Serum bile acids and pruritus in hemodialysis patients.

BACKGROUND: Chronic renal failure (CRF) patients usually suffer from pruritus. The pathophysiology of pruritus is still incompletely understood. SUBJECTS, MATERIALS AND METHODS: In this paper we determined serum total bile acids (STBA) in hemodialysis patients with advanced CRF (ACRF) in order to obtain STBA concentration in predialysis, to assess their probable relation among patients with pruritus and in postdialysis using a polysulfone membrane for dialysis. STBA were determined in 49 ACRF patients with chronic hemodialysis and values were compared to 20 control subjects. Hemodialysis patients were divided in two groups: with and without pruritus. In all these patients, month of renal replacement therapy, diabetic patients, dose of dialysis (Kt/V), viral markers, serum creatinine, serum glucose, aspartate and alanine aminotransferase, alkaline phosphatase, hematocrits and albumin were determined. The intensity of itching among pruritic patients was measured by a score system: mild (M), moderate (MO) and severe (S). RESULTS: No significant differences were found in patients with and without pruritus in months of renal replacement therapy, duration of dialysis or dose of dialysis (Kt/V). STBA were determined in all ACRF patients in predialysis and they showed significant differences compared to controls (p < 0.05), however, no differences were observed in the results obtained when control subjects were compared to ACRF patients without pruritus. Also in predialysis, pruritic patients showed significant differences in STBA compared to patients without pruritus (p < 0.001). STBA concentration showed a significant decrease in postdialysis using a polysulfone membrane in ACRF patients with and without pruritus. Finally, correlation with STBA and itch score of pruritus was significant (p < 0.02). CONCLUSION: Hemodialysis patients with ACRF and pruritus showed an increase of STBA in predialysis and a decrease in postdialysis.

Monitoring the purity of a synthetic peptide by capillary electrophoresis: utilization of an on-line preconcentration method for improved separation and detection sensitivity.

To date, there has been a considerable amount of interest and success in the pharmaceutical industry in the discovery of drug targets and diagnostics utilizing peptides. The success of peptide pharmaceuticals has, however, been accompanied by some failures, both prior to entry and in the clinic. Progress has been made in various areas to improve the effectiveness of the final drug product. One major advance has been in the area of peptide synthesis and control of the purity of the peptide of interest. Recent advances in analytical instrumentation, including advances in capillary electrophoresis, have had a great impact on the ability to separate and detect low quantities of impurities and degradation products during the synthesis of a peptide drug. In this work, affinity capillary electrophoresis (ACE) was developed for the identification and characterization of a chemically synthesized peptide fragment of a snake toxin called fasciculin. The affinity capillary electrophoresis technology utilized in this study employed two powerful techniques coupled on-line for the direct and rapid determination of analytes in simple and complex matrices. The first technique, aimed for the nonselective extraction and concentration of one or more analytes of interest, utilizes a solid-phase analyte concentrator device. The second technique, capillary electrophoresis, is used for the high-resolution analytical separation of the purified and concentrated target analyte(s), after elution from an analyte concentrator device. The on-line preconcentration step has proved valuable in terms of improving separation conditions as well as enhancing detection sensitivity values for the peptide fragment with a sensitivity increase ranging from 100- to 10,000-fold. Different types of analyte concentrator devices and a few binding-desorption conditions were tested. Bare and internal-wall-coated fused-silica capillaries were used. Comparative performance with HPLC in terms of selectivity and sensitivity is also discussed.

Development and validation of capillary electrophoresis methods for pharmaceutical dissolution assays.

The determination of active compounds in samples of dissolution tests of oral solid dosage forms based on the USP 23 methods was performed by capillary electrophoresis after the use of solid-phase extraction disks for the preconcentration of drugs. Enrichment factors of 20:1 allowed the determination of betamethasone and ergotamine tartrate at levels of 0.33 microgram/mL and 1.0 microgram/mL, respectively. CE analysis was performed using fused-silica capillaries (35 or 60 cm length x 75 microns i.d.) and the operating conditions consisted of 15 kV applied voltage and UV detection at 254 nm. The background electrolyte was 20-mM phosphate borate buffer, pH 9.0, containing 50 mM of sodium cholate for the separation of betamethasone and 25 mM phosphate buffer, pH 3.0, for ergotamine tartrate. Validation of the methods was also performed. Accuracy and precision of the intraday and interday assays showed comparable results with those obtained by HPLC.

[Detection of Chlamydia trachomatis in children with acute lower respiratory infection]. / Detección de Chlamydia trachomatis en niños con infección respiratoria aguda baja.

BACKGROUND: Diagnosis of respiratory tract infections due to Chlamydia trachomatis in pediatric patients is very important because of its complications and sequelae. The aim of the present study was to evaluate the performance of rapid methods for reading this diagnosis in 111 children with lower acute respiratory disease. MATERIAL AND METHODS: Their nasopharyngeal aspirates were studied for detection of Chlamydia spp. antigens using enzyme immunoassay, indirect immunofluorescence and isolation in cell culture. The presence of respiratory viruses was also investigated for immunofluorescence. RESULTS: Chlamydia spp. were isolated from 16 samples (14.4%) using cell monolayer cultures. They were detected in 22 samples by immunofluorescence (19.8%) and in seven samples by enzyme immunoassay (6.5%). Respiratory viruses were detected in 77 samples (69.4%). Sixty two percent of cell culture positive samples for Chlamydia were also positive for respiratory syncytial virus and 6% were positive for adenovirus. Sensitivity and specificity of immunofluorescence were 37.5% and 83.1% respectively using Chlamydia cell culture as "golden standard". For enzyme immunoassay these percentages were 26 and 96.8% respectively. CONCLUSIONS: The values obtained are not acceptable for recommending these methods for detecting Chlamydia spp. from nasopharyngeal aspirates. It will be necessary to modify these techniques or to develop alternative methods in order to rapidly and easily obtain a diagnosis of respiratory tract infections due to Chlamydia spp.