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Abstract Background Dental anxiety is associated with negative experiences of dental treatment and dental-visiting behavior. The Modified Dental Anxiety Scale (MDAS) is widely used for assessing dental anxiety. The study aims to establish the psychometric properties of a Chinese version of the MDAS based on the Taiwan sample (i.e., T-MDAS). Methods The T-MDAS and dental-visiting behavior and experience were assessed for 402 adult subjects recruited from community and clinical sites. The following psychometric properties were assessed: (a) internal consistency, (b) temporal stability, (c) criterion-related validity (i.e., the association with the score of Index of Dental Anxiety and Fear, IDAF-4C), (d) discrimination validity (i.e., the difference in scores between the subjects with and without a habit of a regular dental visit, and (e) the construct validity from a confirmatory factor analysis (CFA). Results. The T-MDAS showed good internal consistency (Cronbach’s α = 0.88) and temporal stability (ρ = 0.69, p

Abstract Background Dental fear is associated with the experience of prior dental treatment and avoidance of dental visits. It remains unclear if individuals show an intention of avoidance (IA) towards treatments that they have not received (i.e., non-experienced dental treatment). The study aims to investigated (a) if individuals showed an increased fear and IA to non-experienced, compared to experienced dental treatment, and (b) if fear and IA to non-experienced treatment is associated with dental anxiety. Methods Fear/IA of 12 common conditions of dental treatment of 402 adults were investigated. If subjects have experienced the condition, fear and IA were assessed based on subjects’ prior experience (i.e., ExpFear/ExpIA). If they have not experienced the condition, fear and IA were assessed based on their anticipation (i.e., NExpFear/NExpIA). Trait dental anxiety was assessed using the Index of Dental Anxiety and Fear (IDAF-4C+). Results (A) NExpFear and NExpIA were significantly higher than ExpFear and ExpIA, respectively. (B) The IDAF-4C+ scores are positively correlated with NExpFear/NExpIA and negatively correlated with the magnification of fear (i.e., the discrepancy in the fear/IA of non-experienced vs. experienced conditions). (C) The condition ‘extraction of a wisdom tooth’ and ‘root canal treatment’ showed the highest ratings on NExpFear. Conclusions Individuals may develop a high degree of fear and IA of the treatment they have not received. Trait dental anxiety plays a key role in the fear of non-experienced treatment.

Abstract Background Our previous studies demonstrated that the administration of crude Polysaccharide from Panax notoginseng (CPPN) can effectively prolong the lifespan of tumor-bearing mice via boosting the host immune system as well as weak cytotoxicity against hepatocellular carcinoma (HCC). In the present study, Neutral Polysaccharide (NPPN) were further purified from crude polysaccharide isolated from panax notoginseng. The effects of NPPN on the immune function and hematopoietic function of mice with low immunity and myelosuppression induced by cyclophosphamide (CTX) were investigated. The effect of NPPN combined with CTX on the tumor inhibition rate of the H22 tumor-bearing mice and the impact of NPPN on the proliferation of H22 liver cancer cells in vitro were investigated. Methods CPPN was obtained by water extraction and alcohol precipitation method, and further purified by DEAE Sepharose Fast Flow ion exchange resin column. NPPN was added to the immunosuppressed with myelosuppression mice induced by CTX. Thymus index, spleen index, lymphocyte proliferation stimulation index by adding of concanavalin A, determination of serum hemolysin, NK cell activity assay, mice carbon clearance experiment, blood count tests were detected. The tumor inhibition rate of the H22 tumor-bearing mice treated with NPPN combined with CTX was recorded. Results NPPN and 4 kinds of acid polysaccharide from Panax notoginseng (APPN) were successfully isolated from the CPPN by DEAE Sepharose Fast Flow ion exchange resin column. NPPN inhibited the growth of H22 cells and significantly increase the tumor inhibition rate of the H22 tumor-bearing mice combined with CTX. The elevation of the cellular and humoral immunity levels as well as a variety of blood count tests indicators of immunosuppressive with myelosuppression mice may contribute to the antitumor activity of NPPN. Conclusion NPPN has a potential antitumor activity for the treatment of liver cancer combined with cyclophosphamide.

Acidity and tannins are among the grape berry quality traits that influence wine quality. Despite advantageous environmental tolerances of Vitis aestivalis-derived 'Norton', its acidity and tannin concentrations often deviate from expectations set for V. vinifera. Identification of the genetic determinants of malic acid, tartaric acid, pH, and tannin can assist in the improvement of new hybrid cultivars. For this purpose, a 'Norton' and V. vinifera 'Cabernet Sauvignon' hybrid population containing 223 individuals was used to construct a linkage map containing 384 simple sequence repeat (SSR) and 2,084 genotyping-by-sequencing (GBS)-derived single nucleotide polymorphism (SNP) markers. The resulting map was 1,441.9 cM in length with an average inter-marker distance of 0.75 cM and spanned 19 linkage groups (LGs). Quantitative trait loci (QTLs) were detected for malic acid, tartaric acid, pH, and tannin. QTLs for malic acid (LG 8) and pH (LG 6) were observed across multiple years and explained approximately 17.7% and 18.5% of the phenotypic variation, respectively. Additionally, QTLs for tartaric acid were identified on linkage groups 1, 6, 7, 9, and 17 and tannin on LG 2 in single-year data. The QTLs for tartaric acid explained between 8.8−14.3% and tannin explained 24.7% of the phenotypic variation. The markers linked to these QTLs can be used to improve hybrid cultivar breeding through marker-assisted selection.

BackgroundWhether women have a higher risk of adverse events compared with men following coronary angiography (CAG) and percutaneous coronary intervention (PCI) remains controversial. We aimed to investigate the sex differences in characteristics, treatments and outcomes among patients undergoing CAG and PCI in a large Chinese cohort.MethodsWe analyzed patients undergoing CAG and/or PCI in this multi-center registry cohort study Cardiorenal ImprovemeNt II (CIN-II) in 5 Chinese tertiary hospitals from 2007 to 2020. Clinical characteristics, treatment (discharge medication and PCI) and in-hospital outcomes (mortality and major bleeding) were compared between women and men.ResultsTotally 141,459 patients underwent CAG (44,362 [31.4%] women), of which 69,345 patients underwent PCI (15,376 [22.2%] women). Women were older (64.4 vs. 60.8 years), had more chronic comorbidities and lower PCI rate for stable coronary artery disease (CAD) than men (52.8 vs. 64.2%). Women received less CAG and PCI procedures. Among women undergoing PCI they received similar discharge medication treatment. In addition, women undergoing PCI had mildly lower rate of major bleeding (0.2 vs. 0.3%, P = 0.033) but higher in-hospital mortality (1.2 vs. 0.8%, P < 0.001). After adjustment, women had a higher risk in the major bleeding (adjusted odds ratio, 2.04 [95% CI: 1.07 to 3.62]), and the in-hospital mortality (adjusted odds ratio, 1.87 [95% CI: 1.36 to 2.56]).ConclusionAmong our Chinese cohort, women are older with more chronic comorbidities, receiving less PCI procedure and similar discharge medication treatment. Women have nearly 90% higher risk of in-hospital mortality and over 1-fold increased risk of major bleeding after PCI compared with men.

BackgroundA novel avian influenza A (H7N9) virus has caused great morbidity as well as mortality since its emergence in Eastern China in February 2013. However, the possible risk factors for death are not yet fully known.Methods and findingsPatients with H7N9 virus infection between March 1 and August 14, 2013 in Jiangsu province were enrolled. Data were collected with a standard form. Mean or percentage was used to describe the features, and Fisher's exact test or t-test test was used to compare the differences between fatal and nonfatal cases with H7N9 virus infection. A total of 28 patients with H7N9 virus infection were identified among whom, nine (32.1%) died. The median age of fatal cases was significant higher than nonfatal cases (PConclusionsAmong cases with H7N9 virus infection, increased age accompanied by co-morbidities was the risk of death. The severity of lung infection at admission, the persistence of lymphocytopenia, and the extended duration of lower oxygenation index all contributed to worsened outcomes of patients with H7N9 virus infection.

Immune checkpoint inhibitors (ICIs) have revealed significant clinical values in different solid tumors and hematological malignancy, changing the landscape for the treatment of multiple types of cancer. However, only a subpopulation of patients has obvious tumor response and long-term survival after ICIs treatment, and many patients may experience other undesirable clinical features. Therefore, biomarkers are critical for patients to choose exact optimum therapy. Here, we reviewed existing preclinical and clinical biomarkers of immunotherapeutic efficacy and immune-related adverse events (irAEs). Based on efficacy prediction, pseudoprogression, hyperprogressive disease, or irAEs, these biomarkers were divided into cancer cell-derived biomarkers, tumor microenvironment-derived biomarkers, host-derived biomarkers, peripheral blood biomarkers, and multi-modal model and artificial intelligence assessment-based biomarkers. Furthermore, we describe the relation between ICIs efficacy and irAEs. This review provides the overall perspective of biomarkers of immunotherapeutic outcome and irAEs prediction during ICIs treatment. [ABSTRACT FROM AUTHOR]

There are pedagogical challenges for the ideal balance of online community building and interaction among students and instructors for HyFlex learning. One of the challenges focuses on how instructors can effectively select and design an online discussion modality to promote positive, vigorous, and encouraging online asynchronous discussion to engage students. This research study adopted an exploratory mixed method approach designed to investigate student's satisfaction level and academic performance with different interface design platforms for online discussion in HyFlex delivery modality education courses. Study results indicated that different interface design for online discussion platforms had a significant impact on students' academic achievement for online discussion assessment although there is no significant impact on students' overall satisfactory levels toward the courses. Implications from the results suggest a need to design and integrate effective online discussion platform to engage students and promote social learning in HyFlex learning environments. [ABSTRACT FROM AUTHOR]

The main purpose of this study was to provide instructional suggestions for supporting science learning in digital environments based on a review of eye tracking studies in e-learning related areas. Thirty-three eyetracking studies from 2005 to 2014 were selected from the Social Science Citation Index (SSCI) database for review. Through a literature analysis program, CATA, and in-depth content analysis of the research methods and findings, five research theme clusters were abstracted from the selected papers, namely, cognitive activities in processing multimedia presentations, multimedia effects, roles of personal factors, effects of instructional design, and learning with dynamic e-platforms. Based on the results of the in-depth theme analyses, it is suggested that the design of e-learning instruction should consider placing related text and graphics in adjacent areas, using one verbal mode at a time, and providing explicit and clear verbal explanations. When using animations, instructors need to explain carefully the goals and contents of the animations to reduce the extraneous cognitive load. In the dynamic learning environment, a pre-training program is necessary for students to become familiar with the new environment. Finally, individual differences such as background knowledge, cognitive abilities and cognitive styles should be taken into consideration in the instructional design. [ABSTRACT FROM AUTHOR]

Avian influenza A(H7N9) virus has caused 5 epidemic waves in China since its emergence in 2013. We investigated the dynamic changes of antibody response to this virus over 1 year postinfection in 25 patients in Suzhou City, Jiangsu Province, China, who had laboratory-confirmed infections during the fifth epidemic wave, October 1, 2016-February 14, 2017. Most survivors had relatively robust antibody responses that decreased but remained detectable at 1 year. Antibody response was variable; several survivors had low or undetectable antibody titers. Hemagglutination inhibition titer was >1:40 for <40% of the survivors. Measured in vitro in infected mice, hemagglutination inhibition titer predicted serum protective ability. Our findings provide a helpful serologic guideline for identifying subclinical infections and for developing effective vaccines and therapeutics to counter H7N9 virus infections. [ABSTRACT FROM AUTHOR]

Background: H7N9 continues to cause human infections and remains a pandemic concern. Understanding the economic impacts of this novel disease is important for making decisions on health resource allocation, including infectious disease prevention and control investment. However, there are limited data on such impacts. Methods: Hospitalized laboratory-confirmed H7N9 patients or their families in Jiangsu Province of China were interviewed. Patients' direct medical costs of hospitalization were derived from their hospital bills. A generalized linear model was employed to estimate the mean direct medical costs of patients with different characteristics. Results: The mean direct cost of hospitalization for H7N9 was estimated to be ¥ 71 060 (95 % CI, 48 180-104 820), i.e., US$ 10 996 (95 % CI, 7 455-16 220), and was ¥12 060 (US$ 1 861), ¥136 120 (US$ 21 001) and ¥218 610 (US$ 33 728) for those who had mild or severe symptoms or who died, respectively. The principal components of the total fees differed among patients with different disease severity, although medication fees were always the largest contributors. Disease severity, proportion of reimbursement and family member monthly average income were identified as the key factors that contributed to a patient's direct medical cost of hospitalization. Conclusions: The direct medical costs of hospitalized patients with H7N9 are significant, and far surpass the annual per capita income of Jiangsu Province, China. The influencing factors identified should be taken into account when developing related health insurance policies and making health resource allocation. Trial registration: Not applicable. This is a survey study with no health care intervention implemented on human participants. [ABSTRACT FROM AUTHOR]

In the nitrate-responsive, homodimeric NarX sensor, two cytoplasmic membrane α-helices delimit the periplasmic ligand-binding domain. The HAMP domain, a four-helix parallel coiled-coil built from two α-helices (HD1 and HD2), immediately follows the second transmembrane helix. Previous computational studies identified a likely coiled-coil-forming α-helix, the signaling helix (S helix), in a range of signaling proteins, including eucaryal receptor guanylyl cyclases, but its function remains obscure. In NarX, the HAMP HD2 and S-helix regions overlap and apparently form a continuous coiled-coil marked by a heptad repeat stutter discontinuity at the distal boundary of HD2. Similar composite HD2-S-helix elements are present in other sensors, such as Sln1p from Saccharomyces cerevisiae. We constructed deletions and missense substitutions in the NarX S helix. Most caused constitutive signaling phenotypes. However, strongly impaired induction phenotypes were conferred by heptad deletions within the S-helix conserved core and also by deletions that remove the heptad stutter. The latter observation illuminates a key element of the dynamic bundle hypothesis for signaling across the heptad stutter adjacent to the HAMP domain in methyl-accepting chemotaxis proteins (Q. Zhou, P. Ames, and J. S. Parkinson, Mol. Microbiol. 73:801-814, 2009). Sequence comparisons identified other examples of heptad stutters between a HAMP domain and a contiguous coiled-coil-like heptad repeat sequence in conventional sensors, such as CpxA, EnvZ, PhoQ, and QseC; other S-helix-containing sensors, such as BarA and TorS; and the Neurospora crassa Nik-1 (Os-1) sensor that contains a tandem array of alternating HAMP and HAMP-like elements. Therefore, stutter elements may be broadly important for HAMP function. [ABSTRACT FROM AUTHOR]

The NarX–NarL and NarQ–NarP sensor–response regulator pairs control Escherichia coli gene expression in response to nitrate and nitrite. Previous analysis suggests that the Nar two-component systems form a cross-regulation network in vivo. Here we report on the kinetics of phosphoryl transfer between different sensor–regulator combinations in vitro. NarX exhibited a noticeable kinetic preference for NarL over NarP, whereas NarQ exhibited a relatively slight kinetic preference for NarL. These findings were substantiated in reactions containing one sensor and both response regulators, or with two sensors and a single response regulator. We isolated 21 NarX mutants with missense substitutions in the cytoplasmic central and transmitter modules. These confer phenotypes that reflect defects in phospho-NarL dephosphorylation. Five of these mutants, all with substitutions in the transmitter DHp domain, also exhibited NarP-blind phenotypes. Phosphoryl transfer assays in vitro confirmed that these NarX mutants have defects in catalysing NarP phosphorylation. By contrast, the corresponding NarQ mutants conferred phenotypes indicating comparable interactions with both NarP and NarL. Our overall results reveal asymmetry in the Nar cross-regulation network, such that NarQ interacts similarly with both response regulators, whereas NarX interacts preferentially with NarL. [ABSTRACT FROM AUTHOR]

The enterobacterium Klebsiella oxytoca uses a variety of inorganic and organic nitrogen sources, including purines, nitrogen-rich compounds that are widespread in the biosphere. We have identified a 23-gene cluster that encodes the enzymes for utilizing purines as the sole nitrogen source. Growth and complementation tests with insertion mutants, combined with sequence comparisons, reveal functions for the products of these genes. Here, we report our characterization of 12 genes, one encoding guanine deaminase and the others encoding enzymes for converting (hypo)xanthine to allantoate. Conventionally, xanthine dehydrogenase, a broadly distributed molybdoflavoenzyme, catalyzes sequential hydroxylation reactions to convert hypoxanthine via xanthine to urate. Our results show that these reactions in K. oxytoca are catalyzed by a two-component oxygenase (HpxE-HpxD enzyme) homologous to Rieske nonheme iron aromatic-ring-hydroxylating systems, such as phthalate dioxygenase. Our results also reveal previously undescribed enzymes involved in urate oxidation to allantoin, catalyzed by a flavoprotein monooxygenase (HpxO enzyme), and in allantoin conversion to allantoate, which involves allantoin racemase (HpxA enzyme). The pathway also includes the recently described PuuE allantoinase (HpxB enzyme). The HpxE-HpxD and HpxO enzymes were discovered independently by de la Riva et al. (L. de la Riva, J. Badia, J. Aguilar, R. A. Bender, and L. Baldoma, J. Bacteriol. 190:7892-7903, 2008). Thus, several enzymes in this K. oxytoca purine utilization pathway differ from those in other microorganisms. Isofunctional homologs of these enzymes apparently are encoded by other species, including Acinetobacter, Burkholderia, Pseudomonas, Saccharomyces, and Xanthomonas. [ABSTRACT FROM AUTHOR]

Recently, transcranial color-coded sonography (TCCS) has been found to have a diagnostic value in patients with idiopathic Parkinson's disease (IPD), which displays increased hyperechogenicity at the substantia nigra (SN). To use TCCS, to assess the difference in SN hyperechogenicity and intracranial hemodynamics among subjects with IPD, vascular parkinsonism (VP) and controls. Eighty IPD and 30 VP patients, and 60 controls were recruited into this study. The hyperechogenicity area at the SN and midbrain were calculated by encircling the outer circumference from the ipsilateral temporal window, using TCCS in each subject. The hemodynamics of intracranial large arteries, including flow velocity and pulsatility index (PI), were also measured. The presence of SN hyperechogenicity was significantly higher in the IPD patients than in the VP patients and controls (84% vs. 20% & 5%, respectively, p < 0.001). In IPD patients, the SN hyperechogenicity was correlated with the neurological severity and disease duration. Twenty-five (66.7%) VP patients had obvious vascular abnormality, as seen in TCCS study. The mean PI was significantly more elevated in the VP patients than those in the IPD patients and controls (all p < 0.05), but there was no significant difference of flow velocities among the VP, IPD patients and controls. TCCS, combining B-mode imaging for SN echogenicity and trancranial Doppler for intracranial hemodynamics, is a useful diagnostic tool in the differentiation between IPD and VP. These findings also suggest that multiple subcortical vascular lesions may damage the basal ganglia and thalamocortical circuit and result in parkinsonism features in VP patients. [ABSTRACT FROM AUTHOR]

In the U.S., several large-scale technology collaboration projects are going on with a common attempt to increase K-12 students' math and science performance. One example of such a project is the technology collaboration project described in this article that was carried out between a graduate program at a state university in northern California and a government research center in charge of math, science and astronomy in northern California. Technology collaborations provide ways to heighten student learning by exposing the educator/student to new content and technology, real world experiences, career guidance and community resources. The purposes of technology collaboration are to create real-world environments that employ the context in which learning is relevant, and to focus on realistic approaches to solving problems embracing the concepts of applying constructivism to the development of learning environments.

The HAMP linker, a predicted structural element observed in many sensor kinases and methyl-accepting chemotaxis proteins, transmits signals between sensory input modules and output modules. HAMP linkers are located immediately inside the cytoplasmic membrane and are predicted to form two short amphipathic α-helices (AS-1 and AS-2) joined by an unstructured connector. HAMP linkers are found in the Escherichia coli nitrate- and nitrite-responsive sensor kinases NarX and NarQ (which respond to ligand by increasing kinase activity) and the sensor kinase CpxA (which responds to ligand by decreasing kinase activity). We constructed a series of hybrids with fusion points throughout the HAMP linker, in which the sensory modules of NarX or NarQ are fused to the transmitter modules of NarX, NarQ, or CpxA. A hybrid of the NarX sensor module and the CpxA HAMP linker and transmitter module (NarX-CpxA-1) responded to nitrate by decreasing kinase activity, whereas a hybrid in which the HAMP linker of NarX was replaced by that of CpxA (NarX-CpxANarX-1) responded to nitrate by increasing kinase activity. However, sequence variations between HAMP linkers do not allow free exchange of HAMP linkers or their components. Certain deletions in the NarX HAMP linker resulted in characteristic abnormal responses to ligand; similar deletions in the NarQ and NarX-CpxA-1 HAMP linkers resulted in responses to ligand generally similar to those seen in NarX. We conclude that the structure and action of the HAMP linker are conserved and that the HAMP linker transmits a signal to the output domain that ligand is bound. [ABSTRACT FROM AUTHOR]

The aim of this study was to clarify whether phenotypic variation exists when subjects with different genotypes of cytochrome P450 2E1 (CYP2E1) are exposed to N,N-dimethylformamide (DMF). The genotypes of CYP2E1 were confirmed in 123 healthy male volunteer subjects. Of the 123 subjects, the numbers of c1 homozygotes, c2 heterozygotes, and c2 homozygotes were 77, 45, and 1, respectively. Seven of the c1 homozygotes, five of the c2 heterozygotes, and the one c2 homozygote (mean age: 22.7 years, range: 20–27 years) were exposed to DMF vapor twice, once via the skin and once via the lung, for a total of 8 h per subject at a concentration below 10 ppm, the occupational exposure limit recommended by the Japan Society for Occupational Health, the American Conference of Governmental and Industrial Hygienists, and Deutsche Forschungsgemeinschaft, at 27°C and 44% relative humidity. Exposure levels were 6.2±1.0 ppm in dermal exposure and 7.1±1.0 ppm in inhalation exposure. Urine samples were collected until 72 h after exposure. The half-lives of urinary N-methylformamide (NMF) were obtained as the phenotype. The average urinary NMF half-lives of the c1 homozygotes, the c2 heterozygotes, and the c2 homozygote were 3.86±1.90, 4.38±1.53, and 4.2 h after dermal exposure, and 1.58±0.42, 1.84±0.61, and 3.2 h after respiratory exposure. The NMF half-lives of the c1 homozygotes were not significantly different from those of the c2 heterozygotes, and there were no differences between the NMF half-lives on the subjects with and without the c2 allele. Even though the data were obtained from only one c2 homozygote, it is noteworthy that the NMF half-life of this subject was slightly less than that of the c1 homozygotes after respiratory exposure. [ABSTRACT FROM AUTHOR]

This study investigated the effects of different thermal sterilization conditions on the structural and functional properties of whey and caseins in goat milk. The commonly used industrial sterilization conditions including 65 ℃ for 30 min, 80 ℃ for 30 s, 95 ℃ for 5 min and 135 ℃ for 4 s were selected to treat goat milk, and whey and casein proteins were separated from the treated milk. Circular dichroism (CD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, fluorescence spectroscopy, laser confocal scanning microscopy (LCSM) and atomic force microscopy (AFM) were used to analyze the changes in protein structure and properties. The results showed that the structures of whey and casein proteins changed little after treatment at 65 ℃ for 30 min and 80 ℃ for 30 s, and the increase in protein unfolding and surface hydrophobicity resulted in better foaming and emulsifying properties of whey and casein proteins. The treatments at 95 ℃ for 5 min and 135 ℃ for 4 s resulted in a significant decrease in the relative content of α-helix, a significant increase in the relative content of random coil, severe denaturation of the proteins, and a decrease in solubility and surface hydrophobicity, which adversely affected the stability of functional properties of goat milk proteins. The above results provide a reference for optimizing the quality and stability of goat milk products, and help to develop functional goat milk products.

Escherichia coli, a facultative aerobe, expresses two distinct respiratory nitrate reductases. The periplasmic NapABC enzyme likely functions during growth in nitrate-limited environments, whereas the membrane-bound NarGHI enzyme functions during growth in nitrate-rich environments. Maximal expression of the napFDAGHBC operon encoding periplasmic nitrate reductase results from synergistic transcription activation by the Fnr and phospho-NarP proteins, acting in response to anaerobiosis and nitrate or nitrite, respectively. Here, we report that, during anaerobic growth with no added nitrate, less-preferred carbon sources stimulated napF operon expression by as much as fourfold relative to glucose. Deletion analysis identified a cyclic AMP receptor protein (Crp) binding site upstream of the NarP and Fnr sites as being required for this stimulation. The napD and nrfA operon control regions from Shewanella spp. also have apparent Crp and Fnr sites, and expression from the Shewanella oneidensis nrfA control region cloned in E. coli was subject to catabolite repression. In contrast, the carbon source had relatively little effect on expression of the narGHJI operon encoding membrane-bound nitrate reductase under any growth condition tested. Carbon source oxidation state had no influence on synthesis of either nitrate reductase. The results suggest that the Fnr and Crp proteins may act synergistically to enhance NapABC synthesis during growth with poor carbon sources to help obtain energy from low levels of nitrate. [ABSTRACT FROM AUTHOR]

Hierarchical control ensures that facultative bacteria preferentially use the available respiratory electron acceptor with the most positive standard redox potential. Thus, nitrate is used before other electron acceptors such as fumarate for anaerobic respiration. Nitrate regulation is mediated by the NarX-NarL two-component system, which activates the transcription of operons encoding nitrate respiration enzymes and represses the transcription of operons for other anaerobic respiratory enzymes, including enzymes involved in fumarate respiration. These are fumarate reductase (encoded by the frdABCD operon), fumarase B, which generates fumarate from malate, and the DcuB permease for fumarate, malate, and aspartate. The transcription of the corresponding structural genes is activated by the DcuS-DcuR two-component system in response to fumarate or its dicarboxylate precursors. We report results from preliminary transcription microarray experiments that revealed two previously unknown members of the NarL regulon: the aspA gene encoding aspartate-ammonia lyase, which generates fumarate; and the dcuSR operon encoding the dicarboxylate-responsive regulatory system. We measured beta-galactosidase expression from monocopy aspA-lacZ, frdA-lacZ, and dcuS-lacZ operon fusions in response to added nitrate and fumarate and with respect to the dcuR and narL genotypes. Nitrate, acting through the NarX-NarL regulatory system, repressed the transcription of all three operons. Only frdA-lacZ expression, however, was responsive to added fumarate or a dcuR+ genotype. Phospho-NarL protein protected operator sites in the aspA and dcuS promoter regions from DNase I cleavage in vitro. The overall results are consistent with the hypothesis that nitrate represses frdA operon transcription not only directly, by repressing frdA promoter activity, but also indirectly, by repressing dcuS promoter activity. [ABSTRACT FROM AUTHOR]

Tumor suppressor p53 has been implicated in cell stress response and determines cell fate of either growth arrest or apoptosis. Heat shock proteins (Hsps) expressed under stress usually confer survival protection to the cell or interruption in the apoptotic pathways. Although Hsp90 can physically interact with p53, whether or not the hsp90 gene is influenced downstream of p53 in UV irradiation-induced apoptosis remains unclear. We have found that the level of p53 is elevated with the decline of Hsp90 in UV-irradiated cells and that malfunction of Hsp90, as inhibited by geldanamycin, enhances the p53-involved UV irradiation-induced apoptosis. In addition, the expression of the hsp90β gene was reduced in both UV-irradiated and wild type p53-transfected cells. These results suggest a negative correlation between the trans factor p53 and a chaperone gene hsp90β in apoptotic cells. Mutation analysis demonstrated that the p53 binding site in the first exon was indispensable for p53 regulation on the hsp90β gene. In addition, with p53 bound at the promoter of the hsp90β gene, mSin3a and p300 were differentially recruited in UV irradiation-treated or untreated Jurkat cells in vivo. The evidence of p53-repressed hsp90β gene expression in UV-irradiated cells shed light on a novel pathway of Hsp90 in the survival control of the stressed cells. [ABSTRACT FROM AUTHOR]

NarX-NarL and NarQ-NarP are paralogous two-component regulatory systems that control Escherichia coli gene expression in response to the respiratory oxidants nitrate and nitrite. Nitrate stimulates the autophosphorylation rates of the NarX and NarQ sensors, which then phosphorylate the response regulators NarL and NarP to activate and repress target operon transcription. Here, we investigated both the autophosphorylation and dephosphorylation of soluble sensors in which the maltose binding protein (MBP) has replaced the amino-terminal transmembrane sensory domain. The apparent affinities (Km) for ADP were similar for both proteins, about 2 μM, whereas the affinity of MBP-NarQ for ATP was lower, about 23 μM. At a saturating concentration of ATP, the rate constant of MBP-NarX autophosphorylation (about 0.5 × 10-4 s-1) was lower than that observed for MBP-NarQ (about 2.2 x 10-4 s-1). At a saturating concentration of ADP, the rate constant of dephosphorylation was higher than that of autophosphorylation, about 0.03 s-1 for MBP-NarX and about 0.01 s-1 for MBP-NarQ. For other studied sensors, the published affinities for ADP range from about 16 μM (KinA) to about 40 μM (NtrB). This suggests that only a small proportion of NarX and NarQ remain phosphorylated in the absence of nitrate, resulting in efficient response regulator dephosphorylation by the remaining unphosphorylated sensors. [ABSTRACT FROM AUTHOR]