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

It was demonstrated recently that, in contrast to large cerebral arteries, distensibility of cerebral arterioles is increased in stroke-prone spontaneously hypertensive rats (SHRSP). The goals of this study were to examine composition of normal cerebral arterioles, and to determine whether chronic hypertension alters relative composition of the arteriolar wall. Pial arterioles in normotensive Wistar Kyoto rats contain large amounts of smooth muscle, small amounts of elastin and basement membrane, and very little collagen. Hypertrophy of pial arterioles in SHRSP is characterized by increases in the elastic components, smooth muscle and elastin. The stiffer components, collagen and basement membrane either did not change or decreased. It is concluded that cerebral arterioles contain proportionately more smooth muscle and less collagen than large arteries, and that hypertrophy of cerebral arterioles in SHRSP is accompanied by a relative increase in the more elastic components of the arteriolar wall, which probably contributes to the increase in arteriolar distensibility.
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PMID:Composition and mechanics of cerebral arterioles in hypertensive rats. 320 16

Monolayer cultures of hepatocytes were shown to have good function when compared with suspended cells. The authors manufactured a new hybrid artificial liver containing hepatocyte monolayers and evaluated its function. Hepatocytes isolated from an adult dog liver were cultured on collagen coated borosilicated glass (10 X 20 X 0.04 cm). A long-stroke artificial liver module was constructed by stacking 200 glass plates bearing hepatocytes, which were viable and functioned well during 4 weeks in perfusion culture; glyconeogenesis = 110 ng/micrograms DNA/min, urea synthesis = 3.6 ng/micrograms DNA/min and albumin synthesis = 29 micrograms/10(6) cells/day at the 5th day of perfusion. The levels were maintained for 2 weeks. The new device was applied to anhepatic dogs (Group 3) and compared with untreated (Group 1) and plasma exchange dogs (Group 2). The survival times were 21.3 +/- 5.6 hours in Group 1 (N = 6), 27.8 +/- 4.0 hours in Group 2 (N = 3), and 55.0 +/- 10.3 hours in Group 3 (N = 4). The longest survival was 65 hours. Serum ammonia increased to over 2,000 micrograms/dl after 12 hours in Groups 1 and 2, but remained under 400 micrograms/dl in Group 3. This new type of hybrid system may be a pilot design for the complete artificial liver.
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PMID:A hybrid bioartificial liver composed of multiplated hepatocyte monolayers. 321 60

The morphology of cerebral microvessels was studied immunohistochemically and ultrastructurally in 6- to 9-month-old normotensive Wistar-Kyoto rats (WKY), spontaneously hypertensive rats (SHR), and stroke-prone SHR (SHRSP) with a systolic blood pressure of 138 +/- 15 mm Hg, 189 +/- 9 mm Hg, and 258 +/- 30 mm Hg respectively. Regions with major opening of the blood-brain barrier (BBB) were revealed by an i.v. injection of Evans Blue. Multifocal BBB opening with massive leakage of plasma constituents rich in fibrinogen-fibrin-related antigen occurred in SHRSP with a blood pressure above 210-220 mm Hg. BBB-leakage sites were found in the cerebral cortex and the basal ganglia, most frequently in the arterial border zones. The perivascular tissue spaces were dilated within the BBB-leakage sites, in particular around arterioles. Damaged endothelial and smooth muscle cells were replaced by fibrin-like material, multiple layers of basement membranes and bundles of collagen fibrils surrounded by proliferated fibroblasts. The degenerative-infiltrative-proliferative disease process transformed short segments of single arterioles into severely thickened, tortuous and stenotic vessels. Fibrinoid degeneration, formation of microaneurysms and fibrin-rich vascular occlusions were observed. In contrast, only minor or no vascular alterations were seen in regions with preserved BBB in SHRSP and SHR. A severely increased intraluminal pressure load appears to be of major pathogenetic importance for breakdown of the BBB and initiation of the vascular disease process in SHRSP. However, since only short segments of a limited number of widely separated vessels are severely affected, and the number of affected vessels increase towards arterial end and border zones, additional predisposing and aggravating factors may play significant roles in the development of fibrinoid vascular lesions in arterial hypertension.
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PMID:Cerebral microangiopathy in stroke-prone spontaneously hypertensive rats. An immunohistochemical and ultrastructural study. 334 82

The effects of low daily oral doses of aspirin (40 mg/day) on platelet aggregability and serum thromboxane B2 concentrations were studied in 19 poststroke patients. Although platelet aggregation was reduced significantly after 1 week, there was wide individual variation in the inhibition of platelet function in spite of marked decreases of serum thromboxane B2 concentrations by greater than 90% (from 224 +/- 58 to 8 +/- 8 ng/ml). There was no correlation between collagen-induced platelet aggregability and serum thromboxane B2 concentration before aspirin administration in the range 100-350 ng/ml, but after 1 week of repeated administration of aspirin, there was a correlation between platelet aggregability and serum thromboxane B2 concentrations of less than 25 ng/ml (r = 0.68, p less than 0.01). However, platelet inhibition was insufficient even in some patients with markedly decreased thromboxane B2 concentrations (less than 5 ng/ml). Our results suggest that individual variation of platelet aggregability in response to low-dose aspirin may be due to variation not only in the degree of inhibition of thromboxane A2 production but also in the relative dependence of platelet aggregation on extra-arachidonic pathways.
Stroke 1988 Jun
PMID:Individual variation in platelet aggregability and serum thromboxane B2 concentrations after low-dose aspirin. 337 61

Urinary excretion of total hydroxyproline being an indicator of the metabolism of systemic collagen was determined in 104 patients with ischaemic stroke and in 45 controls. The determinations were done by the method of Prockop-Udenfried in the urine of patients after 2 days on a non-collagen diet. Increased excretion of hydroxyproline was found in the subgroup of patients with high-grade paresis or paralysis, while in the subgroup with mild paresis these results were normal. The excretion of hydroxyproline in patients with severe paralysis increased during 3-60 days after stroke and then decreased in the period from 60 days to 5 years.
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PMID:[Urinary excretion of hydroxyproline in patients with ischemic stroke]. 338 Feb 61

148 patients with various forms of cerebrovascular disease (CVD) were studied by means of a multiparametric analysis of in vitro platelet aggregation, based on the following six parameters: ADP and epinephrine primary and secondary aggregation thresholds and percent maximum aggregation induced by optimal concentrations of ADP and epinephrine. These patients were assigned to four study groups, according to clinical diagnosis supported by CT scan, of transient ischemic attack and reversible neurological deficit (TIA-RIND), or completed stroke, in the presence or absence respectively of antiplatelet medical treatment at the time of the study. A statistically significant increase of the in vitro platelet aggregation was found in 44.4% of the untreated TIA-RIND patients and in 33.9% of the untreated stroke patients. However this last group showed a higher percentage of very marked hyperaggregation. Differences between the two treated study groups and controls were not significant. No difference was found in collagen- and ristocetin-induced aggregation between the patient groups and the controls.
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PMID:A multiparametric index of platelet in vitro aggregation in cerebrovascular disease. 342 15

Not infrequently, great difficulty is encountered in the operation for advanced cervical carcinoma of the uterus in dissecting cancerous tissues and controlling incidental bleeding. The CUSA is a major achievement of modern ultrasonic technology, and has been used by us to overcome such difficulties in 6 cases of total pelvic exenteration, 4 of anterior pelvic exenteration, 1 of posterior pelvic exenteration, 2 of cardinal ligament extirpation and 21 of radical hysterectomy. The handpiece of the CUSA contains a hollow titanium tip which vibrates longitudinally along its axis, driven by a magnetostrictive transducer. The vibration occurs with a frequency of 23 kHz and with an adjustable stroke of 0-300 microns. The tip of the device, placed in contact with the target tissues, destroys and emulsifies the cell membranes, which are irrigated and removed through a built-in suction tube. Since vessels larger than 0.5mm in diameter, nerves and fibrous tissue capsules contain much collagen, they rebound with the ultrasonic vibration waves emitted by the CUSA, and consequently they are left unimpaired by the procedure. It was noted in our operations that the larger the degree of tip excursion of the CUSA, the greater was the power added to fragment the target tissues. The effectiveness also depended upon the amount of water contained in the tissues. A very accurate sensation of the consistency of tissues was obtainable through the tip of the device in contact with them. This tactile feedback was quite helpful in enabling us to differentiate between target tissues. A clear visualization of detailed structures of vasculature and nerves in the pelvic cavity was attained as a result of sweeping dissection using the CUSA, and thereby extensive elimination of the cancerous tissues and lymph nodes was facilitated.
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PMID:[Usage of the CUSA (cavitron ultrasonic surgical aspirator) in radical surgery of cervical carcinoma of the uterus]. 359 94

The feeding of large amounts of fish or fish oils to healthy volunteers has been shown to reduce plasma triglycerides and platelet aggregation, and prolong the skin bleeding time. To determine whether a commercially available marine oil (MaxEpa) would have similar effect in stroke patients, we performed a double-blind, placebo-controlled study in 11 patients (7 men, 4 women) with completed stroke (7) or transient ischemic attacks (TIA's) (4). Ten 1 ml opaque capsules containing either MaxEpa or olive oil were given daily for 6 weeks, and then the patients were crossed-over. Aspirin was avoided during the trial. The data were analyzed by paired-sample t-tests. A significant reduction was found in serum triglycerides, but total serum cholesterol and HDL cholesterol were unaffected. The bleeding time was modestly prolonged after 3 weeks of treatment, but the differences between MaxEpa and olive oil treatments were not significant at 6 weeks. Aside from an increase in collagen-stimulated malondialdehyde formation no other statistically significant changes in hemostatic factors were observed. We conclude that the ingestion of up to 10 MaxEpa capsules daily for 6 weeks has little influence on such established risk factors as cholesterol concentration and platelet function in patients with stroke or TIA's.
Stroke
PMID:A double-blind, placebo-controlled trial of fish oil concentrate (MaxEpa) in stroke patients. 389 95

The effect of a selective thromboxane (TX) synthetase inhibitor (OKY-046), alone and in combination with a very low dose of aspirin, on the platelet function was studied in healthy and diseased subjects. A single dose of 100 mg OKY-046 was orally administered to patients with ischemic cerebrovascular disease (CVD) and healthy volunteers. TXB2 generation and platelet aggregation were measured before and at 1, 4, 6 and 8hr after dosing. In addition, after the administration of a very low dose of aspirin (0.1-0.25 mg/kg/day) for at least one month, a single dose of OKY-046 was given to CVD patients. TXB2 generation and platelet aggregation were measured in the same manner as OKY-046 alone. The effect of OKY-046 on platelet aggregation induced by arachidonic acid (AA) was different in each subject whereas platelet TXB2 generation was almost completely inhibited in all of the patients and healthy volunteers. OKY-046 had a slight inhibitory effect on collagen induced aggregation. A combination of OKY-046 with a very low dose of aspirin, on the other hand, produced additional inhibition of the platelet aggregation induced by both AA and collagen. The present results suggest that the accumulation and metabolism of cyclooxygenase products that accumulate when TX synthetase is blocked, differ in each subject, additional inhibition is caused by the combined use of TX synthetase inhibitor and a very low dose of aspirin because the very low dose of aspirin partially reduces the proaggregatory cyclooxygenase products that accumulate when TX synthetase is blocked.(ABSTRACT TRUNCATED AT 250 WORDS)
Stroke
PMID:A new approach to antithrombotic therapy--evaluation of combined therapy of thromboxane synthetase inhibitor and very low dose of aspirin. 393 2

We tested the antiplatelet effects of low-dose aspirin in patients with occlusive cerebrovascular disease, because conventional dosage aspirin inhibits vascular synthesis of prostacyclin at the same time that it inhibits platelets. The effects on platelet function and thromboxane A2 synthesis of 40 mg of aspirin daily or 40 mg aspirin plus dipyridamole were measured in 23 patients starting within a week after the onset of cerebral ischemia. All patients had normal baseline platelet aggregation responses to four stimuli: arachidonate, epinephrine, adenosine diphosphate and collagen. The generation of thromboxane A2 by platelets, measured as serum thromboxane B2, was also normal. After 3 to 7 days of low dose aspirin therapy, platelet aggregation responses were suppressed to the extent observed with higher dosage aspirin. Serotonin release during platelet aggregation was inhibited by more than 95% and thromboxane B2 levels in clotted blood fell by more than 95%. Responses to aspirin treatment were similar in patients with transient ischemic attacks and in those with stroke and were also similar in both sexes. No differences in platelet responses were observed between patients receiving aspirin alone and aspirin plus dipyridamole. Thus 40 mg aspirin daily inhibited platelet responses as effectively as higher doses of aspirin in patients who had recent cerebral ischemia and showed a cumulative antiplatelet effect.
Stroke
PMID:Effects of low dose aspirin on platelet function in patients with recent cerebral ischemia. 396 66


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