Invasion of fish parasite Prosorhynchoides ozakii (Trematoda: Bucephalidae) into Lake Kasumigaura and surrounding rivers of eastern Japan.

In 2019 to 2021, the golden mussel Limnoperna fortunei and several freshwater fishes were sampled from 22 sites of the Tone River system including Lake Kasumigaura, Honshu, Japan, to examine the invasion of bucephalid trematodes. The parasite species identification was performed by morphological observation and DNA barcoding based on the sequences of nuclear 28S rDNA and mitochondrial cytochrome c oxidase subunit 1 (cox1). A total of 1719 mussels were collected from 10 sites, and trematode-infected mussels were detected from 8 sites with prevalences between 0.3 and 42.9%. The sporocysts and cercariae were identified as Prosorhynchoides ozakii, a newly introduced species in the river system. A total of 700 fish individuals belonging to 24 species were collected from 15 sites. Two species of catfishes (Silurus asotus and Ictalurus punctatus) harbored mature or immature adults of Pr. ozakii in the intestine with prevalences between 8.3 and 20% including both host species. The metacercariae of Pr. ozakii were found from the fins and epidermis of 13 fish species from 10 sites (prevalence 4.8-100%). Fishes were heavily infected with metacercariae in fins, which were surrounded by the infiltration of hemocytes and rodlet cells. A population genetic analysis of Pr. ozakii did not show an obvious bottleneck, suggesting the possibility that the parasite was intentionally and repeatedly introduced into the river system.

Effects of body position on snoring in apneic and nonapneic snorers.

STUDY OBJECTIVES: The positional dependency of obstructive sleep apnea (OSA) is well known, but objective evidence for the positional effect on snoring is lacking. The aim of this study is to elucidate the effect of body position on snoring, and that of sleep stage as well. DESIGN: Retrospective analysis of the effects of body position and sleep stage on snoring in nonapneic snorers (snorer group) and OSA patients (apneic group). SETTING: A sleep laboratory in a national hospital in Japan. PATIENTS: Seventy-two patients who complained of habitual snoring and underwent overnight polysomnography. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: In the lateral position, most subjects in the snorer group showed decreased snoring both in time (p = 0.0004) and intensity (p = 0.0003), but subjects in the apneic group showed variable changes. In the apneic group, the positional dependency of snoring (the ratio of lateral value to supine value) was correlated with supine apnea-hypopnea index (AHI), that is, OSA patients with higher supine AHI tended to show increased snoring in the lateral position. AS to the effect of sleep stage, snoring was increased in deeper non-rapid eye movement sleep and decreased in rapid eye movement sleep in a given position. CONCLUSIONS: This study demonstrated that the positional dependency is different between nonapneic snorers and OSA patients. Most of the nonapneic snorers snore less in the lateral position than in the supine position in contrast to OSA patients who often fail to decrease snoring even in the lateral position.

Validation of a new system of tracheal sound analysis for the diagnosis of sleep apnea-hypopnea syndrome.

STUDY OBJECTIVES: To evaluate the validity of a novel method of using tracheal sound analysis for the diagnosis of sleep apnea-hypopnea syndrome. DESIGN: Retrospective analysis in consecutive patients. SETTING: A sleep clinic in a general hospital. PATIENTS: A total of 383 patients who were referred for suspected sleep apnea-hypopnea syndrome and underwent diagnostic polysomnography with sufficient quality. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Ordinary polysomnography with simultaneous tracheal sound recording was performed. The apnea-hypopnea index (AHI) was calculated as the number of apnea and hypopnea events per hour of sleep. Tracheal sounds were digitized and recorded as power spectra. An automated computer program detected transient falls (TS-dip) in the time series of moving average of the logarithmic power of tracheal sound. We defined the tracheal sound-respiratory disturbance index (TS-RDI) as the number of TS-dips per hour of examination. We also calculated the oxygen desaturation index (the number of SaO2 dips of at least 4% per hour of examination). The TS-RDI highly correlated with AHI (r = 0.93). The mean (+/- SD) difference between the TS-RDI and AHI was -8.4 +/- 10.4. The diagnostic sensitivity and specificity of the TS-RDI when the same cutoff value was used as for AHI were 93% and 67% for the AHI cutoff value of 5 and 79% and 95% for the AHI cutoff value of 15. The agreement between the TS-RDI and AHI was better than that between the oxygen desaturation index and AHI. CONCLUSIONS: The fully automated tracheal sound analysis demonstrated a relatively high performance in the diagnosis of sleep apnea-hypopnea syndrome. We think that this method is useful for the portable monitoring of sleep apnea-hypopnea syndrome.

Effect of body mass index on overnight oximetry for the diagnosis of sleep apnea.

Overnight oximetry is widely used for screening for the sleep apnea hypopnea syndrome (SAHS). The degree of desaturation at an apnea event is known to be affected by the degree of obesity. We hypothesized that the diagnostic ability of oximetry for SAHS is affected by the degree of obesity. A total of 424 consecutive patients referred for possible SAHS were studied. The subjects were classified into three groups of normal-weight, overweight and obese based on the body mass index (BMI). The apnea-hypopnea index (> or = 15 h(-1)) by polysomnography was used as the diagnostic gold standard. Oximetry data were automatically analyzed to calculate the oxygen desaturation index (ODI2/3/4:at 2%/3%/4% threshold). The diagnostic abilities of the ODI were different in the three BMI-groups at a given cutoff value, e.g. the sensitivity/specificity of ODI4 (cutoff = 15) were 54%/100%, 83%/ 97%, and 98%/78% for the normal-weight, overweight and obese groups, respectively (P < 0.0001). The gender and the age had no significant effect on the ability. We demonstrated the diagnostic sensitivity and specificity of the ODI for SAHS depended on the BMI. Oximetry as a screening tool for SAHS may become more useful by selection of a cutoff value appropriate for the BMI of each subject.