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Satisfaction of search in osteoradiology.

OBJECTIVE: "Satisfaction of search" describes a situation in which the detection of one radiographic abnormality interferes with that of others. This phenomenon has not been investigated for the interpretation of skeletal radiographs. We determined whether satisfaction of search occurs in the interpretation of conventional radiographs of the musculoskeletal system. SUBJECTS AND METHODS: Twelve volunteers from radiology (10 residents and two staff members) and 13 volunteers from orthopedic surgery (all residents) were shown in random order 15 cases in which one abnormality was present and 15 cases in which either two or three abnormalities were present. The cases with multiple findings contained a total of 19 abnormalities. All cases were selected from the emergency department. The volunteers received three scores reflecting their ability to detect abnormalities on a single-finding case, at least one abnormality on a multiple-finding case, and additional findings in cases with multiple abnormalities. The scores were compared using the chi-square test with Yates correction. Analysis of variance and Bonferroni adjustment were also performed. RESULTS: Among the cases with single findings, detection rates averaged 11.25; for the 15 multiple-finding cases, the detection rate for one finding averaged 11.72. The difference was not statistically significant. Detection rates for the second and third abnormalities in the multiple-finding cases were significantly lower, averaging 6.12 (p < 0.01). CONCLUSION: A significant satisfaction of search effect occurred and was operative in the interpretation of radiographs of the musculoskeletal system.

Bone Diseases↗

Dynamics of muscle function during locomotion: accommodating variable conditions.

Much of what we know about animal locomotion is derived from studies examining animals moving within a single, homogeneous environment, at a steady speed and along a flat grade. As a result, the issue of how musculoskeletal function might shift to accommodate variability within the external environment has remained relatively unexplored. One possibility is that locomotor muscles are differentially recruited depending upon the environment in which the animal is moving. A second possibility is that the same muscles are recruited, but that they are activated in a different manner so that their contractile function differs according to environment. Finally, it is also possible that, in some cases, animals may not need to alter their musculoskeletal function to move under different external conditions. In this case, however, the mechanical behavior appropriate for one environmental condition may constrain locomotor performance in another. To begin to explore the means by which animals accommodate variable conditions in their environment, we present three case studies examining how musculoskeletal systems function to allow locomotion under variable conditions: (1) eels undulating through water and across land, (2) turkeys running on level and inclined surfaces, and (3) ducks using their limbs to walk and to paddle. In all three of these examples, the mechanical behavior of some muscle(s) involved in locomotion are altered, although to different degrees and in different ways. In the running turkeys, the mechanical function of a major ankle extensor muscle shifts from contracting isometrically on a flat surface (producing little work and power), to shortening actively during contraction on an uphill gradient (increasing the amount of work and power generated). In the ducks, the major ankle extensor undergoes the same general pattern of activation and shortening in water and on land, except that the absolute levels of muscle stress and strain and work output are greater during terrestrial locomotion. In eels, a transition to land elicits changes in electromyographic duty cycles and the relative timing of muscle activation, suggesting some alteration in the functional mechanics of the underlying musculature. Only by studying muscle function in animals moving under more variable conditions can we begin to characterize the functional breadth of the vertebrate musculoskeletal system and understand more fully its evolutionary design.

Animals↗

Drug prescribing patterns in Parkinson's disease: a pharmacoepidemiological survey in a cohort of ambulatory patients.

PURPOSE: Drug treatment of idiopathic Parkinson's disease (IPD) is a difficult task, and comorbidity and comedication add to its complexity. Since in IPD there is little information about drug use, this study investigated drug prescribing and indications in IPD patients. METHODS: From June 1997 to April 1998, a cross-sectional survey of IPD outpatients was performed and demographic and clinical data and information about drug treatments was collected and analysed. RESULTS: In the 130 IPD patients included in the study, anti-Parkinson drug (APD) prescriptions increased with disease duration and severity. Levodopa was most frequently used, followed by dopamine agonists and anticholinergic agents. Levodopa with other APDs was given to older patients with later IPD onset. Prescriptions of drugs for other indications (non-APDs) were given to 80.8% of the patients and their number increased with patient age. Non-APD prescriptions concerned mainly the circulatory system, mental disorders, the musculoskeletal system and the digestive system. Prescriptions for indications corresponding to secondary symptoms that often complicate IPD increased with patient age and also with IPD duration. CONCLUSION: In IPD patients, disease duration and severity and patient age seem to be major determinants of drug use. Indications for drug prescription suggest that main comorbidity includes neuropsychiatric, circulatory, musculoskeletal and digestive disorders. Analysis of prescribing patterns in IPD can provide a readily accessible indirect indicator of patient health status for both health services and epidemiologic research purposes.

Adult↗

Three-dimensional representation of complex muscle architectures and geometries.

Almost all computer models of the musculoskeletal system represent muscle geometry using a series of line segments. This simplification (i) limits the ability of models to accurately represent the paths of muscles with complex geometry and (ii) assumes that moment arms are equivalent for all fibers within a muscle (or muscle compartment). The goal of this work was to develop and evaluate a new method for creating three-dimensional (3D) finite-element models that represent complex muscle geometry and the variation in moment arms across fibers within a muscle. We created 3D models of the psoas, iliacus, gluteus maximus, and gluteus medius muscles from magnetic resonance (MR) images. Peak fiber moment arms varied substantially among fibers within each muscle (e.g., for the psoas the peak fiber hip flexion moment arms varied from 2 to 3 cm, and for the gluteus maximus the peak fiber hip extension moment arms varied from 1 to 7 cm). Moment arms from the literature were generally within the range of fiber moment arms predicted by the 3D models. The models accurately predicted changes in muscle surface geometry over a 55 degrees range of hip flexion, as compared to changes in shape predicted from MR images (average errors between the model and measured surfaces were between 1.7 and 5.2 mm). This new framework for representing muscle will enhance the accuracy of computer models of the musculoskeletal system.

Adult↗

Musculoskeletal and systemic reactions to biological therapeutic agents.

Autoimmune disease, in particular systemic lupus erythematosus (SLE), can be induced by drugs. Over the past couple of years biologic agents have become available for the treatment of inflammatory disease; simultaneously, researchers have realized that these drugs can not only suppress autoimmune disease but may also potentiate it. Interferon-alpha and interferon-beta both may induce autoimmune disease, but this is more frequent with interferon-alpha. Therapy to block tumor necrosis factor-alpha, either with monoclonal antibodies or fusion proteins, has been associated with the development of antinuclear antibodies, but only rarely with clinical development of SLE. None of the three reported cases of SLE occuring after anti-tumor necrosis factor-alpha therapy has developed major organ involvement. The continued use of biologic agents will provide interesting insights into the pathogenesis of autoimmune disease.

Antibodies, Monoclonal↗

Non-traumatic thoracic emergencies: acute chest pain: diagnostic strategies.

Acute chest pain may represent the initial and/or accompanying symptom in a variety of disease processes that may occur in the cardiovascular system, respiratory system, gastrointestinal tract, or musculoskeletal system. Although clinical history, risk factors, and physical examination are important factors in establishing the etiology of symptoms in patients presenting with acute chest pain, imaging modalities are frequently utilized. Noncardiac causes of acute chest pain are reviewed in this paper with special reference to the most recently published literature and emphasis on acute aortic diseases. Imaging modalities with indication of appropriateness, optimal technique and practical keys for interpretation are discussed.

Acute Disease↗

Individual muscle force estimations using a non-linear optimal design.

In order to estimate individual muscle forces during human movement a mathematically underdetermined system, representing the human musculoskeletal system, was solved using a non-linear optimization algorithm. The load sharing between muscles was made to depend upon the instantaneous contractile conditions of the muscles, a feature not incorporated in comparable non-linear optimal designs reported in the literature. The optimization algorithm was formulated as a convex system which guarantees a unique solution at the global minimum. The strengths and weaknesses of the present optimization algorithm were evaluated and compared to the classical algorithm reported by Crowninshield and Brand (J. Biomech., 14 (1981) 793-801).

Humans↗

A close look at early embryonic development with the high-frequency transvaginal transducer.

Transabdominal sonography has been, for the past two decades, used as an effective diagnostic and research tool in obstetrics. It is predominantly used in the second and third trimesters of gestation. Its use in the first trimester is relatively limited and mostly diagnostic in nature. The introduction of the higher frequency transvaginal transducer probe, with its higher resolution of the images, opens new possibilities to study early gestation. We studied embryonic development in 38 well-dated and normal pregnancies. A well-defined intrauterine gestational sac could be seen at 4 weeks and 1 to 4 days of menstrual age. The beta-subunit of human chorionic gonadotropin level at this time was 450 to 750 mlU/ml. Structures such as the yolk sac, membranes, ventricular system in the brain, musculoskeletal system, and cord were described and illustrated. Textbooks and atlases were used for comparative purposes. High-resolution transvaginal sonography will facilitate first-trimester perinatology.

Embryo, Mammalian↗

Self-tuning Optimal Regulation of Respiratory Motor Output by Hebbian Covariance Learning.

The respiratory motor system is a specialized musculoskeletal system that is controlled by a small assembly of neuronal clusters in the brainstem. Its prime function is to maintain CO(2), O(2), and pH homeostasis in arterial circulation through the motor act of breathing. A longstanding dilemma is that during muscular exercise homeostatic regulation occurs automatically without any apparent feedback or feedforward signals, whereas the homeostasis is readily abolished by exogenous chemical challenge. Recently, it has been proposed that these seemingly incongruous behaviors of the respiratory controller may be a manifestation of self-tuning adaptive control. This hypothesis is supported in part by recent discoveries of various memory systems in the brainstem controller including short- and long-term potentiation and depression of synaptic transmission as well as the dramatic abolishment of homeostatic regulation in mutant mice with targeted genetic disruption of the NMDA receptors. In this paper, we propose a model of self-tuning homeostatic regulation based upon a synaptic adaptation rule-Hebbian covariance learning rule-that has been suggested to underlie many forms of learning and memory in the higher brain. We show that such an adaptation rule may be a useful neuronal substrate for reinforcement learning in optimization tasks. The model demonstrates how spontaneous oscillations and/or random-like fluctuations of neural activity may be exploited by the controller to adaptively regulate and optimize motor output. Such a self-tuning neural control paradigm, which operates without the need for any internal model of the external environment, is generally applicable to a class of steady-state optimal regulation problems with infinite time horizon. An interesting implication of the present results is that brain intelligent control can occur at a subconscious level without the need for voluntary intervention from the higher brain. Copyright 1996 Elsevier Science Ltd.

Journal Article↗

Unusual neonatal presentation of incontinentia pigmenti with persistent pulmonary hypertension of the newborn: a case report.

Incontinentia pigmenti (Bloch-Sulzberger syndrome) is a multisystem disorder with classical changing skin lesions. The other systems that are involved include the central nervous system, eye, hair, teeth, musculoskeletal system and, occasionally, the cardiovascular system. We report a neonate with a diagnosis of incontinentia pigmenti who presented at birth with pulmonary hypertension. This presentation has not been described in the literature.

Fatal Outcome↗

Adenoviral gene transfer restores lysyl hydroxylase activity in type VI Ehlers-Danlos syndrome.

Type VI Ehlers-Danlos syndrome is a disease characterized by disturbed lysine hydroxylation of collagen. The disease is caused by mutations in lysyl hydroxylase 1 gene and it affects several organs including the cardiovascular system, the joint and musculoskeletal system, and the skin. The skin of type VI Ehlers-Danlos syndrome patients is hyperelastic, scars easily, and heals slowly and poorly. We hypothesized that providing functional lysyl hydroxylase 1 gene to the fibroblasts in and around wounds in these patients would improve healing. In this study we tested the feasibility of transfer of the lysyl hydroxylase 1 gene into fibroblasts derived from rats and a type VI Ehlers-Danlos syndrome patient (in vitro) and into rat skin (in vivo). We first cloned human lysyl hydroxylase 1 cDNA into a recombinant adenoviral vector (Ad5RSV-LH). Transfection of human type VI Ehlers-Danlos syndrome fibroblasts (about 20% of normal lysyl hydroxylase 1 activity) with the vector increased lysyl hydroxylase 1 activity in these cells to near or greater levels than that of wild type, unaffected fibroblasts. The adenoviral vector successfully transfected rat fibroblasts producing both beta-galactosidase and lysyl hydroxylase 1 gene activity. We next expanded our studies to a rodent model. Intradermal injections of the vector to the abdominal skin of rats produced lysyl hydroxylase 1 mRNA and elevated lysyl hydroxylase 1 activity, in vivo. These data suggest the feasibility of gene replacement therapy to modify skin wound healing in type VI Ehlers-Danlos syndrome patients.

Adenoviridae↗

BILAG 2004. Development and initial validation of an updated version of the British Isles Lupus Assessment Group's disease activity index for patients with systemic lupus erythematosus.

OBJECTIVE: To devise a more discriminating version of the British Isles Lupus Assessment Group (BILAG) disease activity index and to show that it is reliable. METHODS: A nominal consensus approach was undertaken by members of BILAG to update and improve the BILAG lupus disease activity index. The index has been revised following intense consultations over a 1-yr period. It has been assessed in two real-patient exercises. These involved patients with diverse clinical features of SLE, including gastrointestinal, hepatic and ophthalmic problems, which the earlier versions of the index did not fully take into account. Reliability in terms of the ability to differentiate patients was assessed by calculating intraclass correlation coefficients. The level of agreement between physicians was determined by calculating the ratio of estimates of the standard error (SE) attributable to the physicians to the SE attributable to the patients. RESULTS: Good reliability and high levels of physician agreement were observed in one or both exercises in the constitutional, mucocutaneous, neurological, cardiorespiratory, renal, ophthalmic and haematological systems. In contrast, the musculoskeletal system did not score as well, although providing more clear-cut glossary definitions should greatly improve the situation. CONCLUSIONS: Some significant changes in the BILAG disease activity index to assess patients with SLE are proposed. The process of demonstrating validity and reliability has started with these two exercises assessing real patients. Further validation studies are under way. BILAG 2004 is likely to be valuable in clinical trials assessing new therapies for the treatment of SLE, as it provides a more comprehensive system-based disease activity measure than has been available previously.

Adult↗

Brain death in the pediatric patient: historical, sociological, medical, religious, cultural, legal, and ethical considerations.

OBJECTIVE: To detail the origins of the definition of death, the development of the criterion of whole brain death as fulfilling the definition of death, and the tests used to fulfill that criterion. DATA SOURCES: A review of the literature was performed. No Institutional Review Board approval was necessary. DATA EXTRACTION: In 1959, patients were described as being in "coma dépassé" or beyond coma. In 1967, the first successful heart transplantation took place, with the organ coming from a brain-dead, beating-heart donor. However, anxiety over the definitions of death did not begin with the modern, technological era, and death itself has never been definable in objective terms. It has always been a subjective and value-based construct. During ancient times, most people agreed that death occurred when a person's heartbeat and breathing stopped. For the Greeks, the heart was the center of life; for the ancient Hebrews and Christians, the breath was the center of life. In the 12th century, Maimonides pointed toward the head, and the loss thereof, as the reason for lack of central guidance of the soul. Physicians neither diagnosed nor certified death. During the Enlightenment, the necessity of heartbeat, breath, and consciousness for the definition of life was questioned, leading to questioning regarding the definition of death. Tests to fulfill the criteria of death, and tests to determine the absence of integration between functions of respiration, circulation, and neurology were introduced. Sensorimotor potential was becoming recognized as defining life, rather than heartbeat and respiration. As new tests were devised to fulfill criteria of death, the physician developed a professional monopoly on meeting the criteria of brain death. In the modern era, the boundary between life and death has been blurred, but the intensive care unit straddles this boundary. We may have situations where the patient is alive but in a coma, without functioning heart, lungs, kidneys, or gastrointestinal tract, with a transplanted liver, a reversed coagulation system, a blocked immune system, and a paralyzed musculoskeletal system. DATA SYNTHESIS: A human being is a man, woman, or child who is a composite of two intricately related but conceptually distinguishable components: the biological entity and the person. Therefore, human beings can suffer more than one death: a biological death and decay, and another death. Biological death is a cessation of processes of biological synthesis and replication, and is an irreversible loss of integration of the biological units. The reasons for having criteria for death are to diagnose death and pronounce a person dead. Society can then begin to engage in grief, religious rites, funerals, and burials, and accept biological death. Wills can be read, property distributed, insurance claimed, individuals can remarry, succession can take place, and legal proceedings can begin. Also, organ donation can take place, which entails difficult ethical decisions. The Harvard criteria of 1968 were devised to set forth brain-death criteria with whole brain death in mind. Currently, there are several controversies regarding these criteria: a) whether they apply to infants and children; b) whether ancillary tests are necessary; c) what the intervals of observation and testing are; and d) are there exceptions to the whole brain death criteria. Concerning the use of the adult criteria for infants and children, most researchers now agree that the adult criteria apply to infants and children who are full term and > 7 days of age. Concerning ancillary tests, there has been, in our machine- and technology-oriented profession, a great deal of emphasis on the different tests and their ability to fulfill the criteria of whole brain death. However, clinical examination and the apnea test are usually sufficient to fulfill the criteria. Ancillary tests may be desired in some cases, and a variety of these tests is available. (ABSTRACT TR

Adult↗

Complications of laparoscopic nephrectomy in 185 patients: a multi-institutional review.

PURPOSE: We document the incidence of complications associated with laparoscopic nephrectomy in a multi-institutional study. MATERIALS AND METHODS: The study included the initial 185 patients undergoing laparoscopic nephrectomy at 5 centers in the United States between June 1990 and July 1993. RESULTS: A total of 30 patients (16%) had 34 complications. There was no mortality. Access-related complications included 2 cases of hernia formation at the trocar site, 1 abdominal wall hematoma and 1 trocar injury to a hydronephrotic kidney. Intraoperative complications included 5 cases of vascular injury, 1 splenic laceration and 1 pneumothorax. Postoperative complications involved the gastrointestinal tract in 6 cases, cardiovascular system in 6, genitourinary tract in 4, respiratory system in 4 and musculoskeletal system in 2. Miscellaneous complications occurred in 3 patients. Open surgical intervention was required electively in 8 patients and on an emergency basis in 2. The incidence of complications decreased with experience: 71% occurred during the initial 20 cases at each institution. CONCLUSIONS: In our early experience the complication rate for laparoscopic nephrectomy was 12% in patients with benign renal disease and 34% in those with renal cancer. Based on this collective experience, recommendations for prevention, recognition and treatment of complications are made.

Adult↗

Sensory deprivation and homeostasis.

Most afferent inputs are sensory stimulants, and physical activity is probably one of the most significant of all sensory stimulations. Gravity is a constant stimulus. These demands are also known as stress, and the stressor effect as the general adaptation syndrome (Selye). In this study, these demands are called sensory afferent stimuli, which are necessary triggers to start the hypothalamus-pituitary-adrenal mechanism and thus maintain the general mechanical, autonomic and metabolic functions of the body in the state of homeostasis. If the sensory stimulus is removed, there is no stressor effect and the cycle of response is eliminated. This results in a decreased hypothalamus-pituitary response and a decreased production of ACTH and corticoids. A decrease in the sensory input creates changes in the central nervous system and in the musculoskeletal system which are compatible with lack of the hypothalamus-pituitary responses. When a person becomes ill, physical inactivity as well as sensory and perceptual deprivation are at a maximum, and the absence of these stimuli interrupts the cycle of homeostasis. Physical activity is one of the most important stressors (sensory input) or triggering mechanisms for the cycle of homeostasis (hypothalamus-pituitary-adrenal cycle). Therefore, it is imperative to provide the patient with physical activities which ensure motion and take into account the effect of gravity. This is best accomplished by a program of physical, occupational and recreational therapy.

Aged↗

Probing the limits to muscle-powered accelerations: lessons from jumping bullfrogs.

The function of many muscles during natural movements is to accelerate a mass. We used a simple model containing the essential elements of this functional system to investigate which musculoskeletal features are important for increasing the mechanical work done in a muscle-powered acceleration. The muscle model consisted of a muscle-like actuator with frog hindlimb muscle properties, operating across a lever to accelerate a load. We tested this model in configurations with and without a series elastic element and with and without a variable mechanical advantage. When total muscle shortening was held constant at 30%, the model produced the most work when the muscle operated with a series elastic element and an effective mechanical advantage that increased throughout the contraction (31 J kg(-1) muscle vs 26.6 J kg(-1) muscle for the non-compliant, constant mechanical advantage configuration). We also compared the model output with the dynamics of jumping bullfrogs, measured by high-speed video analysis, and the length changes of the plantaris muscle, measured by sonomicrometry. This comparison revealed that the length, force and power trajectory of the body of jumping frogs could be accurately replicated by a model of a fully active muscle operating against an inertial load, but only if the model muscle included a series elastic element. Sonomicrometer measurements of the plantaris muscle revealed an unusual, biphasic pattern of shortening, with high muscle velocities early and late in the contraction, separated by a period of slow contraction. The model muscle produced this pattern of shortening only when an elastic element was included. These results demonstrate that an elastic element can increase the work output in a muscle-powered acceleration. Elastic elements uncouple muscle fiber shortening velocity from body movement to allow the muscle fibers to operate at slower shortening velocities and higher force outputs. A variable muscle mechanical advantage improves the effectiveness of elastic energy storage and recovery by providing an inertial catch mechanism. These results can explain the high power outputs observed in jumping frogs. More generally, our model suggests how the function of non-muscular elements of the musculoskeletal system enhances performance in muscle-powered accelerations.

Animals↗

Hunter syndrome: case report and review of literature.

Hunter syndrome is one of the mucopolysaccharidosis, which are a rare group of genetic diseases. It is due to a deficiency in the enzyme Iduronate 2-sulphatase. This in turn leads to the accumulation of glycosaminoglycans, dermatan and heparan sulphate. The intra and extracellular accumulation of this substances lead to multisystemic organ abnormality. We present a patient with Hunter syndrome who presented with involvement of the skin, cardiovascular system, the eyes and musculoskeletal system. We have also included a literature review. As far as we know, it is the first case reported in a Nigerian.

Adolescent↗

Physical health status of pupils in a school for the mentally disabled in Lagos.

The study set out to assess the health status of pupils of a school for children with mental disability. The school is Modupe Cole Memorial Child Care and Treatment Home School, Akoka, Lagos. The records of 211 pupils were reviewed and the pupils were clinically examined by the author. Seventy-four (35.1%) of the subjects had complete immunization, 48(22.7%) had incomplete immunization while 44(20.9%) received no immunization. The probable aetiology of mental disability in the subjects was due to postnatal causes (96; 45.5%), natal causes (44; 20.8%), prenatal causes (12; 5.7%) and unknown (59; 28.0%). The most abnormal findings on physical examination were in the central nervous system (199; 94.3%), the musculoskeletal system (137; 64.9%), the mouth/teeth (125; 59.2%) and the skin (98; 46.4%). These findings were worse amongst the residential students than in the non-residential students (p < 0.001). The information obtained from this study will help to serve as a reference for purposes of health planning and policy formulation for children with mental disability.

Adolescent↗