Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0012739 (disseminated intravascular coagulation)
 8,673 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To facilitate functional studies of novel myosins, we have developed a strategy for characterizing the mechanochemical properties of motors isolated by immunoadsorption directly from small amounts of crude tissue extracts. In this initial study, silica beads coated with an antibody that specifically recognizes the tail of myosin-V were used to immunoadsorb this motor protein from brain extracts. The myosin-containing beads were then positioned with optical tweezers onto actin filaments nucleated from Limulus sperm acrosomal processes and observed for motility using high resolution video DIC microscopy. The addition of brush border spectrin to the motility chamber enabled the growth of stable actin filament tracks that were approximately 4-fold longer than filaments grown in the absence of this actin crosslinking protein. The velocity of myosin-V immunoadsorbed from brain extracts was similar to that observed for purified myosin-V that was antibody-linked to beads or assessed using the sliding actin filament assay. Motile beads containing myosin-V immunoadsorbed from brain extracts bound poorly to nucleated actin filaments and were incapable of linear migrations following the addition of a different antibody that specifically recognizes the motor-containing head domain of myosin-V. Myosin-V motility was most robust in the absence of Ca2+. Interestingly, skeletal muscle tropomyosin and brush border spectrin had no detectable effect on myosin-V mechanochemistry. Myosin-V containing beads were also occasionally observed migrating directly on acrosomal processes in the absence of exogenously added actin.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:In vitro motility of immunoadsorbed brain myosin-V using a Limulus acrosomal process and optical tweezer-based assay. 761 69

To date, protrusion of pseudopodia has been considered to be primarily responsible for translocation of free-living amoebae and leukocytes of higher organisms. Although there is little question that the pseudopodium plays an important role, little attention has been given to the cortical structures that are responsible for cell-substratum anchorage in amoeboid movement. Here, we report on a new knobby foot-like structure in amoebae of a cellullar slime mold, Dictyostelium discoideum. These feet, each about 1 micron in diameter, appear transiently in multiple units at the base of certain pseudopodia where the amoeba contacts a partially deformable substrate. The feet were discovered, and their spatial and temporal behavior relative to pseudopodial anchorage and invasive locomotion were observed, by examining Dictyostelium amoebae using a DIC video microscope providing an 0.3 micron depth of field. Key evidence for the anchoring role of the knobby feet was obtained by investigating amoebae, flattened in a specially devised observation chamber, and attracted by chemotaxis towards 3',5' cyclic-adenosine monophosphate (cAMP). The cAMP was released by highly localized, pulsed UV-microbeam irradiation of caged cAMP. We show by indirect immunofluorescence that the knobby feet contain a high concentration of filamentous (F-) actin, myoB (a member of Dictyostelium myosin-I family), and alpha-actinin (an actin-binding protein). Interestingly, myoB exhibits a circular disposition around each foot. Neither myosin-II (conventional myosin) nor the 269 kD protein, which has been recently identified as a talin homologue of Dictyostelium [Kreitmeier et al., 1995: J. Cell Biol. 129:179-188], are concentrated at the feet. We propose that the knobby feet provide anchorage to the substratum needed by lamellipodia to exert projectile forces for invading narrow spaces or otherwise for a flattened amoeba to secure itself to the deformable substratum. Some forms of adhesion plaques in higher organisms such as "podosomes" or "invadopodia" may perform functions similar to the knobby feet, but appear to differ in life time, cytoskeletal organization and composition. We have named the knobby foot "eupodium."
 ...
PMID:Amoeboid movement anchored by eupodia, new actin-rich knobby feet in Dictyostelium. 909 56

A 22-year-old man developed unconsciousness, severe quadriplegia and muscle atrophy, and had markedly elevated serum creatine kinase levels after using the high-dose steroid and nondepolarizing neuromuscular blocking agents during the course of sepsis and DIC. On neurological examination, he was lethargic. The patient had generalized muscle weakness and wasting, and diminished deep tendon reflexes. He weakly responsed to painful stimuli on the legs. The motor nerve conduction study demonstrated decreased CMAP (compound muscle action potential) amplitudes. Motor and sensory nerve conduction velocities and their distal latencies were normal. Muscle biopsy revealed marked muscle fiber atrophy predominantly in type 2 fibers and numerous basophilic and a few necrotic fibers. Some atrophic fibers had decreased to absent myosin adenosine triphosphatase activity in their center. Accordingly, he was diagnosed as having acute quadriplegic myopathy (AQM), which has been reported mainly in Western countries. The mechanism of muscle fiber degradation in this myopathy is still unknown. On immunohistochemical analysis to our patient, enzyme activities of various proteases such as calpain, cathepsin B, and proteasomes were increased in the sarcoplasm, especially in the atrophic fibers. We suggest that lysosomal cathepsin, nonlysosomal calpain, and ATP-ubiquitin-proteasome proteolytic pathways participate in muscle fiber degradation in AQM.
 ...
PMID:[A case of acute quadriplegic myopathy]. 1108 98

Myofibroblasts from rat lung were cultivated. These cells in addition to beta- and gamma-cytoplasmic actins, expressed alpha-smooth muscle actin (alpha-SMA) and formed a system of "supermature" focal contacts, which were connected with thick stress-fibers expressing alpha-SMA and myosin II. Reduction of actin-myison contractility by inhibitors BDM and ML-7 lead to stress fiber reorganization, e.g., decrease in their thickness, a selective disappearance of alpha-SMA expression and myosin translocation from bundles to the cytoplasm. Using immunofluorescence, interference-reflection microscopy and morphometry, we have demonstrated that an inhibition of actin-myosin contractility also leads to dispersion of myofibroblastic focal contacts. Phase-contrast and DIC video-enhanced microscopy of live cells showed morphological reorganization at the leading edge after inhibitory treatment. Thus, actin-myosin contractility controls the structure of "supermature" focal contacts of myofibroblasts and alpha-SMA expression in stress fibers.
 ...
PMID:[Effect of actomyosin contractility on focal contacts of myofibroblasts and structure of stress fibers]. 1186 61

The goal of this study was to determine the morphological and sub-cellular mechanical effects of Rac activation on fibroblasts within 3-D collagen matrices. Corneal fibroblasts were plated at low density inside 100 microm thick fibrillar collagen matrices and cultured for 1-2 days in serum-free media. Time-lapse imaging was then performed using Nomarski DIC. After an acclimation period, perfusion was switched to media containing PDGF. In some experiments, Y-27632 or blebbistatin were used to inhibit Rho-kinase (ROCK) or myosin II, respectively. PDGF activated Rac and induced cell spreading, which resulted in an increase in cell length, cell area, and the number of pseudopodial processes. Tractional forces were generated by extending pseudopodia, as indicated by centripetal displacement and realignment of collagen fibrils. Interestingly, the pattern of pseudopodial extension and local collagen fibril realignment was highly dependent upon the initial orientation of fibrils at the leading edge. Following ROCK or myosin II inhibition, significant ECM relaxation was observed, but small displacements of collagen fibrils continued to be detected at the tips of pseudopodia. Taken together, the data suggests that during Rac-induced cell spreading within 3-D matrices, there is a shift in the distribution of forces from the center to the periphery of corneal fibroblasts. ROCK mediates the generation of large myosin II-based tractional forces during cell spreading within 3-D collagen matrices, however residual forces can be generated at the tips of extending pseudopodia that are both ROCK and myosin II-independent.
 ...
PMID:Dynamic assessment of fibroblast mechanical activity during Rac-induced cell spreading in 3-D culture. 1845 53

The use of fluorescent markers in living cells has increased dramatically in the recent years. The quantitative analysis of the images requires specific analysis software. Previously, the program Quimp was launched for quantitating fluorescent intensities at the membrane or the cortex of the cell. However, Quimp is not well suited to quantitate local membrane displacement. Here we present Quimp2 that is capable of tracking membrane subregions in time, which enables the simultaneous quantification of fluorescent intensities and membrane movement. Quimp2 has two new tools, (i) conversion filters to analyze movies obtained with fluorescent, DIC and phase contrast different microscopes, and (ii) a macro that calculates the local membrane displacement and provides various options to display the results. Quimp2 is used here to investigate the molecular mechanism of cell movement by correlating the dynamics of local membrane movement with the local concentration of myosin and F-actin.
 ...
PMID:Analysis of cell movement by simultaneous quantification of local membrane displacement and fluorescent intensities using Quimp2. 1920 51

Coagulation changes, thrombosis, and hemorrhage have been described in patients following N-methyl-3,4-methylenedioxymethylamphetamine (MDMA) intoxication who subsequently developed serotonin syndrome and rhabdomyolysis. The clinical features and mechanism of this remain poorly described. We describe 5 sequential cases admitted to critical care due to severe recreational MDMA toxicity where coagulopathy occurred, and discuss key clinical issues. All patients presented with hyperpyrexia then developed subsequent rhabdomyolysis accompanied by a coagulopathy within 24 hours of presentation. This included a severe thrombocytopenia, prolonged coagulation times, grossly elevated D-dimer levels, and hypofibrogenemia. Multiorgan dysfunction was seen in all patients, including stroke in one patient and major hemorrhage in another. In 2 cases, low-dose low-molecular-weight heparin was used early after presentation, with no significant bleeding complications. Blood products usage was high but variable between the patients with lower use in those who received low-molecular-weight heparin early. Other treatments included intravascular therapeutic cooling, renal replacement therapy with large filter pores and cyprohepatidine. Current evidence suggests that in this group, rhabdomyolysis with subsequent myosin release may be a profound activator of coagulation leading to disseminated intravascular coagulation. Myosin-activated coagulation seems a potential cause of MDMA-related coagulopathy in the setting of rhabdomyolysis and serotonin syndrome. Further studies are needed to validate this and explore the use of low-molecular-weight heparin to reduce the clinical effects of this coagulopathy.
 ...
PMID:N-Methyl-3,4-methylendioxymethamphetamine (MDMA)-related coagulopathy and rhabdomyolysis: A case series and literature review. 3268 91