Urinary D-asparagine level is decreased by the presence of glioblastoma.

Gliomas, particularly glioblastomas (GBMs), pose significant challenges due to their aggressiveness and poor prognosis. Early detection through biomarkers is critical for improving outcomes. This study aimed to identify novel biomarkers for gliomas, particularly GBMs, using chiral amino acid profiling. We used chiral amino acid analysis to measure amino acid L- and D-isomer levels in resected tissues (tumor and non-tumor), blood, and urine from 33 patients with primary gliomas and 24 healthy volunteers. The levels of D-amino acid oxidase (DAO), a D-amino acid-degrading enzyme, were evaluated to investigate the D-amino acid metabolism in brain tissue. The GBM mouse model was created by transplanting GBM cells into the brain to confirm whether gliomas affect blood and urine chiral amino acid profiles. We also assessed whether D-amino acids produced by GBM cells are involved in cell proliferation. D-asparagine (D-Asn) levels were higher and DAO expression was lower in glioma than in non-glioma tissues. Blood and urinary D-Asn levels were lower in patients with GBM than in healthy volunteers (p < 0.001), increasing after GBM removal (p < 0.05). Urinary D-Asn levels differentiated between healthy volunteers and patients with GBM (area under the curve: 0.93, sensitivity: 0.88, specificity: 0.92). GBM mouse model validated the decrease of urinary D-Asn in GBM. GBM cells used D-Asn for cell proliferation. Gliomas induce alterations in chiral amino acid profiles, affecting blood and urine levels. Urinary D-Asn emerges as a promising diagnostic biomarker for gliomas, reflecting tumor presence and severity.

Altered glycosylation is induced in both alpha- and beta-subunits of human chorionic gonadotropin produced by choriocarcinoma.

The two subunits of human chorionic gonadotropin (hCG) purified from the urine of a patient with choriocarcinoma were successfully separated by SDS-polyacrylamide gel electrophoresis. A comparative study of the oligosaccharides released from the two subunits by hydrazinolysis revealed that altered glycosylation occurs in both subunits and possibly at all four asparagine sites of the choriocarcinoma hCG molecule.

Quantitative determination of 4-N-2-acetamido-2-deoxy-beta-D-glucopyranosyl-L-asparagine in the urine of patients with aspartylglycosaminuria by gas-liquid chromatography.

A specific and sensitive method for the quantitative ;determination of glcNAc-Asn in the urine of patients with inherited deficiency of the lysosomal hydrolase N-aspartyl-beta-glucosaminidase is reported. The method is based on GLC assay of GlcNAc-Asn as its methylated derivative and requires 100 microliter of urine. The mean urinary excretion of GlcNAc-Asn in 14 AGU patients was 0.99 mmol/24 hr (range 0.15 to 1.88). Young patients had similar urinary levels of GlcNAc-Asn to those of the older ones when the results were calculated on the basis of creatinine excretion. Mass fragmentographic analysis revealed the presence of minimal amounts of GlcNAc-Asn in normal urine also. In four of the eight normal subjects studied, a rough quantitative estimation was feasible; the urinary output of GlcNAc-Asn in these subjects ranged from approximately 0.001 to 0.01 mmol/24 hr.

Identification of 4-N-2-acetamido-2-deoxy-beta-D-glucopyranosyl-L-asparagine in biological materials by gas chromatography-mass spectrometry.

A specific and sensitive method for the identification of 4-N-2-acetamido-2-deoxy-beta-D-glucopyranosyl-L-asparagine (GlcNAc-Asn) in urine in aspartylglycosaminuria and in hydrolysates of glycoproteins is described. The method involves permethylation of GlcNAc-Asn followed by gas chromatographic-mass spectrometric analysis of the methylated derivative. It can be used to confirm the diagnosis of aspartylglycosaminuria and to assess the excretion of GlcNAc-Asn in urine during various phases of the disease. The presence of an N-acetylglucosaminyl-asparagine type of carbohydrate-peptide linkage in a glycoprotein can be determined by applying the method to the partial acid hydrolysate of a proteolytically digested glycoprotein.