The kinetics of the tissue distribution of silver nanoparticles of different sizes.

Blood kinetics and tissue distribution of 20, 80 and 110 nm silver nanoparticles were investigated in rats up to 16 days after intravenous administration once daily for 5 consecutive days. Following both single and repeated injection, silver nanoparticles disappeared rapidly from the blood and distributed to all organs evaluated (liver, lungs, spleen, brain, heart, kidneys and testes) regardless of size. The 20 nm particles distributed mainly to liver, followed by kidneys and spleen, whereas the larger particles distributed mainly to spleen followed by liver and lung. In the other organs evaluated, no major differences between the sizes were observed. Size-dependent tissue distribution suggests size-dependent toxicity and health risks. Repeated administration resulted in accumulation in liver, lung and spleen, indicating that these organs may be potential target organs for toxicity after repeated exposure. A physiologically based pharmacokinetic (PBPK) model for nanoparticles which describes the kinetics of silver nanoparticles was developed. Model parameter values were estimated by fitting to data. No clear relation between parameter values and corresponding particle diameters became apparent.

Annex II technical documentation assessed.

Annex II of the Medical Device Directive (MDD) is used frequently by manufacturers to obtain CE-marking. This procedure relies on a full quality assurance system and does not require an assessment of the individual medical device by a Notified Body. An investigation into the availability and the quality of technical documentation for Annex II devices revealed severe shortcomings, which are reported here.

Study to determine the presence of antipolymer antibodies in a group of Dutch women with a silicone breast implant.

OBJECTIVE: To determine whether there exists a population of Dutch women with a high prevalence of antipolymer antibodies (APA) and severe health complaints/symptoms, and exposure to a silicone breast implant (SBI). As the antigen-specific nature of the antipolymer antibody has not yet been established, we refer to the term polymer binding immunoglobulins. METHODS: The study population was selectedfrom a voluntary registry of SBI recipients of a Dutch consumers organisation. The final selection was based on the severity of self-reported complaints in a questionnaire. A total of 42 SBI recipients were included in the study, clinically examined and blood samples were obtained. RESULTS: In 12 of 42 SBI recipients an increase in the level of polymer binding immunoglobulins was detected compared to a negative reference sample, 3 of these 12 showing a positive and 9 a weakly positive response. In 3 out of 12 non-SBI recipients, included for control on the performance of the APA assay, an increased level of polymer binding immunoglobulins was demonstrated, 2 of these 3 showing a positive and 1 a weakly positive response. The study population of SBI recipients was categorised in severity subgroups (limited, mild, moderate, advanced) based on the fuctional capacity and the physicians general assessment of pain and disease activity. Most (34 of 42) SBI recipients belonged to the limited severity subgroup. CONCLUSION: Our methods failed to select a group of severely symptomatic Dutch SBI recipients reported to have a high prevalence of polymer binding antibodies. A discrepancy was present between the self reported severe complaints and the observed mild clinical symptoms. In the group of SBI recipients with self reported severe complaints recruited we did not find a high prevalence of polymer binding immunoglobulins. SBI exposure (mean 17 years) did not result in induction of polymer binding immunoglobulins in this minimal symptomatic study group.

Medical devices manufactured from latex: European regulatory initiatives.

In Europe the marketing of medical devices manufactured from latex is regulated by directives describing the essential (safety) requirements that products have to fulfill to obtain marketing approval. This paper describes the general requirements for marketing medical devices in Europe and, more specifically, the requirements for products manufactured from natural rubber latex. The requirements for marketing medical devices can be fulfilled by using the relevant harmonized European standards. These standards are regularly under revision to incorporate the latest scientific developments. For certain devices, for example, latex medical (examination and surgical) gloves, specific standards have been published. Medical devices manufactured from latex pose a serious problem because of the risk of induction of allergy both against the latex proteins inherently present (type I or immediate type allergy) and against chemicals added during processing (type IV or delayed type hypersensitivity) present as residues in the latex products. So, besides requirements for product quality in terms of barrier properties, strength, and sterility, the main focus consists of the allergy-inducing properties of the latex products. Recent developments have reopened the discussion on the value of total protein versus allergen determination in latex medical gloves. However, as long as minimal levels needed for both sensitization and elicitation have not been established, a safe maximum level for leachable proteins/allergens in latex products cannot be determined. A European Commission guidance document on the latex allergy problem is currently being drafted by experts from Competent Authorities.

Studies on the efficacy of hyperbaric rendering procedures in inactivating bovine spongiform encephalopathy (BSE) and scrapie agents.

The efficacy of the procedures in use at the two rendering plants in the Netherlands was assessed on a laboratory-scale using procedures that simulated the pressure cooking part of the rendering process. A pool of bovine spongiform encephalopathy (BSE)-infected brainstem from the United Kingdom and a pool of scrapie-infected brainstem from Dutch sheep were used to spike the rendering materials. The mixtures were subjected to various time-temperature combinations of hyperbaric heat treatment related to the conditions used in Dutch rendering plants in the early 1990s, and to the combination of 20 minutes at 133 degrees C required by the EU Directive on rendering of 1996. The efficacy of the procedures in inactivating BSE or scrapie infectivity was measured by titrating the materials before and after heat treatment in inbred mice, by combined intracerebral and intraperitoneal inoculations at limiting dilutions. Two independent series of experiments were carried out. The design of the study allowed for minimum inactivations of up to 2.2 log (2.0 in the second series) to be measured in the diluted infective material and 3.1 log in the undiluted material. After 20 minutes at 133 degrees C there was a reduction of BSE infectivity of about 2.2 log in the first series (with some residual infectivity detected), and in the second series more than 2.0 log (with no residual infectivity detected). With undiluted brain material there was an inactivation of about 3.0 log (with some residual infectivity detected). With the same procedure, scrapie infectivity was reduced by more than 1.7 log in the first series and by more than 2.2 log in the second series. With undiluted brain material there was an inactivation of more than 3.1 log. In each case no residual scrapie infectivity was detected. The BSE agent consistently appeared to be more resistant to heat inactivation procedures than the scrapie agent, particularly at lower temperatures and shorter times.