Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0085580 (essential hypertension)
 14,686 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Our previous studies have shown that a suppressed pressure natriuresis may contribute to the hypertensive mechanism in patients with essential hypertension (EHT), particularly in low renin patients (LRH). In this study, in order to clarify the role of renal dopaminergic activity in the blunted natriuresis of LRH, the conversion of 1-dopa (DOPA) to dopamine (DA) in the kidneys was investigated in 9 normotensive subjects (NT) and 20 EHT, including 15 normal renin EHT (NRH) and 5 LRH. All subjects were hospitalized and received a constant diet (Na:120mEq, K:75mEq daily). Plasma DOPA concentration (p-DOPA:HPLC-ECD), creatinine clearance (Ccr), urinary excretion of sodium (UNaV) and DA (UDA), as well as fractional excretion of sodium (FENa) were measured before and after the single oral administration of 1-DOPA (400mg). DOPA administration caused a significant increase of p-DOPA, UDA and FENa with undetectable DOPA levels in the urine in EHT. In addition, under the basal condition, UDA correlated positively with p-DOPA or the product of p-DOPA x Ccr, which might reflect the DOPA delivery at the renal proximal tubule. No significant difference was found in p-DOPA and the product of p-DOPA x Ccr among NT, NRH and LRH. However, the ratio of UDA/(p-DOPA x Ccr), which may indicate the conversion from DOPA to DA in the kidneys, was lower in EHT, especially in LRH, than that in NT. These results suggest that a reduced renal conversion from DOPA to DA may contribute to the attenuated natriuresis as well as renal dopaminergic activity in LRH.
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PMID:Attenuated renal production of dopamine in patients with low renin essential hypertension. 266 52

We report a reliable method for determining DOPA levels in plasma and cerebrospinal fluid. The method is based on complete conversion of DOPA to dopamine and quantification by HPLC-ECD of the dopamine formed. Lower limit of detection was 0.5 nmol/l. No differences in plasma DOPA levels were found between normal children (0-15 yr, n = 60), normal adults (n = 39) and patients with essential hypertension (n = 40) or Parkinson's disease (no DOPA therapy, n = 30). In normal individuals and in patients with essential hypertension venous plasma levels were higher than arterial levels (10.2 vs 9.3 nmol/l, p less than 0.001, V/A ratio 1.11 (SD 0.08), n = 15). Sympathetic stimuli (standing, tilting, bicycle exercise, tyramine) did not influence DOPA levels. In untreated depressed patients (n = 10) and in non-parkinsonian neurological patients (n = 12) cerebrospinal fluid levels of DOPA were 4.5 (SD 2.4) and 5.2 (SD 1.3) nmol/l respectively. A direct method for the measurement of DOPA by HPLC-ECD after deproteinization of plasma is also described and compared with the conversion method. Good agreement was found when plasma DOPA levels exceeded 0.25 mumol/l (y(conversion method) = 0.943x (direct method) + 0.118; n = 60; r = 0.985). The direct method, because of greater simplicity and the possibility of simultaneous measurement of the DOPA metabolite 3-O-methyldopa, is the method of choice with plasma samples from DOPA-treated patients. In non-DOPA treated individuals the conversion method is superior and has proved to be an accurate and sensitive method for the determination of DOPA levels in plasma and cerebrospinal fluid.
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PMID:Determination of 3,4-dihydroxyphenylalanine (DOPA) in plasma and cerebrospinal fluid by high performance liquid chromatography with electrochemical detection. 314 24

To determine the role of the parasympathetic system in the development of essential hypertension, the concentrations of acetylcholine (ACh) as a parasympathetic marker and norepinephrine (NE) as a sympathetic marker were measured simultaneously in the heart of spontaneously hypertensive rats (SHR) at 4, 10 and 27 weeks of age, and in age-matched control Wistar-Kyoto rats (WKY). ACh was measured using a highly sensitive and specific high performance liquid chromatography-electrochemical detection (HPLC-ECD) attached to a newly developed immobilized fixed enzyme column system. NE was measured by conventional HPLC-ECD. The ACh concentration decreased in the order right atrium (RA) greater than left atrium (LA) greater than right ventricle (RV) greater than interventricular septum (IVS) greater than left ventricle (LV) in both SHR and WKY of all age groups, and NE showed an almost identical pattern. The concentration of ACh tended to increase and that of NE to decrease with age in both strains. The concentrations of ACh in the heart were significantly different in the two strains, with the levels being consistently higher in the SHR strain regardless of age, although differences were most significant at 10 weeks. The mean concentrations of NE were higher in SHR than in WKY, but the differences between the two strains were significant only in the RV and IVS. The functional meanings of a given tissue concentration of a neurotransmitter are still controversial. However, the increase in SHR heart ACh concentration, in parallel with the development of hypertension, may reflect the augmented parasympathetic activity counteracting or compensating for the augmented sympathetic drive in the early stage of hypertension.
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PMID:Acetylcholine and norepinephrine concentrations in the heart of spontaneously hypertensive rats: a parasympathetic role in hypertension. 361 80

Measurement of free plasma metanephrines (metanephrine and normetanephrine), usually performed by high-performance liquid chromatography with electrochemical detection (HPLC-ECD), has been recommended as the single biochemical test of choice for the diagnosis of pheochromocytoma. Alternatively, a widely available, simple means to measure these biomarkers with enzyme immunoassay (EIA) needs to be studied. The aim of this study was to investigate the diagnostic efficacy of such a method in comparison with (131)I-metaiodobenzylguanidine (MIBG) whole body scan (WBS) in patients with pheochromocytoma. We enrolled patients undergoing (131)I-MIBG WBS due to clinical findings suggestive of pheochromocytoma (n = 45), and patients with primary hypertension (n = 36). All subjects had blood tests for free plasma metanephrine (MN) and normetanephrine (NM) with a commercially available EIA kit. WBS was positive in 30 pheochromocytoma patients and negative in 15 refuted ones, with 100% accuracy. The sensitivity, specificity and accuracy of MN and NM in combination (either or both positive) were 96.7%, 86.3% and 90.1%, showing comparable diagnostic performance both to (131)I-MIBG WBS (all p > 0.1), and also to the same markers measured with HPLC-ECD reported in the literature. These results showed that the EIA method may be eligible as an alternative to HPLC-ECD for plasma metanephrine determination in the identification of pheochromocytoma.
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PMID:Comparison of free plasma metanephrines enzyme immunoassay with (131)I-MIBG scan in diagnosis of pheochromocytoma. 1861 18

A wide range of waste characterization methods are available, each developed for a specific purpose such as determining compost stability, or for landfill acceptance criteria. Here test methods have been evaluated for the purpose of assessing waste treatment process performance and monitoring the diversion of biodegradable municipal waste (BMW) from landfill. The suitability factors include the timescale of the method, applicability to a wide range of materials and ability to indicate the long-term biodegradability of organic waste samples. The anaerobic test methods, whilst producing reliable results, take at least several weeks to complete, therefore, not allowing for regular routine analysis often required for diversion assessments. Short-term tests are required which can correlate with, and, therefore, estimate, values obtained from long-term anaerobic methods. Aerobic test methods were found to offer a significantly improved timescale compared with anaerobic test methods; however, they have limitations due to not measuring the full extent of sample biodegradability. No single test method was found to be completely sufficient for routine biodegradability analysis suitable for monitoring the BMW diversion from landfill. Potential areas for further research include spectrographic FT-IR or enzyme-based approaches such as the ECD or EHT methods.
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PMID:Test methods to aid in the evaluation of the diversion of biodegradable municipal waste (BMW) from landfill. 1934 68