Livres sur le sujet « EFFECT OF STIFFNESS »

Rhabdomyolysis is a potentially life-threatening syndrome characterized by the breakdown of skeletal muscle. It is associated with myalgia, muscle tenderness, swelling, and/or stiffness, accompanied by weakness and raised levels of creatine kinase (CK), myoglobin, phosphate and potassium, sometimes with acute kidney injury (AKI). There are multiple causes of this syndrome, traumatisms and myotoxic effect of drugs being the most frequent in developed countries. The pathophysiology involves direct trauma, as well as energy (ATP) depletion with disruption of sarcolemma integrity and muscle destruction. The sequestration of plasma water leads to hypovolaemic shock, while the release of muscle content, mainly myoglobin and potassium lead to the most severe complications of this syndrome, acute kidney injury/hyperkalaemia. The kidney injury is driven both by renal ischaemia due to vasoconstriction and to the toxic effects of myoglobin. The local oedema produced by the release of muscle content remains trapped within the fascia and can lead to compartment syndrome. Volume repletion with saline is essential to avoid hypovolaemic shock and acute kidney injury (AKI). With respect to compartment syndrome, close monitoring of clinical signs and compartment pressures is essential, since it can evolve to a surgical emergency. The prognosis of rhabdomyolysis is determined by age, baseline conditions and, most importantly, whether or not severe AKI develops.

This book provides readers with a solid understanding of the principles of automobile body structural design, illustrating the effect of changing design parameters on the behavior of automobile body structural elements. Emphasizing simple models of the behavior of body structural systems rather than complex mathematical models, the book looks at the best way to shape a structural element to achieve a desired function, why structures behave in certain ways, and how to improve performance. This second edition of Fundamentals of Automobile Body Structure Design contains many new sections including: the treatment of crashworthiness conditions of static roof crush and the small overlap rigid barrier torsion stiffness requirements material selection illustrations of body architecture Each chapter now includes a clear flow down of requirements following the systems engineering methodology. Illustrations have been updated and expanded and a fresh modern format has been adapted enhancing the readability of the book.

The endothelins (ETs) are a family of related peptides of which ET-1 is the most powerful endogenous vasoconstrictor and the predominant isoform in the cardiovascular and renal systems. The ET system has been widely implicated in both cardiovascular disease and chronic kidney disease (CKD). ET-1 contributes to the pathogenesis and maintenance of hypertension and arterial stiffness, as well endothelial dysfunction and atherosclerosis. By reversal of these effects, ET antagonists, particularly those that block ETA receptors, may reduce cardiovascular risk. In CKD patients, antagonism of the ET system may be of benefit in improving renal haemodynamics and reducing proteinuria, effects seen both in animal models and in some human studies. Data suggest a synergistic role for ET receptor antagonists with angiotensin-converting enzyme inhibitors in lowering blood pressure, reducing proteinuria, and in animal models in slowing CKD progression. However, in clinical trials, fluid retention or cardiac failure has caused concern and these agents are not yet ready for general use for risk reduction in CKD.

Axial spondyloarthritis (axSpA) is a heterogeneous condition with multiple effects and a variable course. Monitoring outcomes is required to optimize treatment and care. There are a significant number of outcomes that could potentially be measured in patients with axSpA. Performing these in routine clinical practice has resource and logistic implications, so clinicians and teams looking after patients with axSpA need to decide which aspects they will monitor locally. Most national and international guidelines for the use of biologics require regular monitoring of disease activity. In this chapter, we outline suggested core data sets and review some of the key validated outcomes for axSpA. These include a range of patient-reported and clinician-assessed measures covering disease activity, symptoms (such as pain, stiffness, and fatigue), function, mobility, work disability, and quality of life. We also review the roles of acute phase blood tests and imaging in monitoring axSpA.

Bones are multifunctional passive organs of movement that supports soft tissue and directly attached muscles. They also protect internal organs and are a reserve of calcium, phosphorus and magnesium. Each bone is covered with periosteum, and the adjacent bone surfaces are covered by articular cartilage. Histologically, the bone is an organ composed of many different tissues. The main component is bone tissue (cortical and spongy) composed of a set of bone cells and intercellular substance (mineral and organic), it also contains fat, hematopoietic (bone marrow) and cartilaginous tissue. Bones are a tissue that even in adult life retains the ability to change shape and structure depending on changes in their mechanical and hormonal environment, as well as self-renewal and repair capabilities. This process is called bone turnover. The basic processes of bone turnover are: • bone modeling (incessantly changes in bone shape during individual growth) following resorption and tissue formation at various locations (e.g. bone marrow formation) to increase mass and skeletal morphology. This process occurs in the bones of growing individuals and stops after reaching puberty • bone remodeling (processes involve in maintaining bone tissue by resorbing and replacing old bone tissue with new tissue in the same place, e.g. repairing micro fractures). It is a process involving the removal and internal remodeling of existing bone and is responsible for maintaining tissue mass and architecture of mature bones. Bone turnover is regulated by two types of transformation: • osteoclastogenesis, i.e. formation of cells responsible for bone resorption • osteoblastogenesis, i.e. formation of cells responsible for bone formation (bone matrix synthesis and mineralization) Bone maturity can be defined as the completion of basic structural development and mineralization leading to maximum mass and optimal mechanical strength. The highest rate of increase in pig bone mass is observed in the first twelve weeks after birth. This period of growth is considered crucial for optimizing the growth of the skeleton of pigs, because the degree of bone mineralization in later life stages (adulthood) depends largely on the amount of bone minerals accumulated in the early stages of their growth. The development of the technique allows to determine the condition of the skeletal system (or individual bones) in living animals by methods used in human medicine, or after their slaughter. For in vivo determination of bone properties, Abstract 10 double energy X-ray absorptiometry or computed tomography scanning techniques are used. Both methods allow the quantification of mineral content and bone mineral density. The most important property from a practical point of view is the bone’s bending strength, which is directly determined by the maximum bending force. The most important factors affecting bone strength are: • age (growth period), • gender and the associated hormonal balance, • genotype and modification of genes responsible for bone growth • chemical composition of the body (protein and fat content, and the proportion between these components), • physical activity and related bone load, • nutritional factors: – protein intake influencing synthesis of organic matrix of bone, – content of minerals in the feed (CA, P, Zn, Ca/P, Mg, Mn, Na, Cl, K, Cu ratio) influencing synthesis of the inorganic matrix of bone, – mineral/protein ratio in the diet (Ca/protein, P/protein, Zn/protein) – feed energy concentration, – energy source (content of saturated fatty acids - SFA, content of polyun saturated fatty acids - PUFA, in particular ALA, EPA, DPA, DHA), – feed additives, in particular: enzymes (e.g. phytase releasing of minerals bounded in phytin complexes), probiotics and prebiotics (e.g. inulin improving the function of the digestive tract by increasing absorption of nutrients), – vitamin content that regulate metabolism and biochemical changes occurring in bone tissue (e.g. vitamin D3, B6, C and K). This study was based on the results of research experiments from available literature, and studies on growing pigs carried out at the Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences. The tests were performed in total on 300 pigs of Duroc, Pietrain, Puławska breeds, line 990 and hybrids (Great White × Duroc, Great White × Landrace), PIC pigs, slaughtered at different body weight during the growth period from 15 to 130 kg. Bones for biomechanical tests were collected after slaughter from each pig. Their length, mass and volume were determined. Based on these measurements, the specific weight (density, g/cm3) was calculated. Then each bone was cut in the middle of the shaft and the outer and inner diameters were measured both horizontally and vertically. Based on these measurements, the following indicators were calculated: • cortical thickness, • cortical surface, • cortical index. Abstract 11 Bone strength was tested by a three-point bending test. The obtained data enabled the determination of: • bending force (the magnitude of the maximum force at which disintegration and disruption of bone structure occurs), • strength (the amount of maximum force needed to break/crack of bone), • stiffness (quotient of the force acting on the bone and the amount of displacement occurring under the influence of this force). Investigation of changes in physical and biomechanical features of bones during growth was performed on pigs of the synthetic 990 line growing from 15 to 130 kg body weight. The animals were slaughtered successively at a body weight of 15, 30, 40, 50, 70, 90, 110 and 130 kg. After slaughter, the following bones were separated from the right half-carcass: humerus, 3rd and 4th metatarsal bone, femur, tibia and fibula as well as 3rd and 4th metatarsal bone. The features of bones were determined using methods described in the methodology. Describing bone growth with the Gompertz equation, it was found that the earliest slowdown of bone growth curve was observed for metacarpal and metatarsal bones. This means that these bones matured the most quickly. The established data also indicate that the rib is the slowest maturing bone. The femur, humerus, tibia and fibula were between the values of these features for the metatarsal, metacarpal and rib bones. The rate of increase in bone mass and length differed significantly between the examined bones, but in all cases it was lower (coefficient b <1) than the growth rate of the whole body of the animal. The fastest growth rate was estimated for the rib mass (coefficient b = 0.93). Among the long bones, the humerus (coefficient b = 0.81) was characterized by the fastest rate of weight gain, however femur the smallest (coefficient b = 0.71). The lowest rate of bone mass increase was observed in the foot bones, with the metacarpal bones having a slightly higher value of coefficient b than the metatarsal bones (0.67 vs 0.62). The third bone had a lower growth rate than the fourth bone, regardless of whether they were metatarsal or metacarpal. The value of the bending force increased as the animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. The rate of change in the value of this indicator increased at a similar rate as the body weight changes of the animals in the case of the fibula and the fourth metacarpal bone (b value = 0.98), and more slowly in the case of the metatarsal bone, the third metacarpal bone, and the tibia bone (values of the b ratio 0.81–0.85), and the slowest femur, humerus and rib (value of b = 0.60–0.66). Bone stiffness increased as animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. Abstract 12 The rate of change in the value of this indicator changed at a faster rate than the increase in weight of pigs in the case of metacarpal and metatarsal bones (coefficient b = 1.01–1.22), slightly slower in the case of fibula (coefficient b = 0.92), definitely slower in the case of the tibia (b = 0.73), ribs (b = 0.66), femur (b = 0.59) and humerus (b = 0.50). Bone strength increased as animals grew. Regardless of the growth point tested, bone strength was as follows femur > tibia > humerus > 4 metacarpal> 3 metacarpal> 3 metatarsal > 4 metatarsal > rib> fibula. The rate of increase in strength of all examined bones was greater than the rate of weight gain of pigs (value of the coefficient b = 2.04–3.26). As the animals grew, the bone density increased. However, the growth rate of this indicator for the majority of bones was slower than the rate of weight gain (the value of the coefficient b ranged from 0.37 – humerus to 0.84 – fibula). The exception was the rib, whose density increased at a similar pace increasing the body weight of animals (value of the coefficient b = 0.97). The study on the influence of the breed and the feeding intensity on bone characteristics (physical and biomechanical) was performed on pigs of the breeds Duroc, Pietrain, and synthetic 990 during a growth period of 15 to 70 kg body weight. Animals were fed ad libitum or dosed system. After slaughter at a body weight of 70 kg, three bones were taken from the right half-carcass: femur, three metatarsal, and three metacarpal and subjected to the determinations described in the methodology. The weight of bones of animals fed aa libitum was significantly lower than in pigs fed restrictively All bones of Duroc breed were significantly heavier and longer than Pietrain and 990 pig bones. The average values of bending force for the examined bones took the following order: III metatarsal bone (63.5 kg) <III metacarpal bone (77.9 kg) <femur (271.5 kg). The feeding system and breed of pigs had no significant effect on the value of this indicator. The average values of the bones strength took the following order: III metatarsal bone (92.6 kg) <III metacarpal (107.2 kg) <femur (353.1 kg). Feeding intensity and breed of animals had no significant effect on the value of this feature of the bones tested. The average bone density took the following order: femur (1.23 g/cm3) <III metatarsal bone (1.26 g/cm3) <III metacarpal bone (1.34 g / cm3). The density of bones of animals fed aa libitum was higher (P<0.01) than in animals fed with a dosing system. The density of examined bones within the breeds took the following order: Pietrain race> line 990> Duroc race. The differences between the “extreme” breeds were: 7.2% (III metatarsal bone), 8.3% (III metacarpal bone), 8.4% (femur). Abstract 13 The average bone stiffness took the following order: III metatarsal bone (35.1 kg/mm) <III metacarpus (41.5 kg/mm) <femur (60.5 kg/mm). This indicator did not differ between the groups of pigs fed at different intensity, except for the metacarpal bone, which was more stiffer in pigs fed aa libitum (P<0.05). The femur of animals fed ad libitum showed a tendency (P<0.09) to be more stiffer and a force of 4.5 kg required for its displacement by 1 mm. Breed differences in stiffness were found for the femur (P <0.05) and III metacarpal bone (P <0.05). For femur, the highest value of this indicator was found in Pietrain pigs (64.5 kg/mm), lower in pigs of 990 line (61.6 kg/mm) and the lowest in Duroc pigs (55.3 kg/mm). In turn, the 3rd metacarpal bone of Duroc and Pietrain pigs had similar stiffness (39.0 and 40.0 kg/mm respectively) and was smaller than that of line 990 pigs (45.4 kg/mm). The thickness of the cortical bone layer took the following order: III metatarsal bone (2.25 mm) <III metacarpal bone (2.41 mm) <femur (5.12 mm). The feeding system did not affect this indicator. Breed differences (P <0.05) for this trait were found only for the femur bone: Duroc (5.42 mm)> line 990 (5.13 mm)> Pietrain (4.81 mm). The cross sectional area of the examined bones was arranged in the following order: III metatarsal bone (84 mm2) <III metacarpal bone (90 mm2) <femur (286 mm2). The feeding system had no effect on the value of this bone trait, with the exception of the femur, which in animals fed the dosing system was 4.7% higher (P<0.05) than in pigs fed ad libitum. Breed differences (P<0.01) in the coross sectional area were found only in femur and III metatarsal bone. The value of this indicator was the highest in Duroc pigs, lower in 990 animals and the lowest in Pietrain pigs. The cortical index of individual bones was in the following order: III metatarsal bone (31.86) <III metacarpal bone (33.86) <femur (44.75). However, its value did not significantly depend on the intensity of feeding or the breed of pigs.

This chapter reviews advances in pathogenesis; European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria with clinical, laboratory, and ultrasound criteria for classification as polymyalgia rheumatica (PMR); the heterogeneity and overlap between PMR, inflammatory arthritis, and large-vessel vasculitis as illustrated by representative cases; recent guidelines on early and correct recognition, investigations, and management of PMR; the scope of disease-modifying agents; socio-economic impact, outcomes, and patient experience in PMR. It also discusses areas for future research including clinical trials with biological agents and newer steroid formulations, standardized outcome assessments, and the search for better biomarkers in PMR. PMR is one of the common inflammatory rheumatic diseases of older people and represents a frequent indication for long-term glucocorticoid (GC) therapy. It is characterized by abrupt-onset pain and stiffness of the shoulder and pelvic girdle muscles. Its management is subject to wide variations of clinical practice and it is managed in primary or secondary care by general practitioners (GPs), rheumatologists, and non-rheumatologists. The evaluation of PMR can be challenging, as many clinical and laboratory features may also be present in other conditions, including other rheumatological diseases, infection, and neoplasia. PMR is usually diagnosed in the primary care setting, but standard clinical investigations and referral pathways for suspected PMR are unclear. The response to standardized therapy is heterogeneous, and a significant proportion of patients do not respond completely. There is also an overlap with inflammatory arthritis and large-vessel vasculitis for which adjuvant disease-modifying medications are often used. Prolonged corticosteroid therapy is associated with a variety of side effects, especially when high-dose glucocorticoid therapy is employed. Giant cell arteritis (GCA) is also often linked to PMR. It is a vasculitis of large- and medium-sized vessels causing critical ischaemia. GCA is a medical emergency because of the high incidence of neuro-ophthalmic complications. Both conditions are associated with a systemic inflammatory response and constitutional symptoms. The pathogenesis is unclear. The initiating step may be the recognition of an infectious agent by aberrantly activated dendritic cells. The key cell types involved are CD4+ T cells and macrophages giving rise to key cytokines such as interferon-γ‎ (implicated in granuloma formation), PDGF (intimal hyperplasia), and interleukin (IL)-6 (key to the systemic response). The pathogenesis of PMR may be similar to that of GCA, although PMR exhibits less clinical vascular involvement. The mainstay of therapy is corticosteroids, and disease-modifying therapy is currently indicated in relapsing disease.