Development of a new tracer-encapsulated solid pellet injection system for more precise control of tracer-impurity-deposit location in LHD

A new tracer-encapsulated solid pellet (TESPEL) injection system has been developed additionally for the LHD heliotron. This system has three-dimensionally bended guide tubes, which allows us to inject the TESPEL obliquely on a poloidal cross-section of the LHD plasma. Consequently, this system enables us to control a tracer-impurity-deposited location more precisely. Moreover, this system can make it possible for the tracer impurity to be deposited even only inside the ergodic region (outside a last closed flux surface of the LHD plasma). A stereoscopic fast camera system has been also developed for capturing a three-dimensional TESPEL trajectory.

Calibrations of the LHD Thomson scattering system

The Thomson scattering diagnostic systems are widely used for the measurements of absolute local electron temperatures and densities of fusion plasmas. In order to obtain accurate and reliable temperature and density data, careful calibrations of the system are required. We have tried several calibration methods since the second LHD experiment campaign in 1998. We summarize the current status of the calibration methods for the electron temperature and density measurements by the LHD Thomson scattering diagnostic system. Future plans are briefly discussed.

Tracer-Encapsulated Solid Pellet (TESPEL) injection system for the TJ-II stellarator

A tracer-encapsulated solid pellet (TESPEL) injection system for the TJ-II stellarator was recently developed. In order to reduce the time and cost for the development, we combined a TESPEL injector provided by National Institute for Fusion Science with an existing TJ-II cryogenic pellet injection system. Consequently, the TESPEL injection into the TJ-II plasma was successfully achieved, which was confirmed by several pellet diagnostics including a normal-incidence spectrometer for monitoring a tracer impurity behavior.

Validations of calibration-free measurements of electron temperature using double-pass Thomson scattering diagnostics from theoretical and experimental aspects

This paper evaluates the accuracy of electron temperature measurements and relative transmissivities of double-pass Thomson scattering diagnostics. The electron temperature (T_e) is obtained from the ratio of signals from a double-pass scattering system, then relative transmissivities are calculated from the measured T_e and intensity of the signals. How accurate the values are depends on the electron temperature (T_e) and scattering angle (θ), and therefore the accuracy of the values was evaluated experimentally using the Large Helical Device (LHD) and the Tokyo spherical tokamak-2 (TST-2). Analyzing the data from the TST-2 indicates that a high T_e and a large scattering angle (θ) yield accurate values. Indeed, the errors for scattering angle θ = 135° are approximately half of those for θ = 115°. The method of determining the T_e in a wide T_e range spanning over two orders of magnitude (0.01-1.5 keV) was validated using the experimental results of the LHD and TST-2. A simple method to provide relative transmissivities, which include inputs from collection optics, vacuum window, optical fibers, and polychromators, is also presented. The relative errors were less than approximately 10%. Numerical simulations also indicate that the T_e measurements are valid under harsh radiation conditions. This method to obtain T_e can be considered for the design of Thomson scattering systems where there is high-performance plasma that generates harsh radiation environments.

Semi-mechanistic autoinduction model of midazolam in critically ill patients: population pharmacokinetic analysis

WHAT IS KNOWN AND OBJECTIVE

Midazolam (MDZ) is commonly used for sedating critically ill patients. The daily dose required for adequate sedation increases in increments over 100 h after administration. The objectives of this study were to characterize the MDZ pharmacokinetics in critically ill patients and to describe the phenomenon of increasing daily dose by means of population pharmacokinetic analysis.

METHODS

Data were obtained from 30 patients treated in an intensive care unit. The patients received MDZ intravenously as a combination of bolus and continuous infusion. Serum MDZ concentration was assayed by high-performance liquid chromatography. Population pharmacokinetic analysis was performed using the NONMEM software package. The alteration of clearance unexplained by demographic factors and clinical laboratory data was described as an autoinduction of MDZ clearance using a semi-mechanistic pharmacokinetic-enzyme turnover model.

RESULTS AND DISCUSSION

The final population pharmacokinetic model was a one-compartment model estimated by incorporating a semi-mechanistic pharmacokinetic-enzyme turnover model for clearance, taking autoinduction into account. A significant covariate for MDZ clearance was total bilirubin. An increase in total bilirubin indicated a reduction in MDZ clearance. From simulation using the population pharmacokinetic parameters obtained in this study, MDZ clearance increased 2·3 times compared with pre-induced clearance 100 h after the start of 12·5 mg/h continuous infusion.

WHAT IS NEW AND CONCLUSION

Autoinduction and total bilirubin were significant predictors of the clearance of MDZ in this population. Step-by-step dosage adjustment using this population pharmacokinetic model may be useful for establishing a MDZ dosage regimen in critically ill patients.

Modified total meso-pancreatoduodenum excision with pancreaticoduodenectomy as a mesopancreatic plane surgery in borderline resectable pancreatic cancer

BACKGROUND

A superior mesenteric artery (SMA)-first approach has been considered to be an efficient technique in pancreaticoduodenectomy when the SMA is a factor of borderline resectable pancreatic head cancer (BRPHC). However, this excellent procedure has limitations in terms of tumor resection with an intact coverage including the pancreatic tumor and the tumor-draining lymphovascular systems and the ability to achieve a complete regional lymphadenectomy.

METHODS

A modified mesenteric plane procedure has been developed that provides improved regional lymphadenectomy and permits adjustment of the surgical approach, which is based on the direction of the tumor infiltration.

RESULTS

Of 55 patients taken to surgery, 19 had peritoneal dissemination and/or liver metastasis at staging laparoscopy, and the procedure revealed tumor infiltration to the SMA and/or hepatic artery (HA) in 4 patients. Finally, 32 patients with BRPHC have undergone the procedure between April 2009 and June 2015. Twenty-four of 32 patients (75.0%) had negative resection margins, and the median number of lymph nodes harvested was 34. Lymph nodes around the SMA tested positive for metastasis in 13 patients (40.6%), and those around the HA tested positive for metastasis in 7 patients (21.9%). Complications occurred in 14 patients (43.7%), with no perioperative mortality. Overall survival rates were 65.3% at 1 year and 35.2% at 3 years.

CONCLUSIONS

Short-term results with the procedure may encourage surgical management for BRPHC.

Kidney Transplantation, Cardiovascular Risk, and Long-Term Dialysis in Japan

BACKGROUND

The waiting time for deceased-donor kidney-only transplantations in Japan is long. Herein, we assessed the effect of length of dialysis on the outcomes of these patients.

METHODS

We divided patients into 2 groups based on length of dialysis (Group A, <15 years, and Group B, ≥15 years), and compared the background and outcomes after kidney transplantation.

RESULTS

Group A included 210 patients and Group B included 35 patients. In Group B, 20% of transplants were from living donors. Patient age (P = .017) and the hepatitis C infection rate (P = .018) were significantly higher in Group B, whereas hypertension (P = .011), diabetes (P = .041), and ABO-incompatibility rates (P = .015) were significantly higher in Group A. The 5- and 10-year survival rates were 97.0% and 95.4%, respectively, in Group A and 97.1% and 97.1%, respectively, in Group B. The 5- and 10-year graft survival rates were 95.4% and 84.8%, respectively, in Group A and 97.1% and 73.1%, respectively, in Group B. There were no significant differences between the groups in patient survival (P = .74) and graft survival (P = .72). The 5- and 10-year cardiovascular event-free survival rates were 95.9% and 92.4%, respectively, in Group A and 88.6% and 76.8%, respectively, in Group B. Cardiovascular event-free survival was significantly higher in Group A (P = .038). Cox stepwise multivariate analysis indicated that length of dialysis was a significant predictor of cardiovascular events (hazard risk, 1.007; range, 1.001-1.012; P = .012).

CONCLUSION

The prognosis after kidney transplantation is promising even after a long length of dialysis, although evaluation of the cardiovascular risk is needed in these cases.

Early optimization of antimicrobial therapy improves clinical outcomes of patients administered agents targeting methicillin-resistant Staphylococcus aureus

WHAT IS KNOWN AND OBJECTIVE

Antimicrobial stewardship is required to ensure the appropriate use of antimicrobials. However, no reports have been published on clinical outcomes of implementation of antimicrobial stewardship in patients receiving pathogen-specific antibiotics.

METHOD

To evaluate the clinical outcomes of patients who received drugs, we conducted a single-centre, retrospective study of the effects of an antimicrobial stewardship programme targeting methicillin-resistant Staphylococcus aureus (MRSA).

RESULTS

The time to administer effective antimicrobials was significantly (median number of days, 3 before vs. 0 after, P < 0·001) shortened, and the rate of de-escalation was significantly elevated (47·1% vs. 96·2%, P < 0·001) after implementation of daily review. The 60-day clinical failure associated with Gram-positive bacterial infection was significantly reduced (33·3% vs. 17·6%, P = 0·007) after intervention.

WHAT IS NEW AND CONCLUSIONS

Daily review of administration of antimicrobials targeting MRSA was highly effective in improving clinical outcomes by optimizing early antimicrobial therapy.

Analysis of factors for poor activated partial thromboplastin time control after dabigatran administration

In this study, we compared patients whose activated partial thromboplastin time (APTT) was prolonged excessively with those whose APTT was controlled within the normal range after dabigatran administration. We analyzed the factors for the APTT prolongation. We divided the patients into two groups: those whose APTTs prolonged to more than 65 s and those whose APTTs were less than 65 s after dabigatran administration. There were 130 patients from March 2011 to July 2013, and we analyzed the background features and laboratory data of these patients. Results showed that there were no significant differences in the patients' background and laboratory data except for the high-density lipoprotein cholesterol (HDL-C) level. However, details of the relationship between the APTT prolongation and the HDL-C level are currently unknown. We hypothesize that the reason for the APTT prolongation is the variability in such parameters as the time of blood drawing, internal time of dabigatran, individual variability, and blood concentration. Therefore, we consider that these parameters need to be carefully evaluated even if APTT does not show prolongation.