Analysis of outer membrane proteins which are associated with growth of Bacteroides thetaiotaomicron on chondroitin sulfate.

By analyzing outer membrane proteins of Bacteroides thetaiotaomicron on two-dimensional polyacrylamide gels, we were able to identify 10 protein spots that were associated with growth on chondroitin sulfate but not with growth on glucuronic acid or other monosaccharides. These proteins were distinct from the outer membrane polypeptides that were associated with growth on two other negatively charged polysaccharides, polygalacturonic acid and heparin. Of the 10 protein spots that were associated with growth on chondroitin sulfate, 4 could be detected on immunoblots with antiserum that had been raised against outer membranes from bacteria grown on chondroitin sulfate and then cross-adsorbed with membranes from bacteria grown on glucose. Synthesis of these four proteins appeared to be regulated coordinately with synthesis of the two enzymes that degrade chondroitin sulfate, chondroitin lyase I and II. Although one of the four proteins (Mr 110,000) was similar in molecular weight to the chondroitin lyases, the cross-adsorbed antiserum which detected this outer membrane protein did not cross-react with either of these two enzymes.     

Vacuolar ion currents in the primitive green algaEremosphaera viridis: The electrical properties are suggestive of both the Characeae and higher plants

Summary The electrical properties of the vacuolar membrane of the primitive green algaEremosphaera virdis were investigated using the patch-clamp technique. In whole vacuole measurements two types of transport systems with long activation time-constants were identified. The first, showing marked outward rectification, was activated by an increase in the cytosolic calcium concentration. Furthermore, it displayed sensitivity to micromolar concentrations of the anion channel blocker Zn²⁺ and to acidification of the cytosol. In contrast, the second time-activated current component was almost insensitive to changes in cytosolic pH and was blocked by the potassium channel inhibitor TEA. In addition to these slowly activating current components, the vacuolar membrane contained at least two further transport systems, responsible for an instantaneous current. These two current components were distinguished by their different sensitivity to protons, cytosolic calcium, and TEA. Comparing these electrical properties to those observed in vacuoles of higher plants or in cytoplasmic droplets from characean algae, respectively, it seems thatEremosphaera is intermediate, corresponding to the systematic position of this simple green alga.Abbreviations [Ca²⁺]_cyt cytosolic free calcium concentration - EGTA ethyleneglycol-bis(-aminoethylether)N,N,N,N-tetraacetic acid - HEPES N-[2-hydroxyethyl]piperazine-N-[2-ethanesulfonic acid] - I electric current - IRC inward rectifying current - MES 2-[N-morpholino]ethanesulfonic acid - ORC outward rectifying current - pH_cyt cytosolic pH - pH_vac vacuolar pH - P_o open probability - P_x permeability coefficient of ion species X - TEA tetraethylammonium chloride - Tris tris[hydroxymethyl]aminomethane - V voltage     

Evolution of the ATP-binding-cassette transmembrane transporters of vertebrates

The ATP-binding-cassette transmembrane transporters (ABC transporters) known from vertebrates belong to four major subfamilies: (1) the P- glycoproteins (Pgp); (2) the cystic fibrosis transmembrane conductance regulators (CFTR); (3) the Tap proteins encoded with the major histocompatibility complex of mammals; and (4) the peroxisomal membrane proteins. Both Pgp and CFTR have a structure suggesting a past internal gene duplication; a phylogenetic analysis indicated that these duplications occurred independently, while an independent tandem gene duplication occurred in the case of the Tap family. Both the Pgp and Tap proteins show evidence of relationship to bacterial ABC transporters lacking internal duplication, and both are significantly more closely related to the HlyB and MsbA families of transporters from purple bacteria than they are to ABC transporters from nonpurple bacteria. The simplest hypothesis to explain this observation is that eukaryotic Pgp and Tap genes are descended from a mitochondrial gene or genes that were subsequently translocated to the nuclear genome. The Pgp genes of eukaryotes are characterized by a remarkable degree of convergent evolution between the ATP-binding cassettes of their N- terminal and C-terminal halves, whereas no such convergence is seen between the two halves of CFTR genes or between the duplicated Tap genes. Exon 13 of the CFTR gene, which encodes a putative regulatory domain not found in other ABC transporters apart from CFTR, showed high levels of both synonymous and nonsynonymous difference in comparisons among different mammalian species, suggesting that this region is a mutational hot spot.      

Evidence for the presence of β-lactamase inStreptomyces glaucescens and its inhibition by sodium clavulanate

Streptomyces glaucescens is shown to possess -lactamase activity which is inhibitable by clavulanate. This is important in regard to its use as a cloning host for enzymes of \-lactam biosynthesis.     

Mycoplasma pneumoniae Pneumonia—Experience at a Referral Center

Mycoplasma pneumoniae pneumonia is usually a benign illness, and respiratory complications and extrapulmonary manifestations occur rarely. In this series, patients admitted to a referral hospital with this disorder had unusual symptoms, signs and findings on chest roentgenograms and laboratory studies. Pneumonia was often severe and extrapulmonary manifestations were frequent, resulting in prolonged hospital stays and illnesses. Although this extreme end of the spectrum of disease caused by M pneumoniae is not representative of this type of pneumonia as seen in outpatients, it is important to realize that patients admitted to hospital with severe, complicated pneumonia frequently have unusual manifestations of a common disease.     

Clinical determinants of early spontaneous conversion to sinus rhythm in patients with atrial fibrillation

Netherlands Heart Journal - The current standard of care for acute atrial fibrillation (AF) focuses primarily on immediate restoration of sinus rhythm by cardioversion, although AF often terminates...     

Three-Dimensional Trabecular Alignment Model

The Shear-slip Mesh Update Method (SSMUM) is being used in flow simulations involving large but regular displacements of one or more boundaries of the computational domain. We follow up the earlier discussion of the method with notes on practical implementation aspects. In order to establish a benchmark problem for this class of flow problems, we define and report results from a two-dimensional viscous flow around a rotating stirrer in a square chamber. The application potential of the method is demonstrated in the context of biomedical design problem, as we perform an analysis of blood flow in a centrifugal left ventricular assist device, or blood pump, which involves a rotating impeller in a non-axisymmetric housing.