In vitro display technologies: novel developments and applications

In vitro display techniques are powerful tools to select polypeptide binders against various target molecules. Novel applications include maturation of protein affinity and stability, selection for enzymatic activity, and the display of cDNA and random polypeptide libraries. Taken together, these display techniques have great potential for biotechnological, medical and proteomic applications.

Inhibition of ongoing allergic reactions using a novel anti-IgE DARPin-Fc fusion protein

BACKGROUND

Aggregation of the high-affinity IgE receptor (FcεRI) with the low-affinity IgG receptor (FcγRIIb) on basophils or mast cells has been shown to inhibit allergen-induced cell degranulation. Molecules cross-linking these two receptors might therefore be of interest for the treatment of allergic disorders. Here, we demonstrate the generation of a novel bispecific fusion protein efficiently aggregating FcεRI-bound IgE with FcγRIIb on the surface of basophils to prevent pro-inflammatory mediator release.

METHODS

Alternative binding molecules recognizing receptor-bound human IgE were selected from DARPin (designed ankyrin repeat protein) libraries. One of the selected DARPins was linked to the Fc-part of a human IgG(1) antibody for binding to FcγRIIb.

RESULTS

The resulting anti-IgE DARPin-Fc fusion protein was not anaphylactogenic and inhibited allergen-induced basophil activation in whole blood assays. Both binding moieties of the fusion protein, namely the anti-IgE DARPin as well as the IgG(1) Fc-part, were required to achieve this inhibitory effect. Most importantly, inhibition was faster and more efficient than with Omalizumab, a humanized anti-IgE antibody currently used for the treatment of severe asthma.

CONCLUSION

This novel anti-IgE DARPin-Fc fusion protein might represent a potential drug candidate for preventive or immediate treatment of allergic reactions.

Capillary leakage complicated by compartment syndrome necessitating surgery

A single episode of systemic capillary leak syndrome is reported in a HIV-positive patient. The shock had necessitated the infusion of large amounts of fluid with concomitant diffuse swelling and weight gain leading to compartment syndrome of both legs. This required surgical relief. The initial high hematocrit (62%) and low serum protein concentration (48 g/l) with normal factor V (molecular weight above 300,000) concentrations are the hallmark of capillary leak when they are associated with hypovolemic shock. It must be emphasized that fluid resuscitation may worsen the muscle damage with ultimate compartment syndrome. Therefore, it appears reasonable to monitor muscular pressure during volume expansion in patients with capillary leak syndrome, severe shock and muscular swelling.

Phospholipase and prophospholipase activities in bronchoalveolar lavage fluid in severe acute pulmonary disease with or without ARDS

Bronchoalveolar lavages were performed in 21 patients undergoing mechanical ventilation: Group I: coma due to sedative overdose (11 cases), without pulmonary impairment, serving as control group; Group II: severe acute pulmonary disease without ARDS (5 cases); Group III: patients with ARDS (5 cases). In the recovered fluid we measured: total proteins (P) and phospholipids (PL), phospholipasic (PLase) and prophospholipasic (PPLase) activities. In ARDS group, considerable increase of P, (p less than 0.001), and a doubling of PL (p less than 0.02) was found. Total PLase activity was present in all three groups, with a higher mean level in Group III (p less than 0.01). PPLase activities were low or undetectable in four patients of this group. PLase/PL ratio was increased in acute respiratory insufficiency, with or without ARDS, suggesting an increase of surfactant catabolism. The decrease of this ratio when pulmonary function improved, or its increase after deterioration suggest that it is related to changes of surfactant.

Polycythemia in chronic obstructive pulmonary disease. A study of serum and urine erythropoietin and medullary erythroid progenitors

In order to investigate the mechanism of polycythemia in chronic obstructive pulmonary disease (COPD), serum and urinary levels of erythropoietin and medullary erythroid progenitors were studied in 21 patients; nine were nonpolycythemic (hematocrit, 39 +/- 4 percent; red blood cell [RBC] mass, 28 +/- 5 ml/kg; forced expiratory volume in one second [FEV1], 0.6 +/- 0.1 L), and 12 patients were polycythemic (hematocrit, 52 +/- 7 percent; RBC mass, 46 +/- 7 ml/kg; FEV1, 0.9 +/- 0.3 L). Hypoxia was severe in both groups, with mean arterial oxygen pressure of 47 mm Hg. The following parameters of tissue oxygenation were not significantly different between the two groups: arterial and mixed-venous oxygen saturations; cardiac output; oxygen utilization coefficient; 2, 3-diphosphoglycerate, and carboxyhemoglobin level. The level of erythropoietin was measured by bioassay in vitro. The level was increased in the serum of 85 percent (18) and in the urine of 38 percent (8) of the patients. There was no significant difference between the nonpolycythemic and polycythemic groups. Without exogenous erythropoietin, none of the subjects showed spontaneous colonies of erythroid progenitors. The addition of one unit of erythropoietin induced a similar normal proliferation of erythroid progenitors in both groups. The absence of adaptative polycythemia in the nonpolycythemic group with severe hypoxia was seemingly related neither to a quantitative deficit of erythropoietin nor to a lack of sensitivity of erythroid progenitors to its action.

[Efficacy and tolerance of Elohes in plasma exchanges]

This study aimed to compare two plasma substitution regimens used during plasma exchanges (PE). It was a prospective cross-over randomized trial. Each patient (n = 12) had two PE at a 48 h interval. During one PE, only albumin was administered (PEA), and during the other one, equal volumes of albumin and low molecular weight hydroxyethylstarch (HES) (Elohes) were given (PEA+E). The order in which these different protocols were used was random. Plasma was separated by filtration, and the total volume extracted was one and a half the plasma volume. The parameters recorded every 15 min until 1 h after the end of PE, were heart rate, blood pressure and central venous pressure (CVP). Plasma volume, calculated from the mean body haematocrit and blood volume, was measured before and after PE. The clinical and biological tolerance of the rapid infusion of a large volume of HES was also assessed. PE characteristics were similar in both groups. For PEA and PEA+E, PE lasted 152 +/- 21 min and 154 +/- 25 min; the plasma volume extracted was 3,907 +/- 772 ml and 3,933 +/- 717 ml; the volume of plasma substitute infused was 4,097 +/- 617 ml and 3,933 +/- 717 ml, respectively. As haemodynamic and biochemical values were not significantly different in both groups, they were pooled together irrespective of the order of PE.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of high-performance liquid chromatography and polyclonal fluorescence polarization immunoassay for the monitoring of midazolam in the plasma of intensive care unit patients

Midazolam (M) is used as an induction agent for anesthesia. The main metabolite is alpha-hydroxymidazolam (OM), which is pharmacologically active. Use of M for sedation is a recent application, rapidly gaining favor. Monitoring of the level of sedation is fundamental in that an excessive and prolonged effect is associated with the risk of complications. Thus, it was felt both necessary and useful to measure circulating M levels. We compared a high-performance liquid chromatography (HPLC) assay with fluorescence polarization immunoassay (FPIA) for the measurement of M in the serum of 138 sedated patients in the intensive care unit (i.e., 179 samples). Response of the OM was also assessed. The degree of crossover of the metabolite was between 76.8 and 32.7%. The equation of the regression line for sigma HPLC (i.e., the sum M + OM) versus FPIA was TDx = 1.1585 sigma HPLC + 143.42 (R = 0.966). The 95% confidence interval for the slope was 1.1551, 1.1619. The regression slope differed significantly from 1 (p < 0.001) and shows that FPIA measurements overestimated concentrations obtained by HPLC on the order of 19%. The discrepancy between the two techniques was all the more notable when concentrations were > 1,000 ng/ml. The relative selectivity of Abbott industrial reagent in terms of benzodiazepines leads to the identification of what might be called a midazolam-like (M-like) activity covering both M and OM. The development of a global FPIA method for measurement of this M-like activity in sedated patients provides a satisfactory solution to the question raised.

Temocillin treatment of serious infections due to gram-negative bacilli in an intensive care unit

In a group of 27 severely ill patients in an intensive care unit, 40 infections caused by Gram-negative bacilli were treated with temocillin 2g twice daily by the direct intravenous route. The patients (17 men and 10 women) were aged from 35 to 93 years (mean 65.7 years) and 22 had severe underlying diseases. In addition, 10 of the patients were admitted to the intensive care unit following surgery; 6 had acute renal insufficiency, 5 had acute respiratory insufficiency, and 12 were suffering from infectious shock. The infections included septicaemia (19), urinary tract infection (10), respiratory tract infection (4) and biliary tract infection (4). The most frequent bacterial isolate was Escherichia coli (14), followed by Enterobacter cloacae (5), Proteus spp. (5) and Klebsiella pneumoniae (4). The initial pathogens were eliminated in 34/40 infections (85%) and the corresponding clinical cure rate was 60%, with a further 27.5% of patients being improved. In the septicaemic patients, 17/19 pathogens were eradicated from the blood, while clinically, 12 patients were cured and 5 were improved. Eight of the 10 urinary tract pathogens were eliminated, with 6 patients being clinically cured and a further 3 being improved. All of the initial pathogens in both biliary tract and respiratory tract infections were eradicated, accompanied by clinical success in 3 and 2 patients, respectively; the remaining patients were improved. Superinfection with streptococcus group D, Pseudomonas aeruginosa and Staphylococcus aureus was seen in 3 patients. The emergence of resistance to temocillin occurred in an isolate of E. coli, and also possibly in an isolate of K. pneumoniae. No adverse reactions nor abnormal laboratory values related to temocillin administration were observed and, although 7 patients died, none of the deaths were attributable to uncontrolled Gram-negative infection.

BioHackathon 2015: Semantics of data for life sciences and reproducible research

We report on the activities of the 2015 edition of the BioHackathon, an annual event that brings together researchers and developers from around the world to develop tools and technologies that promote the reusability of biological data. We discuss issues surrounding the representation, publication, integration, mining and reuse of biological data and metadata across a wide range of biomedical data types of relevance for the life sciences, including chemistry, genotypes and phenotypes, orthology and phylogeny, proteomics, genomics, glycomics, and metabolomics. We describe our progress to address ongoing challenges to the reusability and reproducibility of research results, and identify outstanding issues that continue to impede the progress of bioinformatics research. We share our perspective on the state of the art, continued challenges, and goals for future research and development for the life sciences Semantic Web.

[Health Protection in the Workplace: Special Commission of the Swiss Society for Occupational Medicine, Occupational Hygiene and Occupational Safety]

Fridolin Schuler (1832-1903), physician in Glarus, laid the foundations of the Swiss legislation for the protection of the working population. The law for illness and accident insurance followed in 1911, it was complemented with regulations concerning the protection from occupational diseases. Of great practical importance were coordinated efforts of physicians, technologists, hygienists and safety engineers, who founded in 1956 the "Studiengruppe für Gesundheitsschutz in Industrie und Gewerbe". In 1973 they joined with the "Groupement romand" in the "Swiss Society for occupational medicine, occupational hygiene and occupational safety" (AAA). In 1964 the Association of Swiss occupational physicians has been founded. In order to strengthen the promotion of occupational health in Switzerland a special commission on occupational medicine was constituted in 1980 within the AAA. Several subcommissions are presently working on a steadily increasing number of problems in the field of occupational health.

[Disseminated intravascular coagulations]

Disseminated intravascular coagulation (DIC) syndromes can be defined as the formation of fibrin deposits within the microcirculation, occurring in definite clinical situations. Their biological counterpart is a consumption coagulopathy. The clinical profiles of DIC have been well known for decades, are multiform and range from latency to overwhelming haemorrhagic diatheses, including also characteristic but rare situations, such as purpura fulminans, acral cyanosis and pictures resembling thrombotic thrombocytopenic purpura or haemolytic-uraemic syndrome. Biological tests of DIC show a consumption coagulopathy, displayed on the standard haemostasis sheet; along with signs of paracoagulation and/or of secondary fibrinolysis (FDP). New tests have recently been introduced: D-dimers are specific and sensible; Antithrombin-III, protein C and alpha 2-antiplasmin also can sometimes be useful. The knowledge of the pathophysiology of DIC has made advances with passing years. Fibrin deposits may be non-occlusive, and indeed they are swiftly removed by a secondary fibrinolysis. Except in very rare situations, such as those leading to a cortical renal necrosis, and perhaps in some ARDS, there is little evidence relating DIC to organ failure syndromes. Moreover, there is no clear relationship between the severity of the consumption coagulopathy and the prognosis. For instance, the mortality is much lower in abruptio placentae, where the coagulopathy is very severe, than in septic shock, where it is usually moderate. In septic shock, the disorders of haemostasis were related initially to a platelet activation, then to an activation of the contact system (releasing kinins and triggering complement cascade), and nowadays to the activation of the extrinsic coagulation system. The treatment of DIC is mainly the treatment of its cause. Indications for heparin therapy should be strictly limited to a few exceptional circumstances. When haemorrhagic diathesis threatens, FPC and/or platelet transfusion may be indicated. Aprotinin can be useful in rare cases of overwhelming secondary fibrinolysis. Trials with antithrombin-III or C1-esterase inhibitors are in progress.

[Alcoholic ketoacidosis. One case (author's transl)]

Severe ketoacidosis sometimes develops in chronic alcoholics after increased alcohol intake associated with dietary restriction. This particular case was unusual from two standpoints: a considerable, prolonged and unexplained increase in serum free fatty acid, and discordance between the degree of ketonaemia and an abundant liver glycogen load.