Rituximab: active treatment of central nervous system involvement by non-Hodgkin's lymphoma?
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Adult↗
Biomedical subjects
U Amsler
Publications and source records attributed to U Amsler.
Extracranial vertebral artery dissection causing cervical root lesion.
The authors report an unusual manifestation of extracranial vertebral artery dissection (VAD), presenting with a predominantly motor radicular manifestation. Cervical magnetic resonance imaging (MRI) revealed the intramural hematoma in the dissected vessel wall, compressing mainly the segmental motor root and, to a lesser degree, the sensory ganglion. In the digital subtraction angiography (DSA), a circumscribed narrowing of the incriminated vessel was demonstrated. Color-coded Duplex imaging (CDDI) revealed complete recanalization after a few days of anticoagulation treatment. Complete neurologic recovery was seen after 3 months. Considering the MRI data, the likely pathogenetic mechanism was compression of the nerve root by the intramural hematoma. The synopsis with similar cases in the literature points to the characteristic features, i.e., the association of neck pain with radicular motor deficit and the absence of degenerative disk disease. The respective syndrome should raise the suspicion of vertebral artery dissection, especially in young individuals.
Adult↗
Beta-endorphin-like immunoreactivity: assessment of blood levels in patients with tumors of different origin.
Beta-endorphin-like immunoreactivity (beta-ELIR) blood levels in control subjects and in patients with different carcinoma and non-Hodgkin's lymphoma tumor types, were found within the same range, with the exception of one carcinoma type. This pertained to a group of patients with small cell lung cancer who had a significantly higher median beta-ELIR level compared to controls. This finding, and the fact that proopiomelanocortin expression is enhanced in tissues of this cancer type, suggest that the latter might secrete elevated beta-ELIR amounts into the blood of the affected patients.
Female↗
Quantification of N-acetylaspartylglutamate, an N-terminal blocked dipeptide neurotransmitter candidate, in brain slice superfusates by gas chromatography-mass spectrometry.
N-Acetylaspartylglutamate is a highly promising neurotransmitter candidate. A method for its quantification has been developed that allows to investigate its stimulation-induced release from brain slices. The method is based on ion-exchange prepurification, derivatization with HCl in methanol, separation by capillary gas chromatography and quantification by ammonia chemical ionization mass spectrometry with selected-ion monitoring. Deuterium-labelled N-acetylaspartylglutamate is used as internal standard. The method has been validated, also with respect to possible interfering compounds. A limit of quantification in the low pmol to high fmol range has been achieved, which is clearly sufficient for the intended purpose. A detailed analytical procedure is given, and alternatives for some of the different steps are discussed. Derivatization with diazomethane instead of methanolic HCl turned out to be impracticable. The method may well be applicable to certain other N-terminal blocked di- and tripeptides and to acylated amino acids.
Animals↗
Release of N-acetylaspartylglutamate on depolarization of rat brain slices.
In a great number of investigations, evidence in favor of a neurotransmitter role of the N-terminal-blocked, acidic dipeptide N-acetylaspartylglutamate (NAAG) has been accumulating. In fact, in some systems of the mammalian brain, almost all of the classical criteria for neurotransmitters have been fulfilled by NAAG except for the demonstration of its release from nervous tissue on depolarization. For quantification of NAAG in superfusates of brain slices, we have developed an analytical procedure consisting of an ion exchange prepurification, followed by a derivatization procedure and gas chromatography-mass spectrometry with chemical ionization and selected ion monitoring. Deuterated NAAG was used as an internal standard to provide a high degree of reliability for the analytical method. Detection limits of less than 1 pmol were achieved. A statistically highly significant increase of NAAG concentration in superfusates from rat neocortex, piriform cortex/amygdala, and hippocampus on depolarization with 50 mM K+ could be demonstrated and was shown to be largely Ca2+ dependent. These results support the hypothesis that NAAG is a neurotransmitter. Especially with respect to the piriform cortex, the present demonstration of NAAG release is consistent with electrophysiological and immunohistochemical evidence for its neurotransmitter function at terminals of the lateral olfactory tract.
Amygdala↗
Ventricular cerebrospinal fluid concentrations of putative amino acid transmitters in Parkinson's disease and other disorders.
Concentrations of putative neuroactive substances glutamate, aspartate, gamma-aminobutyric acid, glycine, proline and ethanolamine were determined in ventricular cerebrospinal fluid collected in patients suffering from Parkinson's disease, pain syndromes or cerebellar tremor. Values are similar to those given in the literature for lumbar cerebrospinal fluid. A decrease in gamma-aminobutyric acid in Parkinson patients, as reported in lumbar cerebrospinal fluid, could not be observed. Further evidence for a rostro-caudal gradient for gamma-aminobutyric acid is supplied. New insights into pathophysiological mechanisms in any of the investigated syndromes may not be derived.
Adult↗
Identification of quinolinic acid in rat and human brain tissue.
An analytical technique for the determination of the excitotoxic compound quinolinic acid (2,3-pyridine dicarboxylic acid) in brain tissue has been developed. Following sample prepurification by ion exchange and high pressure liquid chromatography, quinolinic acid is converted to the dihexafluoroisopropyl ester and the derivative is analyzed by mass fragmentography. Using the present technique quinolinic acid has been identified in both rat and human brain tissue.
Animals↗
Gas chromatographic method for the determination of trace amounts of putative amino acid neurotransmitters from brain perfusates collected in vivo.
Glass capillary gas chromatography in combination with thermionic detection has been developed for the measurement of trace amounts of glycine, beta-alanine, aspartic acid, gamma-aminobutyric acid and glutamic acid from brain perfusates collected in vivo by push-pull cannula techniques. Amino acids extracted from the dried perfusate residues are converted to the corresponding N-pentafluoropropionyl hexafluoroisopropyl esters (PFP-HFIP derivatives) and separated by gas chromatography on a glass capillary column coated with methylsiloxane. The detection limit of the amino acids (signal-to-noise ratio 3:1) ranges between 200 fmol and 2.0 pmol. The assay was applied to the measurement of amino acids released in vivo in the pigeon optic tectum into perfusates collected by push-pull techniques.
Amino Acids↗
Mass fragmentographic method for the determination of trace amounts of putative amino acid neurotransmitters and related compounds from brain perfusates collected in vivo.
A mass fragmentographic method for the determination of trace amounts of amino acid neurotransmitter candidates from brain perfusates is described. The analytical procedure includes the measurements of glycine, beta-alanine, gamma-aminobutyric acid, proline, aspartic acid, and glutamic acid; alpha-alanine, leucine, and sarcosine, undergoing gas chromatographic coelution, are detected simultaneously. Amino acids extracted from dried perfusate residues are converted to the corresponding N-pentafluoropropionyl hexafluoroisopropyl esters by a single-step procedure. Gas chromatographic separation of the amino acid derivatives is achieved on a packed glass column filled with trifluoropropylsilicone as stationary phase. The limit of detection for the different derivatives (signal-to-noise, 3:1) ranges from 50 femtomol to 1 picomol. Deuterium-labeled amino acid analogues are used as internal standards for quantitative measurements. The mass spectral characteristics of the derivatives are compared and discussed. The technique has been applied to the assay of amino acids released in vivo within the pigeon optic tectum, demonstrating the capabilities of the present analytical approach.
Amino Acids↗
In vivo release of glutamate and aspartate following optic nerve stimulation.
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Animals↗