Biomedical subjects

J J Weis

Publications and source records attributed to J J Weis.

At least 37 records · Page 2Linked to original sources

PubMed1999

Genomic organization, chromosomal localization, and transcriptional variants of the murine Pactolus gene.

The Pactolus gene encodes a cell surface protein similar to that of the beta integrin subunit family. The murine Pactolus gene is comprised of 16 exons that encompass 24 kb of the genome. The genomic organization of the Pactolus gene is very similar to that described for the human beta2 integrin gene (and deduced for murine beta2 integrin), including a separate exon containing only 5' untranslated sequences. The Pactolus gene was mapped to a terminal region of murine Chromosome (Chr) 16, distinct from the previously mapped site of the beta2 integrin gene on murine Chr 10. The Pactolus gene encodes three distinct transcripts via alternative splicing. The Pactolus A transcript encodes the full-length protein including transmembrane and cytoplasmic domains, while the Pactolus B transcript truncates translation before reaching these membrane-anchoring sequences. A newly discovered form, Pactolus C, is found in neonatal samples (along with Pactolus A) and would also encode a prematurely terminated protein. This form is derived from an alternative splicing event that skips part of exon 11, deletes exon 12, and uses an alternative acceptor site upstream of exon 13. The formation of the Pactolus B and C forms is thus governed by a complex alternative splicing mechanism that is affected by the developmental status of the animal.

5' Untranslated Regions↗

PubMed1999

Monte Carlo approach to the gas-liquid transition in porous materials.

The gas-liquid transition of a "quenched-annealed"(QA) system is studied by grand-canonical Monte Carlo simulation. The "quenched" particles are hard spheres within configurations chosen randomly from those of an equilibrium hard-sphere system at given density. The fluid particles interact with the matrix particles by a hard-core potential and with each other by a hard-core potential and an additional potential of a Lennard-Jones type. Our results are in good qualitative agreement with various theoretical approaches. With increasing matrix density the critical temperature is lowered compared to that of the bulk system and the gap between the gas and liquid densities narrowed. Our simulations confirm, for this QA system, the possibility of two fluid-fluid transitions substituting for the unique gas-liquid transition of the bulk system. They demonstrate the necessity to average over a significant number of matrix realizations in order to obtain a quantitative location of the phase coexistence lines.

Journal Article↗

PubMed1999

Dual role of interleukin-10 in murine Lyme disease: regulation of arthritis severity and host defense.

In the murine model of Lyme disease, C3H/He mice exhibit severe arthritis while C57BL/6N mice exhibit mild lesions when infected with Borrelia burgdorferi. Joint tissues from these two strains of mice harbor similar concentrations of B. burgdorferi, suggesting that the difference in disease severity reflects differences in the magnitude of the inflammatory response to B. burgdorferi lipoproteins. Stimulation of bone marrow macrophages from C3H/HeN mice with the B. burgdorferi lipoprotein OspA resulted in higher-level production of the inflammatory mediators tumor necrosis factor alpha, nitric oxide, and interleukin-6 (IL-6) than that of macrophages from C57BL/6N mice. In contrast, macrophages from C57BL/6N mice consistently produced larger amounts of the anti-inflammatory cytokine IL-10 than did C3H/HeN macrophages. Addition of recombinant IL-10 suppressed the production of inflammatory mediators by macrophages from both strains. IL-10 was found to modulate B. burgdorferi-induced inflammation in vivo, since C57BL/6J mice deficient in IL-10 (IL-10-/-) developed more severe arthritis than wild-type C57BL/6J mice. The increase in arthritis severity was associated with a 10-fold decrease in the number of B. burgdorferi organisms present in ankle tissues from IL-10-/- mice. These findings suggest that in C57BL/6 mice, IL-10-dependent regulation of arthritis severity occurs at the expense of effective control of bacterial numbers.

Animals↗

PubMed1999

Rapid and sensitive quantification of Borrelia burgdorferi-infected mouse tissues by continuous fluorescent monitoring of PCR.

The quantity of Borrelia burgdorferi organisms in tissue samples is an important determinant for infection studies in the mouse model of Lyme disease. This report presents the development of a rapid and sensitive external-standard-based PCR assay for the absolute quantification of B. burgdorferi in mouse tissue samples. The assay uses a double-stranded DNA dye to continuously monitor product formation and in less than an hour was able to quantify samples ranging up to 6 log units in concentration. The PCR efficiencies of the sample and the standard were matched by using a standard composed of purified B. burgdorferi chromosome mixed with tissue-matched mouse genome lacking bacterial DNA. Normalization of B. burgdorferi quantities to the mouse nidogen gene allowed comparison of B. burgdorferi numbers in samples isolated from different tissues and strains. PCR analysis of the chromosomal gene recA in cultured B. burgdorferi was consistent with a single recA per bacterium. The parameters defined in this assay should be applicable to quantification of other organisms, even infectious agents for which no ready source of DNA standard is available. In summary, this report presents a rapid external-standard-based PCR method for the quantification of B. burgdorferi in mouse DNA samples.

Animals↗

PubMed1998

The role of CD14 in signaling mediated by outer membrane lipoproteins of Borrelia burgdorferi.

Borrelia burgdorferi possesses membrane lipoproteins that exhibit stimulatory properties and, consequently, have been implicated in the pathology related to Lyme disease. As CD14 has been shown to mediate signaling by a number of lipid-modified bacterial products, the involvement of CD14 in signaling mediated by two B. burgdorferi lipoproteins, outer surface protein A (OspA) and OspC, was determined. Lipoprotein-mediated induction of nuclear factor-kappaB nuclear translocation and production of IL-8 and IL-6 in HUVEC was enhanced in the presence of serum or soluble rCD14. CD14-specific Abs that block LPS-mediated signaling also inhibited lipoprotein-dependent signaling in HUVEC and neutrophils. The formation of stable complexes between OspA and CD14 was demonstrated by native gel electrophoresis. LPS was found to compete with OspA for binding with CD14, suggesting that LPS and OspA bind similar regions on CD14. The similarity in binding was further supported by the finding that a mutant soluble CD14, lacking the LPS binding site, did not facilitate lipoprotein signaling, nor did it form a complex with OspA. Binding of OspA to CD14 was dependent on the lipid modification, as unlipidated OspA did not form a complex with CD14 or stimulate cells. In contrast, the lipopeptide remaining after proteinase K digestion both formed a complex with CD14 and retained stimulatory properties. These findings indicate that CD14 facilitates bacterial lipoprotein signaling in mammalian cells.

Adjuvants, Immunologic↗

PubMed1998

Identification of pactolus, an integrin beta subunit-like cell-surface protein preferentially expressed by cells of the bone marrow.

We have sought to develop methodologies to identify genes that are preferentially expressed during the differentiation of mast cells from their hematopoietic stem cell precursors. By using a modified differential display protocol, we compared a subset of transcripts expressed in bone marrow cells differentiated into immature mast cells with the exogenous addition of stem cell factor (SCF) or interleukin 3. One gene was identified that was preferentially expressed in the SCF-derived cells and encodes a novel murine integrin beta subunit-like molecule, dubbed Pactolus-1 (Pactolus). Two distinct forms of Pactolus mRNA were detected which, via alternative splicing, are predicted to encode a membrane-bound form and truncated version of the protein. The full-length Pactolus gene product is very similar to a number of beta subunit integrin chains, particularly beta2, with the notable exceptions of the apparent deletion of the metal-binding site within the putative metal ion-dependent adhesion site-like domain of the Pactolus gene product and a cytoplasmic domain that shares no obvious homology to similar domains of the other beta subunit integrin proteins. Although the Pactolus sequence was first identified in immature mast cell samples, screening of murine tissues indicated the highest level of Pactolus expression was found in the bone marrow, suggesting that the expression of Pactolus is confined to immature and maturing bone marrow-derived cells, and that the SCF-derived mast cells are more representative of this state than are the interleukin 3-derived mast cells. Immunoprecipitation of Pactolus revealed a cell-surface protein with an apparent molecular mass of about 95 kDa. Surprisingly, no associating alpha integrin subunit could be identified suggesting that either Pactolus does not associate with another integrin subunit or the association is too weak to be identified. These data suggest that Pactolus represents a gene and gene product related to those of the integrin beta subunits but whose function(s) may be quite distinct from those of the integrin beta subunits.

Alternative Splicing↗

PubMed1998

Distinct characteristics of resistance to Borrelia burgdorferi-induced arthritis in C57BL/6N mice.

Studies of mice infected with Borrelia burgdorferi have indicated that the severity of arthritis is influenced by the genetic composition of the host: the C3H mouse develops severe arthritis while BALB/c and C57BL/6 mice develop mild arthritis. In this study, the effects of increasing infectious dose on the severity of arthritis were determined in these three mouse strains. C3H/He mice developed severe arthritis at all infectious doses, with 100% infection requiring 200 spirochetes. In BALB/cAnN mice, arthritis severity was dependent on infectious dose; symptoms were mild with infection by 200 B. burgdorferi and progressively more severe with increasing infectious dose. Infection of BALB/cAnN mice with 2 x 10(4) B. burgdorferi resulted in arthritis with severity identical to that in C3H/He mice. Spirochete levels in rear ankle joints of C3H/HeJ and C3H/HeN mice were relatively high, as detected by PCR, and did not increase with infectious dose. Spirochete levels in joints from BALB/cAnN mice increased with increasing infectious dose to levels found in severely arthritic C3H/He mice. Thus, resistance to severe arthritis in BALB/cAnN mice was conditional: it could be overcome by high infectious dose and the arthritis became severe when high levels of B. burgdorferi were present in joints. A unique response to increasing infectious dose was seen in C57BL/6N mice, which displayed mild to moderate arthritis at all doses of B. burgdorferi tested, up to 2 x 10(5). At all infectious doses, the levels of spirochetes in ankle joints of C57BL/6N mice were high, equivalent to those found in the severely arthritic C3H/He mice. The arthritis observed in infected (C57BL/6N x C3H/HeN)F1 mice was of severity intermediate between those of the two parental strains. The finding that resistance to severe arthritis in C57BL/6N mice could not be overcome by high infectious doses and was independent of spirochete levels in joints suggested that it was mediated by a distinct mechanism from that operating in BALB/cAnN mice.

Animals↗

PubMed1998

E and P selectins are not required for resistance to severe murine lyme arthritis.

Borrelia burgdorferi-induced arthritis in mice is characterized by tendonitis, synovitis, and inflammatory-cell infiltrate, predominantly of neutrophils. Because genetic deficiency in E and P selectins results in delayed recruitment of neutrophils to sites of inflammation, mice with this deficiency were tested for their response to infection with B. burgdorferi. E and P selectins were not required for the control of B. burgdorferi numbers, nor did deficiency in E and P selectins result in alteration of arthritis severity.

Animals↗

PubMed1998

Quantification of low-copy transcripts by continuous SYBR Green I monitoring during amplification.

Continuous fluorescence observation of amplifying DNA allows rapid and accurate quantification of initial transcript copy number. A simple and generic method for monitoring product synthesis with the double-stranded DNA dye, SYBR Green I provides initial template copy number estimation limited only by stochastic effects. To reach this degree of sensitivity, two methods were used. First, specific products generally have a higher melting temperature than nonspecific products, and therefore, specific product formation was monitored by fluorescence acquisition at temperatures at which only specific products are double-stranded. Second, anti-Taq antibodies were used to reduce nonspecific product generation. The log-linear portion of the fluorescence vs. cycle plot was extended to determine a fractional cycle number at which a threshold fluorescence was obtained. These fractional cycle numbers were plotted against the log of starting template copies to give linear standard curves from purified PCR products, allowing easy estimation of cDNA unknowns over a 10(6)-fold range. A single template molecule per reaction could be distinguished from the absence of template, although stochastic effects increased the variance of concentration estimates below 10 copies. Above 10 copies per reaction, typical replicate coefficients of variation were 6%-37%, with better precision at higher copy numbers.

Animals↗

PubMed1997

CD28 expression by mouse mast cells is modulated by lipopolysaccharide and outer surface protein A lipoprotein from Borrelia burgdorferi.

The concept of costimulation has been best defined in T cells and B cells. However, other cells that respond in an Ag-specific fashion, such as the mast cell, may be regulated by similar mechanisms. We have found that murine mast cells express one such costimulatory molecule, CD28, which was previously defined as a T and NK cell-specific protein. While CD28 transcription appeared to be constitutive in murine mast cells, its cell surface expression was not. CD28 cell surface expression by mast cells derived from bone marrow with stem cell factor (SCF) was dependent upon activation with agents such as LPS, the Borrelia burgdorferi lipoprotein outer surface protein A, and PMA. Peak cell surface expression of CD28 by such cells occurred 24 h after LPS stimulation, 18 h after outer surface protein A stimulation, and 3 h after PMA stimulation. In contrast, mast cells derived from bone marrow with IL-3 did not demonstrate induction-specific cell surface expression of CD28. Instead, maturation of such cells in vitro allowed for the increased cell surface expression of CD28. Peritoneal mast cells cultured in SCF also expressed CD28. Mast cell CD28 was functional, in that cross-linking of CD28 on the surface of the IL-3-derived cells resulted in an increased level of c-jun transcripts. Additionally, cross-linking of CD28 simultaneously with PMA treatment of SCF-derived mast cells resulted in an increased level of IL-13 transcripts. These data suggest that mast cell CD28 has functions similar to those of T cell CD28.

Animals↗

PubMed1997

Expression of the murine CD21 gene is regulated by promoter and intronic sequences.

Murine CD21 gene products are expressed primarily on the surface of B lymphocytes and follicular dendritic cells. To identify the genetic elements that control the tissue-specific expression of the CD21 gene, we analyzed, via transient transfections, the 5' proximal promoter region of the CD21 gene (1272 bp 5' of the initiating ATG). This region possessed strong promoter activity, but it was not tissue specific, in that T cell expression was equivalent to that of B cells. These data suggested that the anticipated tissue-specific control element(s) lies 3' of the initiating ATG. Analysis of a novel minigene construct that possessed both the 5' promoter region and a large region (9 kb) of the CD21 gene 3' of the initiating ATG demonstrated the expected tissue-specific expression. Further analysis using the luciferase reporter system indicated that such control elements reside in the first intron (5.5 kb in size), which separates the exons encoding the signal sequence and the first extracellular short consensus repeat domain of the mature protein. Further dissection of intron 1 demonstrated that the sequences controlling the tissue-specific expression of the murine CD21 gene are contained in the 5' 1.6-kb region of this intron. This 1.6-kb fragment was fractionated into an 800-bp sequence at the 5' end that showed very significant inhibitory activity in both B and T cells and a 3' 800-bp sequence that demonstrated moderate repression in T cells, but enhancer activity in B cells. These data suggest this region of the CD21 gene possesses a number of functionally distinct sites that positively and negatively regulate CD21 gene transcription.

Animals↗

PubMed1997

Borrelia burgdorferi outer surface protein A (OspA) activates and primes human neutrophils.

Lyme disease is caused by infection with the spirochete Borrelia burgdorferi and is characterized by bacterial persistence and inflammation of many host tissues. B. burgdorferi express outer surface lipoproteins, including OspA, with inflammatory properties that could contribute to the localized tissue inflammation. Neutrophils are the predominant infiltrate into the inflamed arthritic joints, and are crucial for controlling the spirochete infection. They may also contribute to the joint pathology associated with Lyme arthritis. This study examines the effect of OspA on the activities of the neutrophil. Picomolar concentrations of OspA induce surface markers associated with neutrophil activation: increased CD10 and CD11b expression; decreased CD62-L expression; and an increased adherence to extracellular matrix. These events were similar in kinetics and magnitude to those induced by the strong activators LPS and FMLP. Like LPS, OspA could prime neutrophils for FMLP-induced release of lysosomal granules and production of superoxide. Thus, models of Lyme arthritis should include the possible contribution of direct activation of neutrophils to both defense and disease.

Antigens, Surface↗

PubMed1997

Pathological manifestations in murine Lyme disease: association with tissue invasion and spirochete persistence.

The clinical manifestations of human Lyme disease present with a spectrum of tissue or organ involvement and severity of symptoms. The murine model of Lyme disease has proved to be an accurate reflection of many of the human symptoms of disease and has been particularly useful for studying development of subacute arthritis and tendonitis. Direct tissue invasion by Borrelia burgdorferi and persistence of high levels of spirochetes in tissues are important components of arthritis development. The outer-surface lipoproteins contain a biologically active lipid-modified moiety with potent ability to stimulate inflammatory cytokine production and other inflammatory mediators such as nitric oxide. Localized inflammation stimulated by these lipoproteins may be the trigger for neutrophil infiltration, synovial proliferation, and other events associated with this arthritis. Invasion of maternal uterine tissue, but not direct invasion of fetal tissue, is associated with low levels of pregnancy loss in mice infected during gestation, consistent with the detrimental effect of inflammatory cytokines on pregnancy.

Animals↗

PubMed1996

Borrelia burgdorferi outer membrane protein A induces nuclear translocation of nuclear factor-kappa B and inflammatory activation in human endothelial cells.

Lyme disease is caused by infection with Borrelia burgdorferi, and is characterized by bacterial persistence and inflammation in a number of host tissues. B. burgdorferi outer surface lipoproteins possess cytokine stimulatory properties that may be responsible for localized inflammation. B. burgdorferi presence is correlated with severity of disease, and the pathology of many tissues, particularly the arthritic joint, is consistent with localized cytokine production. Spirochete invasion of tissues requires interaction with and penetration of vascular endothelium, suggesting endothelial cells may participate in the inflammation of Lyme disease. In this study, outer surface protein A (OspA), a model B. burgdorferi lipoprotein, was found to be a potent stimulant of nuclear factor-kappa B (NF-kappa B) nuclear translocation in human endothelial cells, resulting in nuclear levels similar to those seen in response to known inflammatory mediators. Only the lipid-modified OspA had activity, and activity was not due to contamination with LPS. Nuclear NF-kappa B was detectable within 15 min, suggesting that OspA directly mediates NF-kappa B nuclear translocation. OspA also rapidly up-regulated endothelial cell production of several proteins whose transcription is dependent on NF-kappa B: the cytokine IL-6; the chemokine IL-8; and the adhesion molecules E-selectin, VCAM-1, and ICAM-1. The adhesion molecules were functional, as demonstrated by enhanced binding of neutrophils to OspA-stimulated endothelial monolayers. These data suggest that OspA may initiate synthesis of many proteins essential for localized inflammation via the direct activation of NF-kappa B-dependent transcription. These observations suggest that the interaction of B. burgdorferi lipoproteins with the endothelium may directly induce the inflammation responsible for the symptoms of Lyme disease.

Antigens, Surface↗

PubMed1996

Immunity to Lyme disease: protection, pathology and persistence.

Persistence of the Lyme disease spirochete, Borrelia burgdorferi, in the presence of an active immune response has been well documented. Evidence from the past year indicates that modulation of surface antigens by the spirochete may be a major mechanism for evading the immune response.

Animals↗

PubMed1996

Polymerase chain reaction detection of Lyme disease: correlation with clinical manifestations and serologic responses.

The authors have developed a simple, nested polymerase chain reaction (PCR) assay for amplification of an outer surface protein A (OspA) gene fragment of Borrelia burgdorferi using rapid temperature cycling and ethidium bromide detection on agarose gels, and applied it to the diagnosis of Lyme disease in humans. With denaturing and annealing temperature spikes instead of holds, cycle times were less than 20 minutes for a 30-cycle amplification. Using this rapid cycle PCR technique, as few as 5 spirochetes per mL of phosphate buffered saline were detected. In addition, B burgdorferi DNA was detected from spirochetes that had been spiked into one of several types of human body fluids including serum, synovial fluid, and cerebrospinal fluid (CSF). A number of clinical samples, which had been tested for Lyme immunoglobulin M (IgM) and immunoglobulin G (IgG) antibody were also examined. In 29 serologic positive samples (14 IgG and IgM positive, 9 IgM alone and 6 IgG alone), B burgdorferi DNA was not detected. In contrast, nine serum samples and one synovial fluid from patients with definite clinical features of Lyme disease were found to be negative by EIA and Western blot analysis for IgG and IgM antibody, but contained B burgdorferi DNA, as detected by PCR. Polymerase chain reaction analysis of serum and synovial fluid may be of significant diagnostic value in Lyme disease, especially in the absence of a serologic response in early, partially treated and seronegative chronic disease. This is the first study to report an association between PCR positivity and the absence of a serologic response to Lyme borreliosis.

Base Sequence↗

PubMed1995

Fetal outcome in murine Lyme disease.

Lyme disease is an inflammatory syndrome caused by infection with Borrelia burgdorferi. Although this syndrome has important implications for human pregnancy, little is known about gestational infection with B. burgdorferi. Fetal death occurred in 33 of 280 gestational sacs (12%) in 39 C3H/HeN female mice infected by intradermal injection of B. burgdorferi 4 days after mating (acute infection), compared with 0 of 191 sacs in 25 control mice (P = 0.0001). Forty-six percent of acutely infected mice suffered at least one fetal death, compared with none of the control animals (P = 0.0002). There were no fetal deaths in 18 C3H/HeN mice infected 3 weeks prior to mating (chronic infection). A sensitive PCR technique detected B. burgdorferi DNA in the uteri of acutely infected mice but did not detect DNA in the uteri of controls or chronically infected mice. Spirochete DNA was only rarely detected in fetal tissues, and its presence was not required for fetal death. The inclusion of an internal competitive PCR target indicated that the lack of B. burgdorferi sequences in fetal DNA was not due to the presence of a PCR inhibitor. Histologic analysis of gestational tissues from infected animals demonstrated nonspecific pathology consistent with fetal death. These findings indicate an association between murine fetal death and acute infection with B. burgdorferi early in gestation but not with chronic infection. Our data suggest that fetal death is due to a maternal response to infection rather than fetal infection. These findings could provide an explanation for observations in humans in which sporadic cases of fetal death in women infected with B. burgdorferi during pregnancy have been reported, while previous infection has not been associated with fetal death.

Animals↗

PubMed1995

Nitric oxide production during murine Lyme disease: lack of involvement in host resistance or pathology.

The murine model of Lyme disease was used to determine the role of inflammatory induced nitric oxide (NO) during infection by the spirochete Borrelia burgdorferi. The outer surface lipoproteins of B. burgdorferi are potent stimulators of inflammatory cytokines and NO production by cultured macrophages in vitro. The addition of NO to cultures of B. burgdorferi prevents growth, suggesting a protective role of NO for the infected host. NO is also a crucial effector in some models of arthritis. Therefore, the involvement of NO in controlling B. burgdorferi infection and its participation in pathological development of arthritis were investigated. Both mildly arthritic (BALB/c) and severely arthritic (C3H/HeJ) strains of mice systemically produced high levels of NO 1 week after infection with B. burgdorferi, as determined by urinary nitrate. NO production remained high throughout the infection in BALB/c mice, while in C3H/HeJ mice NO production returned rapidly to uninfected levels. The in vivo inhibitor of the NO synthase enzyme NG-L-monomethyl arginine (LMMA) was given to mice to investigate whether decreasing NO production would alter the course of disease. LMMA effectively blocked NO production in infected mice; however, there was no significant difference in arthritis development, spirochete infection of tissues, or production of specific antibody in LMMA-treated mice. These results indicate that B. burgdorferi is able to persist in the host even in the presence of high levels of NO. Furthermore, NO is not involved in the control of spirochete infection of tissues, nor is it involved in the development of arthritis. The potent activity of NO against intracellular pathogens and the in vivo resistance of B. burgdorferi to NO suggest that this organism is not located in an intracellular compartment during an essential portion of its infection of the mammalian host.

Animals↗