Erratum: Correction of Tables in the Article "Reference Respiratory Muscle Strength Values and a Prediction Equation Using Physical Functions for Pulmonary Rehabilitation in Korea".

This corrects the article on p. e325 in vol. 38, PMID: 37846788.

Differences in muscle activity during squat exercises according to the knee angle and standing angle of a sliding tilt table: A comparative study.

BACKGROUND AND PURPOSE: Weight-bearing exercises can help improve physical function; however, they may be difficult to perform in patients with neurological issues or lower limb fractures. The purpose of this study was to evaluate the activity of the leg muscles during squatting when using a new exercise aid designed to help patients with difficulty in performing squats, termed the sliding tilt table, at different knee angles and to estimate the squat level for each angle. METHODS: This study was a cross-sectional, observational study performed in the general community. Participants comprised 30 healthy adult men. Squats were performed by setting the knee joints at 30, 60, and 90° and the tilt table angles to 15, 30, and 45°. The muscle activity of the vastus medialis, tibialis anterior, and gastrocnemius was measured using surface electromyography. RESULTS: As the tilt table and knee joint angle increased, the %maximal voluntary isometric contraction increased. Similar patterns were found in both legs. CONCLUSIONS: Weight-bearing exercises, such as squats, are important exercise elements in patients who require lower limb rehabilitation. Therefore, it is necessary to provide efficient lower limb rehabilitation exercises by adjusting the squat level according to the patient's ability, which can be achieved using a sliding tilt table.

Reference Respiratory Muscle Strength Values and a Prediction Equation Using Physical Functions for Pulmonary Rehabilitation in Korea.

BACKGROUND: In Korea, tests for evaluating respiratory muscle strength are based on other countries' clinical experience or standards, which can lead to subjective evaluations. When evaluating respiratory function based on the standards of other countries, several variables, such as the race and cultures of different countries, make it difficult to apply these standards. The purpose of this study was to propose objective respiratory muscle strength standards and predicted values for healthy Korean adults based on age, height, weight, and muscle strength, by measuring maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and peak cough flow (PCF). METHODS: This cross-sectional study analyzed MIP, MEP, and PCF in 360 people, each group comprising 30 adult men and women aged 20-70, diagnosed as healthy after undergoing medical check-ups at a general hospital. Hand grip strength (HGS) and the five times sit-to-stand test (FTSST) results were also recorded. Correlations among respiratory muscle strength, participant demographics, and overall muscle strength were evaluated using Pearson's correlation analysis. The predicted values of respiratory muscle strength were calculated using multiple regression analysis. RESULTS: Respiratory muscle strength differed from the values reported in studies from other countries. In the entire samples, both MIP and MEP had the highest correlations with peak HGS (r = 0.643, r = 0.693; P < 0.05), while PCF had the highest correlation with forced expiratory volume in 1 s (r = 0.753; P < 0.05). Age, body mass index, peak HGS, and FTSST results were independent variables affecting respiratory muscle strength. A predictive equation for respiratory muscle strength was developed using the multiple regression equation developed in this study. CONCLUSION: Respiratory muscle strength index may differ by country. For more accurate diagnoses, standard values for each country are required. This study presents reference values for Korea, and a formula for estimation is proposed when no respiratory muscle strength measurement equipment is available. TRIAL REGISTRATION: Clinical Research Information Service Identifier: KCT0006778.

Sustained release docetaxel-incorporated lipid nanoparticles with improved pharmacokinetics for oral and parenteral administration.

The aim of this study was to develop docetaxel-incorporated lipid nanoparticles (DTX-NPs) to improve the pharmacokinetic behaviour of docetaxel (DTX) after oral and parenteral administration via sustained release. DTX-NPs were prepared by nanotemplate engineering technique with palmityl alcohol as a solid lipid and Tween-40/Span-40/Myrj S40 as a surfactants mixture. Spherical DTX-NPs below 100 nm were successfully prepared with a narrow particle size distribution, 96% of incorporation efficiency and 686 times increase in DTX solubility. DTX-NPs showed a sustained release over 24 h in phosphate-buffered saline and simulated gastric and intestinal fluids, while DTX-micelles released DTX completely within 12 h. The half-maximal inhibitory concentration (IC50) of DTX-NPs against human breast cancer MCF-7 cells was 1.9 times lower than that of DTX-micelles and DTX solution. DTX-NPs demonstrated 3.7- and 2.8-fold increase in the area under the plasma concentration-time curve compared with DTX-micelles after oral and parenteral administration, respectively.

High payload itraconazole-incorporated lipid nanoparticles with modulated release property for oral and parenteral administration.

OBJECTIVES: The aim of this study was to develop high payload itraconazole-incorporated lipid nanoparticles (HINP) with modulated release property using a binary mixture core of solid and liquid lipid for oral and parenteral administration. METHODS: High payload itraconazole-incorporated lipid nanoparticles were prepared by hot high-pressure homogenization method using tristearin (TS) as a solid lipid, triolein (TO) as a liquid lipid and egg phosphatidylcholine/Tween 80/DSPE-PEG2000 as a surfactants mixture. To investigate the effects of liquid lipid in lipid core on itraconazole (ITZ) dissolution and release, TS/TO ratio was varied as 100/0, 90/10 and 80/20 (mg/mg). KEY FINDINGS: All HINP formulations showed particle size around 300 nm and polydispersity index below 0.3. The incorporation efficiencies of HINP formulations were above 80%, and more than 40 mg of ITZ was incorporated into each HINP formulation. In-vitro dissolution and release rate of ITZ from HINP increased as the amount of TO in lipid core increased. Compared with commercial formulations of ITZ, the pharmacokinetics of ITZ was improved after oral and parenteral administration of HINP formulations containing 0% or 10% of TO in lipid core. CONCLUSION: High payload itraconazole-incorporated lipid nanoparticles with a binary mixture lipid core have a great potential for the development of controlled release formulation of ITZ.

Enhanced anti-rheumatic activity of methotrexate-entrapped ultradeformable liposomal gel in adjuvant-induced arthritis rat model.

The aim of this study is to investigate in vivo anti-rheumatic activity of methotrexate-entrapped ultradeformable liposomal gel (MTX-UDLs-gel) in adjuvant-induced arthritis rat model. Methotrexate-entrapped ultradeformable liposomes (MTX-UDLs) with the optimal phosphatidylcholine to Tween 80 ratio (7:3, w/w) were incorporated into 1% Carbopol gel. MTX-UDLs-gel was characterized in terms of appearance, clarity, homogeneity, pH and drug content. The permeation of MTX-UDLs-gel across rat skin was investigated using Franz diffusion cell. In vivo anti-rheumatic activity of MTX-UDLs-gel was assessed in terms of edema volume, paw edema and leukocyte infiltration scores, histopathological analysis and inflammatory cytokines level in complete Freund's adjuvant (CFA)-induced arthritis rat model. MTX-UDLs-gel showed good homogeneity and clarity, neutral pH and about 99.5% drug content. The cumulative amount of MTX permeated for 24h from MTX-UDLs-gel (164.6µg) was 1.5 and 2.15 times higher than that of MTX-CLs-gel (113.3µg) and MTX-plain-gel (76.6µg), respectively. MTX-UDLs-gel significantly alleviated the severity of inflammation by reducing edema volume, histological scores and accumulation of neutrophils and improving tissue architecture in CFA-induced arthritis rat model. MTX-UDLs-gel effectively suppressed the expression of pro-inflammatory cytokines, TNF-α and IL-1ß, in paw tissues. In conclusion, the developed MTX-UDLs-gel has a great potential for effective delivery of MTX into the inflamed joints in rheumatoid arthritis.

The effect of the shoulder stability exercise using resistant vibration stimulus on forward head posture and muscle activity.

[Purpose] The purpose of this study was to analyze shoulder stabilization using resistant vibration stimulus during bodyblade exercise followed by forward head posture improvement. [Subjects and Methods] Craniovertebral angle and cranial rotation angle were measured with 24 patients who were diagnosed with forward head posture. The experimental group conducted bodyblade exercise for 6 weeks and all patients received conventional physical therapy. The craniovertebral angle and cranial rotation angle were measured using a diagnostic imaging device to measure the change in forward head posture. Sternocleidomastoid, upper trapezius and serratus anterior muscle activity were measured using surface electromyography, voluntary contraction was converting into a percentage and mean value was calculated. [Results] The experimental group showed a significant increase in the comparison of the results of both groups before and after the intervention. The comparing group showed no significant difference. The experimental group showed the significant difference in mean value after the intervention in the comparison between the groups. [Conclusion] Resistant vibration stimulus by bodyblade controlled shoulder muscle activity causing scapular stabilization followed by neck position stability improvement. Rehabilitation program that activates whole kinetic chain of proximal and distal muscles such as bodyblade will show more effective improvement when choosing rehabilitation program for neck and shoulder disease clinically.

Enhanced acute anti-inflammatory effects of CORM-2-loaded nanoparticles via sustained carbon monoxide delivery.

The aim of this study was to enhance the anti-inflammatory effects of carbon monoxide (CO) via sustained release of CO from carbon monoxide-releasing molecule-2-loaded lipid nanoparticles (CORM-2-NPs). CORM-2-NPs were prepared by hot high pressure homogenization method using trilaurin as a solid lipid core and Tween 20/Span 20/Myrj S40 as surfactant mixture. The physicochemical properties of CORM-2-NPs were characterized and CO release from CORM-2-NPs was assessed by myoglobin assay. In vitro anti-inflammatory effects were evaluated by nitric oxide assay in lipopolysaccharide-stimulated RAW 264.7 macrophages. In vivo anti-inflammatory activity was investigated by measuring paw volumes and histological examination in carrageenan-induced rat paw edema. Spherical CORM-2-NPs were around 100nm with narrow particle size distribution. The sustained CO release from CORM-2-NPs was observed and the half-life of CO release increased up to 10 times compared with CORM-2 solution. CORM-2-NPs showed enhanced in vitro anti-inflammatory effects by inhibition of nitric oxide production. Edema volume in rat paw was significantly reduced after treatment with CORM-2-NPs. Taken together, CORM-2-NPs have a great potential for CO therapeutics against inflammation via sustained release of CO.

Analysis of electromyographic activities of the lumbar erector spinae caused by inversion traction.

[Purpose] The purpose of this study was to analyze changes in the electromyographic activities of the lumbar erector spinae caused by inversion traction in order to verify the relaxation effect. [Subjects and Methods] The subjects included 60 healthy male adults who were equally and randomly assigned to a 30-30° group, a 30-60° group, and a 60-60° group. Inversion traction was performed for six minutes, and the electromyographic activities of the lumbar erector spinae (L2, L4) were measured before and after inversion traction. [Results] The root mean square values at the L2 and L4 levels on both sides were statistically significantly higher after inversion traction compared with before inversion traction. Before inversion traction, the root mean square values at the L2 and L4 levels on both sides in the 30-60° group and 60-60° group were significantly higher than those in the 30-30° group, while the root mean square values at the L2 and L4 levels on both sides showed no significant differences between the groups before inversion traction. [Conclusion] The findings of this study indicated that IT is more likely to elicits an increase in muscle tension and prevent relaxation of the lumbar erector spinae.

Comparison of dynamic balance ability in healthy university students according to foot shape.

[Purpose] This study aimed to compare dynamic balance ability according to foot shape, defined as normal, pronated, or supinated on the basis of the height of the medial arch. [Subjects] In this study, 14 subjects for the pronated foot group, 14 for the supinated foot group, and 14 for the normal foot group were selected from among 162 healthy university students by using the navicular drop test proposed by Brody. To measure dynamic balance ability, a star excursion balance test (SEBT) was conducted for each group, in which a cross-shaped line and lines at 45° in eight directions were drawn on the floor. In this study, only three directions were used, namely anterior, posterolateral, and posteromedial. The mean of the SEBT was calculated by measuring three times for each group, and the values were standardized using the following equation: measured value/leg length × 100. [Results] No significant differences in dynamic balance ability were found between the normal, pronated, and supinated foot groups. [Conclusion] No significant differences in dynamic balance ability according to the foot shape were found among the healthy university students with normal, pronated, and supinated feet.

Effect of topographical control by a micro-molding process on the activity of human Mesenchymal Stem Cells on alumina ceramics.

BACKGROUND: Numerous studies have reported that microgrooves on metal and polymer materials can affect cell adhesion, proliferation, differentiation and guidance. However, our knowledge of the cell activity associated with microgrooves on ceramics, such as alumina, zirconia, hydroxyapatite and etc, is very incomplete, owing to difficulties in the engraving of microgrooves on the hard surface of the base material. In this study, microgrooves on alumina were fabricated by a casting process using a polydimethylsiloxane micro-mold. The cell responses of Human Mesenchymal Stem Cells on the alumina microgrooves were then evaluated. RESULTS: Microgrooves on an alumina surface by micro-mold casting can enhance the adhesion, differentiation of osteoblasts as well as gene expression related to osteoblast differentiation. The ALP activity and calcium concentration of the cells on alumina microgrooves were increased by more than twice compared to a non-microgrooved alumina surface. Moreover, regarding the osteoblast differentiation of hMSCs, the expression of ALP, RUNX2, OSX, OC and OPN on the microgrooved alumina were all significantly increased by 1.5 ~ 2.5 fold compared with the non-microgrooved alumina. CONCLUSION: Altering the topography on alumina by creating microgrooves using a micro-molding process has an important impact on the behavior of hMSCs, including the adhesion, differentiation of osteoblasts and osteoblast-specific gene expression. The significant increase in hMSC activity is explained by the increasing of material transportation in parallel direction and by the extending of spreading distance in perpendicular direction.

Changes in cervical muscle activity according to the traction force of an air-inflatable neck traction device.

[Purpose] The purpose of this study was to analyze cervical muscle activity at different traction forces of an air-inflatable neck traction device. [Subjects] Eighteen males participated in this study. [Methods] The subjects put on an air-inflatable neck traction device and the traction forces administered were 40, 80, and 120 mmHg. The electromyography (EMG) signals of the splenius capitis, and upper trapezius were measured to assess the muscle activity. [Results] The muscle activity of the splenius capitis was significantly higher at 80, and 120 mmHg compared to 40 mmHg. The muscle activity of the upper trapezius did not show significant differences among the traction forces. [Conclusion] Our research result showed that the air-inflatable home neck traction device did not meet the condition of muscle relaxation.

Surface functionalization of microgrooved titanium with dual growth factor-releasing nanoparticles for synergistic osteogenic differentiation of human mesenchymal stem cells.

We demonstrate that dual release of bone morphogenic protein-2 (BMP-2) and insulin-like growth factor-1 (IGF-1) by catechol-functionalized adhesive polymer nanoparticles on microgrooved titanium (Ti) surface enhances in vitro osteoblastic differentiation of human mesenchymal stem cells (MSCs). The nanoparticles consisted of three distinct domains, surface Ti-adhesive catechol groups, anionic poly(L-aspartic acid) (PAsp) shells, and hydrophobic poly(L-phenylalanine) (PPhe) cores. The immobilization of the adhesive nanoparticles onto microgrooved Ti surface was verified using various surface analytical tools, such as field-emission scanning electron microscopy (Fe-SEM), X-ray photoelectron spectroscopy (XPS), contact angle measurement. The nanoparticles were immobilized both on the groove bottom surface and the ridge top surface with a similar anchoring density. A fluorescence microscope visualized that BMP-2 and IGF-1 of positive charges were efficiently loaded onto the negatively charged PAsp shells of immobilized nanoparticles. We confirmed the enhanced osteoblastic differentiation of MSCs by presenting the expression results of major osteoblast marker genes and proteins. In addition, overall significant correlations between the experimental results verified the validity of our study. The proposed combined surface of microgrooves and growth factor-releasing nanoparticles can be used as a strong osteogenic promoter on various biomaterial surfaces.

Comparison of skin sensory thresholds using pre-programmed or single-frequency transcutaneous electrical nerve stimulation.

[Purpose] The purpose of the present study was to compare the sensory thresholds of healthy subjects using pre-programmed or single-frequency transcutaneous electrical nerve stimulation. [Subjects] Ninety healthy adult subjects were randomly assigned to pre-programmed or single-frequency stimulation groups, each consisting of 45 participants. [Methods] Sensory thresholds were measured in the participants' forearms using von Frey filaments before and after pre-programmed or single-frequency transcutaneous electrical nerve stimulation, and the result in values were analyzed. [Results] Significant increases in sensory threshold after stimulation were observed in both groups. However, there were no significant differences between the two groups in sensory thresholds after stimulation or in the magnitude of threshold increases following stimulation. [Conclusion] Our results show that there are no differences between sensory threshold increases induced by pre-programmed and single-frequency transcutaneous electrical nerve stimulation.

Effect of Treatment Table Height on Shoulder Muscles during Ultrasound Therapy Work.

[Purpose] The purpose of this study was to propose a table height that can reduce shoulder muscle fatigue by analyzing and comparing median frequencies of shoulder muscles at different table heights when performing therapeutic ultrasounds work. [Subjects and Methods] The subjects were 63 healthy male adults who were equally and randomly assigned to a standard height group (SHG), a high height group (HHG), and a low height group (LHG). The standard table height was set at the level of the elbow joint when the subjects flexed their elbow while in a sitting position. High height and low height were set 10 cm higher and 10 cm lower, respectively, than the standard height. Muscle fatigue of the upper trapezius, middle deltoid, rhomboid, and infraspinatus of the subjects was measured during ultrasound treatment work at each table height. [Results] Median frequencies of the upper trapezius, middle deltoid, rhomboid, and infraspinatus muscles were significantly lower in the HHG than in to the LHG. [Conclusion] When therapeutic ultrasound is performed using a table that has a height lower than that of the elbow joint, the median frequency of the shoulder muscle increases, hence decreasing muscle fatigue. This way, musculoskeletal pain as a result of performing therapeutic ultrasound can be prevented.

The influence of neuromuscular electrical stimulation on the heart rate variability in healthy subjects.

[Purpose] The purpose of this study was to examine the effect of neuromuscular electrical stimulation (NMES) on heart rate variability (HRV). [Subjects and Methods] Ten healthy subjects participated in the study. All subjects received NMES with a pulse duration of 300 us and frequency of 30 Hz at the vastus lateralis and vastus medialis for 15 minutes. The stimulation intensity was adjusted in the range of 20 to 30 mA. HRV using a pulse oximeter was measured in the sitting position before and after NMES. [Results] After the NMES, all HRV data slightly increased, but there was no significance between before and after data. [Conclusion] We suggest that strengthening exercises using NMES may be undertaken safely.

Thermal stability of gallium-doped zinc oxide thin film on glass substrates by an RF sputtering process.

The effects of a heat treatment on the structural and electrical properties of GZO thin films grown by RF magnetron sputtering were investigated. The heat treatment involved temperatures in the range from 200 degrees C to 500 degrees C under air. As the temperature was increased, the electrical properties of GZO thin films increased exponentially and the surface morphology was drastically altered. The effect of temperature is discussed based on electrical and structural characterization of the materials.

Analysis of muscle fatigue of erect spinae caused by treatment table height in ultrasound therapy.

[Purpose] The objective of this study was to propose a work environment that could reduce musculoskeletal workload. Accordingly, spinal muscle fatigue caused by ultrasound therapy at various treatment table heights was examined and compared. [Subjects and Methods] Twenty-five healthy subjects participated in this experiment. The table height was set to 100%, 125%, and 150% of the stool height (45 cm). The electromyographic signals of the erector spinae at the thoracic (T10, T12) and lumbar (L2, L4) levels were collected by an electromyography (EMG) system during the performance of ultrasound therapy. The median frequencies were then calculated and compared. [Results] The lower the table height was, the smaller the median frequencies of thoracic and lumbar erector spinae on both sides were. The T10 and T12 levels on both sides and the left L2 region showed significant differences among the table heights. At every spinal level, the median frequency of the left erector spinae was lower than that of the right: T10, T12, L2, and L4 at 100%, L4 at 125%, and T10, T12, L2, and L4 at 150% showed significant differences. [Conclusion] During ultrasound therapy muscle fatigue increased at higher table heights and the muscle fatigue of the left erector spinae was greater than that of the right side. To reduce muscle fatigue, we recommend the table height work is raised to an appropriate height, and that is shared between left and right arms.

Activities of the Vastus Lateralis and Vastus Medialis Oblique Muscles during Squats on Different Surfaces.

[Purpose] The purpose of the present study was to examine the effects of squat exercises performed on different surfaces on the activity of the quadriceps femoris muscle in order to provide information on support surfaces for effective squat exercises. [Subjects and Method] Fourteen healthy subjects performed squat exercises for five seconds each on three different support surfaces: hard plates, foam, and rubber air discs. Their performance was measured using electromyography. As the subjects performed the squat exercises on each surface, data on the activity of the vastus medialis oblique and the vastus lateralis, and the vastus medials oblique/vastus lateralis ratio, were collected. [Results] The activity of the vastus medialis oblique and the vastus medialis oblique/vastus lateralis ratio were found to be statistically significantly higher on rubber air discs than when the squats were performed on hard plates or foam. [Conclusion] To activate the vastus medialis obilique, and to enhance the vastus medialis oblique/vastus lateralis ratio, unstable surfaces that are highly unstable should be selected.