Signaling mismatch repair: the mechanics of an adenosine-nucleotide molecular switch.
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Adenosine↗
Biomedical subjects
T Wilson
Publications and source records attributed to T Wilson.
Analysis of a bi-state, multi-district, school-based hepatitis B immunization program.
A descriptive correlational research design assessed factors influencing participation and completion rates, and to determine vaccine administration costs, in a school-based Hepatitis B vaccination program. Of 18,046 students in public and private schools in the metropolitan Kansas City, Mo., area, 12,986 (73.4%) participated with approximately 75% of these students completing the vaccine series. Larger schools reported decreased participation and completion rates. Both rates were highest in schools providing educational interventions. Schools with a large population of commercially insured students reported low participation rates (65%), but high completion rates (85%). Schools with a high number of Medicaid-eligible students had high participation rates (97%), but low completion rates (67%). The vaccine cost $5.06 per dose to administer.
Adolescent↗
Development and clinical evaluation of a recombinant-antigen-based cytomegalovirus immunoglobulin M automated immunoassay using the Abbott AxSYM analyzer.
A new microparticle enzyme immunoassay (MEIA), the Cytomegalovirus (CMV) Immunoglobulin M (IgM) test, was developed on the Abbott AxSYM analyzer. This test uses recombinant CMV antigens derived from portions of four structural and nonstructural proteins of CMV: pUL32 (pp150), pUL44 (pp52), pUL83 (pp65), and pUL80a (pp38). A total of 1, 608 specimens from random volunteer blood donors (n = 300), pregnant women (n = 1,118), transplant recipients (n = 6), and patients with various clinical conditions and disease states (n = 184) were tested during development and evaluation of this new assay. In a preliminary clinical evaluation we tested specimens collected prospectively from pregnant women (n = 799) and selected CMV IgM-positive archived specimens from pregnant women (n = 39). The results from the new CMV IgM immunoassay were compared to the results of a consensus interpretation of the results obtained with three commercial CMV IgM immunoassays. The results for specimens with discordant results were resolved by a CMV IgM immunoblot assay. The relative sensitivity, specificity, and agreement for the AxSYM CMV IgM assay were 94.29, 96.28, and 96.19%, respectively, and the resolved sensitivity, specificity, and agreement were 95.83, 97.47, and 97.37%, respectively. We also tested serial specimens from women who experienced seroconversion or a recent CMV infection during gestation (n = 17) and potentially cross-reactive specimens negative for CMV IgM antibody by the consensus tests (n = 184). The AxSYM CMV IgM assay was very sensitive for the detection of CMV IgM during primary CMV infection, as shown by the detection of CMV IgM at the same time as or just prior to the detection of CMV IgG. Specimens from individuals with lupus (n = 16) or parvovirus B19 infection (n = 6) or specimens containing hyper IgM (n = 9), hyper IgG (n = 8), or rheumatoid factor (n = 55) did not cross-react with the AxSYM assay. One specimen each from individuals infected with Epstein-Barr virus (n = 26), measles virus (n = 10), herpes simplex virus (n = 12), or varicella-zoster virus (n = 13) infection, one specimen from an influenza vaccinee (n = 14), and one specimen containing antinuclear antibody cross-reacted with the assay. The overall rate of cross-reactivity of the specimens with the assay was 3.3% (6 of 184). The AxSYM CMV IgM assay is a sensitive and specific assay for the detection of CMV-specific IgM.
Antibodies, Viral↗
The Expert Patient: a proactive role for DNs?
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Chronic Disease↗
New modal wave-front sensor: a theoretical analysis
We present a new design of a modal wave-front sensor capable of measuring directly the Zernike components of an aberrated wave front. The sensor shows good linearity for small aberration amplitudes and is particularly suitable for integration in a closed-loop adaptive system. We introduce a sensitivity matrix and show that it is sparse, and we derive conditions specifying which elements are necessarily zero. The sensor may be temporally or spatially multiplexed, the former using a reconfigurable optical element, the latter using a numerically optimized binary optical element. Different optimization schemes are discussed, and their performance is compared.
Journal Article↗
Effects of bleeding nonanesthetized wild rodents on handling mortality and subsequent recapture.
Handling mortality and recapture rates of wild rodents that were bled from the retroorbital capillary plexus without anesthesia were assessed. In 9,670 captures of seven species of rodents from 1994 through 1998, we found no difference in handling mortality in bled mice compared to those from trapping grids where mice were not bled. Recapture rates of rodents on control (non-bleeding grids) and rodents on bleeding grids was not significantly different for any species. We conclude that bleeding in the absence of anesthesia does not affect immediate mortality or subsequent recapture.
Anesthesia↗
Synthesis and pharmacological evaluations of N-(substituted benzoylamino)-5-carbethoxymethyl-1,2,3,6-tetrahydropyridines as potential antiinflammatory agents.
In a continuing effort to enhance antiinflammatory activities, a series of 1,2,3,6-tetrahydropyridines, 4-tert butyl (9a), 4-methoxy (9b), 2-fluoro (9c), 3-chloro (9d) and 3,4-dichloro (9e) benzoylamino-5-carbethoxymethyl-1,2,3,6-tetrahydropyridines, were synthesized and evaluated for their antiinflammatory activities. Antiinflammatory activities were screened in animal models employing carrageenan induced paw-edema assay on the male Sprague-Dawley rat. Relative potencies for carrageenan induced paw-edema assay were 1, 0.07, > 0.03, 0.14, 0.4 and 0.12 for indomethacin (IC50 = 3 mg/kg), 9a, 9b, 9c, 9d and 9e, respectively. These novel tetrahydropyridines were assessed for nonsteroidal antiinflammatory drug-mediated inhibition of nitric oxide generation in RAW 264.7 macrophage cell line using Griess' reagent. Relative potencies for inhibition of nitric oxide generation by macrophages stimulated with lipopolysaccharide (1 microgram/ml) were 1, 0.48, 0.44, 0.43, 0.45 and 0.45 for indomethacin (IC50 = 0.434 mM), 9a, 9b, 9c, 9d and 9e, respectively. The results show that novel tetrahydropyridines have moderate antiinflammatory activities and that they inhibit nitric oxide production by inhibiting inducible nitric oxide synthase.
Animals↗
Identification of ammonium ion and 2,6-bis(omega-aminobutyl)- 3, 5-diiminopiperazine as endogenous factors that account for the "burst" of sphingosine upon changing the medium of J774 cells in culture.
Cells in culture often undergo a "burst" of free sphingosine, sphingosine 1-phosphate, ceramide, and other bioactive lipids upon removal of "conditioned" medium, and at least one lipid signaling pathway (protein kinase C) has been shown to be affected by these changes (Smith, E. R. & Merrill A. H., Jr. (1995) J. Biol. Chem. 270, 18749-18758; Smith, E. R., Jones, P. L., Boss, J. M. & Merrill, A. H., Jr. (1997) J. Biol. Chem. 272, 5640-5646). Whereas increases in sphinganine and dihydroceramide are responses to provision of precursors for sphingolipid biosynthesis de novo in the new medium, the sphingosine burst is due to sphingolipid turnover upon removal of suppressive factor(s) in conditioned medium. This study describes the purification and characterization of these suppressive factors. Conditioned medium from J774 cells was fractionated into two components that suppress the burst as follows: ammonium ion, which reaches 2-3 mM within 48 h of cell culture; and a low molecular weight, cationic compound that has been assigned the structure 2, 6-bis(omega-aminobutyl)-3,5-diimino-piperazine (for which we suggest the name "batrachamine" based on its appearance) by (1)H and (13)C NMR, Fourier transform infrared spectroscopy, and mass spectrometric analyses. The physiological significance of these compounds as suppressors of sphingolipid metabolism is unclear; however, ammonium ion is a by-product of amino acid catabolism and reaches high concentrations in some tissues. Batrachamine is even more intriguing because this is, as far as we are aware, the first report of a naturally occurring compound of this structural type. Considering the many cell functions that are affected by sphingoid bases and their derivatives, the effects of NH(4) and batrachamine on sphingolipid metabolism may have important implications for cell regulation.
Ammonium Chloride↗
Treatment of toenail onychomycosis. Prescribing terbinafine to every patient with the condition would be expensive.
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Antifungal Agents↗
Dissociation of mismatch recognition and ATPase activity by hMSH2-hMSH3.
MSH2-MSH3 directs the repair of insertion/deletion loops of up to 13 nucleotides in vivo and in vitro. To examine the biochemical basis of this repair specificity, we characterized the mispair binding and ATPase activity of hMSH2-hMSH3. The ATPase was found to be regulated by a mismatch-stimulated ADP --> ATP exchange, which induces a conformational transition by the protein complex. We demonstrated strong binding of hMSH2-hMSH3 to an insertion/deletion loop containing 24 nucleotides that is incapable of provoking ADP --> ATP exchange, suggesting that mismatch recognition appears to be necessary but not sufficient to induce the intrinsic ATPase. These studies support the idea that hMSH2-hMSH3 functions as an adenosine nucleotide-regulated molecular switch that must be activated by mismatched nucleotides for classical mismatch repair to occur.
Adenosine Diphosphate↗
Apoptosis induced by overexpression of hMSH2 or hMLH1.
Mutations of the mismatch repair genes hMSH2 and hMLH1 have been found in a high proportion of individuals with hereditary nonpolyposis colon cancer (HNPCC), establishing the link between mismatch repair and cancer. Tumor cell lines that are deficient in mismatch repair develop a mutator phenotype that appears to drive the accumulation of mutations required for tumor development. However, mutations of other mismatch repair genes such as hPMS2 can lead to a mutator phenotype, although inherited mutations of these genes are rare in HNPCC families. Here, we show that overexpression of hMSH2 or hMLH1 but not of hMSH3, hMSH6, or hPMS2 induces apoptosis in either repair-proficient or -deficient cells. Furthermore, primary mouse embryo fibroblasts derived from Msh2-deficient mice lose their ability to undergo apoptosis after treatment with N-methyl-N'-nitro-N-nitrosoguanidine. These results suggest that the mismatch repair proteins hMSH2 and hMLH1 may be components of a pathway that influences apoptosis. We consider the possibility that loss of apoptosis as a result of hMSH2 or hMLH1 deficiency may be an additional factor in cancer predisposition in HNPCC.
Adaptor Proteins, Signal Transducing↗
hMSH2-hMSH6 forms a hydrolysis-independent sliding clamp on mismatched DNA.
Mismatch recognition by the human MutS homologs hMSH2-hMSH6 is regulated by adenosine nucleotide binding, supporting the hypothesis that it functions as a molecular switch. Here we show that ATP-induced release of hMSH2-hMSH6 from mismatched DNA is prevented if the ends are blocked or if the DNA is circular. We demonstrate that mismmatched DNA provokes ADP-->ATP exchange, resulting in a discernible conformational transition that converts hMSH2-hMSH6 into a sliding clamp capable of hydrolysis-independent diffusion along the DNA backbone. Our results support a model for bidirectional mismatch repair in which stochastic loading of multiple ATP-bound hMSH2-hMSH6 sliding clamps onto mismatch-containing DNA leads to activation of the repair machinery and/or other signaling effectors similar to G protein switches.
Adenosine Triphosphatases↗
A method for characterizing longitudinal chromatic aberration of microscope objectives using a confocal optical system
We describe a novel method of characterizing the longitudinal chromatic aberration of microscope objectives by recording a series of axial responses as a function of wavelength as a plane reflector is scanned through the focal region of a confocal microscope. Measurements are presented for a variety of objectives with differing degrees of correction. The use of the chromatic focal shift to measure surface profiles is also discussed.
Journal Article↗
A regional registration technique for automated interval change analysis of breast lesions on mammograms.
Analysis of interval change is a useful technique for detection of abnormalities in mammographic interpretation. Interval change analysis is routinely used by radiologists and its importance is well-established in clinical practice. As a first step to develop a computerized method for interval change analysis on mammograms, we are developing an automated regional registration technique to identify corresponding lesions on temporal pairs of mammograms. In this technique, the breast is first segmented from the background on the current and previous mammograms. The breast edges are then aligned using a global alignment procedure based on the mutual information between the breast regions in the two images. Using the nipple location and the breast centroid estimated independently on both mammograms, a polar coordinate system is defined for each image. The polar coordinate of the centroid of a lesion detected on the most recent mammogram is used to obtain an initial estimate of its location on the previous mammogram and to define a fan-shaped search region. A search for a matching structure to the lesion is then performed in the fan-shaped region on the previous mammogram to obtain a final estimate of its location. In this study, a quantitative evaluation of registration accuracy has been performed with a data set of 74 temporal pairs of mammograms and ground-truth correspondence information provided by an experienced radiologist. The most recent mammogram of each temporal pair exhibited a biopsy-proven mass. We have investigated the usefulness of correlation and mutual information as search criteria for determining corresponding regions on mammograms for the biopsy-proven masses. In 85% of the cases (63/74 temporal pairs) the region on the previous mammogram that corresponded to the mass on the current mammogram was correctly identified. The region centroid identified by the registration technique had an average distance of 2.8+/-1.9 mm from the centroid of the radiologist-identified region. These results indicate that our new registration technique may be useful for establishing correspondence between structures on current and previous mammograms. Once such a correspondence is established an interval change analysis could be performed to aid in both detection as well as classification of abnormal breast densities.
Breast Neoplasms↗
Metabolic studies on BMS-200475, a new antiviral compound active against hepatitis B virus.
BMS-200475 was recently shown to have potent antiviral activity against hepatitis B virus (50% effective concentration = 3.7 nM; 50% cytotoxic concentration = 30 microM). In metabolic studies in both HepG2 and hepatitis B virus-transfected 2.2.15 human hepatoma cell lines, the metabolism was similar, the primary products being the di- and triphosphates. The accumulation of triphosphate was rapid and detectable down to a 5 nM concentration of added drug. When cells were labeled at 25 microM, the intracellular triphosphate concentration attained 30 pmol/10(6) cells ( approximately 30 microM). The intracellular half-life of the triphosphate was about 15 h. Compared with five other nucleoside analogs of medical interest (lamivudine, penciclovir, ganciclovir, acyclovir, and lobucavir), BMS-200475 was most efficiently phosphorylated to the triphosphate in HepG2 cells.
Antiviral Agents↗
Immune responses induced in cattle by virulent and attenuated Mycobacterium bovis strains: correlation of delayed-type hypersensitivity with ability of strains to grow in macrophages.
Comparison of immune responses induced in cattle by virulent and attenuated strains of Mycobacterium bovis will assist in identifying responses associated with resistance or susceptibility to disease. Four strains of M. bovis, one which is virulent in guinea pigs (WAg201) and three which are attenuated in guinea pigs (an isoniazid-resistant strain [WAg405], ATCC 35721, and BCG) were compared for their abilities to induce immune responses in cattle and to grow in bovine lung alveolar macrophage cultures. Extensive macroscopic lesions were found only in cattle inoculated with the virulent M. bovis strain. Strong antibody responses to M. bovis culture filtrate, as well as persistently high levels of gamma interferon and interleukin-2 released from purified protein derivative (PPD)-stimulated peripheral blood lymphocyte cultures, were observed in the cattle inoculated with the virulent strain compared to those inoculated with the attenuated strains. All cattle inoculated with the virulent strain or two of the attenuated strains (WAg405 and ATCC 35721) elicited strong delayed-type hypersensitivity responses to PPD in skin tests, while animals inoculated with BCG induced only a weak response. The three strains which produced strong skin test responses proliferated well in bovine alveolar macrophages and induced high levels of proinflammatory cytokine mRNAs compared to BCG. Our study showed that skin test responsiveness to PPD correlated with the ability of the strains to grow in alveolar macrophages rather than to their pathogenicity in cattle.
Animals↗
Vaccination of guinea pigs with nutritionally impaired avirulent mutants of Mycobacterium bovis protects against tuberculosis.
Four nutritionally impaired strains of Mycobacterium bovis produced by illegitimate recombination were tested for their ability to protect guinea pigs against intratracheal challenge with virulent M. bovis. All four strains and M. bovis BCG induced significant levels of protection as measured by the reduced spread of infection to the spleen and liver. In animals vaccinated with BCG or two of the other strains, the bacterial counts from the lungs were significantly lower than those of the nonvaccinated animals.
Animals↗
Physical and functional interactions between the herpes simplex virus UL15 and UL28 DNA cleavage and packaging proteins.
Herpes simplex virus (HSV) DNA is cleaved from concatemers and packaged into capsids in infected cell nuclei. This process requires seven viral proteins, including UL15 and UL28. UL15 expressed alone displays a nuclear localization, while UL28 remains cytoplasmic. Coexpression with UL15 enables UL28 to enter nuclei, suggesting an interaction between the two proteins. Additionally, UL28 copurified with UL15 from HSV-infected cells after ion-exchange and DNA affinity chromatography, and the complex sedimented as a 1:1 heterodimer upon sucrose gradient centrifugation. These findings are evidence of a physical interaction of UL15 and UL28 and a functional role for UL15 in directing UL28 to the nucleus.
Animals↗