Bayesian estimation of a random effects heteroscedastic probit model

Summary Bayesian analysis is given of a random effects binary probit model that allows for heteroscedasticity. Real and simulated examples illustrate the approach and show that ignoring heteroscedasticity when it exists may lead to biased estimates and poor prediction. The computation is carried out by an efficient Markov chain Monte Carlo sampling scheme that generates the parameters in blocks. We use the Bayes factor, cross‐validation of the predictive density, the deviance information criterion and Receiver Operating Characteristic (ROC) curves for model comparison.     

CGP 6809 — A new nitrosoureido-sugar derivative with activity in human tumor xenografts

Summary CGP 6809 [ethyl-6-deoxy-3,5-di-O-methyl-6-(3-methyl-3-nitrosoureido)--d-glucofuranoside] is a new methylnitrosoureido-sugar derivative that has been shown to be active against a broad spectrum of transplantable tumours in mice and rats [14]. We investigated the anti-tumour effect of CGP 6809 in ten selected, human tumour xenograft lines growing s. c. in nude mice. The p. o. administration of 125 mg/kg per day for 10–15 days was less toxic (lethality 12% in tumour-bearing nude mice) than the i. p. injection of 62.5 mg/kg per day (lethality 22%). The anti-tumour effect was similar for both application routes; two large bowel cancers responded to treatment with CGP 6809, rectal cancer CXF 158 showed a remission, and the rapidly growing, undifferentiated colonic cancer CXF 280 exhibited a transient no-change. Furthermore, remissions were observed in the epidermoid lung cancer LXF 322 and in thyroid cancer 117. Tumour progression was found in another epidermoid lung cancer and in three stomach cancers, one melanoma, and one soft tissure sarcoma. CGP 6809 is a promising new agent for clinical trials, especially for large bowel and epidermoid lung cancer.Supported in part by grant PTB 8467 from the Bundesminister für Forschung und Technologie, Bonn, FRG     

Purification and immunobiochemical characterization of folding variants of the recombinant major wasp allergen Ves v 5 (antigen 5)

Background: Antigen 5 is one of three major allergens in wasp venoms, but unlike phospholipase A(1) and hyaluronidase, both of which are enzymes, its biological function is unknown. The cDNA coding for this allergen has been isolated and used for recombinant expression. Thorough analysis of the expression product is essential in order to evaluate the usefulness for in vivo or in vitro application. Objective: In this study, folding variants of the recombinant major allergen Ves v 5 from Vespula vulgaris were immunologically and biochemically investigated in order to determine their possible applicability for diagnostic or therapeutic purposes. Method: The cDNA encoding Ves v 5 was cloned into the expression vector pSE420 which generates recombinant products lacking a tag sequence. After expression, inclusion bodies were purified, subsequently denatured and dialyzed against different solutions. The structural properties of soluble proteins were analyzed by size exclusion chromatography, non-reducing SDS-PAGE, native PAGE, N-terminal sequencing, proteolytic digestion and ion exchange chromatography. Immunological investigations were performed by using different monoclonal antibodies (mAbs) specific for Ves v 5 and IgE from patients allergic to wasp venom allergens. Results: After dialysis, soluble monomeric recombinant Ves v 5 was more than 95% pure in each case. Using different dialysis solutions, clearly distinguishable folding variants were obtained. In one case, the recombinant allergen was comparable with the natural counterpart in respect of migration in non-reducing SDS-PAGE, native PAGE and IgE reactivity. This variant reacted with two different Ves v 5-specific mAbs and produced a stable fragment after proteolytic digestion. Elution from a cation exchange chromatography column was achieved with 320 mM NaCl. In two other cases, folding variants exhibited a different migration behavior in SDS-PAGE and native PAGE compared with the natural allergen. Also, the mAb 1E11 recognized none of these variants since it presumably detected a conformational epitope. Moreover, the IgE reactivity was clearly reduced and proteolytic digestion effected almost complete degradation. These variants eluted from the cation exchange column with 400 mM NaCl. Conclusion: Defined folding strategies resulted in both soluble misfolded variants with reduced IgE reactivity, potentially suitable for immunotherapy, and natural-like folded variants for diagnosis.     

Rapid method for arrayed investigation of IgE-reactivity profiles using natural and recombinant allergens

BACKGROUND: The availability of increasing numbers of purified natural and recombinant allergens offer the possibility for component-resolved characterization of IgE binding. To make use of this potential, fast and simple methods with high capacity have to be developed. METHODS: A laboratory multiscreen device was used in an innovative two-dimensional approach. In the first step, natural and recombinant allergens were immobilized onto the membrane using the sample chambers as application mask and, after blocking and rotating the membrane through 90 degrees, the same device was used to apply and incubate sera of allergic patients. Enzyme-linked immunoassay (ELISA) quantification of specific IgE was performed for purposes of comparison. RESULTS: Proteins were most efficiently bound onto nitrocellulose in 20 mM sodium hydroxide (NaOH). Up to 45 proteins or extracts could be investigated with a maximum of 45 sera in a single application, resulting in a resolution of 2,025 spots on one membrane with a size comparable to a standard Western blot. A high correlation for IgE-binding between natural and recombinant allergens was observed. Development of the membrane resulted in very evenly distributed square patterns. The results corresponded with the conventional ELISA measurements of specific IgE. CONCLUSIONS: The innovative usage of a standard incubation device for both application of proteins as well as screening of sera provides a simple high throughput method for the characterization of IgE binding to allergens. The results are important for component resolved diagnosis of allergy by means of fast monitoring of IgE- and IgG-reactivity spectra. Recombinant allergens may be used as targets for these purposes.     

SARS-CoV-2-Seroprävalenz bei Kindern und Jugendlichen in Deutschland – ein Überblick

Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz - SARS-CoV-2-Antikörperstudien ergänzen und erweitern die Erkenntnisse aus der Meldestatistik laborbestätigter...     

Chinikomycins A and B: isolation, structure elucidation, and biological activity of novel antibiotics from a marine Streptomyces sp. isolate M045

In our screening of marine Streptomycetes for bioactive principles, two novel antitumor antibiotics designated as chinikomycins A (2a) and B (2b) were isolated together with manumycin A (1), and their structures were elucidated by a detailed interpretation of their spectra. Chinikomycins A (2a) and B (2b) are chlorine-containing aromatized manumycin derivatives of the type 64-pABA-2 with an unusual para orientation of the side chains. They exhibited antitumor activity against different human cancer cell lines, but were inactive in antiviral, antimicrobial, and phytotoxicity tests.     

Cytotoxic bastadin 24 from the Australian sponge Ianthella quadrangulata

A new cytotoxic bastadin, bastadin 24 ( 1), and the previously reported bastadins 4, 5, 6, 7, 12, 13, and 21 ( 2- 8) were isolated from a polar extract of the Australian marine sponge Ianthella quadrangulata. The planar structure of bastadin 24 ( 1) was elucidated as the 25-hydroxy derivative of bastadin 6 ( 4) by employing spectroscopic techniques (NMR, MS, UV, and IR). All isolated bastadins were evaluated for their cytotoxicity toward a panel of 36 human tumor cell lines and were found to be moderately cytotoxic. Bastadin 24 ( 1) exhibited selective cytotoxic activity toward five of the 36 investigated tumor cell lines. Bastadins 7 ( 5) and 12 ( 6) significantly inhibited the serum + hEGF-induced (human epithelial growth factor) tubular formation of human umbilical vein endothelial cells (HUVEC) at a concentration of 1 mug/mL.     

Neoplastic human embryonic stem cells as a model of radiation resistance of human cancer stem cells

Studies have implicated that a small sub-population of cells within a tumour, termed cancer stem cells (CSCs), have an enhanced capacity for tumour formation in multiple cancers and may be responsible for recurrence of the disease after treatment, including radiation. Although comparisons have been made between CSCs and bulk-tumour, the more important comparison with respect to therapy is between tumour-sustaining CSC versus normal stem cells that maintain the healthy tissue. However, the absence of normal known counterparts for many CSCs has made it difficult to compare the radiation responses of CSCs with the normal stem cells required for post-radiotherapy tissue regeneration and the maintenance of tissue homeostasis. Here we demonstrate that transformed human embryonic stem cells (t-hESCs), showing features of neoplastic progression produce tumours resistant to radiation relative to their normal counterpart upon injection into immune compromised mice. We reveal that t-hESCs have a reduced capacity for radiation induced cell death via apoptosis and exhibit altered cell cycle arrest relative to hESCs in vitro. t-hESCs have an increased expression of BclXL in comparison to their normal counterparts and re-sensitization of t-hESCs to radiation upon addition of BH3-only mimetic ABT737, suggesting that overexpression of BclXL underpins t-hESC radiation insensitivity. Using this novel discovery platform to investigate radiation resistance in human CSCs, our study indicates that chemotherapy targeting Bcl2-family members may prove to be an adjuvant to radiotherapy capable of targeting CSCs.     

Recommended Immunological Strategies to Screen for Botulinum Neurotoxin-Containing Samples

Botulinum neurotoxins (BoNTs) cause the life-threatening neurological illness botulism in humans and animals and are divided into seven serotypes (BoNT/A–G), of which serotypes A, B, E, and F cause the disease in humans. BoNTs are classified as “category A” bioterrorism threat agents and are relevant in the context of the Biological Weapons Convention. An international proficiency test (PT) was conducted to evaluate detection, quantification and discrimination capabilities of 23 expert laboratories from the health, food and security areas. Here we describe three immunological strategies that proved to be successful for the detection and quantification of BoNT/A, B, and E considering the restricted sample volume (1 mL) distributed. To analyze the samples qualitatively and quantitatively, the first strategy was based on sensitive immunoenzymatic and immunochromatographic assays for fast qualitative and quantitative analyses. In the second approach, a bead-based suspension array was used for screening followed by conventional ELISA for quantification. In the third approach, an ELISA plate format assay was used for serotype specific immunodetection of BoNT-cleaved substrates, detecting the activity of the light chain, rather than the toxin protein. The results provide guidance for further steps in quality assurance and highlight problems to address in the future.