Clinical Hemorheology and Microcirculation - Volume 32, issue 2

Authors: Franke, R.P.

Article Type: Other

Citation: Clinical Hemorheology and Microcirculation, vol. 32, no. 2, pp. 81-81, 2005

Authors: Gordz, S. | Mrowietz, C. | Pindur, G. | Park, J.W. | Jung, F.

Article Type: Research Article

Abstract: When patients with von Willebrand's disease were given a single injection of desmopressin (0.4 μg/kg body weight), there was a considerable increase in platelet reactivity (from 0.95±0.19 to 1.44±0.42; p=0.0033). On flow cytometry, increased glycoprotein Ib/IX expression in the platelets was found after the desmopressin injection; when phycoerythrin‐marked anti‐CD62 antibodies were used, the mean fluorescence rose from 428.9±56.6 to 440.7±51.4 (p=0.0056), and from 425.9±55.0 to 437.4±53.9 (p=0.0018) when phycoerythrin‐marked anti‐thrombospondin antibodies were used. Apart from the rise in the von Willebrand factor, this could explain the increased platelet reactivity. However, the surface expression of CD62, CD63 and thrombospondin on …platelets did not change following the desmopressin injection. Show more

Keywords: von Willebrand disease, platelet–membrane glycoprotein expression, desmopressin

Citation: Clinical Hemorheology and Microcirculation, vol. 32, no. 2, pp. 83-87, 2005

Authors: Mrowietz, C. | Franke, R.P. | Seyfert, U.T. | Park, J.W. | Jung, F.

Article Type: Research Article

Abstract: Acute and subacute stent thrombosis still represent an unsolved problem in connection with endovascular stents. For this reason coatings are tested now with the intention to reduce thrombogenicity of stainless steel surfaces. This comparative study examined whether a polymeric stent coating affected the haemocompatibility of a stainless steel stent. For compatibility testing, coated and non‐coated stents were implanted in a low‐grade thrombogenic closed‐loop system perfused with platelet rich plasma at shear rates far below the threshold value at which shear‐rate‐induced activation of thrombocytes occurs. After 21 circulations of the filling volume (exposure time: 6.2 min), the number of single circulating …platelets in the perfusion system with uncoated stainless steel stents decreased almost twice as much as was the case with polymer‐coated stents. This is thought to indicate that more thrombocytes had adhered to the uncoated stainless steel stent, or that the thrombocytes were clustered in circulating aggregates. Parallel to the platelet aggregation/adherence, a release reaction took place, as was evident from the TAT complexes indicating the generation of thrombin. In the case of the implantation of uncoated stainless steel stents, both the number of activated circulating thrombocytes and the level of platelet reactivity (number of thrombocytes circulating in the plasma as aggregates) were notably higher than in the system with polymer‐coated stents. At the same time it should be noted that the activation or aggregation is almost wholly attributable to the exogenic surface of the implanted stent, since activation due to the tube system or to shear rate can be excluded (as shown by measurements of the system without a stent). In addition to activation of the thrombocytes, a notable increase in the number of receptors per platelet (significant only in the system with the uncoated stent) took place. This supports both the adherence of the thrombocytes and their readiness to aggregate, since more receptors (docking places for ligands) are available. The better haemocompatibility of the polymer‐coated stents, as verified in the laboratory, was also evident under microscopic examination of the explanted stents following the perfusion tests. Show more

Keywords: Haemocompatibility, coronary stents, closed‐loop, polyphosphazenes

Citation: Clinical Hemorheology and Microcirculation, vol. 32, no. 2, pp. 89-103, 2005

Authors: Lendlein, A. | Kelch, S.

Article Type: Research Article

Abstract: Shape‐memory polymers are stimuli‐responsive materials. Upon exposure to an external stimulus, e.g. an increase in temperature, they have the capability of changing their shape. The shape‐memory effect results from the polymer's structure and morphology in combination with a certain processing and programming technology. Stimuli‐sensitive implant materials have a high potential for applications in minimally invasive surgery. A group of biodegradable implant materials with shape‐memory has been developed for applications in biomedicine. These implant materials are not a single polymer but polymer systems that allow the variation of different macroscopic properties over a wide range by only small changes in the …chemical structure. In this way, it is possible to implement a variety of different applications with tailor‐made polymers of the same family. Two different types of degradable shape‐memory polymer systems, covalently cross‐linked polymer networks and thermoplastic elastomers, are presented and examples are given for each case. Show more

Keywords: Biodegradable shape‐memory polymers, polymer systems, stimuli‐sensitive implant materials, smart suture

Citation: Clinical Hemorheology and Microcirculation, vol. 32, no. 2, pp. 105-116, 2005

Authors: Rickert, D. | Lendlein, A. | Kelch, S. | Moses, M.A. | Franke, R.‐P.

Article Type: Research Article

Abstract: Introduction: Using standard cell biological and biochemical experimental approaches we were able to test the ability of a particular polymer construct to support the adhesion, proliferation, and the cellular acitivity of pharyngeal cells. The delicate balance between Matrix Metalloproteinases (MMPs) and their endogenous inhibitors (Tissue Inhibitor of MMPs, TIMPs) have a decisive function in the remodeling of the extracellular matrix during cellular ingrowth. Novel polymeric biomaterials may be useful to develop new therapeutic options in head and neck surgery. Methods: Primary cell cultures of the pharynx of Sprague‐Dawley rats were seeded on the surface of a thermoplastic multi‐block copolymer and …on a polystyrene surface as control. Conditioned media of the primary cells was analyzed for MMPs and TIMPs. The MMP and TIMP expression was analysed by zymography and a radiometric enzyme assay. Results: No statistically significant differences in the levels of MMP‐1, MMP‐2, MMP‐9 and TIMPs were detected between cells grown on the novel polymer surface versus control. Conclusion: An appropriate understanding of the molecular machinery that regulates gene expression and cellular growth in tissue engineered contructs is the requirement for an optimal adaptation of biodegradable biomaterials to develop new therapeutic options in otolaryngology and head and neck surgery. Show more

Keywords: Primary cell cultures, pharynx, metalloproteinases, multi‐block copoolymer, head and neck surgery

Citation: Clinical Hemorheology and Microcirculation, vol. 32, no. 2, pp. 117-128, 2005

Authors: Groth, T. | Seifert, B. | Albrecht, W. | Malsch, G. | Gross, U. | Fey‐Lamprecht, F. | Michanetzis, G. | Missirlis, Y. | Engbers, G.

Article Type: Research Article

Abstract: Biomedical technology has opened up possibilities of treating the failure of internal organs like kidney and liver by artificial organ therapy. Most of these techniques are based on polymer membranes, which allow the removal of excess of water, salts and toxins from the circulation. However, haemodialysis for the replacement of kidney function results in an increased morbidity and mortality of patients after long‐term application. Conventional therapy, such as haemofiltration for the treatment of acute liver failure does not improve significantly the survival rate of patients. Biohybrid organ support as a combination of the artificial organ therapy with the functional activity …of immobilised cells seems to be a solution of the problem. Membranes applied in these devices have to face both tissue cells and blood. Organ cells in biohybrid organs have to make intimate contact with the surface of membrane but must also develop close cell–cell‐connections as a prerequisite for their survival and high functional activity. Blood to be detoxified will contact the other side of membrane and may not become activated by the synthetic material. New polymer membranes based on acrylonitrile were developed to address these requirements by tailoring the composition of copolymers and to be applied in a specific hollow fibre bioreactor with an outer fibre for blood contact, and an inner fibre for tissue contact or vice versa. Show more

Keywords: Bioartificial organs, haemocompatibility, kidney epithelial cells, polymer membranes

Citation: Clinical Hemorheology and Microcirculation, vol. 32, no. 2, pp. 129-143, 2005

Authors: Brandt, O.

Article Type: Research Article

Keywords: Rheometer, shear stress, hemocompatibility, histocompatibility, clotting/thrombus formation, biomaterial surfaces, platelets, rheometer system, GP‐VI antibody

Citation: Clinical Hemorheology and Microcirculation, vol. 32, no. 2, pp. 145-149, 2005

Authors: Beilin, Benzion | Mayburd, Eduard | Yardeni, Israel‐Zeev | Bessler, Hanna

Article Type: Research Article

Abstract: Laparoscopic surgery has become a widely used procedure with many advantages compared to conventional laparotomy. Although rare, this technique is not entirely absent from clinical hazards and particularly thromboembolic events. This complication is due to activation of the coagulation cascade, as well as factors that may cause alterations in blood rheology. Apart from high hematocrit, presence of abnormal proteins and elevated fibrinogen level, the type of anesthesia, temperature, and increased intra‐abdominal pressure following CO2 insufflation may affect blood viscosity. Therefore, the objective of the study was to compare rheological events in 17 patients undergoing laparoscopic surgery to those in …15 patients who underwent laparotomy. Both groups of patients did not show any complications during the early and late post‐operative period. The values of whole blood viscosity in patients undergoing laparoscopy did not differ from those in patients treated by laparotomy. A slight, although significant decrease in plasma viscosity and red blood cell aggregation was observed in patients who underwent laparotomy. The results suggest that the benefits of laparoscopic surgery in the present series were not affected by alterations in blood and plasma viscosity, as well as in red blood cell aggregation. Show more

Keywords: Viscosity, laparoscopy, laparotomy, cholecystectomy, hysterectomy

Citation: Clinical Hemorheology and Microcirculation, vol. 32, no. 2, pp. 151-157, 2005

Authors: van der Loo, Bernd | Kovacevic, Tamara | Krieger, Elisabeth | Banyai, Susanne | Banyai, Martin | Amann‐Vesti, Beatrice R. | Jagacic, Dorijan | Rousson, Valentin | Koppensteiner, Renate

Article Type: Research Article

Abstract: Rheological abnormalities are well known in patients with peripheral arterial occlusive disease (PAOD). We wanted to determine whether rheological variables are related to restenosis after femoropopliteal percutaneous transluminal angioplasty (PTA). In 114 patients (62 men; median age 70 years) undergoing femoropopliteal PTA for symptomatic peripheral arterial occlusive disease (PAOD) plasma viscosity, red cell aggregation, whole blood viscosity, hematocrit, fibrinogen, platelet count, leukocytes and C‐reactive protein were determined the day after the procedure and at 1, 3, and 12 months. The primary endpoint was restenosis >50% documented by duplexsonography up to 12 months. Cox proportional hazards analysis was used to assess …the risk of restenosis for postinterventional values of rheological variables. Forty‐eight patients (42%) developed restenosis at 12 months. Patients with restenosis had higher baseline plasma viscosity (PV) (medians, 1.71 vs. 1.65 millipascal seconds [mPa.s]; p=0.04) and lower platelet count (224 vs. 240×103 /μl; p=0.03) than patients without restenosis. The hazard ratio (HR; 95% CI) of incident restenosis was 9.2 (1.12–76; p=0.03) for PV and 0.99 (0.99–1.0; p=0.07) for PLT. When examining jointly both high PV and low platelet count (PLT), patients with PV > 1.66 mPa.s and PLT < 233×103 /μl (i.e. variables split at their respective median) had an increased risk of restenosis (log‐rank test p=0.01). Multivariate Cox proportional hazard analysis showed that plasma viscosity (p=0.02), low platelet count (p=0.01), lesion length (p=0.0037) and lack of hypertension (p=0.01) were associated with restenosis at 12 months. No associations were found between restenosis and the other rheological and inflammatory variables studied. Our data suggest that increased PV and low PLT contribute to restenosis after femoropopliteal PTA. Show more

Keywords: Balloon angioplasty, restenosis, platelets, plasma viscosity, blood rheology, femoropopliteal segment

Citation: Clinical Hemorheology and Microcirculation, vol. 32, no. 2, pp. 159-168, 2005

Article Type: Other

Citation: Clinical Hemorheology and Microcirculation, vol. 32, no. 2, pp. 169-170, 2005