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1.
Nature ; 622(7982): 301-307, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37648861

ABSTRACT

According to twenty-first century climate-model projections, greenhouse warming will intensify rainfall variability and extremes across the globe1-4. However, verifying this prediction using observations has remained a substantial challenge owing to large natural rainfall fluctuations at regional scales3,4. Here we show that deep learning successfully detects the emerging climate-change signals in daily precipitation fields during the observed record. We trained a convolutional neural network (CNN)5 with daily precipitation fields and annual global mean surface air temperature data obtained from an ensemble of present-day and future climate-model simulations6. After applying the algorithm to the observational record, we found that the daily precipitation data represented an excellent predictor for the observed planetary warming, as they showed a clear deviation from natural variability since the mid-2010s. Furthermore, we analysed the deep-learning model with an explainable framework and observed that the precipitation variability of the weather timescale (period less than 10 days) over the tropical eastern Pacific and mid-latitude storm-track regions was most sensitive to anthropogenic warming. Our results highlight that, although the long-term shifts in annual mean precipitation remain indiscernible from the natural background variability, the impact of global warming on daily hydrological fluctuations has already emerged.


Subject(s)
Climate Models , Deep Learning , Global Warming , Human Activities , Neural Networks, Computer , Rain , Temperature , Weather , Tropical Climate , Pacific Ocean , Hydrology , Global Warming/statistics & numerical data
2.
Nature ; 573(7775): 568-572, 2019 09.
Article in English | MEDLINE | ID: mdl-31534218

ABSTRACT

Variations in the El Niño/Southern Oscillation (ENSO) are associated with a wide array of regional climate extremes and ecosystem impacts1. Robust, long-lead forecasts would therefore be valuable for managing policy responses. But despite decades of effort, forecasting ENSO events at lead times of more than one year remains problematic2. Here we show that a statistical forecast model employing a deep-learning approach produces skilful ENSO forecasts for lead times of up to one and a half years. To circumvent the limited amount of observation data, we use transfer learning to train a convolutional neural network (CNN) first on historical simulations3 and subsequently on reanalysis from 1871 to 1973. During the validation period from 1984 to 2017, the all-season correlation skill of the Nino3.4 index of the CNN model is much higher than those of current state-of-the-art dynamical forecast systems. The CNN model is also better at predicting the detailed zonal distribution of sea surface temperatures, overcoming a weakness of dynamical forecast models. A heat map analysis indicates that the CNN model predicts ENSO events using physically reasonable precursors. The CNN model is thus a powerful tool for both the prediction of ENSO events and for the analysis of their associated complex mechanisms.


Subject(s)
Deep Learning , El Nino-Southern Oscillation , Forecasting/methods , Models, Statistical , Temperature
3.
Inorg Chem ; 63(1): 537-547, 2024 Jan 08.
Article in English | MEDLINE | ID: mdl-38108625

ABSTRACT

In this article, we discuss the synthesis of eight novel zirconium and hafnium complexes containing amidoxime ligands as potential precursors for atomic layer deposition (ALD). Two amidoximes, viz., (E)-N'-hydroxy-N,N-dimethylacetimidamide (mdaoH) and (Z)-N'-hydroxy-N,N-dimethylpivalimidamide (tdaoH), along with their Zr and Hf homoleptic complexes, Zr(mdao)4 (1), Hf(mdao)4 (2), Zr(tdao)4 (3), and Hf(tdao)4 (4) were prepared. We further synthesized heteroleptic compounds with different physical properties by introducing cyclopentadienyl (Cp) ligand, namely, CpZr(mdao)3 (5), CpHf(mdao)3 (6), CpZr(tdao)3 (7), and CpHf(tdao)3 (8). Thermogravimetric analysis was used for the assessment of the evaporation characteristics of complexes 1, 2, 5, and 6, and it revealed multistep weight losses with high residues. On the other hand, the thermogravimetric analysis curves of complexes 3, 4, 7, and 8 comprising tdao ligands revealed single-step weight losses with moderate residues. Single-crystal X-ray diffraction studies of complexes 1, 3, and 7 showed that all of the complexes have monomeric molecular structures. Complex 7 exhibited a low melting point (75 °C), good volatility, and high thermal stability compared with other complexes. Therefore, an atomic layer deposition process for the growth of ZrO2 was developed by using ZrCp(tdao)3 (7) as a novel precursor.

4.
Helicobacter ; 28(4): e12998, 2023 Aug.
Article in English | MEDLINE | ID: mdl-37293999

ABSTRACT

BACKGROUND/AIMS: In areas with >15% clarithromycin resistance, bismuth-based quadruple therapy is recommended for first-line Helicobacter pylori eradication. This study aimed to determine the efficacy of the twice-daily intake of bismuth-based quadruple therapy among 10-day, 14-day, and half-dose antibiotic regimens. METHODS: From May 2021 to March 2023, H. pylori-infected Korean adults were administered tetracycline (1 g), metronidazole (750 mg), bismuth potassium citrate (300 mg), and lansoprazole (30 mg) twice daily, after breakfast and dinner, for 10 days. The regimen was administered for 14 days if the body weight was ≥70 kg or if the patient had reinfection. Half doses of antibiotics were administered for 14 days if there was a risk of drug interactions or if the patient was aged ≥75 years. The 13 C-urea breath test was performed after 6 weeks. RESULTS: Among the 1258 infected Koreans, 85.1% (412/484) in the 10-day, 84.3% (498/591) in the 14-day, and 86.3% (158/183) in the half-dose antibiotic groups followed the instructions. In the per-protocol (PP) analysis, eradication rates were higher in the 10-day (90.5%, p = 0.019) and 14-day (90.2%, p = 0.023) groups than in the half-dose group (83.5%). In the intention-to-treat (ITT) analysis, eradication rates were higher in the 10-day group (80.6%) than in the half-dose group (73.2%, p = 0.039). In the half-dose group, the eradication rate was lower in patients aged ≥75 years (PP: 74.6%, ITT: 66.2%) than in those with a risk of drug interactions (PP: 89.7% [p = 0.017], ITT: 82.4% [p = 0.019]). CONCLUSIONS: Twice-daily intake of bismuth-based quadruple therapy for 10-14 days showed an eradication rate of >90% in the PP analysis. A 10-day regimen could be administered to eradication-naive patients with a body weight below 70 kg. A half-dose antibiotic regimen might be recommended to patients with a risk of drug interactions but not to those aged ≥75 years simply due to old age.


Subject(s)
Helicobacter Infections , Helicobacter pylori , Adult , Humans , Bismuth , Retrospective Studies , Helicobacter Infections/drug therapy , Drug Therapy, Combination , Anti-Bacterial Agents , Metronidazole , Amoxicillin , Treatment Outcome
5.
Vasc Med ; 28(3): 188-196, 2023 06.
Article in English | MEDLINE | ID: mdl-36597615

ABSTRACT

INTRODUCTION: Poor quality neighborhood environments are independent risk factors for cardiovascular disease (CVD) but are understudied in Black adults, who face large CVD health disparities. Arterial stiffness, a marker of early vascular aging, precedes development of hypertension and adverse CVD events but the effect of neighborhood on arterial stiffness among Black adults remains unknown. OBJECTIVE: We compared the association between neighborhood environment and arterial stiffness among Black adults in Jackson, MS and Atlanta, GA. METHODS: We studied 1582 Black adults (mean age 53 ± 10, 35% male) living in Jackson, MS from the Jackson Heart Study (JHS) and 451 Black adults (mean age 53 ± 10, 39% male) living in Atlanta, GA from the Morehouse-Emory Cardiovascular Center for Health Equity (MECA) study, without known CVD. Neighborhood problems (includes measures of aesthetic quality, walking environment, food access), social cohesion (includes activity with neighbors), and violence/safety were assessed using validated questionnaires. Arterial stiffness was measured as pulse wave velocity (PWV) using magnetic resonance imaging in JHS and as PWV and augmentation index (AIx) using applanation tonometry (SphygmoCor, Inc.) in MECA. Multivariable linear regression models were used to examine the association between neighborhood characteristics and arterial stiffness, adjusting for potential confounders. RESULTS: Improved social characteristics, measured as social cohesion in JHS (ß = -0.32 [-0.63, -0.02], p = 0.04) and activity with neighbors (ß = -0.23 [-0.40, -0.05], p = 0.01) in MECA, were associated with lower PWV in both cohorts and lower AIx (ß = -1.74 [-2.92, - 0.56], p = 0.004) in MECA, after adjustment for CVD risk factors and income. Additionally, in MECA, better food access (ß = -1.18 [-2.35, - 0.01], p = 0.05) was associated with lower AIx and, in JHS, lower neighborhood problems (ß = -0.33 [-0.64, - 0.02], p = 0.04) and lower violence (ß = -0.30 [-0.61, 0.002], p = 0.05) were associated with lower PWV. CONCLUSION: Neighborhood social characteristics show an independent association with the vascular health of Black adults, findings that were reproducible in two distinct American cities.


Subject(s)
Cardiovascular Diseases , Health Equity , Vascular Stiffness , Humans , Adult , Male , Middle Aged , Female , Pulse Wave Analysis , Longitudinal Studies , Cardiovascular Diseases/diagnosis , Cardiovascular Diseases/epidemiology , Risk Factors , Neighborhood Characteristics
6.
Am J Otolaryngol ; 44(4): 103878, 2023.
Article in English | MEDLINE | ID: mdl-37058908

ABSTRACT

OBJECTIVES: Pediatric idiopathic sudden hearing loss (PISSNHL) is a rare disease with no established factor affecting its prognosis. In this study, we investigate the risk factors affecting the prognosis of PISSNHL. MATERIAL AND METHODS: Among the patients who visited our hospital from January 2010 to December 2021, the characteristics associated prognosis of 54 patients with unilateral PISSNHL were retrospectively confirmed. RESULTS: Patients' recovery was determined by applying Siegel's criteria (SC) and AAO-HNS criteria (AC). Twenty-seven (50 %) and 29 patients (54.3 %) recovered for SC and AC, respectively. Age, sex, side, duration between onset and treatment, administration of intra-tympanic steroid injection, accompanying symptoms (tinnitus and dizziness), BMI, serum creatinine level, neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte count (PLR), lymphocyte count, and platelet count were not significantly different between the recovery group and the poor recovery group (P > 0.05). The patients were divided into five groups according to the initial hearing of the affected ear and again according to their audiogram type. The initial hearing levels, hearing level severity, and the audiogram type were significantly different between the deaf group (>100 dB HL) and the non-deaf group (P < 0.05). CONCLUSION: The prognosis of PISSNHL is closely related to the initial hearing at the onset. If the initial hearing level is <100 dB, the recovery rate is approximately 50 %, therefore requiring active treatment and emotional support. It may also be related to the type of audiometric curve.


Subject(s)
Hearing Loss, Sensorineural , Hearing Loss, Sudden , Humans , Child , Hearing Loss, Sudden/diagnosis , Hearing Loss, Sudden/drug therapy , Hearing Loss, Sudden/etiology , Retrospective Studies , Prognosis , Hearing , Hearing Loss, Sensorineural/diagnosis , Hearing Loss, Sensorineural/etiology , Hearing Loss, Sensorineural/therapy , Risk Factors
7.
Sensors (Basel) ; 23(10)2023 May 09.
Article in English | MEDLINE | ID: mdl-37430512

ABSTRACT

Although research into ultrahigh dose-rate (UHDR) radiation therapy is ongoing, there is a significant lack of experimental measurements for two-dimensional (2D) dose-rate distributions. Additionally, conventional pixel-type detectors result in significant beam loss. In this study, we developed a pixel array-type detector with adjustable gaps and a data acquisition system to evaluate its effectiveness in measuring UHDR proton beams in real time. We measured a UHDR beam at the Korea Institute of Radiological and Medical Sciences using an MC-50 cyclotron, which produced a 45-MeV energy beam with a current range of 10-70 nA, to confirm the UHDR beam conditions. To minimize beam loss during measurement, we adjusted the gap and high voltage on the detector and determined the collection efficiency of the developed detector through Monte Carlo simulation and experimental measurements of the 2D dose-rate distribution. We also verified the accuracy of the real-time position measurement using the developed detector with a 226.29-MeV PBS beam at the National Cancer Center of the Republic of Korea. Our results indicate that, for a current of 70 nA with an energy beam of 45 MeV generated using the MC-50 cyclotron, the dose rate exceeded 300 Gy/s at the center of the beam, indicating UHDR conditions. Simulation and experimental measurements show that fixing the gap at 2 mm and the high voltage at 1000 V resulted in a less than 1% loss of collection efficiency when measuring UHDR beams. Furthermore, we achieved real-time measurements of the beam position with an accuracy of within 2% at five reference points. In conclusion, our study developed a beam monitoring system that can measure UHDR proton beams and confirmed the accuracy of the beam position and profile through real-time data transmission.

8.
Nano Lett ; 22(11): 4589-4595, 2022 Jun 08.
Article in English | MEDLINE | ID: mdl-35536043

ABSTRACT

The ultrathin and continuous ruthenium (Ru) film was deposited through an improved atomic layer deposition (ALD) process with a discrete feeding method (DFM), called DF-ALD, employing a cut-in purge step during the precursor feeding. The excess precursor molecules can be physically adsorbed onto the chemisorbed precursors on the substrate during precursor feeding, which screens the reactive sites on the surface. Using DF-ALD, surface coverage of precursors was enhanced because the cut-in purge removes the physisorbed precursors securing the reactive sites beneath them; thus, nucleation density was greatly increased. Therefore, the grain size decreased, which changed the microstructure and increased oxygen impurity concentration. However, a more metallic Ru thin film was formed due to thermodynamic stability and improved physical density. Consequently, DF-ALD enables the deposition of the ultrathin (3 nm) and continuous Ru film with a low resistivity of ∼60 µΩ cm and a high effective work function of ∼4.8 eV.

9.
Molecules ; 28(3)2023 Jan 19.
Article in English | MEDLINE | ID: mdl-36770701

ABSTRACT

The term "nanosheets" has been coined recently to describe supported and free-standing "ultrathin film" materials, with thicknesses ranging from a single atomic layer to a few tens of nanometers. Owing to their physicochemical properties and their large surface area with abundant accessible active sites, nanosheets (NSHs) of inorganic materials such as Au, amorphous carbon, graphene, and boron nitride (BN) are considered ideal building blocks or scaffolds for a wide range of applications encompassing electronic and optical devices, membranes, drug delivery systems, and multimodal contrast agents, among others. A wide variety of synthetic methods are employed for the manufacturing of these NSHs, and they can be categorized into (1) top-down approaches involving exfoliation of layered materials, or (2) bottom-up approaches where crystal growth of nanocomposites takes place in a liquid or gas phase. Of note, polymer template liquid exfoliation (PTLE) methods are the most suitable as they lead to the fabrication of high-performance and stable hybrid NSHs and NSH composites with the appropriate quality, solubility, and properties. Moreover, PTLE methods allow for the production of stimulus-responsive NSHs, whose response is commonly driven by a favorable growth in the appropriate polymer chains onto one side of the NSHs, resulting in the ability of the NSHs to roll up to form nanoscrolls (NSCs), i.e., open tubular structures with tunable interlayer gaps between their walls. On the other hand, this review gives insight into the potential of the stimulus-responsive nanostructures for biosensing and controlled drug release systems, illustrating the last advances in the PTLE methods of synthesis of these nanostructures and their applications.

11.
Vasc Med ; 27(1): 13-20, 2022 02.
Article in English | MEDLINE | ID: mdl-34549642

ABSTRACT

Arterial stiffness is a precursor for the development of hypertension and premature cardiovascular disease (CVD). Physical activity has been associated with lower arterial stiffness among largely White populations, but the types of activity required and whether these findings apply to Black adults remain unknown. We examined whether physical activity levels were associated with arterial stiffness among Black adults in two independent cohorts. In the Morehouse-Emory Cardiovascular (MECA) Center for Health Equity, 378 Black adults (age 52.8 ± 10.3, 39.7% male) without known CVD living in Atlanta, GA were recruited. Arterial stiffness was measured as pulse wave velocity (PWV). Total and domain-specific physical activity were assessed by self-report. Multiple linear regression models were used to investigate differences across physical activity levels after adjusting for age, sex, CVD risk factors, and socioeconomic status. Findings were validated in an independent cohort of Black adults (n = 55, age 50.4 ± 9.2, 23.6% male). After adjustment for covariates, lower arterial stiffness was associated with higher self-reported levels of sport/exercise (6.92 ± 1.13 vs 7.75 ± 1.14, p < 0.001, highest vs lowest quartile) and home/life activities (7.34 ± 1.24 vs 7.73 ± 1.07, p = 0.04, highest vs lowest quartile), but not work, active living, or the overall physical activity scores. These findings were replicated in the independent cohort where higher levels of sport/exercise remained associated with lower arterial stiffness (6.66 ± 0.57 vs 8.21 ± 0.66, p < 0.001, highest vs lowest quartile). Higher levels of sport/exercise and home/life-related physical activities (in comparison to occupational physical activity) are associated with lower arterial stiffness in Black adults.


Subject(s)
Cardiovascular Diseases , Hypertension , Vascular Stiffness , Adult , Cardiovascular Diseases/diagnosis , Cardiovascular Diseases/epidemiology , Exercise , Female , Humans , Hypertension/diagnosis , Hypertension/epidemiology , Male , Pulse Wave Analysis , Risk Factors
12.
Dig Dis Sci ; 67(12): 5602-5609, 2022 12.
Article in English | MEDLINE | ID: mdl-35384623

ABSTRACT

BACKGROUND /AIMS: The serum pepsinogen (PG) assay is used to screen subjects at high risk for gastric cancer. Currently, there are few studies on the PG levels for the detection of Helicobacter pylori infection. This study aimed to determine the PG assay findings for detecting ongoing infection. METHODS: Asymptomatic subjects who underwent a 13C-urea breath test (13C-UBT) on the day of gastroscopy and serum assay for cancer screening were included. Subjects with a recent intake of acid suppressants or antibiotics, gastrectomy, or renal failure were excluded. H. pylori infection was defined as a positive 13C-UBT result. RESULTS: Among the 500 included subjects, 167 (33.4%) had current infection. The serum PG II levels of > 12.95 ng/mL (area under the curve [AUC] = 0.930, sensitivity 86.5%, specificity 90.7%) and PG I/II ratios of < 4.35 (AUC = 0.875, sensitivity 86.8%, specificity 79.6%) were related to infection. The PG I/II ratios were inversely correlated with age (r = -0.160, p = 0.039). The cutoff values of PG I/II ratios were lower in older subjects aged ≥ 50 years (< 4.05; AUC = 0.875, sensitivity 80.7%, specificity 88.2%) than in younger subjects aged < 50 years (< 4.35; AUC = 0.873, sensitivity 77.4%, specificity 88.9%). CONCLUSIONS: Serum PG II levels > 12.95 ng/mL and PG I/II ratios < 4.35 suggest ongoing infection in asymptomatic subjects; therefore, H. pylori confirmation tests (i.e., 13C-UBT) should be considered under these conditions. Stricter criteria are required in older subjects aged ≥ 50 years (PG I/II ratio < 4.05) to detect ongoing infection than younger subjects.


Subject(s)
Helicobacter Infections , Helicobacter pylori , Humans , Aged , Pepsinogen A , Helicobacter Infections/diagnosis , Cross-Sectional Studies , Urea , Pepsinogen C , Breath Tests
13.
EMBO J ; 36(4): 520-535, 2017 02 15.
Article in English | MEDLINE | ID: mdl-28028053

ABSTRACT

Yes-associated protein (YAP) and myocardin-related transcription factor (MRTF) play similar roles and exhibit significant crosstalk in directing transcriptional responses to chemical and physical extracellular cues. The mechanism underlying this crosstalk, however, remains unclear. Here, we show MRTF family proteins bind YAP via a conserved PPXY motif that interacts with the YAP WW domain. This interaction allows MRTF to recruit NcoA3 to the TEAD-YAP transcriptional complex and potentiate its transcriptional activity. We show this interaction of MRTF and YAP is critical for LPA-induced cancer cell invasion in vitro and breast cancer metastasis to the lung in vivo We also demonstrate the significance of MRTF-YAP binding in regulation of YAP activity upon acute actin cytoskeletal damage. Acute actin disruption induces nucleo-cytoplasmic shuttling of MRTF, and this process underlies the LATS-independent regulation of YAP activity. Our results provide clear evidence of crosstalk between MRTF and YAP independent of the LATS kinases that normally act upstream of YAP signaling. Our results also suggest a mechanism by which extracellular stimuli can coordinate physiological events downstream of YAP.


Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , DNA-Binding Proteins/metabolism , Neoplasm Metastasis , Nuclear Proteins/metabolism , Phosphoproteins/metabolism , Trans-Activators/metabolism , Transcription Factors/metabolism , Transcription, Genetic , Animals , Cell Line , Disease Models, Animal , Female , Humans , Lung/pathology , Lung Neoplasms/pathology , Mice, Inbred BALB C , Nuclear Receptor Coactivator 3/metabolism , Protein Binding , Protein Multimerization , TEA Domain Transcription Factors , YAP-Signaling Proteins
14.
Catheter Cardiovasc Interv ; 97(1): E161-E167, 2021 01 01.
Article in English | MEDLINE | ID: mdl-32569445

ABSTRACT

OBJECTIVES: To understand the predictors of survival and indications for Impella RP in a single healthcare experience. BACKGROUND: The Impella RP can be used to temporarily support patients with right ventricular (RV) dysfunction after left ventricular assist device (LVAD) placement or myocardial infarction (MI). However, recent postmarket approval data have raised concerns of higher than expected mortality with this device. METHODS: A retrospective chart review and analysis of all patients that underwent Impella RP placement in the Emory Healthcare system between January 2016 and December 2018 were performed. Patients were classified according to the indication. RESULTS: A total of 39 patients underwent Impella RP placement. Six patients were post-LVAD, 9 were implanted for massive pulmonary embolism with persistent shock, 8 for postcardiac surgery RV failure (non-LVAD), 11 for RV failure post-MI, and 5 for new or worsening nonischemic cardiomyopathy. The worst survival was noted in MI-related cardiogenic shock group and in patients who presented with cardiac arrest (3/12). All observed deaths were due to persistent refractory shock. There was no device related death. Survival improved during the last year of experience compared to the first 2 years. CONCLUSION: This study supports the selective use of the Impella RP, with a higher than national reported survival rate (49% vs. 28.6%). Indication appears to be an important factor determining survival.


Subject(s)
Heart-Assist Devices , Delivery of Health Care , Heart-Assist Devices/adverse effects , Humans , Retrospective Studies , Shock, Cardiogenic/diagnosis , Shock, Cardiogenic/etiology , Shock, Cardiogenic/therapy , Treatment Outcome
15.
Circ Res ; 125(10): 874-883, 2019 10 25.
Article in English | MEDLINE | ID: mdl-31550998

ABSTRACT

RATIONALE: Excessive vasoconstriction in response to mental stress may be a potential mechanism by which acute psychological stress leads to adverse cardiac events. OBJECTIVES: We investigated whether excessive digital vasoconstriction during acute mental stress predicts adverse cardiovascular outcomes among patients with coronary artery disease. METHODS AND RESULTS: Five hundred forty-nine patients with stable coronary artery disease (age 63±9, 76% male, 29% black) underwent mental stress testing with a standardized public speaking stressor and followed prospectively for cardiovascular end points. Digital pulse wave amplitude was continuously measured using peripheral artery tonometry (PAT, Itamar Inc). Stress/rest PAT ratio (sPAT) of pulse wave amplitude during mental stress/baseline was calculated and dichotomized by the median value into low and high sPAT ratio groups. Upon 3-year follow-up, Fine and Gray's subdistribution hazard ratios were used to examine the association between sPAT ratio and the composite end point of cardiovascular death, myocardial infarction, revascularization, and hospitalization for heart failure. The median sPAT ratio was 0.68 (interquartile range, 0.48-0.88), indicating 32% vasoconstriction with mental stress. Men were more likely to have low sPAT ratio than women (odds ratio, 1.79; P=0.007) while those on ß-blockers were less likely to have low sPAT ratio (odds ratio, 0.52; P=0.003). After adjusting for demographic and cardiovascular risk factors, medications, and rate-pressure product change during mental stress, those with low sPAT ratio were at significantly higher risk of adverse outcomes (subdistribution hazard ratio, 1.77 [95% CI, 1.12-2.80]). CONCLUSIONS: Greater peripheral vasoconstriction with mental stress, denoted by a low sPAT ratio, is associated with a higher risk of adverse cardiovascular outcomes in patients with coronary artery disease.


Subject(s)
Blood Flow Velocity/physiology , Coronary Artery Disease/physiopathology , Coronary Artery Disease/psychology , Stress, Psychological/physiopathology , Stress, Psychological/psychology , Vasoconstriction/physiology , Aged , Cohort Studies , Female , Follow-Up Studies , Humans , Male , Middle Aged , Plethysmography, Impedance/methods
16.
Inorg Chem ; 60(23): 17722-17732, 2021 Dec 06.
Article in English | MEDLINE | ID: mdl-34813316

ABSTRACT

This paper describes the synthesis of eight novel zirconium and hafnium complexes containing N-alkoxy carboxamidate-type ligands, as potential precursors for metal oxides and atomic layer deposition (ALD) for HfO2. A series of ligands, viz., N-ethoxy-2,2-dimethylpropanamide (edpaH), N-ethoxy-2-methylpropanamide (empaH), and N-methoxy-2,2-dimethylpropanamide (mdpaH), were used to afford complexes Zr(edpa)4 (1), Hf(edpa)4 (2), Zr(empa)4 (3), Hf(empa)4 (4), Zr(mdpa)4 (5), Hf(mdpa)4 (6), ZrCp(edpa)3 (7), and HfCp(edpa)3 (8). Thermogravimetric analysis curves assessed for the evaporation characteristics of complexes 1-8 revealed single-step weight losses with low residues, except for the mdpa-containing complexes. Single-crystal X-ray diffraction studies of 1, 2, 5, and 6 revealed that all the complexes have monomeric molecular structures, with the central metal ion surrounded by eight oxygen atoms from the four bidentate alkoxyalkoxide ligands. Among the complexes prepared, 8 exhibited a low melting point (64 °C), good volatility (1 Torr at 112 °C), high thermal stability, and excellent endurance over 6 weeks at 120 °C. Therefore, an ALD process for the growth of HfO2 was developed using HfCp(edpa)3 (8) as a novel precursor. Furthermore, the HfO2 film exhibited a low capacitance equivalent oxide thickness of ∼1.5 nm, with Jg as low as ∼3 × 10-4 A/cm2 at Vg -1 V in a metal-insulator-semiconductor capacitor (Au/HfO2/p-Si).

17.
JAMA ; 326(18): 1818-1828, 2021 11 09.
Article in English | MEDLINE | ID: mdl-34751708

ABSTRACT

Importance: Mental stress-induced myocardial ischemia is a recognized phenomenon in patients with coronary heart disease (CHD), but its clinical significance in the contemporary clinical era has not been investigated. Objective: To compare the association of mental stress-induced or conventional stress-induced ischemia with adverse cardiovascular events in patients with CHD. Design, Setting, and Participants: Pooled analysis of 2 prospective cohort studies of patients with stable CHD from a university-based hospital network in Atlanta, Georgia: the Mental Stress Ischemia Prognosis Study (MIPS) and the Myocardial Infarction and Mental Stress Study 2 (MIMS2). Participants were enrolled between June 2011 and March 2016 (last follow-up, February 2020). Exposures: Provocation of myocardial ischemia with a standardized mental stress test (public speaking task) and with a conventional (exercise or pharmacological) stress test, using single-photon emission computed tomography. Main Outcomes and Measures: The primary outcome was a composite of cardiovascular death or first or recurrent nonfatal myocardial infarction. The secondary end point additionally included hospitalizations for heart failure. Results: Of the 918 patients in the total sample pool (mean age, 60 years; 34% women), 618 participated in MIPS and 300 in MIMS2. Of those, 147 patients (16%) had mental stress-induced ischemia, 281 (31%) conventional stress ischemia, and 96 (10%) had both. Over a 5-year median follow-up, the primary end point occurred in 156 participants. The pooled event rate was 6.9 per 100 patient-years among patients with and 2.6 per 100 patient-years among patients without mental stress-induced ischemia. The multivariable adjusted hazard ratio (HR) for patients with vs those without mental stress-induced ischemia was 2.5 (95% CI, 1.8-3.5). Compared with patients with no ischemia (event rate, 2.3 per 100 patient-years), patients with mental stress-induced ischemia alone had a significantly increased risk (event rate, 4.8 per 100 patient-years; HR, 2.0; 95% CI, 1.1-3.7) as did patients with both mental stress ischemia and conventional stress ischemia (event rate, 8.1 per 100 patient-years; HR, 3.8; 95% CI, 2.6-5.6). Patients with conventional stress ischemia alone did not have a significantly increased risk (event rate, 3.1 per 100 patient-years; HR, 1.4; 95% CI, 0.9-2.1). Patients with both mental stress ischemia and conventional stress ischemia had an elevated risk compared with patients with conventional stress ischemia alone (HR, 2.7; 95% CI, 1.7-4.3). The secondary end point occurred in 319 participants. The event rate was 12.6 per 100 patient-years for patients with and 5.6 per 100 patient-years for patients without mental stress-induced ischemia (adjusted HR, 2.0; 95% CI, 1.5-2.5). Conclusions and Relevance: Among patients with stable coronary heart disease, the presence of mental stress-induced ischemia, compared with no mental stress-induced ischemia, was significantly associated with an increased risk of cardiovascular death or nonfatal myocardial infarction. Although these findings may provide insights into mechanisms of myocardial ischemia, further research is needed to assess whether testing for mental stress-induced ischemia has clinical value.


Subject(s)
Coronary Disease/complications , Myocardial Ischemia/psychology , Stress, Psychological/complications , Adult , Aged , Coronary Disease/mortality , Coronary Disease/psychology , Exercise Test , Female , Humans , Male , Middle Aged , Myocardial Ischemia/diagnostic imaging , Myocardial Ischemia/etiology , Myocardial Perfusion Imaging/methods , Prospective Studies , Speech , Tomography, Emission-Computed, Single-Photon
18.
Int J Mol Sci ; 22(3)2021 Jan 29.
Article in English | MEDLINE | ID: mdl-33572992

ABSTRACT

Retinal pigment epithelial (RPE) cells occupy the outer layer of the retina and perform various biological functions. Oxidative damage to RPE cells is a major risk factor for retinal degeneration that ultimately leads to vision loss. In this study, we investigated the role of spermidine in a hydrogen peroxide (H2O2)-induced oxidative stress model using human RPE cells. Our findings showed that 300 µM H2O2 increased cytotoxicity, apoptosis, and cell cycle arrest in the G2/M phase, whereas these effects were markedly suppressed by 10 µM spermidine. Furthermore, spermidine significantly reduced H2O2-induced mitochondrial dysfunction including mitochondrial membrane potential and mitochondrial activity. Although spermidine displays antioxidant properties, the generation of intracellular reactive oxygen species (ROS) upon H2O2 insult was not regulated by spermidine. Spermidine did suppress the increase in cytosolic Ca2+ levels resulting from endoplasmic reticulum stress in H2O2-stimulated human RPE cells. Treatment with a cytosolic Ca2+ chelator markedly reversed H2O2-induced cellular dysfunction. Overall, spermidine protected against H2O2-induced cellular damage by blocking the increase of intracellular Ca2+ independently of ROS. These results suggest that spermidine protects RPE cells from oxidative stress, which could be a useful treatment for retinal diseases.


Subject(s)
Apoptosis , Calcium/metabolism , Oxidative Stress , Retinal Pigment Epithelium/cytology , Spermidine/metabolism , Antioxidants/metabolism , Antioxidants/pharmacology , Apoptosis/drug effects , Cell Line , Humans , Hydrogen Peroxide/metabolism , Membrane Potential, Mitochondrial/drug effects , Oxidative Stress/drug effects , Reactive Oxygen Species/metabolism , Retinal Pigment Epithelium/drug effects , Retinal Pigment Epithelium/metabolism , Spermidine/pharmacology
19.
Gut ; 69(8): 1432-1440, 2020 08.
Article in English | MEDLINE | ID: mdl-31822581

ABSTRACT

OBJECTIVE: No population-based study has evaluated the natural course of UC over three decades in non-Caucasians. We aimed to assess the long-term natural course of Korean patients with UC in a population-based cohort. DESIGN: This Korean population-based, Songpa-Kangdong IBD cohort included all patients (n=1013) newly diagnosed with UC during 1986-2015. Disease outcomes and their predictors were evaluated. RESULTS: During the median follow-up of 105 months, the overall use of systemic corticosteroids, thiopurines and antitumour necrosis factor (anti-TNF) agents was 40.8%, 13.9% and 6.5%, respectively. Over time, the cumulative risk of commencing corticosteroids decreased, whereas that of commencing thiopurines and anti-TNF agents increased. During follow-up, 28.7% of 778 patients with proctitis or left-sided colitis at diagnosis experienced proximal disease extension. A total of 28 patients (2.8%) underwent colectomy, demonstrating cumulative risks of colectomy at 1, 5, 10, 20 and 30 years after diagnosis of 1.0%, 1.9%, 2.2%, 5.1% and 6.4%, respectively. Multivariate Cox regression analysis revealed that extensive colitis at diagnosis (HR 8.249, 95% CI 2.394 to 28.430), ever use of corticosteroids (HR 6.437, 95% CI 1.440 to 28.773) and diagnosis in the anti-TNF era (HR 0.224, 95% CI 0.057 to 0.886) were independent predictors of colectomy. The standardised mortality ratio in patients with UC was 0.725 (95% CI 0.508 to 1.004). CONCLUSION: Korean patients with UC may have a better clinical course than Western patients, as indicated by a lower colectomy rate. The overall colectomy rate has continued to decrease over the past three decades.


Subject(s)
Adrenal Cortex Hormones/therapeutic use , Colectomy/statistics & numerical data , Colitis, Ulcerative/drug therapy , Colitis, Ulcerative/surgery , Tumor Necrosis Factor-alpha/antagonists & inhibitors , Adolescent , Adult , Disease Progression , Female , Follow-Up Studies , Hospitalization/statistics & numerical data , Humans , Immunosuppressive Agents/therapeutic use , Male , Mercaptopurine/analogs & derivatives , Mercaptopurine/therapeutic use , Prognosis , Republic of Korea , Risk Factors , Severity of Illness Index , Time Factors , Young Adult
20.
Carcinogenesis ; 41(10): 1341-1352, 2020 10 15.
Article in English | MEDLINE | ID: mdl-32706861

ABSTRACT

Pathological changes in the epigenetic landscape of chromatin are hallmarks of cancer. The caudal-type homeobox gene CDX2 is not expressed in normal gastric epithelia but rather in adult intestinal epithelia, and it is overexpressed in intestinal metaplasia (IM). However, it remains unclear how CDX2 transcription is suppressed in normal gastric epithelial cells and overexpressed in IM. Here, we demonstrate that methylation of the CDX2 promoter increases with age in Helicobacter pylori-positive, noncancerous gastric tissue, whereas the promoter is demethylated in paired gastric tumors in which CDX2 is upregulated. Moreover, we also found that the CDX2 promoter is demethylated in IM as well as gastric tumor. Immunohistochemistry revealed that CDX2 is present in foci of parts of the gastric mucosae but highly expressed in IM as well as in gastric tumors, suggesting that the elevated level of CDX2 in IM and gastric tumors may be attributable to promoter demethylation. Our data suggest that CDX2 repression may be associated with promoter methylation in noncancerous H. pylori-positive mucosa but its upregulation might be attributable to increased promoter activity mediated by chromatin remodeling during gastric carcinogenesis.


Subject(s)
CDX2 Transcription Factor/genetics , DNA Demethylation , DNA Methylation , Gastric Mucosa/microbiology , Gene Expression Regulation, Neoplastic , Helicobacter pylori , Promoter Regions, Genetic , Stomach Neoplasms/genetics , Stomach Neoplasms/microbiology , Adult , Age Factors , Aged , Cell Line, Tumor , Female , Gene Silencing , Humans , Male , Middle Aged , Up-Regulation
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