Low Urinary Free Cortisol as a Risk Factor for Patients with Variceal Bleeding.

Specificity and reliability issues of the current cortisol assessment methods lead to limitations on the accurate assessment of relative adrenal insufficiency. Although free cortisol provides a more accurate evaluation of adrenal cortisol production, the expense and time-consuming nature of these assays make them impractical for routine use. Research has, thus, focused on alternative methods, such as indirectly measuring free cortisol using Coolens' equation or directly assessing salivary cortisol concentration, which is considered a more favorable approach despite associated challenges like sampling issues and infection risks.

Urinary free cortisol is a reliable index of adrenal cortisol production in patients with liver cirrhosis.

Background: The measurement of total and free cortisol has been studied as a clinical index of adrenal cortisol production in patients with liver cirrhosis. Correlations between free plasma and salivary cortisol have previously been reported in stable cirrhotic patients. Urinary free cortisol constitutes an index of adrenal cortisol production; however, it has never been used in assessing adrenal function in patients with liver cirrhosis.

Examining barbiturate scaffold for the synthesis of new agents with biological interest.

Barbiturates have a long history of being used as drugs presenting wide varieties of biological activities (antimicrobial, anti-urease and antioxidant). Reactive oxygen species are associated with inflammation implicated in cancer, atherosclerosis and autoimmune diseases. Multitarget agents represent a powerful approach to the therapy of complicated inflammatory diseases.

Modern pediatric formulations of the soft candies in the form of a jelly: determination of metoclopramide content and dissolution.

In pediatrics, it is crucial to ameliorate the unpleasant taste of oral pharmaceutical formulations in order to facilitate patient compliance. Scientists' attempt to develop modern products for children is included among the new trends in pharmaceutical technology. Designing the preparation procedures and selecting the age-appropriate dosage form should be based on a benefit-risk approach, taking into account safety, efficacy, ease of use and accessibility to the patient.

A new descriptor via bio-mimetic chromatography and modeling for the blood brain barrier (Part II).

Within the context of drug design methodology for the central nervous system (CNS), a predictive model which can shorten the process of finding new candidate drugs was developed. Therefore, the retention time of 51 molecules which are clinically established to enter the blood brain barrier (BBB), were recorded on two HPLC columns. For this purpose, a lipophilic butyl (C) stationary phase was used to simulate the behavior of a drug regarding BBB permeability and a zwitterionic-HILIC to simulate blood.

Chemometric of the retention mechanism on butyl column: effect and relation of pH and pKa.

Reversed phase chromatographic separations are optimized for analytes containing ionizable groups by adjustment of pH of mobile phases. As it seems the pK(a). values of compounds affect their retention because of the variety in their solvation.

A Complementary Study of Mechanisms and Behaviors in Chromatography via Modeling.

Evolution in preparation of chromatographic columns has created the need for studying and evaluating them with the use of smart software. This research is an attempt to compare the retention mechanism between two stationary phases (butyl and phenyl) with the use of multivariate analysis for a large number of probes. Partial least squares has the ability to spot either major or minor differences in the chromatographic behavior of probes, with regard to changes in the stationary or mobile phases.

Using the partial least squares method to model the electrospray ionization response produced by small pharmaceutical molecules in positive mode.

Rationale: The signal intensity in electrospray ionization mass spectrometry (ESI-MS) positive mode is affected by parameters that are related to the physicochemical properties and structural features of a molecule. Accordingly, the combined interactions of an analyte and the mobile phase used is still an area that demands further clarifications since there is no general pattern regarding the nature of a molecule and the mechanism by which vapor-phase ions are produced.

Methods: A multivariate analysis method, such as Partial Least Squares (PLS), provides the opportunity to correlate the effect of a large number of parameters interpreting this complex procedure with the use of appropriate mathematical algorithms.

Negative electrospray ionization mode in mass spectrometry: A new perspective via modeling.

Electrospray ionization technique is used for production of gas phase ions without fragmentation and is considered as one of the most sensitive analytical methods for structural characterization of molecules. Nonetheless, the determination of some parameters (physicochemical properties or structural features) that may enhance the signal response especially in the negative ion mode has not yet been clarified. The present work is an attempt to correlate the signal response behavior of 110 compounds used as probes, with their characteristics (molecular descriptors, X variables).

Modeling the drugs' passive transfer in the body based on their chromatographic behavior.

One of the most challenging aims in modern analytical chemistry and pharmaceutical analysis is to create models for drugs' behavior based on simulation experiments. Since drugs' effects are closely related to their molecular properties, numerous characteristics of drugs are used in order to acquire a model of passive absorption and transfer in the human body. Importantly, such direction in innovative bioanalytical methodologies is also of stressful need in the area of personalized medicine to implement nanotechnological and genomics advancements.

Elucidation of the retention mechanism on a reverse-phase cyano column by modeling.

Partial least squares and quantitative structure-retention relationship models have been used mainly to explain and then to predict the retention mechanism on a cyanopropyl high-performance liquid chromatography column. Developing and applying the models involves studying the chromatographic behavior of 100 probes. Characterization of the probes took place under optimized isocratic conditions at variable proportions of two mobile phase mixtures.

Study and development of reversed-phase HPLC systems for the determination of 2-imidazolines in the presence of preservatives in pharmaceutical preparations.

Different HPLC chromatographic systems were investigated on a C18 ACE 5 pm, 150 x 4.6 mm id column for the determination of tymazoline, tramazoline, and antazoline, with either naphazoline or xylometazoline, in commercial preparations. For the development and optimization of the systems, a Response Surface Method (r=0.

Modelling by partial least squares the relationship between the HPLC mobile phases and analytes on phenyl column.

Twenty-five descriptors and 61 structurally different analytes have been used on a partial least squares (PLS) to latent structure technique in order to study chromatographically their interaction mechanism on a phenyl column. According to the model, 240 different retention times of the analytes, expressed as Y variable (log k), at different % MeOH mobile-phase concentrations have been correlated with their theoretical most important structural or molecular descriptors. The goodness-of-fit was estimated by the coefficient of multiple determinations r(2) (0.

Synthesis and anti-inflammatory activity of chalcones and related Mannich bases.

Chalcones and Mannich bases have been reported to present antiinflammatory activities as well as inhibitory activities on several factors implicated in inflammation disorders. A series of chalcones and some related Mannich bases were prepared by Claisen-Schmidt condensation of appropriate acetophenones with appropriate aromatic aldehyde. Mannich bases were derived from chalcones, with formaldehyde and the corresponding amine.