Rapid detection of Mycoplasma pneumoniae IgM antibodies in pediatric patients using ImmunoCard Mycoplasma compared to conventional enzyme immunoassays.
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Adolescent↗
Biomedical subjects
J J Dunn
Publications and source records attributed to J J Dunn.
Crystal structure of outer surface protein C (OspC) from the Lyme disease spirochete, Borrelia burgdorferi.
Outer surface protein C (OspC) is a major antigen on the surface of the Lyme disease spirochete, Borrelia burgdorferi, when it is being transmitted to humans. Crystal structures of OspC have been determined for strains HB19 and B31 to 1.8 and 2.5 A resolution, respectively. The three-dimensional structure is predominantly helical. This is in contrast to the structure of OspA, a major surface protein mainly present when spirochetes are residing in the midgut of unfed ticks, which is mostly beta-sheet. The surface of OspC that would project away from the spirochete's membrane has a region of strong negative electrostatic potential which may be involved in binding to positively charged host ligands. This feature is present only on OspCs from strains known to cause invasive human disease.
Amino Acid Sequence↗
Catecholaminergic regulation of Na-K-Cl cotransport in pigmented ciliary epithelium: differences between PE and NPE.
Pigmented (PE) and nonpigmented (NPE) ciliary epithelial cells comprise the ciliary epithelium, the site of aqueous humor formation in the eye. In man, catecholamines increase the rate of aqueous humor formation, but the mechanism underlying these effects is not understood. Recent evidence suggests that Na-K-Cl cotransport plays a central role in blood-to-aqueous chloride transport across ciliary epithelium in cow and rabbit. We therefore investigated whether catecholamines stimulate Na-K-Cl cotransport in human PE cells. Na-K-Cl cotransporter protein was detected as a 170 kDa protein band on immunoblots. Immunofluorescence microscopy detected cotransporter on the basolateral membranes of the PE layer of ciliary epithelium from a human donor. Cotransporter immunofluorescence was also detected in cultured PE cells. Na-K-Cl cotransport activity measured as ouabain-insensitive bumetanide-sensitive(86)Rb uptake was stimulated by isoproterenol 1.6-fold, with an EC(50) = 28 n M and maximal stimulation at 1 microM. Other transport mechanisms involved in(86)Rb uptake were not affected. Stimulation by 1 microM isoproterenol was blocked by 10 n M ICI 118,551, a beta(2)-specific receptor antagonist, whereas the receptor subtype-specific antagonists yohimbine (alpha(2)), prazosin (alpha(1)) and atenolol (beta(1)) were ineffective. Norepinephrine stimulation (EC(50) = 280 n M) was also blocked by ICI 118,551. Dopamine stimulated Na-K-Cl cotransport 1.6-fold with an EC(50) = 14 microM. The dopamine effect could not be blocked by 10 microM SCH 23390, a D1-antagonist, but was abolished by ICI 118,551. Forskolin and CPT-cAMP stimulated Na-K-Cl cotransport 1.79- and 1.71-fold, respectively, whereas the inactive forskolin analogue 1,9-dideoxyforskolin had no effect. However, high concentrations of the PKA inhibitors PKI amide 14-22 and KT 5720 were needed to inhibit both PKA activity in cell lysates and isoproterenol stimulation of cotransport. This finding may indicate the presence of a novel PKA isoform in PE cells. Inhibitors of other protein kinases, including myosin light chain kinase, protein kinase G, calmodulin-dependent kinase and tyrosine kinase, were without effect on stimulated Na-K-Cl cotransport. When EC(50)s for catecholaminergic stimulations of Na-K-Cl cotransport in PE were compared to those in NPE, values within five-fold of one another were seen for isoproterenol and norepinephrine. In contrast, dopamine was 28-fold more potent in NPE than in PE. The data suggest that both PE and NPE possess beta(2)adrenergic receptors, but only NPE cells possess dopamine D1 receptors linked to Na-K-Cl cotransport.
Catecholamines↗
Crystallization and preliminary X-ray analysis of Borrelia burgdorferi outer surface protein C (OspC).
Single crystals of the outer surface protein C (OspC) from Borrelia burgdorferi HB19 have been obtained by the vapor-diffusion method. These crystals belong to space group P2(1), with unit-cell parameters a = 66.218, b = 46.113, c = 112.079 A, beta = 99.30 degrees, and diffract to at least 2.2 A resolution. Native data have been collected from flash-frozen crystals at the National Synchrotron facility of Brookhaven National Laboratory. There are two dimers per asymmetric unit, related by a non-crystallographic twofold axis and a pseudo-translational symmetry.
Amino Acid Sequence↗
Frameshift mutation in PRKDC, the gene for DNA-PKcs, in the DNA repair-defective, human, glioma-derived cell line M059J.
Anderson, C. W., Dunn, J. J., Freimuth, P. I., Galloway, A. M. and Allalunis-Turner, M. J. Frameshift Mutation in PRKDC, the Gene for DNA-PKcs, in the DNA Repair-Defective, Human, Glioma-Derived Cell Line M059J. Radiat. Res. 156, 2-9 (2001). The glioma-derived cell line M059J is hypersensitive to ionizing radiation, lacks DNA-PK activity, and fails to express protein for the catalytic subunit, DNA-PKcs, while a sister cell line, M059K, derived from the same tumor, has normal DNA-PK activity. Both cell lines are near pentaploid and have multiple copies of chromosome 8, the chromosome on which the DNA-PKcs gene, PRKDC, is located. Sequence analysis of PCR-amplified exons revealed the loss in M059J cells of a single "A" nucleotide in exon 32, corresponding to the first nucleotide of codon 1351 (ACC, Thr) of PRKDC. Loss of the "A" nucleotide would terminate the DNA-PKcs reading frame early in exon 33. DNA from M059K cells had only the wild-type sequence. An analysis of sequences surrounding PRKDC exon 32 from 87 unrelated individuals revealed no polymorphic nucleotides except for a triplet repeat near the 3' end of this exon; no individual had a frameshift mutation in exon 32. No other sequence differences in PRKDC between M059J and M059K cells were observed in approximately 15,000 bp of genomic sequence including the sequences of exons 5 through 38 and surrounding intron sequence, suggesting a possible reduction to homozygosity at this locus prior to acquisition of the mutation leading to the M059J cell line.
Catalytic Domain↗
Immunolocalization of the Na-K-Cl cotransporter in bovine ciliary epithelium.
PURPOSE: Recent evidence suggests that Na-K-Cl cotransport plays a major role in blood-to-aqueous anion transport across the ciliary body epithelium. The present study was undertaken to determine the location of the Na-K-Cl cotransporter in fixed sections of bovine eye. METHODS: Sections of paraformaldehyde-fixed adult and calf bovine eyes were treated with a monoclonal antibody to mammalian Na-K-Cl cotransporter and a fluorescent secondary antibody and examined under a fluorescent microscope. Na-K-Cl cotransporter protein was detected on immunoblots of dissected tissue and purified nonpigmented ciliary epithelial (NPE) and pigmented ciliary epithelial (PE) cells. RESULTS: Cotransporter immunofluorescence was most intense along the basolateral surfaces of the PE cells. Anterior pars plicata possessed the greatest PE immunofluorescence, and this diminished posteriorly toward the pars plana. Quantitation of immunofluorescence images indicated 7- to 10-fold more cotransporter protein in pars plicata PE than in pars plana PE. Diffuse cytoplasmic fluorescence was seen in the NPE cells, which was also brightest in anterior pars plicata. Immunoblots of separated PE and NPE cells from anterior pars plicata showed that PE contain four times more 170-kDa cotransporter protein than NPE. This confirmed fluorescence quantitation estimates. Cotransporter was barely detectable in cells isolated from pars plana in either cell layer. Immunoblots of the Na,K-ATPase catalytic (alpha) subunit in separated NPE and PE cells showed that NPE cells possessed approximately eight times more alpha subunit protein than PE. Immunofluorescence indicated a similar distribution of alpha subunits and indicated a basolateral membrane location for the subunit on both cell types. Na-K-Cl cotransporter fluorescence patterns showed more variability in adult animals than in calves, which may be related to aging and/or disease. Distinctive patterns of cotransporter fluorescence were also seen in the cornea, iris, and retina. CONCLUSIONS: Localization of the Na-K-Cl cotransporter to the plasma membrane on the blood side of the ciliary epithelium tight junctions supports a role for the Na-K-Cl cotransporter in ciliary epithelium as a chloride entry mechanism involved in blood-to-aqueous chloride transport. The concentration of Na,K-ATPase catalytic subunits on NPE basolateral membranes could provide net Na(+) efflux into the aqueous humor.
Animals↗
Structural identification of a key protective B-cell epitope in Lyme disease antigen OspA.
Outer surface protein A (OspA) is a major lipoprotein of the Borrelia burgdorferi spirochete, the causative agent of Lyme disease. Vaccination with OspA generates an immune response that can prevent bacterial transmission to a mammalian host during the attachment of an infected tick. However, the protective capacity of immune sera cannot be predicted by measuring total anti-OspA antibody. The murine monoclonal antibody LA-2 defines an important protective B-cell epitope of OspA against which protective sera have strong levels of reactivity. We have now mapped the LA-2 epitope of OspA using both NMR chemical-shift perturbation measurements in solution and X-ray crystal structure determination. LA-2 recognizes the three surface-exposed loops of the C-terminal domain of OspA that are on the tip of the elongated molecule most distant from the lipid-modified N terminus. The structure suggests that the natural variation at OspA sequence position 208 in the first loop is a major limiting factor for antibody cross-reactivity between different Lyme disease-causing Borrelia strains. The unusual Fab-dominated lattice of the crystal also permits a rare view of antigen flexibility within an antigen:antibody complex. These results provide a rationale for improvements in OspA-based vaccines and suggest possible designs for more direct tests of antibody protective levels in vaccinated individuals.
Amino Acid Sequence↗
Stable enterovirus 5' nontranslated region over a 7-year period in a patient with agammaglobulinemia and chronic infection.
Cerebrospinal fluid samples obtained 7 years apart from a patient with chronic meningoencephalitis and underlying agammaglobulinemia were examined to determine enteroviral genotypic variability. From each sample, amplicons spanning 496 nucleotides within the 5' nontranslated region were generated directly from the cerebrospinal fluid and analyzed. A consensus sequence derived from 3 clones of each amplicon revealed only 7 nucleotide changes over the 7-year period within the region studied. The observed 5' nontranslated region mutation rate in this patient ( approximately 0.2% per year) was significantly lower than mutation rates reported for the poliovirus genome.
5' Untranslated Regions↗
Recombinant chimeric Borrelia proteins for diagnosis of Lyme disease.
Current serologic Lyme disease tests use whole borrelia cells as the source of antigen. These assays are difficult to standardize and to optimize for sensitivity and specificity. To help solve these problems, we constructed a library of recombinant chimeric proteins composed of portions of key antigens of Borrelia burgdorferi. These proteins were then used to develop an enzyme-linked immunosorbent assay. We compared our assay with the most sensitive of three whole-cell borrelia assays. We found that the recombinant assay could detect antibodies significantly better from early Lyme disease sera (P<0.05), and had the same sensitivity for late Lyme disease sera, as the most sensitive whole-cell borrelia assay. On potentially cross-reactive sera, the recombinant assay was more specific, but not significantly so, than the best whole-cell borrelia assay. Optimization of the recombinant assay offers the potential for a significant improvement in both sensitivity and specificity.
Antibodies, Bacterial↗
Genomic determinants of cardiovirulence in coxsackievirus B3 clinical isolates: localization to the 5' nontranslated region.
Coxsackievirus B3 (CVB3) infections can cause myocarditis in humans and are implicated in the pathogenesis of dilated cardiomyopathy. The natural genetic determinants of cardiovirulence for CVB3 have not been identified, although using strains engineered in the laboratory, cardiovirulence determinants have been identified in the CVB3 5' nontranslated region (5'NTR) and capsid. The myocarditic phenotypes of two CVB3 clinical isolates were determined using an established murine model of inflammatory heart disease. The 5'NTRs and capsid proteins of the noncardiovirulent CVB3/CO strain and cardiovirulent CVB3/AS strain were examined to determine their influence on the cardiovirulence phenotype. Six intratypic chimeric viruses were constructed in which 5'NTR and capsid sequences of the infectious cDNA copy of the cardiovirulent CVB3/20 genome were replaced by homologous sequences from CVB3/CO or CVB3/AS. Chimeric strains were tested for cardiovirulence by inoculation of C3H/HeJ mice. Sections of hearts removed at 10 days postinoculation were examined for evidence of myocarditis by light microscopy and assayed for the presence of virus. Replacement of the CVB3/20 capsid coding region by that from the homologous region of CVB3/CO resulted in no change in the cardiovirulent CVB3/20 phenotype, with virus recoverable from the heart at 10 days postinoculation. However, recombinant virus containing the CVB3/CO 5'NTR alone or the 5'NTR and capsid sequences together were not myocarditic, and infectious virus was not recovered from the myocardium. Chimeric viruses containing the CVB3/AS 5'NTR alone, capsid sequence alone, or both together preserved the myocarditic phenotype. These data support the 5'NTR as the primary site in the determination of the natural cardiovirulence phenotype of CVB3.
5' Untranslated Regions↗
The role of NaKCl cotransport in blood-to-aqueous chloride fluxes across rabbit ciliary epithelium.
PURPOSE: To evaluate the role of NaKCl cotransport in short-circuit current (Isc) and chloride fluxes across rabbit ciliary epithelium mounted in a Ussing-type chamber. METHODS: Bilayered intact ciliary epithelium free of stroma was obtained after perfusion and dissection of rabbit eyes and mounted in an Ussing-type chamber. The effects of bumetanide and other drugs on Isc and transepithelial 36Cl fluxes in bicarbonate-containing Ringer's were determined. Immunoblot analysis was performed by standard techniques. RESULTS: Bumetanide (100 microM) applied to the blood (pigmented epithelium [PE]) side of the ciliary bilayer caused a dose-dependent decrease in Isc from 18.2 +/- 2.2 to 10.4 +/- 1.4 microA/cm2 (43%). Bumetanide applied to the aqueous (nonpigmented epithelium [NPE]) side of the tissue inhibited Isc by only 12%. Immunoblots of dissected NPE and PE tissue probed with an antibody to mammalian NaKCl cotransporter detected approximately 10 times more NaKCl cotransporter protein in PE than in NPE. 36Cl flux studies revealed a PE-to-NPE chloride flux of 180.3 +/- 37.2 microEq/cm2 per hour and an NPE-to-PE flux of 72.3 +/- 22.9 microEq/cm2 per hour, indicating a net PE-to-NPE flux of 108.0 +/- 31.3 microEq/cm2 per hour across rabbit ciliary epithelium. Bumetanide inhibited the PE-to-NPE chloride flux by 52% but did not inhibit the NPE-to-PE flux. Isoproterenol (10 microM) added to the PE side of the bilayer increased Isc by a dose-dependent 53%. Prior addition of bumetanide to the PE side blocked the increase due to isoproterenol by 37%. Isoproterenol (10 microM) stimulated the PE-to-NPE chloride flux by 75% but had no stimulatory effect on the NPE-to-PE chloride flux. 4,4'Diisothiocyanatostilbene-2,2'disulfonic acid (DIDS) inhibited Isc when added to either side of the bilayer but was more potent at low concentrations (<100 microM) when added to the NPE side and more potent at higher concentrations (>100 microM) when added to the PE side. Prior addition of 1 mM DIDS to the NPE side decreased isoproterenol stimulation of Isc by 56%. CONCLUSIONS: NaKCl cotransporters located primarily on the blood side of rabbit ciliary epithelium contribute to aqueous-negative Isc and to blood-to-aqueous chloride transport across the tissue in bicarbonate-containing medium. DIDS-inhibitable mechanisms, possibly including HCO3-Cl exchange and Cl channels, also play a role. Isoproterenol stimulation of Isc involves coordinate upregulation of PE-side NaKCl cotransport and an NPE-side DIDS-inhibitable mechanism(s).
4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
Characterization of genetic instability in radiation- and benzene-induced murine acute leukemia.
This study, using the CBA/Ca mouse as a model, compares genetic lesions associated with radiation- and benzene-induced acute leukemias. Specific types of leukemia included in the analyses are radiation-induced acute myeloid leukemia (ML), and benzene-induced lymphoblastic leukemias, lymphomas, or mix-lineage leukemias. These leukemias have histopathological characteristics similar to those seen in human acute leukemias. G-band cytogenetic analysis showed that specific deletions involving regions D-E of one copy of mouse chromosome 2 [del(2)(D-E)] were frequently associated in both radiation- and benzene-induced acute leukemias. In addition, translocations of chr2(D-E) were also observed in some cases. These results suggest an important role of chr2 (D-E) deletions and translocations in the development of radiation- and benzene-induced murine acute leukemias. Fluorescence in situ hybridization with DNA probes specific for 2(D-E), constructed in our laboratory by means of chromosomal microdissection and PCR amplification, also demonstrate 2(D-E) deletions and/or translocations in these leukemic cells. Aneuploidy of chromosomes 3, 15, 16, and Y were also frequently detected in benzene-induced leukemic cells with or without lesions on chr2. These cytogenetic findings support the previous observations that metabolites of benzene lead to spindle-fiber disruption or abnormal cytokinesis in exposed animals. In summary, genetic instabilities observed in leukemic cells isolated from mice that had developed leukemia after exposure to radiation or benzene are syntenic with those frequently detected in patients with myelodysplastic syndrome, acute ML, and acute lymphoblastic leukemia. Thus, the CBA/Ca mouse has several characteristics that make it an excellent model for the study of radiation or benzene leukemogenesis in humans.
Animals↗
Infection with multiple strains of Borrelia burgdorferi sensu stricto in patients with Lyme disease.
OBJECTIVE: To assess human skin biopsy specimens from erythema migrans lesions for the presence of infection with multiple strains of the Lyme disease spirochete, Borrelia burgdorferi. DESIGN: Skin biopsy specimens were obtained prospectively from patients with erythema migrans. To determine allelic differences and strain identification of B burgdorferi, the biopsy specimens were analyzed by cold single-strand conformation polymorphism of an amplified fragment of the outer surface protein C (ospC) gene. Further single-strand conformation polymorphism patterns of amplified ospC genes from culture isolates were compared with polymerase chain reaction products obtained directly from erythema migrans biopsy specimens. SETTING: A private dermatology office and a university medical center outpatient department. PATIENTS: Sixteen patients presenting with erythema migrans. RESULTS: Two of the 16 patients in this cohort were infected with 2 B burgdorferi sensu stricto strains, as evidenced by 2 ospC alleles in their skin biopsy results. CONCLUSION: This is the first documented description of the existence of more than a single strain of B burgdorferi sensu stricto in a human specimen.
Adult↗
1H, 13C, and 15N NMR backbone assignments of 37 kDa surface antigen OspC from Borrelia burgdorferi.
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Antigens, Bacterial↗
Genetic diversity of ospC in a local population of Borrelia burgdorferi sensu stricto.
The outer surface protein, OspC, is highly variable in Borrelia burgdorferi sensu stricto, the agent of Lyme disease. We have shown that even within a single population OspC is highly variable. The variation of ospA and ospC in the 40 infected deer ticks collected from a single site on Shelter Island, New York, was determined using PCR-SSCP. There is very strong apparent linkage disequilibrium between ospA and ospC alleles, even though they are located on separate plasmids. Thirteen discernible SSCP mobility classes for ospC were identified and the DNA sequence for each was determined. These sequences, combined with 40 GenBank sequences, allow us to define 19 major ospC groups. Sequences within a major ospC group are, on average, <1% different from each other, while sequences between major ospC groups are, on average, approximately 20% different. The tick sample contains 11 major ospC groups, GenBank contains 16 groups, with 8 groups found in both samples. Thus, the ospC variation within a local population is almost as great as the variation of a similar-sized sample of the entire species. The Ewens-Watterson-Slatkin test of allele frequency showed significant deviation from the neutral expectation, indicating balancing selection for these major ospC groups. The variation represented by major ospC groups needs to be considered if the OspC protein is to be used as a serodiagnostic antigen or a vaccine.
Alleles↗
Four clones of Borrelia burgdorferi sensu stricto cause invasive infection in humans.
Lyme disease begins at the site of a tick bite, producing a primary infection with spread of the organism to secondary sites occurring early in the course of infection. A major outer surface protein expressed by the spirochete early in infection is outer surface protein C (OspC). In Borrelia burgdorferi sensu stricto, OspC is highly variable. Based on sequence divergence, alleles of ospC can be divided into 21 major groups. To assess whether strain differences defined by ospC group are linked to invasiveness and pathogenicity, we compared the frequency distributions of major ospC groups from ticks, from the primary erythema migrans skin lesion, and from secondary sites, principally from blood and spinal fluid. The frequency distribution of ospC groups from ticks is significantly different from that from primary sites, which in turn is significantly different from that from secondary sites. The major groups A, B, I, and K had higher frequencies in the primary sites than in ticks and were the only groups found in secondary sites. We define three categories of major ospC groups: one that is common in ticks but very rarely if ever causes human disease, a second that causes only local infection at the tick bite site, and a third that causes systemic disease. The finding that all systemic B. burgdorferi sensu stricto infections are associated with four ospC groups has importance in the diagnosis, treatment, and prevention of Lyme disease.
Antigens, Bacterial↗
High-throughput transformation and plating using petristrips.
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Ampicillin↗
Bcl-2 expression identifies an early stage of myogenesis and promotes clonal expansion of muscle cells.
We show that Bcl-2 expression in skeletal muscle cells identifies an early stage of the myogenic pathway, inhibits apoptosis, and promotes clonal expansion. Bcl-2 expression was limited to a small proportion of the mononucleate cells in muscle cell cultures, ranging from approximately 1-4% of neonatal and adult mouse muscle cells to approximately 5-15% of the cells from the C2C12 muscle cell line. In rapidly growing cultures, some of the Bcl-2-positive cells coexpressed markers of early stages of myogenesis, including desmin, MyoD, and Myf-5. In contrast, Bcl-2 was not expressed in multinucleate myotubes or in those mononucleate myoblasts that expressed markers of middle or late stages of myogenesis, such as myogenin, muscle regulatory factor 4 (MRF4), and myosin. The small subset of Bcl-2-positive C2C12 cells appeared to resist staurosporine-induced apoptosis. Furthermore, though myogenic cells from genetically Bcl-2-null mice formed myotubes normally, the muscle colonies produced by cloned Bcl-2-null cells contained only about half as many cells as the colonies produced by cells from wild-type mice. This result suggests that, during clonal expansion from a muscle progenitor cell, the number of progeny obtained is greater when Bcl-2 is expressed.
Animals↗