Biomedical subjects

Y L Chou

Publications and source records attributed to Y L Chou.

At least 19 recordsLinked to original sources

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

Incidence of transitional cell carcinoma and arsenic in drinking water: a follow-up study of 8,102 residents in an arseniasis-endemic area in northeastern Taiwan.

A significant association between ingested arsenic and bladder cancer has been reported in an arseniasis-endemic area in southwestern Taiwan, where many households share only a few wells in their villages. In another arseniasis-endemic area in northeastern Taiwan, each household has its own well for obtaining drinking water. In 1991-1994, the authors examined risk of transitional cell carcinoma (TCC) in relation to ingested arsenic in a cohort of 8,102 residents in northeastern Taiwan. Estimation of each study subject's individual exposure to inorganic arsenic was based on the arsenic concentration in his or her own well water, which was determined by hydride generation combined with atomic absorption spectrometry. Information on duration of consumption of the well water was obtained through standardized questionnaire interviews. The occurrence of urinary tract cancers was ascertained by follow-up interview and by data linkage with community hospital records, the national death certification profile, and the cancer registry profile. Cox proportional hazards regression analysis was used to estimate multivariate-adjusted relative risks and 95% confidence intervals. There was a significantly increased incidence of urinary cancers for the study cohort compared with the general population in Taiwan (standardized incidence ratio = 2.05; 95% confidence interval (CI): 1.22, 3.24). A significant dose-response relation between risk of cancers of the urinary organs, especially TCC, and indices of arsenic exposure was observed after adjustment for age, sex, and cigarette smoking. The multivariate-adjusted relative risks of developing TCC were 1.9, 8.2, and 15.3 for arsenic concentrations of 10.1-50.0, 50.1-100, and >100 microg/liter, respectively, compared with the referent level of < or =10.0 microg/liter.

Adult↗

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

The effect of changing the foot progression angle on the knee adduction moment in normal teenagers.

The effect of changing the foot progression angle on the peak knee adduction moment (KAM) during stance was investigated in 48 teenagers. They underwent gait analysis when walking in three different postures: normal walking, intentional in-toeing, and intentional out-toeing. The peak KAM when in-toeing was the highest and was statistically different from that seen in the normal walking or in the out-toeing posture. These findings may have clinical significance in adult life.

Adolescent↗

PubMed2001

Multiple actinomyces brain abscesses: case report.

A case of multiple cerebral abscesses caused by actinomyces is reported in a 37 year old male with mucoepidermoid carcinoma of the right lung. In conjunction with penicillin, sulfonamide and erythromycin, the patient underwent stereotactic surgery for aspiration of the brain abscesses under (CT). The bacteria, considered to originate from the right lung, were identified from the abscess material obtained at surgery. Using proper therapy to control infection and intracranial pressure is important. A lon g term follow up with frequent computerised tomography evaluation has been conducted and the patient outcome has been successful recovery.

Actinomycosis↗

PubMed2001

The effect of magnitudes and duration of pressure on cerebral cortex in a rat model.

The aim of this biomechanical study was to investigate the pressure-time-damage relationship on the cerebral cortex using a rat model. During brain surgery, additional cortical injuries induced by traction have been an important clinical issue. A total of 84 rats underwent a unilateral craniectomy, and conduction by hydrostatic pressure loading through a modified central venous pressure device with various combinations of magnitudes ranging from 0.5 to 10 cm H2O and duration from 0.5 to 20 minutes was then performed. Histopathological examination has exhibited three patterns of clustered, spotted damaged neurons and undamaged neuron. Two best-fitted exponential curves were derived from the data to establish the damaged, critical and tolerable loadings responsible for the neuron viability. This research provides information to enhance understanding of the additional cortex injuries induced by traction. Furthermore, the results may have implications in providing clinical guidance and/or development of alarm systems for minimising cortical damage during surgery.

Animals↗

PubMed2001

Potential of the genetic algorithm neural network in the assessment of gait patterns in ankle arthrodesis.

The aim of this study was to develop an empirical model of parameter-based gait data, based on an artificial neural network and a genetic algorithm, for the assessment of patients after ankle arthrodesis. Ground reaction force vectors were measured by force platforms during level walking. Nine force parameters expressed in percentage of body weight and their chronologic incidence of occurrence expressed in percentage of stance phase period were used in modeling. Ten healthy persons and ten patients who had solid arthrodesis of the ankle were recruited in this study for developing the model. By applying the genetic algorithm neural network, the percentage of correct classification was 98.8% and the subset of discriminant parameters was be reduced to 9 out of 18. These key parameters were mainly related to the loading response and propulsive phase. This indicates that there was a reduction in the abilities in cushion impact and push off in the patients after ankle arthrodesis. Finally, the relative distance (Dr) was defined in this study and used in two new patients' examinations to demonstrate its clinical utility.

Adult↗

PubMed2000

Foot progression angle and ankle joint complex in preschool children.

OBJECTIVE: The influence of foot progression angle on the ankle joint and the effects on gait patterns and mechanisms in skeletally normal preschool children was investigated. DESIGN: Kinematics and kinetics of the ankle joint were analyzed for preschool children who were skeletally normal but walked with different foot progression angle. BACKGROUND: The most frequent reasons for preschool children to be brought to a paediatric orthopaedic clinic are toe-in and toe-out. Without understanding the biological and biomechanical implications, treatment for these problems can be very confusing. METHODS: Gait analysis was performed in 86 skeletally normal preschool children. Children were grouped according to their foot progression angles. Analysis of the kinematics and kinetics of the ankle joint was intended to elucidate the gait mechanism. RESULTS: Children with different foot progression angles had distinctive patterns of spatio-temporal parameters, ground reaction force, joint angle, moment, power, and mechanical work of the ankle joints. The differences were organized and explained as different walking patterns and tactics. CONCLUSIONS: Skeletally normal preschool children with excessive toe-in or toe-out foot progression angles are not necessarily in some diseased status. They were instead related to different walking patterns. Aggressive treatment for these problems is not recommended.RelevanceThese results suggest that toe-in and toe-out are related to walking speed which has distinct influences on the kinematics and kinetics of the ankle joint. Though the observed problems were seemingly only in the transverse plane, they are in fact three-dimensional and have a mutually close relationship. The findings could be linked to the promptness of muscle response and the habits of walking in preschool children. Better understanding of possible mechanisms will help parents and paediatricians decide on the most appropriate treatment for these children.

Ankle Joint↗

PubMed2000

Common abnormal kinetic patterns of the knee in gait in spastic diplegia of cerebral palsy.

We studied the kinetic characteristics of the knee in patients with spastic diplegia. Twenty three children with spastic diplegia were recruited and had their 46 limbs categorised into the following four groups: jump (n=7), crouch (n=8), recurvatum (n=14) and mild (n=17). In the crouch pattern, the patients usually had a larger and longer lasting internal knee extensor moments in stance suggesting that rectus femoris had a relatively high activation. In the recurvatum pattern, the internal knee flexor moment was large and long lasting in stance. The biceps femoris showed less activity on EMG although the knee flexor moment was large and we concluded that the soft tissue behind the knee joint provided this flexor moment. In the jump knee pattern there was abnormal power generation at the knee and ankle joints in initial stance, which did not contribute to normal progression but aided upward body motion. In the mild group the kinetic data was similar to that seen in normal children. Knowledge of kinetic patterns in these patients may help in their subsequent management.

Ankle Joint↗

PubMed2000

Gait analysis and energy consumption of below-knee amputees wearing three different prosthetic feet.

This study scientifically measures the dynamic gait characteristics and energy consumption of 16 male below-knee amputees, eight vascular and eight traumatic, while wearing solid ankle cushion heel (SACH), single axis and multiple axis prosthetic feet via six-camera motion analysis, metabolic measurement cart and heavy-duty treadmill. Subjective results are additionally determined via questionnaire after testing. Motion analysis showed statistically significant differences at P<0.05 between the SACH, single axis and multiple axis foot in the velocity, cadence, stride length and single limb stance. Significant differences were found in energy consumption between the traumatic and vascular groups, and significant changes in walking under different speeds and different inclines. Results provide quantitative and qualitative information about the dynamic performance of the various feet, which can be helpful in prescribing the optimal prosthetic foot for individual amputees.

Adult↗

PubMed2000

Gait analysis after ankle arthrodesis.

The purpose of this study was to employ a computerized motion analysis system to identify the effect of ankle arthrodesis on the three-dimensional kinematic behavior of the rear and fore foot during level walking. A three-segment rigid body model was used to describe the motion of the foot and ankle. The results demonstrated that sagittal plane motion of the hindfoot was significantly decreased in the foot of patients having had ankle arthrodesis compared to normal subjects. The kinematic data indicated a generalized stiffness of the hindfoot on the involved foot in the sagittal plane. Sagittal plane movement in the forefoot and transverse plane movements in the hindfoot and forefoot increased in patients compared to controls.

Adolescent↗

PubMed2000

Comparison of two-dimensional and three-dimensional techniques for determination of facial motion--absolute movement in a local face frame.

BACKGROUND AND PURPOSE: Few studies have used motion analysis in the study of facial animation. A facial animation model using an expert vision motion analysis system was developed in this study to quantitatively evaluate absolute movement during five facial animations. METHODS: Skin markers were adhered to the face of each subject at 16 anatomic landmarks selected to represent the functional movement of the facial muscles. Three of the 16 skin markers were used to establish a local face frame with the origin in the mid-point of the face. All of the coordinates measured in the laboratory frame were rotated and translated to the local face frame for analysis. The trajectory of the facial markers was evaluated from the local face frame when comparing two-dimensional (2-D) displacement of skin markers (frontal plane) with three-dimensional (3-D) values by paired Student's t-test. RESULTS: Although the correlation of 2-D and 3-D displacements of skin markers was high (r > 0.69), the differences between 2-D and 3-D motion were significant (p < 0.001). The 2-D displacement of skin markers underestimated the 3-D facial animation in each marker and animation. There were no significant differences in the movement of both mouth angles or of the eyes. Thirty repeated measurements of a subject revealed good concentration in 3-D displacement, velocity, and angle of movement in smiling. The measurement error was less than 0.06 mm. The normative displacement of individual anatomic landmarks was evaluated to avoid size differences of individual faces. CONCLUSIONS: We suggest that the expert vision motion analysis technique is feasible for quantitative evaluation of absolute facial movement and would be useful for further clinical evaluation of patients with facial palsy.

Adult↗

PubMed2000

Fatal and non-fatal chromobacterial septicemia: report of two cases.

Chromobacterium violaceum is frequently found in soil and water in tropical and subtropical regions. The organism rarely causes infection in humans, but is associated with a high mortality rate when it occurs. Septicemia associated with abscess in multiple organs such as the liver, skin, lungs, spleen, lymph nodes, and brain has been reported. We report on 2 patients with systemic infections with Chromobacterium violaceum. One presented with a fulminant course with multiple organ involvement and died 78 days later. The other presented with a milder course and survived after antibiotic therapy. In conclusion, infection with Chromobacterium violaceum is rare but its course is usually fulminant with high mortality especially in patients with sepsis and multiple organ involvement. We hope this report will provide additional information to physicians in the treatment of this disease.

Adult↗

PubMed1998

Evaluation of enzyme-linked immunosorbent assay for the determination of polycyclic aromatic hydrocarbons in house dust and residential soil.

Two commercially available enzyme-linked immunosorbent assays (ELISA) for total polycyclic aromatic hydrocarbon (PAH) and carcinogenic PAH (C-PAH) were evaluated. The testing procedures were refined for application to screening PAH and C-PAH in house dust and soil samples for human exposure studies. The overall method precision expressed as percent relative standard deviation (%RSD) of triplicate real world dust and soil samples was within +/- 29% (12-29%) for PAH ELISA and +/- 21% (5.9-21%) for C-PAH ELISA. Spike recoveries from real world dust/soil samples were 114 +/- 30% for phenanthrene from PAH ELISA and 120 +/- 8.2% for benzo[a]pyrene from C-PAH ELISA. The overall method accuracy for PAH and C-PAH assays cannot be assessed for multiple PAH components in dust/soil samples (which represent real-world samples), because of the assays' cross reactivities with other PAH components. Over 100 dust/soil samples from 13 North Carolina homes and 22 Arizona homes were analyzed by PAH and C-PAH assays, as well as by the conventional gas chromatography/mass spectrometry (GC/MS) method. Statistical analysis showed that dust/soil PAH data from ELISA and GC/MS methods are significantly different. In general PAH ELISA responses were higher than PAH GC/MS responses. The regression analysis showed that the linear relationship between ELISA and GC/MS measurements is not strong in the combined data. The relationship became stronger for the data from the same type of dust/soil samples. The screening performance of ELISA was evaluated based on the frequency distribution of ELISA and GC/MS data. The results indicated that the ELISA PAH and C-PAH assays cannot be used as a quantitative analytical tool for determining PAH in real-world dust/soil samples. However, the ELISA is an effective screening tool for ranking PAH concentrations in similar types of real world dust/soil samples.

Chromatography, Gas↗

PubMed1995

Strength of the pin-bone interface of external fixation pins in the iliac crest. A biomechanical study.

The iliac crest is a frequent insertion site for external fixation pins in treating unstable pelvic or acetabular fractures and in iliofemoral distraction for superiorly dislocated hips. The pin-bone interface is critical for the success of treatment, but studies of the iliac crest are lacking. The purpose of this study was to investigate the strength of the pin-bone interface of different pins and different insertion methods. Four types of commercial pins, Wagner pins, Orthofix cortical and cancellous screws, and AO pins, were driven into sheep iliac crests by 2 methods: the intercortical and the transcortical. Specimens were tested for pullout and bending with an Instron testing machine (Model 1343) at a extension rate of 0.02 mm/sec to failure. The results revealed that the intercortical method had a stronger pullout force than the transcortical in all types of screws (p < 0.05), probably caused by longer insertion in the bone. In the pullout tests, the Wagner pins were the strongest and the Orthofix cancellous screws were the weakest. There were no differences in bending. In the iliac crest, the intercortical method was the better way of driving pins, and the new Orthofix screws were not proven to be stronger than the Wagner pins, nor were the cancellous screws more suitable than the cortical ones.

Animals↗

PubMed1995

[Application and evaluation of multiple exposure photography and motion analysis system in gait measurement].

Accurate techniques to evaluate and quantitate gait patterns have been available in clinical applications for the last 20 years. In this study, by employing multiple exposure photography, the walking velocity, stride length, step cadence and joint angle of the lower limbs were recorded for normal young men during the gait cycle. Data were compared with results from the motion analysis system and related researches. The results showed that multiple exposure photography can also provide quantitative analysis of several important time-distance parameters in the gait cycle.

Adult↗