Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two hundred and ninety-five male Finnish concrete reinforcement workers, aged 19 to 64 years and engaged in heavy physical work including prolonged stooping, were radiologically examined by antero-posterior and lateral views of the lumbar spine while they were standing. The findings of lumbar disc degeneration were classified as none, slight, moderate or severe. The prevalence and degree of radiologically detectable lumbar disc degeneration depended strongly on age and increased especially rapidly from 40 to 44 years on. Lumbar disc degeneration showed an age-independent association to both a history of lumbago (chi2 = 10.5, p less than 0.01) and a history of sciatica (chi2 = 11.8, p less than 0.001). When disc degeneration was compared to reports of stiffness, fatigue, ache, and sharp pain in the back during an ordinary workday, no statistically significant associations were found, while disc degeneration was found to be slightly more common (chi2 = 4.6, p less than0.05) in the men reporting back symptoms as they bent down than in the men who did not report such symptoms. No association between length of exposure to static and dynamic back loads in reinforcement work and the prevalence of lumbar disc degeneration could be established, but definite conclusions on the possible effect of reinforcement work on the lumbar spine could not be drawn from the data.
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PMID:Radiologically detectable lumbar disc degeneration in concrete reinforcement workers. 66 71

Seventeen cadaveric human lumbar motion segments from eight spines were cyclically loaded in vitro under axial compression. Loading frequency and magnitude were chosen to simulate rigorous activity within an in vivo physiological level. The load magnitude was determined as a percentage of the ultimate compressive load, the latter estimated from the bone mineral content (BMC) of lumbar vertebrae determined by dual-photon absorptiometry. Following testing, the degree of macroscopic disc degeneration was assessed and the type of fracture in each specimen was determined from serial sagittal sections. Fractures were found in all but one specimen. Three types of fractures were formed: the node of Schmorl and Junghanns (type I), central endplate fracture (type II), and a crush or burst fracture (type III). The results suggested that type I fractures were predominantly associated with segments with normal discs, type II fractures were found primarily in segments with moderately degenerated discs, and type III fractures were associated with segments that failed on the first cycle. Segment stiffness and fatigue strength (cycles to failure) were correlated with disc degeneration, age, and segment BMC, the latter an in vivo measure of bone density. Fatigue strength also decreased in proportion to a power coefficient with increasing relative stress (cyclic stress range/ultimate stress).
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PMID:Mechanical behavior of the human lumbar spine. II. Fatigue strength during dynamic compressive loading. 368 22

Although the epidemiologic evidence is not convincing, a number of studies indicate that those exposed to dynamic loads may have increased risk to low-back disorders. A review of the available evidence suggests that chronic low-back pain relates to disc degeneration and that this in turn may be accelerated by mechanical failure in the region of the end-plate and subchondral bone or in the annulus. Two hypotheses are proposed to relate fatigue induced failure of vertebral tissues to disc degeneration. The extent of dynamic stresses on the vertebral motion segment arising from transport are investigated, and the results indicate that fatigue induced failure is a distinct possibility. The implications of these suggestions for environmental health protection are briefly discussed.
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PMID:Dynamic loading as a possible source of low-back disorders. 622 22

A relationship between disc lesion and microdamage accumulation in adjacent vertebrae during fatigue loading was investigated in a canine model. Eighteen functional spinal units obtained from 6 skeletally mature mongrel dogs were divided into 3 groups: I, control (without loading) (n = 6); II, loading with normal disc (n = 6); and III, loading with disc lesion created by nucleotomy (n = 6). Physiologic cyclic compression was performed for 10(5) cycles, and fractional trabecular bone area and microcrack density in the vertebrae were measured. There was a significant difference in microcrack density among groups and regions (p < 0.0001) with significantly more microdamage in functional spinal units with disc lesions than in the other 2 groups (p < 0.0001). The microcracks were distributed predominantly in the vertebral region adjacent to the nucleotomized disc (p < 0.005). There was a negative association of microcrack density with fractional trabecular bone area (R2 = 0.236, p < 0.02). These results support the hypothesis that disc degeneration contributes to vertebral fragility by causing microdamage accumulation, especially in vertebrae with low bone mass.
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PMID:Effect of disc lesion on microdamage accumulation in lumbar vertebrae under cyclic compression loading. 763 75

Human intervertebral discs undergo age-related degenerative changes that contribute to some of the most common causes of impairment and disability for middle aged and older persons: spine stiffness, neck pain, and back pain. Potential causes of the age-related degeneration of intervertebral discs include declining nutrition, loss of viable cells, cell senescence, post-translational modification of matrix proteins, accumulation of degraded matrix molecules, and fatigue failure of the matrix. The most important of these mechanisms appears to be decreasing nutrition of the central disc that allows accumulation of cell waste products and degraded matrix molecules, impairs cell nutrition, and causes a fall in pH levels that further compromises cell function and may cause cell death. Although aging changes of the disc appear to be inevitable, identification of activities and agents that accelerate these changes may help decrease the rate and severity of disc degeneration; and recent work suggests that methods can be developed that will regenerate disc tissue.
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PMID:Aging and degeneration of the human intervertebral disc. 766 Feb 43

Competitive swimmers perform highly repetitive motions, therefore characteristic overuse injuries of the shoulder, back, and knee can occur. A thorough history and examination should be performed by both physician and physical therapist. The combination of hypovascularity, fatigue, poor stroke mechanics, and the progressive instability of a hypermobile joint results in shoulder impingement. Medical evaluation should determine the existence of any glenohumeral joint instability or signs of impingement. Back injuries are most commonly due to disc degeneration, hyperextension, or myofascial involvement. Medial knee pain is most common in breaststroke swimmers and may be due to excessive valgus and rotatory stress. Frequently seen diagnosis includes patellofemoral pain, medial collateral ligament stress syndrome, and medial synovitis. Treatment will focus on elimination of inflammation. Rehabilitation should focus on stabilisation exercises for hypermobile joints, postural correction, strengthening and flexibility.
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PMID:Rehabilitation of injuries in competitive swimmers. 892 51

Regulations concerning the work environment, tools, and the performance of work are at their best based on scientific evidence. Existing European directives, European and North American standards, and recent guidelines with the potential to prevent musculoskeletal disorders, are either qualitative or semiquantitative. The exception is the NIOSH lifting guide, which is highly quantitative. Of the European directives and standards, few have been developed with the primary goal of preventing musculoskeletal disorders, whereas one North American standard and another suggestion for a standard have this specific aim. In a review of epidemiological studies on low-back, neck, shoulder, and upper extremity disorders, several physical load factors were identified as risk factors for the disorders. Many of these factors have been repeatedly identified, and for different types of outcomes of an anatomical area (e.g. pain, disc herniation, disc degeneration of the low-back or neck). However, quantitative exposure-response relationships between physical load factors and disorders based on field studies are largely unknown. Experimental studies have provided a multitude of potentially useful data. It is concluded that both well-designed epidemiological studies with quantitative assessments of physical work load and valid measurements of musculoskeletal disorders, and experimental studies are needed for the future development of regulation. To determine the role of experimental studies in regulation, it should be known to what extent fatigue and other short-term responses are precursors of disorders. Regulation should be directed especially towards factors that are likely to be causative for musculoskeletal disorders. Examples of such factors are sudden overload in manual handling activities, heavy physical work involving manual handling tasks, and vibration from tools. Guidelines that are acceptable and feasible can and should be developed. The effects of such guidelines on the occurrence of musculoskeletal disorders should be investigated.
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PMID:The scientific basis for making guidelines and standards to prevent work-related musculoskeletal disorders. 933 42

Classic degenerative disc disease is a serious health problem worldwide, whose etiological basis-mechanical stimulus, biochemical changes, or natural aging-is poorly understood. Animal models are critical to the study of degenerative disc disease initiation and progression and for attempts to regulate, ameliorate, or eliminate it. The macaque represents a primate model with natural disc degeneration that might serve to advance the field; we aimed to provide radiographic (morphologic) and biomechanical evidence of natural disc degeneration in this model. A factorial study design was used to examine the relationship between the radiographic appearance of disc degeneration and its biomechanical consequences. Eighteen macaques of advanced age (22.3 +/- 0.9 years) had radiographs taken to assess the degree of thoracolumbar intervertebral disc degeneration using a standard atlas method. Each spine was harvested and dynamic biomechanical tests were performed. Advancing disc degeneration (degree of disc space narrowing and osteophytosis) was associated with increased stiffness, decreased energy absorption, and increased natural frequency of the intervertebral disc. These associations linking the dynamics of the intervertebral disc and its degree of degeneration are similar to those found in humans. Our results indicate the macaque model with morphologic and biomechanical efficacy could aid in understanding the progression of disc degeneration and in developing therapeutic strategies to prevent or inhibit its course.
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PMID:Intervertebral disc degeneration in a naturally occurring primate model: radiographic and biomechanical evidence. 1840 51

Current treatments for intervertebral disc degeneration and herniation are palliative only and cannot restore disc structure and function. Nucleus pulposus (NP) replacements are a promising strategy for restoring disc biomechanics and height loss. Cellulose-based hydrogel systems offer potential for NP replacement since they are stable, non-toxic, may be tuned to match NP material properties, and are conducive to cell or drug delivery. A crosslinked, carboxymethylcellulose-methylcellulose dual-polymer hydrogel was recently formulated as an injectable NP replacement that gelled in situ and restored disc height and compressive biomechanical properties. The objective of this study was to investigate the translational potential of this hydrogel system by examining the long-term structural stability in vitro, the herniation risk and fatigue bending endurance in a bovine motion segment model, and the in vivo biocompatibility in a rat subcutaneous pouch model. Results showed that the hydrogels maintained their structural integrity over a 12-week period. AF injury significantly increased herniation risk and reduced fatigue bending endurance in bovine motion segments. Samples repaired with cellulosic hydrogels demonstrated restored height and exhibited herniation risk and fatigue endurance comparable to samples that underwent the current standard treatment of nucleotomy. Lastly, injected hydrogels elicited a minimal foreign body response as determined by analysis of fibrous capsule development and macrophage presence over 12 weeks. Overall, this injectable cellulosic hydrogel system is a promising candidate as an NP substitute. Further assessment and optimization of this cellulosic hydrogel system in an in vivo intradiscal injury model may lead to an improved clinical solution for disc degeneration and herniation.
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PMID:Injectable cellulose-based hydrogels as nucleus pulposus replacements: Assessment of in vitro structural stability, ex vivo herniation risk, and in vivo biocompatibility. 3105 15