analysis].

The methods for assessing VDT workload based on individual capabilities are necessary to evaluate general fatigue by VDT work. We have developed a new computer program for assessing data entry performance of each individual. Four healthy male volunteers conducted a data entry task at their own pace using this program under a controlled environment. They performed the task for 30 minutes twice with 10 minutes rest between them. As a result, the average number of inputs was 133.2 characters/min in the first task and 129.1 characters/min after taking the rest. The error rate was 8.6% and 10.6% in each task. This program was useful to evaluate their data entry performance. We also reported our concern with a drop in nasal skin temperature that was observed during these VDT tasks.

Solid, cystic and vanishing tumors of the pancreas.

Two girls with pancreatic tumors are reported. They were presented with abdominal pain, no history of abdominal injury and no tumor marker abnormalities. Imaging studies demonstrated that the tumors in two patients had both solid and cystic components. The tumors gradually regressed and finally disappeared without any treatment. There has been no evidence of recurrence in 5- and 4-year observation periods, respectively. Pancreatic tumor with solid and cystic components may rarely be self-limited.