L. De Angelis

Postmortem Changes of Normetanephrine Determined by a Mass‐Fragmentographic Technique in Different Rat Brain Areas

Abstract: A specific and sensitive gas chromatographic–mass spectrometric assay for measurement of normetanephrine (NMN) in different rat brain regions is presented. The results show that hypothalamus contains the highest concentrations of the norepinephrine metabolite. An increase of NMN concentrations has been detected in animals killed by decapitation in comparison with microwave–irradiated rats. This finding has to be taken into consideration when NMN is measured in the brain in order to assess the functional activity of noradrenergic neurons.

A simple approach to study the effect of haloperidol on GABA functional activity in the nigro-striatal system

T H ~ STKIATUM contains a number of small GABAergjc interneurons as well as GABAergic neurons with axons connecting the basal ganglia to the zona reticulata of substantia nigra (FONNUM ef ul., 1974; MCGEER et al., 1971). FONNUM er ul. (1974) have reported a decrease of glutamate decarboxylase (EC 4.1.1.15) in substantia nigra following caudate lesions. suggesting that the primary source of GAD and GABA in substantia nigra is the well-known striwnigral pathway. The only important inhibitory afferent to the striatum is the dopaminergic nigr-striatal pathway (UNGERSTEDT. 1971). The elucidation of the mutual regulation among dopaminergic and GABAergic neurons in striatum and suhstantia nigra might help to explain the mechanism of feedback (activation or inhibition) of a Hamilton microsyringe via a needle with a stop so that it could penetrate to a depth of 4 to 4.5 mm. After recovery from the anaesthesia the animals were allowed food and water ad lib. The rats were killed by exposing the skull for 3 4 s to a beam of high energy microwave radiations. (Microwave oven of 2.0 kW. 2.45 GHL 75 W/cm2, Med. Eng. Consult.. U.S.A.. see GUIWTTI er ol., 1974). This procedure completely inactivates the enzymes involved in the biosynthesis of GABA, thus avoiding the postmortem increase of the neurotransmitter concentrations (CATTABENI er a/.. 1975). GABA was determined with a mass fragmentographic method recently described (CATTABENI et a/.. 1976).

Measurement of relative amounts of phospho‐ and dephospho‐B‐50(GAP‐43) peptides by fast atom bombardment‐mass spectrometry

The biological role of phosphoproteins depends upon their degree of phosphorylation in vivo. Methods currently available to measure the degree of phosphorylation of a protein involve indirect procedures to detect the 32P‐phosphate incorporation. We report here a direct method to measure relative amounts of phospho‐ and dephospho‐forms of peptides based upon a mass spectrometric technique. The intensities of the molecular ions corresponding to the two forms of the peptides are proportional to their relative amounts. This is demonstrated for a peptide fragment of the protein B‐5O(GAP‐43) and for kemptide, respectively substrates for protein kinases C and A, and demonstrates the applicability of fast atom bombardment‐mass spectrometry to quantitate peptides bearing post‐translational modifications.

Adolescents and young adults with type 1 diabetes display a high prevalence of endothelial dysfunction

Little is known about endothelial function in adolescents with type 1 diabetes, and we evaluated endothelial dysfunction, using reactive hyperaemia peripheral arterial tonometry (RH‐PAT).

Liquid chromatographic determination of imazosulfuron in drinking water and in soil using ultraviolet detection.

Reversed-phase liquid chromatography (LC) is used to determine a relatively new sulfonylureic herbicide, imazosulfuron, 1-(2-chloroimidazo-[1,2-a] pyridin-3-ylsulfonyl)-3-(4,6-dimethoxy-2-pyrimidinyl)-urea (TH-913), in drinking water and in soil. TH-913 is extracted from water using solid-phase extraction on C18 bonded silica. Soil samples (20 g) are extracted with 300 ml of methanol-water (50:50) and the acidified extracts are transferred onto Sep-Pak C18 and processed as described for water samples. Off-line desorption is done with 20 ml of methanol-water (50:50). The eluate is evaporated to dryness, the residue dissolved in acetonitrile and analysed by LC with UV detection at 238 nm. The recoveries of TH-913 from water were over 95% (at 0.05 microg/l level) and from soil over 90% (at 0.005 mg/kg level).

Pharmacokinetics of Sobrerol in chronic bronchitis

SummaryThe pharmacokinetic profile of Sobrerol, a mucolytic drug, has been studied in patients with acute exacerbations of chronic bronchitis and dense sputum. In addition to measurement of serum and urine levels, the concentration in bronchial mucus was also examined, and their correlation was calculated. Mass fragmentographic analysis was used to assay free sobrerol and its principal urinary metabolites hydrated carvone and glucuronidated sobrerol. After the doses and administration routes used, there appeared to be accumulation of sobrerol in bronchial mucus. This is a feature of great interest and value for a drug which has the specific action of liquefying mucus.

Bovine seminal plasma contains factors that enhance lymphocyte transformation in vitro.

The important immunosuppressive properties of seminal plasma have significant functions in the processes of reproduction. They mask the presence of an immunostimulating activity. From bovine seminal plasma two active factors have been isolated and characterized with marked enhancing activity for in vitro PHA-dependent lymphocyte transformation. They have inosine and hypoxanthine structures, as confirmed by UV absorption profiles, TLC, mass spectrometry, HPLC patterns, behavior to enzymatic treatments, and breaking of purine ring after acid treatment. Nevertheless, their biological activities are about two orders of magnitude higher than those of commercially available inosine and hypoxanthine standards. Biological activities became practically identical when these were processed (HPLC) in the same way as native molecules. A study to explain such a discrepancy is in progress.