[Survey of Helicobacter pylori levofloxacin and clarithromycin resistance rates and drug resistance genes in Ningxia, 2020-2022]

Objective: To explore the rate of Helicobacter pylori (Hp) resistance to levofloxacin and clarithromycin and the common mutation patterns of resistance genes in Ningxia, and to assess the concordance between phenotypic resistance and genotypic resistance. Methods: Cross-sectional study. Patients diagnosed with Hp infection in 14 hospitals in Ningxia region from February 2020 to May 2022 were retrospectively selected. Hp strains were isolated from gastric biopsy specimens of Hp-infected patients and subjected to phenotypic drug sensitivity testing and detection of resistance genes to analyze the rate of Hp resistance to levofloxacin and clarithromycin and the common mutation patterns of resistance genes in Ningxia region; and the concordance rate and Kappa concordance test were used to assess the concordance between phenotypic resistance and genotypic resistance. Results: A total of 1 942 Hp strains were isolated and cultured, and among the infections, 1 069 cases (55.0%) were male and 873 cases (45.0%) were female, aged (50.0±12.5) years (15-86 years). The rates of Hp resistance to levofloxacin and clarithromycin in Ningxia were 42.1% (818/1 942) and 40.1% (779/1 942), respectively, and the rate of dual resistance to both was 22.8% (443/1 942). The rate of resistance to levofloxacin and clarithromycin of Hp strains from female patients was higher than in male patients (levofloxacin: 50.4%(440/873) vs 35.4%(378/1 069); clarithromycin: 44.4%(388/873) vs 36.6%(391/1 069), both P<0.001). Among the GyrA gene mutations associated with levofloxacin resistance, the differences in mutation rate of amino acid at positions 87 and 91 were statistically significant in both drug-resistant and sensitive strains(both P<0.001), except for Asn87Thr. Hp strains were statistically significant for levofloxacin (Kappa=0.834, P<0.001) and clarithromycin (Kappa=0.829, P<0.001) had good concordance in resistance at the phenotypic and genotypic levels. Conclusion: The resistance of Hp to levofloxacin and clarithromycin in Ningxia region is severe, and there is good consistency between genotypic and phenotypic resistance.

A single F153Sβ3 mutation causes constitutive integrin αIIbβ3 activation in a variant form of Glanzmann thrombasthenia

This report identifies a novel variant form of the inherited bleeding disorder Glanzmann thrombasthenia, exhibiting only mild bleeding in a physically active individual. The platelets cannot aggregate ex vivo with physiologic agonists of activation, although microfluidic analysis with whole blood displays moderate ex vivo platelet adhesion and aggregation consistent with mild bleeding. Immunocytometry shows reduced expression of αIIbβ3 on quiescent platelets that spontaneously bind/store fibrinogen, and activation-dependent antibodies (ligand-induced binding site-319.4 and PAC-1) report β3 extension suggesting an intrinsic activation phenotype. Genetic analysis reveals a single F153Sβ3 substitution within the βI-domain from a heterozygous T556C nucleotide substitution of ITGB3 exon 4 in conjunction with a previously reported IVS5(+1)G>A splice site mutation with undetectable platelet messenger RNA accounting for hemizygous expression of S153β3. F153 is completely conserved among β3 of several species and all human β-integrin subunits suggesting that it may play a vital role in integrin structure/function. Mutagenesis of αIIb-F153Sβ3 also displays reduced levels of a constitutively activated αIIb-S153β3 on HEK293T cells. The overall structural analysis suggests that a bulky aromatic, nonpolar amino acid (F,W)153β3 is critical for maintaining the resting conformation of α2- and α1-helices of the βI-domain because small amino acid substitutions (S,A) facilitate an unhindered inward movement of the α2- and α1-helices of the βI-domain toward the constitutively active αIIbβ3 conformation, while a bulky aromatic, polar amino acid (Y) hinders such movements and restrains αIIbβ3 activation. The data collectively demonstrate that disruption of F153β3 can significantly alter normal integrin/platelet function, although reduced expression of αIIb-S153β3 may be compensated by a hyperactive conformation that promotes viable hemostasis.

C560Rβ3 caused platelet integrin αII b β3 to bind fibrinogen continuously, but resulted in a severe bleeding syndrome and increased murine mortality

BACKGROUND AND OBJECTIVES

β(3)-Deficient megakaryocytes were modified by human β(3)-lentivirus transduction and transplantation to express sufficient levels of a C560Rβ(3) amino acid substitution, for investigation of how an activated αII b β(3) conformation affects platelets in vivo in mice.

PATIENT/METHODS

As in our previous report of an R560β(3) mutation in a patient with Glanzmann thrombasthenia, R560β(3) murine platelets spontaneously bound antibody that only recognizes activated αII b β3 bound to its ligand, fibrinogen.

RESULTS

With this murine model, we showed that αII b -R560β3 mutation-mediated continuous binding of fibrinogen occurred in the absence of P-selectin surface expression, indicating that the integrin was in an active conformation, although the platelets circulated in a quiescent manner. Remarkably, only 35% of R560β(3) 'mutant' mice survived for 6 months after transplantation, whereas 87% of C560β(3) 'wild-type' mice remained alive. Pathologic examination revealed that R560β(3) mice had enlarged spleens with extramedullary hematopoiesis and increased hemosiderin, indicating hemorrhage. R560β(3) megakaryocytes and platelets showed abnormal morphology and irregular granule distribution. Interestingly, R560β(3) washed platelets could aggregate upon simultaneous addition of fibrinogen and physiologic agonists, but aggregation failed when platelets were exposed to fibrinogen before activation in vitro and in vivo.

CONCLUSIONS

The results demonstrate that continuous occupancy of αIIb β3 with fibrinogen disrupts platelet structure and function, leading to hemorrhagic death consistent with Glanzmann thrombasthenia rather than a thrombotic state.

Therapeutic expression of the platelet-specific integrin, alphaIIbbeta3, in a murine model for Glanzmann thrombasthenia

Integrins mediate the adhesion of cells to each other and to the extracellular matrix during development, immunity, metastasis, thrombosis, and wound healing. Molecular defects in either the alpha- or beta-subunit can disrupt integrin synthesis, assembly, and/or binding to adhesive ligands. This is exemplified by the bleeding disorder, Glanzmann thrombasthenia (GT), where abnormalities of the platelet-specific integrin, alphaIIbbeta3, prevent platelet aggregation following vascular injury. We previously used a retrovirus vector containing a cDNA cassette encoding human integrin beta3 to restore integrin alphaIIbbeta3 on the surface of megakaryocytes derived from peripheral blood stem cells of GT patients. In the present study, bone marrow from beta3-deficient (beta3-/-) mice was transduced with the ITGbeta3-cassette to investigate whether the platelet progeny could establish hemostasis in vivo. A lentivirus transfer vector equipped with the human ITGA2B gene promoter confined transgene expression to the platelet lineage. Human beta3 formed a stable complex with murine alphaIIb, effectively restoring platelet function. Mice expressing significant levels of alphaIIbbeta3 on circulating platelets exhibited improved bleeding times. Intravenous immunoglobulin effectively diminished platelet clearance in animals that developed an antibody response to alphaIIbbeta3. These results indicate the feasibility of targeting platelets with genetic therapies for better management of patients with inherited bleeding disorders.

Single-chain antibody fragments derived from a human synthetic phage-display library bind thrombospondin and inhibit sickle cell adhesion

The enhanced adhesion of sickle red blood cells (RBCs) to the vascular endothelium and subendothelial matrix likely plays a significant role in the pathogenesis of vaso-occlusion in sickle cell disease. Sickle RBCs have enhanced adhesion to the plasma and extracellular matrix protein thrombospondin-1 (TSP) under conditions of flow in vitro. In this study, we sought to develop antibodies that bind TSP from a highly diverse library of human single-chain Fv fragments (scFvs) displayed on filamentous phage. Following 3 rounds of phage selection of increasing stringency 6 unique scFvs that bound purified TSP by enzyme-linked immunosorbent assay were isolated. Using an in vitro flow adhesion assay, 3 of the 6 isolated scFvs inhibited the adhesion of sickle RBCs to immobilized TSP by more than 40% compared with control scFvs (P <.001). Furthermore, scFv TSP-A10 partially inhibited sickle RBC adhesion to activated endothelial cells (P <.005). Using TSP proteolytic fragments to map the binding site, we showed that 2 of the inhibitory scFvs bound an epitope in the calcium-binding domain or proximal cell-binding domain of TSP, providing evidence for the role of these domains in the adhesion of sickle RBCs to TSP. In summary, we have isolated a panel of scFvs that specifically bind to TSP and differentially inhibit sickle RBC adhesion to surface-bound TSP under flow conditions. These scFvs will be useful reagents for investigating the role of the calcium and cell-binding domains of TSP in sickle RBC adhesion.

[A study on the effect of rare earth metal ions on fluorescence spectra of the tryptophan using fluorescence spectroscopy]

Rare earth metal ions and tryptophan form ion-association complex in basic medium. The complex causes fluorescence quenching of tryptophan. Fluorescence emission of tryptophan and quenching caused by rare earth metal ions both reach a climax in H3BO4-HAc-H3PO4-NaOH at pH 10 to 11, and all rare earth metal ions have the approximate effects on fluorescence quenching of tryptophan. The molecular mode of complex of rare earth metal ions and tryptophan has been founded and mechanism of fluorescence quenching has been studied in this paper.

Spectroscopic study on the photoinduced reaction of fullerene C60 with aliphatic amines and its dynamics--strong short wavelength fluorescence from the adducts

The photoinduced electron donor acceptor interactions of C60 with eight kinds of aliphatic amines, namely dicthylamine (DEA), triethylamine (TEA), tri-n-amylamine (TAA), propylethylamine (PPA), n-butylamine (BTA), n-heptylamine (HPA) and dodecylamine (DDA) and ethylenediamine (EDA) are reported by a comprehensive spectroscopic study. Experiments show that there is a good discipline with different structure and the length of n-alkyl group both in their ground and excited states. At the same time, a slow reaction takes place between C60 and various amines with a gradual increase in the concentration of various aliphatic amines or the standing of solution, which can be dramatically catalyzed by UV-radiation. The final products can all emit a strong fluorescence at the relatively shorter wavelength around 519 nm. On this basis, the dynamic properties of C60/aphaliticamines including the enthalpy of activation (deltaH++et) and entropy activation (deltaS++et), together with all sorts of influence factors are firstly investigated in this work. The possible reaction mechanisms are explored, also.

[Study on the direct determination of auxins by gas chromatography]

A method for the direct determination of auxins, indole acetic acid (IAA), indole-butyric acid (IBA) and naphthylacetic acid (NAA), by gas chromatography with wide-bore capillary column is described. The gas chromatographic conditions were as follows: HP-1 capillary column, 5 m x 0.53 mm i.d., 2.65 microns film, the column temperature 180 degrees C, the temperature of injector 250 degrees C, the temperature of FID detector 260 degrees C, carrier gas: N2 20 mL/min and dibutyl phthalate was used as internal standard. All components and internal standard were separated in 3 min. The relative standard deviations were from 0.61% to 1.14%. The method is simple, rapid, sensitive, good reproducible and satisfactory.

[Separation and determination of three plant internal hormones by gas chromatography]

A method for the simultaneous separation and determination of three plant internal hormones indole acetic acid (IAA), abscisic acid(ABA) and gibberellic acid(GA) in plant by gas chromatography with wide-bore capillary column is described. The gas chromatographic conditions were as follows: FID detector; HP-1 capillary column, 5 m x 0.53 mm x 2.65 microns film; the column temperature, 220 degrees C; the injector temperature, 250 degrees C; the detector temperature, 280 degrees C, carrier gas, 3.5 mL/min N2; internal standard n-docosane. All components and internal standard were separated in 8 min. The detection limit of IAA, ABA and GA were 0.16, 0.08 and 0.48 mg/L respectively. The relative standard deviations were 2.2%, 1.7% and 2.8% respectively. The linear range were 0.16-80 mg/L(r = 0.9986), 0.08-40 mg/L (r = 0.9993) and 0.48-240 mg/L (r = 0.9991) respectively. The average recoveries were (88.4 +/- 2.4%)%, (92.2 +/- 1.2)% and (91.8 +/- 1.8)% respectively. The method is simple, rapid, sensitive and reproducible.

[Determination of alkaloids in pericarpium papaveris by gas chromatography with wide bore capillary column]

A method for the simultaneous determination of codeine, morphine, thebaine, papaverine and narcotine in pericarpium papaveris by gas chromatography with wide bore capillary column is described. The major components in pericarpium papaveris were extracted with methanol and chloroform by supersonic extraction and evaporation. The residue was dissolved in methanol. The resulting solution was used for analysis. The conditions for determination were: FID detector, HP-1 capillary column, 5 m x 0.53 mm x 2.65 microns film, column temperature 260 degrees C, The method requires 10 minutes for the whole analysis. The average recoveries of codeine, morphine, thebaine, papaverine and narcotine in the sample were 94.0%, 96.5%, 93.8%, 91.0% and 91.4% respectively. The relative standard deviations were from 0.92% to 2.75%. The advantages of this method are simple, rapid, accurate and sensitive.