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)

Ketanserin, a selective serotonergic (5-HT2) antagonist, also has affinity for alpha 1-adrenoceptors. It is not clear whether the hypotensive mechanism of ketanserin is due to its antagonistic action to 5-HT2 receptor or to its affinity for alpha 1 adrenoceptors. The hypotensive mechanism of ketanserin was studied in both stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar Kyoto rats (WKY). Anesthetized rats were used (alpha-chloralose + urethane, i.p.). Up to 3 ml of blood was drawn from each rat for analysis. Plasma norepinephrine (NE) was determined by radioenzymatic assay. Plasma serotonin (5-HT) was determined by HPLC-ECD. Adrenal nerve discharges were counted by a digital pulse counter. Ketanserin (0.5 mg/kg, 5.0 mg/kg, i.v.) produced a dose-dependent reduction of mean arterial pressure (MAP) in both SHRSP and WKY. MAP of SHRSP decreased significantly as compared with WKY. Both plasma NE and 5-HT showed a tendency to increase during ketanserin administration (5.0 mg/kg, i.v.). Ketanserin significantly antagonized the BP response induced by exogenously injected 5-HT (30 micrograms/kg) and NE (10 micrograms/kg). Adrenal nerve activity was reduced in parallel with the decrease in BP and HR. These findings suggest that ketanserin produced a decrease in BP via both peripheral and central action in rats.
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PMID:[Effect of ketanserin on blood pressure in rats]. 241 29

Rat and human plasma catecholamines were measured simultaneously by HPLC-THI, HPLC-ECD and REA, and the three methods were compared. An attempt was also made to determine the factors affecting the estimated value of plasma catecholamine concentration. Our study showed that: Sensitivity and reproducibility to norepinephrine and epinephrine were identical in all three methods. One advantage of the REA method is that comparatively smaller sample volumes are required to produce similar results. Plasma dopamine concentration in peripheral blood samples was determined by the HPLC-ECD rather than the HPLC-THI method. Withdrawal of 5 ml of blood produced a significant increase in norepinephrine, epinephrine and dopamine in rat plasma. The catecholamine concentration in these cases was determined by the REA method. Plasma norepinephrine concentration did not increase with age in Wistar Kyoto rats. However, plasma norepinephrine concentration increased significantly with age in stroke-prone spontaneously hypertensive rats (SHRSP). Plasma norepinephrine concentration in male SHRSP was greater than that in female SHRSP. SHRSP-plasma norepinephrine concentrations rose in parallel to increases in blood pressure. The plasma norepinephrine concentration in SHRSP with cerebral hemorrhage rose significantly as compared with the plasma norepinephrine levels in SHRSP without cerebral bleeding. Because each method of determination of plasma catecholamine concentration has both merits and demerits, selection should be determined by sample size and amount of catecholamines in the plasma samples. Factors affecting the estimated value of plasma catecholamine concentration should be taken into consideration.
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PMID:[The factors affecting plasma catecholamines concentration in rats and man]. 671 49

Brain imaging is performed using radiopharmaceuticals by single photon emission computed tomography (SPECT) and positron emission tomography (PET). SPECT and PET radiopharmaceuticals are classified according to blood-brain-barrier permeability, cerebral perfusion and metabolism receptor-binding, and antigen-antibody binding. The blood-brain-barrier (BBB) SPECT agents, such as 99mTcO4-, [99mTc]DTPA, 201TI and [67Ga]citrate are excluded by normal brain cells, but enter into tumor cells because of altered BBB. These agents were used in the earlier period for the detection of brain tumors. SPECT perfusion agents such as [123I]IMP, [99mTc]HMPAO, [99mTc]ECD are lipophilic agents and therefore, diffuse into the normal brain. These tracers have been successfully used to detect various cerebrovascular diseases such as stroke, Parkinson disease, Huntington's disease, epilepsy, dementia, and psychiatric disorders. Xenon-133 and radiolabeled microspheres have been used for the measurement of cerebral blood flow (CBF). Important receptor-binding SPECT radiopharmaceuticals include [123I]QNE, [123I]IBZM, and [123I]iomazenil. These tracers bind to specific receptors in the brain, thus displaying their distribution in various receptor-related cerebral diseases. Radioiodinated monoclonal antibodies were used for the detection of brain tumors. PET radiopharmaceuticals for brain imaging are commonly labeled with positron-emitters such as 11C, 13N, 15O, and 18F, although other radionuclides such as 82Rb, 62Cu and 68Ga also were used. The brain uptake of [13N]glutamate, [68Ga]EDTA and [82Rb]RbCl depends on the BBB permeability, but these are rarely used for brain imaging. Several cerebral perfusion agents have been introduced, of which [15O]water, [13N]ammonia, and [15O]butanol have been used more frequently. Regional CBF has been quantitated by using these tracers in normal and different cerebral disease states. Other perfusion agents include [15O]O2, [11C]CO, [11C]CO2, [18F]fluoromethane, [15O]O2, [11C]butanol, and [62Cu]PTSM. Among the PET cerebral metabolic agents, [18F]fluorodeoxyglucose (FDG) is most commonly used to detect metabolic abnormalities in the brain. Various brain tumors have been graded by [18F]FDG PET. This technique was used to detect epileptic foci by showing increased uptake in the foci during the ictal period and decreased uptake in the interictal period. Differentiation between recurrent tumors and radiation necrosis and the detection of Alzheimer's disease have been made successfully by [18F]FDG PET. Other PET metabolic agents such as [11C]deoxyglucose, and [11C]methylmethionine have drawn attention in the detection of brain tumors. [18F]fluorodopa is a cerebral neurotransmitter agent, which has been found very useful in the detection of Parkinson disease that shows reduced uptake of the tracer in the striatum of the brain.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Radiopharmaceuticals for brain imaging. 781 3

Focal hyperaemia is a fairly common phenomenon in the subacute phase of an ischaemic stroke. This has rarely been reported with iodine-123 iodoamphetamine (IMP) and has never been identified using technetium-99m bicisate (99mTc-ECD). In this report, we present the case of a patient suffering from a left cerebral posterior stroke. 123I-IMP single-photon emission tomography (SPET) images showed a large area of significantly increased IMP activity located in the left occipital region whereas 99mTc-bicisate SPET displayed hypoactivity in the same area.
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PMID:Non-matched images with 123I-IMP and 99mTc-bicisate single-photon emission tomography in the demonstration of focal hyperaemia during the subacute phase of an ischaemic stroke. 820 Mar 94

To evaluate the cerebral distribution of 99mTc-ethyl cysteinate dimer (99mTc-ECD) at blood flow levels beyond the normal range, we investigated postischemic reperfusion and acetazolamide (Diamox) activation test in stroke patients. The postischemic reperfusion was studied in 10 patients who showed a postischemic hyperperfusion area on other single photon emission computed tomography (SPECT) studies using N-isopropyl-rho-[123I]iodoamphetamine ([123I]IMP), 99mTc-hexamethyl propyleneamine oxime (99mTc-HMPAO), or 133Xe. 99mTc-ECD SPECT demonstrated a hyperactive area in one case, an isoactive area in four, and a hypoactive area in five. Correlations with CT findings revealed hyperactive areas without any abnormality, isoactive areas with perifocal rim, perifocal edema, or diffuse cerebral edema, and hypoactive areas with an infarct core. The Diamox activation test was studied in eight other patients with atherothrombotic stroke, and a limitation in vasodilative capacity was classified into three grades: Gr. 0 (none to minimal), Gr. I (mild), and Gr. II (moderate). [123I]IMP SPECT showed Gr. II and limitation in all eight cases. However, 99mTc-ECD showed Gr. II in three cases and Gr. I in five, and 99mTc-HMPAO revealed Gr. II in two cases, Gr. I in three, and Gr. 0 in three. We suggest that a lack of retention of 99mTc-ECD in a postischemic reperfusion area indicates the severity of the initial brain damage. Although the limitation in vasodilative capacity under Diamox-activated conditions was underestimated using 99mTc-labeled CBF tracers as compared with [123I]IMP, a retention of 99mTc-ECD in the unaffected area with an increased CBF under Diamox activation could be relatively superior to 99mTc-HMPAO.
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PMID:Assessment of postischemic reperfusion and diamox activation test in stroke using 99mTc-ECD SPECT. 826 72

99mTc-bicisate (99mTc-ECD) is a new brain perfusion imaging agent formulated from a radiochemically stable kit (Neurolite). A multicenter trial was conducted to determine the sensitivity and specificity of single photon emission computed tomography (SPECT) imaging with 99mTc-bicisate in the localization of ischemic stroke; 170 subjects were enrolled, 128 patients with stroke and 42 controls. Imaging results from 148 subjects (107 stroke patients and 41 controls) were considered evaluable. In the evaluable subjects, SPECT brain imaging with 99mTc-bicisate (21.0 +/- 2.5 mCi) was interpreted without clinical information and was compared with a final assessment using all clinical, diagnostic, and laboratory procedures except the 99mTc-bicisate SPECT results. 99mTc-bicisate was safe and well-tolerated. SPECT imaging with 99mTc-bicisate demonstrated a specificity of 98% and a sensitivity of 86% for localization of strokes (kappa, 0.75; 95% confidence interval, 0.64-0.86). Results were unchanged over time and were similar for all stroke mechanisms except for lacunar disease (sensitivity, 58%). In a secondary analysis, a normal image or small, deep (e.g., subcortical) perfusion defect was highly predictive of a lacunar mechanism. Defects involving the cortical surface were strongly associated with nonlacunar mechanisms. SPECT imaging with 99mTc-bicisate is a sensitive marker in the localization of perfusion defects associated with ischemic stroke and may assist in the determination of the underlying mechanism of a stroke.
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PMID:The role of single photon emission computed tomography brain imaging with 99mTc-bicisate in the localization and definition of mechanism of ischemic stroke. 826 77

To evaluate the cerebral pharmacokinetics of 99mTc-ethyl cysteinate dimer (99mTc-ECD) at blood flow levels beyond the normal range, we investigated "luxury perfusion" in subacute stroke, ictal hyperperfusion in epilepsy and post-decompressive hyperemia in head trauma. All 7 patients showed a hyperactive area on SPECT studies using 99mTc-HM-PAO. 99mTc-ECD static image demonstrated a hyperactive area in both epilepsy and head trauma, and a hypoactive area in "luxury perfusion." On the dynamic SPECT of 99mTc-ECD in both epilepsy and head trauma, brain distribution of the tracer was determined within 2 min. postinjection and remained stable for up to 1 hour; however, "luxury perfusion" area showed a change from initial hyperactivity to late hypoactivity with the passage of time. The time activity curve in "luxury perfusion" area demonstrated a steep decrease of counts/pixel for up to 4-5 minutes postinjection, and a moderate decrease in the following phase. The early wash-out mechanism of 99mTc-ECD from "luxury perfusion" area can be described by a biexponential function including an initial steep decrease representing the rapid loss of the lipophilic complexes which were not metabolized in injured brain tissue.
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PMID:[99mTc-ECD dynamic SPECT in "luxury perfusion" of subacute stroke]. 855 92

Among several brain radiopharmaceuticals for SPECT imaging, 99mTc complexes of HMPAO and ECD are the most widely used. They are considered to be equal in their capacity to reflect regional cerebral blood flow; but discrepancies between HMPAO and ECD brain uptake have been reported in stroke patients. This paper reports our observations regarding discrepancies between HMPAO and ECD SPECT in 14 of 23 patients with suspected brain tumors or presumed metabolic cerebral abnormalities. We obtained similar conflicting results, namely focal HMPAO hyperactivities and isoactive ECD SPECT. The majority of these discrepancies were found in patients with brain tumors (10 of 13 patients), while only 4 of the 10 remaining patients with nontumoral process showed similar discrepant results. The physiopathology behind these observations is discussed here, and it is likely to be related to the specific response to cellular metabolic disorders rather than to perfusion disturbances.
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PMID:Discrepancies between HMPAO and ECD SPECT imaging in brain tumors. 909 8

We describe a 25 year old woman diagnosed with MELAS during an acute stroke-like episode. Global aphasia, migraine-like headaches and hemi-anopsia were her main clinical features. MR imaging revealed extensive cortical and subcortical left hemispheric signal abnormalities. [Tc-99m]ECD SPECT scanning revealed crossed cerebrocerebellar diaschisis. Aphasia in the absence of gross hemiparesis can be related to cross-cerebellar diaschisis in MELAS.
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PMID:Crossed cerebro-cellular diaschisis in a patients with melas with aphasia but without hemiparesis. 963 34

The aim of this study was to define the accuracy of 99mTc-ethyl cysteinate dimer-single photon emission computed tomography (99mTc-ECD-SPECT) in distinguishing transient ischemic attack from completed ischemic stroke at early stages after the onset of symptoms. In a prospective study we examined 82 patients within 6 hours after the onset of symptoms (neurologic deficit caused by middle cerebral artery ischemia) using both 99mTc-ECD-SPECT and computed tomography (CT). The follow-up was based on Scandinavian Stroke Scale (SSS) 24 hours and 5-7 days, as well as on CT 7 days, after the event. SPECT evaluation was performed both visually and using semiquantitative region-of-interest (ROI) analysis. According to visual SPECT analysis, on admission 59 of 82 patients had activity deficits in the symptomatic hemisphere. After 7 days, all these patients had neurologic symptoms (SSS 28 +/- 12 points), caused by a cerebral infarction as evidenced with CT. Twenty-three of 82 patients displayed no early activity deficit despite clinical symptoms. None of these patients had neurologic symptoms after 7 days (indicating transient ischemic attack or prolonged reversible ischemic neurologic deficit). In the semiquantitative SPECT analysis, all patients had abnormal count densities in the respective ROI (activity < 90% compared with the contralateral side). All patients with transient ischemia (n = 23) had count rate densities more than 70% of the respective contralateral ROI, whereas all patients with subsequent infarction (n = 59) had values < 70%. Use of 99mTc-ECD-SPECT allows transient ischemia to be distinguished from ischemic infarction using relative regional activity thresholds within the first 6 hours after onset of symptoms.
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PMID:Differentiation between transient ischemic attack and ischemic stroke within the first six hours after onset of symptoms by using 99mTc-ECD-SPECT. 970 54


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