Mass defect profiles of biological matrices and the general applicability of mass defect filtering for metabolite detection.

Recent examples have demonstrated that the high-resolution liquid chromatography/mass spectrometry (LC/MS)-based mass defect filtering (MDF) technique was effective in selectively detecting drug metabolites regardless of their molecular weights or fragmentation patterns. The main objective of the current study was to evaluate the general applicability of MDF for drug metabolite detection in typical biological matrices. Mass defect profiles of commonly used biological matrices including plasma, urine, bile, and feces were obtained using an LTQ FT mass spectrometer and were compared with those of 115 commonly prescribed drugs. The mass defect profiles were presented as two-dimensional Y-X plots with the determined mass defects of components on the y-axis versus the corresponding m/z values on the x-axis. The mass defect profiles of the matrices appeared to be similar for each type of matrix across species, yet marked differences were apparent between matrices of a given species. The mass defect profiles of components in plasma, bile, and feces showed significant separation from most of the 115 drugs. The mass defect profiles of urine did not show such clean separation from that of the 115 drugs. The results suggest that MDF has a broad applicability for selective detection of drug metabolites in plasma, bile and feces although the selectivity for detecting urinary drug metabolites is not as good as in the other matrices. In addition, the mass defect profiles of the biological matrices allow for prediction of the effectiveness of MDF for certain applications, and for designing specific MDF windows for selective detection of drug metabolites.

[Clinical significance of assessment of the metabolism of connective-tissue biopolymers in patients with type 1 diabetes mellitus and with diabetic nephropathy]. / Klinicheskoe znachenie otsenki obmena biopolimerov soedinitel'noi tkani u bol'nykh sakharnym diabetom tipa 1 s diabeticheskoi nefropatiei.

The purpose of the case study was to define a degree of destructive changes in the connective tissue at different stages of diabetic nephropathy (DN) progression. One hundred and twenty eight DN patients with type 1 diabetes mellitus, disease duration-5 to 20 years (classification according C. Mogensen, 1983) were examined. Special biochemical tools were used to evaluate the connective-tissue condition. The parameters of metabolism of the connective-tissue biopolymers were investigated in blood, urea and saliva, i.e. general and sulphated glucosamine glycine (GAG), sialic acid (SA) and oxyproline fractions. The results showed an increasing value of total and sulphated GAG and SA with a worsening DN severity, which is indicative of a destruction degree of glycoprotein-complexes in the microvascular basal membranes. A high level of bound oxyproline fractions denotes the fibril-genesis processes, which start to activate yet at the preclinical DN stage. The changes detected previously in the parameters of metabolism of the connective-tissue biopolymers, as observed in DN patients, ensure a timely choice of a therapy and a proper monitoring of its efficiency.

[Biopolymers in urine of patients with syringomyelia]. / Biopolimery mochi bol'nykh siringomieliei.

Urine of patients with syringomyelia was analysed by gel filtration, ion-exchange chromatography and analytical chemistry methods. Increased level of acidic glycoproteins and decreased level glycosaminoglycans levels were found. Patients with syringomyelia had smaller glycosaminoglycans components of proteoglycans than normal subjects.

The evidence for conjugated mandelic and phenylglyoxylic acids in the urine of rats dosed with styrene.

Male Wistar rats were dosed intraperitoneally with styrene (400 mg/kg). Urine samples were collected over phosphate buffer, pH 6.5 for 24 h. Excretion of mandelic (MA) and phenylglyoxylic acid (PGA) amounted to 1.66 +/- 0.62 and 5.21 +/- 2.44% of dose, respectively, as determined by ion-pair HPLC. After acidic hydrolysis, the amount of MA and PGA found in urine increased to 2.10 +/- 0.84 and 6.81 +/- 3.20% (mean +/- S.D.; n = 7), respectively. A similar increase was observed after alkaline hydrolysis of urine samples. Differences between hydrolysed and non-hydrolysed samples were significant in the paired t-test (P < 0.05). Further, urine samples were fractionated by HPLC. Fractions were subjected to acidic hydrolysis and analysed by HPLC and GC/MS. Both MA and PGA were detected in the fraction which did not contain any of these metabolites before hydrolytic treatment. Thus, MA and PGA, which are used as biomarkers of exposure to styrene, form hydrolysable conjugates in the rat. At least a minor part of the total urinary MA and PGA is bound in these conjugates.