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

The possible role of displaced neurotransmitter acetylcholine (ACHh) in dysautoregulation was examined after experimental regional cerebral infarction was produced by occluding the middle cerebral artery (MCA) in babons. Regional cerebral blood flow (rCBF) was measured after intracarotid injection of 133Xenon using the gamma camera. Autoregulation was tested with metaraminol or angiotensin infusion and the autoregulation index (A.I.) was calculated. Acetylcholinesterase (ACHhE) was measured in brain tissue of noninfarcted and infarcted hemispheres. Cerebral arteriovenous (A-V) differences for cholinesterase (ChE) were also measured. Regional dysautoregulation was found in infarcted gray matter and correlated with increased AChE levels in the same zones of cortex and basal ganglia. The time course of onset of dysautoregulation correlated with increased ChE uptake by the brain. Intravenous infusion of the cholinergic neurotransmitter blocker, scopolamine, restored autoregulation to the ischemic zones. Autoregulation appears to be a myogenic reflex, influenced by neurogenic and metabolic mechanisms.
Stroke
PMID:Disordered cholinergic neurotransmission and dysautoregulation after acute cerebral infarction. 16 7

Phosphamidon (2-chloro-3-(diethylamino)-1-methyl-3-oxopropanyldimethyl phosphate) is widely used in agriculture as an organophosphate insecticide. It is a water-soluble cholinesterase inhibitor whose estimated rat LD50 is 9.2 mg/kg, ip. Mechanical and electrophysiologic direct effects of phosphamidon were studied in an isolated working rat heart model. Phosphamidon caused a positive inotropic effect, as indicated by increased maximum time derivative of left ventricular pressure and increased cardiac output. Stroke work and total pressure-volume area increased in a dose-dependent manner following perfusion with phosphamidon. Phosphamidon had in this preparation a biphasic effect on heart rate: at 10(-6) M concentration, heart rate increased, but at higher concentrations (10(-4)-10(-3) M) heart rate decreased significantly. High concentrations of phosphamidon caused a significant prolongation of the Q-T interval. We conclude that phosphamidon has potent cardiotoxic effects, both mechanical and electrophysiologic, on the isolated rat heart.
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PMID:Direct effects of phosphamidon on isolated working rat heart electrical and mechanical function. 194 11

Many of the drugs used in anesthesia and intensive care may cause blockade of the central cholinergic neurotransmission. Acetylcholine is of significance in modulation of the interaction among most other central transmitters. The clinical picture of the central cholinergic blockade, known as the central anticholinergic syndrome (CAS), is identical with the central symptoms of atropine intoxication. This behaviour consists of agitation including seizures, restlessness, hallucinations, disorientation or signs of depression such as stupor, coma and respiratory depression. Such disturbances may be induced by opiates, benzodiazepines, phenothiazines, butyrophenones, ketamine, etomidate, propofol, nitrous oxide, and halogenated inhalation anesthetics as well as by H2-blocking agents such as cimetidine. There is an individual predisposition for CAS--but unpredictable from laboratory findings or other signs. Reports of postanesthetic occurrence of the CAS requiring treatment are not unanimous, varying between 1 and 40%. Differential diagnosis of the CAS includes disorders of glucose and electrolyte metabolism, severe hormonal imbalance, respiratory disorders (hypoxia, hypercarbia), hypothermia, hyperthermia and neuropsychiatric diseases (cerebral hypoxia, stroke, catatony, acute psychosis). The CAS may considerably impair the postanesthetic period especially when agitation is prevalent, which may endanger the patient or the surgical results. The diagnosis is confirmed ex iuvantibus by the sudden increase in the acetylcholine level in the brain. This is achieved with physostigmine, a cholinesterase inhibitor able to easily cross the blood-brain barrier. Its peripheral muscarinic effects are minimal. Postanesthetic CAS can be prevented by administration of physostigmine during the anesthesia procedure. During intensive care (IC), agitated forms of CAS may occur in patients undergoing mechanical ventilation, particularly during prolonged high-dose sedation. Artificial ventilation of such patients becomes very difficult and muscle relaxation may be necessary. In these cases of IC-CAS, physostigmine is of value and has proven beneficial during weaning from mechanical ventilation. Dealing with the CAS for more than a decade has improved knowledge of the central cholinergic transmission. For example, it can be said that CAS occurs alongside general anesthesia, being no more than a frequent side-effect. Furthermore, acetylcholine is involved in nociception through the endorphinergic and the serotoninergic systems. There is a close relation between the central cholinergic transmission and actions of nitrous oxide. Moreover, cholinergic transmission is involved in withdrawal from (among others) alcohol, opiates, hallucinogens and nitrous oxide. In some intoxications with psychoactive agents, physostigmine is useful for reversal of the central nervous symptoms of the acute intoxication itself. In addition it can be used for prevention of some withdrawal states. In
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PMID:Central anticholinergic syndrome (CAS) in anesthesia and intensive care. 268 49

Three dose levels of pyridostigmine (0.5, 2, and 5 mg/kg) were given iv to dogs anesthetized with sodium pentobarbital. Hemodynamic measurements made were cardiac output, blood pressure, left ventricular dP/dT, and heart rate. Pulmonary function data obtained were airway resistance, respiratory rate, and tidal volume. Activity of blood cholinesterase was also measured. Increasing doses of pyridostigmine promptly and progressively lowered the acetylcholinesterase activity of blood to a minimum of 40% of control at the 5 mg/kg dose. Airway resistance was most sensitive to the drug. Resistance increased significantly with 2 mg/kg, and the 5 mg/kg dose resulted in more than a 10-fold increase, which persisted for more than 2 hr. Tidal volume was decreased and minute volume was increased due to an increase in respiratory rate. With the higher doses, heart rate decreased and stroke volume rose sufficiently to compensate so that cardiac output was unchanged. The lowest dose produced minimal effects on both cardiovascular and respiratory systems, and since this dose is greater than that proposed for organophosphate poisoning in humans, it seems likely that this drug would not cause important effects in normal humans when used as a protective agent.
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PMID:Interactions of pyridostigmine with cardiopulmonary systems and their relationships to plasma cholinesterase activity. 273 58

Twenty-one patients with acute brain infarction, 8 with transient ischemic attack and 20 controls were investigated for lumbar cerebrospinal fluid (CSF) monoamine metabolites and cholinesterases. The diseased patients were lumbar punctured on 2 occasions, mean Days 1 (0-3) and 5 (3-9) after debut of symptoms. Monoamine concentrations were determined by reverse phase liquid chromatography with electrochemical detection and the cholinergic enzymes were measured photometrically. Increased concentrations of 3-methoxytyramine (3-MT), homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HI-AA) and increased activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in lumbar cerebrospinal fluid was found in patients with acute brain infarction when compared to control values, while the levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) were not altered. No change of any neurotransmitter metabolite concentration/enzyme activity were found between Day 1 and Day 5 in the diseased patients. These data suggest an increased release of these neurotransmitter markers from necrotic brain areas into the cerebrospinal fluid and/or altered barriers between blood, brain and CSF and/or a dysfunction of the arachnoid villi to clear substances from the CSF. We therefore concluded that CSF neurotransmitters may be useful as specific brain markers in acute stroke.
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PMID:Increased monoamine metabolite concentrations and cholinesterase activities in cerebrospinal fluid of patients with acute stroke. 343 5

Cerebral cortical ischemia was induced in anesthetized rats by occlusion of the middle cerebral artery (MCA). Cerebral blood flow (CBF) was measured with the H2 clearance technique in the center and periphery of the ischemic territory. A decrease of CBF to about 50% of pre-occlusion values was observed in both areas. Administration of Physostigmine, a cholinesterase inhibitor, at a dose of 0.15 mg/Kg by intravenous route, induced an increase of CBF in the ischemic cortex. This change in CBF reached 120% of pre-occlusion level in the periphery and 80% of pre-occlusion value in the center of the area of distribution of the occluded artery. Although Physostigmine induced an increase in arterial blood pressure, the cerebral hyperemia observed both in normal and ischemic cortex could still be demonstrated after blockade of the pressor effect by bleeding or Phentolamine administration.
Stroke
PMID:Physostigmine induced reversal of ischemia following acute middle cerebral artery occlusion in the rat. 376 45

Antagonism of neuromuscular block using cholinesterase inhibitors and atropine is charged with several risks, which are at least partly caused by pharmacological characteristics of the anticholinergic drugs, e.g. short duration of action causing secondary bradycardia. Compared to atropine, ipratropium bromide, a new anticholinergic drug, is--due to its quarternary ammonium compound--characterized by longer duration of action. In contrast to atropine, this substance does not penetrate the blood-brain and placental barrier. Our present study was designed to compare the haemodynamic effects of both substances, using invasive monitoring, during antagonism of neuromuscular block with pyridostigmine. In contrast to atropine, ipratropium bromide induced a higher degree of initial tachycardia but did not allow secondary reduction of heart rate by rebound vagal stimulation. While cardiac output was almost constant, ipratropium bromide caused changes in stroke volume, which were due to alterations in heart rate. There were no clinically relevant changes of the other haemodynamic parameters. Cardiac arrhythmia were observed more often after administration of atropine and were of longer duration. In conclusion, ipratropium bromide is a useful alternative to atropine in patients with pre existing low heart rate and bradyarrhythmia.
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PMID:[Hemodynamic effects in antagonism of neuromuscular blockage: atropine-pyridostigmine versus ipratropium bromide-pyridostigmine]. 623 62

In order to assess the thyroid function of patients with nonthyroidal illness, 292 patients with nonthyroidal illness were employed in the present study. These patients were then subdivided into 6 groups according to their original illness. The groups consisted of patients with malignant illnesses (19 males and 10 females; mean age of 59.7 yr.), with chronic hepatitis (14 males and 8 females; mean age of 55.2 yr.), with liver cirrhosis (5 males and 6 females, mean age of 60.4 yr.), with uremia who had been receiving constant hemodialysis 2 approximately 3 times per week (52 males and 38 females; mean age of 48.1 yr.), with diabetes mellitus (50 males and 43 females; mean age of 52.3 yr.) and with cerebrovascular accident (21 males and 26 females; mean age of 74.9 yr.). In addition, 34 healthy persons (15 males and 19 females; mean age of 41.6 yr.) were also employed as controls. Because the differences between mean ages in these groups were significant, the relationship between age and thyroid function was examined. Significant positive correlations between age and total thyroxine (TT4) (r = 0.19; p less than 0.01), and reverse triiodothyronine (rT3) (r = 0.175; p less than 0.01) were found. A negative correlation was also found between age and total triiodothyronine (TT3) (r = 0.231; p less than 0.01). The serum levels of rT3 were elevated in patients with neoplasma and liver cirrhosis but significantly low in patients with uremia. These characteristic findings were correlated with the severity of each original disease such as % motarity, serum levels of cholinesterase, blood urea nitrogens and the blood sugar control in the diabetics. In these circumstances, multiple correlation analyses were performed in order to assess whether there might exist a negative feedback mechanism between thyrotropin and FT4/FT3. The highest partial correlation coefficient was obtained between thyrotropin and FT4. It might, therefore, be concluded that in patients with a nonthyroidal illness, decreased levels of serum thyroid hormones indicate not only the severity of the illness but also the supposed presence of a hypothyroid state.
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PMID:[Thyroid functions in nonthyroidal illness: specific changes in serum levels of thyroid hormones related in illness and the correlation between thyrotropin and free thyroid hormones in patients with nonthyroidal illnesses]. 647 79

Survival under hypoxia (5% O2; 95% N2) was tested in mice 1 day to 50-weeks-old. Survival Rate (ratio of number of animals that survived 30 min under 5% O2 to total number of animals exposed) and the time from onset of exposure until the last gasp (Survival Time) were maximum in newborn animals and decreased as a function of age. Survival Rate and Survival Time were strongly influenced by drugs affecting cholinergic transmission. Atropine decreased the high survival under hypoxia of 1-week-old mice in a dose-related manner. Physostigmine increased survival under hypoxia in mice 3 to 50-weeks-old. This effect was not related to a peripheral action of the drug since it was not mimicked by neostigmine, a cholinesterase inhibitor without central actions. Moreover, peripheral cholinergic blockade with glycopyrrolate, a quaternary cholinergic blocker, did not prevent the protective effect of physostigmine. Since atropine impairs the ability of very young mice to survive hypoxia and physostigmine improves survival at later ages, it is concluded that a central cholinergic mechanism, possibly related to blood flow regulation, plays a significant role in the acute adaptation to hypoxia.
Stroke
PMID:Survival under hypoxia. Age dependence and effect of cholinergic drugs. 742 86

The diagnosis of Alzheimer's disease (AD) currently relies on history obtained from family or friends and on mental status assessment matched to National Institute of Neurological and Communicative Disorders and Stroke criteria. Progression over time may or may not be typical, suggesting alternate diagnoses such as Lewy body or frontotemporal dementias. Apolipoprotein E genotype does not appear to be useful as a diagnostic marker. The usefulness of brain imaging in AD must be reexamined. Critical events in the natural history of AD, such as institutionalization and loss of ability for self-care, could be used as end points. Loss of ability for instrumental tasks, such as driving, traveling alone, or managing finances, would be preferable for early-stage stabilization studies. Different symptomatic domains of AD (mood, cognition, functional autonomy, behavior, motoricity) can be quantified using specific outcome measures. Although cognitive loss has been considered a core symptom of AD from a regulatory perspective, loss of functional autonomy and behavioral disinhibition are considered more important by clinicians and families. Recently, the availability of new scales has led to an interest in all of these domains. Results from symptomatic drug studies suggest a differential effect of cholinesterase inhibitors on cognition versus muscarinic agonists on functional autonomy and behavior. Hence there is a need to measure these domains separately and, eventually, to attempt combination therapy. Quality of life is a difficult but important dimension of AD therapeutic research, and it requires further methodological research.
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PMID:Update on diagnostic methods, natural history and outcome variables in Alzheimer's disease. 985 96


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