Sterilization of heparinized Cuprophan hemodialysis membranes

The effects of sterilization of dry heparinized Cuprophan hemodialysis membranes by means of ethylene oxide (EtO) exposure, gamma irradiation, or steam on the anticoagulant activity and chemical characteristics of immobilized heparin and the permeability of the membrane were investigated. Sterilization did not result in a release of heparin or heparin fragments from heparinized Cuprophan. Sterilization of heparinized Cuprophan by means of EtO exposure and gamma irradiation induced a slight, insignificant decrease of the anticoagulant activity. In contrast, steam-sterilized heparinized Cuprophan showed a higher anticoagulant activity than unsterilized heparinized Cuprophan, which was most likely caused by cleavage of some of the covalent bonds between heparin and Cupropha. The effects of sterilization on the permeability of unmodified Cuprophan and heparinized Cuprophan were compared. The permeability of unmodified Cuprophan for vitamin B12 (Vit B12) and sulfobromophthalein (SBP) was reduced by 20–35% after EtO exposure and gamma irradiation and was reduced by 90–95% after steam sterilization. The water permeability of unmodified Cuprophan remained the same after EtO exposure and gamma irradiation but also dramatically reduced after steam sterilization. These reductions were ascribed to the collapse of pores of the membrane. The permeability of heparinized Cuprophan was not affected by EtO exposure and gamma irradiation but dramatically reduced after steam sterilization, although to a lesser extent than in the case of unmodified Cuprophan. Apparently, the presence of immobilized heparin (partially) prevented the collapse of pores during sterilization. Gamma irradiation was recommended as the preferred method of sterilization for heparinized Cuprophan.\u

Design of a new type of coating for the controlled release of heparin

Thrombus formation at the surface of blood contacting devices can be prevented by local release of heparin. Preferably, the release rate should be constant for prolonged periods of time. The minimum heparin release rate to achieve thromboresistance will be different for various applications and should therefore be adjustable. In this study a new type of heparin release system is presented which may be applied as a coating for blood contacting devices. The system is based on the covalent immobilization of heparin onto porous structures via hydrolysable bonds. This approach was evaluated by the immobilization of heparin onto a porous cellulosic substrate via ester bonds. Cuprophan was used as a model substrate and N,N¿-carbonyldiimidazole as a coupling agent. Heparinized Cuprophan incubated in phosphate buffered saline showed a release of heparin due to the hydrolysis of the ester bonds between heparin and Cuprophan. The release rate could be easily adjusted by varying the amount of coupling agent used during immobilization. Cuprophan with a rather stable heparin coating (release rate: 6.1 mU/cm2·h) and Cuprophan which shows a substantial release of heparin (release rate up to 23.0 mU/cm2·h) could be prepared. Except when the release was relatively high, release rates were constant for at least 1 week. Storage of the release system at ambient conditions up to 6 months or sterilization by means of steam, ethylene oxide exposure, or gamma irradiation did not affect the release properties. It was concluded that this concept for a heparin release system is highly promising to prepare thromboresistant surfaces for various blood contacting devices

An in vitro study of the adhesion of blood platelets onto vascular catheters. Part I

The adhesion of human blood platelets onto vascular catheters was studied using a specially designed perfusion chamber. Polyurethane catheters were exposed to citrated human blood for different periods (up to 20 min) and at different wall shear rates (190, 260, 330 sec-1). The rate of platelet adhesion was determined using 111In-labeled platelets, while the morphology of adhering platelets was investigated using scanning electron microscopy. A linear increase in platelet adhesion was found within the first 10 min of perfusion, after which a plateau value was reached. The number of adhering platelets did not vary significantly with the shear rates applied, which may indicate that within the range of shear rates studied, the adhesion of platelets onto the catheter surface is mainly determined by the rate of the reaction between the platelets and the material surface. Catheters coated with a conjugate of heparin and albumin showed a four- to five-fold reduction in platelet adhesion as compared to uncoated catheters. This reduction in platelet adhesion was not only due to the presence of albumin moieties at the surface but also to the presence of heparin residues in the adsorbed albumin-heparin conjugate

Elevated paleomagnetic dispersion at Saint Helena suggests long-lived anomalous behavior in the South Atlantic.

Earth's magnetic field is presently characterized by a large and growing anomaly in the South Atlantic Ocean. The question of whether this region of Earth's surface is preferentially subject to enhanced geomagnetic variability on geological timescales has major implications for core dynamics, core-mantle interaction, and the possibility of an imminent magnetic polarity reversal. Here we present paleomagnetic data from Saint Helena, a volcanic island ideally suited for testing the hypothesis that geomagnetic field behavior is anomalous in the South Atlantic on timescales of millions of years. Our results, supported by positive baked contact and reversal tests, produce a mean direction approximating that expected from a geocentric axial dipole for the interval 8 to 11 million years ago, but with very large associated directional dispersion. These findings indicate that, on geological timescales, geomagnetic secular variation is persistently enhanced in the vicinity of Saint Helena. This, in turn, supports the South Atlantic as a locus of unusual geomagnetic behavior arising from core-mantle interaction, while also appearing to reduce the likelihood that the present-day regional anomaly is a precursor to a global polarity reversal

Development and validation of a patient- tailored dose regime in myocardial perfusion imaging using conventional SPECT

Background\ud The decreasing image quality in heavier patients can be compensated by administration of a patient-specific dose in myocardial perfusion imaging (MPI) using a cadmium zinc telluride-based SPECT camera. Our aim was to determine if the same can be achieved when using a conventional SPECT camera.\ud \ud \ud Methods\ud 148 patients underwent SPECT stress MPI using a fixed Tc-99m tetrofosmin tracer dose. Measured photon counts were normalized to administered tracer dose and scan time and were correlated with body weight, body mass index, and mass per length to find the best predicting parameter. From these data, a protocol to provide constant image quality was derived, and subsequently validated in 125 new patients.\ud \ud \ud Results\ud Body weight was found to be the best predicting parameter for image quality and was used to derive a new dose formula; Aadmin (MBq) = 223·body weight (kg)0.65/Tscan (min). The measured photon counts decreased in heavier patients when using a fixed dose (P < .01) but this was no longer observed after applying a body-weight-dependent protocol (P = .20).\ud \ud \ud Conclusions\ud Application of a patient-specific protocol resulted in an image quality less depending on patient’s weight. The results are most likely independent of the type of SPECT camera used, and, hence, adoption of patient-specific dose and scan time protocols is recommended

Health promotion profile of youth sports clubs in Finland: club officials' and coaches' perceptions

The purpose of this article is to examine the current health promotion orientation of youth sports clubs in Finland in view of the standards created previously for the health promoting sports club (HPSC). Ninety-seven youth sports clubs participated, and 273 sports club officials and 240 coaches answered the questionnaires. To describe clubs health promotion orientations, an HPSC index was created. The HPSC index was formulated on sub-indices by factor analysis. The sub-indices were: policy, ideology, practice and environment indexes. The results indicate that youth sports clubs are fairly health promoting in general. On average, the clubs fulfilled 12 standards for HPSC out of 22. Every fourth club was categorized as higher health promoting (≥ 15 fulfilled standards), and every third as lower health promoting (<11 fulfilled standards). The variation between clubs was wide. The clubs that had been recognized as exemplary and hence certified by the Young Finland Association were more likely to recognize health promotion than non-certified clubs (OR = 2.36, p = 0.016). The sports club officials were twice as likely to evaluate their clubs as higher health promoting than the coaches (OR = 2.04, p = 0.041). Under the sub-indices, ideologies were recognized best, others less. These findings indicate that minority of the youth sports clubs have realized health promotion comprehensively as a part of their activities. There is a lot of need for development, especially in the area of health promotion policies and practices. The instruments used proved valid and reliable and can therefore be recommended for international use

The effects of a controlled worksite environmental intervention on determinants of dietary behavior and self-reported fruit, vegetable and fat intake

BACKGROUND: Eating patterns in Western industrialized countries are characterized by a high energy intake and an overconsumption of (saturated) fat, cholesterol, sugar and salt. Many chronic diseases are associated with unhealthy eating patterns. On the other hand, a healthy diet (low saturated fat intake and high fruit and vegetable intake) has been found important in the prevention of health problems, such as cancer and cardio-vascular disease (CVD). The worksite seems an ideal intervention setting to influence dietary behavior. The purpose of this study is to present the effects of a worksite environmental intervention on fruit, vegetable and fat intake and determinants of behavior. METHODS: A controlled trial that included two different governmental companies (n = 515): one intervention and one control company. Outcome measurements (short-fat list and fruit and vegetable questionnaire) took place at baseline and 3 and 12 months after baseline. The relatively modest environmental intervention consisted of product information to facilitate healthier food choices (i.e., the caloric (kcal) value of foods in groups of products was translated into the number of minutes to perform a certain (occupational) activity to burn these calories). RESULTS: Significant changes in psychosocial determinants of dietary behavior were found; subjects at the intervention worksite perceived more social support from their colleagues in eating less fat. But also counter intuitive effects were found: at 12 months the attitude and self-efficacy towards eating less fat became less positive in the intervention group. No effects were found on self-reported fat, fruit and vegetable intake. CONCLUSION: This environmental intervention was modestly effective in changing behavioral determinant towards eating less fat (social support, self-efficacy and attitude), but ineffective in positively changing actual fat, fruit and vegetable intake of office workers