Improvement of muscle quality assessed using the phase angle is influenced by recovery of knee extension strength in patients with hip fractures

BACKGROUND AND AIMS

Studies reported that knee extension strength on the operated side in patients with hip fractures was not recovered to the level on the non-operated side 6 months after surgery or later. In a cross-sectional study, we revealed that a reduction in isometric knee extension muscle strength on the operated side in patients with hip fractures approximately 6 months after surgery was associated with not only a reduction in skeletal muscle mass but also a reduction in muscle quality, characterized by a reduction in the phase angle (PhA). Furthermore, the mechanisms of knee extension strength improvement can be clarified in more detail using the minimal significant change as the index of recovery. However, no longitudinal studies have examined the factors for knee extension strength improvement based on the minimal significant change in patients with hip fractures 6 months after surgery. This study aimed to longitudinally examine the factors influencing the recovery of knee extension strength based on the minimal significant change in patients with hip fractures between 2 weeks and approximately 6 months after surgery.

METHODS

In this study, the outcomes used were basic and medical information, PhA, skeletal muscle index (SMI), pain, one-leg standing time, movement control during one-leg standing, and walking speed. For PhA, SMI, pain, one-leg standing time, movement control during one-leg standing, and walking speed, the amount of change was calculated by subtracting the data at 2 weeks from the data at 6 months. Group classification was determined by dividing the patients into two groups using a previous study as a reference: recovery group if the knee extension strength value approximately 6 months after surgery minus that 2 weeks after surgery was ≥3.3 kgf and non-recovery group if the value was <3.3 kgf. Logistic regression analysis was performed to explore the association between the recovery and non-recovery groups.

RESULTS

The recovery group contained 55 patients, while the non-recovery group comprised 35 patients. The only significant factor associated with knee extension muscle strength in the recovery group was the amount of change in PhA. The odds ratio for the amount of change in PhA was 2.26. The discrimination rate of the model was 62.5%.

CONCLUSIONS

Our results suggest that recovery of knee extension strength in patients with hip fractures after surgery was mainly because of improvements in muscle quality, not improvements in muscle mass or pain.

Not only muscle mass but also muscle quality is associated with knee extension muscle strength in patients with hip fractures

Our results revealed that the decrease in isometric knee extension muscle strength on the operated and nonoperated sides in patients with hip fractures was associated with not only a decrease in skeletal muscle mass but also a decrease in muscle quality, characterized by a decreased PhA.

PURPOSE

This study aimed to assess the relationship between isometric knee extension muscle strength on the operated or nonoperated sides and PhA in patients with hip fractures at approximately 6 months postoperatively.

METHODS

This study was a cross-sectional study. Skeletal muscle index (SMI), PhA, knee extension muscle strength on the operated and nonoperated sides, and other physical function variables were assessed at approximately 6 months postoperatively. To identify predictors of knee extension muscle strength on the operated and nonoperated sides, hierarchical multiple regression analysis was performed.

RESULTS

A total of 90 patients with hip fractures were included (mean age, 80.1 ± 6.9 years). SMI (0.45) and PhA on the operated side (0.27) were the significant associated factors extracted for isometric knee extension muscle strength on the operated side (standardized partial regression coefficients), independent of age, sex, and body mass index (BMI). Movement control during one-leg standing on the nonoperated side (0.26), SMI (0.32), and PhA on the nonoperated side (0.40) were the significant associated factors extracted for isometric knee extension muscle strength on the nonoperated side, independent of age, sex and BMI.

CONCLUSIONS

Our results revealed that the decrease in isometric knee extension muscle strength on the operated and nonoperated sides in patients with hip fractures at approximately 6 months postoperatively was associated with not only a decrease in skeletal muscle mass but also a decrease in muscle quality, characterized by a decreased PhA.

Structures, Thermal Properties, and Reactivities of Cationic Rh-cod Complexes in Solid State (cod = 1,5-Cyclooctadiene)

Cationic rhodium complexes with 1,5-cyclooctadiene (cod) ligands are important organometallic compounds that are useful as precatalysts; however, their solid-state structures and thermal properties have not been adequately investigated. In this study, we synthesized [Rh(cod)L]X (L = cod, C6H6, PhMe; X = SbF6, (FSO2)2N (= FSA), CF3BF3, CB11H12) and investigated their phase behaviors, crystal structures, and reactivities. The phase transitions of these salts result in disordered solid-state structures. Moreover, the structural disorder increases with a decrease in the cation symmetry in the SbF6 salts; [Rh(cod)(PhMe)]SbF6 exhibits a rotator phase, and the cations in other salts exhibit a dynamic rotational disorder. In contrast, a lower crystal symmetry with less cation disorder is observed for FSA salts. The thermal stabilities and reactivities of these salts were further investigated. FSA salts with arene ligands produce anion-coordinated complexes upon melting, and SbF6 salts with arene ligands produce [Rh(cod)L'2]SbF6 (L' = MeCN and SMe2) via an in situ single-crystal-to-single-crystal ligand-exchange reaction.

Frailty in elderly patients with acute heart failure increases readmission

BACKGROUND

The readmission rate of heart failure (HF) patients has not decreased during the past few years.

OBJECTIVES

The purpose of this study was to examine whether factors such as left ventricular ejection fraction (LVEF) and frailty are associated with readmission and number of readmissions in HF patients.

METHODS

First, a propensity score matching method was used to adjust for confounding factors for readmission. Cox regression analysis was conducted to determine the factors that influenced readmission. Finally, multiple regression analysis was conducted to determine the factors that influenced the number of readmissions. The independent variables were basic and medical information, physical structure, physical functions, and activity for both Cox regression analysis and multiple regression analysis.

RESULTS

After matching based on the propensity score, 18 out of 18 (100.0%) patients in the readmission group (age: 85.0 ± 6.9 years, female rate: 50.0%, body mass index: 21.7 ± 3.4 kg/m²) and 18 out of 51 (35.3%) patients in the nonreadmission group (age: 84.3 ± 8.6, female rate: 50.0%, body mass index: 21.8 ± 4.5 kg/m²) were eligible for analysis. Cox regression analysis (hazard ratios) showed that sex (0.16), geriatric nutritional risk index (1.02), and degree of frailty (11.44) were extracted as significant factors. Multiple regression analysis (standardized regression coefficients) showed that the estimated glomerular filtration rate (-0.40), LVEF (-0.32), and degree of frailty (0.29) were extracted as significant factors.

CONCLUSION

Our results suggest that frailty is important to reduce the readmission rate and number of readmissions of the acute HF patients.

Reduced upper and lower limb muscle strengths without reduced skeletal muscle in elderly patients with heart failure

Objective: This study aimed to characterize the muscle strength and skeletal muscle mass of patients with heart failure by investigating hand-grip strength, five times sit-to-stand (5STS) results, and skeletal muscle mass index (SMI). Materials and Methods: Muscle strength was assessed based on hand-grip strength and 5STS, while skeletal muscle mass was assessed using a bioelectrical impedance analyzer. Hierarchical logistic regression analysis was performed to explore the association between patients with heart failure and healthy elderly individuals. Results: Hierarchical logistic regression analysis was performed to examine the muscle strength and skeletal muscle mass characteristics in patients with heart failure. Hand-grip strength and 5STS responses but not SMI outcomes differed significantly between the two groups. The results of the hierarchical logistic regression analysis revealed that the hand-grip strength and 5STS were significant predictors of heart failure. The odds ratios for hand-grip strength and 5STS were 1.44 and 0.53, respectively. Conclusion: Our results suggested that upper and lower limb muscle strengths (handgrip strength and 5STS) in elderly patients with heart failure worsened significantly without a decrease in skeletal muscle mass.

New Q and V-band ECE radiometer for low magnetic field operation on LHD

To meet the demand for information on electron temperature fluctuations in low magnetic field experiments in the Large Helical Device (LHD), a new ECE radiometer covering the Q and V bands has been installed. Combination mirrors are installed in the vacuum vessel to focus the beam and efficiently propagate the radiated electron cyclotron waves. Notch filters are used to eliminate stray light from the gyrotron, and a 32-channel heterodyne radiometer is constructed using a filter bank system. As a result, oscillations of electron temperature and both electromagnetic and electrostatic fluctuations were successfully observed.

Movement control during one-leg standing is important for the bone mineral density maintenance or improvement

INTRODUCTION

Both hip fracture and bone mineral density (BMD) decline on the non-fractured side are more likely to occur within 1 year. However, there are no longitudinal study reports on the factors associated with BMD maintenance or improvement within the first year after hip fracture. This study aimed to investigate the factors influencing the neck BMD maintenance or improvement in patients with hip fractures from within 2 weeks-6 months after surgery.

MATERIALS AND METHODS

Patients were hip fracture after surgery and were divided into two groups: Among neck BMD changes (6 months minus 2 weeks after surgery) were calculated. Based on among neck BMD change, patients were classified into the BMD maintenance or improvement (change ≥ 0) and the BMD decrease groups (change < 0). Propensity score matching was performed to adjust for confounding factors. To predict the factors affecting neck BMD, hierarchical logistic regression analysis was performed. The dependent variable was the BMD maintenance or improvement group and the BMD decrease group. The independent variables were basic and medical information, and physical functions.

RESULTS

The hierarchical logistic regression analysis results showed that movement control during one-leg standing affected femoral neck BMD independently from age, sex. The odds ratio for movement control during one-leg standing was 8.22. The discrimination rate of the model was 69.7%.

CONCLUSION

This study suggested that adequate movement control during one-leg standing is important to maintain or improve neck BMD.

Convergent neutral gas injection using supersonic gas puffing (SSGP) method for propellant feeding system in RF electric propulsion

A convergent gas feeding method is proposed to alleviate neutral gas depletion near the central plasma region in typical electrodeless radio-frequency (RF)/helicon plasma thrusters. To achieve further performance improvement, the SuperSonic Gas Puffing (SSGP) system is one of the methods that is expected to overcome the above-mentioned depletion and the density limit. This study discovered that the spatiotemporal profiles of the neutral pressure and the estimated gas diffusion angle vary depending on the SSGP gas feeding condition, i.e., the nozzle size, filling pressure, and the valve opening time. Convergent gas feeding is successfully conducted using the SSGP method in a vacuum. As a preliminary study, high-density plasma is also obtained in the vicinity of the gas injection region using the developed SSGP system. The effects of the gas feeding position and an external divergent magnetic field on the plasma density are investigated. A suitable gas feeding position/region exists for plasma generation using the RF/helicon plasma thruster.

Physical Functions and Comorbidity Affecting Collapse at 4 or More Weeks after Admission in Patients with Osteoporotic Vertebral Fractures: A Prospective Cohort Study

Study Design

A prospective cohort study.

Purpose

This study aimed to reveal physical functions and comorbidity affecting collapse at ≥4 weeks after hospital admission of patients with osteoporotic vertebral fracture.

Overview of Literature

Only a few studies have investigated the influence of physical function and activity on collapse in patients with osteoporotic vertebral fractures.

Methods

This prospective cohort study analyzed patients with osteoporotic vertebral fractures admitted to the hospital between March 2018 and October 2019. Logistic regression analysis was performed to explore the predictors of vertebral collapse at >4 weeks after admission. Model 1 used basic medical information and physical functions at admission; model 2 used basic medical information and physical function and activity at >4 weeks after admission.

Results

In the model 1 results of logistic regression analysis, cardiovascular disease (odds ratio [OR], 12.27; 95% confidence interval [CI], 1.28–117.91) was extracted as a factor affecting vertebral collapse at ≥4 weeks after admission. In the model 2 results of logistic regression analysis, cardiovascular disease (OR, 34.57; 95% CI, 2.53–471.74), movement control during one leg standing at 4 weeks (OR, 7.25; 95% CI, 1.36–38.71), and Pain Catastrophizing Scale score at 4 weeks (OR, 1.11; 95% CI, 1.01–1.21) were extracted as factors affecting vertebral collapse at ≥4 weeks after admission.

Conclusions

Our results indicate that physical functions and comorbidity affect collapse at ≥4 weeks after admission in patients with osteoporotic vertebral fractures.

Association between movement control during one-leg standing and femoral BMD in patients with hip fractures

INTRODUCTION

Prior studies have focused only on the temporal component of one-leg standing, no reports have examined the relationship between the qualitative components of one-leg standing and femoral BMD. Thus, this study investigated whether quality (i.e., movement control) of one-leg standing also associated femoral BMD.

MATERIALS AND METHODS

A total of 80 patients with unilateral hip fracture were included in a cross-sectional study. Basic and medical information and physical functions including movement control during one-leg standing were assessed at admission and 2 weeks after surgery, respectively. Hierarchical multiple regression analysis was performed to identify predictors of femoral BMDs on the non-fractured side. Dependent variables included femoral neck and total hip BMDs in models 1 and 2, respectively.

RESULTS

Hierarchical multiple regression analysis (standardized partial regression coefficients) in model 1 identified age (- 0.18), sex (0.38), body mass index (BMI) (0.41), movement control during one-leg standing on the non-fractured side (0.19), and life-space assessment (0.17) as factors associating femoral neck BMD. Meanwhile, hierarchical multiple regression analysis (standardized partial regression coefficients) in model 2 identified age (- 0.12), sex (0.36), BMI (0.37), and movement control during one-leg standing on the non-fractured side (0.25) as factors associating total hip BMD. The coefficients of determination adjusted for degrees of freedom (R²) were 0.529 and 0.470 for models 1 and 2, respectively.

CONCLUSION

Our results suggest that improving movement control during one-leg standing may be important for maintaining and improving femoral BMD on the non-fractured side.

Factors Affecting Quality of Life at Discharge among Patients with Osteoporotic Vertebral Fractures

OBJECTIVES

This study aimed to identify factors, including physical functions and activities that affect quality of life (QOL) at discharge among patients with osteoporotic vertebral fractures.

METHODS

Patients with osteoporotic vertebral fractures were included in our prospective cohort study. Multiple regression analysis was performed to determine the predictors of QOL at discharge using two models: model 1, basic medical information and physical functions at admission, and model 2, basic medical information, physical function, and activity after 4 weeks of admission.

RESULTS

Multiple regression analysis (standard partial regression coefficients) using model 1 identified L2 to L4 bone mineral density (-0.2), Visual Analog Scale for pain during activity at admission (-0.31), and Revised Hasegawa Dementia Scale (HDS-R) score at admission (0.64) as factors affecting QOL at discharge. Multiple regression analysis using model 2 identified HDS-R at admission (0.64), Pain Catastrophizing Scale score at 4 weeks (-0.34), and knee extension muscle strength at 4 weeks (0.28) as factors affecting QOL at discharge.

CONCLUSIONS

Our results suggest that if patients have high bone mineral density, intense pain, and low cognitive function at admission, then low QOL at discharge will be predicted; however, improvement of pain catastrophizing and knee extension muscle strength during first the 4 weeks of admission may be able to improve QOL at discharge. Because patients in this study were Japanese only, it is important to exercise caution when applying our results to other populations.

Extremely small-diameter, high-density, radio frequency, plasma sources and central gas feeding for next-generation electrodeless plasma thrusters

Radio frequency (RF) waves including helicon waves can readily produce high-electron-density (n_e up to 10¹³ cm^-3) plasmas with a broad range of external operating parameters. Various featured RF and helicon sources in a wide range of scales are suitable for plasma propulsion schemes. Electrodeless RF plasmas have no direct contact between electrodes and antennas, which enables long-life operation. However, one of the crucial problems is to reduce the plasma size for future applications in nano- and pico-satellites. Diagnostics of the plasma parameters in a small area should also be improved. Furthermore, to increase plasma performance, it is important to consider the radial electron density (n_e) profile with an increasing upper limit, observed in high-density helicon sources due to the depletion of neutrals. This problem may be controlled by the location of neutral gas feeding and knowledge of the gas pressure distribution. Here, production of RF plasmas, with extremely small diameters from 3-mm down to 0.5-mm including 1-mm, was demonstrated, and characterization of n_e and the electron temperature was performed with a collisional radiative model. Finally, to improve plasma performance such as n_e and the thrust force, internal gas feeding was demonstrated using a developed Pirani gauge to measure neutral density.

Spatial measurement in rotating magnetic field plasma acceleration method by using two-dimensional scanning instrument and thrust stand

A two-dimensional scanning probe instrument has been developed to survey spatial plasma characteristics in our electrodeless plasma acceleration schemes. In particular, diagnostics of plasma parameters, e.g., plasma density, temperature, velocity, and excited magnetic field, are essential for elucidating physical phenomena since we have been concentrating on next generation plasma propulsion methods, e.g., Rotating Magnetic Field plasma acceleration method, by characterizing the plasma performance. Moreover, in order to estimate the thrust performance in our experimental scheme, we have also mounted a thrust stand, which has a target type, on this movable instrument, and scanned the axial profile of the thrust performance in the presence of the external magnetic field generated by using permanent magnets, so as to investigate the plasma captured in a stand area, considering the divergent field lines in the downstream region of a generation antenna. In this paper, we will introduce the novel measurement instrument and describe how to measure these parameters.

Development of 2-D horn-antenna millimeter-wave imaging device (HMID) for the plasma diagnostics

The two-dimensional (2-D) Horn-antenna Millimeter-wave Imaging Device (HMID) has been developed for the O-mode Microwave Imaging Reflectometry (O-MIR) in the Large Helical Device (LHD). The detectable frequency range of the HMID is 23-33 GHz, which corresponds to the cutoff electron density of 0.8-1.5 × 10¹⁹ m^-3 in the O-MIR. The HMID is a 2-D imaging device that improves on the horn-antenna mixer array, which had been developed for the X-mode MIR in the LHD. In the HMID, the signal (RF) wave from the horn antenna is transmitted to the microstrip line by the finline transmitter, and this is mixed by the double-balanced-mixer with the local oscillation wave that is fed by a coaxial cable. By using the HMID, the MIR optical system can be significantly simplified.

A 60-GHz interferometer with a local oscillator integrated antenna array for divertor simulation experiments on GAMMA 10/PDX

In conventional multichannel/imaging microwave diagnostics of interferometry, reflectometry, and electron cyclotron emission measurements, a local oscillator (LO) signal is commonly supplied to a receiver array via irradiation using LO optics. In this work, we present a 60-GHz interferometer with a new eight-channel receiver array, called a local oscillator integrated antenna array (LIA). An outstanding feature of LIA is that it incorporates a frequency quadrupler integrated circuit for LO supply to each channel. This enables simple and uniform LO supply to the receiver array using only a 15-GHz LO source and a coaxial cable transmission line instead of using an expensive 60-GHz source, LO optics, and a waveguide transmission line. The new interferometer system is first applied to measure electron line-averaged density inside the divertor simulation experimental module (D-module) on GAMMA 10/PDX tandem mirror device.

Theoretical study of a simple rotational-echo double-resonance NMR for homonuclear spin-1/2 pairs

We investigate theoretically intriguing aspects of a simple rotational-echo double-resonance (REDOR) NMR technique for homonuclear spin-1/2 pairs undergoing MAS. The simple technique sets Gaussian soft π pulses at every half MAS rotational period in the pulse sequence. The reduction in rotational echo amplitude (the REDOR echo reduction) is observed at the end of the evolution period te  = (n + 1)Tr, where Tr is a MAS rotational period. The exact average Hamiltonians for the homonuclear REDOR (hm-REDOR) technique are calculated by dividing the evolution period into four periods. We show theoretically and experimentally that the hm-REDOR technique produces the REDOR echo reductions for homonuclear spin-1/2 pairs. In addition, the theoretical results reveal that the REDOR echo reductions are independent of the chemical-shift difference, δ, under a simple condition of κ = δ/ωr  ≥ 6 and te  < 10 ⋅ (1/d'), where ωr is the sample spinning frequency and d' is the dipolar coupling constant expressed in Hz. We call this simple condition the master condition. This means that the REDOR echo reductions for a homonuclear spin-1/2 pair can be calculated under the master condition by considering only d' and ωr , which is the case for a heteronuclear spin pair. Finally, we demonstrate that four-phase cycling yields the multiple-quantum filtered hm-REDOR experiment, where the appearance of the REDOR echo reductions shows that the echo reductions are definitely attributable to the homonuclear dipolar interaction even if there is a slight unwanted effect from the recovered chemical-shift anisotropy in these reductions.

Validation experiment of a numerically processed millimeter-wave interferometer in a laboratory

We propose a new interferometer system for density profile measurements. This system produces multiple measurement chords by a leaky-wave antenna driven by multiple frequency inputs. The proposed system was validated in laboratory evaluation experiments. We confirmed that the interferometer generates a clear image of a Teflon plate as well as the phase shift corresponding to the plate thickness. In another experiment, we confirmed that quasi-optical mirrors can produce multiple measurement chords; however, the finite spot size of the probe beam degrades the sharpness of the resulting image.

Development of horn antenna mixer array with internal local oscillator module for microwave imaging diagnostics

A new antenna array is proposed in order to improve the sensitivity and complexity of microwave imaging diagnostics systems such as a microwave imaging reflectometry, a microwave imaging interferometer, and an electron cyclotron emission imaging. The antenna array consists of five elements: a horn antenna, a waveguide-to-microstrip line transition, a mixer, a local oscillation (LO) module, and an intermediate frequency amplifier. By using an LO module, the LO optics can be removed, and the supplied LO power to each element can be equalized. We report details of the antenna array and characteristics of a prototype antenna array.

Development of very small-diameter, inductively coupled magnetized plasma device

In order to miniaturize a high-density, inductively coupled magnetized plasma or helicon plasma to be applied to, e.g., an industrial application and an electric propulsion field, small helicon device has been developed. The specifications of this device along with the experimental results are described. We have succeeded in generating high-density (~10(19) m(-3)) plasmas using quartz tubes with very small diameters of 10 and 20 mm, with a radio frequency power ~1200 and 700 W, respectively, in the presence of the magnetic field less than 1 kG.

Development of 3D microwave imaging reflectometry in LHD (invited)

Three-dimensional (3D) microwave imaging reflectometry has been developed in the large helical device to visualize fluctuating reflection surface which is caused by the density fluctuations. The plasma is illuminated by the probe wave with four frequencies, which correspond to four radial positions. The imaging optics makes the image of cut-off surface onto the 2D (7 × 7 channels) horn antenna mixer arrays. Multi-channel receivers have been also developed using micro-strip-line technology to handle many channels at reasonable cost. This system is first applied to observe the edge harmonic oscillation (EHO), which is an MHD mode with many harmonics that appears in the edge plasma. A narrow structure along field lines is observed during EHO.

Simultaneous projection and detection system of four different frequencies for microwave imaging reflectometry in Large Helical Device

A simultaneous projection/detection system of four different frequencies for microwave imaging reflectometry (MIR) was developed for three-dimensional observation of electron density fluctuations in the Large Helical Device (LHD). The microwave with four frequency components at 60.410, 61.808, 63.008, and 64.610 GHz is projected in a continuous-wave mode to illuminate the target LHD plasma. A two-dimensional horn-antenna mixer array (2D HMA) receives the reflected wave from the plasma as well as the wave from the local oscillator operating at 55.800 GHz. The first intermediate frequency (IF) signals at 4.610, 6.008, 7.208, and 8.810 GHz were confirmed to be obtained by downconversion of these microwaves using the 2D HMA. Each of these first IF components is filtered from each other and downconverted again for the superheterodyne detection. It was confirmed that both the amplitudes and the phases of the detected signals reflect the fluctuations in LHD plasmas.

Development of electron cyclotron emission imaging system on Large Helical Device

A combined system of microwave imaging reflectometry and electron cyclotron emission (ECE) imaging has been developed for the Large Helical Device. This system includes a wide-band two-dimensional horn-antenna mixer array (HMA). The HMA consists of horn antennas, waveguides, mixers, and intermediate frequency circuits. The frequency response of the HMA is between 50 and 110 GHz. The ECE signal is selected using a 95 GHz local oscillator and a 93 GHz high-pass filter.

Calibration of electron cyclotron emission radiometer for KSTAR

We developed and installed an electron cyclotron emission radiometer for taking measurements of Korea Superconducting Tokamak Advanced Research (KSTAR) plasma. In order to precisely measure the absolute value of electron temperatures, a calibration measurement of the whole radiometer system was performed, which confirmed that the radiometer has an acceptably linear output signal for changes in input temperature. It was also found that the output power level predicted by a theoretical calculation agrees with that obtained by the calibration measurement. We also showed that the system displays acceptable noise-temperature performance around 0.23 eV.

Development of microwave imaging reflectometry in large helical device

Three key devices of the microwave imaging reflectometry (MIR) are under development in large helical device (LHD). The 2-D mixer array is developed by stacking the one-dimensional array of the planar Yagi-Uda antenna. The new type of the bandpass filter bank is modified to match the requirement of the MIR. The low-cost quadrature demodulator is also developed for the phase detection system. By using the low-price commercial wireless devices, the development cost becomes much lower than the expensive waveguide system. These devices enable the development of 2-D/3-D microwave imaging system for the plasma diagnostics and industrial applications.

High-resolution NMR spectra of n-alkanes penetrating into carbon fibers and of protons in carbon fibers

We present a simple NMR method for microscopically exploring the local environment in carbon fibers. The method utilizes n-alkanes as probe molecules, where the n-alkanes penetrate carbon fibers of interest. The high-resolution (1)H NMR spectra for a mixture of a carbon fiber and n-alkanes acquired by this method show a shift of the resonance line, which is due to the local structure of the fiber. The utility of this method is discussed on the basis of the (1)H NMR spectra obtained. In addition, the (1)H distribution and the local motion in the structure of the carbon fiber are revealed in view of the (1)H NMR spectra.

Dynamics of 9-hydroxyphenalenone studied by one-dimensional solid-state spin exchange NMR

We present a new NMR method to clarify the dynamics of proton tautomerism in solid 9-hydroxyphenalenone. Two 13C resonance lines influenced by the proton tautomerism have a chemical-shift difference between them, which increases with decreasing temperature. To depict the precise potential curve of the proton tautomerism, the chemical-shift difference when the proton tautomerism is completely frozen is necessary. For solid 9-hydroxyphenalenone and its derivatives, the freezing temperatures are often under -100 degrees C. When the freezing temperatures are below the temperature range in which standard magic angle spinning NMR probes can perform a sample spinning, it is very difficult to obtain the shift difference. The NMR experiments based on this new method are performed at a temperature significantly higher than -100 degrees C at which the proton tautomerism is still active. The new method yields the 13C spin relaxation rates, the rates for the proton tautomerism, and the populations of the two tautomers. Using the populations and the 13C chemical-shift difference at that temperature, we determined the chemical-shift difference at the freezing temperature. We also obtained several parameters characterizing the potential profile for the proton dynamics in solid 9-hydroxyphenalenone.

Sensitization of head and neck squamous cell carcinoma cells to Fas-mediated apoptosis by the inhibition of Bcl-X(L) expression

BACKGROUND

Various types of malignant tumor cells are known to acquire resistance to Fas receptor (Fas)-mediated apoptosis. In Fas-sensitive cells, Fas-mediated apoptosis is observed when anti-Fas antibody is bound to Fas. Bcl-2 and Bcl-X(L) are representative anti-apoptosis proteins reported to be capable of suppressing Fas-mediated apoptosis.

OBJECTIVE

To investigate the mechanism of resistance acquisition to Fas-mediated apoptosis in cultured human head and neck squamous cell carcinoma cells (HNSCCs).

METHODS AND RESULTS

We applied an anti-Fas antibody (CH11) to Fas-expressing HNSCCs (HSC-2) and the CH11 did not induce cell death in HSC-2. Treatment with actinomycin D (ActD) converted the phenotypes of HSC-2 from CH11-resistant to CH11-sensitive. Western blot analysis showed no differences between ActD-treated and ActD-untreated HSC-2 in the expression of Bcl-2. On the other hand, the expression of Bcl-X(L) was greatly reduced in ActD-treated HSC-2. Moreover, the reduction of Bcl-X(L) by specific antisense oligonucleotide treatment enhanced the CH11-induced cell death of HSC-2.

CONCLUSION

Our data suggest that Fas-signaling might be regulated by a Bcl-X(L)-inhibitable step in CH11-resistant HSC-2.

Inhibition of caspase-9 activity and Apaf-1 expression in cisplatin-resistant head and neck squamous cell carcinoma cells

We have previously reported that cisplatin induces caspase-9 (Casp9) activation in head and neck squamous cell carcinoma cells in vitro (HNSCCs). Our purpose here was to examine whether HNSCCs selected for resistance to cisplatin fail to exhibit Casp9 activation in response to cisplatin. The cisplatin-resistant HNSCCs (HSC-2CR) were selected from cisplatin-sensitive HNSCCs (HSC-2) for growth in the presence of cisplatin. Following cisplatin treatment, protelyzed Casp9 subunits were detected in HSC-2, but not detected in HSC-2CR. Using a direct enzymatic assay measuring cleavage of the synthetic peptide substrate (LEHD-AFC), Casp9 activity in cisplatin-treated HSC-2CR was less than that in cisplatin-treated HSC-2. Apoptotic protease-activating factor 1 (Apaf-1) has been shown to participate as an adaptor molecule in Casp9 activation. In the presence of cytochrome c (Cyt c) released from mitochondria, Apaf-1 binds to Casp9 and causes its activation. HSC-2 expressed 2-fold higher levels of Apaf-1 compared with HSC-2CR. On the other hand, following cisplatin treatment, the same degree of increase in cytoplasmic Cyt c was detected in both HSC-2 and HSC-2CR. These results suggest that in a certain type of HNSCCs, the inhibition of Casp9 activity and Apaf-1 expression may represent a mechanism of acquired cisplatin resistance.

[Inhibition of caspase-9 activity in cisplatin-resistant head and neck squamous cell carcinoma]

We have previously reported that cisplatin induces caspase-9 activation in head and neck squamous cell carcinoma cells (HNSCCs) in vitro, and the use of a specific inhibitor of caspase-9 blocks cisplatin-induced apoptosis in HNSCCs. Our purpose here was to determine whether HNSCCs selected for resistance to cisplatin fail to exhibit caspase-9 activation in response to cisplatin. Cisplatin-resistant HNSCCs (CRHNSCCs) were selected for growth in the presence of cisplatin. Following cisplatin treatment, no protelyzed caspase-9 subunits were detected in the CRHNSCCs, whereas proteolytic degradation of procaspase-9 was observed in parental cisplatin-sensitive HNSCCs (CSHNSCCs). Using a direct enzymatic assay measuring cleavage of the synthetic peptide substrate (LEHD-AFC), caspase-9 activity in cisplatin-treated CRHNSCCs was less than that in cisplatin-treated CSHNSCCs. Because caspase-9 activation requires the release of mitochondorial cytochrome c (Cyt c) into the cytoplasm, we determined the level of cytoplasmic Cyt c in response to cisplatin treatment. Interestingly, following cisplatin treatment, the same extent of increase in cytoplasmic Cyt c was evident and the expression of Bcl-2 family proteins (Bcl-2 and Bcl-XL) remained unchanged in both CRHNSCCs and CSHNSCCs. These results suggest that in certain HNSCC cell types, inhibition of caspase-9 activity represents another mechanism of acquired cisplatin resistance. This inhibition mechanism may be independent of the release of Cyt c into the cytoplasm.

[Resistance to Fas-mediated apoptosis in human papillomavirus type 16-immortalized human laryngeal epithelial cells after tumorigenesis]

Apoptosis plays an important role in such biological processes as multistep carcinogenesis. Human papillomavirus type 16(HPV16)-immortalized human epithelial cell lines are, for the most part, nontumorigenic in nude mice and useful for studying mechanisms involved in multistep carcinogenesis. We previously reported that HPV16-immortalized human laryngeal epithelial cell line HLEC16 formed tumors after treatment with 4-(methyl-nitrosamine)-1-(3-pyridyl)-1-butanone, and derived one tumorigenic cell line, HLEC16T. We compared sensitivity to Fas receptor-mediated apoptosis of nontumorigenic HLEC16 and tumorigenic HLEC16T. HLEC16 and HLEC16T expressed Fas protein (Fas) but not Fas-ligand (FasL) mRNA. We applied an anti-Fas monoclonal, antibody, CH11, to HLEC16 and HLEC16T, and monitored cell death. HLEC16T was found to be significantly less sensitive to CH11-mediated cell death that HLEC16. Western blot analysis showed no significant difference in levels of apoptosis-inducing protein, Bax, between HLEC16 and HLEC16T. Levels of apoptosis-inhibiting proteins Bcl-2 and Bcl-XL increased in HLEC16T. These results suggest that the inhibition of Fas-mediated apoptosis through apoptosis-inhibiting protein overexpression may promote tumorigenicity in HLEC16T.

[Resistance to Fas-mediated apoptosis in head and neck squamous cell carcinoma cells]

Various types of carcinoma cells have been shown to escape immune recognition by constitutive resistance to Fas receptor (Fas)-mediated apoptosis. The purpose of this study was to examine the sensitivity to Fas-mediated apoptosis of human head and neck squamous cell carcinoma (HNSCC) cells. We applied an anti-Fas monoclonal antibody (CH11) to HNSCC cell lines and monitored their cell death. All three HNSCC cell lines examined expressed Fas protein but not Fas-ligand mRNA. CH11 did not induce cell death (CH11-resistant) in any of the three HNSCC cell lines examined. Treatment with actinomycin D (ActD) converted the phenotypes of the CH11-resistant HNSCC cell lines from CH11-resistant to CH11-sensitive, suggesting that the resistance to CH11-induced apoptosis was dependent on RNA synthesis. Western blot analysis did not show any differences in expression of Bcl-2 between the non-treated and ActD-treated HNSCC cell lines. Expression of Bcl-XL, on the other hand, was greatly reduced in the ActD-treated HNSCC cell lines, implying that Fas signaling in the CH11-resistant HNSCC cell lines might be regulated by an Bcl-XL-inhibitable step.

Caspase-9 regulates cisplatin-induced apoptosis in human head and neck squamous cell carcinoma cells

The aim of this study was to understand the molecular requirements for cisplatin-induced apoptosis in human head and neck squamous cell carcinoma (HNSCC) cell death. Cisplatin induced apoptosis in HNSCC cell lines, HSC-2, HSC-3 and HSC-4 in a dose-dependent manner. However, cisplatin did not induce the expression of Fas-ligand mRNA or upregulation of Fas protein. By caspase activation assays, cisplatin induced Caspase-3 (Casp-3), -8 and -9 activation. In all three lines tested, the use of a specific inhibitor of Casp-9 almost completely blocked cisplatin-induced apoptosis, while the use of Casp-3 and -8 inhibitors resulted in a partial blockade of cisplatin-induced apoptosis. Our results strongly suggest that Casp-9-dependent apoptosis plays an important role in cisplatin-induced HNSCC apoptosis.