Viscosity measurements on very small capillary blood samples.

Viscosity measurements on very small capillary blood samples could be of considerable clinical interest. We have developed an oscillating viscometer for very small volumes, which consists of a glass capillary containing 7 mul of blood, which is part of an oscillating torsional resonator. The damping of the sinusoidal oscillations depends on the density and viscosity of the fluid, which allows blood viscosity measurements. The instrument was first evaluated in comparison with a standard blood viscometer (Contraves LS 30). Blood from healthy volunteers anticoagulated with EDTA was adjusted to hematocrit levels of 20, 30, 40, 50, and 60%, respectively. A strong correlation was found between hematocrit and oscillating viscosity (y=0.17x-2.05, r=0.969, p<0.0001) and between oscillating and conventional high shear viscosity (y=1.11x-0.62, r=0.971, p<0.0001). Blood viscosity measured in venous or capillary blood of normal subjects was similar (p=0.63). Bedside viscosity measurements on capillary blood drawn from a finger prick during routine blood glucose measurements in patients with diabetes mellitus showed lower blood viscosity than controls (3.62+/-0.87 vs 4.79+/-0.59 mPa.s, p=0.0007), which is in contrast to earlier publications, and may be explained by the lower hematocrit in our diabetic patients (34.7+/-6.0% vs. 43.1+/-1.9%, p<0.0001). Blood viscosity was independent of the actual glucose level (range 3-17 mmol/l). Capillary blood anticoagulated with EDTA was drawn by heel prick from 23 newborns. Blood viscosity was higher (5.66 +/-2.47 mPa.s) than in adult controls (see above), which could be explained by the dependence on the higher hematocrit (46.4 +/-8.6%). We conclude that viscosity measurements can be made on very small samples such as capillary blood from diabetic patients or newborn babies with this new oscillating viscometer. It remains to be determined if such new informations have clinical implications.

Some methodological studies on effector cells in the lymphocyte-dependent cytotoxic antibody assay.

A method of direct freezing was found to be reliable for storage of the effectors for the LDA assay, though there is a considerable loss of cells. In order to get immunologically active K cells after thawing, an important step is to leave the cells to recuperate overnight in an appropriate medium before use. A short-term storage of fresh effectors is also possible. The use of a pool of effector cells from a minimum of 3 random blood donors obviates the selection of HL-A types furthermore permits a saving of the amount of serum used. Enrichment of a B cell population by removing the cells capable of forming spontaneous rosettes with SRBC was not found to enhance cytotoxicity. Pretreatment of cells with pronase, trypsin and neuraminidase did not significantly enhance their effector activity, while papain treated cells showed a systematically increased specific lysis.

Environmental impacts of the Swiss collection and recovery systems for Waste Electrical and Electronic Equipment (WEEE): a follow-up.

While Waste Electrical and Electronic Equipment (WEEE) collection and recovery have significantly gained in importance all over Europe in the last 15years, comprehensive studies assessing the environmental loads and benefits of these systems still are not common. In this paper we present the results of a combined material flow analysis and life cycle assessment study, which aimed to calculate the overall environmental impacts of collection, pre-processing and end-processing for the existing Swiss WEEE collection and recovery systems, as well as of incineration and landfilling scenarios, in which the same amount of WEEE is either incinerated in a an MSWI plant or landfilled. According to the calculations based on the material flow data for the year 2009 and a new version of the ecoinvent life cycle inventory database (ecoinvent v2.01), collection, recovery and disposal result in significantly lower environmental impacts per t of WEEE for midpoint indicators such as global warming or ozone depletion and the endpoint indicator Eco-Indicator '99 points. A comparison between the environmental impacts of the WEEE recovery scenarios 2009 and 2004, both calculated with ecoinvent v2.01 data, shows that the impacts per t of WEEE in 2009 were slightly lower. This appears to be mainly due to the changes in the treatment of plastics (more recycling, less incineration). Compared to the overall environmental impacts of the recovery scenario 2004 obtained with an old version of ecoinvent (ecoinvent v1.1), the calculation with ecoinvent v2.01 results in an increase of the impacts by about 20%, which is primarily the consequence of a more adequate modeling of several WEEE fractions (e.g. metals, cables or CRT devices). In view of a further increase of the environmental benefits associated with the Swiss WEEE collection and recovery systems, the recovery of geochemically scarce metals should be further investigated, in particular.

The major protein import receptor of plastids is essential for chloroplast biogenesis.

Light triggers the developmental programme in plants that leads to the production of photosynthetically active chloroplasts from non-photosynthetic proplastids. During this chloroplast biogenesis, the photosynthetic apparatus is rapidly assembled, mostly from nuclear-encoded imported proteins, which are synthesized in the cytosol as precursors with cleavable amino-terminal targeting sequences called transit sequences. Protein translocon complexes at the outer (Toc complex) and inner (Tic complex) envelope membranes recognize these transit sequences, leading to the precursors being imported. The Toc complex in the pea consists of three major components, Toc75, Toc34 and Toc159 (formerly termed Toc86). Toc159, which is an integral membrane GTPase, functions as a transit-sequence receptor. Here we show that Arabidopsis thaliana Toc159 (atToc159) is essential for the biogenesis of chloroplasts. In an Arabidopsis mutant (ppi2) that lacks atToc159, photosynthetic proteins that are normally abundant are transcriptionally repressed, and are found in much smaller amounts in the plastids, although ppi2 does not affect either the expression or the import of less abundant non-photosynthetic plastid proteins. These findings indicate that atToc159 is required for the quantitative import of photosynthetic proteins. Two proteins that are related to atToc159 (atToc120 and atToc132) probably help to maintain basal protein import in ppi2, and so constitute components of alternative, atToc159-independent import pathways.

The use of directly frozen cells in LDA assay.

A method of direct freezing is described which requires a cryoprotective medium consisting of human AB serum and DMSO, an ultra-low temperature freezer and a liquid-nitrogen refrigerator. Fresh and directly frozen cells were compared in the LDA assay. Direct freezing is quite reliable for normal lymphocytes, PHA transformed lymphocytes or leukaemic blasts used as targets. However, a controlled freezing procedure may be necessary to preserve the effector cell activity.