Diaphragm Ultrasonography: Reference Values and Influencing Factors for Thickness, Thickening Fraction, and Excursion in the Seated Position.

INTRODUCTION: Measurements of diaphragm function by ultrasonography are affected by body position, but reference values in the seated position have not been established for an Asian population. This study aimed to determine reference values for diaphragm thickness, thickening fraction, and dome excursion by ultrasonography and to investigate the effects of sex, height, and body mass index. METHODS: Diaphragm ultrasonography was performed on 109 seated Japanese volunteers with normal respiratory function who were enrolled between March 2022 and January 2023. Thickness, thickening fraction, and excursion were measured. Reference values and the measurement success rate were calculated. Multivariate analysis adjusted for sex, height, and body mass index was performed. RESULTS: The measurement success rate was better for thickness than for excursion. The mean (lower limit of normal) values on the right/left sides were as follows. During quiet breathing, thickness at end expiration(mm) was 1.7 (0.9)/1.6 (0.80), thickening fraction(%) was 50 (0.0)/52 (0.0), and excursion(cm) was 1.7 (0.5)/1.9 (0.5). During deep breathing, the thickening fraction was 111 (24)/107 (22), and the excursion was 4.4 (1.7)/4.1 (2.0). In multivariate analysis, body mass index was positively associated with thickness but not with the thickening fraction. CONCLUSION: The reference values in this study were smaller than those in previous reports from Europe. Considering that thickness is influenced by body mass index, using Western reference values in Asia, where the average body mass index is lower, might not be appropriate. The thickening fraction in deep breathing is unaffected by other items and can be used more universally.

Relationship Between Diaphragm Thickness, Thickening Fraction, Dome Excursion, and Respiratory Pressures in Healthy Subjects: An Ultrasound Study.

PURPOSE: Diaphragm ultrasonography is used to identify causes of diaphragm dysfunction. However, its correlation with pulmonary function tests, including maximal inspiratory (MIP) and expiratory pressures (MEP), remains unclear. This study investigated this relationship by measuring diaphragm thickness, thickening fraction (TF), and excursion (DE) using ultrasonography, and their relationship to MIP and MEP. It also examined the influence of age, sex, height, and BMI on these measures. METHODS: We recruited healthy Japanese volunteers and conducted pulmonary function tests and diaphragm ultrasonography in a seated position. Diaphragm ultrasonography was performed during quiet breathing (QB) and deep breathing (DB) to measure the diaphragm thickness, TF, and DE. A multivariate analysis was conducted, adjusting for age, sex, height, and BMI. RESULTS: Between March 2022 and January 2023, 109 individuals (56 males) were included from three facilities. The mean (standard deviation) MIP and MEP [cmH2O] were 72.2 (24.6) and 96.9 (35.8), respectively. Thickness [mm] at the end of expiration was 1.7 (0.4), TF [%] was 50.0 (25.9) during QB and 110.7 (44.3) during DB, and DE [cm] was 1.7 (0.6) during QB and 4.4 (1.4) during DB. Multivariate analysis revealed that only DE (DB) had a statistically significant relationship with MIP and MEP (p = 0.021, p = 0.008). Sex, age, and BMI had a statistically significant influence on relationships between DE (DB) and MIP (p = 0.008, 0.048, and < 0.001, respectively). CONCLUSION: In healthy adults, DE (DB) has a relationship with MIP and MEP. Sex, age, and BMI, but not height, are influencing factors on this relationship.

Crowned dens syndrome: A case series of 72 patients at eight teaching hospitals in Japan.

Background: Crowned dens syndrome (CDS) is characterized by calcification around the odontoid process, accompanied by neck pain. Although CDS is supposedly rare, we regularly diagnose and manage this condition, indicating a perception gap between previous studies and our experience. The purpose of this study was to determine the annual incidence of CDS, time to diagnosis in CDS, as well as the features of CDS. Methods: The study design was a retrospective case series study conducted at eight teaching hospitals in Japan. We identified CDS cases from April 2013-March 2015. CDS was diagnosed when patients had acute onset of neck pain and CT showed calcification around the dens and when other diagnoses were unlikely. Results: Seventy-two CDS cases were identified. Mean annual incidence was 4.6 ± 2.3 cases at each hospital. Among those with available data, 57 of 64 had limited rotation (89.1%). The diagnosis of CDS was made in general internal medicine or the emergency medicine department in 61 cases (84.7%). A total of 62 cases (86.1%) were diagnosed within 1 day of presentation, and the median time from initial presentation at the hospital to diagnosis was 0.0 days (25th-75th percentiles, 0.0-1.0). For treatment, NSAIDs were used in 56cases (77.8%) and acetaminophen in 20 cases (27.8%). Conclusion: CDS might be more common than has been reported to date. Time to diagnosis of CDS was within 1 day of visiting a teaching hospital. Cervical motion restriction is common in CDS and may be useful in establishing the diagnosis.

Phospholipase Cbeta serves as a coincidence detector through its Ca2+ dependency for triggering retrograde endocannabinoid signal.

Endocannabinoids mediate retrograde signal and modulate transmission efficacy at various central synapses. Although endocannabinoid release is induced by either depolarization or activation of G(q/11)-coupled receptors, it is markedly enhanced by the coincidence of depolarization and receptor activation. Here we report that this coincidence is detected by phospholipase Cbeta1 (PLCbeta1) in hippocampal neurons. By measuring cannabinoid-sensitive synaptic currents, we found that the receptor-driven endocannabinoid release was dependent on physiological levels of intracellular Ca(2+) concentration ([Ca(2+)](i)), and markedly enhanced by depolarization-induced [Ca(2+)](i) elevation. Furthermore, we measured PLC activity in intact neurons by using exogenous TRPC6 channel as a biosensor for the PLC product diacylglycerol and found that the receptor-driven PLC activation exhibited similar [Ca(2+)](i) dependence to that of endocannabinoid release. Neither endocannabinoid release nor PLC activation was induced by receptor activation in PLCbeta1 knockout mice. We therefore conclude that PLCbeta1 serves as a coincidence detector through its Ca(2+) dependency for endocannabinoid release in hippocampal neurons.

Prevalence of fatigue among postgraduate trainees in the United States and Japan.

BACKGROUND: The difference in prevalence of fatigue among postgraduate trainees between the United States and Japan is unknown. METHODS: A cross-sectional survey using Iowa Fatigue Scale was administered on postgraduate trainees in two internal medicine residency programs in New York and five postgraduate residency programs in Japan. RESULTS: Of the 393 trainees, 135 (34%) completed the survey. Seventy-seven (57%) were US trainees. Both fatigue (42% vs 81%) and severe fatigue (4% vs 19%) were more prevalent in Japan (P < .01). US trainees felt more productive during work hours but less fatigued. CONCLUSIONS: Fatigue was more prevalent among postgraduate trainees in Japan.