Comments on the paper 'Monte Carlo simulation of source-excited in vivo x-ray fluorescence measurements of heavy metals'.
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Bone and Bones↗
Biomedical subjects
J E Fernandez
Publications and source records attributed to J E Fernandez.
Kienböck's disease. I. Anatomy and Etiology.
Cumulative trauma disorders (CTD) pose a major industrial problem in terms of increased medical costs, lost productivity and degraded worker health and safety. From an anatomical view, CTD's are classified into three major categories: tendon disorders, neurovascular disorders and nerve disorders. Up until recently these categories seemed to cover CTD of the upper extremity, however, Kienböck's disease, a typically less common disease and one that does not fit into the established CTD categories, has been observed to exhibit CTD characteristics and does appear in the manufacturing environment. The most common types of employment observed to exhibit individuals with this disease are carpentry, jobs involving the use of pneumatic tools (wrench), spot welders, sheet metal work, farmers and factory workers. The present article makes a critical examination of the relevant anatomy and etiologic aspects of this disease.
Cumulative Trauma Disorders↗
Kienböck's disease. II. Risk factors, diagnosis, and ergonomic interventions.
The term CTD has been used to refer to those musculoskeletal impairments that appear to be work-related and tend to be chronic. Upper extremity CTD are categorized in three major groups: tendon disorders, neurovascular disorders, and nerve. Kienböck's disease, on the other hand, has been documented in the workplace and has a similar etiology, but due to current anatomic classifications cannot be considered a CTD. With this in mind, the present article reviews risk factors, diagnosis, and treatment, with the purpose of providing physicians, engineers, and designers with information to reduce the risk of workers developing this potentially debilitating disease. Furthermore, additional support will be accumulated and combined with Part I of this article with the intent of introducing into the literature a new category of upper extremity CTD: Bone Disorders.
Ergonomics↗
The effect of music amplitude on the reaction to unexpected visual events.
The effects of music amplitude on participants' response time to randomly presented, unexpected, visual events were investigated. Ninety participants completed a motor-reaction task without music and with music played at 60, 70, or 80 dBA. Males preferred more intense music than females did, with males selecting a comfort level of 72 dBA and females, 66 dBA. However, participants' reaction time and the total time to respond to a randomly activated red light were independent of gender. All participants responded more quickly when the music was played at 70 dBA (close to their comfort level) than when it played at lower (60 dBA) or higher (80 dBA) amplitudes. It is proposed that people may react more quickly to visual events (e.g., the sudden appearance of a plane on the screen of an air traffic controller, or the unpredictable activation of a car's rear brake lights when driving) with music playing at a volume preset to maintain individual comfort levels against other situational background noise.
Adolescent↗
Design-oriented functional capacity evaluation: the available motions inventory--a review.
The accommodation of a task to the unique abilities of an individual with a disability is becoming increasingly the responsibility of the employer. Functional capacity evaluation (FCE) provides the information necessary for rational design decisions when modifying work stations. The currently used FCE systems have been designed to assess an individual's performance for a range of reasons other than industrial task accommodation. The Available Motions Inventory (AMI) is a system that has been developed specifically to address the design issues raised when accommodating an industrial task to a person with a neuromuscular impairment. This system has a unique scoring system that allows intra-individual ability comparisons that support task allocation decisions. Some general principles of task design are developed for persons with cerebral palsy, but the strength of assessment lies in its application to a specific individual performing a specific task.
Adult↗
The effect of wrist and arm postures on peak pinch strength.
This paper examines the effect of various arm postures on peak pinch strength. Twenty (20) able-bodied, male subjects volunteered to participate in a set of two experiments. The first experiment examined the effect of shoulder and elbow posture on peak pinch strength. The second experiment examined the effect of forearm posture, wrist posture, and pinch type on peak pinch strength. Results from the first experiment indicated that elbow posture had a significant effect on pinch strength. It was documented that extreme elbow flexion decreased pinch strength by up to 9%. Results from the second experiment indicated that deviated wrist postures, forearm postures, and pinch type significantly decreased pinch strength as much as 33%. Ergonomic guidelines which utilize the above factors as significant modifiers of pinch strength capacity may assist ergonomists to reduce the risk of injury and development of cumulative trauma disorders in the workplace.
Adult↗
Differentiation of a human rhabdomyosarcoma cell line after antineoplastic drug treatment.
The feasibility of treating solid tumours with differentiation therapy using antineoplastic drugs is currently being investigated, but the emergence of multidrug resistance remains the major limitation to this therapeutic approach. A rhabdomyosarcoma cell line resistant to actinomycin D (RD-DAC) has been used as an in vitro model to investigate, with light and electron microscopy, the degree of differentiation in multidrug-resistant cells. The parental cell line (RD), derived from a human embryonic-type rhabdomyosarcoma, is undifferentiated, with no evidence of specific ultrastructural markers. Examination of resistant cells by transmission electron microscopy revealed myofilaments arranged parallel to the long axis of the cell, which was considered clear evidence of myogenic differentiation. These observations suggest that actinomycin D, the drug of choice in the treatment of rhabdomyosarcoma, induces differentiation in the cell line RD. It is postulated that multidrug resistance can interfere with cellular differentiation.
Actin Cytoskeleton↗
Psychophysical frequency and sustained exertion at varying wrist postures for a drilling task.
Two laboratory experiments were conducted; first, to utilize the psychophysical approach (method of adjustment) to establish maximum acceptable frequency (MAF) for a sheet metal drilling task and, second, to examine the effect of sustained, static exertion upon objective and subjective measures under similar task conditions. In both experiments, the wrist posture (flexation, ulnar deviation) required by the task was varied. Twelve healthy females served as subjects. Results show that the psychophysically adjusted task frequency was significantly lower when wrist deviation was required, particularly flexion. MAF for one-third (25 degrees) and two-thirds (50 degrees) flexion were 88% and 73%, respectively, of those selected in the neutral posture. Furthermore, these results were supported by trends in grip strength, heart rate, blood pressure, EMG and perceived exertion. Results from the sustained exertion trials revealed that significant increases in physiological parameters occurred during 3-minute sessions and that this trend was exasperated with deviated wrist posture, particularly flexion. Considering results of both experiments, it was concluded that while the neutral wrist posture may be preferred for a drilling operation, task frequency should be reduced for deviated postures when redesign is not feasible and it is further recommended that deviation be limited to one-third maximum flexion (25 degrees) and two-thirds maximum ulnar deviation (30 degrees). It is also suggested that the psychophysical approach may be utilized to establish 'acceptable' parameters for other industrial tasks involving upper extremity stress, particularly in the current absence of more objective biomechanical and/or physiological criteria for reducing the risk of exposure to cumulative trauma disorders.
Adult↗
Psychophysically acceptable weights for a combination lifting task using bags with handles.
This paper presents a study on a combination lift and lower manual handling task and was designed to simulate the loading of grocery bags into a car trunk. Twelve male subjects performed an externally paced task of lifting grocery bags loaded with weights from 15 cm above the floor and over a wooden sill. There were two different sill heights of 70 cm and 90 cm, and for each of these heights there were two frequencies of 3 and 6 lifts per cycle. The dependent variables were maximum acceptable weight of lift (MAWOL). A unique lifting sequence and a modified version of the psychophysical methodology were used to determine MAWOL. There was a significant difference in the MAWOL across the two sill heights as well as the MAWOL at the two different frequencies. Plastic bags were determined to increase the average load lifted by 27% as compared to paper bags. At normal grocery bag weights, the increased load carrying capacity represents an increase in the safety factor. Not only can the risk of lower back injuries be decreased by using plastic bags with handles but the risk of developing a cumulative trauma disorder could also be decreased.
Adult↗
Maximum acceptable frequencies for females performing a drilling task in different wrist postures.
This paper presents a study on the effect of wrist posture; flexion, extension, ulnar deviation, and radial deviation on maximum acceptable frequencies (MAF) for a drilling task using a psychophysical approach. Twelve females were selected from a college population to serve as subjects and an adjustable workstation was used to simulate a drilling task. The results revealed that flexion, extension, and radial deviation all had a significant effect on MAF but, ulnar deviation did not. The postures have been ranked in order of possible risk of contributing to CTD injury, with neutral having the lowest rank (lowest risk) and flexion having the highest rank (greatest risk).
Adolescent↗
Expression of epidermal growth factor receptor in chick embryo myocardiocytes: relation with desmin expression during cardiac development.
The epidermal growth factor receptor is related with processes of cell replication and differentiation. We used the intermediate filament protein desmin as a marker to study the relation between muscle cell differentiation and modifications in the expression of this receptor during heart development in the chick embryo. Epidermal growth factor receptor was expressed as early as Hamburger and Hamilton's stage 17, when myocardiocytes are still poorly differentiated and desmin-negative. Expression became steadily weaker as the heart matured, and decreased after Hamburger and Hamilton's stage 25, a key stage in heart maturation characterized by a sharp increase in desmin expression. Our findings suggest that in the chick embryo, the expression of epidermal growth factor receptor becomes steadily weaker as myocardiocyte differentiation progresses.
Animals↗
Training of ambulatory individuals with cerebral palsy.
The effect of training on the physical work capacity (PWC) and the physiological response to simulated tasks of seven ambulatory individuals with cerebral palsy (CP) were studied. Energy demand for each work task was determined by percentage of PWC (%PWC). Results indicate that an eight week training program increased the PWC as evaluated by an exercise test on the Schwinn Air-Dyne Ergometer. The performance of the individuals for the simulated tasks measured in %PWC increased significantly, suggesting that individuals with CP could benefit from a training program and would be able to work eight hours before experiencing fatigue.
Adult↗
Actin, tropomyosin and alpha-actinin as markers of differentiation in human rhabdomyosarcoma cell lines induced with dimethyl sulfoxide.
Most rhabdomyosarcomas are poorly differentiated malignant tumors. Dimethyl sulfoxide has been shown to modulate cell differentiation in cultured human cells. We induced differentiation in human rhabdomyosarcoma cell lines A-673, RD and A-204 with 1.25% dimethyl sulfoxide, and used desmin, the protein most frequently used as a marker of muscle cell differentiation, to trace this process. As alternative markers of the degree of differentiation, we quantified the expression of the proteins actin, tropomyosin and alpha-actinin in these cell lines, and followed the changes in expression of these proteins after induction for 8, 12, 24, 48 and 72 hrs. In the process of differentiation, protein expression in both the cytoplasm and cytoskeleton was significantly increased by treatments lasting 12 hrs. (alpha-actinin) and 24 hrs. (actin). On the basis of our results, alpha-actinin can be considered as an earlier marker of differentiation than actin in human rhabdomyosarcoma cell lines. However, the earliest indication of differentiation was a modification in desmin expression (8 hrs.). Because changes in tropomyosin expression were less marked, we consider this protein as a poor marker of rhabdomyosarcoma cell differentiation.
Actinin↗
Production of a new monoclonal antibody recognizing alpha-actinin: analysis of the changes in subcellular expression in the developing chick heart.
A new monoclonal antibody that recognizes alpha-actinin in cardiac muscle cells was used in a quantitative study (fluorescence activated cell sorting and polyacrylamide gel electrophoresis) of the expression of this protein during chick embryo development, to determine the changes in cytoplasmic and cytoskeletal compartments. alpha-Actinin expression was weak in early stages of development (Hamburger and Hamilton stage 18) and increased steadily until Hamburger Hamilton stage 40. In all stages, the protein was more abundant in the cytoplasmic compartment. The monoclonal antibody cross-reacted with alpha-actinin in chicken smooth and striated muscle cells and also showed a faint cross-reaction with human cardiac muscle alpha-actinin.
Actinin↗
Anthropometry of south Indian industrial workmen.
This paper presents the results of an anthropometric survey conducted on South Indian male workers in the electronic industry. The data were collected as part of a project to modify work stations that utilized equipment from other countries. A set of 27 body dimensions were taken from a sample of 128 workmen (aged 18-35 years). The anthropometric measurements are compared with those of Indian men from Central, Western, and Northern parts of India and with those of the American, German, and Japanese men. The results indicate that in general the South Indian man is smaller than Central, Western, and Northern Indian men, as well as smaller than men in America, Germany, Japan, and Africa. This difference needs to be allowed for when considering buying and subsequently using imported equipment for the electronics industry in South India.
Adult↗
Psychophysical lifting capacity over extended periods.
The effect of time on an individual's lifting capacity over extended periods using a psychophysical approach was studied. Twelve male subjects estimated their lifting capacity in a 25 min period, and then attempted to lift this weight for an 8 h period under varying conditions. For one experimental condition the subjects were allowed to adjust the weight, the final adjusted maximum acceptable weight of lift (MAWOL) averaged 85.4% of the original MAWOL determined in the 25 min session. The subjects also attempted to lift for an 8 h period, without any weight adjustments. All 12 subjects lasted the 8 h at 2 lifts per min, but at a frequency of 8 lifts per min only three subjects completed the eight hour lifting task. This indicates that the psychophysical approach is a valid method to measure lifting capacity across the lower lifting frequency range but overestimates the lifting capacity at the higher frequency range. Slight fluctuations were noted in heart rate and oxygen consumption which were recorded every hour.
Adult↗
Physiological capacities of individuals with cerebral palsy.
The physical work capacity (PWC) and the physiological response to stimulated tasks of nine ambulatory individuals with cerebral palsy (CP) were studied. Energy demand for each work task was determined by percentage of PWC (%PWC). Results demonstrated significant differences in energy demand attributed to frequency and mode of lift regardless of gender. No significant difference for energy demand, however, was seen for load lifted. The %PWC for several tasks was near or above the accepted limit for an eight-hour workday, suggesting that the subjects were performing close to their physical limits or higher and would possibly experience fatigue before the eight-hour workday ended. The results also indicated that the PWC of subjects in this study was inferior to that of their nondisabled peers.
Arousal↗