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Query: UMLS:C0026837 (muscle rigidity)
 1,077 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The polymeric split Hopkinson pressure bar (PSHPB) apparatus is introduced as a means for measuring the high strain rate (1,000-2,500 s(-1)) compressive properties of soft tissues. Issues related to specimen design are discussed, and protocols are presented for specimen preparation. Proposed specimen geometries were validated using high-speed photography. Stress-strain data were obtained for high strain rate compression of bovine muscle tissue to strains as high as 80%. The stress-strain curves were found to be strain rate-sensitive and concave upward, as is typical of soft tissues. Rigor had a significant impact on the material properties between 5 and 24 h post mortem, while at longer times, properties returned essentially to their pre-rigor values. This study presents some of the first published high rate properties of muscle tissue, data that are urgently for advanced modeling of the human body and for evaluation of safety systems for the human body.
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PMID:High strain rate compressive properties of bovine muscle tissue determined using a split Hopkinson bar apparatus. 1605 33

Many countries have centralized the clinical and economic assessments necessary for evidence-based drug coverage policy. We analyze such processes in Australia, Canada, New Zealand, and the United Kingdom. These countries apply comparable approaches to the assessment and appraisal of evidence but apply the processes to different types of drugs and use the reviews within different decision-making contexts. Review processes applied to all medicines and clearly tied to coverage decisions appear to influence national drug use. Rigor of process and transparency of data and rationale are believed to be important for maximizing the impact and political acceptability of the processes.
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PMID:Centralized drug review processes in Australia, Canada, New Zealand, and the United kingdom. 1683 5

Rigor has important ramifications for the entire qualitative research process. The aim of this study was to evaluate aspects of methodological congruence by focusing on four dimensions of rigor in qualitative nursing research related to the presence of patients' family members in the intensive care unit. Eight research papers covering the years 1990-2004 were analyzed by means of one of Burns and Grove's standards, methodological congruence, for critique and consistency. The results show that there are varying degrees of focus on procedural rigor, such as limitations and bias. Ethical rigor is described clearly in some papers, while others lack descriptions of confidentiality and the voluntary nature of participation. However, all papers contain descriptions of qualitative data analysis. In conclusion, there were strengths in procedural rigor and auditability, but also some limitations in the identification of theoretical development and the scientific tradition on which the article is based.
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PMID:Methodological aspects of rigor in qualitative nursing research on families involved in intensive care units: a literature review. 1730 May 47

Dying in a head-down position is rare, and autopsy may reveal no morphological findings which can sufficiently explain the cause of death. The authors describe a case of positional asphyxia of a 78-year-old man, found dead hanging in head-down position inside a blackberry bush. The subject was suspended by his left leg and wedged inside a thick blackberry bush, while his right leg was free and inflected. Investigation revealed that the elderly man had last been seen after lunch in the early afternoon (about 2.00 p.m.), two days before being found. The subject had no pre-existing physical or mental condition which might have explained his death. He was 164 cm tall and weighed 90 kg (BMI: 33.4). External examination of the body revealed abrasions on the head and multiple superficial scratch marks on the hands; no external signs of violence were observed. The deceased's head was cyanotic and revealed marked petechial haemorrhages of the conjunctiva. Rigor mortis was fully developed and reddish fixed livor was observed on the face, neck and upper chest. The distribution of livor was consistent with the position of the body at the scene. Autopsy revealed marked pulmonary and cerebral oedema; the liver showed fatty vacuolization with a mild increase of connective tissue and thickening of the walls of the central veins and centrilobular sinusoids. The heart was enlarged, particularly the left ventricle, with a slight, calcified, diffuse and increased thickness of the aortic and coronary arteries. The remains of meat and vegetables in the initial phase of digestion were found inside the stomach, and there was a strong smell of alcohol. The blood alcohol concentration, ascertained by GC (Gas Chromatography), was 2.10 g/l. Toxicological assays for addictive drugs (cocaine, heroin, THC) yielded negative results. There were no features suggesting that the deceased had been the victim of an assault. The authors of this case report illustrate the main pathophysiological and diagnostic features of positional asphyxia and possible relevant co-causes of death, with an emphasis on the combined role of acute alcoholic intoxication and obesity in the hastened demise of a subject in the head-down position.
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PMID:Death in head-down position in a heavily intoxicated obese man. 1824 60

Discoveries, understanding, and innovations in meat science during the last century have led to revolutionary changes in meat and poultry production, processing, marketing, and consumption. American Society of Animal Science members have made key contributions in most, if not all, categories of advancement. The first US university meat science program was begun in Minnesota in 1905. Use of mechanical refrigeration in the meatpacking industry, improved transportation and packaging, and home refrigeration provided more flexibility, variety, and consistency in meat and meat products in the early 1900s. Cooperative meat research was begun by 27 universities in 1925, with a focus on the observational characterization of carcass traits and composition, meat quality attributes, and causes of the wide variation in these variables. Scientific study of genetic, nutritional, and environmental influences on the growth, physiology, and postmortem biochemistry of muscle often used muscle-comparative investigations. Rigor mortis, cold shortening and thaw rigor, postmortem muscle metabolism, postmortem tenderization and tenderness variation, and postmortem myoglobin and lipid oxidation were studied vigorously in the 1960s and beyond, defining the biochemical bases for associated outcomes in fresh and processed products. Value-added benefits resulted from implementation of electrical stimulation, boxed beef and modified-atmosphere packaging, restructuring technologies, collagen recovery, and muscle profiling work. Isolation, purification, and definition of the primary structure and biophysical properties of the myofribillar and cytoskeletal proteins in muscle aided the understanding of contraction and postmortem changes. The role of Ca-dependent proteases in meat tenderness and muscle growth is being clarified. The chemistry of meat curing, meat emulsion formation, fermentation, and other processing methods led to new technologies, new meat products, and new benchmarks in product shelf life and quality. Meat safety assurance and our ability to manage the microbiological causes of food-borne illness and spoilage are imminently important now and in the future.
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PMID:ASAS Centennial paper: a century of pioneers and progress in meat science in the United States leads to new frontiers. 1906 48

Ischemic preconditioning has a powerful protective potential against a reperfusion-induced injury of the post-ischemic myocardium. Cardiomyocyte hypercontracture, i.e. excessive cell shortening, is an essential mechanism of the reperfusion-induced injury. Rigor contracture, i.e. Ca(2+)-independent contracture, has been shown to be an import component of the reperfusion-induced hypercontracture. Since rigor contracture is dependent on the rapidity of the metabolic recovery during reoxygenation, we hypothesized that preconditioning of the cardiomyocyte mitochondria may improve mitochondrial function to restore the energy balance during the initial phase of reoxygenation and may thus prevent rigor contracture. For this purpose adult rat cardiomyocytes were exposed to anoxia with subsequent reoxygenation. For preconditioning, cells were pre-treated with the mitochondrial ATP-sensitive K(+) channel opener diazoxide. Pre-treatment with 100 micromol/l diazoxide significantly reduced the reoxygenation-induced hypercontracture of cardiomyocytes due to an attenuation of the Ca(2+)-independent rigor-type contracture, which was accompanied by an acceleration of the phosphocreatine resynthesis during the initial phase of reoxygenation. Treatment with the mitochondrial ATP-sensitive K(+) channel antagonist 5-hydroxydecanoate (500 micromol/l) during preconditioning phase abolished these protective effects. Similarly, partial suppression of the mitochondrial function with 100 micromol/l NaCN during the reoxygenation phase abolished the diazoxide effects. Finally, in isolated rat hearts, preconditioning with diazoxide prior to global ischemia significantly improved left ventricular function and attenuated hypercontracture during reperfusion. This effect could be abolished by the treatment with 100 micromol/l NaCN during reperfusion. Taken together, pharmacological preconditioning of cardiomyocytes with diazoxide protects against the reoxygenation-induced rigor hypercontracture due to an improvement of the energy recovery at the onset of reoxygenation.
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PMID:Preconditioning with diazoxide prevents reoxygenation-induced rigor-type hypercontracture. 1940 25

Good alpha taxonomy is central to biology. On the basis of a survey of arthropod studies that used multiple disciplines for species delimitation, we evaluated the performance of single disciplines. All included disciplines had a considerable failure rate. Rigor in species delimitation can thus be increased when several disciplines chosen for complementarity are used. We present a flexible procedure and stopping rule for integrative taxonomy that uses the information from different disciplines separately. Disagreement among disciplines over the number and demarcation of species is resolved by elucidating and invoking evolutionary explanations for disagreement. With the identification of further promising study organisms and of new questions for in-depth analysis, evolutionary biology should profit from integrative taxonomy. An important rationale is clarity in researcher bias in the decision-making process. The success of integrative taxonomy will further increase through methodological progress, taxonomic training of evolutionary biologists, and balanced resource allocation.
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PMID:Integrative taxonomy: a multisource approach to exploring biodiversity. 1973 81

1. X-ray diffraction studies of sartorius muscles of Rana pipiens were made in a new x-ray diffraction camera which permits exposures of 3 to 6 minutes. The object-film distance can be varied from 20 to 80 mm; the muscle inside the camera can be electrically stimulated while contracting isotonically or isometrically, and can be observed by a special device. After exposures up to 30 minutes (approximately 40,830 r) muscles are still alive and responsive. 2. Contrary to the x-ray diffraction pattern of powdered dry muscle, which pattern consists of two rings corresponding to spacings of 4.46 A.u. and 9.66 A.u., both moist and dried whole sartorius muscle show signs of orientation in both rings, consisting of two equatorial streaks (wet) or points (dry) and meridional sickles. The moist muscle shows in addition a diffuse water ring. The spacings corresponding to the orientation points and elliptical structure show only slight differences in moist and dried samples. Through statistical computations based on two different series consisting of thirteen moist and twenty-eight dried samples, and nine muscles before and after drying, it was shown that only the divergence in the smaller spacing has some real significance, which indicates that most water of the moist muscle is bound intermolecularly. Upon resoaking of dried muscle the x-ray diffraction pattern of the moist muscle is restored. 3. Stretching of muscle by weights below the breaking point produces an additional well defined diffraction line, corresponding to a spacing of 4.32 A.u. A similar diffraction line can be produced in frog tendon upon stretching. 4. The influence of heat on the x-ray diffraction pattern of muscle depends upon the maximum temperature and the length of action; 5 minutes at 50 degrees C. markedly reduces the orientation of the sample; 5 minutes' immersion in boiling Ringer's solution destroys the orientation and produces a ring corresponding to a spacing of 5.3 to 5.5 A.u. in the moist and sharpening of the backbone reflection in the dried specimen. 5. Ultraviolet light brings forth changes in the x-ray diffraction pattern varying with the intensity of the irradiation. Ultimately a disappearance of the equatorial points and of the outside sickles is achieved while the elliptical shape of the outside ring and its diffuseness persist. In addition two salt rings characteristic of NaCl indicate that the irradiated muscles have become permeable to the surrounding medium (Ringer's solution). 6. Both faradic and single shock electrical stimulation were tried on muscles. If shortening of the muscle is prevented either by sufficient weight or by tying the muscle in a frame, no changes in the x-ray diffraction pattern occur; if the muscle is allowed to shorten without weights or by using insufficient weights, then the orientation either disappears completely or partially. When the muscle is stretched while contracted by electrical stimulation the orientation of the x-ray diffraction pattern reappears. 7. A number of salts with uni- and bivalent ions in concentrations corresponding osmotically to 0.73 per cent NaCl and 10 per cent NH(4)Cl were studied in their effects upon the x-ray diffraction of muscles. Of the salts with univalent ions in the lower concentration only KCl causes a marked decrease of orientation and an increase in the permeability of the fiber membranes. Similar effects on the orientation seem to be produced by CaCl(2) while MgCl(2) causes rather a more pronounced orientation. At hypertonic salt concentrations the orientation disappears completely and the corresponding salt rings become visible. Besides, NaCNS seems to have a specific effect on the outside ring and LiCl produces a ring at 21.3 A.u. and a splitting of the outside ring. 8. Strong mineral and lactic acids in concentrations up to 0.005 N have little if any influence upon the x-ray diffraction of muscles. A further increase in acidity to 0.01 N and above destroys the orientation completely, causes sharpening of the backbone reflection, and increased membrane permeability. These changes are irreversible upon neutralization. Also the effects of swelling upon the water ring of fresh muscle become manifest. Weak acids at higher concentrations show an effect similar to that of strong acids. 9. Rigor mortis produces a more or less complete loss of orientation. The muscles show signs of increased permeability. 10. Alkalies destroy the orientation of the x-ray diffraction pattern. The effective concentration is higher than the corresponding amount of acid. 11. Formaldehyde produces only minor changes in the x-ray diffraction patterns of muscles. 12. The effects of alcohol depend primarily upon the concentration applied. Low concentrations (5 per cent) seem to have a passing stimulating effect, at concentrations of 15 per cent, the anesthetizing effect becomes manifest in well defined orientation. The diameter of the water ring is reduced. If 95 per cent alcohol is allowed to act upon muscle for more than 12 minutes, then the orientation disappears completely and the backbone spacing becomes as sharp as in boiled muscle. 13. The effects of chloroform depend upon whether the muscle is allowed to contract or not. Only if the muscle is allowed to contract in chloroform-saturated Ringer's solution is the orientation lost and salt rings appear as well as a ring corresponding to a spacing of 22 A.u,, which has been observed in other changes in muscles. 14. In muscles allowed to shorten in a caffeine-Ringer's solution the orientation disappears, salt rings become visible as well as a decrease in size of the water ring; a new arc corresponding to a spacing of 4.18 A.u. was observed in one case.
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PMID:X-RAY DIFFRACTION STUDIES ON FROG MUSCLES. 1987 11

Rigor mortis is conventionally a postmortem change. Its occurrence suggests that death has occurred at least a few hours ago. The authors report a case of "Rigor Mortis" in a live patient after cardiac surgery. The likely factors that may have predisposed such premortem muscle stiffening in the reported patient are, intense low cardiac output status, use of unusually high dose of inotropic and vasopressor agents and likely sepsis. Such an event may be of importance while determining the time of death in individuals such as described in the report. It may also suggest requirement of careful examination of patients with muscle stiffening prior to declaration of death. This report is being published to point out the likely controversies that might arise out of muscle stiffening, which should not always be termed rigor mortis and/ or postmortem.
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PMID:"Rigor mortis" in a live patient. 2117 Dec 4

Multidetector computed tomography (MDCT) has emerged as an effective imaging technique to augment forensic autopsy. Postmortem change and decomposition are always present at autopsy and on postmortem MDCT because they begin to occur immediately upon death. Consequently, postmortem change and decomposition on postmortem MDCT should be recognized and not mistaken for a pathologic process or injury. Livor mortis increases the attenuation of vasculature and dependent tissues on MDCT. It may also produce a hematocrit effect with fluid levels in the large caliber blood vessels and cardiac chambers from dependent layering erythrocytes. Rigor mortis and algor mortis have no specific MDCT features. In contrast, decomposition through autolysis, putrefaction, and insect and animal predation produce dramatic alterations in the appearance of the body on MDCT. Autolysis alters the attenuation of organs. The most dramatic autolytic changes on MDCT are seen in the brain where cerebral sulci and ventricles are effaced and gray-white matter differentiation is lost almost immediately after death. Putrefaction produces a pattern of gas that begins with intravascular gas and proceeds to gaseous distension of all anatomic spaces, organs, and soft tissues. Knowledge of the spectrum of postmortem change and decomposition is an important component of postmortem MDCT interpretation.
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PMID:Postmortem imaging: MDCT features of postmortem change and decomposition. 2001 Feb 92


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