Thoracic electric impedance and fluid balance during aortic surgery

Indices of fluid balance were evaluated during and after aortic surgery in 16 consecutive patients. Thoracic electrical impedance (TI), heart rate (HR), central venous (CVP), pulmonary artery mean (PAMP), pulmonary wedge (PWP) and mean arterial (MAP) pressures as well as fourteen arterial and venous blood gas variables were followed. Consistent with a reduction of TI during the operation, fluid balance was in excess, and it remained elevated on the first postoperative morning. The HR, MAP and PWP remained stable, while CVP and PAMP decreased. Of the determined variables only TI revealed a meaningful correlation to fluid balance (rho = -0.41; p < 0.01). The results indicate that while central venous and pulmonary artery mean pressures gave the impression of a volume deficit, the positive fluid balance was mirrored by thoracic electrical impedance.     

Characterization of allergoids from ovalbumin in vitro and in vivo

Several in vivo and in vitro methods for monitoring immunological properties of two allergoids obtained by formaldehyde treatment of ovalbumin (OA) were developed. The calculated molecular weight of allergoids was 80 kD (OA-F1) and 165 kD (OA-F2), respectively. The allergenic activity in vitro of allergoids in mast-cell histamine release assay was 1000 times lower than of OA. Both allergoids showed reduced ability to induce passive cutaneous anaphylaxis in the Sprague-Dawley rats or systemic anaphylaxis in Dunkin-Harley guinea-pigs. The ability of OA and allergoids to bind to the OA-specific IgE antibodies was measured in vivo by the inhibition of passive cutaneous anaphylaxis (PCA-inhibition). Allergoid binding to IgE was 51-66% lower than the native allergen. Moreover, the avidity of OA-specific IgG antibodies, measured by ELISA-inhibition, for allergoids and allergen was of the same order. Allergoids induced a different pattern of humoral immune response from that, induced by the native allergen. Thus, after immunization of BALB/c mouse, both allergoids induced a higher production of IgG and a lower production of IgE than OA, only OA-F2 induced a lower production of IgG1. The differences in the IgA response to the immunogens was not significant. Delayed hypersensitivity studies in the BALB/c mouse showed that allergoids were 5- to 12-times less effective in inducing a cell-mediated immune response than OA. The present study provides a battery of immunological methods for preclinical testing of modified allergens.     

Surfactant replacement therapy in acute respiratory distress syndrome from viral pneumonia

A modified natural surfactant was administered to a patient with life-threatening adult respiratory distress syndrome caused by viral pneumonia. Subsequently, there was a marked improvement in gas exchange. In order to assess the mechanism for improved oxygenation, computed tomography of the lungs was done. Quantitative analysis of the scans taken before and after surfactant administration indicates that improvement in gas exchange was largely due to the expansion of underinflated and collapsed lung areas. Although this is a single case report, it provides insight into the possible beneficial effect of instilled surfactant in severe respiratory distress from viral pneumonia.     

Production of proteinase A by Saccharomyces cerevisiae in a cell-recycling fermentation system: experiments and computer simulations

Overproduction of proteinase A by recombinant Saccharomyces cerevisiae was investigated by cultivations in a cell-recycling bioreactor. Membrane filtration was used to separate cells from the broth. Recycling ratios and dilution rates were varied and the effect on enzyme production was studied both experimentally and by computer simulations. Experiments and simulations showed that cell mass and product concentration were enhanced by high ratios of recycling. Additional simulations showed that the proteinase A concentration decreased drastically at high dilution rates and the optimal volumetric productivities were at high dilution rates just below washout and at high ratios of recycling. Cell-recycling fermentation gave much higher volumetric productivities and stable product concentrations in contrast to simple continuous fermentation.     

The use of cantilever bridges

Replacement of missing teeth with fixed bridgework often involves producing full crown retainers on teeth on both sides of an edentulous space. Unfortunately, this approach can result in the destruction of much healthy tooth tissue, and the clinician must balance the benefits of replacing missing teeth with the amount of tooth preparation required. Current thinking in restorative dentistry places the preservation of tooth tissue at a premium, and most practitioners are happy to use techniques that embrace this philosophy. Because of this, cantilever bridges have an increasing role in dental practice, where the replacement for a missing tooth or teeth has one or more abutments on only one side of the edentulous space, being unsupported at the other. Cantilever bridges fall into several types, depending on the number of abutments and types of retainers. This article describes the various cantilever bridge designs, considers the biomechanics of these restorations, and provides guidelines for their clinical use.     

Economic and ecological aspects of plasma surface engineering

For new developments such as plasma surface technologies, it is first necessary to prove their scientific possibilities and limits. Therefore it is mainly questions of process understanding and process handling, quality of the substrate and coating as well as its interactions which are considered and discussed.

To use these technologies in industry it is also necessary to consider ecological aspects as well as economic and marketing aspects. For a scientist at first these aspects are not as important.

An overview of different economic aspects of the application of plasma surface technologies is presented by considering the following: investment and running costs of plants; costs of process development for special applications; comparison of different technologies; certainty and reproducibility of the coating technologies; cost and profit balance of coated work pieces; costs of marketing.

Recently, the importance of the ecological aspects of industrial technologies has increased greatly. In most cases these questions are closely linked to the economic aspects. Nearly all ecological problems can be solved and handled, but the costs for this are increasing greatly. Although the laws currently differ in different countries, in future the laws everywhere will become more strict. The main concerns of the application and handling of a plasma assisted process are for example the use or production of toxic media, security of plants for the staff and for the environment, and handling of used coated material.     

Parameters affecting the use of the lac repressor system in eukaryotic cells and transgenic animals

Elements of the lactose operon were used to study parameters affecting gene expression in cultured cells and transgenic animals. A Lac repressor protein containing a nuclear transport signal was shown to inhibit expression of a reporter gene by interacting with lac operator sequences. In cultured cells, operator sequence, operator placement and induction parameters were all shown to be important for obtaining tight repression of a reporter gene followed by high level expression upon induction. Induction levels were also dependent on the reporter gene, with the luciferase gene yielding higher induction levels than the chloramphenicol acetyltransferase gene. In transgenic animals, the lacI mRNA was not detected in the C57BL/6 mouse strain until the animal was exposed to a demethylating agent. After 5-azacytidine treatment, expression of lacI mRNA was detected in the brain, heart, kidney, lung and ovary. In the FVB transgenic mouse strain, expression of lacI mRNA was detected without 5-azacytidine treatment in the kidney, liver, lung, and testes. Preliminary experiments with double transgenic animals containing both lacI and operator/luciferase transgenes showed a decrease in luciferase expression compared to the luciferase-only animals in both tissue extracts and transgenic fetal primary cultures, although IPTG induction was not achieved in these animals or primary cultures. The applicability and challenges of the system for regulation of gene expression are discussed.     

Biochemical identification of transmembrane segments of the Ca(2+)-ATPase of sarcoplasmic reticulum

The transmembrane segments of sarcoplasmic reticulum Ca(2+)-ATPase were determined by trypsinization of cytoplasmic side-out intact sarcoplasmic reticulum vesicles. The membrane portion of tryptic digest comprising the transmembrane fragments, joined by the intravesicular segments, was separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after labeling with fluorescein 5-maleimide in the presence of sodium dodecyl sulfate. In this way, seven fluorescent bands of tryptic fragments below 11 kDa were observed which were derived from 4 pairs of membrane spanning segments and one hydrophobic sequence at the C-terminal end. Two peptides of 10.8 and 10.6 kDa had the identical N-terminal sequence beginning at Glu826, representing the transmembrane segments M7 and M8 and their connecting loop. A band at 8.1 kDa contained one peptide beginning at Tyr36 (M1/loop/M2). A 7.7-kDa peptide starting at Leu253 (M3/loop/M4) and a 7.3-kDa peptide beginning at Ala752 (M5/loop/M6) were also observed. A band at 6.7 kDa contained two peptides, one beginning at Ser48 (M1/loop/M2) and another beginning at Tyr763 (M5/loop/M6). In addition, a 4-kDa peptide beginning at Met925 was observed. The size of this peptide did not allow for a complete pair of transmembrane segments, but this peptide could have been derived from trypsinolysis between the last pair of membrane spanning segments. These data therefore provide biochemical evidence for at least 8 transmembrane segments and perhaps two more at the C-terminal end of the enzyme.