Hiroaki Shishido

Dexamethasone decreases blood flow in normal nerves and dorsal root ganglia

Study Design. An experimental physiologic and histologic study of dexamethasone effects on peripheral nerves. Objective. To characterize the effect of topically applied 0.4% dexamethasone on acute changes in nerve blood flow and subsequent histologic changes in rat sciatic nerve fibers. Summary of Background Data. Dexamethasone is an anti-inflammatory glucocorticoid used clinically to reduce the neural consequences of inflammation. Several reports of accidental injury to nerves after steroid injections have raised questions about the mechanisms involved in dexamethasone-induced neurotoxic injury. Methods. Nerve blood flow studies using a laser Doppler flowmeter were conducted in animals with stable temperature and arterial pressure. Dexamethasone 0.4%, 0.1 mL was applied topically to rat sciatic nerve in the following protocol groups: 1) nerve blood flow recording every 5 minutes for 30 minutes, and 2) initial nerve blood flow recording and repeat recording at 4 hours. Three additional animals had 30-minute nerve blood flow recordings in which normal saline was substituted for dexamethasone; these animals were used for control and to assure that the experimental preparation was viable throughout the observational period. Additional groups of two animals each received dexamethasone but were used only for neuropathologic observation at 2, 4, and 6 days after treatment. Neuropathologic studies were conducted on glutaraldehyde-fixed, plastic-embedded tissue. Results. Application of saline to the exposed sciatic nerves did not significantly change nerve blood flow from baseline values. Nerve blood flow values remained constant throughout the observational period. Dexamethasone, however, significantly reduced nerve blood flow in both the 30-minute and 4-hour groups. Some animals showed an initial transient increase in blood flow before nerve blood flow began to steadily decline to the final values reported. Neuropathologic changes were minimal and consisted only of edema and occasional subperineurial activation of Schwann cells. No demyelination or degeneration was seen. Conclusion. Dexamethasone causes statistically significant reductions in normal nerve blood flow at 30 minutes and 4 hours after topical application; however, the reduction is on average below the threshold for causing ischemic changes in the structure of peripheral nerve fibers.

ULTRASONOGRAPHIC ASSESSMENT OF THE FLEXOR PRONATOR MUSCLES AS A DYNAMIC STABILIZER OF THE ELBOW AGAINST VALGUS FORCE

Flexor pronator muscles (FPMs) play a key role in stabilizing the elbow joint against valgus forces. However, no studies have investigated the in vivo kinematics of FPMs against these forces on the elbow. This study aimed to clarify the in vivo contribution of each FPM as a dynamic stabilizer in a clinical situation.Twelve healthy volunteers participated in this study. Verbal informed consent was obtained from all subjects. The elbow was flexed to 90 degrees, and the forearm was placed in the neutral position. Manual valgus stress was applied to the elbow joint until maximal shoulder external rotation was achieved. The width of the ulnohumeral joint space and the ulnar shift of the sublime tubercle were measured before and after isometric contraction of FPMs using ultrasonography.The horizontal distances were decreased 1.1±0.6 mm after forearm pronation, 0.6±0.5 mm after wrist palmar flexion, 0.1±0.4 mm after wrist ulnar flexion, and 0.2±0.5 mm after finger flexion. Significant changes were observed during forearm pronation, wrist palmar flexion, and finger flexion but not during wrist ulnar flexion (p<0.05). The sublime tubercle was significantly shifted 0.5±0.1 mm medially after forearm pronation, 0.2±0.1 mm medially after wrist palmar flexion, and 0.1±0.1 mm laterally after wrist ulnar flexion and finger flexion (p<0.05). The FPMs, especially the pronator teres and the flexor carpi radialis, function as dynamic stabilizers against elbow valgus stress. The results of this study may be useful in developing injury prevention and rehabilitation strategies for throwing injuries of the elbow.

Changes in Hepatobiliary Enzyme Abnormality After the Great East Japan Earthquake: The Fukushima Health Management Survey

Although the incidence of hepatobiliary enzyme abnormality increased immediately after the Great East Japan Earthquake and subsequent Fukushima Daiichi Nuclear Power Plant accident, longer-term trends remain unclear. The aims of this study were to determine longer-term trends in hepatobiliary enzyme abnormality and to elucidate lifestyle factors associated with such changes among residents of a nuclear-disaster-affected area. This longitudinal survey enrolled 20,395 adults living in the vicinity of Fukushima Daiichi Nuclear Power Plant. Data were obtained from the records of annual health checkups of adults aged ≥40 years between 2011 and 2012. Follow-up examinations were conducted from June 2013 to March 2014. Associations were assessed between changes in hepatobiliary enzyme abnormality immediately and 3–4 years after the disaster and lifestyle factors. The overall prevalence of hepatobiliary enzyme abnormality significantly decreased over the study period, from 29.9% to 27.1%. Multivariate logistic regression analysis revealed significant associations between improved hepatobiliary enzyme abnormality and improvements in daily physical activity and frequency of breakfast consumption. The results suggest that improvements in daily physical activity and frequency of breakfast consumption significantly reduced the incidence of hepatobiliary enzyme abnormality 3–4 years after the Great East Japan Earthquake and Fukushima Daiichi Nuclear Power Plant accident.

Persistent prevalence of polycythemia among evacuees 4 years after the Great East Japan Earthquake: A follow-up study

We previously reported that the lifestyle of evacuees significantly increased the prevalence of polycythemia compared with non-evacuees at an average of 1.6 years (2011–2012) from the previous annual health checkup before the Great East Japan Earthquake (GEJE). Here we analyzed how the prolonged evacuation affected the prevalence of polycythemia an average of 2.5 years (2013–2014) after the previous data. Subjects were individuals aged 40–90 years living in the vicinity of the Fukushima Daiichi Nuclear Power Plant in Fukushima Prefecture who had attended the annual health checkups since 2008. The prevalence of polycythemia and changes in its defining factors of red blood cell count (RBC), hemoglobin (Hb) level, hematocrit (Ht) level were compared between before and after the GEJE in 7713 individuals (3349 men and 4364 women) receiving follow-up examinations both 2011–2012 and 2013–2014. RBC, Hb levels and Ht levels in 2011–2012 were higher among evacuees than non-evacuees in both men and women. However, all levels in 2013–2014 were on the decline from those in 2011–2012. On the other hand, among evacuees, Hb and Ht levels continued to be higher than before the GEJE in both men and women evacuees. The prevalence of polycythemia, which was diagnosed if one of the defining factors was beyond the standard value, was significantly higher among evacuees than non-evacuees regardless of the presence or the absence of overweight/obesity, smoking, and hypertension. Therefore, prolonged evacuation is a cause of polycythemia even 3 to 4 years after the GEJE and regular health management of evacuees is important.

Evacuation is a risk factor for diabetes development among evacuees of the Great East Japan earthquake: A 4-year follow-up of the Fukushima Health Management Survey

Diabetes & Metabolism - In Press.Proof corrected by the author Available online since mardi 7 novembre 2017