Effect of transfusion therapy on cerebral vasculopathy in children with sickle-cell anemia

This retrospective study assessed the long-term effect of transfusional exchange therapy on MRA/MRI abnormalities in 24 homozygous sickle-cell anemia (HbSS) children presenting with abnormal brain MRA. The median time elapsed from baseline to last available MRA was 29 months. Follow-up MRAs showed improvement, stabilization or worsening of cerebrovascular lesions in 11, 6 and 7 patients respectively. Complete normalization of MRA was observed in 6 patients within a mean time of 1.4 years, but stenosis recurred at the same location in the 4 patients in whom transfusion therapy was discontinued. Baseline severe stenosis/occlusion of large cerebral arteries and occurrence of moyamoya syndrome were significantly associated with an absence of improvement of the cerebral vasculopathy. These data emphasize the heterogeneity of the course of cerebrovasculopathy in SS children receiving chronic transfusion. Further studies are needed to determine whether different therapeutic approaches have to be considered according to these different evolutive patterns in SS children.     

A risk score for the management of pregnant women with increased risk of venous thromboembolism: a multicentre prospective study

Patients with thrombophilia and/or a history of venous thromboembolism (VTE) exhibit a high risk of thrombosis during pregnancy. The present multicentre study prospectively assessed a prophylaxis strategy, based on a risk score, in pregnancies with increased risk of VTE. Among 286 patients included in the study, 183 had a personal history of VTE (63·98%) and 191 patients (66·8%) had a thrombophilia marker. Eighty nine (46·6%) thrombophilic women had a personal history of VTE. Patients were assigned to one of three prophylaxis strategies according to the risk scoring system. In postpartum, all patients received low molecular weight heparin (LMWH) prophylaxis for at least 6 weeks. In antepartum, LMWH prophylaxis was prescribed to 61·8% of patients with high risk of VTE. Among them, 37·7% were treated in the third trimester only and 24·1% were treated throughout pregnancy. In this cohort, one antepartum-related VTE (0·35%) and two postpartum-related VTE (0·7%) occurred. No case of pulmonary embolism was observed during the study period. The rate of serious bleeding was 0·35%. There was no evidence of heparin-induced thrombocytopenia or osteoporosis. The use of a risk score may provide a rational decision process to implement safe and effective antepartum thromboprophylaxis in pregnant women at high risk of VTE.     

Omalizumab therapy in atopic dermatitis: depletion of IgE does not improve the clinical course – a randomized,placebo‐controlled and double blind pilot study

Background: Our understanding of the pathogenic role of IgE in atopic dermatitis is incomplete. We asked whether blocking free IgE would alter the course of the disease. Patients and Methods: We administered either omalizumab, a humanized monoclonal mouse antibody against IgE, or placebo subcutaneously for 16 weeks to 20 atopic dermatitis patients and measured immunological and clinical disease parameters. Results: Omalizumab (I) reduced free serum IgE, (II) lowered surface IgE and Fc?RI expression on different peripheral blood mononuclear cells, (III) reduced the saturation of Fc?RI with IgE, (IV) increased the number of free Fc?RI and (V) lowered the number of IgE+, but not of Fc?RI+ cells in skin. The in vivo relevance of these results is evidenced by the increase in the threshold allergen concentration required to give a type I hypersensitivity reaction in the titrated skin test. While not significantly altering the clinical disease parameters, omalizumab treatment led to an improvement of the atopy patch test results in single patients, i.e. an eczematous reaction upon epicutaneous allergen challenge. Conclusions: The interference with immediate and delayed type skin tests may imply that a therapeutic benefit of omalizumab treatment, if present at all, would be seen in patients with acute rather than chronic forms of the disease.     

VKORC1 −1639G>A and CYP2C9*3 are the major genetic predictors of phenprocoumon dose requirement

Purpose

Phenprocoumon, similar to other coumarin-derived anticoagulants, is associated with a large variation in the individual dose requirement to achieve stable anticoagulation. Polymorphisms in the vitamin K epoxide reductase complex subunit 1 (VKORC1) and the liver enzyme cytochrome P450 2C9 (CYP2C9) effectively account for the variability in warfarin and acenocoumarol response but are less well-defined pharmacogenetic predictors in phenprocoumon therapy.

Methods

A retrospective study was performed on 185 outpatients attending anticoagulation clinics in Austria and Germany. These patients were genotyped for the VKORC1 ?1639G>A and 3730G>A polymorphisms as well as for the CYP2C9 *2 and *3 polymorphisms using a reverse hybridisation-based teststrip assay.

Results

The VKORC1 ?1639A allele, which was present at a frequency of 41.4% in the study cohort, significantly reduced the mean weekly phenprocoumon dose by 3 mg (19%) in the heterozygous and by 6.7 mg (43%) in the homozygous state compared to wild-type carriers (15.5?±?6.8 mg, p?<?0.0001). A stepwise multiple regression analysis revealed that VKORC1 ?1639G>A, age and CYP2C9*3 were the major independent determinants of phenprocoumon dose, accounting for 14.2, 9.1 and 4.7% of its variability, respectively (p?≤?0.0007). The CYP2C9*2 polymorphism had a marginal influence (1.4%) and failed to reach statistical significance (p?=?0.062). The VKORC1 3730G>A genotype had no additional predictive power for individual dose variability.

Conclusion

Similar to warfarin and acenocoumarol, the VKORC1 ?1639G>A polymorphism had the highest impact on the maintenance dose of phenprocoumon. The factor age was the second most important predictor and explained a greater percentage of the variability than CYP2C9 genotype.     

Expression of protease-activated receptors and tissue factor in human liver

Thrombin, acting via protease-activated receptors (PARs), and tissue factor (TF) are involved in inflammation, tissue repair and tumorigenesis. Hepatocellular carcinomas (HCCs) usually complicate chronic liver diseases characterised by inflammation and fibrosis. The aim of this study was to describe the expression of PARs and TF in normal liver, cirrhosis and HCCs. We performed an immunohistochemical detection of PAR-1, PAR-3, PAR-4 and human TF in human tissue samples from 19 subnormal livers, 33 cirrhosis and 30 HCCs. PAR-1 was found on endothelial cells of sinusoids and larger vessels. In cirrhosis, spindle-shaped cells within septa and T lymphocytes were PAR-1 positive. A few PAR-1-positive tumour cells were found in 10% of HCCs. PAR-4 expression was restricted to macrophages, B lymphocytes and nerves. PAR-3 expression was rare. Unexpectedly, TF was expressed in 95% of normal livers and in 94% of cirrhosis but only in 50% of HCCs (p<0.001). Staining was mostly hepatocellular. No association existed between TF labelling and clinicopathological characteristics of HCCs. In conclusion, the pattern of expression of PARs is compatible with its role in chronic liver disease by promoting inflammation via immune cells and neurogenic stimulation. However, our data do not support a role for PARs or TF in HCC progression.     

Multifunctional Coupling Agents: 3. Segmented Block Copolymers Based on Carboxy‐Terminated Poly(propylene oxide) and Amino‐Terminated Polyamide 12

Summary: Segmented block copolymers were synthesized in melt by conversion of carboxy‐terminated poly(propylene oxide) and amino‐terminated PA12 with a selectively reacting bifunctional coupling agent bearing one oxazoline and one oxazinone group. The reaction was performed either in one or two steps. In the latter, it could be shown that the sequence of mixing significantly influenced the course of reaction. The structure of the linking group formed during the reaction was verified by ¹H NMR spectroscopy using model compounds. DSC and TEM investigations evidenced that the block copolymers are phase separated. Domains in a size of several nanometers are found. Owing to the two phase structure, the block copolymers show ductile behavior with the tendency to elastomeric behavior. Tensile properties of the block copolymers increase with the content of PA12. Elongations at break were measured with values up to 500%.

TEM micrograph of block copolymer 6b .     

NMR Study of Hyperbranched Polyphenylenes from the AB2, (AB2 + AB) and (A2 + B3) Methods

Summary: The ¹H NMR and ¹³C NMR spectra of hyperbranched polyphenylenes synthesised from AB₂, (AB₂ + AB) and (A₂ + B₃) monomers (A: ethynyl group; B: cyclopentadienonyl group) were analysed with respect to the characteristic substructures of these polymers. The broad and overlapping NMR spectra were studied by a combination of 1D and 2D NMR techniques. Furthermore, appropriate model compounds were synthesised, and their ¹H and ¹³C NMR spectra were fully assigned. The signal assignments achieved allow to substantiate the different hyperbranched polyphenylene structures. Steric hindrance in densely packed di‐ and trihexaarylphenyl substituted units of the (A₂ + B₃) polyphenylenes results in the decrease of the rotation frequency of phenyl rings in these structures to such an extent that the motion is slow on the ¹H NMR time scale. This can be proved both by EXSY and variable‐temperature experiments. Steric constraints were also deduced for the AB₂ polyphenylenes from signal line shape.

Selected spectra from a VT ¹H NMR experiment on polymer 7b (solvent: C₂D₂Cl₄; *–¹³C satellites of the solvent; signal at 7.3 ppm due to traces of CHCl₃).     

The truncated prelamin A in Hutchinson-Gilford progeria syndrome alters segregation of A-type and B-type lamin homopolymers

Hutchinson-Gilford progeria syndrome (HGPS) is a dominant autosomal premature aging syndrome caused by the expression of a truncated prelamin A designated progerin (Pgn). A-type and B-type lamins are intermediate filament proteins that polymerize to form the nuclear lamina network apposed to the inner nuclear membrane of vertebrate somatic cells. It is not known if in vivo both type of lamins assemble independently or co-assemble. The blebbing and disorganization of the nuclear envelope and adjacent heterochromatin in cells from patients with HGPS is a hallmark of the disease, and the ex vivo reversal of this phenotype is considered important for the development of therapeutic strategies. Here, we investigated the alterations in the lamina structure that may underlie the disorganization caused in nuclei by Pgn expression. We studied the polymerization of enhanced green fluorescent protein- and red fluorescent protein-tagged wild-type and mutated lamins in the nuclear envelope of living cells by measuring fluorescence resonance energy transfer (FRET) that occurs between the two fluorophores when tagged lamins interact. Using time domain fluorescence lifetime imaging microscopy that allows a quantitative analysis of FRET signals, we show that wild-type lamins A and B1 polymerize in distinct homopolymers that further interact in the lamina. In contrast, expressed Pgn co-assembles with lamin B1 and lamin A to form a mixed heteropolymer in which A-type and B-type lamin segregation is lost. We propose that such structural lamina alterations may be part of the primary mechanisms leading to HGPS, possibly by impairing functions specific for each lamin type such as nuclear membrane biogenesis, signal transduction, nuclear compartmentalization and gene regulation.