A laboratory study of bacteria-facilitated cadmium transport in alluvial gravel aquifer media.

Colloids, including bacteria, can dramatically accelerate the transport of heavy metals in ground water. Batch and column experiments were conducted to investigate adsorption of cadmium (Cd) onto Bacillus subtilis spores or Escherichia coli vegetative cells and Cd transport in alluvial gravel aquifer media in the presence of these bacteria. Results of the batch experiments showed that adsorption of Cd onto the bacteria was (i) positively related to solution pH, bacterial concentration, and negative surface charge, but inversely related to Cd concentration and (ii) a rate-limited nonlinear process, but adsorption onto E.

First results from the Cryogenic Dark Matter Search in the Soudan Underground Laboratory.

We report the first results from a search for weakly interacting massive particles (WIMPs) in the Cryogenic Dark Matter Search experiment at the Soudan Underground Laboratory. Four Ge and two Si detectors were operated for 52.6 live days, providing 19.

Cloning and functional expression of invertebrate connexins from Halocynthia pyriformis.

Unlike many other ion channels, unrelated gene families encode gap junctions in different animal phyla. Connexin and pannexin genes are found in deuterostomes, while protostomal species use innexin genes. Connexins are often described as vertebrate genes, despite the existence of invertebrate deuterostomes.

Confirming the species-sensitivity distribution concept for endosulfan using laboratory, mesocosm, and field data.

In Australia, water-quality trigger values for toxicants are derived using protective concentration values based on species-sensitivity distribution (SSD) curves. SSD curves are generally derived from laboratory data with an emphasis on using local or site-specific data. In this study, Australian and non-Australian laboratory-species based SSD curves were compared and the concept of species protection confirmed by comparison of laboratory-based SSD curves with local mesocosm experiments and field monitoring data.

Aquatic risk assessment of a realistic exposure to pesticides used in bulb crops: a microcosm study.

The fungicide fluazinam, the insecticide lambda-cyhalothrin, and the herbicides asulam and metamitron were applied to indoor freshwater microcosms (water volume approximately 0.6 m3). The treatment regime was based on a realistic application scenario in tulip cultivation.

Recreating the biological pacemaker.

In recent years, several groups have reported a variety of strategies for developing biological pacemakers whose ultimate function would be to supplement/replace electronic pacemakers. Strategies have included gene therapy using naked plasmids or viral vectors and cell therapy for which both adult human mesenchymal stem cells (hMSCs) and human embryonic stem cells have been employed. This article reviews the various approaches and summarizes our own research in which the pacemaker gene, HCN2, is administered via viral vector or in an hMSC platform to produce pacemaker function in the intact canine heart.

Genes, stem cells and biological pacemakers.

The advent of gene therapy and cell therapy has led to reconsideration of standard therapies for cardiac disease. One such area of reconsideration is that of the cardiac pacemaker, which has been the mainstay of treatment for high-degree heart block and sinoatrial node dysfunction. Over the past five years, gene therapy has been used to explore the overexpression of beta(2)-adrenergic receptors, the down-regulation of inward rectifier current, and the overexpression of pacemaker current as potential sources of biological pacemakers.

Effect of oxygen tension on adult articular chondrocytes in microcarrier bioreactor culture.

Tissue-engineering approaches for cartilage repair hold promise for the treatment of cartilage defects. Various methods to prevent or reduce dedifferentiation during chondrocyte expansion are currently under investigation. In the present study we evaluated the effect of oxygen on chondrocyte proliferation, as oxygen has received increased attention as a possible regulator of chondrocyte differentiation and its effect during expansion is uncertain.

Biophysical characterization of zebrafish connexin35 hemichannels.

A subset of connexins can form unopposed hemichannels in expression systems, providing an opportunity for comparison of hemichannel gating properties with those of intact gap junction channels. Zebrafish connexin35 (Cx35) is a member of the Cx35/Cx36 subgroup of connexins highly expressed in the retina and brain. In the present study, we have shown that Cx35 expression in Xenopus oocytes and N2A cells produced large outward whole cell currents on cell depolarization.

Progressive familial heart block type II (PFHBII): a clinical profile from 1977 to 2003.

An evaluation of a 38-year-old Caucasian woman, who was referred to Tygerberg Hospital (Western Cape Province, RSA) with Wenckebach second-degree or possibly complete atrioventricular (AV) block that had progressed from first-degree AV block, identified a family history of the cardiac conduction system disorder progressive familial heart block type II (PFHBII). This prompted a retrospective clinical review of the subjects described in the original study, as well as additional family members who had not been examined in the original study. Progression of clinical features was observed, but more importantly, PFHBII was clinically redefined as an AV nodal disorder, which may progress to dilated cardiomyopathy (DCM).

Altered gating properties of functional Cx26 mutants associated with recessive non-syndromic hearing loss.

Connexins (Cx) form gap junctions that allow the exchange of small metabolites and ions. In the inner ear, Cx26 is the major gap junction protein and mutations in the Cx26-encoding gene, GJB2, are the most frequent cause of autosomal recessive non-syndromic hearing loss (DFNB1). We have functionally analyzed five Cx26 mutations associated with DFNB1, comprising the following single amino-acid substitutions: T8M, R143W, V153I, N206S and L214P.

Comparison of laboratory single species and field population-level effects of the pyrethroid insecticide lambda-cyhalothrin on freshwater invertebrates.

The toxicity of the pyrethroid insecticide lambda-cyhalothrin to freshwater invertebrates has been investigated using data from short-term laboratory toxicity tests and in situ bioassays and population-level effects in field microcosms. In laboratory tests, patterns of toxicity were consistent with previous data on pyrethroids. The midge Chaoborus obscuripes was most sensitive (48- and 96-h EC50 = 2.

Connexin43 and connexin26 form gap junctions, but not heteromeric channels in co-expressing cells.

Many cells contain two (or more) gap junction proteins that are able to oligomerize with each other to form heteromeric gap junction channels and influence the properties of intercellular communication. Cx26 and Cx43 are found together in a number of cell types, but previous data have suggested that they might not form heteromeric connexons. We studied the possible interactions of these connexins by co-expression in three different cell lines.

Left cardiac sympathetic denervation in the management of high-risk patients affected by the long-QT syndrome.

Background: The management of long-QT syndrome (LQTS) patients who continue to have cardiac events (CEs) despite beta-blockers is complex. We assessed the long-term efficacy of left cardiac sympathetic denervation (LCSD) in a group of high-risk patients.

Methods And Results: We identified 147 LQTS patients who underwent LCSD.

The effects of a pesticide mixture on aquatic ecosystems differing in trophic status: responses of the macrophyte Myriophyllum spicatum and the periphytic algal community.

The effects of a pesticide mixture (asulam, fluazinam, lambda-cyhalothrin, and metamitron) on aquatic ecosystems were investigated in 20 outdoor aquatic microcosms. Ten of the microcosms simulated mesotrophic aquatic ecosystems dominated by submerged macrophytes (Elodea). The others simulated eutrophic ecosystems with a high Lemna surface coverage (Lemna).

Selective permeability of gap junction channels.

Gap junctions mediate the transfer of small cytoplasmic molecules between adjacent cells. A family of gap junction proteins exist that form channels with unique properties, and differ in their ability to mediate the transfer of specific molecules. Mutations in a number of individual gap junction proteins, called connexins, cause specific human diseases.

Human mesenchymal stem cells as a gene delivery system to create cardiac pacemakers.

We tested the ability of human mesenchymal stem cells (hMSCs) to deliver a biological pacemaker to the heart. hMSCs transfected with a cardiac pacemaker gene, mHCN2, by electroporation expressed high levels of Cs+-sensitive current (31.1+/-3.

A freshwater food web model for the combined effects of nutrients and insecticide stress and subsequent recovery.

A microcosm experiment that addressed the interaction between eutrophication processes and contaminants was analyzed using a food web model. Both direct and indirect effects of nutrient additions and a single insecticide application (chlorpyrifos) on biomass dynamics and recovery of functional groups were modeled. Direct toxicant effects on sensitive arthropods could be predicted reasonably well using concentration-response relationships from the laboratory with representative species.

Human mesenchymal stem cells make cardiac connexins and form functional gap junctions.

Human mesenchymal stem cells (hMSCs) are a multipotent cell population with the potential to be a cellular repair or delivery system provided that they communicate with target cells such as cardiac myocytes via gap junctions. Immunostaining revealed typical punctate staining for Cx43 and Cx40 along regions of intimate cell-to-cell contact between hMSCs. The staining patterns for Cx45 rather were typified by granular cytoplasmic staining.

Biological pacemaker implanted in canine left bundle branch provides ventricular escape rhythms that have physiologically acceptable rates.

Background: We hypothesized that administration of the HCN2 gene to the left bundle-branch (LBB) system of intact dogs would provide pacemaker function in the physiological range of heart rates.

Methods And Results: An adenoviral construct incorporating HCN2 and green fluorescent protein (GFP) as a marker was injected via catheter under fluoroscopic control into the posterior division of the LBB. Controls were injected with an adenoviral construct of GFP alone or saline.