Persistent electrical coupling and locomotory dysfunction in the zebrafish mutant shocked

On initial formation of neuromuscular junctions, slow synaptic signals interact through an electrically coupled network of muscle cells. After the developmental onset of muscle excitability and the transition to fast synaptic responses, electrical coupling diminishes. No studies have revealed the functional importance of the electrical coupling or its precisely timed loss during development. In the mutant zebrafish shocked (sho) electrical coupling between fast muscle cells persists beyond the time that it would normally disappear in wild-type fish. Recordings from sho indicate that muscle depolarization in response to motor neuron stimulation remains slow due to the low-pass filter characteristics of the coupled network of muscle cells. Our findings suggest that the resultant prolonged muscle depolarizations contribute to the premature termination of swimming in sho and the delayed acquisition of the normally rapid touch-triggered movements. Thus the benefits of gap junctions during early synapse development likely become a liability if not inactivated by the time that muscle would normally achieve fast autonomous function.     

Recombinant Helicobacter bilis Protein P167 for Mouse Serodiagnosis in a Multiplex Microbead Assay

Infection of mice with Helicobacter bilis is widespread in research and commercial mouse colonies. Therefore, sensitive, specific, and high-throughput assays are needed for rapid and accurate testing of mice in large numbers. This report describes a novel multiplex assay, based on fluorescent microbeads, for serodetection of H. bilis infection. The assay requires only a few microliters of serum to perform and is amenable to a high-throughput format. Individual microbead sets were conjugated to purified, H. bilis-specific, recombinant proteins P167C and P167D and bacterial membrane extracts from H. bilis and Helicobacter hepaticus. For detecting H. bilis infection in the microbead multiplex assay, P167C and P167D provided significantly higher sensitivities (94 and 100%, respectively) and specificities (100 and 95%, respectively) than membrane extract (78% sensitivity and 65% specificity). Microbead multiplex assay results were validated by enzyme-linked immunosorbent assay. Purified recombinant proteins showed low batch-to-batch variation; this feature allows for ease of quality control, assay robustness, and affordability. Thus, recombinant antigens are highly suitable in the multiplex microbead assay format for serodetection of H. bilis infection.     

Plasmodium falciparum merozoite surface protein 8 is a ring-stage membrane protein that localizes to the parasitophorous vacuole of infected erythrocytes

To date, the following seven glycosylphosphatidylinositol (GPI)-anchored merozoite antigens have been described in Plasmodium falciparum: merozoite-associated surface protein 1 (MSP-1), MSP-2, MSP-4, MSP-5, MSP-8, MSP-10, and the rhoptry-associated membrane antigen. Of these, MSP-1, MSP-8, and MSP-10 possess a double epidermal growth factor (EGF)-like domain at the C terminus, and these modules are considered potential targets of protective immunity. In this study, we found that surprisingly, P. falciparum MSP-8 is transcribed and translated in the ring stage and is absent from the surface of merozoites. MSP-8 is the only GPI-anchored protein known to be expressed at this time. It is synthesized as a mature 80-kDa protein which is rapidly processed to a C-terminal 17-kDa species that contains the double EGF module. As determined by a combination of immunofluorescence and membrane purification approaches, it appears likely that MSP-8 initially localizes to the parasite plasma membrane in the ring stage. Although the C-terminal 17-kDa fragment is present in more mature stages, at these times it is found in the food vacuole. We successfully disrupted the MSP-8 gene in P. falciparum, a process that validated the specificity of the antibodies used in this study and also demonstrated that MSP-8 does not play a role essential to maintenance of the erythrocyte cycle. This finding, together with the observation that MSP-8 is exclusively intracellular, casts doubt over the viability of this antigen as a vaccine. However, it is still possible that MSP-8 is involved in an early parasitophorous vacuole function that is significant for pathogenesis in the human host.     

Targeting accuracy of an image guided gating system for stereotactic body radiotherapy

Recently, a commercial system capable of x-ray image guided patient positioning and respiratory gated delivery has become available. Here we describe the operational principles of this system and investigate its geometric targeting accuracy under controlled conditions. The system tracks breathing via infrared (IR) detection of reflective markers located on the patient's abdomen. Localization kilovoltage (kV) x-rays are triggered from within the gated delivery window portion of the breathing trace and after positioning, the tumour will cross the linac isocentre during gated delivery. We tested geometric accuracy of this system by localizing and delivering gated fields to a moving phantom. Effects of phantom speed, gating window location, timing errors and phantom rotations on positioning and gating accuracy were investigated. The system delivered gated fields to both a moving and static phantom with equal accuracy. The position of the gating window affects accuracy only to the extent that an asymmetric breathing motion could affect dose distribution within its boundaries. Positioning errors were found to be less then 0.5 +/- 0.2 mm for phantom rotations up to 5 degrees. We found and corrected a synchronization error caused by a faulty x-ray duration setting and detected a 60 +/- 20 ms time delay in our linear accelerator.     

Porphyromonas gingivalis RgpA and Kgp proteinases and adhesins are C terminally processed by the carboxypeptidase CPG70

Porphyromonas gingivalis is a bacterial pathogen that produces the polyproteins RgpA and Kgp, which are proteolytically processed into proteinases and adhesins. We have demonstrated that the RgpA and Kgp proteinases and adhesins are C terminally processed by carboxypeptidase CPG70 by sequencing C-terminal peptides from both the wild type and an isogenic CPG70 mutant, using ion trap mass spectrometry.     

In vitro performance of the novel coronary sinus AutoRetroPerfusion Cannula

Myocardial salvage through coronary sinus intervention has been documented. The AutoRetroPerfusion Cannula is a novel device that is able to perfuse the coronary bed retrogradely through the coronary sinus with arterial blood generated from a peripheral artery with no need for a pump. The cannula consists of a distal end that, once secured in the coronary sinus, opens an umbrella-like membrane to create pressure in the coronary sinus, and at the same time has small channels directed backwards to the right atrium to provide pressure relief. The cannula is introduced from the axillary vein under local anesthesia and the proximal end, which consists of a graft, is anastomosed to the axillary artery to start autoperfusion once the distal end is secured in the coronary sinus and the occluding membrane is open. The AutoRetroPerfusion Cannula was tested in the in vitro mock loop under 50-120 mm Hg of proximal pressure and 50, 100, and 150 ml/min of total flow in the cannula. We were able to achieve the nominal design point of 40-80 mm Hg of distal pressure and 50-150 ml/min of distal flow by adjusting the number, diameter, and length of the small backwards channels.     

Influence of small additions of hexamethylphosphoric triamide on the kinetics of polymerization of styrene in THF

Unsaturated polyamides from methyl-fumaric (2-methyl-fumaric and 2.3-dimethyl-fumaric) acid dichlorides and diamines, i.e. 1.6-hexamethylenediamine, 1.10-decamethylenediamine, m-xylylenediamine, piperazine and trans-2.5-dimethylpiperazine were synthesized by low-temperature polycondensation. The polymer structures and properties were investigated by IR, X-ray, NMR, DSC, and TGA analyses. All polyamides were found to be soluble in several volatile organic solvents: furthermore – unlike polyamides derived from unsubstituted fumaric acid – polyamides from substituted fumaric acid derived from primary diamines showed melting or softening points.     

Antagonistic effects upon cutaneous circulation of muscular exercise and exposure to a high ambient temperature

Measurements were made in man of heart rate (Fc), arterial blood pressure (Pa), cutaneous blood flow (Z) (by plethysmography of the hand) as well as variation sin venous volume (deltaV) in the course of muscular exercise of 70 Watts intensity corresponding from 48% to 60% of the maximal oxygen consumtion of the subjects. These exercises were carried out at ambient temperatures of 22 degrees and 29 degrees C. for 8 min. In every case, an initial lowering of the Q and deltaV followed by a progressive climb was found. The average maximal reduction in output was virtually identical at 22 degrees and 29 degrees C (4.10 +/- 2.05 and 4.00 +/- 2.31 ml/min. 100 cm3). But the average maximal fall in volume turned out to be less at 29 degrees C (0.30 +/- 0.40 ml/100 cm3) than at 22 degrees C (0.60 +/- 0.60 ml/100 cm3). The resistive sector of cutaneous circulation conserves the same vasomotor capacities at the two ambient temperatures studied; the cutaneous capacitive sector shows lower reactivity at the higher ambient temperature. This would suggest that diminished venous return may be partially responsible for poor tolerance to exercise in warm climates.     

A histochemical study of the inclusion bodies in the small intestine of the developing rat

Summary The morphology and histochemstry of the epithelium in the small intestine was studied in the fetal and suckling rat. Large supranuclear inclusion bodies in the ileum of the suckling animal demonstrated positive reactions for the following components and enzymes: lipofuscins; amino and SH groups; 1–2 glycols (amylase-resistant PAS-positive reaction); alkaline phosphatase; acid phosphatase; and non-specific esterase. These structures were unstained with Alcian blue and demonstrated no leucine aminopeptidase activity.Small PAS-positive droplets and unstained vacuoles formed in the supranuclear cytoplasm during terminal gestation. During the first 24–48 hours postpartum, the droplets enlarged rapidly and formed the large supranuclear inclusions. However, high levels of enzyme activity did not occur in the large inclusions until 2–4 days after birth. This phenomenon may-be related to the levels of production and/or accumulation of enzymes within the columnar cell.