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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated the cardiovascular consequences of acute intoxication by the organophosphate poison, mevinphos (Mev), and delineated the underlying mechanism. Based on on-line power spectral analysis of systemic arterial pressure (SAP) signals in rats anesthetized and maintained by propofol, we identified two distinct phases after intravenous administration of Mev (160 or 320 microg/kg). Phase I was characterized by transient hypertension and mild tachycardia, concurrent with an increase in the very high-frequency (BVHF; 5-9 Hz), high-frequency (BHF; 0.8-2.4 Hz), low-frequency (BLF; 0.25-0.8 Hz),and very low-frequency (BVLF; 0-0.25 Hz) components of SAP signals. Phase II exhibited significant hypotension, a reversal of the BVHF and BVLF power to control levels, and further reduction in the power density of both BHF and BLF components to below baseline. Microinjection of Mev (2 microg) into the bilateral nucleus reticularis ventrolateralis (NRVL), the medullary origin of sympathetic neurogenic vasomotor tone, essentially duplicated those phasic cardiovascular changes. Similarly, sympathoexcitatory NRVL neurons exhibited respectively an elevation and a decline in their spontaneous activities during Phase I and Phase II Mev intoxication. We conclude that the progressive accumulation of acetylcholine over time induced by a direct inhibition of Mev on cholinesterase in the NRVL may be responsible for the phasic changes in cardiovascular events over the course of acute Mev intoxication. Whereas the initial amount of acetylcholine is excitatory to NRVL neurons, overstimulation by the amassed acetylcholine results instead of an inhibitory action.
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PMID:Spectral changes in systemic arterial pressure signals during acute mevinphos intoxication in the rat. 1119 55

We have previously reported that the angiotensin system in the anterior hypothalamic area (AHA) is enhanced in spontaneously hypertensive rats (SHR) and that this enhancement is involved in hypertension in SHR. In addition, acetylcholine (ACh) release is increased in the rostral ventrolateral medulla (RVLM) of SHR, which has also been shown to be involved in hypertension in SHR. In this study, we examined whether the enhanced angiotensin system in the AHA of SHR is related to the increase in cholinergic inputs to the RVLM. Electrical stimulation in the AHA produced a pressor response and an increase in firing rate of RVLM barosensitive neurons. These responses were inhibited and enhanced by RVLM application of the muscarinic receptor antagonist scopolamine and the cholinesterase inhibitor physostigmine, respectively. AHA stimulation also produced release of ACh in the RVLM. Microinjections of angiotensin II and carbachol into the AHA produced pressor responses. The pressor response to angiotensin II was inhibited by scopolamine microinjected into the RVLM, although this produced no effect on the response to carbachol. In SHR, although not in Wistar-Kyoto rats, microinjection of losartan into the AHA inhibited pressor responses to physostigmine. However inhibition was not observed in response to the directly acting muscarinic receptor agonist carbachol, injected into the RVLM. These findings demonstrate that angiotensin receptor activation or electrical stimulation in the AHA produce a pressor response via an increase in ACh release in the RVLM. In addition, the present study suggests that the enhanced angiotensin system in the AHA of SHR increases cholinergic inputs to the RVLM, which leads to increases in blood pressure.
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PMID:Activation of hypothalamic angiotensin receptors produces pressor responses via cholinergic inputs to the rostral ventrolateral medulla in normotensive and hypertensive rats. 1238 57

The aim of this study was to verify which risk factors for coronary artery disease (CAD) are independently correlated with butyrylcholinesterase (BChE) activity. We studied 88 White individuals (43 males) aged 47.3+/-15.7 years (mean+/-SD; range: 14.0-80.0 years) including 38 with hyperlipidemia, 30 with hypertension and 5 with diabetes mellitus (DM). Simple correlation analysis showed that BChE activity was positively correlated with age, sex, body mass index, hypertension and DM, as well as with triglycerides (TGs), total cholesterol, low-density lipoprotein cholesterol and apolipoprotein B (Apo B). However, after a step-wise multiple regression analysis, the only risk factors for CAD that showed independent correlations with BChE activity were, in descending order of importance, Apo B, TGs and DM. Our findings seem to reinforce suggested associations of BChE activity with lipoprotein synthesis and with hypertension, as well as supporting previous data on the relation of BChE activity with disturbances found in diabetes mellitus.
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PMID:Butyrylcholinesterase activity and risk factors for coronary artery disease. 1238 87

To elucidate risk factors for cerebral amyloid angiopathy (CAA) in the elderly, we have investigated 201 autopsy cases of elderly Japanese (ages: 62-104 years), including 82 patients with Alzheimer's disease (AD). Severity of CAA showed no relationship with the history of hypertension, hyperlipidemia, or diabetes mellitus, nor with severity of atherosclerosis of cerebral and systemic arteries, indicating that common vascular risk factors would not be related to CAA. Incidence and severity of CAA were significantly higher in the AD cases compared with the non-AD cases (p < 0.0001). Severity of CAA correlated with densities of senile plaques and neurofibrillary tangles in total and non-AD cases, although the correlations were not significant within the AD cases. Associations of genetic polymorphisms with CAA have been investigated for genes of apolipoprotein E (APOE), presenilin 1 (PS1), alpha1-antichymotrypsin (ACT), butyrylcholinesterase, alpha2-macroglobulin, and paraoxonase. Severity of CAA in APOE epsilon4 carriers is significantly higher than that in non-epsilon4 carriers in total cases, although no significant difference was found in the CAA severity between the epsilon4 carriers and non-epsilon4 carriers within the AD or non-AD group. An intronic polymorphism of PS1 was significantly associated with the severity of CAA, indicating that the PS1 2/2 genotype may be related to lower risk of CAA. A polymorphism in the signal peptide sequence of ACT was significantly associated with the CAA severity in the AD group. Our results suggest that CAA shares risk factors with AD and that multiple genetic factors would be associated with the risk of CAA in the elderly.
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PMID:Risk factors for cerebral amyloid angiopathy in the elderly. 1248 Jul 32

Vascular dementia (VaD) is the second-most-common cause of dementia in the elderly, after Alzheimer's disease (AD). VaD is defined as loss of cognitive function resulting from ischemic, hypoperfusive, or hemorrhagic brain lesions due to cerebrovascular disease or cardiovascular pathology. Diagnosis requires the following criteria: cognitive loss, often predominantly subcortical; vascular brain lesions demonstrated by imaging; a temporal link between stroke and dementia; and exclusion of other causes of dementia. Poststroke VaD may be caused by large-vessel disease with multiple strokes (multiinfarct dementia) or by a single stroke (strategic stroke VaD). A common form is subcortical ischemic VaD caused by small-vessel occlusions with multiple lacunas and by hypoperfusive lesions resulting from stenosis of medullary arterioles, as in Binswanger's disease. Unlike with AD, in VaD, executive dysfunction is commonly seen, but memory impairment is mild or may not even be present. The cholinesterase inhibitors used for AD are also useful in VaD. Prevention strategies should focus on reduction of stroke and cardiovascular disease, with attention to control of risk factors such as hypertension, diabetes mellitus, hypercholesterolemia, and hyperhomocysteinemia.
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PMID:Vascular dementia: distinguishing characteristics, treatment, and prevention. 1280 86

The diagnosis and treatment of vascular dementia (VaD) are particularly challenging because of its multiple causal lesions and the variety of its clinical presentations. Even poststroke dementia cases may be due to preexisting Alzheimer's disease. Diagnostic criteria for clinical trials have been implemented quite recently. Of the vasodilator agents, only the ergoloid mesylates have shown mild benefit. The calcium channel blocker nimodipine appears to be useful in subcortical VaD. Of the nootropic agents, memantine appears to be promising. Pentoxifylline produced significant improvement in multi-infarct VaD. Aspirin, triflusal and Ginkgo biloba extract were associated with some stabilization of dementia progression, perhaps due to their antiplatelet effects. Acetyl-cholinesterase inhibitors appear to be useful in improving memory and activities of daily living in VaD. Results of a large trial of donepezil in VaD should be available soon. Hyperbaric oxygen has been reported to be effective in Binswanger's disease. From the public health perspective, stroke prevention, particularly in atrial fibrillation, and the early and adequate treatment of arterial hypertension clearly decrease the incidence of VaD.
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PMID:Perspectives in the treatment of vascular dementia. 1284 69

Development of dementia depends on genetic susceptibility and on risk factors accessible to primary prevention. Among the latter, vascular risk factors are well defined: prevention of hyperhomocysteinemia, diabetes mellitus, hypercholesterolemia, and, to some extent, of arterial hypertension could avoid the cognitive decline of dementia. Estrogen replacement therapy, antiinflammatory drugs, alcohol, vitamin E and intellectual activities seem efficacious in term of primary prevention. When dementia is present, only vitamin E, selegiline and some antiinflammatory drugs have proved efficacy compared to placebo to slow the cognitive decline. Long-term effects of cholinesterase inhibitors need to be investigated in future trials.
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PMID:[Prevention of dementia: is it possible?]. 1286 24

Alzheimer's disease patients with hypertension or other vascular risk factors have been shown to receive greater symptomatic benefits than patients with strictly Alzheimer's disease following short-term treatment with rivastigmine, an inhibitor of acetylcholinesterase and butyrylcholinesterase. We evaluated the long-term efficacy of rivastigmine in Alzheimer's disease patients with or without hypertension. Subjects in a 26-week placebo-controlled trial of rivastigmine entered an open-label extension study for 104 weeks. Efficacy measures included the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog), Progressive Deterioration Scale (PDS) and Global Deterioration Scale (GDS). Subjects were stratified by the presence or absence of hypertension at baseline. At 104 weeks, there was a trend for hypertensive patients from the original rivastigmine 6-12 mg/day group (early starters), who received rivastigmine for the full 104 weeks) to have better ADAS-cog scores than the original placebo group (late starters), who received open-label rivastigmine for the last 78 weeks only). Significant treatment differences were observed in the hypertensive subgroup on the PDS and GDS. In non-hypertensive patients, changes from baseline at week 104 were similar in 'early' and 'late' starters of rivastigmine treatment. The additional apparent benefits on disease progression detected in patients with hypertension and Alzheimer's disease may be linked to drug effects on cerebrovascular factors. These findings may have an important influence on the way cholinesterase inhibitors are prescribed.
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PMID:Potential long-term effects of rivastigmine on disease progression may be linked to drug effects on vascular changes in Alzheimer brains. 1468 63

Cardiac parasympathetic activity reduces susceptibility to potentially lethal ventricular arrhythmias in heart failure and ischemic heart disease. This influence is mediated in large part by antagonism of the adverse cardiac effects of sympathetic overactivity ("indirect" parasympathetic activity) in addition to the "direct" effects of muscarinic stimulation. Nitric oxide modulates parasympathetic cardiac signaling in some animal models, but human data are lacking. We have investigated the influence of endogenous nitric oxide on cardiac responses to parasympathetic stimulation in healthy humans. In 18 volunteers, we studied chronotropic and inotropic responses to muscarinic stimulation, both before and after prestimulation with isoproterenol. Cardiac muscarinic stimulation was achieved using an intravenous bolus of the short-acting cholinesterase inhibitor, edrophonium. Responses were assessed during a background infusion of a nitric oxide synthase inhibitor (N(G)-monomethyl-L-arginine [L-NMMA]), placebo (saline), or phenylephrine (vasoconstrictor control) in a single-blind, random order, crossover protocol. L-NMMA did not affect chronotropic responses to edrophonium alone (direct parasympathetic activity). The decrease in heart rate attributable to "indirect" parasympathetic activity (derived by comparison with the effect of edrophonium during concurrent adrenergic stimulation) was substantially attenuated by L-NMMA in comparison to both control infusions. No modification of muscarinic inotropic responses by L-NMMA was apparent in comparison to the vasoconstrictor control. Nitric oxide exerts a powerful facilitating influence on indirect (antiadrenergic) but not direct human cardiac parasympathetic control. Stimulation of the endogenous nitric oxide pathway might enhance parasympathetic protection against the adverse influences of cardiac sympathetic overactivity.
Hypertension 2004 May
PMID:Nitric oxide and cardiac muscarinic control in humans. 1503 54

Significant progress in the field of VaD resulted from publication of the NINIDS-AIREN Diagnostic Criteria for VaD (G.C. Roman, T.K. Tatemichi, T. Erkinjuntti, et al., Vascular dementia (VaD): diagnostic criteria for research studies. Report of the NINDS-AIREN International Workshop. Neurology 43 (1993) 250-260). Epidemiological studies confirmed the importance of VaD as the second most common cause of dementia in the elderly, representing 15-20% of all cases of dementia. In Europe and North America, Alzheimer's disease (AD) predominates over VaD in a 2:1 ratio; in contrast, in Japan and China VaD accounts for almost 50% of all dementias. Case-control studies have identified risk factors for VaD including ageing, hypertension, diabetes mellitus, hyperlipidemia, recurrent stroke, cardiac disease, smoking, sleep apnea, and more recently, hyperhomocysteinemia, among others. Hypertension treatment may prevent VaD and AD. This finding has enormous importance from the Public Health viewpoint to decrease the future number of patients with dementia in the elderly. Along with advances in the field of VaD came a number of controversies and damaging misconceptions and myths. Myth no. 1--Vascular dementia is a non-entity: The false idea that VaD does not exist is particularly destructive because it creates the perspective that VaD is unworthy of study or research. A condition that either does not exist or represents only a minute proportion of all cases of dementia in the elderly, lacks public health relevance and becomes a low priority for research by funding agencies and industry. In fact, vascular brain lesions are the commonest and most important component of dementia in the elderly. Myth no. 2--Vascular dementia is so difficult to diagnose that only experts can recognize and identify it accurately: VaD does exist and the diagnosis of post-stroke VaD, in particular is straightforward. Most cases fulfill NINDS-AIREN criteria for probable VaD; i.e., (1) there is acute onset of dementia demonstrated by impairment of memory and two other cognitive domains, such as orientation, praxis or executive dysfunction; (2) relevant cerebrovascular lesions are demonstrated by neuroimaging; and (3) a temporal relation between stroke and cognitive loss is evident. In the donepezil trials on VaD, post-stroke dementia represented about 75% of the >1,200 patients enrolled. Myth no. 3--Improvement in clinical trials of cholinergics in VaD is due to underlying AD, not to the vascular lesions. Experimental, clinical and pathological evidence has demonstrated cholinesterase deficits in VaD (independently of any concomitant AD pathology), including low acetylcholine in cerebrospinal fluid, and reduced choline acetyltransferase (ChAT) in the brain.
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PMID:Facts, myths, and controversies in vascular dementia. 1553 19


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