BACKGROUND: Organic chemicals have been known to cause allergic diseases such as bronchial asthma and hypersensitivity pneumonitis; however, the possibility that they do not cause irreversible pulmonary fibrosis has not been considered. Polyacrylic acid (PAA), an organic chemical, has caused irreversible progressive pulmonary fibrosis in exposed workers, indicating its potential to induce pulmonary inflammation and fibrosis. Although intratracheal instillation studies are commonly used for evaluating lung pathology, traditional methods face challenges with chemical substances, particularly nanoparticles, which tend to aggregate in suspension and prevent uniform pulmonary distribution. Such aggregation alters the qualitative and quantitative responses to lung injury, limiting accurate assessment of lung pathology. To overcome this limitation, we developed a 'molecular dispersion method' that uses pH modification to negative charges to PAA particles, maintaining their dispersion. Using this method, we investigated the effects of PAA on pulmonary inflammation and fibrosis in a rat model. METHODS: F344 rats were intratracheally instilled with PAA using molecular dispersion (0.1 mg/rat, 1.0 mg/rat), PAA without molecular dispersion (1.0 mg/rat), and normal saline (control group). Rats were sacrificed at 3 days, 1 week, 1 month, 3 months, and 6 months after exposure to examine inflammatory and fibrotic responses. RESULTS: PAA caused persistent increases in neutrophil influx in the bronchoalveolar lavage fluid (BALF) from 3 days to 1 month following instillation. In histopathological findings, the group with molecular dispersion had almost no inflammatory masses in the lung tissue compared to the group without molecular dispersion, and exhibited relatively uniform dispersion. CONCLUSION Intratracheal instillation of dispersed PAA induced neutrophil inflammation and fibrosis in the rat lung, suggesting that PAA might have pulmonary inflammogenicity and fibrogenicity. Intrapulmonary dispersion of PAA particles following intratracheal instillation studies using the molecular dispersion method was similar to that following inhalation studies.
Animals ; Rats, Inbred F344 ; Acrylic Resins/adverse effects* ; Rats ; Inhalation Exposure/adverse effects* ; Male ; Pulmonary Fibrosis/pathology* ; Pneumonia/pathology* ; Lung/pathology* ; Bronchoalveolar Lavage Fluid/cytology*

It has been suggested that inspiratory muscles fatigue impairing blood flow to the active limb muscle via respiratory muscle metaboreflex. The purpose of this study was to investigate the effects of inspiratory muscle fatigue on exercise performance and muscle tissue oxygenation in high-intensity exercise takes about 3.5~5min. Eleven healthy males subjects performed two conditions of constant-load exercise to exhaustion (TTE) on a cycle ergometer at 100% of maximal oxygen uptake. The two conditions—inspiratory muscle fatiguing (IMF) and non-fatiguing (PLA) —which had different intensity inspiratory resistance breathing (IRB) were performed before exercise. Muscle tissue oxygenations were measured by deoxyhemogrobin (HHb), oxygen saturation index (StO2) from right vastus lateralis during TTE. All data were analyzed from nine subjects whose inspiratory muscle were fatigued by IRB in IMF. Results: TTE was significantly shorter in IMF compare to PLA (244±31s vs. 268±38s, p<0.05). HHb was significantly higher and StO2 was significantly lower in IMF than in PLA (p<0.05). Conclusion: High-intensity exercise completed in 3.5~5 minutes, it was suggested that inspiratory muscle fatigue reduced the oxygen deriver to active limb muscle, resulting in decrease exercise performance. Improving function of inspiratory muscles, such as in inspiratory muscle training, may improve oxygenation of the active limb muscle and enhance exercise performance.

OBJECTIVE: The provisional diagnosis of progressive supranuclear palsy (PSP) depends on a combination of typical clinical features and specific MRI findings, such as atrophy of the tegmentum in the midbrain. Atrophy of the superior cerebellar peduncle (SCP) distinguishes PSP from other types of parkinsonism. Histological factors affect the conventional fluid-attenuated inversion recovery (FLAIR) signals, such as the extent of neuronal loss and gliosis. METHODS: We investigated patients with PSP to verify the percentage of patients with various PSP phenotypes presenting a high signal intensity in the SCP. Three interviewers, who were not informed about the clinical data, visually inspected the presence or absence of a high signal intensity in the SCP on the FLAIR images. We measured the pixel value in the SCP of each patient. Clinical characteristics were evaluated using the Mann-Whitney test, followed by the χ² test. RESULTS: Ten of the 51 patients with PSP showed a high signal intensity in the SCP on FLAIR MRI. Higher pixel values were observed within the SCP of patients with a high signal intensity in the SCP than in patients without a high signal intensity (p < 0.001). The sensitivity and specificity of the high signal intensity in the SCP of patients with PSP was 19.6% and 100%, respectively. This finding was more frequently observed in patients with PSP with Richardson's syndrome (PSP-RS) (25.7%) than other phenotypes (6.2%). CONCLUSION: The high signal intensity in the SCP on FLAIR MRI might be an effective diagnostic tool for PSP-RS.
Atrophy ; Diagnosis ; Gliosis ; Humans ; Magnetic Resonance Imaging ; Mesencephalon ; Neurodegenerative Diseases ; Neurons ; Parkinsonian Disorders ; Phenotype ; Sensitivity and Specificity ; Supranuclear Palsy, Progressive