Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We observed significant lesions of the carotid artery siphon in two young subjects with fatal stroke. Because stroke in children and adolescents is uncommon and poorly understood, we examined the internal carotid artery in the 'siphon' of the skull in 24 unselected, but nearly consecutive autopsies. The age range was 10 days to 38 years, with 11 males and 13 females, six blacks, and 18 whites. In no case was stroke the cause of death. Intimal lesions of two types were found in the carotid siphon of all cases. (1) The first was focal splitting and/or duplication of the internal elastic lamina with variable proliferation of smooth muscle. The resulting 'fibrous' plaques or cushions, when severe, were usually found at natural bends in the artery. The number and severity of this type of lesion increased with age, but there were no differences in severity or distribution when compared by sex, race, or mode of death. (2) The second was internal elastic calcification which was found in all cases older than 9. This was increasingly severe with age. Although the frequency of the vascular lesions was surprisingly high, the relationship of either type to dissecting aneurysm or other stroke lesion remains unclear.
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PMID:The internal carotid artery siphon in children and adolescents. 186 91

Hyperbaric oxygen (HBO) has become a useful treatment in clinical diseases. All the treatment profiles (Death/Time) were performed under the safe limit of unit pulmonary toxicity dose (UPTD). Between June 1976 and December 1987, we had treated 1288 cases with HBO. The effective rates (cure or improvement) were 97.5% for decompression sickness, 96.3% for chronic osteomylitis, 90% for chronic skin ulcer, 89.4% for crush injury, 81.3% for gas intoxication, 76.1% for burn injury, 73.3% for cerebrovascular accident, 57.1% for gas gangrene, 50% for retinal artery insufficiency, and 45.5% for head or spinal cord injury. Only 3 patients suffered from oxygen toxicity and relieved immediately. To the serious decompression sickness, the comparative study between the conventional treatment table and our modified table revealed increased cure rate(25.8% versus 50.0%, P less than 0.05), and decreased recurrence rate (16.1% versus 4.1%, P less than 0.05). In burn patients with 35-70% area involved and 15-45 years of age, the comparative analysis showed a reduced mortality rate of 6.8% for the HBO treated group as opposed to 14.8% for the non-HBO treated group, P less than 0.05.
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PMID:Hyperbaric oxygen therapy in clinical application. A report of a 12-year experience. 280 85

We advance a structural model to account for the rapid elastic element seen in mechanical transient experiments on vertebrate skeletal muscle (A.F. Huxley & Simmons 1971 Nature, Lond. 233, 533-538). In contrast to other crossbridge models, ours does not envisage a myosin rod made up of two rigid portions connected by a hinge, but rather a gradually bending rod portion connecting the heads to the thick filament shaft. We propose that, in relaxed muscle, the subfragment 2 (S2) portion of the myosin rod is bound to the thick filament shaft by ionic interactions analogous to those between the light meromyosin (LMM) portions of the rod that constitute the body of the shaft. These interactions probably involve the alternating zones of positive and negative charge seen in myosin rod amino acid sequences. As the crossbridge cycle that generates tension begins, we propose that part of S2 detaches from the thick filament shaft and bends to enable the myosin head to attach to actin. When tension develops in the crossbridge, the S2 is straightened and more of it becomes detached from the shaft so that the junction between S2 and the myosin heads moves 3-4 nm axially. As tension declines at the end of the crossbridge stroke, we propose that S2 rebinds to the thick filament shaft and that this provides the restoring force to return the junction of the heads and S2 to its original axial position. Thus this movement would have the characteristics of an elastic element; detailed calculations indicate that it would have properties similar to those observed experimentally. Furthermore, this model can account for the radial attractive force seen in rigor and in contracting muscle, the decrease in stiffness when interfilament spacing is increased in skinned muscle, and the increased rate of proteolysis observed at the S2-LMM junction in contracting muscle.
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PMID:A model to account for the elastic element in muscle crossbridges in terms of a bending myosin rod. 288 7

During capacitation, mammalian spermatozoa gain the ability to penetrate the cumulus cell matrix (CCM). The role of hyperactivated motility for this capacity is uncertain. In the present study, hamster sperm were observed during penetration and progression through the CCM, and flagellar beat patterns were quantitated by characterization of the underlying flagellar bends. Small numbers of sperm were added to cumulus masses slightly compressed on a slide (150 micron depth), and penetration was videorecorded using interference contrast optics. During penetration of the cumulus surface, sperm did not generate the large flagellar bends and asymmetric beats that are hallmarks of hyperactivation in low viscosity media. Instead, they entered slowly using high-frequency, low-amplitude sinusoidal flagellar motions. Within the CCM, sperm continued to move slowly, and they exhibited three distinct patterns of motility. The first was sinusoidal, produced by alternating, propagated bends: principal bends (PB) moved the head away from the beat midline, with the convex edge of the head leading, and reverse bends (RB) had the opposite curvature. The second pattern was asymmetric and sinusoidal: an extreme RB developed in the distal flagellum, was propagated distally, and was followed by a PB of less curvature. The third motility pattern was a hatchet-like stroke of the sperm head which resulted when an extreme, nonpropagated PB developed slowly in the proximal midpiece, and was released rapidly. In this mode there were no reverse bends, and sperm did not progress. There were subpopulations of capacitating sperm in free-swimming medium which had these same bend types and motility patterns, suggesting that qualitative flagellar movement may not change during CCM penetration. Sperm velocity in the CCM was not strongly correlated with flagellar beat kinematics, suggesting local heterogeneity in cumulus mechanical resistance and/or differences in interaction of the matrix with the surfaces of individual sperm. An effective viscosity of the cumulus near its border was estimated to be of the order of 1-4 P.
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PMID:Kinematics of hamster sperm during penetration of the cumulus cell matrix. 322 Apr 30

In Elliptio complanatus lateral cilia, two distinct patterns of filament termination can be discerned. In one case, all nine filaments are present and all are single; in the second, at least one filament is missing but doublets are still present. These probably represent different configurations within one cilium in different stroke positions; to get from one to the other, some peripheral filaments must move with respect to others. The data are consistent with the hypothesis that the filaments themselves do not change length, but rather slide past one another to accommodate increasing curvature. The bent regions of the cilium are in the form of circular arcs. In a few cases, apparent displacement of filaments at the tip (Deltal) can be shown to be accounted for if we assume that all differences are generated within these arcs. The displacement per degree of bend is 35 A. Regions of bent arc are initially confined to the base of the cilium but move up the shaft as straight regions appear below them. From the relationship between arc length and radius of curvature, a shaft length that is the unit that initially bends and slides may be defined. Quantal displacements of the length of one 14S dynein may perhaps occur at sites between filaments at opposite sides of such a unit as sliding occurs.
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PMID:Morphological aspects of ciliary motility. 605 May 97

The PFC emulsions have had a developmental history of promise as yet unfulfilled. Today, second-generation PFC emulsions are poised with the right gas-carrying capabilities to be able to make significant contributions to oxygen transport and delivery. The dream of stable, safe, easily transportable intravenous fluid, with universal rapid application is not yet at hand. However, we appear to be a great deal closer than in the mid 1980s. If these 40% volume-to-volume emulsions prove safe, then an entirely new realm of therapeutic options will become available. Not only will the uses for trauma and acute blood loss replacement become a reality, but extremes of euvolemic hemodilution may become possible. The use of these compounds for prevention of stroke, ischemic organ salvage, and prevention of air embolism or decompression sickness are particularly exciting. It is clear from the recent developments in PFC technology that some product will come to market in the not-too-distant future. How such a PFC will be utilized as compared with hemoglobin preparations is yet to be discerned, but the two concepts are quite different. Each will have its own specific indications.
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PMID:Perfluorocarbon emulsions: one approach to intravenous artificial respiratory gas transport. 763 52

The haemodynamic basis for paradoxical embolization in patients with stroke and decompression sickness has not yet been fully elucidated. Therefore right and left atrial pressures were measured simultaneously with peroperatively placed catheters after coronary artery bypass grafting in 17 patients with sinus rhythm and normal left ventricular function. Recordings were made both during spontaneous breathing and positive pressure ventilation. A cyclic pressure reversal in which right atrial pressure exceeded left atrial pressure was reproducibly recorded. It started on average 215 +/- 5 ms (mean +/- SEM) after the onset of the electrocardiographic P-wave, lasted on average 179 +/- 14 ms and had a maximal amplitude of on average 4.1 +/- 0.3 mmHg. During the expiration phase of spontaneous breathing and inspiration phase of positive pressure ventilation, the onset of the pressure reversal occurred later, its duration was shorter and its amplitude smaller. These observations demonstrate the presence of a cyclic inter-atrial pressure reversal and illustrate the importance of the breathing mode for the time course and amplitude of this reversal.
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PMID:Influence of the breathing mode on the time course and amplitude of the cyclic inter-atrial pressure reversal in postoperative coronary bypass surgery patients. 837 16

Therapy for acute ischemic stroke can be approached in two basic ways: first, by an attempt to restore or improve blood flow in an occluded vascular territory and, second, via therapy directed at the cellular and metabolic targets. As local anoxia and energy failure are the initiating cellular stage in ischemia, the inhalation of oxygen at increased atmospheric pressures might be effective. Treatment of acute focal cerebral ischemia with hyperbaric oxygen (HBO) has been reported in animals and humans. In general, the results of research in animals have suggested a promising role for the use of HBO. More than 400 cases of human ischemic stroke treated with HBO have been reported. In about half of the cases, improvement in status has been claimed on clinical or electroencephalographic grounds. In fact, the effectiveness of HBO in most disease processes other than carbon monoxide poisoning and decompression sickness is a subject of major ongoing debate. This short review will attempt: (1) to recall some early experiments involving HBO in the treatment of acute ischemia: (2) to point out some conflicting results regarding the role of HBO on cellular and metabolic disorders; and (3) to determine the possibility of a future role for HBO therapy in acute ischemic stroke.
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PMID:Hyperbaric oxygen in the treatment of acute ischemic stroke: an unsettled issue. 926 Aug 51

Decompression injuries are potentially life-threatening incidents, generated by a rapid decline in ambient pressure. Although typically seen in divers, they may be observed in compressed air workers and others exposed to hyperbaric environments. Decompression illness (DCI) results from liberation of gas bubbles in the blood and tissues. DCI may be classified as decompression sickness (DCS) or arterial gas embolism (AGE), depending on where the gas bubbles lodge. DCS occurs after longer exposures to a hyperbaric environment with correspondingly larger up-take of inert gas. DCS may be classified into type 1 with cutaneous symptoms and musculoskeletal pain only or type 2 with neurologic and/or pulmonary symptoms as well. AGE usually results from a pulmonary barotrauma, and with cerebral arterial involvement, the symptoms are similar to a stroke. The most important therapy, in the field, is oxygen resuscitation with the highest possible concentration and volume delivered. The definitive treatment is rapid recompression with hyperbaric oxygen therapy. Additional therapeutic measures are discussed.
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PMID:[Severe diving accidents: physiopathology, symptoms, therapy]. 1084 May 40

Recent structural evidence indicates that the light chain domain of the myosin head (LCD) bends on the motor domain (MD) to move actin. Structural models usually assume that the actin-MD interface remains static and the possibility that part of the myosin working stroke might be produced by rotation about the acto-myosin interface has been neglected. We have used an optical trap to measure the movement produced by proteolytically shortened single rabbit skeletal muscle myosin heads (S-1(A1) and S-1(A2)). The working stroke produced by these shortened heads was more than that which the MD-LCD bend mechanism predicts from the full-length (papain) S-1's working stroke obtained under similar conditions. This result indicates that part of the working stroke may be caused by motor action at the actin-MD interface.
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PMID:An unexpectedly large working stroke from chymotryptic fragments of myosin II. 1103 47


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