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The presence of monoamines and their cofactors (the pterins and vitamin B6 (pyridoxal phosphate (PLP))) in human cerebrospinal fluid (CSF) can be used as indicators of the biosynthesis and turnover of dopamine and serotonin in the brain. In addition, abnormalities in the CSF levels of these molecules are associated with various neurological diseases, including genetic diseases leading to dopamine and serotonin deficiency. Here, we provide a set of quantitative high-performance liquid-chromatography (HPLC) approaches to determine CSF levels of monoamines and their cofactors. This protocol describes step-by-step procedures for CSF sample preparation for the analysis of different molecules, HPLC calibration and analysis, and data quantification and interpretation. Unlike plasma/tissue/blood samples, CSF requires minimal sample preparation: in this protocol, only the analysis of PLP requires mixing with trichloroacetic acid to release the protein-bound vitamin, centrifugation, and mixing of the supernatant with phosphate buffer and sodium cyanide for derivatization in alkaline conditions. Monoamines are analyzed by HPLC with coulometric electrochemical detection (ED), pterins are analyzed by HPLC with coupled coulometric electrochemical and fluorescence detection, and PLP is analyzed by HPLC with fluorescence detection. The quantification of all compounds is achieved by external calibration procedures, and internal quality control and standards are analyzed in each run. We anticipate that investigation of dopamine and serotonin disturbances will be facilitated by measurements of these compounds in human CSF and other biological samples. The estimated time for the different procedures primarily depends on the electrochemical detector stabilization. Overnight stabilization of this detector is advised, and, after that step, preanalytical equilibration rarely exceeds 3 h.

Background Cerebrospinal fluid (CSF) metabolomic investigations are a powerful tool for studying neurometabolic diseases. We aimed to assess the effect of CSF contamination with blood on the concentrations of selected biomarkers. Methods CSF samples were spiked in duplicate with increasing volumes of whole blood under two conditions: (A) pooled CSF spiked with fresh whole blood and frozen to cause red blood cell (RBC) lysis; (B) pooled CSF spiked with fresh blood and centrifuged (the supernatant with no RBCs was frozen until the moment of analysis). CSF concentrations of amino acids, biogenic amines, pterins, and vitamins were analysed by HPLC coupled with tandem mass spectrometry, electrochemical and fluorescence detection. Results Aspartate, glutamate, taurine, ornithine, glycine, citrulline, pyridoxal 5´-phosphate, 5-methyltetrahydrofolate, and thiamine showed higher values when RBCs were lysed when compared with those of CSF with no RBC, while arginine, 5-hydroxyindoleacetic and homovanillic acids showed lower values. When RBCs were removed from CSF, only some amino acids, thiamine and pyridoxal 5´-phosphate showed moderately higher values when compared with the non-spiked CSF sample. Conclusions CSF-targeted metabolomic analysis is feasible even when substantial RBC contamination of CSF has occurred since CSF centrifugation to remove RBC prior to freezing eliminated most of the interferences observed.

Background Despite dietary intervention, individuals with early treated phenylketonuria (ETPKU) could present neurocognitive deficits and white matter (WM) abnormalities. The aim of the present study was to evaluate the microstructural integrity of WM pathways across the whole brain in a cohort of paediatric ETPKU patients compared with healthy controls (HCs), by collecting DTI-MRI (diffusion tensor magnetic resonance imaging) data and diffusion values (mean diffusivity (MD), radial diffusivity (RD) and fractional anisotropy (FA)). Methods DTI-MRI data and diffusion values (MD, RD, FA) from WM tracts across the whole brain were analized using Tract Based Spatial Statistics (TBSS), in 15 paediatrics TPKU patients (median age: 12 years) and compared with 11 HCs. Areas showing abnormal values in the patient group were correlated (Pearson) with age, lifetime Phe values, last year median and mean Phe, concurrent Phe values in plasma, urine neurotransmitters status biomarkers, and with a processing speed task. Results ETPKU showed bilaterally decreased MD values compared with HCs in the body and splenium of the corpus callosum, superior longitudinal fasciculus, corona radiata and in the posterior limb of the internal capsule. RD values followed a similar pattern, although decreased RD values in PKU patients were also found in the anterior limb of the internal capsule and in the cerebral peduncle. Decreased MD and RD values within the aforementioned regions had significant negative correlations with age, last year median and mean Phe and concurrent Phe values. No correlations were found with monoamines in urine or processing speed task. Conclusions ETPKU patients showed MD and RD values significantly decreased across the whole brain when compared with HCs, and this damage was associated with high Phe values and the age of patients. Despite this microstructural damage, no affectation in processing speed was observed in patients with good metabolic control. DTI-MRI sequences could be used as a technique to quantify WM damage that is difficult to be detect in T1 or T2-weighted images, but also to quantify damage of WM through the follow up of patients with poor metabolic control in prospective studies.

Amino acid analysis in biological fluids is essential for the study of inborn errors of metabolism (IEM) and other diseases. Our aim was to develop a UPLC-MS/MS procedure for the analysis of 25 amino acids and identification of 17 related compounds. Sample treatment conditions were optimized for plasma, urine, cerebrospinal fluid (CSF) and dried blood spots. Amino acids and related compounds were analyzed on a Waters ACQUITY UPLC H-class instrument with a reversed-phase C-18 column using water and acetonitrile with 0.1% formic acid as the mobile phases (run time = 9 min). The detection was performed with a Waters Xevo TQD triple-quadrupole mass spectrometer using positive electrospray ionization in the multiple reaction monitoring mode. The method linearity, intra-assay and inter-assay precision, detection limit, quantification limit and trueness analysis displayed adequate results in both physiological and pathological conditions. Method comparison was performed between UPLC-MS/MS and ion exchange chromatography (IEC) with ninhydrin derivatization, and the methods showed good agreement, except for 4-hydroxyproline, aspartate and citrulline. Paediatrics age-related reference values in plasma, urine and CSF were established and patients with different IEM were easily identified. We report a modified UPLC-MS/MS procedure for the analysis of 42 amino acids and related compounds in different specimens. The method is fast, sensitive and robust, and it has been validated to be an alternative to the traditional IEC procedure as the routine method used in metabolic laboratories. The method greatly decreases the run time of the analysis while displaying good metrological results.

The brain is an early target for organ damage due to high blood pressure. Hypertension is the major modifiable risk factor for stroke and small vessel disease. It has been suggested that cerebral microvascular disease contributes to vascular cognitive impairment. The mechanisms underlying hypertension-related cognitive changes are complex and not yet fully understood. Both high and, especially in the elderly, low blood pressure (BP) have been linked to cognitive decline and dementia. There is some evidence that antihypertensive drug treatment could play a role in the prevention of cognitive impairment through BP control. The BP levels that should be targeted to achieve optimal perfusion while preventing cognitive decline are still under debate.

Stroke is one of the most devastating manifestations of two common diseases, atherosclerosis and hypertension. It represents the second leading cause of death and a major cause of disability worldwide. Besides age (a nonmodifiable risk factor), hypertension is the most important cardiovascular risk factor for developing both ischemic and hemorrhagic stroke, as well as small vessel disease predisposing to lacunar infarction, white matter lesions, and cerebral microbleeds. In addition, hypertension predisposes to atherosclerosis and cardiac diseases (notably atrial fibrillation), thereby promoting cerebral embolism. Inflammatory mechanisms play a central role in the pathogenesis and progression of atherosclerosis, plaque rupture, thrombosis, and stroke. Endothelial dysfunction, in part resulting from excessive production of reactive oxygen species, is an important mechanism of cerebrovascular damage. This article reviews recent data on vascular mechanisms that participate in the pathogenesis of stroke.

The high solar energy density achieved in our simple and cheap Fresnel installation has been used for several surface modifications of metallic materials. This equipment is a very useful tool to apply concentrated solar energy in the field of high and very high temperatures (1500–2000 K). These temperatures are achieved in a few seconds and usually the materials treatments are completed in minutes. Fresnel lens installation is a serious alternative to the conventional equipment for material treatment and even to the large solar installations. In this work we review the surface modifications produced by concentration of solar energy with a Fresnel lens.

Objective: HIV-infection and antiretroviral therapies are associated with energy dysfunction and lipid metabolism in adults. Our aim was to detect a possible carnitine deficiency in HIV-infected children on antiretroviral treatments. We analysed the relation among serum carnitine, its amino-acid precursors (methionine and lysine), clinical evaluation and antiretroviral therapy. Design and setting: Cross-sectional study performed in a tertiary care hospital. Subjects: A total of 79 HIV-infected children on antiretroviral therapy, monitored prospectively in our hospital. Interventions: Antiretroviral therapy included nucleoside analogues plus protease inhibitors and/or non-nucleoside analogues. Carnitine was analysed by an enzymatic-spectrometric procedure, and amino acids by ion exchange chromatography. Reference values of carnitine and amino acids were established in apparently healthy children who underwent presurgical analysis for minor surgery. Results: Serum free and total carnitine, acylcarnitines, methionine and lysine were significantly lower in HIV-infected children compared with our reference values for similar ages (P

Objective: Treatment of phenylketonuria (PKU) patients consists of a phenylalanine-restricted diet supplemented with a tyrosine-, vitamin- and oligoelement-enriched amino-acid mixture. Vitamins and oligoelements may be deficient when compliance with the supplemented special formula is poor. Plasma thiol concentrations (especially homocysteine) depend mainly on B-vitamin intake. Our aim was to evaluate the plasma thiol concentrations (homocysteine, cysteine and glutathione) and their determinants (methionine, cobalamin and folate) in PKU patients under dietary treatment compared with age-matched controls. Design and setting: Cross-sectional study performed in a tertiary care Hospital. Subjects: PKU (42) patients under dietary treatment compared with 42 age-matched controls. Interventions: Plasma total homocysteine, cysteine and glutathione were analyzed by HPLC with fluorescence detection. Plasma phenylalanine and methionine were analyzed by ion exchange chromatography. Serum folate and cobalamin were analyzed by radioimmunoassay procedures. Results: Total homocysteine concentrations were significantly lower in the PKU patients compared with the control group (Students t-test; P

The pathogenesis and clinical significance of cerebral white matter lesions (WML) remain controversial. Most studies have shown that age, hypertension, diabetes mellitus, and a history of stroke or heart disease are the most important factors related to the presence of cerebral WML. Moreover, some studies suggest that the presence of WML are closely related to cerebrovascular disease and cognitive impairment in elderly patients with vascular risk factors, particularly hypertension. In this review, different points of view about cerebral WML are discussed, with special focus on the presence of WML in essential hypertension. Some authors suggest that the presence of WML in hypertensive patients could be considered an early marker of brain damage.

The possible association between the insertion/deletion (I/D) polymorphism of the angiotensin I converting enzyme (ACE) gene and left ventricular hypertrophy (LVH) was investigated in a group of essential hypertensive patients. Seventy-one essential hypertensive patients (35 men and 36 women), aged 51 +/- 1 years, were genotyped by PCR for the I/D polymorphism of the ACE gene. Cardiac morphology and function were assessed by means of M-mode echocardiography. The relative frequencies of the three genotypes, DD, DI, and II, were respectively: 24%, 55%, and 21%. Mean values of left ventricular mass index were 145, 144, and 150 g/m2 for DD, DI, and II genotypes, without significant differences among them (P = 0.82). Likewise, the prevalence of LVH (76%, 64%, and 87%) was not significantly different among the three genotypes (P = 0.23). We conclude that the ACE gene I/D polymorphism is not associated with LVH in essential hypertension. Journal of Human Hypertension (2000) 14, 47-49.