Evaluation of the inner-surface morphology of an artificial heart by acoustic microscopy

The total artificial heart (TAH) is being developed for permanent replacement of the natural heart instead of heart transplantation. The need for detecting the material fatigue in the TAH is increasing in order to guarantee long-term use. In this study, the inner surface morphology of the TAH was evaluated by a specially developed scanning acoustic microscope (SAM) system operating in the frequency range of 100-200 MHz. The inner sac of our TAH consisted of polyvinylchloride coated with polyurethane, and the SAM investigations were performed before and after the implantations in goats. The amplitude images of the SAM demonstrated protein adhesion on the inner surface of the TAH after the animal experiment, and the phase images showed distortion of the wall with spatial resolution of 0.2 microm. These results suggest the feasibility of a high-frequency ultrasound for evaluating the material fatigue of TAH.     

The occurrence of phthalic acid esters in various samples of commercially available sodium chloride injections (Indian Pharmacopoeia)

Conclusive evidence for the presence of di(2-ethylhexyl) phthalate (DEHP) in 15 out of 17 commercially available sodium chloride injection (Indian Pharmacopoeia) samples was obtained and concentration levels as high as 11.0 mg/500 ml of saline were detected. The presence of such contaminants in i.v. fluids, avoidable by the institution of appropriate quality control measures before manufacturing and marketing, is a matter of serious concern. Stipulated specifications in different pharmacopoeias are meant only to ensure sterility and pyrogenicity, and it is advisable that cognisance be taken of the presence of toxic contaminants e.g. di(2-ethylhexyl) phthalate.     

Adsorption of human and porcine insulins to intravenous administration sets

A comparison between human and porcine insulins with regard to their adsorption to administration sets was performed. A¹²⁵I-mono(A14)-iodinated insulin was used to follow the adsorption phenomenon over time and the adsorption was quantified with radioimmunoassays of unlabelled insulin. The obtained data were similar for both methods. No relevant difference in adsorption was found between human and porcine insulin. Both insulins showed a significantly more pronounced initial drop in delivered insulin when polyethylene tubing was used. After 3 h a steady state was reached, resulting in the administration of a more predictable dose. Particularly in the initial phase an important reduction in the amount of both insulins actually delivered to the patient was observed when compared to the expected amount as calculated from the concentration present in the container and the infusion rate.Therefore, the mainstay in treatment of a patient with ketoacidosis remains frequent serum glucose measurement and making appropriate infusion rate adjustments on that basis.     

新型聚合物／液晶复合膜的研究：Ⅰ.膜材料对气体分离性能的影响

用顺丁橡胶，丁苯橡胶及聚氯乙烯与带有ＣＨ２＝ＣＨ－端基的液晶化合物共混，溶液浇铸法成膜，橡胶／液晶复合膜利用Ｓ２Ｃｌ２蒸气交联。用体积法测定膜的透气性，着重研究了不同基质材料及不同液晶类型对气体分离性能的影响。结果表明顺丁橡胶／液晶复合膜的透气系数最高，且分离性能也最好。     

Small airways function in workers processing polyvinylchloride

Summary In a polyvinyl chloride (PVC) processing plant, 20 workers employed as machine attendants and calender operators, and thus exposed to PVC thermal degradation products (PTDP) and phthalic acid esters (PAE; up to 2 mg/m³), were studied. The control group was 19 unexposed workers. The exposed subjects had more symptoms from eyes and upper air-ways than the controls, probably mainly associated with PTDP. Two (10%) exposed workers had mild work-related asthma vs no control; five (25%) vs one (5%) symptoms of unspecific bronchial hyperreactivity. One exposed subject had a significantly raised level of IgG against phthalic anhydride, indicating that sensitization can occur in PVC processing. No significant differences were found between exposed and control subjects with regard to spirometry (VC, FEV₁, FEF₅₀, FEF₇₅) or volume of trapped gas (VTG, an indicator of small airways disease) before or after metacholine inhalation. Thus, we could not find effects of PTDP or PAE on the small airways.     

Control of solvent use in medical devices by proton transfer reaction mass spectrometry and ion molecule reaction mass spectrometry

A homemade proton transfer reaction mass spectrometer (PTR-MS) and a commercial ion molecule reaction mass spectrometer (IMR-MS) have been applied to detect volatile organic compounds (VOCs) in the packaging bags of infusion sets made of polyvinylchloride (PVC) plastic. The most abundant characteristic ions in the PTR-MS and IMR-MS measurements are observed at m/z 99 and 98 respectively, which are the results of soft ionizations that a residual chemical undergoes the proton transfer reaction in PTR-MS and the charge transfer reaction in IMR-MS. On the basis of ionic intensity dependence on the reduced-field in the PTR-MS investigation, the residue can be unambiguously identified as cyclohexanone, a commonly used adhesive agent in PVC medical device manufacture. Quantitative measurement by PTR-MS shows that concentrations of cyclohexanone in the packages of two types of infusion sets are 11 and 20 ppm respectively. Due to fast response, absolute concentration detection, and high sensitivity, the PTR-MS and IMR-MS detection methods are proposed for the quality control of medical devices including the detection of illegal or excessive uses of chemical solvents like cyclohexanone.     

Upcoming Meetings

This journal welcomes comments from all those involved in artificial organs as researchers, developers, or users. We would like to hear of your experiences. Please send all Communications to the Editorial Office.     

Pathobiochemical response of tracheobronchial lymph nodes following intratracheal instillation of Polyvinylchloride dust in rats

PVC dust, following a single intratracheal instillation (25 mg/rat), was substantially cleared through the lymphatic circulation and progressively accumulated in the tracheobronchial lymph nodes (TBLN) in a time-dependent manner for up to 1 year. The tissue response in TBLN during 60–270 days post-instillation of PVC dust was characterized by progressive increase in total organ fresh weight, dry weight, DNA, RNA and protein contents, concurrent with the proliferation of macrophages and hyperplasia of reticular cells. Active phagocytosis and enhanced hydrolytic activity in TBLN was evident around 270 days post-instillation by the appearance of PVC-laden macrophages near and within the dust foci, and increased activity of acid phosphatase, DNAse, RNAse and -glucuronidase. PVC dust caused degeneration of macrophages, and consequent release of hydrolytic enzymes resulted in limited cytotoxicity without inducing reticulination and fibrosis in the TBLN. The histology and clinical biochemistry of liver, kidney, spleen and serum were not altered and there were no detectable PVC particles in these tissues at up to 365 days. It is therefore concluded that lymphatic clearance of intratracheally instilled PVC dust results in its accumulation and mild foreign body reaction in TBLN which is non-fibrogenic at up to 365 days post-instillation.     

In vitro cytotoxic effects of secondary metabolites of DEHP and its alternative plasticizers DINCH and DINP on a L929 cell line

Background

Phthalic acid esters are widely used to improve the plasticity of PVC in medical devices (MD). The most famous plasticizer is DEHP, whose use in medical devices has been contested by the European authorities since 2008. Several alternative plasticizers are being considered to replace DEHP, such as DEHT, TOTM, DINP or DINCH, but they are also released from the PVC throughout their life cycle and are metabolized in the same way as DEHP.

Complement Metabolism During Membrane Plasma Separation

Abstract: Because it has been found that some plasma separator membranes can activate complement in serum, this study focuses on the behavior of complement during actual membrane plasmapheresis. Complement metabolism in subjects undergoing membrane plasma separation with three different prototypic devices was studied. Complement activation was judged by crossed immunoelectrophoretic analysis of C3 in plasma. A cellulose acetate separator employed with heparin as the anticoagulant caused extensive C3 conversion (up to 50%) in separated plasma. A polysulfone separator used with citrate, and a polyvinylchloride derivative separator employed with heparin plus citrate, caused only small amounts of C3 conversion (0–10%) in separated plasma. C3 conversion in the cellulose acetate separator was reduced when citrate was included in the anticoagulant regimen, whereas C3 conversion in the polyvinylchloride derivative separator was increased when citrate was omitted. Activation of complement by the membrane material may occur during membrane plasma separation. Selection of membranes judged weakly activating by in vitro screening and the use of citrate anticoagulation would appear to minimize complement activation in membrane plasma separators.