Days Of Casting Research Articles

Nuclear Fragmentation and Ultrastructural Changes in Skeletal Muscle after Immobilisation

Linda Maxwell, H Smith University of Auckland, New Zealand Nuclear DNA fragmentation and ultrastructural changes, indicative of myonuclear apoptosis, were examined in adult skeletal muscle in response to short-term immobilisation. Adult rabbits were allocated to two (n = 5) or six (n = 5), days of unilateral casting of the ankle in full plantarflexion, or were used as untreated controls (n = 2). Atrophy of the soleus muscle was apparent by significant reductions in wet mass of 15% and 26% after two and six days of casting (p ≤ 0.05) respectively. Mean fibre cross-sectional area and myonuclear number per section were also lower (17% and 9.1% respectively) after six days of casting, in comparison to contralateral control muscles (p ≤ 0.05). Electron microscopic examination showed condensed chromatin and irregularly shaped myonuclei and capillary endothelial cell nuclei in muscles immobilised for either two or six days. Myofibrillar disruption, and abnormalities of the subsarcolemmal mitochondria were also apparent in casted muscles in the absence of inflammation or plasma membrane alterations. Longitudinal and transverse sections showed abundant in-situ end-labelling of DNA strand breaks (TUNEL) after two days, with less after six days, of immobilisation. Positive labelling corresponded to myonuclear locations within fibres, yet additional TUNEL-positive nuclei indicated DNA fragmentation in capillary endothelial cells and fibroblasts. The data indicate that the immobilisation of slow--twitch skeletal muscle in a shortened position rapidly induces morphological alterations consistent with mitochondrial dysfunction and apoptotic myonuclear elimination. Physiotherapy and Parkinson’s Disease: Evaluating best practice

DNA END-LABELLING AND MORPHOLOGICAL CHANGES IN SKELETAL MUSCLE AFTER SHORT-TERM IMMOBILIZATION

200 A reduced contractile activity of skeletal muscle induces cellular atrophy and tissue remodelling. It was the objective of this study to examine the nature of the myonuclear loss associated with fibre atrophy, and other morphological changes, induced by short-term immobilization of skeletal muscle. Adult rabbits were allocated to 2 (n = 5), or 6 (n = 5), days of unilateral cast immobilization of the ankle in full plantar flexion, or were used as untreated controls (n = 2). Soleus muscle sections were examined by light microscopy and image analysis following in situ enzyme-mediated end-labelling of nuclear DNA strand breaks (TUNEL), and by transmission electron microscopy. Muscle mass and fibre cross-sectional areas were reduced by 12% and 14%, respectively, after 2 days, and by 26% and 29%, respectively, after 6 days of immobilization, in comparison to non-casted soleii (all p < 0.05). Myonuclear numbers per transverse section were significantly lower after 6 days of casting. Nuclei-to-cross-sectional area ratios did not differ between casted and control muscles. Longitudinal, and transverse, sections showed abundant TUNEL after 2 days, with less after 6 days, of immobilization. Positive labelling corresponded to myonuclear locations within fibres, yet additional TUNEL-positive nuclei indicated DNA fragmentation in endothelial cells, fibroblasts, and/or inflammatory cells. Electron microscopic examination showed condensed chromatin and irregular shape, predominantly in capillary endothelial nuclei, and, less frequently, in myonuclei, of muscles immobilized for either 2 or 6 days. The immobilization of slow-twitch skeletal muscle in a shortened position rapidly induces morphological alterations indicative of endothelial cell and myonuclear apoptosis. Funded by U Auckland Research Committee & Health Research Council (NZ).

The Changing Pharmacodynamics of Metocurine Identify the Onset and Offset of Canine Gastrocnemius Disuse Atrophy

Immobilization of skeletal muscle results in disuse atrophy and resistance to nondepolarizing muscle relaxants. We studied the pharmacodynamics of metocurine (MTC) to identify the development and recovery of disuse-related resistance to MTC. Nineteen dogs underwent cast immobilization of a hind limb for as long as 3 weeks. Before, during, and after casting, dogs were intermittently anesthetized with thiamylal-N2O-fentanyl. The blood concentration of MTC and the corresponding degree of paralysis after a brief infusion were recorded and were used to characterize the pharmacokinetics and pharmacodynamics of MTC. Pharmacodynamic study of the response to MTC demonstrated resistance by the 4th day of casting. The effect-site concentration associated with 50% paralysis of twitch increased after 3 weeks from approximately 250 to 750 ng/ml. After cast removal, resistance persisted for 2 more weeks. Six weeks after cast removal, the effect-site concentration associated with 50% paralysis of twitch was normal in every dog. Within the context of this study of immobilization disuse atrophy, pharmacokinetic and pharmacodynamic characterization of antagonist responses can be used to infer muscle disuse-related changes in acetylcholine receptors.

Effect of Total End Range Time on Improving Passive Range of Motion

The objective of this study was to test the validity of the so-called total end range time (TERT) theory. This theory claims that the amount of increase in passive range of motion (PROM) of a stiff joint is proportional to the amount of time the joint is held at its end range, or total end range time. Proximal interphalangeal joint (PIP) flexion contractures were chosen as a model upon which to test the theory. Digital extension casts were used to hold the PIPs at the end range of extension. Fifteen patients with 20 PIP flexion contractures between 15° and 60° volunteered for this study. All contractures resulted from primary orthopedic conditions; none arose from a central nervous system lesion. Each joint was treated by two periods of continuous casting in extension: a 6-day period and a 3-day period. Patients were randomly assigned to one of two groups. Group A subjects wore the initial casts for 6 days and the subsequent casts for 3 days. Group B subjects wore the initial casts for 3 days and the subsequent casts for 6 days. Passive range of motion changes were measured under a controlled torque PROM technique before and after each casting period. The sum of the gains in PROM for all subjects during their 6 days of casting totaled 106° (x¯=5.3°). The total gain during the 3 days of casting was 60° (χ¯=3.0°). This finding was significant at the p < 0.005 level of confidence. The ratio of increase in PROM was 106°:60° = 1.766; the ratio of TERT was 6 days:3 days = 2.0. The authors concluded that the TERT theory was valid.

Lime-stabilized red mud bricks

Red mud is a waste material obtained from the aluminium extraction industry and consists mainly of the oxides of aluminium, iron and titianium. The present red mud production in the country is above two million tons every year, which is not being put to any worthwhile use except as a filler to a small extent in the preparation of roads. Efforts have been made at CBRI to produce burnt clay bricks by partially replacing the clay with red mud and fly-ash. In this process, the red mud is expected to find a major use shortly. Efforts have also been made to incorporate in the red mud a small percentage of lime and compress the mix at optimum moisture content in the form of bricks with a purpose of examining their strength and stability to the erosive action of water. A maximum wet compressive strength of 3.75 MN m−2 with 5% lime and 4.22 MN m−2 with 8% lime has been obtained after 28 days of casting and humid curing in the month of August. The red mud sample studied was obtained from the Indian Aluminium Company. The brick samples were studied for accelerated weathering and found suitable for use as a walling material for low-cost shelters. Modifications in the red mud mix, especially from the viewpoint of particle size distribution, have also been examined simultaneously by its part replacement with coarse-grained soil and fly-ash. The results indicate that the basis of the beneficial action of lime on red mud is predominantly chemical.