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

Oxidative stress has been implicated in the pathogenesis of hypertension. The aim of the present study was to determine whether increased generation of vascular superoxide anion (*O2-) contributes to blood pressure elevation by influencing vascular function and structure in severely hypertensive rats. Sixteen-week-old stroke-prone spontaneously hypertensive rats (SHRSP) (n = 12) were randomly divided into two groups to receive the superoxide dismutase mimetic, tempol (4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl) (1 mmol/L in drinking water) or tap water. Both groups were fed a high-salt diet (4% NaCl). Systolic blood pressure (SBP) was measured weekly for 6 weeks by the tail-cuff method. Rats were killed, and vascular structure (media:lumen ratio) and endothelial function (acetylcholine [Ach]-induced vasodilation) were assessed in small mesenteric arteries mounted as pressurized preparations. Vascular *O2- concentration was measured by lucigenin (5 micromol/L) chemiluminescence. Plasma total antioxidant status was assessed spectrophotometrically. The SBP increased significantly (P < .01) in the control group, whereas progression of hypertension was prevented in the tempol-treated group. Tempol reduced (P < .01) the media:lumen ratio (7.2%+/-0.01%) compared with that in controls (12.0%+/-0.01%). Maximal Ach-induced dilation was altered in control rats (40%+/-9%) but was not influenced by tempol (57%+/-17%). Vascular *O2- concentration was lower (P < .01) and plasma total antioxidant concentration was higher (P < .05) in the treated group compared with the control. In conclusion, tempol prevents progression of hypertension. These processes are associated with attenuated vascular remodeling, decreased vascular *O2- concentration, and increased antioxidant status. Our data suggest that oxidative stress plays an important role in vascular damage associated with severe hypertension in salt-loaded SHRSP.
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PMID:Chronic treatment with a superoxide dismutase mimetic prevents vascular remodeling and progression of hypertension in salt-loaded stroke-prone spontaneously hypertensive rats. 1182 65

Renin-angiotensin-aldosterone system blockade has been shown to protect against renal damage in salt-supplemented, stroke-prone spontaneously hypertensive rats (SHRsp). Based on intermittent tail-cuff blood pressure (BP) measurements, it has been claimed that such protection is BP-independent and mediated by a blockade of the direct tissue-damaging effects of angiotensin and/or aldosterone. BP radiotelemetry was performed for 8 weeks in approximately 10-week-old male SHRsp who received a standard diet and either tap water (n=10) or 1% NaCl to drink. Saline-drinking SHRsp were either left untreated (n=12), received enalapril (50 mg/L) in drinking fluid (n=9), or had subcutaneous implantation of time-release 200-mg pellets of aldactone (n=10). The average systolic BP (mean+/-SEM) during the final 3 weeks was significantly higher (P<0.05) in untreated saline-drinking (215+/-6 mm Hg) SHRsp but not aldactone-treated (198+/-4 mm Hg) or enalapril-treated treated SHRsp (173+/-1 mm Hg), as compared with tap water-drinking SHRsp (197+/-3 mm Hg). Histological renal damage scores at 8 weeks paralleled the BP in all groups, with an excellent correlation (r=0.8, P<0.001, n=41). Moreover, a renal damage score of >5 was only observed in SHRsp whose average systolic BP during the final 3 weeks exceeded 200 mm Hg, indicating a threshold relation with BP. These data show that protection by renin-angiotensin-aldosterone system blockade in this model is BP-dependent and mediated by preventing the severe increases in BP seen in untreated salt-supplemented SHRsp and further underscore the limitations of interpretations based on conventional tail-cuff BP measurements.
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PMID:Renoprotection by ACE inhibition or aldosterone blockade is blood pressure-dependent. 1257 79

This study was designed to show the effects of onion on blood pressure in N(G)-nitro-L-arginine methyl ester (L-NAME) induced-hypertensive rats and stroke prone spontaneously hypertensive rats (SHRSP) using dried onion at 5% in their diets. For the experiment with L-NAME induced-hypertensive rats, male 6-weeks-old Sprague-Dawley rats were given tap water containing L-NAME to deliver 50 mg/kg BW/day. In this experiment, we found distinct antihypertensive effects of onion on the L-NAME induced-hypertensive rats and the SHRSP. Dietary onion decreased the thiobarbituric acid reactive substances (TBARS) in plasma in these hypertensive rats. Also, onion increased the nitrate/nitrite (products of nitric oxide (NO)) excreted in urine and the NO synthase (NOS) activity in the kidneys in SHRSP. These results suggested that the increased NO caused by the greater NOS activity, and additionally by the increased saving of NO by the antioxidative activity of onion, was one of the cause of the antihypertensive effect of onion in SHRSP. In the L-NAME induced hypertensive rats, onion did not significantly block the inhibition of NOS activity by L-NAME, and decreased nitrate/nitrite excretion in urine was not restored. The mechanism of the antihypertensive effect of onion probably involves increased saving of NO by antioxidative activity of onion in L-NAME induced-hypertensive rats.
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PMID:Antihypertensive effects of onion on NO synthase inhibitor-induced hypertensive rats and spontaneously hypertensive rats. 1284 58

Efforts to harness in situ skeletal muscle for circulatory support have been extensive, but implants designed to tap this power source have yet to meet the strict performance standards incumbent upon such devices. A fourth generation muscle energy converter (MEC4) is described that represents a significant departure from previous hydraulic muscle pump designs, all of which have assumed a long cylindrical profile. The MEC4, in contrast, features a puck shaped metallic bellows oriented so that its end fittings lie parallel to the chest wall. The fixed end is centered over a fluid port that passes into the thoracic cavity across one resected rib. The opposite end of the bellows supports a roller bearing that moves beneath a linear cam fixed to a reciprocating shaft. The shaft exits the housing through a spring loaded seal and is attached to a sintered anchor pad for muscle tendon fixation. This configuration was chosen to improve bellows durability, lower device profile, and reduce tissue encumbrance to actuator recoil. Bench tests show that modest actuation forces can effect full actuator displacement in 0.25 seconds against high pressure loads, transmitting up to 0.9 J/stroke at 60% efficiency. In vitro tests also confirm that key device performance parameters can be computed from pressure readings transmitted via radiotelemetry, clearing the way for long-term implant studies in conscious animals.
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PMID:Capturing in situ skeletal muscle power for circulatory support: a new approach to device design. 1291 95

Oxidative stress was reported to be involved not only in cardiovascular diseases, but also in hypertension. Epidemiologic studies indicated that tea consumption slightly reduces blood pressure. We conducted two studies to determine whether black and green tea can lower blood pressure (BP) in stroke-prone spontaneously hypertensive rats (SHRSP). Male SHRSP (n=15) were allowed to recover for 2 wk after a transmitter for measuring BP was implanted in the peritoneal cavity. The rats were divided into three groups: the control group consumed tap water (30 mL/d); the black tea polyphenol group (BTP) consumed water containing 3.5 g/L thearubigins, 0.6 g/L theaflavins, 0.5 g/L flavonols and 0.4 g/L catechins; and the green tea polyphenol group (GTP) consumed water containing 3.5 g/L catechins, 0.5 g/L flavonols and 1 g/L polymetric flavonoids. The telemetry system was used to measure BP, which were recorded continuously every 5 min for 24 h. During the daytime, systolic and diastolic BP were significantly lower in the BTP and GTP groups than in the controls. Protein expressions of catalase and phosphorylated myosin light chain (MLC-p) were measured in the aorta by Western blotting. GTP significantly increased catalase expression, and BTP and GTP significantly decreased MLC-p expression in the aorta. These data demonstrate that both black and green tea polyphenols attenuate blood pressure increases through their antioxidant properties in SHRSP. Furthermore, because the amounts of polyphenols used in this experiment correspond to those in approximately 1 L of tea, the regular consumption of black and green tea may also provide some protection against hypertension in humans.
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PMID:Black and green tea polyphenols attenuate blood pressure increases in stroke-prone spontaneously hypertensive rats. 1470 90

It has been proposed recently that a deficit in keeping track of spatial locations may contribute to the severity of unilateral neglect in some right hemisphere stroke patients. However, performance on traditional spatial working memory (SWM) tasks (e.g. Corsi blocks) might be confounded by failure to encode leftward locations, rather than a true deficit of maintaining locations in SWM. Here we introduced new procedures for circumventing this to measure SWM capacity in neglect. In a first experiment, 20 right hemisphere stroke patients (10 with and 10 without neglect) were tested on a computerized vertical variant of the Corsi task. Sequences of spatial locations in a vertical column were displayed and participants had to tap out the remembered sequence on a touchscreen. Patients with left neglect were impaired on this vertical SWM task compared with all control groups. However, poor performance on this task (as for Corsi blocks) might involve impaired memory for stimulus sequence, or poor visuomotor control of manual responding, rather than reduced SWM capacity per se. A second experiment therefore employed a purer measure of vertical SWM. After the displayed sequence, a single location was now probed visually, with observers judging verbally (yes/no) if it had been in the preceding sequence. Hence order no longer mattered, and no spatial motor response was required. Again, the neglect group was impaired relative to all others, now with very little overlap between the performances of individual neglect patients versus individuals in control groups. Poor performance on the second task, which provides a purer measure of SWM capacity, correlated with severity of left neglect on cancellation tasks (but not on line bisection), consistent with recent proposals that SWM deficits can exacerbate left neglect on visual search tasks when present conjointly. Lesion anatomy indicated that neglect patients with a SWM deficit were most likely to have damage to parietal white matter, plus, in the second experiment, to the insula also. These findings demonstrate that an impairment in SWM capacity can contribute to the neglect syndrome in patients with stroke involving regions within the right parietal lobe and insula.
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PMID:Spatial working memory capacity in unilateral neglect. 1564 22

Although it is now understood that trained skeletal muscle can generate enough steady-state power to provide significant circulatory support, there are currently no means by which to tap this endogenous energy source to aid the failing heart. To that end, an implantable muscle energy converter (MEC) has been constructed and its function has been improved to optimize durability, anatomic fit, and mechanical efficiency. Bench tests show that MEC transmission losses average less than 10% of total work input and that about 85% of this muscle power is successfully transferred to the working fluid of the pump. Results from canine implant trials confirm excellent biocompatibility and demonstrate that contractile work of the latissimus dorsi muscle-measured to 290 mJ/stroke in one dog-can be transmitted within the body at levels consistent with cardiac assist requirements. These findings suggest that muscle-powered cardiac assist devices are feasible and that efforts to further develop this technology are warranted.
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PMID:Improved mechanism for capturing muscle power for circulatory support. 1614 10

The central nervous system (CNS) is, after the peripheral nervous system, the second most frequently affected organ in mitochondrial disorders (MCDs). CNS involvement in MCDs is clinically heterogeneous, manifesting as epilepsy, stroke-like episodes, migraine, ataxia, spasticity, extrapyramidal abnormalities, bulbar dysfunction, psychiatric abnormalities, neuropsychological deficits, or hypophysial abnormalities. CNS involvement is found in syndromic and non-syndromic MCDs. Syndromic MCDs with CNS involvement include mitochondrial encephalomyopathy, lactacidosis, stroke-like episodes syndrome, myoclonic epilepsy and ragged red fibers syndrome, mitochondrial neuro-gastrointestinal encephalomyopathy syndrome, neurogenic muscle weakness, ataxia, and retinitis pigmentosa syndrome, mitochondrial depletion syndrome, Kearns-Sayre syndrome, and Leigh syndrome, Leber's hereditary optic neuropathy, Friedreich's ataxia, and multiple systemic lipomatosis. As CNS involvement is often subclinical, the CNS including the spinal cord should be investigated even in the absence of overt clinical CNS manifestations. CNS investigations comprise the history, clinical neurological examination, neuropsychological tests, electroencephalogram, cerebral computed tomography scan, and magnetic resonance imaging. A spinal tap is indicated if there is episodic or permanent impaired consciousness or in case of cognitive decline. More sophisticated methods are required if the CNS is solely affected. Treatment of CNS manifestations in MCDs is symptomatic and focused on epilepsy, headache, lactacidosis, impaired consciousness, confusion, spasticity, extrapyramidal abnormalities, or depression. Valproate, carbamazepine, corticosteroids, acetyl salicylic acid, local and volatile anesthetics should be applied with caution. Avoiding certain drugs is often more beneficial than application of established, apparently indicated drugs.
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PMID:Central nervous system manifestations of mitochondrial disorders. 1694 41

Studies were carried out on stroke-prone spontaneously hypertensive rats (SHRSP) to determine the cardiovascular effects of a traditional medicine extracted from the fungus Fuscoporia obliqua. The rats received either a hot-water extract of Fuscoporia or tap water for 60 days. Heart rate and blood pressure were measured in the tail and venous blood was analyzed for glycated hemoglobin (HbA1c) and leukocyte number. Sections of the left ventricular wall were stained for alkaline phosphatase and dipeptidylpeptidase IV to distinguish the arteriolar from the venular portions of the capillaries. Capillary to myocyte ratio (C:M ratio) was also measured. Treated rats showed a significant decrease in arterial pressure, a mild increase in leukocyte and a trend towards a decrease in HbA1c. There was a trend towards an increase in total capillary density in the subendomyocardium accompanied by a decrease in the arteriolar capillary portions. C:M ratio showed no clear change. It is concluded that the hot-water extract of Fuscoporia has beneficial effects on cardiovascular function, hematological status and probably immunological function in SHRSP.
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PMID:Cardiovascular effects produced by a traditional fungal medicine, Fuscoporia obliqua extract, and microvessels in the left ventricular wall of stroke-prone spontaneously hypertensive rat (SHRSP). 1714 48

Annually, approximately 30,000 people suffer from aneurysmal subarachnoid hemorrhage (SAH) in the United States. In an estimated 5% of these patients, the hemorrhage is difficult to diagnose using conventional methods. Clinicians must rely upon a combination of clinical history, Computerized Tomography (CT) scan evidence and lumbar puncture results to diagnose and differentiate SAH from a traumatic spinal tap (blood in the spinal fluid due to the procedure). Here we describe an algorithm based development of an analytic methodology using visible spectroscopy to reliably quantify bilirubin in hemorrhagic spinal fluid. The analysis, which may be useful for diagnoses concerning hemorrhagic stroke, is based on the detection of bilirubin, and concomitant blood products produced within the Cerebral Spinal Fluid (CSF) following SAH. The algorithm quantifies bilirubin (0.3 to 10 mg/dL) from the resultant absorption spectrum. A model is developed from standard visible spectroscopic absorption curves of bilirubin and hemoglobin by applying traditional Beer's Law principles. The model is coupled to a modified partial least square analysis and control theory concept where the bilirubin is the "signal" and is masked by hemoglobin "noise." This paper describes the computational methods, sensitivity and utility of a system to quantify bilirubin in CSF like solutions containing hemoglobin and bilirubin over 0.5 g/dL-10 g/dL of hemoglobin concentrations.
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PMID:Spectrophotometric quantification of bilirubin in hemorrhagic spinal fluid using an innovative algorithm. 1726 20


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