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Biomedical subjects

P H Chou

Publications and source records attributed to P H Chou.

14 recordsLinked to original sources
PubMed2006

Detection and identification of dyes showing AhR-binding affinity in treated sewage effluents.

A bioassay using the YCM3 recombinant yeast strain was utilised to investigate the presence of dioxin-like compounds that activate the aryl hydrocarbon receptor (AhR) in treated sewage effluents. AhR ligand activity was detected in the concentrated extracts of effluent samples collected in March, June and October 2004 from Kyoto city, Japan. HPLC fractionation was carried out using C18 reversed-phase columns, and possible AhR ligands were further isolated and purified. By using LC/MS/MS, one weak AhR ligand was identified to be rhodamine B base, a fluoran dye. In addition, two other coloured ligands were postulated to be disperse anthraquinone dyes or their metabolites because of their UV spectra and HPLC retention times. The AhR-binding affinities of 12 commercial dyes with different chemical structures were also studied. Among the dyes tested, hydrophobic anthraquinone dyes exhibited higher AhR ligand activity, but azo dyes or hydrophilic acid dyes showed no or very low AhR ligand activity. Rhodamine B base and disperse anthraquinone dyes were suggested to be potential xenobiotic AhR ligands. Future research regarding their contamination in aquatic environments and toxicological information is necessary.

Biological Assay↗
PubMed2002

Elbow load with various forearm positions during one-handed pushup exercise.

This is the first study of the one-handed pushup, and tries to show the effects of forearm rotations. Previous studies of elbow loading have focused on passive loading and small loads, because data from large loads during active exercise is not easy to obtain. In order to investigate the biomechanical impact of hand position on the elbow and the potential trauma mechanisms of outstretched elbow, joint loading across the elbow was analyzed for three forearm rotational positions, neutral, 90 degrees internal rotation and 90 degrees external rotation. Both kinematic and kinetic data were collected from eight volunteers by the Motion Analysis System and a Kistler Force Plate. Statistical analysis of the data delineates the relationship between elbow joint load and hand rotational position during one-handed pushup, and also provides useful biomechanical information for this challenging exercise. The axial and valgus stresses and forces are the major concerns. The peak axial forces exerted on the elbow joint averaged 65 % of the body weight when the hand position was neutral, and was significantly reduced with the hand rotated either internally or externally. The peak valgus shear force with the hand externally rotated was 50 % greater than the other two positions. Thus, outward rotation of the hand is a stressful position that should be avoided during one-handed pushup exercise or forward falls with outstretched hands in order to reduce the risk of elbow injuries.

Adolescent↗
PubMed2001

Sit-to-stand at different periods of pregnancy.

OBJECTIVE: This study was performed to determine the biomechanics of chair rising by pregnant women. DESIGN: Relative body joint position and ground reaction forces were measured by a motion analysis system and one force plate. BACKGROUND: Physiological and psychological changes during pregnancy impose postural demands and limit the performance of daily living activities such as rising from sitting to standing position. METHODS: Twenty-four pregnant women, divided into three groups, were studied performing sit-to-stand transition from an armless and adjustable chair. By kinematic and kinetic analysis, the angles and moments of hip, knee and ankle joints were investigated. RESULTS: The chair height has great influence on knee joint and hip joint moments, but less on ankle joints. In the third trimester for all chair heights, because of a marked increase in abdominal depth, the maximum hip moment is significantly less than that in first trimester, while the maximum knee moment is significantly larger. Pregnant women in third trimester produced larger knee moment during sit-to-stand transition from lower chair height. CONCLUSIONS: The mechanism of sit-to-stand is affected by the physical changes of pregnant women at different periods of pregnancy, e.g. increased loading of knee joint and decreased hip joint moment, especially in the last trimester period of pregnancy.

Adult↗
PubMed2001

Elbow load during pushup at various forearm rotations.

OBJECTIVE: Elbow joint loading was evaluated during pushup exercises at various forearm rotations. DESIGN: Subjects were asked to perform pushup in various forearm rotations: neutral, 90 degrees internal rotation, and 90 degrees external rotation. BACKGROUND: Training with pushup exercise is good for the muscles and joints of the upper extremities. However, excessive shear forces on the elbow might lead to injuries to either normal trainees or to handicapped people, especially for those who rely on elbow prosthesis. METHODS: The kinematics and kinetics of the elbow joint were investigated under various forearm rotations. RESULTS: The loading biomechanics of the elbow joint differed with various forearm rotations. It was noted that greater posterior and varus forces of the elbow are encountered with internal rotation of the hand position and, consequently, full forearm pronation. CONCLUSIONS: Pushup with hands in internally rotated position should be prevented so as to avoid excessive shear forces or moments. RELEVANCE: Knowledge of elbow kinematics and kinetics may be helpful in preventing injuries by reducing the elbow shear force with changes of forearm rotation.

Adult↗
PubMed2001

Effect of elbow flexion on upper extremity impact forces during a fall.

OBJECTIVE: The overall objectives are to develop a biomechanical model for a simulated fall with outstretched hand. DESIGN: Cross-sectional study involving young healthy volunteers in a university research laboratory setting. BACKGROUND: Little is known about the factors which influence fracture risk during a fall on outstretched hand. METHODS: A group of 11 male subjects volunteered for this investigation. A set of eight reflective markers was placed bilaterally on selected anatomic landmarks. Subjects were suspended with both elbows extended and wrists dorsiflexed, preparing to impact the ground and force plates from two different fall heights: 3 and 6 cm. Two different postures for the elbows were employed. In the elbow extension experiment, the elbows were extended at all times. In the elbow flexion experiment, the elbows were extended at impact, but then flexed immediately, as though in the initial downward phase of a push-up exercise. RESULT: Increasing the fall height significantly increased the upper extremity axial forces by 10% and 5%. No significantly different differences were found in the axial forces applied to the wrist, elbow or shoulder between the elbow flexion and elbow extension trials, but the elbow mediolateral shear force was 68% larger (P=0.002) in the extension trials. CONCLUSIONS: Performing an elbow flexion movement at impact reduces the first peak impact force value and postpones the maximum peak value. Although changing the fall arrest strategy from elbow extension to elbow flexion did not affect the peak impact force on the hand, it did require substantially greater elbow and shoulder muscle strengths. RELEVANCE: This paper yields insights into how the physical demands of arresting mild falls may relate to upper extremity muscle capacity, joint dislocation and bony fracture.

Accidental Falls↗
PubMed2001

Primary hyperparathyroidism and acute pancreatitis during the third trimester of pregnancy.

The simultaneous occurrence of maternal primary hyperparathyroidism (PHPT) and acute pancreatitis during pregnancy is very rare. We report a case of concurrent PHPT and pancreatitis during the third trimester of pregnancy. A summary of the relevant literature regarding the clinical course and recommended management in relation to this case is also presented.

Acute Disease↗
PubMed2000

Greater tuberosity osteotomy for treatment of impinge rotator cuff tear.

Forty-two consecutive patients in whom an impingement of rotator cuff tear had been treated with greater tuberosity osteotomy and repair were evaluated by relief of pain, return of range of motion and strength of shoulder. The oriental acromion is thin and easy to break during the traditional acromioplasty procedures. When the decompression is achieved by osteotomy on the greater tuberosity which is the common location of cuff tear, not only is adequate decompression achieved but also the coracoacromial ligament is preserved. Comparison of the results of greater tuberosity osteotomy with those of previous acromioplasty studies shows they are mostly similar. At present, these techniques can be recommended for use by Chinese orthopaedic surgeons who have to deal with the typical oriental bony structures.

Adult↗
PubMed1996

Mechanical property analysis of small bone fixators.

The purpose of this study is to establish a database and to compare mechanical properties between various types of small bone fixators. Hollow maple dowels are uniformly produced to simulate small bones in this study. Furthermore, transverse osteotomy, transverse osteotomy with 2 mm gap, and 45 degrees oblique osteotomies are created to simulate stable, unstable, and spiral fractures. Each fracture pattern is then approximated with four types of fixators: (1) Aesculap mini external fixator, (2) mini A-O plate and screw, (3) cross pin, and (4) self-assembled mini external fixator. Finally, tension, torsion, and bending tests are performed with INSTRON. In three different fracture patterns, dorsal plating has the strongest tensile rigidity and lateral bending rigidity. In stable and unstable fractures, Aesculap mini external fixator has the strongest torsional rigidity. However, mini A-O plate has the strongest torsional rigidity in 45 degrees oblique fractures. In stable fractures, dorsal plating, lateral plating, and mini external fixator all have good anterior bending rigidity without significant differences. Nevertheless, only lateral plating and mini external fixator show good anterior bending rigidity in unstable and 45 degrees oblique fractures. Except in torsional rigidity, Aesculap mini external fixator is not significantly stiffer than the self-assembled external fixator. As expected, cross pin is the weakest fixator. Differences in mechanical stiffiness between the four types of small bone fixators are provided in this study. Additionally, one should also consider the indication when choosing a proper fixator. Complication rate can then be lowered to achieve successful surgery in treating small bone fractures.

Bone Substitutes↗
PubMed1994

A fixational method of tendon transfer in foot surgery.

Tendon transfer has been used for correcting foot deformities and improving foot function in paralytic and spastic foot problems. The traditional fixational method by Cole's pull-out button often induces pressure sores which make the button sink and loosens the transferred tendon, leading to poor surgical results. By using a metal eye cover and pull-out wire instead of button and suture material, the transferred tendon can be firmly fixed. Moreover, the concavity of the metal eye cover is suitable for the arch of the foot that provides a large contact surface & even pressure distribution to prevent the most common complications of the pull-out button method, the pressure sore.

Female↗
PubMed1979

The role of central 5-hydroxytryptamine in acupuncture analgesia.

The role played by central 5-hydroxytryptamine (5-HT) in acupuncture analgesia (AA) has been studied in rats with the tail-flick response as the antinociceptive test. The analgesic effect of acupuncture can be enhanced or lowered by the increment or the decrement of the 5-HT level in the CNS. Furthermore, the turnover rate of 5-HT in the CNS has been found to be greatly facilitated during the period of acupuncture. The results imply that 5-HT in the CNS may be one of the most important neurochemical agents mediating AA.

5,6-Dihydroxytryptamine↗