Significant association between renal function and area of amyloid deposition in kidney biopsy specimens in both AA amyloidosis associated with rheumatoid arthritis and AL amyloidosis.

The kidney is a major target organ for systemic amyloidosis, which results in proteinuria and an elevated serum creatinine level. The clinical manifestations and precursor proteins of amyloid A (AA) and light-chain (AL) amyloidosis are different, and the renal damage due to amyloid deposition also seems to differ. The purpose of this study was to clarify haw the difference in clinical features between AA and AL amyloidosis are explained by the difference in the amount and distribution of amyloid deposition in the renal tissues. A total of 119 patients participated: 58 patients with an established diagnosis of AA amyloidosis (AA group) and 61 with AL amyloidosis (AL group). We retrospectively investigated the correlation between clinical data, pathological manifestations, and the area occupied by amyloid in renal biopsy specimens. In most of the renal specimens the percentage area occupied by amyloid was less than 10%. For statistical analyses, the percentage area of amyloid deposition was transformed to a common logarithmic value (Log10%amyloid). The results of sex-, age-, and Log10%amyloid-adjusted analyses showed that systolic blood pressure (SBP) was higher in the AA group. In terms of renal function parameters, serum creatinine, creatinine clearance (Ccr) and estimated glomerular filtration rate (eGFR) indicated significant renal impairment in the AA group, whereas urinary protein indicated significant renal impairment in the AL group. Pathological examinations revealed amyloid was predominantly deposited at glomerular basement membrane (GBM) and easily transferred to the mesangial area in the AA group, and it was predominantly deposited at in the AL group. The degree of amyloid deposition in the glomerular capillary was significantly more severe in AL group. The frequency of amyloid deposits in extraglomerular mesangium was not significantly different between the two groups, but in AA group, the degree amyloid deposition was significantly more severe, and the deposition pattern in the glomerulus was nodular. Nodular deposition in extraglomerular mesangium leads to renal impairment in AA group. There are significant differences between AA and AL amyloidosis with regard to the renal function, especially in terms of Ccr, eGFR and urinary protein, even after Log10%amyloid was adjusted; showing that these inter-group differences in renal function would not be depend on the amount of renal amyloid deposits. These differences could be explained by the difference in distribution and morphological pattern of amyloid deposition in the renal tissue.

Unique pentafluorobenzylation and collision-induced dissociation for specific and accurate GC-MS/MS quantification of the catecholamine metabolite 3,4-dihydroxyphenylglycol (DHPG) in human urine.

In the human body, the catecholamine norepinephrine is mainly metabolized to 3,4-dihydroxyphenylglycol (DHPG) which therefore serves as an important biomarker for norepinephrine's metabolism. Most data on DHPG concentrations in human plasma and urine has been generated by using HPLC-ECD or GC-MS technologies. Here, we describe a stable-isotope dilution GC-MS/MS method for the quantitative determination of DHPG in human urine using trideutero-DHPG (d(3)-DHPG) as internal standard and a two-step derivatization process with pentafluorobenzyl bromide (PFB-Br) and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). Two pentafluorobenzyl (PFB) trimethylsilyl (TMS) derivatives were obtained and identified, i.e., two isomeric DHPG-PFB-(TMS)(3) derivatives and the later eluting DHPG-tetrafluorobenzyl-(TMS)(2) derivative, i.e., DHPG-TFB-(TMS)(2). To our knowledge the DHPG-TFB-(TMS)(2) derivative and the underlying reaction have not been reported previously. In this reaction both vicinal aromatic hydroxyl groups of DHPG react with PFB-Br to form a heterocyclic seven-membered [1,4]dioxepin compound. The DHPG-TFB-(TMS)(2) derivative was used for quantitative GC-MS/MS analysis in the electron-capturing negative-ion chemical ionization mode by selected-reaction monitoring of m/z 351 from m/z 401 for DHPG and of m/z 352 from m/z 404 for d(3)-DHPG. Validation experiments on human urine samples spiked with DHPG in a narrow (0-33 nM) and a wide range (0-901 nM) revealed high recovery (86-104%) and low imprecision (RSD; 0.01-2.8%). LOD and relative LLOQ (rLLOQ) values of the method for DHPG were determined to be 76 amol and 9.4%, respectively. In urine of 28 patients suffering from chronic inflammatory rheumatic diseases, DHPG was measured at a mean concentration of 238 nM (38.3 µg/g creatinine). The DHPG concentration in the respective control group of 40 healthy subjects was measured to be 328 nM (39.2 µg/g creatinine). Given the unique derivatization reaction and collision-induced dissociation, and the straightforwardness the present method is highly specific, accurate, precise, and should be useful in clinical settings.

Adrenomedullin and total nitrite levels in children with acute rheumatic fever.

OBJECTIVE: To investigate the levels of adrenomedullin (AM) and total nitrite, a stable product of nitric oxide (NO), in children with acute rheumatic fever (ARF). DESIGN AND METHODS: Eleven children with ARF were investigated in comparison with 14 healthy controls. Adrenomedullin was detected by HPLC, while total nitrite was quantitated by the Griess reaction. RESULTS: Plasma urinary AM and total nitrite levels were significantly higher in children with ARF, irrespective of whether they were in the acute or convalescent phase of disease. Plasma AM (pmol/mL) levels were 49.19 +/- 3.23 in the acute phase, 44.52 +/- 4.26 in the convalescent phase, 35.49 +/- 3.43 in controls, and urinary AM excretion (pmol/mg creatinine) was 43.45 +/- 18.40 in the acute phase, 32.38 +/- 15.37 in the convalescent phase, and 24.84 +/- 11.38 in controls. Plasma total nitrite levels (mumol/L) were 75.37 +/- 13.13 in the acute phase, 59.81 +/- 12.78 in the convalescent phase, and 41.09 +/- 10.27 in controls. Urinary total nitrite excretion (mumol/mg creatinine) was 3.82 +/- 1.56 in the acute phase, 2.15 +/- 0.58 in the convalescent phase, and 1.33 +/- 0.61 in controls. The differences were statistically significant for all (P < 0.05). CONCLUSION: This study considered that AM and NO may have a role in the immunoinflammatory process of ARF.

Comparative pharmacokinetics of acetyl salicylic acid and its metabolites in children suffering from autoimmune diseases.

UNLABELLED: The aim of the present study was to compare the effect produced by juvenile rheumatoid arthritis (JRA) or rheumatic fever (RF) on the pharmacokinetics of acetyl salicylic acid (ASA) and its metabolites in children with autoimmune diseases (AD). METHODS: A prospective, open labelled study was performed in 17 children with JRA and 17 with RF who received a single dose of 25 mg ASA/kg orally. The pharmacokinetics of ASA and its metabolites were determined. The blood and urine levels of each salicylate collected during 24 h were measured by HPLC. A group of 15 healthy teenage volunteers was included as a control group. RESULTS: The maximum plasma concentration, half-life time, area under the curve and the amount of salicylates excreted were statistically different between the JRA and the RF groups, as well as between the RF group and the controls, however, there were no significant differences between the JRA group and the controls. CONCLUSIONS: Dosage schemes must be adjusted for JRA patients, since the half life in these patients is longer than in RF patients. However, due to ample variability of pharmacokinetic parameters it is recommended that dose schemes are individualized on the type of autoimmune disease considered.

Serum penicillin concentrations after intramuscular administration of benzathine penicillin G in children with rheumatic fever and controls.

Serum and urine penicillin levels were determined in 11 children with rheumatic fever (RF) who were receiving benzathine penicillin G (BPG) prophylactically every 3 weeks and in 10 children without RF who received the drug for the treatment of other infections. The dose given was 600,000 units for children weighing less than 25 kg and 1,200,000 units for those with a weight above 25 kg. Blood and urine samples were collected from both groups before and on days 7, 14 and 21 after BPG administration. Our results showed that: minimum inhibitory concentrations (MICs) of BPG for group A beta-hemolytic streptococci were 0.02 IU/ml or 0.0125 microgram/ml; intramuscular BPG did not give adequate serum levels to block the growth of group A beta-hemolytic streptococci in approximately 24 and 62% of children included in the study on days 14 and 21 after its administration, respectively; BPG metabolism was similar in both groups and did not depend on the underlying disease; serum and urine levels did not vary according to sex and weight; and there was a small correlation between serum and urine levels.

[The determination of free and bound oxyproline in urine]. / Opredelenie svobodnogo i sviazannogo oksiprolina v moche.

A method of measuring urinary free, peptide- and protein-bound hydroxyproline is suggested. Adults were found to excrete 18 mumol of free, 155 mumol of peptide-bound, and 8 mumol of protein-bound hydroxyproline daily. In children daily urinary levels of free and peptide-bound hydroxyproline were higher. Data are presented on changes in various hydroxyproline forms in pneumonia, rheumatic fever, and hemorrhagic fever with the renal syndrome.

Decreased serum salicylate concentrations in children with rheumatic fever treated with antacid.

To determine if the common practice of giving antacids to patients on salicylate therapy has an effect on serum salicylate concentrations, we gave a widely used antacid, aluminum and magnesium hydroxide, and aspirin concomitantly to three children with rheumatic fever. Urinary pH increased appreciably, and serum salicylate concentrations decreased by 30 to 70 per cent. In five healthy adult volunteers concomitant administration of antacid had no effect on the bioavailability of aspirin. Pharmacokinetic analysis revealed that the antacid-induced decrease of serum salicylate concentrations was due to increased renal clearance of salicylate caused by the rise in urinalry pH.