Search results for "Urine"

Bidirectional Control between Cholesterol Shuttle and Purine Signal at the Central Nervous System.

2022

Recent studies have highlighted the mechanisms controlling the formation of cerebral cholesterol, which is synthesized in situ primarily by astrocytes, where it is loaded onto apolipoproteins and delivered to neurons and oligodendrocytes through interactions with specific lipoprotein receptors. The “cholesterol shuttle” is influenced by numerous proteins or carbohydrates, which mainly modulate the lipoprotein receptor activity, function and signaling. These molecules, provided with enzymatic/proteolytic activity leading to the formation of peptide fragments of different sizes and specific sequences, could be also responsible for machinery malfunctions, which are associated with neurological…

Dioniso a Centuripe: iconografia ‘teatrale’ e imagerie dionisiaca in contesto funerario

2021

The purpose of the paper is to bring together and to assess some strands of the funerary imagery elaborated in Centuripe (Sicily) in 3rd-1st centuries B.C., that until recently have been viewed in total isolation from each other. Dionysian themes and motifs have been variously identified in the local polychrome pottery, since the discovery, early in 20th century, of two impressive vases representing Dionysos himself in a relaxed pose; as opposed to the prevailing “bacchic-orphic” explanation, however, from the second half of past century the nuptial theme was considered to be the most important of the Centuripan vase inventory; finally, some scholars have argued that the repertory was not s…

Synthetic Strategies Towards O6-Substituted Guanine Derivatives and their Application in Medicine

2005

Determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin in goat milk and tissues by glass capillary gas chromatography and medium resolution mass fragme…

1981

Abstract An analytical method has been developed for the study of the elimination of 2,3,7,8-tetrachlodoribenzo-p-dioxin (TCDD) by lactation and its determination in various tissues of goat. The method is based on the alkaline hydrolysis of milk, liver, fat, muscle, blood, faeces and urine samples, extraction with n-hexane, treatment with sulphuric acid-saturated silica gel, chromatographic clean-up on silica gel and alumina micro-columns, and glass capillary gas chromatography—medium resolution mass fragmenography (resolution 2000). 1,2,3,4-Tetrachlorodibenzo-p-dioxin is used as the internal standard, the concentration of TCDD being determined from the calibration curve calculated from the…

On-line Chloride Interference Removal for Arsenic Determination in Waste Water and Urine by ICP-MS Using a Modified Capillary

2002

The determination of arsenic in environmental samples like waste waters from industrial effluents and in biological samples like urine is very important due to the toxic nature of some of its species at moderate levels of exposure. The objective of this study was to evaluate the capability of modified anionic capillaries to remove chloride for ICP-MS determination of arsenic, which causes spectral interference due to formation of 40 Ar 35 Cl + . Also high chloride content gives non-spectral interferences. The results indicate that arsenic at a concentration higher than 1 µg L m 1 in a matrix with a chloride content up to 600 mg L m 1 can be accurately determined using a 3-aminopropyltrimeth…

Heteroditopic chemosensor to detect γ-hydroxybutyric acid (GHB) in soft drinks and alcoholic beverages.

2021

Drug-Facilitated Sexual Assault (DFSA) is a problem of considerable dimensions on a global scale. Among the different compounds used in DFSA assaults, 4-hydroxybutyric acid (GHB) is one of the most elusive due to its physical and biological characteristics. Therefore, the development of real-time detection methods to detect GHB not only in drinks but also in urine is very important for personal and social security. Here, we report two new heteroditopic chemosensors capable of recognizing and detecting GHB in soft drinks, alcoholic beverages and synthetic urine. The compounds have two moieties: a trifluoroacetyl group and a thiourea, which are able to interact respectively with the hydroxyl …

Die quantitative Bestimmung der p-Oxyphenylbrenztraubens�ure im Harn

1950

Es wird ein Verfahren zur quantitativen Bestimmung der p-Oxyphenylbrenztraubensaure im Harn beschrieben, das auf der Reduktion der p-Oxyphenylbrenztraubensaure zur p-Oxyphenylmilchsaure beruht. Die Methode gestattet den spezifischen Nachweis der im Harn ausgeschiedenen p-Oxyphenylbrenztraubensaure und ist geeignet, die Leberfunktionsprobe nachFelix undTeske wesentlich zu vereinfachen.

53 Human bio-monitoring of epoxy resins and hardeners in the production of rotor: blades

2018

Introduction In a small company producing rotor blades for aviation from carbon composites, epoxy resins based on Novolac and isophorone diamine as hardener are used. Both compounds can be absorbed via skin contact and were shown to be strong skin sensitizers. As a part of risk assessment, the industrial physician prompted a biological monitoring to determine the internal exposure of the workers. Methods 6 workers were identified with potential contact to the hardener and resin. We have collected pre- and post-shift urine samples at the beginning and mid of the work week and analysed them for the concentration of isophoronediamine and bisphenol-f-diglycidylethermetabolites as biomarker for …

Determination of theophylline and paraxanthine in urine samples by liquid chromatography using the H-point standard additions method

1992

Abstract The simultaneous determination of theophylline and paraxanthine in urine samples by the H-point standard additions method (HPSAM) is described. Samples are extracted with C 18 solid-phase extraction cartridges and chromatographed using a Hypersil C 18 -ODS column and a mobile phase consisting of acetonirile-phosphate buffer in the gradient elution mode. Under these conditions theophylline and paraxanthine are eluted with short retention times. Although their chromatographic peaks are overlapped and their spectra are very similar, the H-point standard additions method provides excellent results in the determination of both xanthines at therapeutic levels.

Extraktionschromatographische trennung der freien porphyrine auf tri-n-butylphosphat-s?ulen im pH-gradienten

1969

Abstract The method described allows the separation of the free porphyrins on a tri-n-butyl phosphate (TBP) column by elution with a pH gradient. The prophyrins are eluted from the column at discrete pH values (xD) according to the number of carboxyl groups in the side chains. Separation of isomers could not be observed under the conditions used. The xD values indicate the centre of the pH-interval, in which the dissociation of the carboxyl groups occurs. This finding could be confirmed by spectro-photometric measurements. By combining the method proposed with the method of separation by extraction chromatography in the TBP/IN HCl partition system and the thin-layer technique in the 2,6-lut…