Performance evaluation of canine-associated Bacteroidales assays in a multi-laboratory comparison study

The contribution of fecal pollution from dogs in urbanized areas can be significant and is an often underestimated problem. Microbial source tracking methods (MST) utilizing quantitative PCR of dog-associated gene sequences encoding 16S rRNA of Bacteroidales are a useful tool to estimate these contributions. However, data about the performance of available assays are scarce. The results of a multi-laboratory study testing two assays for the determination of dog-associated Bacteroidales (DogBact and BacCan-UCD) on 64 single and mixed fecal source samples created from pooled fecal samples collected in California are presented here. Standardization of qPCR data treatment lowered inter-laboratory variability of sensitivity and specificity results. Both assays exhibited 100% sensitivity. Normalization methods are presented that eliminated random and confirmed non-target responses. The combination of standardized qPCR data treatment, use of normalization via a non-target specific Bacteroidales assay (GenBac3), and application of threshold criteria improved the calculated specificity significantly for both assays. Such measures would reasonably improve MST data interpretation not only for canine-associated assays, but for all qPCR assays used in identifying and monitoring fecal pollution in the environment.     

New dendrimer-peptide host-guest complexes: towards dendrimers as peptide carriers

Adamantyl urea and adamantyl thiourea modified poly(propylene imine) dendrimers act as hosts for N-terminal tert-butoxycarbonyl (Boc)-protected peptides and form chloroform-soluble complexes. Investigations with NMR spectroscopy show that the peptide is bound to the dendrimer by ionic interactions between the dendrimer outer shell tertiary amines and the C-terminal carboxylic acid of the peptide, and also through host-urea to peptide-amide hydrogen bonding. The hydrogen-bonding nature of the peptide-dendrimer interactions was further confirmed by using Fourier transform IR spectroscopy, for which the NH- and CO-stretch signals of the peptide amide moieties shift towards lower wavenumbers upon complexation with the dendrimer. Spatial analysis of the complexes with NOESY spectroscopy generally shows close proximity of the N-terminal Boc group of the peptide to the peripheral adamantyl groups on the dendrimer host. The influence of side-chain motif on interactions with the host is analyzed by using seven different N-Boc-protected tripeptides as guests for the dendrimer. Downfield shifts of up to 1.3 ppm were observed for the guest amide NH-proton signals. These shifts decreased with increasing 'bulkiness' of the amino acid side chains. Despite this, the dendrimer was capable of making multiple peptide-dendrimer complexes when presented with a library of seven peptides. The different peptides were all present in the host, which did not show specific preferences, and could be released under mild acidic conditions. These results show the general nature of the peptide-dendrimer interactions in the formation of either single- or multiple-peptide-dendrimer complexes.     

Hepatobiliary and intestinal clearance of amphiphilic cationic drugs in mice in which both mdr1a and mdr1b genes have been disrupted

The triumph of antibiotics over bacterial pathogens that has occurred in the latter half of this century looks increasingly threatened as we approach the new millennium. Increasing resistance in important pathogens such as Mycobacterium tuberculosis, Shigella, and Streptococcus pneumoniae threatens the lives of millions. The increasing problems with drug resistance in (C. diphtheriae, Salmonella typhi and the pneumococcus in Vietnam are presented as examples of the challenge confronting tropical countries.     

Addisonian crisis provoked by levothyroxine substitution therapy

A women aged 36 with a positive family anamnesis for autoimmune endocrine diseases and a history of thyroid diseases, developed major complaints of general malaise, orthostatic hypotension and loss of appetite after the start of a treatment with levothyroxin because of (sub)clinical hypothyroidism. She was found to suffer from primary adrenocortical insufficiency masked by excessive use of liquorice and a lowered metabolism, but which via the suppletion with thyroid hormone had led to an addisonian crisis.     

Single Crystals of HgBa2Can−1CunO2n+2+δ (n=1−5) and Layers of HgBa2CuO4+δ Grown at Gas Pressure 10 kbar

Single crystals of Hg-12(n?l) have been grown using high-pressure gas-technique. Due to the high density of Ar gas at 10 kbar the evaporation of Hg is strongly suppresed. An influence of structure defects on magnetic properties will be discussed. Superconducting parameters λ _ab ,ξ _ab and γ have been studied using torque magnetometry. Layers of Hg-1201 compound have been grown from flux.     

Inflammation of the tail in swine. Slaughter-house findings during 1972, 1973, and 1974 (author's transl)

In the Public Salughter-House of Utrecht, a percentage increase in the number of pigs with inflammation of the tail, which had or had not healed, was observed during the period from 1972 to 1974 inclusive. The most common secondary symptoms of inflammation consisted in embolic pneumonia, osteomyelitis of the vertebrae and abscess formation in other parts of the body, particularly the semimebranosus muscles. Osteomyelitis was found to be the most common complication in pigs in which the inflammation of the tail had healed, whereas this usually consisted in embolic pneumonia in those cases in which the inflammation of the tail had not healed. The bacteriological examination carried out in accordance with the Meat Inspection Regulations was positive in 21.7 per cent, 13.5 per cent of the cases respectively in 1972, 1973 and 1974. Micro-organisms were isolated much more frequently from the kidney than they were from the spleen and meat. There was no relationship between the presence of inflammation of the tail and climatological conditions during the fattening period. The losses at slaughter from inflammation of the tail in the Netherlands are estimated at 3-4 million guilders per annum.     

Flexible active-matrix displays and shift registers based on solution-processed organic transistors

At present, flexible displays are an important focus of research. Further development of large, flexible displays requires a cost-effective manufacturing process for the active-matrix backplane, which contains one transistor per pixel. One way to further reduce costs is to integrate (part of) the display drive circuitry, such as row shift registers, directly on the display substrate. Here, we demonstrate flexible active-matrix monochrome electrophoretic displays based on solution-processed organic transistors on 25-microm-thick polyimide substrates. The displays can be bent to a radius of 1 cm without significant loss in performance. Using the same process flow we prepared row shift registers. With 1,888 transistors, these are the largest organic integrated circuits reported to date. More importantly, the operating frequency of 5 kHz is sufficiently high to allow integration with the display operating at video speed. This work therefore represents a major step towards 'system-on-plastic'.     

Roscovitine and other purines as kinase inhibitors. From starfish oocytes to clinical trials

This article reviews the steps that have led us from very fundamental research on the cell division cycle, investigated with the starfish oocyte model, to the identification of drugs now being evaluated against cancer in the clinic. Among protein kinases activated during entry in M phase, the cyclin-dependent kinase CDK1/cyclin B was initially identified as a universal M-phase promoting factor. It was then used as a screening target to identify pharmacological inhibitors. The first inhibitors to be discovered were 6-dimethylaminopurine and isopentenyladenine, from which more potent and selective inhibitors were optimized (olomoucine, roscovitine, and purvalanols). All were cocrystallized with CDK2 and found to localize in the ATP-binding pocket of the kinase. Their selectivity and cellular effects have been thoroughly investigated. Following encouraging results obtained in preclinical tests and favorable pharmacological properties, one of these purines, roscovitine (CYC202), is now entering phase II clinical trials against cancers and phase I clinical tests against glomerulonephritis. CDK inhibitors are also being evaluated, at the preclinical level, for therapeutic use against neurodegenerative diseases, cardiovascular disorders, viral infections, and parasitic protozoa. This initially unexpected scope of potential applications and the large number and chemical diversity of pharmacological inhibitors of CDKs now available constitute a very encouraging stimulus to pursue the search for optimization and characterization of protein kinase inhibitors, from which we expect numerous therapeutic applications.     

High-speed path-length scanning with a multiple-pass cavity delay line

Techniques for high-speed delay scanning are important for low-coherence interferometry, optical coherence tomography, pump probe measurements, and other applications. We demonstrate a novel scanning delay line using a multiple-pass cavity. Differential delays are accumulated with each pass so that millimeter delays can be generated with tens of micrometer mirror displacements. With special design criteria, misalignment sensitivity can be dramatically reduced. The system is demonstrated to scan 6 m/s at 2-kHz repetition rates. Real-time optical coherence tomography imaging with 500 pixel images at four frames/s is performed. Using a Cr:forsterite laser source, we obtained axial image resolutions of 6 microm with 92-dB sensitivity.