Blood group antigen A on von Willebrand factor is more protective against ADAMTS13 cleavage than antigens B and H.

BACKGROUND: ADAMTS13 specifically cleaves the peptide bond between Y1605 and M1606 within the VWF-A2 domain. OBJECTIVE: The VWF contains ABO(H) blood group antigens, which may influence the susceptibility of VWF to ADAMTS13. METHODS: Using a unique monoclonal antibody recognizing the Y1605 residue, we have developed a sandwich ELISA to analyze the generation of a VWF-DP by ADAMTS13 quantitatively. RESULTS: Production of VWF-DP after exposure to four different degrees of high shear stress was validated in comparison to the reduction in high-molecular-weight multimers using VWF multimer analysis. In analysis of plasma from 259 healthy individuals, plasma levels of VWF antigen (VWF:Ag) were significantly lower in blood group O than in the other groups and were significantly correlated with plasma VWF-DP levels. The ratio between VWF-DP and VWF:Ag was significantly higher in blood group O than in blood groups A and AB. The ratio in blood group B was also significantly higher than those in A and AB, but did not differ from blood group O. Finally, to examine whether ABO(H) blood group antigens contributed to VWF cleavage, 82 plasma samples were exposed to high shear stress using a cone-plate shear stress inducer. The difference in the VWF-DP/VWF:Ag ratio before and after high shear stress in blood group O was significantly greater than those in groups A and AB. CONCLUSION: These results indicate that blood group antigen A on VWF was more protective against ADAMTS13 cleavage than antigens B and H.

Haptoglobin degradation product as a novel serum biomarker for hematopoietic stem cell transplant-associated thrombotic microangiopathy.

BACKGROUND: Hematopoietic stem cell transplant (HSCT)-associated thrombotic microangiopathy (TA-TMA) is a well-known complication of HSCT and carries high risk of morbidity and mortality. A lack of consistent non-invasive diagnostic criteria can delay diagnosis and lead to irreversible organ damage. METHODS: Serum samples of 100 patients that underwent HSCT at Cincinnati Children's Hospital were serially collected. Unbiased proteomic profiling by SELDI-TOF-MS was performed on serum from TA-TMA patients at baseline (pre-HSCT), 2 weeks before TMA diagnosis (pre-TMA), and at clinical TMA diagnosis. Two proteins with mass to charge ratios of 12-13 kDa were consistently elevated at the 2 week pre-TMA time point by SELDI-TOF, compared to control samples. Potential peptides were isolated and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) on the Linear Trap Quadropole (LTQ). A MASCOT search identified haptoglobin fragments in the 12-17-kDa range. Western blot was performed to validate haptoglobin fragments as a potential biomarker. RESULTS: Western blot of TA-TMA patients showed haptoglobin fragments at 12, 14, and 17 kDa that varied between baseline, pre-TMA, and TMA time points for each patient. By densitometric analysis, the 17-kDa fragment in the pre-TMA samples differed significantly from TMA diagnosis (p < 0.0001). There was no significant difference in the concentrations of the 12-kDa and 14-kDa fragments. CONCLUSION: The 17-kDa haptoglobin degradation product may represent a novel early serum biomarker for TA-TMA that could potentially allow for earlier diagnosis and intervention.

Inhibition of the metabolic degradation of filtered albumin is a major determinant of albuminuria.

Inhibition of the degradation of filtered albumin has been proposed as a widespread, benign form of albuminuria. There have however been recent reports that radiolabeled albumin fragments in urine are not exclusively generated by the kidney and that in albuminuric states albumin fragment excretion is not inhibited. In order to resolve this controversy we have examined the fate of various radiolabeled low molecular weight protein degradation products (LMWDPs) introduced into the circulation in rats. The influence of puromycin aminonucleoside nephrosis on the processing and excretion of LMWDPs is also examined. The status and destinies of radiolabeled LMWDPs in the circulation are complex. A major finding is that LMWDPs are rapidly eliminated from the circulation (>97% in 2 h) but only small quantities (<4%) are excreted in urine. Small (<4%) but significant amounts of LMWDPs may have prolonged elimination (>24 h) due to binding to high molecular weight components in the circulation. If LMWDPs of albumin seen in the urine are produced by extra renal degradation it would require the degradation to far exceed the known catabolic rate of albumin. Alternatively, if an estimate of the role of extra renal degradation is made from the limit of detection of LMWDPs in plasma, then extra renal degradation would only contribute <1% of the total excretion of LMWDPs of albumin. We confirm that the degradation process for albumin is specifically associated with filtered albumin and this is inhibited in albuminuric states. This inhibition is also the primary determinant of the massive change in intact albuminuria in nephrotic states.

[The content of substances of low and medium molecular mass in biologic liquids in patients with erysipelas].

The endogenic intoxication is a metabolic response to any aggressive factor. The concentration of substances of low and medium molecular mass biologic liquids of organism w and medium molecular mass is a common indicator of intoxication syndrome. The study analyzed the role of uptake of substances of low and medium molecular mass in biologic liquids of organism in pathogenesis of erysipelas depending on period, form and ration of disease. The sampling included 76 patients with erysipelas aged from 27 to 62 years being in infection hospital for treatment. The concentration of substances of low and medium molecular mass was detected using M. Ya. Malakhova technique (1996). It is established that under erysipelas in organism occurs uptake of toxic substances in blood and gradual increase of concentration of substances of low and medium molecular mass in blood plasma and erythrocytes paralleled by corresponding changes of their concentration in urine. The altitude of increase of concentration level of substances of low and medium molecular mass and their reapportion between biologic mediums of organisms depends on period, form, ratio of course and degree of severity of pathologic process.