Książki na temat „Muscles Genes”

Restrictive cardiomyopathy is a heart muscle disorder characterized by increased myocardial stiffness that results in an abnormally steep rise in intraventricular pressure with small increases in volume in the presence of normal or decreased diastolic left ventricular volumes and normal ventricular wall thickness. The disease may be caused by mutations in a number of genes or myocardial infiltration. Arrhythmogenic right ventricular cardiomyopathy is an inherited cardiac muscle disease associated with sudden cardiac death, ventricular arrhythmias, and cardiac failure. It is most frequently caused by mutations in desmosomal protein genes that lead to fibrofatty replacement of cardiomyocytes, right ventricular dilatation, and aneurysm formation.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a disorder of the heart muscle which is typically inherited in an autosomal dominant manner. It is believed to be familial in over 50% of cases. A recessive mode of inheritance has also been reported in syndromic cases with cardiocutaneous features. The classic form of the disorder is considered to be ‘a disease of the desmosome’ as pathogenic variants have been identified in five genes encoding key desmosomal proteins: plakoglobin, desmoplakin, plakophilin-2, desmoglein-2, and desmocollin-2. Mutations in these genes account for 30–50% of ARVC cases. A further eight non-desmosomal genes have also been implicated in the pathogenesis of the disorder but only account for rare cases. Studies of patients with ARVC-associated gene mutations have revealed marked genetic heterogeneity and very limited genotype–phenotype correlation. Disease expression often varies significantly amongst individuals carrying the same mutation. It has been proposed that the presence of more than one sequence variant is required to determine overt clinical disease and patients with multiple variants have a more severe phenotype compared to single variant carriers. Identification of a potentially pathogenic variant comprises a major criterion in the diagnosis of ARVC but informative integration of genetic testing into clinical practice remains challenging. Gene testing should be used to identify asymptomatic family members at risk and only aids diagnosis in cases of high suspicion for ARVC, along with other evident features of the disease already present. However, genetic findings should be used with caution in clinical practice and their interpretation must be performed in expert centres.

Trichinellosis is caused by nematodes of the genus Trichinella. These zoonotic parasites show a cosmopolitan distribution in all the continents, but Antarctica. They circulate in nature by synanthropic-domestic and sylvatic cycles. Today, eight species and four genotypes are recognized, all of which infect mammals, including humans, one species also infects birds, and two other species infect also reptiles.Parasites of the genus Trichinella are unusual among the other nematodes in that the worm undergoes a complete developmental cycle, from larva to adult to larva, in the body of a single host, which has a profound influence on the epidemiology of trichinellosis. When the cycle is complete, the muscles of the infected animal contain a reservoir of larvae, capable of long-term survival. Humans and other hosts become infected by ingesting muscle tissuescontaining viable larvae.The symptoms associated with trichinellosis vary with the severity of infection, i.e. the number of viable larvae ingested, and the time after infection. The capacity of the worm population to undergo massive multiplication in the body is a major determinant. Progression of disease follows the biological development of the parasite. Symptoms are associated first with the gastrointestinal tract, as the worms invade and establish in the small intestine, become more general as the body responds immunologically, and finally focus on the muscles as the larvae penetrate the muscle cells and develop there. Although Trichinella worms cause pathological changes directly by mechanical damage, most of the clinical features of trichinellosis are immunopathological in origin and can be related to the capacity of the parasite to induce allergic responses.The main source of human infection is raw or under-cooked meat products from pig, wild boar, bear, walrus, and horses, but meat products from other animals have been implicated. In humans, the diagnosis of infection is made by immunological tests or by direct examination of muscle biopsies using microscopy or by recovery of larvae after artificial digestion. Treatment requires both the use of anthelmintic drugs to kill the parasite itself and symptomatic treatment to minimize inflammatory responses.Both pre-slaughter prevention and post-slaughter control can be used to prevent Trichinella infections in animals. The first involves pig management control as well as continuous surveillance programmes. Meat inspection is a successful post-slaughter strategy. However, a continuous consumer education is of great importance in countries where meat inspection is not mandatory.

Anaerobic organisms of the genus Clostridia (C) can cause significant human disease. Exotoxins secreted by C botulinum and C tetani cause botulism and tetanus, respectively (summarized in Table 156.1). Botulinum neurotoxin causes neuromuscular blockade by interfering with vesicular acetylcholine release, leading to cholinergic blockade at the neuromuscular junctions of skeletal muscle, and consequently, symmetric flaccid paralysis. Tetanus toxin prevents release of inhibitory neurotransmitters at central synapses, leading to overactivity of motor neurons and muscle rigidity and spasms. This chapter reviews clinical features of botulism and tetanus and discusses their pathophysiological basis.

Serum creatine kinase (CK) levels may be elevated in patients with muscle weakness or pain. In asymptomatic patients with CK elevations, the focus should be on identifying reversible causes, followed by investigation for inherited muscle diseases. In asymptomatic patients with an incidental finding of elevated CK, clinicians should look for reversible causes, then re-test the CK after 10 days of rest in the absence of potential triggers. If the CK remains markedly elevated and/or electromyography proves myopathic, a muscle biopsy should be considered. Women of childbearing age with elevation of serum CK should be evaluated for dystrophin mutation. Genetic causes of hyperCKaemia can be pursued with targeted gene sequencing, or whole exome or next generation sequencing. Patients with inherited skeletal muscle diseases may also have associated cardiac disease, so a cardiology evaluation should be considered in all patients with unexplained CK elevations.

The dystonias are a large group of disorders characterized by excessive muscle activity leading to abnormal movements. They are clinically diverse, affecting different parts of the body at all ages in both humans and other animals. They also are etiologically diverse, with causes that are either inherited due to specific dystonia-causing genes, or acquired because of nervous system injury or exposure to certain drugs or chemicals. Despite the clinical and etiological heterogeneity, there is an increasing appreciation that certain subgroups of dystonias share some biological abnormalities at the molecular, cellular, anatomical, or physiological levels.

The aim of the study was to determine the effect of feed additives (algae, soybean, and sunflower oil) used in the rabbit feed on: growth indices and slaughter traits, pH, colour, texture, chemical composition, fatty acid profile and oxidative stability (TBARS) of the meat as well as FTO and FABP4 genes expression in the meat’s intramuscular fat (m. longissimus lumborum), depending on the age and sex. The experimental material consisted of Termond White rabbits (n = 160, 80 females and 80 males). Animals were weaned on the 35th day of life, and housed in metal cages arranged in batteries (4 rabbits of the same sex in a cage). From weaning to 12 or 18 weeks of age, the rabbits were fed pellets ad libitum. Animals in the control group (C) received non-supplemented pellets throughout the experiment. In the other groups, the pellet contained 1% algae (A), 3% sunflower oil (OS), and 3% soybean oil(SO).The experimental diets were formulated to have similar protein and energy content. Diets were balanced by lowering the proportion of other feed components. The total share of all components remained at 100%. The results indicate that 3% vegetable oils (soybean or sunflower) supplementation of diets for growing rabbits leads to an increase of body weight and improvement of some of the slaughter traits, while 1% addition of algae to the feed causes deterioration of body weight and slaughter traits. The effect of oil additive depends on the animals’ age. Supplementation of the rabbits’ diet with algae (1%) or sunflower and soybean oils (3%) led to an increase in the dressing percentage of rabbits slaughtered at 18 weeks of age (approx. 3%), but had no effect on the dressing percentage of rabbits slaughtered at 12 weeks of age. Feeding pellets with either 3% vegetable oils or 1% algae additive to the rabbits did not significantly change the chemical composition of the meat. Protein content increased and intramuscular fat content decreased with age, while ash and water content were similar. The feed additives significantly differentiated meat acidity without deteriorating meat quality. Diet modification has not affected negatively meat colour. 24 h after the slaughter, the colour of rabbit meat was similar across the studied feeding groups. Correlation between diet and rabbits’ age was found. Meat texture (hardness, springiness and chewiness) of all rabbit groups slaughtered at 12 weeks of age was similar, and the shear for cewas greater in rabbits fed pellets with algae and soybean oil. At 18 weeks of age, rabbit meat from experimental groups had lower hardness and chewiness, compared to meat of the animals from the control group. Meat shear force was higher in the control group, and from algae-supplemented group. The correlation between diet and age was also found. The use of 3% vegetable oils or 1% algae as feed additives significantly reduced meat oxidative stability. Soybean or sunflower oil (3%) usedas feed additives favourably modified the fatty acid composition of intramuscular fat. Polyunsaturated fatty acids (PUFA) content was increased, including linoleic acid, and PUFA/MUFA ratio was improved. The content of these acids decreased with age. The use of algae (1%) as a feed additive resulted in positive effect on the increase of n-3 fatty acid content (EPA and DHA) in meat intramuscular fat. Algae supplementation improved pro-health properties of meat, with low n-6/n-3 acid ratio (2.5), indicating that diet modification may affect the fatty acid composition of rabbit meat. The influence of diet and age on FTO and FABP4 gene expression in meat intramuscular fat (m. longissimus lumborum) was found. FTO and FABP4 gene expression increased with age and was the highest in the group of rabbits with 1% algae supplementation in the diet. The effect of rabbits’ gender on growth, slaughter traits, meat quality and gene expression in rabbits was not observed. In conclusion, the use of natural feed additives, such as sunflower, soybean oil or algae, can improve the nutritional value of rabbit meat, without changing its chemical or physical properties, and therefore the meat can serve as functional food, with properties beneficial to human health. The results obtained in this study also indicate that the expression of FTO and FABP4 genes in rabbit muscles is regulated by dietary factors and age, which, in addition to cognitive significance, has practical implications for improving technological and dietary quality of rabbit meat.

The diagnosis of Alport syndrome is suspected from the clinical features and confirmed by identifying the almost pathognomonic ultrastructural changes to the basement membrane in a family member with early disease (so that glomeruli are not too sclerosed), or in modern times by identifying a causative mutation in one or more of the three implicated COL4 genes. Genetic testing is becoming simpler and cheaper, but is still out of the reach of many. Eighty-five per cent of cases are caused by COL4A5 mutations and 10–15% by autosomal recessive disease. A significant proportion of morbidity in X-linked disease occurs in female ‘carriers’ heterozygous for the disease. Changes by light microscopy are non-specific, and can be misleading unless accompanied by electron microscopy. Immunohistology can be helpful but may not be definitive as some causative mutations are not associated with absence of protein product. As COL4A5 is expressed in skin, skin studies are theoretically useful, but they are technically challenging and only a definite negative result is helpful. It is important to distinguish other disorders causing renal disease with deafness, and other causes of glomerular haematuria. Two rare syndromes are caused by extended deletions beyond the COL4A5 gene: X-linked Alport syndrome with diffuse oesophageal leiomyomatosis in which smooth muscle leoimyomas is transmitted in a dominant fashion, and X-linked Alport syndrome with mental retardation.

Regular physical activity and fitness are key contributors to children’s health. It is important to understand sources of variation in phenotypes seen among children and adolescents. It is important to calculate the relative importance of genetic and environmental factors to observed individual differences. Heritability estimates of physical activity vary, depending on sample size and measurement instrument, but the overall importance of environmental factors seems to decrease in adolescence, whereas genetic effects become more prominent. Twin and family studies show that individual differences in maximal oxygen uptake, muscle strength, flexibility, and balance are affected by genetic factors. Some evidence is found for specific genes coding for physical activity and fitness, but children and adolescent studies are limited. Future research should prioritize these target groups as knowledge of the source of individual differences in physical activity and fitness at different time points can optimize the choice and timing of exercise intervention.

This chapter explains the principles of how best to use the main diagnostic tools in paediatric neurology in the context of evidence-based medicine. The description of neuroradiology includes the principles of DWI, SWI, MRS, ASL and fMRI, and the usefulness of ultrasound, CT and PET scanning; neuroradiological anatomy, terminology, common incidental findings and normal myelination patterns. An approach to white matter and developmental brain abnormalities is depicted. Neurogenetic testing discusses the capabilities and limitations of microarray for Comparative Genomic Hybridization (copy-number variants), gene panel testing, and whole exome and whole genome next generation sequencing. The chapter offers the theory, practicality and pitfalls of electroencephalography, peripheral neurophysiology and evoked potential testing. Common practical procedures are described, including lumbar puncture, muscle biopsy and shunt tapping with an understanding of the place of special investigations on CSF, blood, urine, and skin. The scope of neuropsychological testing is described.

Cystinosis is a rare autosomal recessive disease caused by mutations in the lysosomal cystine transporter cystinosin encoded by the CTNS gene (17p.13.2). Cystinosis is characterized by lysosomal cystine accumulation throughout the body with renal Fanconi syndrome being the most common presenting symptom of a multisystem disorder. It must be distinguished from cystinuria in which formation of cystine stones is the core problem. When left untreated, kidney dysfunction gradually progresses towards end-stage renal failure during the first 10 years of life. The advent of renal replacement therapy allowed cystinosis patients to survive into adulthood, but revealed numerous extrarenal manifestations of the disease, affecting eyes, endocrine organs, gastrointestinal tract, muscles, and central and peripheral nervous systems. The disease mechanism of cystinosis is not fully understood. The administration of the cystine-depleting agent cysteamine slows down renal and extrarenal organ damage, pointing to the pivotal role of cystine accumulation in the disease pathogenesis. Treatment with cysteamine should be initiated as early as possible and continued lifelong, and also after kidney transplantation for protecting extrarenal organs. Cysteamine eye drops are an indispensable part of the treatment of corneal cystine accumulation. Life expectancy of cystinosis patients has substantially improved and is now above 50 years.

Disorders of bone mineralization cause rickets in children and osteomalacia in adults. Both remain common in developing countries. Incidence in Western countries had declined since the fortification of foodstuffs, but appears to be increasing again. Calcium and inorganic phosphate are the key precursors for bone mineralization and growth. The commonest aetiology of osteomalacia is vitamin D deficiency, primarily due to low dietary intake and inadequate sun exposure. In the last decade gene mutations have been identified that are responsible for inherited rickets and osteomalacia, particularly those that result in phosphate deficiency, hypophosphatasia, and vitamin D receptor or metabolizing enzyme mutations. Additionally, the pathogenesis of tumour-induced osteomalacia is becoming better understood. Osteomalacia may present as bone pain and tenderness, muscle pain and weakness, and skeletal deformity or fracture. Key investigations include biochemical assessment and plain radiographs. Radioisotope bone scans and bone biopsy may be considered in selected cases. Differential diagnoses include osteoporosis, seronegative arthritides, and localized soft tissue disorders. Treatment, guided by the underlying aetiology, aims to reduce symptoms, fracture risk, bone deformity and sequelae. Vitamin D deficient patients require vitamin D and calcium replacement.

Disorders of bone mineralization cause rickets in children and osteomalacia in adults. Both remain common in developing countries. Incidence in Western countries had declined since the fortification of foodstuffs, but appears to be increasing again. Calcium and inorganic phosphate are the key precursors for bone mineralization and growth. The commonest aetiology of osteomalacia is vitamin D deficiency, primarily due to low dietary intake and inadequate sun exposure. In the last decade gene mutations have been identified that are responsible for inherited rickets and osteomalacia, particularly those that result in phosphate deficiency, hypophosphatasia, and vitamin D receptor or metabolizing enzyme mutations. Additionally, the pathogenesis of tumour-induced osteomalacia is becoming better understood. Osteomalacia may present as bone pain and tenderness, muscle pain and weakness, and skeletal deformity or fracture. Key investigations include biochemical assessment and plain radiographs. Radioisotope bone scans and bone biopsy may be considered in selected cases. Differential diagnoses include osteoporosis, seronegative arthritides, and localized soft tissue disorders. Treatment, guided by the underlying aetiology, aims to reduce symptoms, fracture risk, bone deformity and sequelae. Vitamin D deficient patients require vitamin D and calcium replacement.

Hypermobility-related syndromes constitute a family of heritable disorders of connective tissue (HDCT) that derive from abnormalities affecting genes that encode for the connective tissue matrix proteins such as collagen, fibrillin, and tenascin. They range from such commonplace though poorly recognized conditions such as the joint hypermobility syndrome (JHS) to the better-known, if more rare, eponymous syndromes such as Marfan's syndrome (MFS) and the different types of the Ehlers-Danlos syndrome (EDS). The more common presentations are with skin pathology (bruising, scaring), joint or spinal and/or muscle pain and instability with vulnerability to injury and chronic widespread pain, cardiac valve pathologies, and in MFS and vascular EDS, arterial dilatation with the risk of dissection and rupture. JHS (widely considered synonymous with the EDS hypermobility type) is further complicated by cardiovascular autonomic dysfunction such as orthostatic intolerance, palpitations, and syncope, and the recently described and commonly encountered pangastrointestinal dysmotility. The latter can manifest as gastro-oesophageal reflux, gastroparesis, slow-transit constipation, or rectal evacuatory dysfunction with rectal intussusception. In addition, HDCT are associated with bladder and uterine problems as a consequence of pelvic floor weakness. Such multisystemic conditions need to be managed by a multidisciplinary team able to draw on medical, surgical, physical, and psychological interventions by appropriately experienced specialists and therapists. This chapter introduces the reader to the epidemiology, genetics, classification, and clinical presentation of JHS, EDS, and MFS. It also describes the key investigations required to support a diagnosis and assess complications of an HDCT, as well as the multidisciplinary approach to management.

Abstract: This book describes how bioprinting emerged from 3D printing and details the accomplishments and challenges in bioprinting tissues of cartilage, skin, bone, muscle, neuromuscular junctions, liver, heart, lung, and kidney. It explains how scientists are attempting to provide these bioprinted tissues with a blood supply and the ability to carry nerve signals so that the tissues might be used for transplantation into persons with diseased or damaged organs. The book presents all the common terms in the bioprinting field and clarifies their meaning using plain language. Readers will learn about bioink—a bioprinting material containing living cells and supportive biomaterials. In addition, readers will become at ease with concepts such as fugitive inks (sacrificial inks used to make channels for blood flow), extracellular matrices (the biological environment surrounding cells), decellularization (the process of isolating cells from their native environment), hydrogels (water-based substances that can substitute for the extracellular matrix), rheology (the flow properties of a bioink), and bioreactors (containers to provide the environment cells need to thrive and multiply). Further vocabulary that will become familiar includes diffusion (passive movement of oxygen and nutrients from regions of high concentration to regions of low concentration), stem cells (cells with the potential to develop into different bodily cell types), progenitor cells (early descendants of stem cells), gene expression (the process by which proteins develop from instructions in our DNA), and growth factors (substances—often proteins—that stimulate cell growth, proliferation, and differentiation). The book contains an extensive glossary for quick reference.

Malignant hypertension (MH) is recognized clinically by elevated blood pressure together with retinal haemorrhages or exudates with or without papilloedema (grades III or IV hypertensive retinopathy); and may constitute a hypertensive emergency or crisis when complicated by evidence of end-organ damage including microangiopathic haemolysis, encephalopathy, left ventricular failure, and renal failure. Though reversible, it remains a significant cause of end-stage renal failure, and of cardiovascular and cerebrovascular morbidity and mortality in developing countries.MH can complicate pre-existing hypertension arising from diverse aetiologies, but most commonly develops from essential hypertension. The absolute level of blood pressure appears not to be critical to the development of MH, but the rate of rise of blood pressure may well be relevant in the pathogenesis. The pathogenesis of this transformation remains unclear.The pathological hallmark of MH is the presence of fibrinoid necrosis (medial vascular smooth muscle cell necrosis and fibrin deposition within the intima) involving the resistance arterioles in many organs. Fibrinoid necrosis is not specific to MH and this appearance is seen in other conditions causing a thrombotic microangiopathy such as haemolytic uraemic syndrome, scleroderma renal crisis, antiphospholipid syndrome, and acute vascular rejection post transplant. MH can both cause a thrombotic microangiopathy (TMA) but can also complicate underlying conditions associated with TMA.The pathophysiological factors that interact to generate and sustain this condition remain poorly understood. Risk factors include Afro-Caribbean race, smoking history, younger age of onset of hypertension, previous pregnancy, and untreated hypertension associated with non-compliance or cessation of antihypertensive therapy.Evidence from clinical studies and animal models point to a central role for the intrarenal renin–angiotensin system (RAS) in MH; there is good evidence for renal vasoconstriction and activation of the renal paracrine RAS potentiating MH once established; however, there may also be a role in the predisposition of MH suggested by presence of increased risk conferred by an ACE gene polymorphism in humans and polymorphisms for both ACE and AT1 receptor in an animal model of spontaneous MH. Other vasoactive mediators such as the endothelin and the inflammatory response may be important contributing to and increasing endothelial damage. There have been no randomized controlled trials to define the best treatment approach, but progressive lowering of pressures over days is considered safest unless made more urgent by critical clinical state. It seems logical to introduce ACE inhibition cautiously and early, but in view of the risk of rapid pressure lowering some recommend delay.

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.