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Wear of Bulk-fill Composite Resins After Thermo-mechanical Loading. Oper Dent 2023:493222. [PMID: 37226712 DOI: 10.2341/22-039-l] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/24/2023] [Indexed: 05/26/2023]
Abstract
STATEMENT OF PROBLEM Wear of conventional composite resin presented many challenges when restoring posterior teeth and resulted in clinical complications. Bulk-fill composite resins have been proposed as a more suitable and wear-resistant alternative. OBJECTIVE To evaluate and compare the volumetric wear (mm3) of bulk-fill composite resins to a conventional composite resin and enamel after thermo-mechanical loading. METHODS AND MATERIALS Five composite resins (n=10) were evaluated: four bulk-fill composite resins (Filtek One Bulk Fill [3M Oral Care], Tetric EvoCeram Bulk Fill [Ivoclar Vivadent], Tetric PowerFill [Ivoclar Vivadent], SonicFill 3 [Kerr Corp]); and one conventional composite resin (Filtek Supreme Ultra [3M Oral Care]). Enamel from recently extracted human teeth was used as a control. Specimens were subjected to a 2-body volumetric wear evaluation using a chewing simulator (CS-4.8, Mechatronik). Disc-shaped specimens (10 mm in diameter × 3 mm in thickness) received 500,000 load cycles against steatite antagonists while simultaneously thermocycled (5000 cycles, 5-55°C). Volumetric wear (mm3) was measured using the Geomagic Control X software (3D Systems) based on digital scans of the specimens obtained before and after thermo-mechanical loading, with a Trios 3 (3Shape) digital scanner. Scanning electron microscopy analysis of wear facets and composite resin filler shape and size was performed. Volumetric wear was statistically analyzed using the one-way ANOVA and Tukey's post-hoc test (α=0.05). RESULTS All tested composite resins wore at rates significantly higher than enamel (p<0.05). The mean volumetric wear of the composite resins ranged from 1.01 mm3 to 1.48 mm3, while enamel had a mean volumetric wear of 0.25 mm3. Bulk-fill composite resins showed higher wear resistance than the conventional composite resin (p<0.05). CONCLUSIONS Bulk-fill composite resins showed higher wear resistance than the conventional composite resin, and both types of composite resin were not as wear-resistant as enamel.
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Five-year Clinical Evaluation of Universal Adhesives in Noncarious Cervical Lesions. Oper Dent 2023:493223. [PMID: 37226698 DOI: 10.2341/21-132-c] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/27/2022] [Indexed: 05/26/2023]
Abstract
OBJECTIVES To compare the clinical performance of mildly acidic universal adhesives Scotchbond Universal (SU, 3M Oral Care, St Paul, MN, USA) and Prime & Bond Elect (PBE, Dentsply Sirona, Charlotte, NC, USA) in the restoration of noncarious cervical lesions (NCCLs). METHODS AND MATERIALS A total of 63 patients in need of 203 NCCL restorations participated in this randomized controlled clinical trial. Notch-shaped lesions were restored with Kalore (GC Corporation, Tokyo, Japan) after application of either SU or PBE, following the etch-and-rinse (ER) or self-etch (SE) techniques. Subjects were followed up for 60 months. The focus of the statistical analyses was on the change of outcome over time as assessed by the Modified USPHS rating system (ie, Alfa vs Bravo + Charlie outcomes). Logistic regression was performed for each outcome separately with compound symmetric variance-covariance structure assumed to consider a correlation of restorations within subjects. All analyses were conducted using SAS 9.4 (SAS, Cary, NC, USA). RESULTS One-hundred twenty-nine teeth in 35 subjects were assessed at the 60-month follow-up. In addition, three restorations that failed prior to the 60-month evaluation, two of which were in subjects who did not present for the 60-month follow-up, were included in the statistical analysis. In total, two restorations in the SU_ER group and three restorations in the PBE_SE group failed the retention category. Statistically significant differences were obtained for the comparison of restorations in the PBE_SE and PBE_ER groups, where the former was 58% less likely to maintain a score of Alfa for marginal discoloration than the latter. CONCLUSIONS SU and PBE demonstrated acceptable clinical performance at 60 months with regard to restoration retention. Phosphoric-acid etching of the NCCLs prior to adhesive application significantly improved the performance of PBE in regard to marginal discoloration.
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Search for Gamma-Ray Spectral Lines from Dark Matter Annihilation up to 100 TeV toward the Galactic Center with MAGIC. PHYSICAL REVIEW LETTERS 2023; 130:061002. [PMID: 36827578 DOI: 10.1103/physrevlett.130.061002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 11/02/2022] [Accepted: 12/15/2022] [Indexed: 06/18/2023]
Abstract
Linelike features in TeV γ rays constitute a "smoking gun" for TeV-scale particle dark matter and new physics. Probing the Galactic Center region with ground-based Cherenkov telescopes enables the search for TeV spectral features in immediate association with a dense dark matter reservoir at a sensitivity out of reach for satellite γ-ray detectors, and direct detection and collider experiments. We report on 223 hours of observations of the Galactic Center region with the MAGIC stereoscopic telescope system reaching γ-ray energies up to 100 TeV. We improved the sensitivity to spectral lines at high energies using large-zenith-angle observations and a novel background modeling method within a maximum-likelihood analysis in the energy domain. No linelike spectral feature is found in our analysis. Therefore, we constrain the cross section for dark matter annihilation into two photons to ⟨σv⟩≲5×10^{-28} cm^{3} s^{-1} at 1 TeV and ⟨σv⟩≲1×10^{-25} cm^{3} s^{-1} at 100 TeV, achieving the best limits to date for a dark matter mass above 20 TeV and a cuspy dark matter profile at the Galactic Center. Finally, we use the derived limits for both cuspy and cored dark matter profiles to constrain supersymmetric wino models.
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Adjudicating Mild Cognitive Impairment Due to Alzheimer's Disease as a Novel Endpoint Event in the TOMMORROW Prevention Clinical Trial. J Prev Alzheimers Dis 2022; 9:625-634. [PMID: 36281666 DOI: 10.14283/jpad.2022.72] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
BACKGROUND The onset of mild cognitive impairment (MCI) is an essential outcome in Alzheimer's disease (AD) prevention trials and a compelling milestone for clinically meaningful change. Determining MCI, however, may be variable and subject to disagreement. Adjudication procedures may improve the reliability of these determinations. We report the performance of an adjudication committee for an AD prevention trial. METHODS The TOMMORROW prevention trial selected cognitively normal participants at increased genetic risk for AD and randomized them to low-dose pioglitazone or placebo treatment. When adjudication criteria were triggered, a participant's clinical information was randomly assigned to a three-member panel of a six-member independent adjudication committee. Determination of whether or not a participant reached MCI due to AD or AD dementia proceeded through up to three review stages - independent review, collaborative review, and full committee review - requiring a unanimous decision and ratification by the chair. RESULTS Of 3494 participants randomized, the committee adjudicated on 648 cases from 386 participants, resulting in 96 primary endpoint events. Most participants had cases that were adjudicated once (n = 235, 60.9%); the rest had cases that were adjudicated multiple times. Cases were evenly distributed among the eight possible three-member panels. Most adjudicated cases (485/648, 74.8%) were decided within the independent review (stage 1); 14.0% required broader collaborative review (stage 2), and 11.1% needed full committee discussion (stage 3). The primary endpoint event decision rate was 39/485 (8.0%) for stage 1, 29/91 (31.9%) for stage 2, and 28/72 (38.9%) for stage 3. Agreement between the primary event outcomes supported by investigators' clinical diagnoses and the decisions of the adjudication committee increased from 50% to approximately 93% (after around 100 cases) before settling at 80-90% for the remainder of the study. CONCLUSIONS The adjudication process was designed to provide independent, consistent determinations of the trial endpoints. These outcomes demonstrated the extent of uncertainty among trial investigators and agreement between adjudicators when the transition to MCI due to AD was prospectively assessed. These methods may inform clinical endpoint determination in future AD secondary prevention studies. Reliable, accurate assessment of clinical events is critical for prevention trials and may mean the difference between success and failure.
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18-Month Clinical Performance of a Bulk-Fill Composite Resin In NCCLS. Dent Mater 2022. [DOI: 10.1016/j.dental.2021.12.061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Thoracoscopic management of congenital esophageal stenosis secondary to tracheobronchial remnant in pediatric patients. CIRUGIA PEDIATRICA : ORGANO OFICIAL DE LA SOCIEDAD ESPANOLA DE CIRUGIA PEDIATRICA 2021; 34:134-137. [PMID: 34254751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
INTRODUCTION Congenital esophageal stenosis (CES) is an extremely rare pathology in children, with an incidence of 1/25,000-50,000 live births. According to its histopathological classification, there are three types of CES: fibromuscular hyperplasia, membranous diaphragm, and tracheobronchial remnants. CLINICAL CASE We present the clinical case of a 39-month-old male patient diagnosed with CES secondary to tracheobronchial remnants, with multiple vomit and reflux episodes since he was 4 months old. He was admitted at the emergency department with respiratory distress. An upper GI endoscopy and an esophagogram were initially carried out. Stenosis resection and thoracoscopic esophageal anastomosis were performed. CONCLUSIONS Tracheobronchial remnants are the second most common presentation of congenital esophageal stenosis. They can be managed through dilatations or surgery according to etiology.
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Eribulin in metastatic breast cancer the UK experience: A multi-centre retrospective 577 patient study. Ann Oncol 2018. [DOI: 10.1093/annonc/mdy272.303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Complex history of dog (Canis familiaris) origins and translocations in the Pacific revealed by ancient mitogenomes. Sci Rep 2018; 8:9130. [PMID: 29904060 PMCID: PMC6002536 DOI: 10.1038/s41598-018-27363-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 05/31/2018] [Indexed: 11/22/2022] Open
Abstract
Archaeological evidence suggests that dogs were introduced to the islands of Oceania via Island Southeast Asia around 3,300 years ago, and reached the eastern islands of Polynesia by the fourteenth century AD. This dispersal is intimately tied to human expansion, but the involvement of dogs in Pacific migrations is not well understood. Our analyses of seven new complete ancient mitogenomes and five partial mtDNA sequences from archaeological dog specimens from Mainland and Island Southeast Asia and the Pacific suggests at least three dog dispersal events into the region, in addition to the introduction of dingoes to Australia. We see an early introduction of dogs to Island Southeast Asia, which does not appear to extend into the islands of Oceania. A shared haplogroup identified between Iron Age Taiwanese dogs, terminal-Lapita and post-Lapita dogs suggests that at least one dog lineage was introduced to Near Oceania by or as the result of interactions with Austronesian language speakers associated with the Lapita Cultural Complex. We did not find any evidence that these dogs were successfully transported beyond New Guinea. Finally, we identify a widespread dog clade found across the Pacific, including the islands of Polynesia, which likely suggests a post-Lapita dog introduction from southern Island Southeast Asia.
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Abstract
OBJECTIVE To evaluate the clinical performance of Scotchbond Universal (3M Oral Care) and Prime & Bond Elect (Dentsply Sirona) in the restoration of noncarious cervical lesions (NCCLs). METHODS AND MATERIALS This was a randomized controlled clinical trial involving 63 subjects. Two hundred and three NCCLs were restored using Scotchbond Universal and Prime & Bond Elect using both an etch-and-rinse and a self-etch technique. Lesions were notch-shaped NCCLs, and the restorations were placed without any mechanical retention. Restorations were finished immediately after placement and scored with regard to retention, marginal discoloration, marginal adaptation, and secondary caries. Similar assessment of the restorations was performed 18 months after placement. Logistic regression was performed for each outcome separately with a compound symmetric variance-covariance structure assumed to consider a correlation of restorations within subjects. All analyses were conducted using SAS version 9.4 (SAS Inc). RESULTS One hundred and fifty-eight teeth (77.8% of the restorations placed) in 46 subjects (73% of subjects enrolled) were available for the 18-month follow-up. A statistically significant difference was reached only for the comparison Scotchbond Universal/self-etch (SU_SE) and Prime & Bond Elect/etch-and-rinse (PBE_E&R) groups ( p=0.01), where a restoration with SU_SE was 66% less likely to maintain a score of Alpha for marginal discoloration than a restoration performed with PBE_E&R. CONCLUSIONS Scotchbond Universal and Prime & Bond Elect presented acceptable clinical performance after 18 months of clinical service. However, Scotchbond Universal, when applied with a self-etch approach, did demonstrate a relatively high level of marginal discoloration when compared to the other groups.
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Genomic variations associated with prostate cancer in large cohort of African American men. J Clin Oncol 2018. [DOI: 10.1200/jco.2018.36.6_suppl.20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
20 Background: Racial disparities in prostate cancer (PCa) incidence and mortality are well known. PCa is known to be more aggressive in African American men (AAM) in terms of higher incidence and mortality rates. Here we validate a tumor gene expression pan-cancer race model in men with PCa and further characterize genomic differences that may contribute to disparate clinical outcomes Methods: We obtained de-identified genome-wide expression profiles from clinical use of the Decipher RP test in 9,953 men from the GRID registry database. A subset of men (n = 313) had known race status. A pan-cancer race model, developed to predict patient AAM race from analysis of gene expression patterns in 4,162 tumors from retrospective cohorts with known race status was applied to the prospective cohort for race prediction. Gene expression data was used to define genomic differences. Results: The race model has an AUC of 0.98 discriminating EAM from AAM in independent PCa cohort. The model was then applied to the 9,640 GRID patients with unknown race status and classified 6,831 as EAM, 1,058 as AAM with 1,751 as having indeterminate race. Characterizing the molecular subtypes, we found known and predicted AAM to be enriched with SPINK1+ tumors (21% and 24%, respectively) compared to predicted EAM (8%). In contrast, while ERG+ was found 22% and 19% in known and predicted AAM, respectively compared to 46% in predicted EAM. Based on PAM50 prostate cancer classifier, 61% of AAM were classified as basal-like tumors, whereas 41% were basal-like in EAM. Similarly, 28% of AAM had low AR-A while only 11% of EAM had low AR-A. AAM tumors had higher levels of immune infiltration signatures as well as higher scores for inflammatory and interferon gamma responses, and Interleukin 6 (IL6) signaling activity scores. AAM had lower DNA repair and glycolysis pathway activity compared to EAM Conclusions: Known and predicted AAM, were enriched with SPINK1+ tumors, higher immune infiltration and activation but lower ERG+, DNA repair and AR activity tumors. Using such large GRID data with known race, we will further understand the underlying causes associated with prostate cancer racial disparities which could lead to personalized diagnosis and treatment.
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Transcriptomic heterogeneity of androgen receptor activity in primary prostate cancer: Identification and characterization of a low AR-active subclass. J Clin Oncol 2018. [DOI: 10.1200/jco.2018.36.6_suppl.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
2 Background: Significant genomic diversity exists in the androgen receptor ( AR) and its activity (AR-A) in mCRPC. In localized prostate cancer, the biologic, prognostic, and therapeutic clinical implications of AR-A heterogeneity have yet to be interrogated Methods: Genome-wide expression profiles of FFPE RP or biopsy tumor samples were evaluated from a prospective registry cohort (n = 5,239, NCT02609269) and six retrospective institutional cohorts (n = 1,170). AR-A was calculated based on expression of 9 targets of AR.. Results: Utilizing 6,409 localized prostate adenocarcinomas with full transcriptomic data, we found there was marked inter-individual transcriptomic diversity in AR and AR-A expression, and weak correlation between them (r = 0.08 to 0.36 based on cohort), in contrast to mCRPC that has a strong correlation between AR and AR-A expression (r = 0.76). Additionally, serum PSA had no correlation to intratumoral AR-A (r = 0.06). Unsupervised hierarchical clustering identified a distinct subclass of low AR-A prostate tumors, which had increased markers of immunogenicity (decreased T-regs and MDSCs, and increased CD3 effector T-cells), increased neuroendocrine marker expression ( NCAM1, ENO2, and SCG2), and decreased DNA repair pathway expression (all p < 0.001). Clinically, low AR-A tumors had more rapid development of metastatic disease in three independent cohorts, were more prone to develop resistance to hormonal therapy and develop CRPC, and were found at an increased frequency in African-American men. Interrogating in vitro drug sensitivity analyses utilizing the NCI-60 panel, low AR-A tumors appear more sensitive to platinum chemotherapy and PARP inhibition, and less sensitive to hormone therapy and taxanes. Conclusions: The diversity in AR-signaling in localized prostate cancer represents important biological heterogeneity that is both prognostic and predictive of treatment response. These findings are provocative in that low AR-A tumors may be more susceptible to immunotherapy, PARP inhibition, platinum chemotherapy, and/or radiotherapy. Patients with low AR-A tumors warrant dedicated biomarker enhanced clinical trials.
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Electrochemical surface engineering of magnesium metal by plasma electrolytic oxidation and calcium phosphate deposition: biocompatibility and in vitro degradation studies. RSC Adv 2018; 8:29189-29200. [PMID: 35548009 PMCID: PMC9084472 DOI: 10.1039/c8ra05278f] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 08/10/2018] [Indexed: 11/21/2022] Open
Abstract
In this study, the surface of magnesium metal was electrochemically engineered for enhanced biocompatibility and controlled degradation in body fluid. Firstly, a plasma electrolytic oxidation (PEO) coating was formed on magnesium, followed by electrochemical deposition of calcium phosphate (CaP) using an unconventional electrolyte. Cytocompatibility tests using L929 cells revealed that the PEO-CaP coating significantly improved the biocompatibility of magnesium. In vitro electrochemical degradation experiments in simulated body fluid (SBF) showed that the PEO-CaP coating improved the degradation resistance of magnesium significantly. The corrosion current density (icorr) of the PEO-CaP coated magnesium was ∼99% and ∼97% lower than that of bare magnesium and the PEO-only coated magnesium, respectively. Similarly, electrochemical impedance spectroscopy (EIS) results showed that the polarisation resistance (RP) of the PEO-CaP coated magnesium was one-order of magnitude higher as compared to the PEO-only coated magnesium and two-orders of magnitude higher than the bare magnesium, after 72 h immersion in SBF. Scanning electron microscopy (SEM) analysis revealed no localized degradation in the PEO-CaP coated magnesium. The study demonstrated that the PEO-CaP coating is a promising combination for enhancing the biocompatibility and reducing the degradation of magnesium for potential biodegradable implant applications. The PEO-CaP coating produced on magnesium metal using an unconventional electrolyte enhanced the degradation resistance and provided excellent cytocompatibility.![]()
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0493 ARE SPLIT-NIGHT POLYSOMNOGRAMS APPROPRIATE FOR PATIENTS IN HIGH-RISK PROFESSIONS? Sleep 2017. [DOI: 10.1093/sleepj/zsx050.492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Evidence of linkage in MSH6-associated region exclusive to high-risk African-American families with prostate cancer. J Clin Oncol 2017. [DOI: 10.1200/jco.2017.35.6_suppl.180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
180 Background: The significance of germline variants and their implications for prostate cancer (PCa) patients has gained prominence. Mismatch repair (MMR) genes such as MSH6 and MSH2, along with DNA repair genes, may be more important in PCa than previously appreciated. In the present study, we compared linkage results between African American (AA) and Caucasian (CA) PCa families with multiple affected family members. Methods: Study subjects were from 15 large, high-risk, clinically homogenous AA families and 4 CA families from Southern Louisiana. All families had at least ≥ 3 members with family member diagnosed with PCa. Genotyping for linkage analyses was done using Illumina Infinium II SNP HumanLinkage-12 panel. 6,068 SNPs were released for linkage analyses. Parametric linkage analyses were performed using Merlin software, version 1.1.2. An HLOD score > 1.86 was considered suggestive of linkage. Results: A total of 129 individuals from 15 AA families were genotyped including 45 affected men, 44 unaffected men, and 40 women. The average age at diagnosis was 61; 8 of 15 families had more than 4 affected individuals. 50 CA individuals from similar families were genotyped including 12 affected men, 26 presently unaffected men, and 12 women. For CA families, the average age of onset was 66, with at least 5 affected individuals in each family. In AAs, we identified a peak of suggestive linkage at chromosome 2p16 (HLOD = 1.97). Similarly, in CA families, the strongest linkage signal was observed on chromosome 2q14.1 with an HLOD score of 1.94. At the2 q14 linkage region, there was no linkage in AA PCa families (HLOD = 0.0004). Similarly, on 2p16, there was no linkage in the CA cohort (HLOD = 0). Conclusions: The MSH6 gene is located in 2p16 region. MMR gene mutations have been shown to have evidence of microsatellite instability in PCa as well as hereditary nonpolyposis colorectal cancer. MSH6 gene may represent a genetic variant contributing to risk of PCa in high risk AA families. This potentially has therapeutic implications for use of PD1 inhibitors in this population.
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Biocompatibility and in Vitro Degradation Behavior of Magnesium–Calcium Alloy Coated with Calcium Phosphate Using an Unconventional Electrolyte. ACS Biomater Sci Eng 2015; 2:56-64. [DOI: 10.1021/acsbiomaterials.5b00343] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Prognostic markers and response to vandetanib therapy in sporadic medullary thyroid cancer patients. Exp Clin Endocrinol Diabetes 2015. [DOI: 10.1055/s-0035-1547649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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High energy emission from the Galactic Center: Theory and observations. EPJ WEB OF CONFERENCES 2015. [DOI: 10.1051/epjconf/201510504002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Revisiting galvanomagnetic effects in conducting ferromagnets. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:432201. [PMID: 25299160 DOI: 10.1088/0953-8984/26/43/432201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The recently proposed coupling between the angular momentum density and magnetic moments is shown to provide a straightforward alternative explanation for galvanomagnetic effects, i.e. for both anisotropic magnetoresistance (AMR) and planar Hall effect (PHE). Such coupling naturally reproduces the general formula associated with AMR and PHE and allows for the occurrence of so-called 'negative AMR'. This coupling also provides a unifying link between AMR, PHE and the anomalous Hall effect (AHE) since this same coupling was previously found to give rise to AHE (Bellaiche et al 2013 Phys. Rev. B 88 161102).
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A mechanisticin vitrostudy of the microgalvanic degradation of secondary phase particles in magnesium alloys. J Biomed Mater Res A 2014; 103:990-1000. [DOI: 10.1002/jbm.a.35247] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 05/15/2014] [Accepted: 05/28/2014] [Indexed: 11/06/2022]
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SHOX2 Methylierung - ein Biomarker zur Optimierung der EBUS-TBNA Lymphknotenstadiierung. Pneumologie 2013. [DOI: 10.1055/s-0033-1334494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Stratigraphic and plant microfossil investigation at Cook's Cove, North Island, New Zealand: reinterpretation of Holocene deposits and evidence of Polynesian-introduced crops. J R Soc N Z 2011. [DOI: 10.1080/03036758.2010.524226] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
Abstract
Pharmacokinetic interactions between isoniazid and theophylline were studied in male Wistar rats, 206±17 g. Concomitant oral administration of 2 × 5 mg kg−1 isoniazid accelerated slightly the disposition of theophylline (10 mg kg−1, i.v.) whereas 2 × 25 mg kg−1 isoniazid slowed it marginally. The differences in distribution volume, systemic clearance and area under the concentration-time curve (AUC) between the high and the low dose, however, were statistically significant. One week pretreatment with 10 mg kg−1 isoniazid tended towards inhibition (significant decrease of systemic clearance, increase of AUC) and 50 mg kg−1 to acceleration (decrease of half-life, mean residence time and AUC, increase of systemic clearance) of theophylline disposition. After oral pretreatment with 20 mg kg−1 theophylline, neither the kinetics of free isoniazid (50 mg kg−1, i.v.) and the amount acetylated nor the acetylation indices differed from the controls. There was no evidence that concomitant or subacute administration of different doses of isoniazid affects major metabolic pathways of theophylline or that prolonged theophylline treatment interacts with the N-acetylation capacity.
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Abstract
Critical Zone (CZ) research investigates the chemical, physical, and biological processes that modulate the Earth's surface. Here, we advance 12 hypotheses that must be tested to improve our understanding of the CZ: (1) Solar-to-chemical conversion of energy by plants regulates flows of carbon, water, and nutrients through plant-microbe soil networks, thereby controlling the location and extent of biological weathering. (2) Biological stoichiometry drives changes in mineral stoichiometry and distribution through weathering. (3) On landscapes experiencing little erosion, biology drives weathering during initial succession, whereas weathering drives biology over the long term. (4) In eroding landscapes, weathering-front advance at depth is coupled to surface denudation via biotic processes. (5) Biology shapes the topography of the Critical Zone. (6) The impact of climate forcing on denudation rates in natural systems can be predicted from models incorporating biogeochemical reaction rates and geomorphological transport laws. (7) Rising global temperatures will increase carbon losses from the Critical Zone. (8) Rising atmospheric P(CO2) will increase rates and extents of mineral weathering in soils. (9) Riverine solute fluxes will respond to changes in climate primarily due to changes in water fluxes and secondarily through changes in biologically mediated weathering. (10) Land use change will impact Critical Zone processes and exports more than climate change. (11) In many severely altered settings, restoration of hydrological processes is possible in decades or less, whereas restoration of biodiversity and biogeochemical processes requires longer timescales. (12) Biogeochemical properties impart thresholds or tipping points beyond which rapid and irreversible losses of ecosystem health, function, and services can occur.
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Solution conformation of gramicidin S: An intramolecular nuclear Overhauser effect study. Proc Natl Acad Sci U S A 2010; 78:672-5. [PMID: 16592969 PMCID: PMC319861 DOI: 10.1073/pnas.78.2.672] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The solution conformation of gramicidin S in deuterated dimethyl sulfoxide was investigated by using the intramolecular nuclear Overhauser effect experiment. Experimental Overhauser enhancements were compared with predicted values for each of the nine most-stable conformations (M1-M9) calculated by Dygert et al. on the basis of energy-minimization procedures [Dygert, M., Gō, N. & Scheraga, H. A. (1975) Macromolecules 8, 750-761]. By using statistical hypothesis testing, the three lowest-energy conformations (M1, M2, and M3) were shown to give the best fit with the experimental data. All other conformations (M4-M9) were found to be inconsistent with the experimental data.
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Determination of the complete amino acid sequence of bovine neurophysin II. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 2009; 6:1-12. [PMID: 4851330 DOI: 10.1111/j.1399-3011.1974.tb02352.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Symmetrical disulfide bonds as S-protecting groups and their cleavage by dithiothreitol: synthesis of oxytocin with high biological activity. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 2009; 5:283-8. [PMID: 4759570 DOI: 10.1111/j.1399-3011.1973.tb03463.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Oxytocin analogs with substitutions in postions 3 and 4. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 2009; 7:171-8. [PMID: 1140889 DOI: 10.1111/j.1399-3011.1975.tb02429.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Synthesis and biological properties are reported for some analogs of oxytocin with replacements of the isoleucine residue in position 3, i.e., (3-proline)oxytocin and(3-D-alanine)oxytocin, and the glutamine residue in position 4, i.e., (4-D-alanine)-oxytocin and (4-D-leucin)oxytocin. (3-Proline)oxytocin exhibited smaller than0.02 U/MG oxytocic activity, 0.005 plus or minus smaller than 0.001 U/mg rat pressor activity and 0.003 plus or minus 0.0001 U/mg antidiuretic activity. (3-D-Alanine)oxytocin had no agonistic activity in the bioassays tested except for the rat antidiuretic assay (smaller than 0.0005 U/mg). The 4-D-alanine analog showed 0.05 plus or minus 0.003 U/mg oxytocic activity, 0.07 plus or minus 0.01 U/mg avian vasodepressor activity, and smaller than 0.001 U/mg rat antidiuretic activity. (4-D-Leucine)oxytocin possessed 0.001 plus or minus U/mg rat pressor activity, and showed slight inhibitory properties in the oxytocic and avian vasodepressor assays, inhibiting the oxytocin response in the latter assay by about 60% at a girnibe-to-analog ratio of 1:5000. The activity profiles of the analogs are compared to that of oxytocin and are discussed on the basis of the proposed solution conformation of oxytocin.
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Effects of natural cross-linkers on the stability of dentin collagen and the inhibition of root caries in vitro. Caries Res 2008; 42:263-8. [PMID: 18523385 DOI: 10.1159/000135671] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Accepted: 03/13/2008] [Indexed: 11/19/2022] Open
Abstract
PURPOSE To evaluate the effects of dentin collagen modifications induced by various cross-linkers on the stability of collagen matrix and the inhibition of root caries. MATERIALS AND METHODS The following cross-linkers were tested: 5% glutaraldehyde (GA), 0.5% proanthocyanidin (PA), 0.625% genipin (GE). In the first experiment, cross-linker-treated demineralized human root dentin was digested with bacterial collagenase, centrifuged, and the supernatants were subjected to amino acid analysis to determine collagen content. The residues were analyzed by SDS-PAGE and hydroxyproline analysis. In the second experiment, bovine root surfaces were conditioned with phosphoric acid, treated with the cross-linkers, incubated with Streptococcus mutans and Lactobacillus acidophilus for 1 week and the root caries inhibition was evaluated with confocal microscopy. Lastly, the ability of the bacteria to colonize the root surface was evaluated. In this experiment slabs of bovine root were treated with the cross-linkers and incubated in a suspension of S. mutans and L. acidophilus. The slabs were washed, resuspended in water, glucose was added, and the pH measured. RESULTS While all collagen was digested with collagenase in the control groups, only a small proportion was solubilized in the GA-, PA-, and GE-treated groups. The root caries was significantly inhibited by treatment with PA or GA. Drops in pH in the cross-linker-treated groups were essentially the same as in the untreated group. CONCLUSION Naturally occurring cross-linkers, especially PA, could be used to modify root dentin collagen to efficiently stabilize collagen and to increase its resistance against caries.
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Chronic Intracortical EEG Recordings in the Diagnosis and Treatment of ‘Partial’ Epilepsies. Stereotact Funct Neurosurg 2007. [DOI: 10.1159/000102746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Repeated Thoracic Discharges from a Stun Device. Acad Emerg Med 2007. [DOI: 10.1197/j.aem.2007.03.1097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Structure and thermoelasticity of irradiation grafted nano-inorganic particle filled polypropylene composites in the solid state. J MACROMOL SCI B 2007. [DOI: 10.1081/mb-120004349] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Thermophysical characterization of the deformation behavior of polyethylene/kaolin composites. J MACROMOL SCI B 2006. [DOI: 10.1080/00222349908248149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Integrating Sampling Methods for Trace Metal Analysis of Natural Water Systems: Ion Exchange Membrane Targets for Proton-Excited X-Ray Fluorescence Analysis. ANAL LETT 2006. [DOI: 10.1080/00032717208062159] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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T-kininogen can either induce or inhibit proliferation in Balb/c 3T3 fibroblasts, depending on the route of administration. Mech Ageing Dev 2005; 126:399-406. [PMID: 15664626 DOI: 10.1016/j.mad.2004.09.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Revised: 08/27/2004] [Accepted: 09/14/2004] [Indexed: 10/26/2022]
Abstract
T-kininogen (T-KG) is a precursor of T-kinin, the most abundant kinin in rat serum, and also acts as a strong and specific cysteine proteinase inhibitor. Its expression is strongly induced during aging in rats, and expression of T-KG in Balb/c 3T3 fibroblasts results in inhibition of cell proliferation. However, T-KG is a serum protein produced primarily in the liver, and thus, most cells are only exposed to the protein from the outside. To test the effect of T-KG on fibroblasts exposed to exogenous T-KG, we purified the protein from the serum of K-kininogen-deficient Katholiek rats. In contrast to the results obtained by transfection, exposure of Balb/c 3T3 fibroblasts to exogenously added T-KG leads to a dose-dependent increase in [3H]-thymidine incorporation. This response does not require kinin receptors, but it is clearly mediated by activation of the ERK pathway. As a control, we repeated the transfection experiments, using a different promoter. The results are consistent with our published data showing that, under these circumstances, T-KG inhibits cell proliferation. We conclude that T-KG exerts opposite effects on fibroblast proliferation, depending exclusively on the way that it is administered to the cells (transfection versus exogenous addition).
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Tribological behaviour of polymeric coatings. Part I. Aramid particle-reinforced epoxy nanocomposite systems. ACTA ACUST UNITED AC 2005. [DOI: 10.1002/jsl.3000210402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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The anticholinergic drug propiverine inhibits the protein kinase C activity in the rat urinary bladder. DIE PHARMAZIE 2005; 60:49-51. [PMID: 15700778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
UNLABELLED There is ample evidence that non-cholinergic protein kinase C (PKC) mediated signal transduction pathways are involved into regulation of bladder smooth muscle contractions. To evaluate whether the anticholinergic and calcium modulating drug propiverine exerts intracellular effects by inhibition of the PKC, male inbred LEW 1A rats were pretreated with 0.6, 2, 6 and 60 mg/kg body weight for 5 days. Furthermore, competition assays with partially purified PKC were performed with propiverine in vitro. The activities of the membrane-bound and soluble PKC were assessed by 32P enrichment of lysine-rich histone. RESULTS The active, membrane-bound PKC decreased by about 60% accompanied by increase of the soluble form after propiverine in doses above 0.6 mg/kg. 100 nM of the drug inhibited the PKC also in vitro whereas the propiverine metabolites M5 and M6 and atropine were without any effect. CONCLUSIONS Propiverine was identified to be an inhibitor of the protein kinase C. Its contribution to the noncholinergic control of hyperactive detrusor smooth muscle cells needs further investigation.
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Compact sources as the origin of the soft γ-ray emission of the Milky Way. Nature 2004; 428:293-6. [PMID: 15029189 DOI: 10.1038/nature02407] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2003] [Accepted: 02/10/2004] [Indexed: 11/09/2022]
Abstract
The Milky Way is known to be an abundant source of gamma-ray photons, now determined to be mainly diffuse in nature and resulting from interstellar processes. In the soft gamma-ray domain, point sources are expected to dominate, but the lack of sensitive high-resolution observations did not allow for a clear estimate of the contribution from such sources. Even the best imaging experiment revealed only a few point sources, accounting for about 50% of the total Galactic flux. Theoretical studies were unable to explain the remaining intense diffuse emission. Investigating the origin of the soft gamma-rays is therefore necessary to determine the dominant particle acceleration processes and to gain insights into the physical and chemical equilibrium of the interstellar medium. Here we report observations in the soft gamma-ray domain that reveal numerous compact sources. We show that these sources account for the entirety of the Milky Way's emission in soft gamma-rays, leaving at most a minor role for diffuse processes.
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Blood viscosity and platelet function in patients with obstructive sleep apnea syndrome treated with nasal continuous positive airway pressure. Clin Hemorheol Microcirc 2003; 27:201-7. [PMID: 12454377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Abstract
Patients with obstructive sleep apnea syndrome (OSA) have a high incidence of cardiovascular events. We measured whole blood viscosity at high (94.5 s(-1)) and low (0.1 s(-1)) shear rate, hematocrit, fibrinogen, and platelet hemostatic function (PTA-100) at 7-8 p.m. and 7-8 a.m. in 8 controls and 13 patients, once with the established nasal continuous positive airway pressure (NCPAP) treatment and once without. OSA patients had a higher plasma viscosity (1.37+/-0.11 vs. 1.19+/-0.11 mPa.s in the evening, p<0.05) and fibrinogen (2.61+/-0.49 vs. 2.11+/-0.29 g/l, p<0.05) than controls, without diurnal difference, and similar values with or without NCPAP. Whole blood viscosity and hematocrit were similar in controls and patients before and after a night with or without NCPAP. Platelet activity was significantly higher in the morning than in the evening in controls and patients with or without NCPAP. We conclude that blood viscosity and platelet activity are similar in controls and patients with OSA on a long-term treatment with NCPAP, which is not worsened by a single night without NCPAP. The increase of plasma viscosity and fibrinogen in OSA patients as well as the general increase of platelet aggregation in the morning may contribute to the increased incidence of cardiovascular events.
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Influence of propiverine on hepatic microsomal cytochrome p450 enzymes in male rats. Drug Metab Dispos 2003; 31:714-7. [PMID: 12756202 DOI: 10.1124/dmd.31.6.714] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The bladder spasmolytics propiverine was shown to induce hepatic cytochrome P450 (P450) and aminopyrine and aniline oxidation in rats. To characterize the type of enzyme induction and its dose dependence, activities of seven hepatic microsomal P450-dependent monooxygenases were measured in 72 male LEW1A albino rats (body weight 236-295 g) after oral treatment with 0.5, 2, 6, and 60 mg/kg of propiverine hydrochloride for 5 days and compared with the effects of 40 mg/kg beta-naphthoflavone, 10 mg/kg phenobarbital, and 20 mg/kg dexamethasone (each group, n = 8). CYP2B expression was measured by Western blotting. Furthermore, the inhibitory potency of propiverine on P450 enzymes was evaluated in competition assays with three most specific monooxygenases. Results show that Propiverine induced several monooxygenases and CYP2B expression dose dependently. The effects were well comparable with a phenobarbital-type inducer with 60 mg/kg being equipotent to 10 mg/kg phenobarbital. Furthermore, propiverine in low concentrations inhibited pentylresorufin O-dealkylase (for CYP2B) in vitro. In conclusion, propiverine is a phenobarbital-type inducer on hepatic P450 enzymes in rats in doses about 100-times above the therapeutic doses in man.
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Network viscoelastic behavior in poly(ethylene oxide) melts: Effects of temperature and dissolved LiClO4 on network structure and dynamic behavior. J Chem Phys 2002. [DOI: 10.1063/1.1481059] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Influence of prestorage leucocyte depletion and storage time on rheologic properties of erythrocyte concentrates. Vox Sang 2002; 82:191-7. [PMID: 12047513 DOI: 10.1046/j.1423-0410.2002.00167.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND AND OBJECTIVES Rheological blood properties were studied during storage. MATERIALS AND METHODS Blood viscosity, erythrocyte morphology and ATP levels were determined in filtered samples (Leukotrap WB filter system) and their unfiltered counterparts during storage with saline-adenine-glucose-mannitol (SAG-M) for 42 days. RESULTS Prestorage leucocyte depletion decreased blood viscosity at a high shear rate and reduced the degree of anisocytosis of erythrocytes. During storage, erythrocytes underwent a time-dependent echinocytic shape transformation, which increased the suspension viscosity at high and low shear rates. On day 42, high shear viscosity in filtered units remained lower than in unfiltered counterparts, the mean cellular volume and red blood cell distribution width (RDW) were lower and erythrocytic ATP levels were higher. CONCLUSIONS Prestorage leucocyte depletion by Leukotrap WB filters improves biophysical properties of erythrocyte concentrates throughout storage, which is, however, outweighed by a time-dependent echinocytic shape transformation and deterioration of these properties.
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Abstract
By using synthetic protease inhibitors, several investigators have demonstrated that cysteine proteinases are required for cell proliferation. Kininogens are potent and specific physiological inhibitors of cysteine proteinases. We have used several mouse fibroblast-derived cell lines that express biologically active T-kininogen under the control of the mouse metallothionein promoter to test its effect on cell proliferation. Our results indicate that expression of T-kininogen results in diminished proliferative capacity, as measured by reduced cell numbers, both in logarithmically growing cultures and in G(0) cells induced to proliferate in response to serum. Furthermore, both fluorescence-activated cell sorting (FACS) analysis and incorporation of radioactive precursors into DNA suggest that the cells are unable to progress from G(0) through the S phase of the cell cycle in response to serum stimulation. However, we find that T-kininogen-expressing cell lines are still capable of responding to growth factors present in the serum, both by activating the ERK pathway and by expressing early genes, such as c-Fos and c-Jun. Thus, our results suggest that inhibition of cysteine proteinases by T-kininogen leads to inhibition of cell proliferation between the G(1) and S phases of the cell cycle.
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No influence of C-peptide, insulin, and glucagon on blood viscosity in vitro in healthy humans and patients with diabetes mellitus. Clin Hemorheol Microcirc 2001; 24:65-74. [PMID: 11381181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
The influence of the hormones most involved in glucose homeostasis, C-peptide, insulin and glucagon on blood viscosity was tested in vitro. Whole blood (adjusted to haematocrit 45%) from healthy volunteers (n=24) and patients with diabetes mellitus (n=17) was incubated with 10(-7)-10(-10) M C-peptide, insulin or glucagon. None of these peptide hormones, neither at physiological nor at supraphysiological levels, had an influence on high (94.5 s(-1)) or low (0.1 s(-1)) shear rate viscosity. The small group of diabetic patients had a higher plasma viscosity and increased blood viscosity at 94.5 s(-1), which is in agreement with earlier studies, but decreased viscosity at low shear rate. We conclude that C-peptide, insulin and glucagon have no direct effect on blood viscosity in vitro. It is, therefore, unlikely that microvascular disturbances seen with either deficiency or excess of these hormones is due to haemorheological factors.
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Abstract
Vascular endothelial growth factor (VEGF) is an endothelial cell mitogen and permeability factor that is inducible by hypoxia. Its contribution to high-altitude illness in man is unknown. We measured VEGF levels in 14 mountaineers at low altitude (490 m) and 24 h after their arrival at high altitude (4,559 m). At high altitude, VEGF increased from [mean (SEM)] 32.5 (9.2) to 60.9 (18.5) pg.ml(-1) (P < 0.004) in the arterial blood, and from 15.9 (2.9) to 49.3 (15.9) pg.ml(-1) (P= 0.0001) in the mixed venous blood. Whereas at low altitude venous and arterial VEGF levels were not statistically different from each other (P= 0.065), the VEGF concentration was significantly lower in venous than in arterial blood samples at high altitude (P=0.004). The pulmonary capillary VEGF concentration remained unchanged at high altitude [14.8 (2.5) vs 17.1 (5.4) pg.ml(-1), P=0.85]. VEGF levels in the nine mountaineers who developed symptoms of acute mountain sickness (AMS), and in the six subjects who had radiographic evidence of high-altitude pulmonary edema were similar to those in subjects without symptoms. VEGF was not correlated with either AMS scores, mean pulmonary arterial pressures, arterial partial pressure of O2, or alveolar-arterial O2 gradients. We conclude that VEGF release is stimulated at high altitude, but that VEGF is probably not related to high-altitude illness.
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Epistemology at work: the ontological relationship between feminist methods, intersubjectivity and nursing research--a research exemplar. Contemp Nurse 2001; 10:265-72. [PMID: 11855122 DOI: 10.5172/conu.10.3-4.265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This article explores the importance of strong epistemological and ontological links in nursing research by examining the design and process of a recent research project. The research topic concerns the relationship between self-concept and nursing practice. In this article, the authors demonstrate that commitment to a methodologically consistent process and the necessary associated epistemological and ontological positions provides a depth and structure to nursing research. It is the authors' belief that such consistency within research acts to strengthen the research process, and consequently strengthens nursing's research base and knowledge.
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