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Onze planeet komt aan; elke dag gemiddeld zo’n 0,16 gram per vierkante kilometer. Voor Nederland is dat al snel 7 kilo. Wereldwijd gaan de voorzichtigste schattingen uit van 30.000 ton per jaar. Die gewichtstoename komt vooral door microscopische stofdeeltjes uit de ruimte. Waar blijft al dat stof en wat kunnen we ermee?

Plasmodium falciparum infection results in adhesion of infected erythrocytes to blood vessel endothelium, and acute endothelial cell activation, together with sequestration of platelets and leucocytes. We have previously shown that patients with severe infection or fulminant cerebral malaria have significantly increased circulatory levels of the adhesive glycoprotein von Willebrand factor (VWF) and its propeptide, both of which are indices of endothelial cell activation. In this prospective study of patients from Ghana with severe (n = 20) and cerebral (n = 13) P. falciparum malaria, we demonstrate that increased plasma VWF antigen (VWF:Ag) level is associated with disproportionately increased VWF function. VWF collagen binding (VWF:CB) was significantly increased in patients with cerebral malaria and severe malaria (medians 7.6 and 7.0 lU/ml versus 1.9 IU/ml;p

De Canon van het Landschap vertelt over de ontstaansgeschiedenis van de Nederlandse landschappen (brede rivieren, meren, waterrijke veenpolders, blinkende duinen, stuwwallen, uitgestrekte wadden enz.).

Een landschapsatlas als deze is nog niet eerder verschenen. Hij beschrijft de geschiedenis van het landschap van Walcheren, vanaf het ontstaan tot nu toe. Die beschrijving is het boeiende verhaal van de natuur die eerst vormgaf aan het landschap en van de bewoners van dit gebied die geleidelijk aan de ontwikkeling hebben bepaald. Inspirerende sporen van tijd, zo luidt de ondertitel. Daarom gaat het namelijk in deze atlas: hoe ziet de toekomst van Walcheren eruit, wanneer rekening gehouden wordt met de sporen van tijd, die zich manifesteren in het aardkundig, archeologisch en cultuurhistorisch erfgoed. De landschapsgeschiedenis beslaat het grootste deel van de atlas. Deze is geïllustreerd met veel uniek kaartmateriaal, met afbeeldingen van prenten en schilderijen die voor een deel nooit eerder werden gepubliceerd, en met veel historische en nieuwe fotografische beelden.

Adherence of neutrophils and monocytes to endothelium is an important event in the sequence of leukocyte responses to inflammatory disease. Double-color flow microfluorimetry analysis was used to determine neutrophil and monocyte adherence to suspended endothelial cells under stirred conditions. The static adherence to endothelial cell monolayers was simultaneously determined. In both assays, neutrophils behaved in a similar way. Basal adherence of neutrophils was very low. Activation by PMA or by the chemoattractants platelet-activating factor and FMLP induced rapid binding, primarily mediated by CR3. Nonactivated neutrophils showed CD18-dependent (lymphocyte function-associated Ag-1 and CR3) and CD18-independent adherence to endothelial cells when the endothelial cells were prestimulated with rIL-1 beta. In contrast to neutrophils, nonactivated monocytes adhered avidly to resting endothelial cells. This adherence was partly CD18 dependent and partly CD18 independent. Whereas monocyte adherence under stirred conditions strongly increased upon activation by PMA, a significant decrease in adherence was found under static conditions, which was prevented by cytochalasin B. This decrease was limited to a distinct CD18-independent binding mechanism, and absent under stirred conditions. We conclude that monocytes adhere with (at least) three binding mechanisms to endothelial cells, a CD18-dependent and two CD18-independent mechanisms.

Introduction: The availability of image derived input functions (IDIF) obviates the need for arterial blood sampling and thereby facilitates clinical use of quantitative PET studies. The aim of this study was to develop a method for deriving IDIFs using reconstruction-based partial volume correction (PVC) [1]. Methods: PET and arterial blood data from nine dynamic [11C]flumazenil scans, acquired using an ECAT EXACT HR+ scanner and an on-line blood sampler, were used to develop and evaluate the method. Scans were reconstructed using both standard (no PVC) ordered subset expectation maximization (OSEM, 2 iterations, 16 subsets) and a PVC-OSEM algorithm, which corrects for the spatial resolution of the scanner. Number of iterations and width of PVC kernel were varied. The following regions of interest (ROIs) Methods: were evaluated for defining cerebral arteries: (a) pixel value threshold, (b) variable number of 'hottest' pixels per plane, (c) region growing, (d) cluster analysis, and (e) MR-based ROI. ROIs were defined on a pseudo blood volume image, generated by summation of early frames (

Phaeochromocytomas are rare neuroendocrine tumours that produce symptoms through excess release of catecholamines. Treatment of choice is elective, complete surgical removal after pretreatment with alpha-adrenergic blocking drugs, to prevent dangerous haemodynamic fluctuations. In rare cases a 'catecholamine crisis' develops presenting with pulmonary oedema and circulatory shock. We report such a case of a patient with familial extra-adrenal phaeochromocytoma who successfully underwent emergency surgery. Pathophysiological mechanisms are discussed. Although pretreatment with alpha-adrenergic blocking drugs seems advisable in terms of morbidity and mortality, the concept is based on theory rather than clinical evidence. Surgical management of a catecholamine crisis is associated with high mortality rates. However, proof of better outcome by avoidance or discontinuation of emergency surgery is not available. Based on literature and on this case, we conclude that emergency surgery in phaeochromocytoma does not have to be structurally avoided and may be considered under life-threatening circumstances

A 78-year-old female had chest pain, radiating to the back, caused by a thoracic aneurysm of the aorta. A vascular prosthesis was sutured into place through a left-sided thoracotomy. Six days after the operation she developed chylothorax on the right side. Following 14 days of conservative management, chyle leakage persisted at a rate of 1500 ml per 24 hours. By thoracoscopy the thoracic duct was dissected and clipped, which stopped the chyle leakage. The patient recovered moderately well. Conservative measures, such as adjusted nutrition, are successful in 50% of patients. Clipping of the thoracic duct by thoracoscopy is a definitive and minimally invasive procedure to treat persistent chyle leakage.

Patients with cross-reacting material (CRM)-reduced haemophilia A exhibit reduced levels of factor VIII antigen. In this study, we determined the molecular basis of the genetic defect in the factor VIII gene induced by either the Arg593-->Cys or the Asn618-->Ser missense mutation, identified in two CRM-reduced haemophilia A patients. We introduced either the Arg593-->Cys or the Asn618-->Ser mutation into a B-domain-deleted factor VIII cDNA and expressed the modified cDNAs in C127 cells. Reduced levels of factor VIII activity and factor VIII antigen in conditioned medium of transfected cells indicated that the secretion of both factor VIII variants was impaired. The ratio of factor VIII antigen present in cell extract to that in conditioned medium was 1.9 and 2.4 times higher for rFVIII-R593C and rFVIII-N618S, respectively, than for rFVIII. Metabolic labelling and immunoprecipitation of transfected cells revealed that rFVIII-R593C and rFVIII-N618S persisted somewhat longer inside the cell than factor rFVIII. Intracellular accumulation and subsequent degradation of factor VIII-R593C and factor VIII-N618S may explain the reduced levels of both factor VIII activity and antigen in plasma of mild haemophilia A patients with corresponding genetic defects

Before de novo synthesized von Willebrand factor (vWF) leaves the endothelial cell, it undergoes endoproteolytic cleavage of its propeptide (vW antigen II). The processed vWF and propeptide are either released constitutively or, following activation of the endothelium, released through the regulated pathway. In a recent study (Borchiellini et al, Blood 88:2951, 1996), we showed that the half-life of mature vWF and of its propeptide differ fourfold to fivefold. We postulated that the molar ratio of the propeptide to mature vWF could serve as a tool to assess the extent of endothelial cell activation under physiologic and clinical conditions. To test this hypothesis, we measured mature vWF and propeptide in patients with documented acute and chronic vascular disease, including patients with thrombotic thrombocytopenic purpura (TTP), acute septicemia, and diabetes mellitus. These data were compared with experimental conditions in healthy subjects in which perturbation of the endothelium was simulated by physical exercise or by administration of 1-deamino-8-D-arginine vasopressin (DDAVP) or endotoxin. In all individuals of the latter study group, both vWF and propeptide levels were elevated during the acute phase of the experimentally induced vascular perturbation; at later time points after stimulation, only vWF levels remained elevated. In patients with sepsis and TTP, both vWF and propeptide were elevated several-fold. Thus, this pattern can readily be explained in terms of acute perturbation of the endothelium. In contrast, in patients with diabetes mellitus propeptide levels were only slightly elevated, whereas vWF levels were elevated twofold to threefold. This pattern is a typical feature of chronic, low-grade activation of the endothelium. These observations support our hypothesis that measurement of both propeptide and vWF levels allows to discriminate between chronic and acute phases of endothelial cell activation in vivo. Measurement of only vWF is less indicative in this respect

Small GTP-binding proteins of the Ras superfamily control an extensive number of intracellular events by alternating between GDP- and GTP-bound conformation. The presence of members of this protein family was examined in human umbilical vein endothelial cells employing RT-PCR. Sequence analysis of 215 cDNA clones revealed the presence of a total of 28 different partial cDNAs encoding small GTP-binding proteins. Two sequences corresponded to novel isoforms of Rab2 and Rab9. In addition, human analogues of Rab4b, Rab7, Rab9, Rab14 and Rab15 were identified. Besides Rab proteins, members of other subfamilies were detected as well. As a first step towards elucidation of the function of the different small GTP-binding proteins identified we have isolated full length cDNA corresponding to Rab30 from a human endothelial cell cDNA library. In order to assess the subcellular localization of Rab30, we expressed epitope-tagged Rab30 cDNA in monkey kidney COS-1 cells. Immunoelectron-microscopy of transfected COS-1 cells indicated that Rab30 is associated with Golgi stacks

The development of inhibitory antibodies to factor VIII in patients affected by a mild form of hemophilia A (factor VIII > 0.05 IU/mL) is considered a rare event. In this study, we evaluated the relationship between genotype and anti-factor VIII antibody formation in a patient with mild hemophilia A. Mutation analysis showed that a missense mutation in the factor VIII gene leading to replacement of Arg593 by Cys in the A2 domain of factor VIII was associated with hemophilia A in this patient. The anti-factor VIII antibodies present in the patient's plasma were characterized using metabolically labeled factor VIII fragments expressed in insect cells. The anti-factor VIII antibodies, composed of subclasses IgG2 and IgG4, reacted with both the fragment corresponding to the factor VIII heavy chain and the A2 domain. The Arg593 --> Cys substitution was introduced into the cDNA encoding the A2 domain of factor VIII and the resulting construct was expressed in insect cells. Strikingly, the metabolically labeled A2 domain carrying the Arg593 --> Cys mutation was not recognized by the anti-factor VIII antibodies present in the plasma of the patient. These data indicate that the anti-factor VIII antibodies are exclusively directed against exogenous factor VIII. This strongly suggests that the Arg593 --> Cys substitution results in recognition of wild-type factor VIII as nonself and is thereby related to the formation of anti-factor VIII antibodies after factor VIII replacement therapy in this particular patient

Tumor necrosis factor (TNF) is an important mediator of the host responses to systemic infection. To investigate the effect of TNF on the release of von Willebrand factor (vWF) into the circulation, we performed a controlled study in six healthy men, sequentially measuring the plasma concentrations of vWF antigen after a bolus intravenous injection of recombinant human TNF (50 micrograms/m2). TNF induced a marked increase in vWF antigen plasma levels, becoming significant after 45 min and peaking after 4 h (percentage increase from base line: 351 +/- 46; p less than 0.0001, TNF versus saline). The multimeric organization of circulating vWF was not affected by TNF. We conclude that TNF may be an early mediator of increased vWF secretion in systemic infection