The kelvin redefinition and its mise en pratique

In 2018, it is expected that there will be a major revision of the International System of Units (SI) which will result in all of the seven base units being defined by fixing the values of certain atomic or fundamental constants. As part of this revision, the kelvin, unit of thermodynamic temperature, will be redefined by assigning a value to the Boltzmann constant k. This explicit-constant definition will define the kelvin in terms of the SI derived unit of energy, the joule. It is sufficiently wide to encompass any form of thermometry. The planned redefinition has motivated the creation of an extended mise en pratique ('practical realization') of the definition of the kelvin (MeP-K), which describes how the new definition can be put into practice. The MeP-K incorporates both of the defined International Temperature Scales (ITS-90 and PLTS-2000) in current use and approved primary-thermometry methods for determining thermodynamic temperature values. The MeP-K is a guide that provides or makes reference to the information needed to perform measurements of temperature in accord with the SI at the highest level. In this article, the background and the content of the extended second version of the MeP-K are presented.

Ballistocardiogram of baby during sleep

Ballistocardiogram (BCG), which displays the mechanical activity of heart, has been a subject of interest for several years due to its advantages in taking unobtrusive physiological measurements. In the field of sleep science, researchers actively study sleep architecture and clinically apply various sleep-related conditions through BCG-derived biological information such as the heartbeat, respiration and body movements of subjects. However, most of these studies have involved only adults. This area of research may be even more important with babies to monitor their biological signals without confinement. For this reason, we developed a physiological signal monitoring bed for baby by using a load cell. Heartbeat and respiration information was assessed with average respective performance errors of 1.53% and 2.53% compared to commercial equipment. The results showed the possibility of applying BCG technology to baby. Therefore, we expect that BCG-derived signals can be extensively applied to analyze sleep architecture and clinical applications in baby as they are with adults.

EBV-positive diffuse large B-cell lymphoma in young adults: is this a distinct disease entity?

BACKGROUND

Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) of the elderly is defined only in adults older than 50 years. However, EBV-positive DLBCL can affect younger patients. We investigated the prevalence, clinical characteristics and survival outcomes of EBV-positive DLBCL in young adults.

PATIENTS AND METHODS

We analyzed patients with de novo DLBCL who were registered in the Samsung Medical Center (SMC) retrospective lymphoma cohort and prospective SMC Lymphoma Cohort Study I (ClinicalTrials.gov: NCT00822731).

RESULTS

A total of 571 cases were included in the analysis. The prevalence of EBV positivity was 6.7% (13/195) and 9.3% (35/376) in the young group (≤50 years) and in the elderly group (>50 years), respectively. EBV status was closely associated with unique unfavorable clinical characteristics [older age, more advanced stage, two or more sites of extranodal involvement, higher International Prognostic Index (IPI), and age-adjusted IPI risk] only in the elderly group. Poor prognostic impact of EBV positivity on overall survival was observed only in the elderly group [hazard ratio (HR) 2.86; 95% confidence interval (CI) 1.83-4.47; P < 0.001], but not in the young group (HR 1.17; 95% CI 0.35-3.89; P = 0.801).

CONCLUSION

A substantial proportion of EBV-positive DLBCL of the elderly can occur in young adults. EBV positivity of DLBCL in young adults was not associated with unfavorable clinical characteristics or worse outcomes. We suggest that EBV-positive DLBCL should not be confined only in the elderly and 'EBV-positive DLBCL in young adults' needs to be considered as a clinically distinct disease entity. ClinicalTrials.gov: NCT02060435.

Therapeutic drug monitoring of mirtazapine in a routine outpatient setting in Asian psychiatric patients

INTRODUCTION

Mirtazapine is an antidepressant that acts by enhancing serotonergic and noradrenergic neurotransmission. This study aimed to evaluate mirtazapine pharmacokinetic data from Korean psychiatric patients and to identify the potential factors affecting its steady-state concentration.

METHODS

A total of 337 samples of steady-state mirtazapine concentrations from 188 adult psychiatric outpatients were retrospectively evaluated. Serum mirtazapine concentrations were measured by high-performance liquid chromatography-tandem mass spectrometry.

RESULTS

Median mirtazapine concentration was 43.6 μg/L (164.37 nmol) at a daily dosage range of 7.5-60 mg. At the steady state, mirtazapine dose had a positive correlation with the drug concentration. Mean concentration-to-dose (C/D) ratio was 1.48 μg/L/mg/day (5.58 nmol/mg/day), which was higher than that in a previous study in Caucasian subjects. Age and paroxetine co-medication were positively associated with C/D ratio. Initial mirtazapine concentration and C/D ratio did not show an association with responsiveness in depressive patients.

DISCUSSION

This study presented the therapeutic drug monitoring data for mirtazapine and pharmacokinetic variations of mirtazapine in an Asian population. A further study could be helpful for clinical decision making based on the characteristics of patients.