The role of neuroendocrine pathways in prognosis after stroke

A number of neuroendocrine changes have been described after stroke, which may serve adaptive or deleterious functions. The neuroendocrine changes include activation of the hypothalamo-pituitary-adrenal axis, sympathetic nervous system and alterations of several hormonal levels. Alterations of the HPA axis, increased catecholamines, natriuretic peptides and, decreased melatonin and IGF-1 levels are associated with poor post-stroke outcome, although there is no definitive proof of causality. Therefore, it remains to be established whether alteration of neuroendocrine responses could be used as a potential therapeutic target to improve stroke outcome. This article gives an overview of the major neuroendocrine pathways altered by stroke and highlights their potential for clinical use and further neurotherapeutic development by summarizing the evidence for their association with stroke outcome including functional outcome, post-stroke infection, delirium, depression and stroke-related myocardial injury.

A Novel Method for the Assessment of Cortisol Hormone in Different Body Fluids Using A New Photo Probe Thiazole Derivative

A low cost and accurate method for the detection and analytical determination of the cortisol in pharmaceutical preparation, blood serum and urine was developed. The method was based upon the enhancement of fluorescence intensity of the band at 424 nm of the photo probe by different cortisol concentrations in acetonitrile at (pH 5.7, λex = 320 nm). The influence of the different parameters, e.g. pH, solvent, cortisol concentration and foreign ions concentrations that control the enhancement process of fluorescence intensity of the band of photo probe was critically investigated. The remarkable enhancement of the fluorescence intensity at 424 nm in acetonitrile by various concentrations of cortisol was successfully used as a photo- probe for the assessment of cortisol concentration. The calibration plot was achieved over the concentration range 8.0 × 10(-6)-5.5 × 10(-9) mol L(-1) cortisol with a correlation coefficient of 0.998 and a detection limit of 4.7 × 10(-9) mol L(-1). The developed method is simple and proceeds without practical artifacts compared to the other determination methods.

How porphyrinogenic drugs modeling acute porphyria impair the hormonal status that regulates glucose metabolism. Their relevance in the onset of this disease

This work deals with the study of how porphyrinogenic drugs modeling acute porphyrias interfere with the status of carbohydrate-regulating hormones in relation to key glucose enzymes and to porphyria, considering that glucose modulates the development of the disease. Female Wistar rats were treated with 2-allyl-2-isopropylacetamide (AIA) and 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) using different doses of AIA (100, 250 and 500mg/kg body weight) and a single dose of DDC (50mg DDC/kg body weight). Rats were sacrificed 16h after AIA/DDC administration. In the group treated with the highest dose of AIA (group H), hepatic 5-aminolevulinic acid synthase (ALA-S) increased more than 300%, phosphoenolpyruvate carboxykinase (PEPCK) and glycogen phosphorylase (GP) activities were 43% and 46% lower than the controls, respectively, plasmatic insulin levels exceeded normal values by 617%, and plasmatic glucocorticoids (GC) decreased 20%. GC results are related to a decrease in corticosterone (CORT) adrenal production (33%) and a significant reduction in its metabolization by UDP-glucuronosyltransferase (UGT) (62%). Adrenocorticotropic hormone (ACTH) stimulated adrenal production 3-fold and drugs did not alter this process. Thus, porphyria-inducing drugs AIA and DDC dramatically altered the status of hormones that regulate carbohydrate metabolism increasing insulin levels and reducing GC production, metabolization and plasmatic levels. In this acute porphyria model, gluconeogenic and glycogenolytic blockages caused by PEPCK and GP depressed activities, respectively, would be mainly a consequence of the negative regulatory action of insulin on these enzymes. GC could also contribute to PEPCK blockage both because they were depressed by the treatment and because they are positive effectors on PEPCK. These disturbances in carbohydrates and their regulation, through ALA-S de-repression, would enhance the porphyria state promoted by the drugs on heme synthesis and destruction. This might be the mechanism underlying the "glucose effect" observed in hepatic porphyrias. The statistical correlation study performed showed association between all the variables studied and reinforce these conclusions.

Measuring tobacco smoke exposure: quantifying nicotine/cotinine concentration in biological samples by colorimetry, chromatography and immunoassay methods

Procedures to assess tobacco smoke exposure are reviewed and biomarkers used for determining the smoking status of an individual are compared. Methods used to extract these biomarkers from saliva, urine, and blood and the advantages and disadvantages of the assays are discussed. Finally, the procedures used to measure the levels of cortisol, a stress hormone speculated to be linked to nicotine metabolism, are discussed.

Clinical measurement of steroid metabolism

Analysis of steroids in biological samples is used routinely in the diagnosis of endocrine disorders. Binding assays (radioimmunoassays, immunosorbant immunoassays and non-radioactive immunoassays) are reported often for the analysis of single steroids in plasma and urine. Chromatographic methods (high-performance liquid chromatography and gas chromatography) are used for steroid profiling where complex mixtures of steroids are analysed and the activity of biosynthetic and metabolic pathways deduced. Mass spectrometry is the ideal reference technique for detection of steroids, allowing high specificity and sensitivity. This review describes the practical issues concerning the quality of the assays performed and the potential pitfalls facing the analyst in the design of such methods. Novel approaches for the quantification of steroids, including microarrays and stable-isotope tracers are described, with these being applied in the research environment as opposed to routine biochemical laboratories.

Quality control in the determination of cortisol in plasma/serum by using, on every sample, two different three-step separation methods including ultrafiltration, restricted-access high-performance liquid chromatography and reversed-phase high-performance liquid chromatography, and contrasting results to immunoassays

Tests of HPLC columns with restricted access, polymer covered alumina, polymer, and different ODS phases showed that base-acid compatible ODS columns gave the best peak shapes of cortisol, internal standard, as well as of plasma/serum (P/S) matrix components. Further trials with cortisol in P/S showed that three separation steps were essential in order to obtain chromatographic data which were superior to immunoassay data. Also, sufficient confidence in results required determination of each sample with two newly developed separation methods: (a) pre-separation with a restricted access column, concentration of the desired cut with a 20 mm base-acid compatible ODS column, and analysis with a 250 mm column filled with the same ODS; (b) pre-separation with an ultrafilter followed by the last two steps in (a). For detection UV was preferred over fluorescence. This twin multistep chromatography showed that immunoassays were very treacherous in that they produced a spectrum of results ranging from good to untenable without any warning whatever about functionality. The measurement of official controls, with reference values derived via gas chromatography-isotope dilution mass spectrometry, also demonstrated the superiority of the double HPLC method.

High-performance liquid chromatographic analysis of corticosteroids

This review presents recent developments in high-performance liquid chromatographic (HPLC) analysis of corticosteroids for the determination of clinically important steroids in biological specimens. Various sample preparation techniques are described.

Column-switching high-performance liquid chromatographic system with a laser-induced fluorimetric detector for direct, automated assay of salivary cortisol

In order to measure human stress, an easy and rapid, fully automated method for the determination of cortisol in saliva has been developed, using column-switching high-performance liquid chromatography with laser-induced fluorescence detection, which involves post-column labeling with sulfuric acid. The developed system requires only 0.1 ml of saliva, and a simple pretreatment consisting of dilution and filtration is sufficient. The column-switching system consisted of a Polymer-Coated Mixed-Functional silica (PCMF) column for deproteinization, and a CN column for frontal concentration and separation. An ODS column in place of the CN provided a better separation, but required a post-column make-up of water for safe reaction. Detection limit of cortisol was 8 fmol (signal-to-noise ratio = 3), which is adequate for routine determination of normal levels of cortisol (1-20 pmol/ml). The analysis time was about 40 min and reproducibility was excellent with an R.S.D. of less than 5%.

Assay of human plasma cortisone by liquid chromatography: normal plasma concentrations (between 8 and 10 a.m.) of cortisone and corticosterone

A high-performance liquid chromatographic method using ultraviolet detection to quantitate human plasma concentrations of cortisone simultaneously with cortisol and corticosterone is described. The method is based on the use of an octadecyl silica column (100 mm x 2 mm I.D., 3 microns), an ultraviolet absorbance detector (242 nm) with a 10 mm path length flow-cell, and a mobile phase composed of water-tetrahydrofuran-acetonitrile (82:10:8, v/v) containing 5 ml/l triethylamine and citric acid to adjust the pH of the buffer to 6.5. Flumethasone is used as the internal standard. The detection limit of the method for the three steroids is 300 ng/l using a 1-ml sample. The average inter-assay coefficient of variation for cortisone is 3.3% and the average recovery is 100.8%. Possible interferences from common drugs and endogenous and exogenous steroids in the method have been studied. Plasma concentrations (drawn from 8 to 10 a.m.) of cortisone and corticosterone for 43 normal volunteers have been determined.

Fluorimetric detection of serum corticosterone using high-performance liquid chromatography

A simple, sensitive, specific and reproducible method for the determination of corticosterone concentrations in rat serum using high-performance liquid chromatography (HPLC) with fluorimetric detection is described. Corticosterone is detectable down to 0.1 ng injected onto the HPLC column. Cortisol is used as an internal standard. Ethyl acetate was used for both initial serum corticosteroid extraction and the subsequent fluorophore extraction after sulfuric acid hydrolysis; thus sulfuric acid does not enter the HPLC system. The resultant fluorophores for both corticosterone and cortisol are stable for at least two weeks at ambient temperature not requiring storage at -20 degrees C. The procedure is highly suitable for use with HPLC systems utilising automatic sample injectors. The method is specific for corticosterone; dexamethasone, cortisone and gonadal steroids are not detectable and do not interfere in this assay.

Determination of urinary free cortisol by high performance liquid chromatography with sulphuric acid-ethanol derivatization and column switching

A rapid and highly sensitive determination method for urinary free cortisol has been developed using reversed phase high performance liquid chromatography (HPLC) with a precolumn for sulphuric acid-ethanol fluorescence derivatization and column switching. Urinary cortisol, eluted from the octadecylsilane-bonded silica (ODS) minicolumn with 90% aqueous ethanol, was derivatized with the addition of sulphuric acid only at ambient temperature. Cortisol derivatives injected directly onto the ODS precolumn were purified on-line. After switching the columns, the cortisol derivative was separated on an ODS analytical column with a retention time of 15.3 min and monitored at an emission wavelength of 520 nm (exitation wavelength of 365 nm) to decrease the detection limit to 0.26 microgram/dL (signal-to-noise ratio = 3). The automated HPLC operation resulted in good reproducibility and recovery of the stable cortisol derivative at 5 degrees C.

Determination of serum cortisol by reversed-phase liquid chromatography using precolumn sulphuric acid-ethanol fluorescence derivatization and column switching

An assay method for serum cortisol, using precolumn sulphuric acid-ethanol fluorescence derivatization and reversed-phase liquid chromatography with a column-switching technique, has been developed. The crude precolumn fluorescence cortisol derivative was prepared by the addition of sulphuric acid to serum deproteinized with ethanol, and directly injected onto an octadecylsilane-bonded silica gel (ODS) precolumn for concentration and purification. After switching columns the samples were separated using an ODS analytical column and monitored fluorimetrically. When the pH of the mobile phase in the analytical separator decreased to 1.85, the emission wavelength of the cortisol derivative changed to 520 nm (excitation of 365 nm) and the fluorescence intensity increased. Among the sulphuric acid-ethanol derivatives of various steroids, cortisol, corticosterone and testosterone emitted fluorescence. However, their retention times differed from those of the cortisol derivatives (12.5 min). The detection limit of cortisol was 0.3 micrograms/dl (signal-to-noise ratio of 3). Use of the fully automated column-switching system contributed to good reproducibility and recovery.

Post-column reactors for sensitive and selective detection in high-performance liquid chromatography: categorization and applications

The increasing interest in the rapid trace analysis of large series of biomedical samples using column liquid chromatographic techniques requires the use of well balanced combinations of sample pretreatment, separation and detection techniques. In such work, selectivity, sensitivity and reproducibility are the key parameters. The application of automated or semi-automated on-line pre-column technology and/or post-column reaction detection are excellent ways to meet these requirements. A critical review is presented of the theoretical background of on-line post-column reactors with emphasis on their categorization, viz., open-tubular, packed-bed, segmented-stream and hollow-fibre membrane reactors. The evaluation of these reactor systems is performed by discussing selected applications of, for instance, systems based on electrochemical and redox, hydrolytic, photochemical, ion-pairing, true chemical derivatization, peroxyoxalate chemiluminescence and solid-phase reactions. As automation is becoming even more important, a number of labelling procedures, which can be performed in an on-line pre-column mode, are briefly discussed and a comparison is made between the potential of on-line pre- and post-column procedures.

Clinical analysis of individual steroids by column liquid chromatography

At present, there are various LC methods available for the determination of estriol, aldosterone, and cortisol in urine, and for cortisol, cortisone, 11-deoxycortisol, corticosterone, 17-hydroxyprogesterone, estriol, vitamin D isomers, and various exogenous glucocorticoids in serum. The LC methods are more specific than the currently available RIAs or homogenous immunoassays. However, whether the data obtained by more specific LC methods are better clinically than the commonly used immunoassays for these steroids must still be proven. In this review, I have critically evaluated various LC methods currently available for the routine determination of clinically important steroids in the clinical laboratories. A complete evaluation and advantages and disadvantages of alternative techniques are beyond the scope of this review. However, the readers are urged to refer to the review articles and chapters listed in the reference section.

High-performance liquid chromatography of steroid hormones

Although a considerable amount of work has been carried out in the last ten years in developing methods for the separation of steroids by HPLC, it is still not widespread for the reasons discussed above. There is however no doubt that further developments in HPLC technology, in increasing sensitivity and/or specificity of detection systems, perhaps with microbore columns, may lead to an increase in the use of this powerful analytical procedure as an additional separation method to improve specificity of assay. Solution of the problem of simple interfacing of HPLC systems with mass spectrometers (discussed in another chapter by Games) should further increase the application of HPLC. HPLC is of particular value in providing a means of separating unstable compounds prior to assay by relatively nonspecific quantitation methods. Most steroids do not fall into this category, but the steroid vitamin D and its metabolites do and HPLC has proved in this area to be invaluable (see chapter by Jones & DeLuca). There are a multiplicity of different HPLC systems for the separation of steroids, varying in column type (and manufacturer), solvent composition and method of elution, temperature of elution, etc., and only a few attempts have been made to rationalise these data. It would therefore seem that a fruitful area of future study would be the investigation of computerised systems for the selection and optimisation of HPLC systems for particular steroid separations.

Plasma L-tryptophan/neutral amino acid ratio and dexamethasone suppression in depression

We examined the ratio of plasma L-tryptophan (L-TRP) to other neutral amino acids (NAA) in normal controls and depressed patients undergoing a dexamethsone suppression test (DST). The L-TRP/NAA ratio discriminated controls from patients; however, there was no difference in the mean L-TRP/NAA ratio between DST suppressors and nonsuppressors. The cortisol level measured at 1600h postdexamethasone and the L-TRP/NAA ratio were positively correlated. The 1600h postdexamethasone cortisol levels accounted for 24% of the variance of Hamilton Depression Rating Scale ( HDRS ) scores. The inclusion of L-TRP/NAA ratios with 1600h postdexamethasone cortisol levels in a multiple regression equation resulted in an increase in this value and accounted for 65% of the variance in HDRS scores. The finding supports the use of multivariate biological models in depression.

Liquid chromatographic assay of urinary free cortisol

Cortisol in concentrated sulfuric acid forms two major fluorescing compounds which are separated by chromatography on a reversed-phase column. Based on this reaction, urine free cortisol, after double extraction was assayed by high-performance liquid chromatography with fluorescent detection. The method is sensitive, rapid, and free from interferences. The values by this method are 30% lower than radioimmunoassay. In addition to Cushing's syndrome, patients with acute pancreatitis had elevated levels of urinary free cortisol which parallel urinary amylase levels while patients with myocardial infarction had normal levels. Urinary free cortisol showed diurnal variation with elevated values early in the morning.