Cell-free DNA in the peritoneal effluent of peritoneal dialysis solutions.

The beneficial effects of novel peritoneal dialysis solutions low in glucose degradation products regarding peritoneal cell apoptosis and necrosis are well established in vitro, however in vivo data is lacking. Cell-free DNA quantification is a possible method to determine cell damage through apoptosis and necrosis in vivo. We performed a prospective, cross-over study on 26 stable continuous ambulatory peritoneal dialysis (CAPD) patients, treating each patient for 3 months in a randomized order with a conventional, lactate-buffered, acidic solution (solution D) and a novel, bicarbonate/lactate-buffered neutral solution (solution P). The timed overnight peritoneal effluent was sampled for cell-free DNA quantification using a fluorometric assay. The effluent samples of eighteen patients were finally available for DNA quantification. The concentration range of cell-free DNA in the peritoneal effluents was 1.8-9.5 microg/L. The coefficient of intrapatient variation in overnight effluent cell-free DNA appearance was 15.6 +/- 12.4%. Cell-free DNA peritoneal appearance using solutions D and P was 14.9 +/- 6.8 microg and 11.8 +/- 3.4 microg, respectively (P = 0.02), with the average difference of 3.1 microg (95% CI, 0.7-5.6 microg). Our results show that cell-free DNA is present in the overnight peritoneal effluent of stable CAPD patients. A significant decrease in the cell-free DNA appearance with solution P was found; however, before accepting this as an indicator of a more biocompatible profile causing less peritoneal membrane cell necrosis and apoptosis, confirmatory data on larger patient samples are needed. Our results indicate the potential future role of cell-free DNA in the diagnosis and prognosis of therapy-related peritoneal membrane degeneration.

Positive correlation between galactose-1-phosphate uridyltransferase (GALT) and UDP-galactose-4'-epimerase (GALE) activities.

OBJECTIVES: The aim of our study was to determine whether the activities of galactose-1-phosphate uridyltransferase and UDP-galactose-4'-epimerase are correlated, and in what way they may influence one another. DESIGN AND METHODS: Enzyme activities were measured in red blood cells from 214 individuals. RESULTS: A statistically significant (p<0.001) positive correlation was observed between GALT and GALE activities. CONCLUSIONS: Our results suggest that GALT and GALE activities are correlated and that GALE activity has a greater impact on GALT activity than vice versa.

Optimization of purification of human cell-free mRNA from plasma.

Cell-free RNA has a potential for diagnosis and prognosis of many diseases. Our aim was to optimize a commercially available QIAamp UltraSens Virus Kit (Qiagen, Hilden, Germany) for isolation of mRNA from human plasma. The amount of carrier RNA to bind plasma mRNA, the centrifugal force to pellet the mRNA-carrier RNA complex, the incubation time for proteolysis, and the centrifugal force to bind mRNA to the silica gel membrane were modified in order to maximize the yield of isolated mRNA. The isolated cell-free mRNA was detected for cycA using TaqMan real-time quantitative RT-PCR. The lowest threshold cycle (Ct) was obtained with the use of 4.0 microL of carrier RNA. Pelleting with a centrifugal force of 1500 xg yielded the lowest Ct, but caused difficulties in resuspending the pellet. Therefore, we suggest using a lower centrifugal force of 1300 xg. The duration of proteolysis had no effect on Ct. To bind mRNA to the silica gel membrane, a centrifugal force of 5000 xg is recommended. Our results show that the UltraSens Virus Kit is an appropriate choice for isolating mRNA from human plasma, with imprecision expressed as coefficient of variation below 2%.

Synergistic effect of high lactase activity genotype and galactose-1-phosphate uridyl transferase (GALT) mutations on idiopathic presenile cataract formation.

OBJECTIVES: To evaluate the possible synergistic role of partial galactose metabolism defects, high lactase (LPH) genotype and lactose and galactose ingestion in presenile cataract formation. DESIGN AND METHODS: 51 patients with idiopathic presenile cataracts and 172 healthy cataract-free subjects were genotyped to determine their galactose-1-phosphate uridyl transferase (GALT) and LPH status. Whole milk, skimmed milk and yoghurt consumption was recorded in 19 cataract patients and 172 controls by questionnaire. RESULTS: GALT mutations and whole milk consumption increased the risk of cataract formation in high LPH genotype group, but not in lactose intolerant subjects. Logistic regression analysis showed the synergistic effect of GALT and LPH mutations on cataract formation. CONCLUSIONS: High lactase activity genotypes and mutations in galactose-1-phosphate uridyl transferase have a synergistic effect on presenile cataract formation.

Higher frequency of the galactose-1-phosphate uridyl transferase gene K285N mutation in the Slovenian population.

OBJECTIVES: To analyze a healthy Slovenian population for the frequency of the classical galactosemia allele K285N. DESIGN AND METHODS: DNA was analyzed by means of polymerase chain reaction and restriction fragment length polymorphism. RESULTS: The allele frequency of the K285N mutation in Slovenian population is 0.29%. CONCLUSIONS: The allele frequency of the K285N mutation in Slovenian population is higher than in other Caucasian populations. K285N is one of the most frequent classical galactosemia mutations in the Slovenian population.

UGT1A1(TA)n promoter polymorphism--a new case of a (TA)8 allele in Caucasians.

Gilbert's syndrome is a mild hereditary unconjugated hyperbilirubinemia caused by mutations in the bilirubin UDP-glucuronosyltransferase gene (UGT1A1). The causative mutation in Caucasians is almost exclusively a TA dinucleotide insertion in the TATA box of the UGT1A1 promoter. Affected individuals are homozygous for the variant promoter and have 7 instead of 6 TA repeats. The aim of the present study was to determine the genotypes of UGT1A1(TA)n promoter polymorphism in the healthy Slovenian population and to investigate the association of genotypes with serum bilirubin levels. 236 healthy subjects were genotyped by single-strand conformation polymorphism analysis, which was validated by sequence analysis. The frequencies of genotypes were as follows: (TA)(6/6) (38.1%), (TA)(6/7) (47.9%), (TA)(7/7) (13.6%). There was a statistically significant association of genotypes with serum bilirubin levels (p<0.001). Subjects with genotype (TA)(7/7) had the highest and subjects with genotype (TA)(6/6) the lowest total serum bilirubin levels. One individual in the group had the rare genotype (TA)(7/8) (0.4%). Analysis of his family showed the following genotypes: (TA)(6/8) in his father and sister and (TA)(7/8) in his two brothers. In conclusion, the frequency of UGT1A1(TA)n promoter polymorphism genotypes was determined for the first time in the Slovenian population and is similar to frequencies observed in other Caucasian populations. The extremely rare (TA)8 allele in Caucasians was found also in Slovenians.

Oxidative stress assays for disease risk stratification.

Despite the fact that oxidative stress is a significant aetiological factor in several degenerative diseases, its measurement is rarely a part of "routine analyses" performed in hospital clinical chemistry laboratories. This situation is likely to change, as interest in this topic is increasing rapidly. Here we review the pertinent literature, with an assessment of assays for oxidative stress, and categorize them under: (i) assays for monitoring lipid peroxidation, (ii) assays for measuring oxidized amino acids, (iii) assays for measuring oxidized nucleic acids, (iv) assays based on physicochemical and immunological properties of oxidized low-density lipoprotein, and (v) assays for measuring the antioxidant capacity of body fluids and tissues. Our overview should be of help when choosing appropriate laboratory assays for oxidative stress and for routine disease risk stratification.

Paraoxonase/arylesterase in serum of patients with type II diabetes mellitus.

The aim of this study was to determine whether the paraoxonase (PON1) status, i.e. PON1 activities and phenotypes (AA, AB and BB), and its relationship with lipid status are different in patients with type II diabetes as compared to healthy population. Diabetic group comprised 175 patients with type II diabetes mellitus (94 men and 81 women) who came to their regular control examination and took the oral glucose tolerance test. Patients with type II diabetes mellitus diagnosis for 12 years on average were on peroral antidiabetics, or insulin or diet, and 3 patients had no therapy prescribed yet. Control group comprised 114 apparently healthy individuals (28 men and 86 women) who were not on any medication. The paraoxonase activity was measured with 2.0 mmol L(-1) paraoxon in the absence and in the presence of 1.0 mol L(-1) NaCl, and with 2.0 mmol L(-1) phenylacetate. Both activities were measured spectrophotometrically at 37 degrees C in 0.1 mol L(-1) Tris-HCl buffer, pH = 8.0, containing 2.0 mmol L(-1) CaCl(2). Sera of diabetic and control subjects were assigned to the paraoxonase phenotypes on the basis of the basal paraoxonase activity distribution. We assigned 45% sera of male and 49% sera of female diabetic patients, and 64% sera of both genders of the control group to the AA low activity phenotype. There were no differences in paraoxonase activities between the gender- and phenotype-matched diabetic and control groups. Enzyme activity against the phenylacetate was higher, and phenotype-dependent, only in diabetic patients. In contrast to AA phenotype individuals, total cholesterol and LDL-cholesterol in the female diabetic group and triglyceride concentration in the male diabetic group assigned to pooled AB and BB phenotypes were higher than in the corresponding controls. It follows from PON1 phenotype distribution that less antiatherogenic paraoxonase B allele is more frequent in type II diabetes mellitus than in the healthy population. Their lipid status is more atherogenic, which could indicate a risk of premature atherosclerosis.

Galactose-1-phosphate uridyl transferase gene mutations in women with premature ovarian failure.

We determined the frequency of galactose-1-phosphate uridyl transferase gene mutations: Q188R, K285N, and the Duarte allelle in 86 patients with idiopathic premature ovarian failure (POF) and 95 controls. No association of the mutations with POF was found.

Q188R, K285N, and N314D mutation-associated alleles in the galactose-1-phosphate uridyltransferase gene and female infertility.

In a retrospective case-control study, the frequencies of Q188R, K285N, N314D, and IVS5-24G>A mutations were determined with the use of polymerase chain reaction and restriction fragment length polymorphism in the group of infertile women and the controls. No statistically significant differences were observed in the allele frequencies between the infertile women and control groups.

Relationship between the sialic acid content of low-density lipoprotein (LDL) and autoantibodies to oxidized LDL in the plasma of healthy subjects and patients with atherosclerosis.

To determine whether the sialic acid (SA) content of the low-density lipoprotein (LDL) is related to the plasma concentration of autoantibodies to oxidized LDL (oxLDL), we measured the SA content of LDL and the concentrations of oxLDL and autoantibodies to oxLDL in plasma of 20 apparently healthy subjects and 20 patients with advanced coronary atherosclerosis. In the healthy subjects the SA content of LDL correlated positively with plasma concentration of autoantibodies to oxLDL. In agreement with the literature the decreased SA content of LDL was associated with an increased fraction of oxLDL; a decreased fraction of oxLDL was associated with an increased plasma concentration of autoantibodies to oxLDL. In the patients the SA content of LDL and plasma concentrations of oxLDL and autoantibodies to oxLDL were not related. We conclude that the SA content of LDL correlates positively with plasma concentration of autoantibodies to oxLDL in healthy subjects. However, this association may vary depending on the stage of atherogenesis. Although our results suggest dependence of LDL SA content on the clearance of oxidatively modified (desialylated and oxidized) LDL from blood by autoantibodies to oxLDL, the mechanisms regulating the SA content of LDL await further studies.

Frequencies of Q188R and N314D mutations and IVS5-24g>A intron variation in the galactose-1-phosphate uridyl transferase (GALT) gene in the Slovenian population.

Numerous mutations in the galactose-1-phosphate uridyl transferase (GALT) gene have been found to impair GALT activity to different extent, causing galactosemia. This disorder exhibits considerable allelic heterogeneity in different populations and ethnic groups. The Q188R mutation accounts for 60-70% of classical galactosemia alleles in the Caucasian population. Individuals homoallelic for Q188R have a severe phenotype with complete loss of enzyme activity. Another form of GALT deficiency is Duarte galactosemia with N314D mutation associated alleles (Duarte-2). Although heterozygotes for classical galactosemia are asymptomatic at birth and Duarte galactosemia appears to be quite benign, there are some indications that these disorders can increase the risk of developing certain diseases later in life. The aim of our study was to analyze a healthy Slovenian population for the frequencies of Q188R and N314D mutations, and for the Duarte-2 indicative intronic variation IVS5-24G>A. DNA samples from 174 healthy subjects were analyzed for all three mutations by polymerase chain reaction and digestion with restriction enzymes. Allele frequencies for Q188R and N314D mutations and IVS5-24G>A intron variation were found to be 0.29%, 8.0% and 5.7%, respectively. These results correlate well with those reported for most other healthy Caucasian populations.