Electrophysiological investigation of microdissected gastric glands of bullfrog II. Basolateral membrane properties in the presence of histamine

Following the technical approach described in the preceding publication we have investigated if, and how, stimulation of gastric HCl secretion affects the basolateral ion transport properties of oxyntopeptic cells of Rana catesbeiana stomach. To this end microdissected gastric glands were punctured with conventional or H⁺-sensitive glass microelectrodes and the effects of changing bath ion concentrations on the cell membrane potential (V _b) and cell pH (pH_i) were determined. Except for a transient alkalinization, histamine (0.5 mmol/l) did not significantly affect V _b or pH_i. The latter averaged 7.18±0.03 (mean±SEM, n=5) under resting conditions (0.1 mmol/l cimetidine) and 7.21±0.07 (n=5) in the presence of histamine. In addition, neither the initial velocity nor the final steady-state value of the cell alkalinization following a 101 reduction of bath Cl^– concentration changed in the presence of histamine, and the same holds true for the cell acidification following a 101 reduction of bath HCO₃ ^– concentration. These observations indicate that the basolateral Cl^–/HCO₃ ^– exchanger was not stimulated by histamine, and that no other base transporters were activated. By contrast, the V _b response to elevation of bath K ⁺ concentration decreased, and so did the initial depolarizing V _b response to bath Cl^– substitution, while the secondary hyperpolarizing response increased. The latter observations are compatible with the notion that stimulation by histamine reduced a pH-insensitive part of the basolateral K⁺ conductance and reduced also the basolateral Cl^– conductance.     

The common functional C(-159)T polymorphism within the promoter region of the lipopolysaccharide receptor CD14 is not associated with sepsis development or mortality

Sepsis is characterised by a systemic inflammatory response to bacterial products during infection, which interestingly both in humans and animal models is gender associated with a higher susceptibility of males than females. The CD14 receptor is involved in activation of cells by lipopolysaccharides released from Gram-negative bacteria and, as recently shown, also by products of Gram-positive bacteria (e.g., peptidoglycans and lipoteichoic acid). The functional relevance of a C(-159)T CD14 polymorphism recently has been shown based on correlation of the T allele to higher plasma levels of soluble CD14, and higher membrane expression on monocytes. We, therefore, now analysed this CD14 polymorphism in 204 patients with severe sepsis and 247 controls. No significant difference of allele frequencies was observed between sepsis patients and controls neither for males nor females. Mortality also was not associated with the polymorphism studied. This may suggest that other mechanisms for lipopolysaccharide recognition, such as the recently described Toll-like receptors are important for inflammatory cell activation in sepsis.     

Prevalence and characterization of a binary toxin (actin-specific ADP-ribosyltransferase) from Clostridium difficile

In addition to the two large clostridial cytotoxins (TcdA and TcdB), some strains of Clostridium difficile also produce an actin-specific ADP-ribosyltransferase, called binary toxin CDT. We used a PCR method and Southern blotting for the detection of genes encoding the enzymatic (CDTa) and binding (CDTb) components of the binary toxin in 369 strains isolated from patients with suspected C. difficile-associated diarrhea or colitis. Twenty-two strains (a prevalence of 6%) harbored both genes. When binary toxin production was assessed by Western blotting, 19 of the 22 strains reacted with antisera against the iota toxin of C. perfringens (anti-Ia and anti-Ib). Additionally, binary toxin activity, detected by the ADP-ribosyltransferase assay, was present in only 17 of the 22 strains. Subsequently, all 22 binary toxin-positive strains were tested for the production of toxins TcdA and TcdB, toxinotyped, and characterized by serogrouping, PCR ribotyping, arbitrarily primed PCR, and pulsed-field gel electrophoresis. All binary toxin-positive strains also produced TcdB and/or TcdA. However, they had significant changes in the tcdA and tcdB genes and belonged to variant toxinotypes III, IV, V, VII, IX, and XIII. We could differentiate 16 profiles by using typing methods, indicating that most of the binary toxin-positive strains were unrelated.     

Immuno-electronmicroscopy of fimbriae-like structures on Bordetella pertussis serotype 1.3

Fimbriae-like filaments were demonstrated on the surface of Bordetella pertussis, serotype 1.3, by negative staining and electronmicroscopy. Immunoelectronmicroscopy with a monoclonal antibody specific for strains possessing agglutinogen 3, and colloidal gold, gave strong labelling of these structures. However, incubation with adsorbed polyclonal anti-agglutinogen 3 serum gave only weak labelling of the distal parts of the filaments and of the bacterial surface. The different binding patterns of the two antisera suggested that the epitopes involved were dissimilar. Thus, agglutinogen 3, as defined by conventional adsorbed sera, appeared to be associated with the fimbriae-like structures but was not necessarily identical to the fimbrial subunit protein. The monoclonal antibody, however was more likely directed against the subunits of the fimbriae-like structures on serotype 1.3 bacteria.     

Thermal acclimation of neonates to prolonged cool exposure as regards sleep stages

The thermal responses of neonates during a cool acclimation period were studied with regard to sleep stages. Sleep stages, body temperatures and metabolic rate (VO2) were studied for seven neonates nursed in incubators and exposed to a cool temperature (thermoneutrality minus 2 degrees C) for 75 h. Each recording session lasted 3 h in the morning: firstly under thermoneutral baseline conditions, then during the first and last 3-h periods of the cool acclimation and finally during the last 3 h of a 24-h recovery period. Sleep structure was modified during the initial hours of cool exposure: the percentage of active sleep increased (AS: +13%, P = 0.028) at the expense of quiet sleep (QS: -11%, P = 0.043). This alteration in sleep structure persisted at the end of the acclimation period. Metabolic heat production only increased in the later period of cool acclimation. Throughout the cool exposure, VO2 increased more (P = 0.040) in QS (+33%) than in AS (+20%) so that by the end of the cool period, VO2 levels were similar in both sleep stages. During cool acclimation, the maintenance of homeothermy is related not only to a change in sleep organization but also to modifications in the thermoregulatory processes in both sleep stages. Considering the importance of AS/QS patterns in the neurobehavioral development of neonates, the present results could have clinical implications for the thermal management of neonates.     

Expression of genes in normal human monocytes in response to Aspergillus fumigatus.

The objective of these studies was to investigate genes of importance in the pathogenesis of Aspergillus infections. To do so, we employed microarray methodology to explore gene expression in human monocytes infected with Aspergillus conidia as compared with unstimulated monocytes and those stimulated with lipopolysaccharide (LPS) signaling through TOLL-like receptor 4 (TLR4). We found 997 (P相似文献   

Functional proteomics mapping of a human signaling pathway

Access to the human genome facilitates extensive functional proteomics studies. Here, we present an integrated approach combining large-scale protein interaction mapping, exploration of the interaction network, and cellular functional assays performed on newly identified proteins involved in a human signaling pathway. As a proof of principle, we studied the Smad signaling system, which is regulated by members of the transforming growth factor beta (TGFbeta) superfamily. We used two-hybrid screening to map Smad signaling protein-protein interactions and to establish a network of 755 interactions, involving 591 proteins, 179 of which were poorly or not annotated. The exploration of such complex interaction databases is improved by the use of PIMRider, a dedicated navigation tool accessible through the Web. The biological meaning of this network is illustrated by the presence of 18 known Smad-associated proteins. Functional assays performed in mammalian cells including siRNA knock-down experiments identified eight novel proteins involved in Smad signaling, thus validating this integrated functional proteomics approach.     

Morphologic Study of the Participation of the Complement System in Hyperacute Rejection of Renal Xenotransplants

The role of polymorphonuclear leukocyte (PMN) and platelet infiltration in the hyperacute rejection of renal xenotransplants was studied. In a first group, a dog kidney was grafted to rabbit recipients with intact immune adherence and chemotaxis. A second group included recipients depleted of PMN's with nitrogen mustard, and in a third group, immune adherence and chemotaxis were modified by depleting the third component of complement by means of cobra venom factor. Serial kidney biopsies were studied with light and electron microscopic technics. A semiquantitative evaluation of PMN and platelet glomerular infiltration indicated that a reduction in the number of PMN's or platelets is associated with an increased survival time of the transplanted kidney.     

Jumping translocations in multiple myeloma

Jumping translocations (JT) have been defined as nonreciprocal translocations involving a same donor chromosome arm or chromosome segment onto two or more recipient chromosomes in different cell lines in the same patient, leading to a mosaic karyotype. This definition has been expanded to also include extra copies of a same donor segment on different recipient chromosomes in a single clone. Six patients with multiple myeloma and JT involving chromosome arm 1q were identified among 37 patients presenting with chromosome 1 abnormalities. All six patients had an advanced disease and a short survival. The literature review allowed us to identify 24 additional patients with JT. Chromosomes 16 and 19 were the recipients in 11 (45.8%) and 6 (25%) of these 24 patients, respectively. Breakpoints on the recipient chromosomes were pericentromeric in 46.2% and telomeric in 40.4% of the breakpoints recorded. Since telomeres are made of (TTAGGG)n tandem DNA repeats that are also found in the pericentromeric heterochromatic regions (interstital telomeric sequences), it is presumed that jumping translocations arise through illegimate recombination between telomere repeat sequences and interstitial telomeric sequences.     

Chemokines and soluble adhesion molecules in renal transplant recipients with cytomegalovirus infection

Cytomegalovirus (CMV) infection is associated with leucocyte infiltration in various organs, which supports a role for chemokines and adhesion molecules in the pathogenesis of CMV infection. In a prospectively conducted study of renal transplant recipients, 10 patients with CMV disease, five patients with asymptomatic CMV infection and 10 patients who did not have any CMV infection were included. During CMV infection, and in particular during CMV disease, plasma levels of the chemokines IL-8, macrophage inflammatory protein-1alpha (MIP-1alpha) and monocyte chemotactic protein-1 (MCP-1) and the soluble adhesion molecules vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1) and L-selectin increased and were positively correlated with the degree of CMV pp65 antigenaemia. Furthermore, a decrease in plasma levels of these chemokines and adhesion molecules was observed following ganciclovir therapy in the patients with CMV disease. This could suggest a role for these molecules in the pathogenesis of CMV infection.