Reference values for hand grip strength, muscle mass, walking time, and one-leg standing time as indices for locomotive syndrome and associated disability: the second survey of the ROAD study

BackgroundWe established reference values for hand grip strength, muscle mass, walking time, and one-leg standing time as indices reflecting components of locomotive syndrome and associated disability using a large-scale population-based sample from the second survey of the Research on Osteoarthritis/Osteoporosis Against Disability (ROAD) cohort.MethodsWe measured the above-mentioned indices in 2,468 individuals ≥40 years old (826 men, 1,642 women; mean age 71.8 years) during the second visit of the ROAD study. Disability was defined as certified disability according to the long-term care insurance system through public health centres of each municipality.ResultsMean values for hand grip strength (weaker side), muscle mass of the thighs, walking time for 6 m at the usual pace, and the fastest pace for men were 32.7 kg, 7.0 kg, 5.6 s, and 3.7 s, respectively, and those for women were 20.8 kg, 5.2 kg, 5.9 s, and 4.1 s, respectively. The median values for one-leg standing time (weaker side) were 14 s for men and 12 s for women. The prevalence of disability in men aged 65–69, 70–74, 75–79, and ≥80 was 0.0, 1.0, 6.3, and 8.8%, respectively, and in women was 3.4, 3.5, 9.2, and 14.7%, respectively. There were significant associations between the presence of disability and walking time for 6 m at the usual pace and at the fastest pace, and between the presence of disability and walking speed.ConclusionsWe established reference values for indices reflecting components of locomotive syndrome, and identified significant associations between walking ability and disability.     

Differential mechanisms underlie the regulation of serotonergic transmission in the dorsal and median raphe nuclei by mirtazapine: a dual probe microdialysis study

Rationale

Blockade of α₂ adrenoceptors and histamine H₁ receptors plays important roles in the antidepressant and hypnotic effects of mirtazapine.

Objectives

However, it remains unclear how mirtazapine’s actions at these receptors interact to affect serotonergic transmission in the dorsal (DRN) and median (MRN) raphe nuclei.

Method

Using dual-probe microdialysis, we determined the roles of α₂ and H₁ receptors in the effects of mirtazapine on serotonergic transmission in the DRN and MRN and their respective projection regions, the frontal (FC) and entorhinal (EC) cortices.

Results

Mirtazapine (<30 μM) failed to alter extracellular serotonin levels when perfused alone into the raphe nuclei, but when co-perfused with a 5-HT_1A receptor antagonist, mirtazapine increased serotonin levels in the DRN, MRN, FC, and EC. Serotonin levels in the DRN and FC were decreased by blockade and increased by activation of H₁ receptors in the DRN. Serotonin levels in the MRN and EC were not affected by H₁ agonists/antagonists perfused in the MRN. The increase in serotonin levels in the DRN and FC induced by DRN H₁ receptor activation was attenuated by co-perfusion with mirtazapine. Furthermore, the increase in serotonin levels (DRN/FC) induced by DRN α₂ adrenoceptor blockade was attenuated by concurrent DRN H₁ blockade, whereas the increase in serotonin levels (MRN/EC) induced by MRN α₂ adrenoceptor inhibition was unaffected by concurrent MRN H₁ receptor blockade.

Conclusion

These results suggest that enhanced serotonergic transmission resulting from α₂ adrenoceptor blockade is offset by subsequent activation of 5-HT_1A receptors and, in the DRN but not MRN, H₁ receptor inhibition. These pharmacological actions of mirtazapine may explain its antidepressant and hypnotic actions.     

Measurement of Blood Hematocrit Inside the Magnetically Suspended Centrifugal Pump Using an Optical Technique: Application to Assessment of Pump Flow

To measure blood hematocrit inside the magnetically suspended centrifugal pump, we have performed both forward and backward light scattering measurements using a specially designed optical cell. In the forward scattering measurement, an optical fiber was used to guide the near infrared light at 780 nm into a 250 microns gap region, and the light that forward scattered toward a detector fiber was measured using a phototransistor. The light intensity decreased exponentially with an increase in the hematocrit to around 20%. The forward scattering method suffered from sensitivity at the hematocrit levels around 25-45% due to the diffusion effect. By making the optical path length larger than several millimeters, the sensitivity of the forward scattering method in terms of hematocrit change can be improved. In the back scattering method, however, better sensitivity in terms of hematocrit change from 0-50% was obtained. By making the optical fiber separation distance less than 1 mm, the system will measure the first order back scattering from the shallow layer while, by making the fiber separation distance larger than several millimeters, the system will primarily measure the diffuse reflectance from the deeper layer. Both approaches will yield sensitive optical intensity change in terms of the physiological hematocrit range.     

Development of Terumo implantable left ventricular assist system (T-ILVAS) with a magnetically suspended centrifugal pump

The research group of Terumo, NTN, and the Setsunan University have been developing an implantable left ventricular assist system (T-ILVAS) featuring a centrifugal blood pump with a magnetically suspended impeller (MSCP). The present study describes recent progress in the development of the T-ILVAS, focusing on ex vivo and in vivo evaluations of the prototype MSCP. The MSCP is composed of four parts: a magnetic bearing, an impeller, a housing, and a DC burshless motor. The impeller is suspended by a magnetic bearing, thus providing contact-free rotation of the impeller inside the pump. The prototype MSCP was placed paracorporeally in three sheep and implanted intrathoracically in two sheep to evaluate its long-term durability and nonthrombogenicity. One sheep implanted ex vivo with the paracorporeal MSCP (Model I) survived for 864 days without any mechanical failure or thromboembolic complications, and with negligible hemolysis. The implantable Model II pump was evaluated ex vivo in two sheep and intrathoracically implanted in one sheep. These experiments were terminated 70, 79, and 17 days after implantation due to mechanical failure caused by blood leakage through the intrahousing connector of the Model II pump. However, there was no intradevice thrombus formation in any of the retrieved pumps. The dual connector system was then introduced to the Model II pump (the modified Model II), and the pump was intrathoracically implanted in a sheep. The sheep survived for more than 14 months without major complications, and the study is being continued. The preliminary chronic animal experiments demonstrated improved durability and nonthrombogenicity of the MSCP, with a low hemolysis rate for up to 864 days. Thus, the MSCP has significant potential for longterm application as an implantable circulatory assist system. Further developments toward a totally implantable system, including an implantable controller and a transcutaneous energy/information transfer system, are under way.     

Fluorescence detection of biotin using post-column derivatization with OPA in high performance liquid chromatography

A sensitive and selective high-performance liquid chromatographic method with post-column derivatization, using o-phthalaldehyde (OPA) and 3-mercaptopropionic acid (3-MPA), is described for the determination of biotin in pharmaceutical preparations. The use of 3-MPA gives intense fluorescent derivative and improves the stability of biotin fluorophore towards oxidation to the picomole level. The fluorophore was detected at 453 nm (excitation at 342 nm). The calibration graph was linear for 20–200 ng per injection. The detection limit of biotin under these conditions was about 10 ng per injection. The RSDs were 1.9–3.4%. This method could be applied to pharmaceutical preparations without interference of other compounds.