Volume ratio and distribution rate in patients with orthostatic vertigo/dizziness using MR imaging: a comparison with vertiginous diseases.

BACKGROUND: Orthostatic dizziness/vertigo (ODV) is characterized by lightheadedness owing to postural changes. AIMS/OBJECTIVES: To measure the endolymphatic space (ELS)/total fluid space (TFS) volume ratio and the distribution rate of endolymphatic fluid (ELF) of patients with ODV and compare them with those of control subjects (CS). MATERIALS AND METHODS: This study included 22 patients (44 ears) with ODV and 52 controls (104 ears, CS). The ELS/TFS volume ratio (%) and distribution rate (%) of the inner ear components were measured using 3-dimensional magnetic resonance imaging. RESULTS: In the ODV group, the mean ELS/TFS volume ratios of the cochlea, vestibule, and semi-circular canals (SCCs) were 12.1%, 18.6%, and 18.1%, respectively; the mean ELS distribution rates for the cochlea, vestibule, and SCCs were 27.3%, 26.2%, and 46.6%, respectively. The ELS distribution rate of the vestibule was significantly lower (p < .01) and the ELS distribution rate of the SCCs was significantly higher in the ODV than in the CS group (p < .01). CONCLUSIONS AND SIGNIFICANCE: The ELS distribution rate in the vestibule + SCCs among patients with ODV did not differ from that in the CS; ELF in the vestibule moved to the SCCs, and a large amount of ELF was distributed only in the SCCs.

Consideration of Fractional Distribution Parameter fd in the Chen and Gross Method for Tissue-to-Plasma Partition Coefficients: Comparison of Several Methods.

PURPOSE: The tissue-to-plasma partition coefficient (Kp) describes the extent of tissue distribution in physiologically-based pharmacokinetic (PBPK) models. Constant-rate infusion studies are common for experimental determination of the steady-state Kp,ss, while the tissue-plasma concentration ratio (CT/Cp) in the terminal phase after intravenous doses is often utilized. The Chen and Gross (C&G) method converts a terminal slope CT/Cp to Kp,ss based on assumptions of perfusion-limited distribution in tissue-plasma equilibration. However, considering blood flow (QT) and apparent tissue permeability (fupPSin) in the rate of tissue distribution, this report extends the C&G method by utilizing a fractional distribution parameter (fd). METHODS: Relevant PBPK equations for non-eliminating and eliminating organs along with lung and liver were derived for the conversion of CT/Cp values to Kp,ss. The relationships were demonstrated in rats with measured CT/Cp and Kp,ss values and the model-dependent fd for 8 compounds with a range of permeability coefficients. Several methods of assessing Kp were compared. RESULTS: Utilizing fd in an extended C&G method, our estimations of Kp,ss from CT/Cp were improved, particularly for lower permeability compounds. However, four in silico methods for estimating Kp performed poorly across tissues in comparison with measured Kp values. Mathematical relationships between Kp and Kp,ss that are generally applicable for eliminating organs with tissue permeability limitations necessitates inclusion of an extraction ratio (ER) and fd. CONCLUSION: Since many different types/sources of Kp are present in the literature and used in PBPK models, these perspectives and equations should provide better insights in measuring and interpreting Kp values in PBPK.

Magnetic resonance imaging of the endolymphatic space in patients with benign paroxysmal positional vertigo: volume ratio and distribution rate of the endolymphatic space.

BACKGROUND: Benign paroxysmal positional vertigo (BPPV) is the most common peripheral vestibular disease. It is characterised by sudden onset short lived vertigo triggered by sudden changes in head position relative to gravity. AIMS/OBJECTIVES: We aimed to perform a quantitative volumetric analysis of the inner ear endolymphatic space in patients with BPPV. MATERIAL AND METHODS: This study included 67 patients with BPPV and 50 control subjects (CS). The endolymphatic space/total fluid space volume ratio (%) and the distribution rate of the inner ear components in the endolymphatic space (%) were measured using three-dimensional magnetic resonance imaging. RESULTS: Differences in the endolymphatic space/total fluid space volume ratio of the inner ear, cochlea, vestibule, and semi-circular canals (SCCs) between the CS and BPPV groups were not significant. The endolymphatic space distribution rate of the vestibule in the BPPV group was significantly lower than that in the CS group, and the endolymphatic space distribution rate of SCCs in the BPPV group was significantly higher than that in the CS group. CONCLUSIONS AND SIGNIFICANCE: Extended endolymphatic space in patients with BPPV did not exist. The otoconia released from the damaged utricles were considered to move with the endolymphatic flow toward SCCs.

Magnetic resonance imaging of endolymphatic hydrops in patients with unilateral Meniere's disease: volume ratio and distribution rate of the endolymphatic space.

BACKGROUND: Endolymphatic hydrops (ELH), which is a pathological feature of Meniere's disease (MD), is characterized by an extended endolymphatic space (ELS). AIMS/OBJECTIVES: We aimed to perform a quantitative volumetric analysis of inner-ear ELH in patients with unilateral MD (uMD). MATERIAL AND METHODS: This study included 97 patients with definite uMD and 49 control subjects (CS). The ELS/total fluid space (TFS) volume ratio (%) and the distribution rate of the inner-ear components in the ELS (%) were measured using 3D magnetic resonance imaging and compared between patients with uMD and CS. RESULTS: Compared to CS, patients with uMD had significantly higher mean ELS/TFS volume ratios for inner-ear components. The mean distribution rate of the inner-ear components in the ELS was not significantly different between the two groups. CONCLUSIONS AND SIGNIFICANCE: In patients with uMD, ELH was noted to be spread throughout the entire inner ear and the endolymph was evenly distributed in the total ELS. These findings should be useful as a standard reference for further research.

Novel gridded descriptors of poincaré plot for analyzing heartbeat interval time-series.

A Poincaré plot is a return map that geometrically elucidates the progression of a time-series. It has frequently been used in heart rate variability analyses. However, algorithms for dedicatedly dissecting the shape of this geometrical plot are yet to be established. In this study, we proposed a gridded Poincaré plot by coarse-graining the original graph and using the newly proposed one, defined two novel measures, namely gridded distribution rate (GDR) and gridded distribution entropy (GDE). The GDR essentially represents the percentage of grids with points, while the GDE estimates the Shannon entropy of the grid weight; that is, the number of points in each grid. The performances of the two measures were examined using both theoretical data with known dynamics and experimental short-term RR interval time-series, and they were compared with several existing metrics. Simulation tests demonstrated that both the GDR and GDE could distinguish among different dynamics, while all the compared methods failed. The experimental results further indicated the ability of the GDR and GDE to differentiate healthy young people from healthy aged adults as well as distinguish healthy subjects from patients with coronary artery disease. Our results suggest that the proposed GDR and GDE may better characterize the Poincaré plot in terms of differentiating between varying dynamical regimes, and between human physiological or pathological conditions. Further studies are warranted to establish their feasibility in evaluating cardiovascular functions in clinical practice.

Investigation on Current Situation of Medicine Supply in Primary Health Care Institutions of Anhui Province / 中国药房

OBJECTIVE:To provide reference for improving the efficiency of medicine supply in primary health care institutions. METHODS:By stratified random sampling,6 counties of Dabie Mountains in Anhui province were selected as sample areas. Medicine purchase data of 143 primary health care institutions in 2015 were collected from Anhui provincial centralized purchase platform. Those data were analyzed in respects of purchase and distribution of National Essential Medicine,medicines of Anhui Province Essential Medicine List and cheap medicines. By stratified random sampling,12 primary health care institutions were selected for on-site interview. The reasons for medicine distribution and insufficient distribution were investigated. RESULTS:The rate of medicine distribution in the sample areas was 82.27%,and the rate of essential medicine distribution was more than 80%. Ratio of purchase amount for national essential medicines and medicines of Anhui Province Essential Medicine List were all up to standard in different types of primary health care institutions. The rate of cheap medicine distribution was in low level(only 80%). The distribution rate had great difference in the primary health care institutions and different areas;the highest rate of medicine distribution reached 99.86%,and the lowest was only 46.18%. The results of on-site investigation showed that main reasons for insufficient distribution were the divided area distribution model had a certain influence on the market competitiveness of the distribution enterprises,and distribution enterprises strength had huge differences. CONCLUSIONS:The primary health care institutions have high awareness of National Essential Medicine System in Dabie Mountains of Anhui Province;purchase rate and overall distribution rate of essential medicine are also high. There are great differences in distribution efficiency among different areas and health care institutions,and some health care institutions cannot distribute medicine in time with full capacity. It is suggested to conduct"two-receipt system"of medicine distribution,perfect medicine distribution enterprise supervision system, establish medicine circulation information platform and lead cheap medicine supply guarantee by government,etc. Those measures can guarantee the accessibility and selectivity of the masses to essential medicines in grass-roots areas.