Enhanced thrombin generation in plasma of severe thrombocytopenic patients due to rFVIIa

RFVIIa-enhanced thrombin generation has been shown to be dependent on platelets. In previous work we have shown that addition of monocytes and rFVIIa to microparticle free plasma causes a distinct thrombin generation. The aim of our study has been to examine whether there is enough surface provided by microparticles in thrombocytopenic plasma to allow an effect of rFVIIa. Patients, methods: Thrombin generation was measured in platelet rich plasma (PRP) and microparticle free plasma (MFP) of thrombocytopenic haemato-oncological patients with and without addition of rVIIa by means of calibrated automated thrombography. Microparticles were analyzed in PRP by FACS flow cytometry. Results: Microparticle free plasma showed no thrombin generation with or without addition of rFVIIa. Addition of rFVIIa to PRP of thrombocytopenic patients led to a significant shortening of lag time and time to peak in thrombin generation, while ETP and peak remained unchanged. Conclusion: Our results show that even in plasma of severe thrombocytopenic patients enough surface may be provided by microparticles to allow an enhancement of thrombin generation by rFVIIa.

The tissue distribution of lipoprotein lipase determines where chylomicrons bind

To determine the role of LPL for binding of lipoproteins to the vascular endothelium, and for the distribution of lipids from lipoproteins, four lines of induced mutant mice were used. Rat chylomicrons labeled in vivo with [(14)C]oleic acid (primarily in TGs, providing a tracer for lipolysis) and [(3)H]retinol (primarily in ester form, providing a tracer for the core lipids) were injected. TG label was cleared more rapidly than core label. There were no differences between the mouse lines in the rate at which core label was cleared. Two minutes after injection, about 5% of the core label, and hence chylomicron particles, were in the heart of WT mice. In mice that expressed LPL only in skeletal muscle, and had much reduced levels of LPL in the heart, binding of chylomicrons was reduced to 1%, whereas in mice that expressed LPL only in the heart, the binding was increased to over 10%. The same patterns of distribution were evident at 20 min when most of the label had been cleared. Thus, the amount of LPL expressed in muscle and heart governed both the binding of chylomicron particles and the assimilation of chylomicron lipids in the tissue.

Enhanced thrombin generation in plasma of severe thrombocytopenic patients due to rFVIIa

RFVIIa-enhanced thrombin generation has been shown to be dependent on platelets. In previous work we have shown that addition of monocytes and rFVIIa to microparticle free plasma causes a distinct thrombin generation. The aim of our study has been to examine whether there is enough surface provided by microparticles in thrombocytopenic plasma to allow an effect of rFVIIa.

PATIENTS, METHODS

Thrombin generation was measured in platelet rich plasma (PRP) and microparticle free plasma (MFP) of thrombocytopenic haemato-oncological patients with and without addition of rVIIa by means of calibrated automated thrombography. Microparticles were analyzed in PRP by FACS flow cytometry.

RESULTS

Microparticle free plasma showed no thrombin generation with or without addition of rFVIIa. Addition of rFVIIa to PRP of thrombocytopenic patients led to a significant shortening of lag time and time to peak in thrombin generation, while ETP and peak remained unchanged.

CONCLUSION

Our results show that even in plasma of severe thrombocytopenic patients enough surface may be provided by microparticles to allow an enhancement of thrombin generation by rFVIIa.

Thrombin generation before and after multicomponent blood collection

The development of apheresis technology has increased efficiency in donor blood use by collecting specific blood components in several combinations. The question of donor safety raised by the contact of donor blood with foreign, only in part biocompatible surfaces remains. The aim of this study was to estimate the effect of multicomponent blood collection on thrombin generation performing an overall function test of coagulation.

DONORS, METHODS

26 blood donors were included. Per apheresis two units of platelets and one unit of RBCs were collected by two cell separators (Amicus and Trima Accel). Each donor underwent the procedure on both apheresis systems. Samples were collected before, immediately after, and 48 hours after apheresis. Thrombin generation was measured by means of calibrated automated thrombography (CAT).

RESULTS

CAT-data changed only slightly and no significant changes were seen before, immediately after, and 48 hours after apheresis. The parameters did not differ significantly between the two different apheresis devices.

CONCLUSION

No change in parameters of continuous thrombin generation occurred, suggesting that apheresis did not lead to severe alterations in the haemostatic system.

Thrombin generation before and after multicomponent blood collection

IThe development of apheresis technology has increased efficiency in donor blood use by collecting specific blood components in several combinations. The question of donor safety raised by the contact of donor blood with foreign, only in part biocompatible surfaces remains. The aim of this study was to estimate the effect of multicomponent blood collection on thrombin generation performing an overall function test of coagulation. Donors, methods: 26 blood donors were included. Per apheresis two units of platelets and one unit of RBCs were collected by two cell separators (Amicus® and Trima Accel®). Each donor underwent the procedure on both apheresis systems. Samples were collected before, immediately after, and 48 hours after apheresis. Thrombin generation was measured by means of calibrated automated thrombography (CAT). Results: CATdata changed only slightly and no significant changes were seen before, immediately after, and 48 hours after apheresis. The parameters did not differ significantly between the two different apheresis devices. Conclusion: No change in parameters of continuous thrombin generation occurred, suggesting that apheresis did not lead to severe alterations in the haemostatic system.

The role of lipoprotein lipase in adipose tissue development and metabolism

Lipoprotein lipase (LPL) is essential for the hydrolysis and distribution of triglyceride-rich lipoprotein-associated fatty acids among extrahepatic tissues. Additionally, the enzyme facilitates several non-lipolysis associated functions including the cellular uptake of whole lipoprotein particles and lipophilic vitamins. The tissue-specific variations of LPL expression have been implicated in the pathogenesis of various lipid disorders, obesity and atherosclerosis. Transgenic technology provided the means to study the physiological response to the overexpression or absence of the enzyme in adipose tissue, muscle and macrophages. The effects of varying LPL expression in adipose tissue and muscle are summarized in this article.

cDNA cloning and analysis of tissue-specific expression of mouse peroxisomal straight-chain acyl-CoA oxidase

Straight-chain acyl-CoA oxidase is the first and rate limiting enzyme in the peroxisomal beta-oxidation pathway catalysing the desaturation of acyl-CoAs to 2-trans-enoyl-CoAs, thereby producing H2O2. To study peroxisomal beta-oxidation we cloned and characterized the cDNA of mouse peroxisomal acyl-CoA oxidase. It consists of 3778 bp, including a 1983-bp ORF encoding a polypeptide of 661 amino-acid residues. Like the rat and human homologue the C-terminus contains an SKL motif, an import signal present in several peroxisomal matrix proteins. Sequence analysis revealed high amino-acid homology with rat (96%) and human (87%) acyl-CoA oxidase in addition to minor homology ( approximately 40%) with other related proteins, such as rabbit trihydroxy-cholestanoyl-CoA oxidase, human branched chain acyl-CoA oxidase and rat trihydroxycoprostanoyl-CoA oxidase. Acyl-CoA oxidase mRNA and protein expression were most abundant in liver followed by kidney, brain and adipose tissue. During mouse brain development acyl-CoA oxidase mRNA expression was highest during the suckling period indicating that peroxisomal beta-oxidation is most critical during this developmental stage. Comparing tissue mRNA levels of peroxisome proliferator-activated receptor alpha and acyl-CoA oxidase, we noticed a constant relationship in all tissues investigated, except heart and adipose tissue in which much more, and respectively, much less, peroxisome proliferator-activated receptor alpha mRNA in proportion to acyl-CoA oxidase mRNA was found. Our data show that acyl-CoA oxidase is an evolutionary highly conserved enzyme with a distinct pattern of expression and indicate an important role in lipid metabolism.

cDNA cloning of the human peroxisomal enoyl-CoA hydratase: 3-hydroxyacyl-CoA dehydrogenase bifunctional enzyme and localization to chromosome 3q26.3-3q28: a free left Alu Arm is inserted in the 3' noncoding region

Enoyl-CoA hydratase:3-hydroxyacyl-CoA dehydrogenase bifunctional enzyme is one of the four enzymes of the peroxisomal beta-oxidation pathway. Here, we report the full-length human cDNA sequence and the localization of the corresponding gene on chromosome 3q26.3-3q28. The cDNA sequence spans 3779 nucleotides with an open reading frame of 2169 nucleotides. The tripeptide SKL at the carboxy terminus, known to serve as a peroxisomal targeting signal, is present. DNA sequence comparison of the coding region showed an 80% homology between human and rat bifunctional enzyme cDNA. The 3' noncoding sequence contains 117 nucleotides homologous to an Alu repeat. Based on sequence comparison, we propose that these nucleotides are a free left Alu arm with 86% homology to the Alu-J family. RNA analysis shows one band with highest intensity in liver and kidney. This cDNA will allow in-depth studies of molecular defects in patients with defective peroxisomal bifunctional enzyme. Moreover, it will also provide a means for studying the regulation of peroxisomal beta-oxidation in humans.

Pathologic features of placentas from singleton pregnancies obtained by in vitro fertilization and embryo transfer

Fifty placentas were collected at term from singleton pregnancies resulting from in vitro fertilization (IVF) and intrauterine embryo transfer. Their pathologic features were compared with those of a control group composed of 50 placentas obtained from spontaneous singleton pregnancies. The mean maternal age, mean gestational age, mean fetal weight, sex ratio, and rate of pregnancy complications did not differ. There was also no significant difference between the groups in the mean placental weight and in the incidence of placental pathologic lesions, including extended infarcts, massive perivillous fibrin depositions, chorioangiomas, and placental inflammatory lesions. The incidence of abnormal placental shapes was significantly (P less than .05) greater in the IVF group (22%) compared with the control group (6%). A significant (P less than .025) difference was observed between the groups in the distribution of umbilical cord insertions. The mean distance between the cord insertion and the closest placental margin was significantly (P less than .005) shorter in the group conceived by IVF (3.23 +/- 1.91 cm) than in the control group (4.54 +/- 2.42 cm). A relationship between these placental morphologic features and the superficial implantation and/or inadequate orientation of the blastocyst after IVF and intrauterine embryo transfer is proposed.

Hepatic telangiectasia and cirrhosis

In a woman with hereditary hemorrhagic telangiectasia (HHT) (Osler-Weber-Rendu disease) who died of fulminant hepatitis B, autopsy revealed cirrhosis of the liver and diffuse hepatic telangiectasia. Her daughter and grandson also suffered from the hepatic involvement of HHT. Sufficient laboratory investigations were available to exclude known causes of cirrhosis. We review the relationship between Osler-Weber-Rendu disease and liver cirrhosis or fibrosis.