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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Single-element and/or rosette strain gages were bonded to mandibular cortical bone in Galago crassicaudatus and Macaca fascicularis. Five galago and eleven macaque bone strain experiments were performed and analyzed. In vivo bone strain was recorded from the lateral surface of the mandibular corpus below the postcanine tooth row during transducer biting and during mastication and ingestion of food objects. In macaques and galagos, the mandibular corpus on the balancing side is primarily bent in the sagittal plane during mastication and is both twisted about its long axis and bent in the sagittal plane during transducer biting. On the working side, it is primarily twisted about its long axis and directly sheared perpendicular to its long axis, and portions of it are bent in the sagittal plane during mastication and molar transducer biting. In macaques, the mandibular corpus on each side is primarily bent in the sagittal plane and twisted during incisal transducer biting and ingestion of food objects, and it is transversely bent and slightly twisted during jaw opening. Since galagos usually refused to bite the transducer or food objects with their incisors, an adequate characterization of mandibular stress patterns during these behaviors was not possible. In galagos the mandibular corpus experiences very little transverse bending stress during jaw opening, perhaps in part due to its unfused mandibular symphysis. Marked differences in the patterns of mandibular bone strain were present between galagos and macaques during the masticatory power stroke and during transducer biting. Galagos consistently had much more strain on the working side of the mandibular corpus than on the balancing side. These experiments support the hypothesis that galagos, in contrast to macaques, employ a larger amount of working-side muscle force relative to the balancing-side muscle force during unilateral biting and mastication, and that the fused mandibular symphysis is an adaption to use a maximal amount of balancing-side muscle force during unilateral biting and mastication. These experiments also demonstrate the effects that rosette position, bite force magnitudes, and types of food eaten have on recorded mandibular strain patterns.
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PMID:Mandibular function in Galago crassicaudatus and Macaca fascicularis: an in vivo approach to stress analysis of the mandible. 10 47

Shone's anomaly, a congenital cardiac malformation, consists of multiple levels of left heart obstruction including supravalvar mitral ring, parachute mitral valve, subaortic stenosis, and coarctation. The prognosis for patients with Shone's anomaly is poor. To assess operative results and late outcome, we reviewed the records of 30 consecutive patients seen with Shone's anomaly at our institution between 1966 and 1989. Anatomical diagnoses in these patients were supravalvar mitral ring (22 patients), mitral valve abnormalities including parachute mitral valve, fused chordae, or single papillary muscle (26 patients), subaortic gradients (26 patients), and coarctation (29 patients). Nineteen patients had all four lesions. Other common defects were bicuspid aortic valve (19 patients) and ventricular septal defect (20). Two patients were treated medically. The other 28 patients required 84 operative procedures with 18 patients undergoing more than one procedure. Operations included coarctation repair (28 patients), mitral valve repair or replacement (11), ventricular septal defect closure (8), subaortic resection (8), and complex left ventricular outflow tract reconstruction or bypass (4). Age at first operation ranged from 7 days to 7 years (median age, 3 months). There were no operative deaths at the first operation. However, mortality rose to 24% (4/17) after the second operation. All operative deaths were secondary to severe mitral valve disease. The survivors have been followed from 1 to 16 years (mean follow-up, 6 +/- 1 years). There were no late or sudden deaths. Morbidity has included stroke (1), gastrointestinal bleeding (2), permanent heart block (1), and persistent congestive heart failure (6).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Shone's anomaly: operative results and late outcome. 236 86

The relationship between seizure propensity and the vascular anatomy of the anterior cerebral arteries, or stroke induced by unilateral ligation of the common carotid artery, was investigated utilizing well differentiated colonies of seizure-prone (SP) and non-seizure-prone (NSP) gerbils. Twenty SP and 20 NSP gerbils were perfused with a latex dye and the vascular patterns of the anterior cerebral arteries (ACA) were analyzed. In addition, 30 SP and 30 NSP gerbils were subjected to unilateral ligation of the common carotid artery and the number developing stroke (determined by clinical observation as well as by microscopic examination of the brain) was recorded. We found that in all animals the ACAs formed a fused-central vessel which vascularized the olfactory bulbs, as well as two lateral vessels (rostral arteries) that vascularized a previously undescribed nasal plexus. Neither the vascular pattern of the ACA, nor the frequency of occurrence of stroke following unilateral ligation was related to seizure propensity.
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PMID:Brain vasculature and induced ischemia in seizure-prone and non-seizure-prone gerbils. 705 30

In order to clarify insulinotropic effects of the myelin basic protein (MBP) we studied mode of association and distribution of MBP in the pancreatic islets and tested the insulin-releasing activity of various MBP peptides. Rat pancreatic islets were first stimulated in a static incubation with 10 microM bovine MBP (bMBP) at a substimulatory (3.5 mM) glucose concentration. The islets exposed to MBP released significantly more insulin and glucagon in a second incubation in the absence of added stimulant and in the presence of 11.5 mM arginine than the incubated, non-stimulated islets and islets initially stimulated with 15 mM glucose. Response to stimulation with 15 mM glucose in the second incubation by islets exposed first to MBP was impaired compared to incubated, non-stimulated islets. Immunoelectron microscopy showed that MBP had entered into the islet cells and associated with membranes of intracellular vacuoles, most of which represented enlarged, often fused insulin granules. MBP was also present at the islet edge and in the intercellular spaces. Of the purified MBP peptides of sizes of 4.8-13.6 kDa, produced from the digestion with brain acid proteinase and with pepsin and covering the entire bMBP sequence, only the large peptides (1-88, 9.8 kDa and 43-169, 13.6 kDa) stimulated insulin secretion significantly. Heterogeneous peptide mixtures, obtained from a time-course digestion of bMBP by myelin calcium-activated neutral protease, consisting of peptides of approximate molecular weights of 8-11 kDa and larger, also stimulated insulin release. The glucagon-releasing activity of MBP peptides was low and followed the same pattern as the insulin-releasing activity. The present results suggest that MBP-induced fusion of the membranes of hormone granules is involved in MBP-induced insulin release. The hormone-releasing activity of the large peptides in addition to that of the intact molecule is explained as being due to the ability of these peptides to associate with membranes. MBP-induced hormone release and related effects could be associated with neuropathological conditions such as stroke and multiple sclerosis.
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PMID:Evidence supporting membrane fusion as the mechanism of myelin basic protein-induced insulin release from rat pancreatic islets. 749 48

Four related series of substituted quinoxalinediones containing angular fused-piperidine rings have been synthesized as alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonists with potential as neuroprotective agents, primarily for acute therapy immediately following a stroke. The compounds were tested for their affinity to the AMPA, kainate, and strychnine-insensitive glycine receptor sites. In AMPA binding, the most potent compound was 27a (PNQX, IC50 = 63 nM), with affinity comparable to the literature standard 1 (NBQX, IC50 = 52 nM). Other 6-nitro analogs from the 9-aza series had comparable affinity at the AMPA receptor, as did 6-nitro-8-aza derivatives such as 13a (iPNQX, IC50 = 290 nM). The receptor binding profile of 27a differed from that of 1 in that 27a possessed significant affinity at the glycine site of the N-methyl-D-aspartate (NMDA) receptor, whereas 1 was essentially inactive. Three compounds, 26c, 26d, and 26e, demonstrated moderate selectivity for kainate relative to AMPA receptors. Selected analogs reported herein as well as in the literature were superimposed to generate an AMPA pharmacophore model, and 6-substituted compounds from the PNQX and iPNQX series were combined and analyzed via quantitative structure-activity relationship techniques. Compounds with high affinity at non-NMDA receptors were further characterized in functional assays in neuronal cell culture and in a cortical wedge preparation. Both 1 and 27a showed comparable effectiveness in an AMPA- and kainate-induced excitoxicity assay. Both inhibited AMPA-induced depolarizations in the cortical wedge. However, 27a also inhibited spontaneous epileptiform discharges in the cortical wedge (reversed by glycine), while 1 was ineffective. The combination of AMPA and NMDA antagonist activity may contribute to the 30-fold difference in potency between 27a and 1 in the maximal electroshock convulsant assay in mice. The significant in vivo potency of 27a suggests that it has potential clinical utility.
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PMID:Synthesis of 1,4,7,8,9,10-hexahydro-9-methyl-6-nitropyrido[3,4-f]- quinoxaline-2,3-dione and related quinoxalinediones: characterization of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (and N-methyl-D-aspartate) receptor and anticonvulsant activity. 756 4

Fused silicon dioxide, multiparameter flow transducers with 50 microns internal square cross section and approximately 60 microns length can simultaneously measure DC and RF impedance as well as fluorescence and multiple-angle light scattering. A spherical version of such a transducer was mounted in an EPICS CVA flow-cell housing and was installed on a research prototype equipped with an argon-ion laser. The signal that was produced by the spherical transducer with EPICS DNA-Check beads was 1.73 times greater than that produced with the standard cylindrical flow cell. Similarly, with EPICS Immuno-Brite beads, the average ratio was 1.96. The Coulter impedance and light-scattering measurements were similar to those produced with the conventional cylindrical outside flow cell, although the internal cross section of the sphere was square and that of the cylinder was circular. The theoretical arguments of Leif and Wells have been demonstrated to be correct. At present, monolithic, spherical fused-silica transducers are the optimal design for combined electrooptical, multiparameter flow cytometry analyzers.
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PMID:Use of a spherical multiparameter transducer for flow cytometry. 766 29

The blood clotting enzyme thrombin plays a central role in the aetiology of occlusive disorders such as stroke and acute myocardial infarction. During fibrinolytic therapy with plasminogen activators, thrombin is neutralized by anticoagulative drugs. In order to combine plasminogen-activating and thrombin-inhibitory activities we constructed chimeric derivatives of recombinant single-chain, urokinase-type plasminogen activator (rscu-PA) which comprise the kringle and protease domain of rscu-PA fused via a linker sequence to a thrombin-inhibitory domain. The inhibitory domain contains a sequence element directed to the active site of thrombin and a sequence taken from either hirudin or the human thrombin receptor both binding to the fibrinogen recognition site of thrombin. Analysing different sets of point mutants showed that the linker between the protease domain and the active site-directed sequence is contributing significantly to the thrombin-inhibitory potential. Kinetic analysis of thrombin inhibition revealed that most of the chimeras tested competitively inhibit the thrombin-mediated cleavage of a peptide substrate in a concentration-dependent manner; however, in two examples the insertion of one glycine residue into the active site directed-sequence abolished the blockade of the active site. This supports the conclusion that the chimeras with high thrombin-inhibitory potential interact with the active site and the fibrinogen recognition site of thrombin.
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PMID:Construction and structure-activity relationships of chimeric prourokinase derivatives with intrinsic thrombin-inhibitory potential. 900 43

We determined the changes and responses in the electroencephalogram (EEG) induced by transcranial magnetic stimulation (TMS) of the scalp of five healthy men. The center of a circular coil was positioned at the vertex, and 80 stimulations were administered clockwise with the maximum output of electric current. To reduce stimulus artifacts, we created a circuit that blocked the input for 150 ms after stimulation. EEGs were recorded from F3,4, C3,4, P3,4, and T3,4. The following results were obtained: (1) slowing of the EEG was observed immediately (150 m) after each stimulation. The incidence of changes ranged from 25-80%; their duration ranged from 200-600 ms. (2). Electroencephalographic responses in the averaged form appeared as gentle positive waves. In some subjects and leads, 1 to 3 negative peaks were fused. The methods used in the present study may be useful in evaluating the sensitivity to TMS of patients with stroke and other types of brain injury.
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PMID:Transcranial magnetic stimulation-induced changes in EEG and responses recorded from the scalp of healthy humans. 927 34

Fibroblast growth factors (FGFs) are being investigated in human clinical trials as treatments for angina, claudication, and stroke. We designed a molecule structurally unrelated to all FGFs, which potently mimicked basic FGF activity, by combining domains that (1) bind FGF receptors (2) bind heparin, and (3) mediate dimerization. A 26-residue peptide identified by phage display specifically bound FGF receptor (FGFR) 1c extracellular domain but had no homology with FGFs. When fused with the c-jun leucine zipper domain, which binds heparin and forms homodimers, the polypeptide specifically reproduced the mitogenic and morphogenic activities of basic FGF with similar potency (EC50 = 240 pM). The polypeptide required interaction with heparin for activity, demonstrating the importance of heparin for FGFR activation even with designed ligands structurally unrelated to FGF. Our results demonstrate the feasibility of engineering potent artificial agonists for the receptor tyrosine kinases, and have important implications for the design of nonpeptidic ligands for FGF receptors. Furthermore, artificial FGFR agonists may be useful alternatives to FGF in the treatment of ischemic vascular disease.
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PMID:Semirational design of a potent, artificial agonist of fibroblast growth factor receptors. 1058 18

Fused symphyses, which evolved independently in several mammalian taxa, including anthropoids, are stiffer and stronger than unfused symphyses. This paper tests the hypothesis that orientations of tooth movements during occlusion are the primary basis for variations in symphyseal fusion. Mammals whose teeth have primarily dorsally oriented occlusal trajectories and/or rotate their mandibles during occlusion will not benefit from symphyseal fusion because it prevents independent mandibular movements and because unfused symphyses transfer dorsally oriented forces with equal efficiency; mammals with predominantly transverse power strokes are predicted to benefit from symphyseal fusion or greatly restricted mediolateral movement at the symphysis in order to increase force transfer efficiency across the symphysis in the transverse plane. These hypotheses are tested with comparative data on symphyseal and occlusal morphology in several mammals, and with kinematic and EMG analyses of mastication in opossums (Didelphis virginiana) and goats (Capra hircus) that are compared with published data on chewing in primates. Among mammals, symphyseal fusion or a morphology that greatly restricts movement correlates significantly with occlusal orientation: species with more transversely oriented occlusal planes tend to have fused symphyses. The ratio of working- to balancing-side adductor muscle force in goats and opossums is close to 1:1, as in macaques, but goats and opossums have mandibles that rotate independently during occlusion, and have predominantly vertically oriented tooth movements during the power stroke. Symphyseal fusion is therefore most likely an adaptation for increasing the efficiency of transfer of transversely oriented occlusal forces in mammals whose mandibles do not rotate independently during the power stroke.
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PMID:Why fuse the mandibular symphysis? A comparative analysis. 1091 27


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