Elevated tissue factor circulating levels in children with hemolytic uremic syndrome caused by verotoxin-producing E. coli.

BACKGROUND: Microvascular thrombosis in the kidney plays an important role in the pathogenesis of hemolytic uremic syndrome (HUS). Tissue factor (TF), present on the vascular surface of endothelial cells, binds factor VIIa. The complex initiates the coagulating cascade by activating factors X and IX. PATIENTS AND METHODS: In cases of HUS associated with verotoxin-producing E. coli (VTEC) infection, VTEC gastroenteritis without HUS and normal controls, we measured plasma concentrations of TF and tissue factor pathway inhibitor (TFPI) to evaluate their clinical significance. In children with non-HUS chronic renal failure (CRF), the TF levels were also measured as another control group. RESULTS: In the acute phase of HUS, plasma levels of TF and TFPI were significantly elevated, then returned to normal range in the recovery phase. The TF levels were closely correlated with the thrombin antithrombin-III complex, a marker of thrombin activity in circulating blood, and with creatinine clearance (Ccr). Furthermore, a positive correlation was noted between plasma TF levels and plasma soluble thrombomodulin (sTM) levels, which is a marker of endothelial cell injury. The influence of decreased excretion from damaged kidneys should be considered since a definite lot correlation was observed between plasma TF levels and Ccr in children with non-HUS CRF. CONCLUSION: From these findings, we concluded that elevated TF circulating levels may also play an important role in blood-clotting activation observed in VTEC-HUS patients, and may also be a useful marker for renal damage.

Abnormal proteolytic processing of von Willebrand factor Arg611 Cys and Arg611His.

The structural and functional properties of plasma and platelet vWF were studied in 8 patients (5 unrelated families) with vWD demonstrating a mutation at position 611 (R611C or R611H). Following reduction, electrophoresis and immunoblotting with a polyclonal anti-reduced vWF antibody, abnormal proteolysis of vWF was demonstrated in plasma and to a lesser extent in platelets from all patients, leading to the formation of a unique 209 kDa fragment undetectable in control as well as in type 2A, 2B or 2N vWF. Immunoblotting with MoAbs to reduced vWF showed that the C-terminal end of the 209 kDa fragment was located beyond residue 1744 of the subunit and that its N-terminus was between residues 523 and 1114. Multimeric analysis of patients vWF showed an abnormal pattern in both plasma and platelets, with a moderate decrease of the HMW multimers together with a significant increase of the lowest MW forms. The specific sensitivity of vWF R611C and vWF R611H to proteolysis was further evidenced using V-8 protease. In all patient's samples the enzyme produced a unique monomeric 80 kDa fragment, absent in V-8 digested normal vWF, which overlapped the N-terminal part of the subunit. The functional analysis of vWF showed a markedly decreased affinity of mutated plasma vWF for platelet GPIb in the presence of ristocetin. Infusion of DDAVP in two of these patients did not lead to significant platelet count change. It induced a limited increase of the HMW multimers in plasma together with a poor correction of the vWF binding to platelet GPIb. In conclusion, our data demonstrate that in addition to a normal proteolysis, vWF mutated at position 611 undergoes a specific cleavage in plasma and platelets. In contrast to the increased proteolysis observed in type 2A and 2B patients' plasma, this additional cleavage produced a unique 209 kDa species but maintained a HMW multimer-like structure of vWF R611C and R611H.

[Pancreatic function after pancreatoduodenectomy--correlation between the volume ratio of parenchyma and the number of Langerhans' islets].

Correlation between the volume ratio of the pancreatic parenchyma and the volume of hydroxyproline in the pancreatic tissue was studied in 9 mongrel dogs with pancreatic-duct ligation. The volume ratio of the pancreatic parenchyma and the number of Langerhans' islets were determined in 11 normal pancreas. And the relationship between the volume ratio of the pancreatic parenchyma in the 37 resected pancreas by pancreatoduodenectomy (PD) and the functions in the remaining pancreas after PD, was examined. The following results were obtained: The method to determine the volume ratio of the pancreatic parenchyma by using a Roller-planimeter proved to be a simple and convenient to find out the extent of pancreatic fibrosis. The volume ratio of the pancreatic parenchyma in normal pancreas was almost uniform over the whole pancreas. The number of Langerhans' islets in the tail of normal pancreas was about 1.5 times as many as that at the resection line by the scheduled PD. The volume ratio of the pancreatic parenchyma and the number of Langerhans' islets after PD were about half that in normal pancreas. Positive correlation was noted between the volume ratio of the pancreatic parenchyma and the post-operative pancreatic juice secreted at the time of PD. In the cases which the volume ratio of the pancreatic parenchyma was over 80%, the pancreatic juice secretion was over 200 ml/day. In many of the cases which the volume ratio of the pancreatic parenchyma was over 70%, the exocrine function in the remaining pancreas was good even three to four years after PD. Correlation was observed between the number of Langerhans' islets at PD and the post-operative glucose tolerance. In the cases which the number of Langerhans' islets was large, more favorable insulin secretory function was observed in the remaining pancreas.