Meta-analysis: the effect of antibiotic resistance status on the efficacy of triple and quadruple first-line therapies for Helicobacter pylori.

BACKGROUND: Information regarding the effects of drug resistance on therapies for Helicobacter pylori is limited. AIMS: To determine the effect of drug resistance on the efficacy of first-line treatment regimens for H. pylori and identify the most efficacious treatments in the presence of drug resistance. METHODS: We searched for studies using the keywords: 'Helicobacter pylori','resistance' and 'treatment' or 'therapy'. Multilevel meta-regression models were used to determine the effect of drug resistance on treatment efficacy. RESULTS: We analysed data from 93 studies with 10,178 participants. For triple therapies, clarithromycin resistance had a greater effect on treatment efficacy than nitroimidazole resistance. Metronidazole resistance reduced efficacy by 26% in triple therapies containing a nitroimidazole, tetracycline and bismuth, while efficacy was reduced by only 14% when a gastric acid inhibitor was added to the regimen. Quadruple therapies containing both clarithromycin and metronidazole were the most efficacious; >80% of H. pylori infections were consistently eradicated with these regimens. CONCLUSIONS: Drug resistance was a strong predictor of efficacy across triple therapies for the eradication of H. pylori in adults. Resistance to either clarithromycin or metronidazole, but not both simultaneously, may be overcome by using quadruple therapies, especially those containing both clarithromycin and metronidazole.

The enhancement of phototropin-induced phototropic curvature in Arabidopsis occurs via a photoreversible phytochrome A-dependent modulation of auxin responsiveness.

The induction of phototropism in etiolated (dark-grown) seedlings exposed to an unidirectional pulse or extended irradiation with low fluence rate blue light (BL) requires the action of the phototropin (nph1) BL receptor. Although cryptochromes and phytochromes are not required for phototropic induction, these photoreceptors do modulate the magnitude of curvature resulting from phototropin activation. Modulatory increases in the magnitude of phototropic curvature have been termed "enhancement." Here, we show that phototropic enhancement is primarily a phytochrome A (phyA)-dependent red/far-red-reversible low fluence response. This phyA-dependent response is genetically separable from the basal phototropin-dependent response, as demonstrated by its retention under extended irradiation conditions in the nph4 mutant background, which normally lacks the basal BL-induced response. It is interesting that the nph4 mutants fail to exhibit the basal phototropin-dependent and phyA-dependent enhancement responses under limiting light conditions. Given that NPH4 encodes a transcriptional activator, auxin response factor 7 (ARF7), we hypothesize that the ultimate target(s) of phyA action during the phototropic enhancement response is a rate-limiting ARF-containing transcriptional complex in which the constituent ARFs can vary in identity or activity depending upon the irradiation condition.

Phototropism: a "simple" physiological response modulated by multiple interacting photosensory-response pathways.

Phototropism is the process by which plants reorient growth of various organs, most notably stems, in response to lateral differences in light quantity and/or quality. The ubiquitous nature of the phototropic response in the plant kingdom implies that it provides some adaptive evolutionary advantage. Upon visual inspection it is tempting to surmise that phototropic curvatures result from a relatively simple growth response to a directional stimulus. However, detailed photophysiological, and more recently genetic and molecular, studies have demonstrated that phototropism is in fact regulated by complex interactions among several photosensory systems. At least two receptors, phototropin and a presently unidentified receptor, appear to mediate the primary photoreception of directional blue light cues in dark-grown plants. PhyB may also function as a primary receptor to detect lateral increases in far-red light in neighbor-avoidance responses of light-grown plants. Phytochromes (phyA and phyB at a minimum) also appear to function as secondary receptors to regulate adaptation processes that ultimately modulate the magnitude of curvature induced by primary photoperception. As a result of the interactions of these multiple photosensory systems plants are able to maximize the adaptive advantage of the phototropic response in ever changing light environments.

The NPH4 locus encodes the auxin response factor ARF7, a conditional regulator of differential growth in aerial Arabidopsis tissue.

Organ bending through differential growth represents a major mechanism by which plants are able to adaptively alter their morphology in response to local changes in the environment. Two plant hormones, auxin and ethylene, have been implicated as regulators of differential growth responses; however, the mechanisms by which they elicit their effects remain largely unknown. Here, we describe isolation of the NPH4 gene of Arabidopsis, which is conditionally required for differential growth responses of aerial tissues, and we report that NPH4 encodes the auxin-regulated transcriptional activator ARF7. The phenotypes of nph4 mutants, which include multiple differential growth defects associated with reduced auxin responsiveness, including impaired auxin-induced gene expression, are consistent with the predicted loss of function of a transcriptional activator, and these phenotypes indicate that auxin-dependent changes in gene transcription are prerequisite for proper organ bending responses. Although NPH4/ARF7 appears to be a major regulator of differential growth, it is not the sole regulator because phenotypes of nph4 null mutants were suppressed by application of ethylene. This latter finding illustrates the intimate connection between auxin and ethylene in the control of growth in higher plants.

NPH4, a conditional modulator of auxin-dependent differential growth responses in Arabidopsis.

Although sessile in nature, plants are able to use a number of mechanisms to modify their morphology in response to changing environmental conditions. Differential growth is one such mechanism. Despite its importance in plant development, little is known about the molecular events regulating the establishment of differential growth. Here we report analyses of the nph4 (nonphototropic hypocotyl) mutants of Arabidopsis that suggest that the NPH4 protein plays a central role in the modulation of auxin-dependent differential growth. Results from physiological studies demonstrate that NPH4 activity is conditionally required for a number of differential growth responses, including phototropism, gravitropism, phytochrome-dependent hypocotyl curvature, apical hook maintenance, and abaxial/adaxial leaf-blade expansion. The nph4 mutants exhibited auxin resistance and severely impaired auxin-dependent gene expression, indicating that the defects associated with differential growth likely arise because of altered auxin responsiveness. Moreover, the auxin signaling events mediating phototropism are genetically correlated with the abundance of the NPH4 protein.

Comparison of IgA-alpha1-antitrypsin levels in rheumatoid arthritis and seronegative oligoarthritis: complex formation is not associated with inflammation per se.

Serum complexes between IgA and alpha1-antitrypsin (IgA alpha1AT) have been found at raised levels in early rheumatoid arthritis (RA), where they appear to be associated with more erosive disease. We have now measured the levels of these complexes in the sera and synovial fluid of patients with RA and seronegative oligoarthritis to determine whether there is a relationship between complex levels and joint inflammation, and if bacterial stimulation of the mucosa is associated with complex formation in seronegative oligoarthritis. IgA-alpha1AT complexes were measured in patients with RA (n = 75) and seronegative oligoarthritis, with or without definite reactive arthritis (n = 28), using a newly developed sandwich ELISA. The results were compared with serum levels from healthy volunteers (n = 30). IgA and alpha1AT were also measured using ELISA and radial immunodiffusion (RID) techniques, respectively. IgA-alpha1AT complex levels in the sera of RA patients [mean = 25.6 arbitrary units (au)] were significantly higher (P = 0.0034) than those in patients with seronegative oligoarthritis (mean = 12.36 au) and healthy controls (mean = 8.08 au). There was no evidence for the inflamed joint being the source of IgA-alpha1AT complexes since synovial fluid levels were lower than corresponding serum levels, although higher amounts were found in RA than seronegative oligoarthritis (12.84 au vs 4.11 au, P = 0.01). Serum levels of IgA and alpha1AT were similar in RA and seronegative oligoarthritis patients, and were higher than in normals. There was a significant correlation between complex and serum IgA levels in RA (r = 0.49, P < 0.001) and seronegative oligoarthritis (r = 0.53, P < 0.001) patients, although no relationship was found with alpha1AT levels. There was no correlation with other markers of the acute-phase response (C-reactive protein, erythrocyte sedimentation rate), nor with any clinical markers. In RA patients, serum complex levels were significantly higher in seropositive than seronegative patients (30.75 vs 16.48 au, P = 0.03), and we have demonstrated that a small amount of alpha1AT may be complexed with IgA rheumatoid factor. Our data suggest that the formation of IgA-alpha1AT complexes is not associated with inflammation per se, and does not appear to be related to bacterial stimulation of the mucosal immune system in patients with seronegative oligoarthritis.

Effects of rumpshaker mutation on CNS myelin composition and structure.

Myelinated CNS tissues from homozygous/hemizygous and heterozygous jimpy rumpshaker jprsh mutant mice were examined to determine the consequences on myelin structure of this mutation in the proteolipid protein (PLP) gene. Polyacrylamide gel electrophoresis and immunoblotting of brain homogenates confirmed that there was a decrease in PLP levels on the B6C3 genetic background onto which this gene was bred. We also observed an increase in level of a protein band that could correspond to the uncharacterized 10-kDa PLP previously reported in jprsh mice on an Rb(1.3) 1Bnr background. High-performance TLC and densitometry of lipids from brain homogenate and isolated myelin revealed a decrease in content of cerebrosides and sulfatides. Electron microscopy on optic nerves revealed that normal radial component is retained in jprsh myelin, further substantiating that PLP is not a component of this junctional complex. X-ray diffraction measurements on unfixed optic nerves showed that the jprsh period is 5-10 A larger than normal. Moreover, jprsh optic nerve myelin was unstable, as evidenced by a continual increase in the period postdissection. jprsh myelin that was equilibrated at varying pH and ionic strength typically had a larger than normal period under all conditions (both swelling and compacting). Our findings thus demonstrate that the biochemical abnormalities in the jprsh mutant correlate with a wider periodicity and less stable packing of the myelin.

Therapist efficiency and clinic accessibility with the Mental Health Research Institute brief therapy model.

A health maintenance organization (HMO) mental health clinic used the Mental Research Institute (MRI) brief therapy model to achieve striking therapist efficiency and clinic accessibility. In the two-year period from January 1985 through December 1986, the clinic averaged 834 separate patients per therapist, compared with a regional average of 456 patients. The rate of hospitalization from the clinic catchment area was two thirds that of the region. This article describes the MRI approach as practiced at the clinic and discusses its applicability to community mental health centers and other mental health clinics.

Lymphocyte surface antigen L25 is a member of the integrin receptor superfamily.

Monoclonal antibody (mAb) anti-L25 identifies an antigen on the surface of human lymphocytes. This mAb immunoprecipitated three distinct polypeptides of Mr 150,000, 85,000, and 75,000 from Nonidet P-40 lysates of surface radioiodinated lymphocytes. The three polypeptides were found under both nonreducing and reducing conditions. An additional polypeptide of Mr 130,000 was detected in mAb anti-L25 immuno-precipitates when cells were lysed with CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate). Epitope localization experiments indicated that both the Mr 150,000 and 85,000 polypeptides contained antibody reactive sites. Peptide mapping studies demonstrated structural similarities in the Mr 150,000 and 85,000 components. The analysis of L25 subunits from lysates of antigen-stimulated T lymphocytes revealed a loss of the Mr 150,000 polypeptides in mAb anti-L25 immunoprecipitates. Solid phase double determinant binding assays demonstrated that L25 is similar and probably identical to lymphocyte surface antigen very late activation-4. This relationship placed L25 as a member of the integrin receptor superfamily.

Expression of Leu-19 (NKH-1) antigen on IL 2-dependent cytotoxic and non-cytotoxic T cell lines.

The Leu-19 (NKH-1) antigen is expressed on human peripheral blood NK cells and a subset of peripheral blood cytotoxic T lymphocytes that kill "NK-sensitive" tumor cell targets without major histocompatibility complex restriction. In the present study, we demonstrate that the Leu-19 (NKH-1) antigen is also expressed on most interleukin 2 (IL 2) dependent T cell lines and clones that have been maintained in long term culture. The Leu-19 (NKH-1) antigen expressed on an antigen-specific, class I directed cytotoxic T lymphocyte cell line was an approximately 200,000 to 220,000 dalton protein, similar to Leu-19 (NKH-1) protein expressed on natural killer cells and KG1a, an immature stem cell leukemia cell line. Furthermore, Leu-19 (NKH-1) was expressed on both CD4+ and CD8+ IL 2 dependent T cell clones, and was present on both cytotoxic and non-cytotoxic T cell clones. Thus expression of Leu-19 (NKH-1) antigen on cultured cell lines does not directly correlate with cytotoxic function, antigenic specificity, or cell lineage.

Monoclonal antibodies that distinguish between class II antigens (HLA-DP, DQ, and DR) in 14 haplotypes.

The specificity of three commonly used monoclonal antibodies (MoAbs) reacting with human class II histocompatibility antigens, was analyzed to determine whether these MoAbs would distinguish between HLA-DP, DQ, and DR in a large number of haplotypes. The reactivity of these MoAbs (L243, Anti-Leu 10, and B7/21) was compared by serial immunoprecipitation of class II antigens from 11 B-cell lines. The cell lines examined expressed a total of five DP, three DQ, and nine DR types, which together represent most of the well-defined class II specificities. This is the first demonstration that one of these antibodies, B7/21. binds to at least five DP specificities, and does not bind to DR or DQ molecules as defined by reactivity with the two other MoAbs. Within the scope of these experiments, the B7/21 antibody was shown to react with a monomorphic DP determinant. A variant clone of the B7/21 hybridoma was isolated that secretes IgG1 antibody with the same specificity as the original IgG3 antibody. The two other antibodies studied have been previously shown to react with DR molecules (L243) or DQ molecules (Anti-Leu 10). Here, their lack of cross-reaction with DP molecules is demonstrated. Thus, each of the three MoAbs reacts exclusively with a distinct class II molecule in all haplotypes studied, and therefore should be useful for comparing the independent expression and function of DP, DQ, and DR molecules.

Identification and characterization of two novel lymphocyte function-associated antigens, L24 and L25.

We describe the function and cell distribution of two novel cell surface antigens, L24 and L25. These antigens are broadly distributed on human lymphocytes. Monoclonal antibodies specific for these molecules block lysis by Class I- and II-specific cytotoxic T lymphocytes, but do not affect any other T cell functions tested. Anti-L24 antibody immunoprecipitates a molecule composed of two disulfide-linked monomers of 140 kd each. Anti-L25 antibody immunoprecipitates three proteins of 150, 85, and 75 kd. The study of these and other function associated molecules may provide insight into mechanisms of cytotoxic T lymphocyte recognition and/or function.

S-phase detection with an antibody to bromodeoxyuridine. Role of DNase pretreatment.

We have previously described a monoclonal antibody (BU-1) to 5-bromo-2-deoxyuridine (BrdUrd) that is useful for measurement of cell cycle S-phase. BU-1 hybridoma supernatant reacted with incorporated BrdUrd after the cells had been ethanol fixed; without a requirement for acid or base denaturation. We have found that this reactivity is lost if purified antibody is used, if the culture supernatants are heated, or if a mycoplasma-free hybridoma line is isolated. The supernatant contained endogenous DNase activity that was a result of mycoplasma infection of the cell line. This DNase activity was required for staining the cells with BU-1 in the absence of other denaturation steps. The endogenous DNase could be substituted for by the addition of bovine pancreatic DNase I. The disruption of the double stranded DNA structure with an enzyme rather than with harsh chemical or heat treatments does not affect protein structure or cellular morphology and allows the detection of incorporated BrdUrd of morphologic or antigenic cell subsets. DNase pre-treatment may also be useful for detection of other 'hidden' DNA antigens.

Evaluation of diallate and triallate herbicides for genotoxic effects in a battery of in vitro and short-term in vivo tests.

Commercial-grade preparations of two thiocarbamate herbicides, diallate and triallate, were evaluated for their mutagenic potential in a battery of short-term bioassays. All in vitro bioassays were performed with and without mammalian metabolic activation, and all such tests were repeated after an interval of at least 1 week. Diallate and triallate were tested in the Salmonella/microsome assay over dose ranges of 0.59 to 118.0 micrograms/plate and 6.37 to 1273 micrograms/plate, respectively. Both diallate and triallate gave positive results in S. typhimurium strains TA1535, TA98, and TA100 only in the presence of a rat-liver metabolic activation system. In Saccharomyces cerevisiae strain D7, diallate was tested at concentrations from 1.18 to 29.50 micrograms/ml, and triallate was tested at 0.955 to 9.548 micrograms/ml. Both diallate and triallate gave negative results for mitotic gene conversion, mitotic crossing-over, and reverse mutation. In the mouse lymphoma L5178Y TK+/- assay, diallate was tested at concentrations ranging from 1 to 72 micrograms/ml, and triallate was tested at 0.5 to 60 micrograms/ml. Both herbicides produced mutagenic responses in the mouse lymphoma assay in the presence of metabolic activation. In the Drosophila sex-linked recessive lethal test, flies were exposed to 0.0004% diallate and 0.001% triallate. In this assay, diallate was considered mutagenic, whereas triallate did not produce a detectable mutagenic response.

Properties of a mutant Escherichia coli phosphoenolpyruvate carboxylase deficient in coregulation by intermediary metabolites.

Phosphoenolpyruvate carboxylase of Escherichia coli is activated by three different mechanisms: contiguous by acetyl coenzyme A, precursor by fructose 1,6-bisphosphate, and compensatory feedback by cytidine 5'-diphosphate (CDP). Even though each activator can interact independently with the enzyme, synergistic effects are observed with some combinations, namely, fructose 1,6-bisphosphate or CDP (coregulators), with acetyl coenzyme A. A mutant was isolated that has a phosphoenolpyruvate carboxylase which is refractory to activation by fructose, 1,6-bisphosphate and CDP. The mutant enzyme was shown to be active primarily as the dimer and to lack cooperativity in substrate binding. The binding of acetyl coenzyme A and substrate, however, was essentially the same as that of the wild-type enzyme. The mutant cells grew extremely slowly on glucose alone as the sole carbon source. The only defect in the mutant appeared to be the inability of this enzyme to be activated by the coregulators. These data are consistent with the thesis that coregulation by fructose 1,6-bisphosphate or CDP is an essential requirement for the activation in vivo of this enzyme.

Phycobilisomes in Anacystis nidulans.

Phycobilisomes were demonstrated in Anacystis nidulans by chemical and morphological studies on cells grown in red light. These cells showed a marked reduction in the chlorophyll-phycocyanin ratio owing to a decreased chlorophyll content. Granular structures of approximately 35 nm were observed throughout red light-grown cells, but were most distinct in the peripheral region. The presence of phycobilisomes in cells grown in red light as well as in cells grown in white light is supported by experiments in which glutaraldehyde was used to stabilize the attachment between the phycobiliprotein and the thylakoids, allowing the isolation of both in the same fraction by sucrose density gradient centrifugation.

Kinetics of single-layer graphite oxidation: evaluation by electron microscopy.

Etch-decoration reveals that the rate of removal of carbon atoms exposed at monolayer steps on graphite surfaces is very different from the rate of removal, under identical conditions, at multilayer steps. At 1113 degrees K and a pressure of 1.33 newtons per square meter of oxygen, the rate of oxidation (along the layer planes) is less by a factor of nearly 100 than that at multilayer steps.