Legionella gormanii sp. nov

A new species of Legionella was isolated from soil collected from a creek bank. The name Legionella gormanii sp. nov. is proposed.     

Spontaneous waves in the dentate gyrus of slices from the ventral hippocampus

Spontaneous negative-going potentials occurring at an average frequency of 0.7 Hz were recorded from the dentate gyrus of slices prepared from the temporal hippocampus of young adult rats. These events (here termed "dentate waves") in several respects resembled the dentate spikes described for freely moving rats during immobile behaviors and slow-wave sleep. Action potentials were observed on the descending portion of the in vitro waves and, as expected from this, whole cell recordings established that the waves were composed of depolarizing currents. Dentate waves appeared to be locally generated within the granule cell layer and were greatly reduced by antagonists of AMPA-type glutamate receptors or by lesions to the entorhinal cortex. Simultaneous recordings indicated that the waves were often synchronized in the inner and outer blades of the dentate gyrus. Knife cuts through the perforant path and the commissural/associational system did not eliminate synchronization, leaving electrotonic propagation via gap junctions as its probable cause. In accord with this, cuts that separated the two blades of the dentate eliminated synchronization between them, and a compound that inhibits gap junctions reduced wave activity. Dentate waves were regularly accompanied by sharp waves in field CA3 and were reduced in size by the acetylcholinesterase inhibitor, physostigmine. It is hypothesized that dentate waves occur when spontaneous glutamate release from dentate afferents produces action potentials in neighboring granule cells that then summate electrotonically into a population event; once initiated, the waves propagate, again electrotonically, and thereby engage a significant portion of the granule cell population.     

Use of in vivo-induced antigen technology for identification of Escherichia coli O157:H7 proteins expressed during human infection

Using in vivo-induced antigen technology (IVIAT), a modified immunoscreening technique that circumvents the need for animal models, we directly identified immunogenic Escherichia coli O157:H7 (O157) proteins expressed either specifically during human infection but not during growth under standard laboratory conditions or at significantly higher levels in vivo than in vitro. IVIAT identified 223 O157 proteins expressed during human infection, several of which were unique to this study. These in vivo-induced (ivi) proteins, encoded by ivi genes, mapped to the backbone, O islands (OIs), and pO157. Lack of in vitro expression of O157-specific ivi proteins was confirmed by proteomic analysis of a mid-exponential-phase culture of E. coli O157 grown in LB broth. Because ivi proteins are expressed in response to specific cues during infection and might help pathogens adapt to and counter hostile in vivo environments, those identified in this study are potential targets for drug and vaccine development. Also, such proteins may be exploited as markers of O157 infection in stool specimens.     

Ontogeny, distribution and function of CD38-expressing B lymphocytes in mice

Analysis of expression of CD38, CD45R (B220), IgM and IgD on splenic B lymphocytes from mice of different ages demonstrated CD38 on both immature (B220(+), BCR(-)) and mature (B220(+), BCR(+)) B lymphocytes. Similarly, CD38 is expressed as early as B220 on the surface of progenitor B cells in the bone marrow. In spite of expressing of CD38 and IgM, neonatal B cells, in contrast to the adult, failed to proliferate to either anti-CD38 or anti-IgM cross-linking when IL-4 was present. They did, however, respond to LPS and anti-CD40, and by 2 weeks of age they began to respond to anti-CD38 and anti-IgM, reaching adult B cell levels by 4 weeks. Although the distribution of CD38 on adult B cells from most different lymphoid compartments was broadly similar, significantly higher levels of CD38 were expressed on peritoneal B lymphocytes. A detailed analysis, using IgM / IgD ratio and staining with anti-CD5 confirmed that B1 lymphocytes were expressing a high level of CD38. Interestingly, both immature B cells and peritoneal B1 lymphocytes were unresponsive to anti-CD38. However, they were activated by LPS or anti-CD40.     

Bulk and Solution Copolymerization of Butyl Acrylate/Methyl Methacrylate at Elevated Temperatures

A series of bulk and solution (in toluene) copolymerizations of butyl acrylate/methyl methacrylate were performed independently at two laboratories. The runs were at elevated temperatures ranging from 90 to 140 °C conducted to high conversion levels, and samples were characterized for conversion, cumulative copolymer composition and number‐ and weight‐average molecular weights and distribution. Variation of the comonomer feed composition, temperature, and the solvent, initiator and chain transfer agent concentrations was studied. Using a mechanistic model, conversion data were predicted to high conversions using terminal model kinetics at 90 and 115 °C. The copolymer composition data conformed to the terminal kinetic model over the entire temperature range. Solvent effects were reflected by changes in the butyl acrylate rate constants.

Composition vs. conversion. Effect of feed composition for runs at 140 °C.     

Attenuated poxvirus expressing three immunodominant CMV antigens as a vaccine strategy for CMV infection.

BACKGROUND: Human cytomegalovirus (CMV) infection is an important risk factor in the post-transplant (Tx) recovery phase for both hematopoietic stem cell Tx (HSCT) and solid organ Tx (SOT) recipients. CMV infection may be prevented or controlled by simultaneously inducing both CMV-specific neutralizing antibody (nAb) and cellular immunity. Soluble (s) UL55 (surface glycoprotein), UL83 (tegument protein) and UL123/e4 (nuclear protein) are immunodominant in eliciting both CMV nAb and cellular immunity. An attenuated poxvirus, modified vaccinia Ankara (MVA) was selected to develop this vaccine strategy in Tx recipients, because of its clinical safety record, large foreign gene capacity, and capability to activate strong humoral and cellular immune responses against recombinant antigens. OBJECTIVES: A subunit vaccine that targets multiple CMV antigens will be used to gain maximal coverage and protective function against CMV infection. rMVA simultaneously expressing sUL55, UL83 and UL123/e4 will be generated, and humoral and cellular immunity it elicits will be characterized, after murine immunization and in vitro to amplify clinical recall responses. STUDY DESIGN: rMVA will be constructed in two steps using UL123/e4-pLW22 followed by sUL55-UL83-pLW51 transfer plasmids. Western blots will be used to characterize expression levels of each antigen. Primary immunity will be evaluated in mouse models, while recall responses to the virally expressed CMV antigens will be assessed in human peripheral blood. RESULTS: We generated CMV-MVA via homologous recombination, and demonstrated high expression levels of sUL55, UL83 and UL123/e4 by Western blot. CMV-MVA immunization potently induced both humoral and cellular immunity to sUL55, UL83 and UL123 after murine immunization, and cellular immunity to UL83 and UL123 by in vitro amplification of T cell recall responses in human PBMC. CONCLUSIONS: rMVA promotes high level expression of three immunodominant CMV antigens, which is reflected in results of immunization studies in which high titers of UL55-specific antibodies and CD4+ T-help are detected, as well as high levels of UL83-specific and moderate levels of UL123-specific CD8+ CTL.     

The influence of variations in electrolyte concentration on skin potential level and response amplitude

The application of electrolytes of low concentration to the palm causes hydration of the epidermis with swelling of the skin, closure of the sweat gland pores, and reduction of skin potential level (SPL). Solutions of high concentration are known not to produce poral closure. Previous reports of increases in SPL with increased concentration of electrolyte did not control for possible effects of hydration associated with differences in concentration. The experiments reported here compared the effects of varying concentration with and without holding hydration constant. The results indicated that the effect of concentration on both positive and negative skin potential response amplitude can be attributed to hydration, whereas the effect on SPL is not influenced by hydration. The effect of concentration on SPL was the same whether measured during rest or during periods of considerable sweat gland activity. This last finding is difficult to interpret in terms of the traditional assumption that the membrane responsible for the concentration-potential effect lies deep in the epidermis, and it was suggested that the membrane may be located in the upper sweat gland duct.     

Metabolic depression and myocardial potassium

Summary The action potential duration (APD) of guinea pig atrial muscle responded qualitatively to metabolic depression and altered glucose concentration as shown previously for papillary muscle. Both preparations lost potassium and gained sodium during 8 h anoxic incubations and these changes were partially prevented by 50 mM glucose. Experiments with potassium⁴² indicated that anoxia-induced loss of potassium was not primarily due to an increased efflux but to a decreased influx. Stimulation did not increase potassium⁴² efflux from atria but caused some increase in potassium loss. The ATP content of atria and ventricular muscle decreased rapidly during anoxic incubation but was maintained at a significantly higher level in the presence of 50 mM glucose. Since muscle potassium levels following 8 h of anoxic incubation were incompatible with observed resting potentials, the results support the concept of either an electrogenic sodium pump or the intracellular compartmentalization of potassium. In addition, the anoxia-induced reduction of action potential duration does not appear to be associated with an increase in potassium⁴² efflux.This work was supported by grants from the Medical Research Council of Canada and the Canadian Heart Foundation.     

Low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) of thymus

This report describes a low-grade B-cell lymphoma of mucosa associated lymphoid tissue (MALT) involving the thymus of a 63-year-old woman with features suggestive of a connective tissue disease. Sections of the thymic lesion and of a lung biopsy performed at the same operation were examined histologically and by immunohistochemistry using the monoclonal antibodies CD45, CD20, CD79a, CD3, CD45RO, and AE1/AE3. Polymerase chain reaction (PCR) for immunoglobulin heavy chain gene rearrangement was also performed. The dense infiltrate of small lymphoid cells intimately admixed with ramifying epithelial elements, some of which had undergone cystic change, closely resembled a thymoma. The lymphoid infiltrate comprised centrocyte-like cells, small lymphocytes, plasma cells, and blasts. Most of the lymphoid cells were immunoreactive with the B-cell markers CD20 and CD79a, and PCR showed clonal immunoglobulin heavy chain gene rearrangement. The lung biopsy showed dense infiltration by small lymphoid cells, morphologically suggestive of lymphoid interstitial pneumonia. However, PCR showed a weak band in the amplification for immunoglobulin heavy chain gene rearrangement, identical to that within the thymus and suggesting either recirculation of cells to accumulated MALT or subhistological lymphoma. MALT lymphoma may rarely involve the thymus, and pathologists should be aware of this to avoid misdiagnosis as a thymoma. Immunohistochemical and/or molecular studies are of value in this regard. MALT lymphomas of the thymus, common with those arising in other organs, may develop in the setting of a connective tissue disease.