Henoch-Schönlein purpura nephritis and IgA nephropathy: a comparative clinical study.

OBJECTIVES: Henoch-Schönlein purpura nephritis (HSPN) and IgA nephropathy (IgAN) are related syndromes. In the present study we aimed to compare the clinical characteristics and outcome of a large and unselected series of patients diagnosed as having HSPN and IgAN. METHODS: Comparative study of a wide and unselected population of HSPN (142 patient) and IgAN (61 patients) from a teaching hospital of Northern Spain. RESULTS: All of the following comparisons were expressed between HSPN vs. IgAN, respectively. HSPN patients were younger (30.6±26.4 vs. 37.1±16.5 years, p<0.001). Precipitating events, usually an upper respiratory tract infection and/or drug intake, were more frequently observed in HSPN (38% vs. 23%, p=0.03). Extra-renal manifestations were also more common in HSPN than in IgAN; skin lesions (100% vs. 1.8%; p<0.001), gastrointestinal (62% vs. 7.4%; p<0.001), and joint involvement (61.3% vs. 3.6%; p<0.001). However, nephritis was less severe in HSPN, renal insufficiency (25% in HSPN vs. 63.4% in IgAN; p<0.001), nephrotic syndrome (12.5%, vs. 43.7%; p<0.001), and nephritic syndrome (6.8% vs. 10.7%; NS). Leukocytosis was more frequent in HSPN (22.5% vs. 8.2%; p=0.015) and anaemia in IgAN (12.7% in HSPN vs. 36% in IgAN, p<0.001). The frequency of corticosteroid (79.6% vs. 69%; NS) and cytotoxic drug (19% vs. 16.5%, NS) use was similar. The frequency of relapses was similar (38.6% in HSPN vs. 36.3% in IgAN). After a median follow-up of 120.8 (IQR; 110-132) months in HSPN and 138.6 (IQR; 117-156) in IgAN, requirement for dialysis (2.9% vs. 43.5%; p<0.001), renal transplant (0% vs. 36%, p<0.001) and residual chronic renal insufficiency (4.9% vs. 63.8%; p<0.001) was more frequently observed in patients with in IgAN. CONCLUSIONS: HSPN and IgAN represent different syndromes. IgAN has more severe renal involvement while HSPN is associated with more extra-renal manifestations.

Determination of drug levels in human serum by circular dichroism.

A study of the applicability of circular dichroism (CD) for the determination of drug levels in human serum is described and a new method for the quantitative determination of optically active absorbing drugs having Cotton effects at wavelengths about 250 nm in human serum and/or plasma is proposed. The principal advantages of this method are speed, economy, and simplicity, no derivatization or chromatographic separation steps being needed. The validity of the CD determination was confirmed by analysis of variance, beta-lactam antibiotics being chosen as model drugs. In addition, the validation studies performed confirm the accuracy and precision of the proposed method. For beta-lactam antibiotics lacking Cotton effects above 250 nm, an alternative method based on the extraction of the drug from serum is considered.

Direct quantitative determination of optically active absorbing drugs in human urine by circular dichroism. Simultaneous direct determination of beta-lactam antibiotics and proteins.

Over 200 urine samples from 61 subjects were analyzed by circular dichroism spectroscopy. The results proved that this technique can be applied to the direct determination of optically active absorbing drugs in urine of subjects under multiple drug administration, independently of the presence of proteins, which can simultaneously be determined. A list of noninterfering drugs is included. The validity of the present method was confirmed by analysis of variance, the beta-lactam antibiotics ampicillin, cefoxitin, and cephalexin being chosen as model drugs and human albumin as the analytical standard for protein determination. The results demonstrated that the proposed method is accurate and precise, the correlation coefficients being higher than 0.9996. A circular dichroism and HPLC data comparison was successfully performed. The principal advantages of this method are simplicity, quickness, and economy, no derivatization or chromatographic separation steps being needed.

Discrimination and direct determination of cephalosporins by circular dichroism.

The circular dichroism and ultraviolet spectra of 15 commercial cephalosporins in common clinical use are analyzed. Distinguishing between the beta-lactam antibiotics (penicillins, cephalosporins, and cephamycins) on the basis of their CD spectral data has been found to be straightforward. Furthermore, sufficient CD spectral dissimilarities are observed to discriminate among the cephalosporin homologues and to classify these antibiotics in five spectroscopic groups, on the basis of the wavelengths of their Cotton effects. In addition, some chemical structural characteristics for these spectroscopic groups are discussed. Besides molar absorptivity and CD data, the slopes and the intercepts of the equations of the regression line are calculated for each of these antibiotics, the correlation coefficients being higher than 0.9993. The validity of the proposed model is confirmed by analysis of the variance. The results demonstrated that the proposed method is accurate and precise. The method was successfully applied to the direct determination of these drugs in commercial oral suspensions, injections, and capsules. The principal advantages of this method are quickness and simplicity no derivatization or chromatographic separation steps being needed.