The 2010 summer heat wave in western Russia was extraordinary, with the region experiencing the warmest July since at least 1880 and numerous locations setting all‐time maximum temperature records. ...This study explores whether early warning could have been provided through knowledge of natural and human‐caused climate forcings. Model simulations and observational data are used to determine the impact of observed sea surface temperatures (SSTs), sea ice conditions and greenhouse gas concentrations. Analysis of forced model simulations indicates that neither human influences nor other slowly evolving ocean boundary conditions contributed substantially to the magnitude of this heat wave. They also provide evidence that such an intense event could be produced through natural variability alone. Analysis of observations indicate that this heat wave was mainly due to internal atmospheric dynamical processes that produced and maintained a strong and long‐lived blocking event, and that similar atmospheric patterns have occurred with prior heat waves in this region. We conclude that the intense 2010 Russian heat wave was mainly due to natural internal atmospheric variability. Slowly varying boundary conditions that could have provided predictability and the potential for early warning did not appear to play an appreciable role in this event.
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•The rude product of spherical CNCs can be purified with flocculation and acid washing.•Impurities in spherical CNCs are quantitatively detected.•The purity of as-prepared sample ...reached up to approximate 99.99%.•The pure CNCs has higher thermal stability and smaller particle size.
The spherical cellulose nanocrystals (CNCs) with high purity were prepared, the processes included composite enzymolysis of pulp fibers and the purification of product. The impurities in the crude product CNCs were analyzed with FTIR, coomassie brilliant blue-G250 and ionic chromatography. The pure CNCs were characterized with SEM, XRD, DLS and TGA. The results indicated that the crude CNCs was flocculated and washed twice with a dilute acid solution (pH = 2) to get pure spherical CNCs, the purity was approximate 99.99%. The obtained pure spherical CNCs had a narrow particle size distribution with diameter 15–40 nm. FTIR and XRD analyses proved that the crystal phase of the spherical CNCs did not change, but the crystallinity decreased slightly compared with pulp fibers. The thermal degradation showed that the spherical CNCs had better thermal stability than one from other methods, and the temperature of maximum weight loss rate (Tmax) was 329.2 °C.
In recent years, studies have shown that the secretome of bone marrow mesenchymal stromal cells (BMSCs) contains many growth factors, cytokines, and antioxidants, which may provide novel approaches ...to treat ischemic diseases. Furthermore, the secretome may be modulated by hypoxic preconditioning. We hypothesized that conditioned medium (CM) derived from BMSCs plays a crucial role in reducing tissue damage and improving neurological recovery after ischemic stroke and that hypoxic preconditioning of BMSCs robustly improves these activities. Rats were subjected to ischemic stroke by middle cerebral artery occlusion and then intravenously administered hypoxic CM, normoxic CM, or Dulbecco modified Eagle medium (DMEM, control). Cytokine antibody arrays and label‐free quantitative proteomics analysis were used to compare the differences between hypoxic CM and normoxic CM. Injection of normoxic CM significantly reduced the infarct area and improved neurological recovery after stroke compared with administering DMEM. These outcomes may be associated with the attenuation of apoptosis and promotion of angiogenesis. Hypoxic preconditioning significantly enhanced these therapeutic effects. Fourteen proteins were significantly increased in hypoxic CM compared with normoxic CM as measured by cytokine arrays. The label‐free quantitative proteomics analysis revealed 163 proteins that were differentially expressed between the two groups, including 107 upregulated proteins and 56 downregulated proteins. Collectively, our results demonstrate that hypoxic CM protected brain tissue from ischemic injury and promoted functional recovery after stroke in rats and that hypoxic CM may be the basis of a potential therapy for stroke patients.
Conditioned medium constitutes a therapeutic effect on stroke. Paracrine actions of bone marrow mesenchymal stromal cell are enhanced by hypoxic preconditioning. Apoptosis and neovascularization are involved in this beneficial effect.
Background
MR imaging has been applied to determine therapeutic response to glucocorticoid (GC) before treatment in thyroid‐associated ophthalmopathy (TAO), while the performance was still poor.
...Purpose
To investigate the value of T2‐weighted imaging (T2WI)‐derived radiomics for pretreatment determination of therapeutic response to GC in TAO patients, and compare its diagnostic performance with that of semiquantitative parameters.
Study Type
Retrospective.
Population
A total of 110 patients (49 ± 12 years; male/female, n = 48/62; responsive/unresponsive, n = 62/48), divided into training (n = 78) and validation (n = 32) cohorts.
Field Strength/Sequence
3.0 T, T2‐weighted fast spin echo.
Assessment
W.C. and H.H. (6 and 10 years of experience, respectively) performed the measurements. Maximum, mean, and minimum signal intensity ratios (SIRs) of extraocular muscle (EOM) bellies were collected to construct a semiquantitative imaging model. Radiomics features from volumes of interest covering EOM bellies were extracted and three machine learning‐based (logistic regression LR; decision tree DT; support vector machine SVM) models were built.
Statistical Tests
The diagnostic performances of models were evaluated using receiver operating characteristic curve analyses, and compared using DeLong test. Two‐sided P < 0.05 was considered statistically significant.
Results
The responsive group showed higher minimum signal intensity ratio (SIRmin) of EOMs than the unresponsive group (training: 1.46 ± 0.34 vs. 1.18 ± 0.39; validation: 1.44 ± 0.33 vs. 1.19 ± 0.20). In both cohorts, LR‐based radiomics model demonstrated good diagnostic performance (area under the curve AUC = 0.968, 0.916), followed by DT‐based (AUC = 0.933, 0.857) and SVM‐based models (AUC = 0.919, 0.855). All three radiomics models outperformed semiquantitative imaging model (SIRmin: AUC = 0.805) in training cohort. In validation cohort, only LR‐based radiomics model outperformed that of SIRmin (AUC = 0.745). The nomogram integrating LR‐based radiomics signature and disease duration further elevated the diagnostic performance in validation cohort (AUC: 0.952 vs. 0.916, P = 0.063).
Data Conclusion
T2WI‐derived radiomics of EOMs, together with disease duration, provides a promising noninvasive approach for determining therapeutic response before GC administration in TAO patients.
Level of Evidence
3
Technical Efficacy
Stage 4
Gadolinium (Gd)-based contrast agents (GBCAs) have been widely used for acute ischemic stroke (AIS) patients. GBCAs or AIS alone may cause the adverse effects on kidney tissue, respectively. However, ...whether GBCAs and AIS would generate a synergistic negative effect remains undefined.
To evaluate synergistic negative effects of AIS and GBCAs on renal tissues in a mouse model of AIS, and to compare the differences of these negative effects between linear and macrocyclic GBCAs.
Animal study.
Seventy-two healthy mice underwent transient middle cerebral artery occlusion (tMCAO) and sham operation to establish AIS and sham model (N = 36/model). 5.0 mmol/kg GBCAs (gadopentetate or gadobutrol) or 250 μL saline were performed at 4.5 hours and 1 day after model establishing (N = 12/group).
Inductively coupled plasma mass spectrometry (ICP-MS) was performed to detect Gd concentrations. Serum biochemical analyzer was performed to measure the serum creatinine (Scr), uric acid (UA), and blood urea nitrogen (BUN). Pathological staining was performed to observe tubular injury, cell apoptosis, mesangial hyperplasia, and interstitial fibrosis.
Two-way analysis of variances with post hoc Sidak's tests and independent-samples t-tests were performed. A P-value <0.05 was considered statistically significant.
AIS groups showed higher Gd concentration than sham group on day 1 p.i. regardless of gadopentetate or gadobutrol used. Increased total Gd concentration was also found in AIS + gadopentetate group compared with the sham group on day 28 p.i. Significantly higher rates for renal dysfunction, higher tubular injury scores, and higher numbers of apoptotic cells on days 1 or 28 p.i. were found for AIS mice injected with GBCA. AIS + gadopentetate group displayed more severe renal damage than the AIS + gadobutrol group.
AIS and GBCAs may cause increased total Gd accumulation and nephrotoxicity in a mouse, especially linear GBCAs were used.
1 TECHNICAL EFFICACY: Stage 4.
Besides the well‐documented ophthalmic manifestations, thyroid‐associated ophthalmopathy (TAO) is believed to be related to emotional and psychological abnormalities. Given the previous neuroimaging ...evidence, we hypothesized that TAO patients would have altered neurovascular coupling associated with clinical‐psychiatric disturbances. This study was to investigate neurovascular coupling changes in TAO by combining resting‐state functional magnetic resonance imaging (rs‐fMRI) and arterial spin labeling (ASL) techniques. Amplitude of low‐frequency fluctuation (ALFF) was calculated from rs‐fMRI, and cerebral blood flow (CBF) was computed from ASL in 37 TAO patients and 21 healthy controls (HCs). Global neurovascular coupling was assessed by across‐voxel CBF‐ALFF correlation, and regional neurovascular coupling was evaluated by CBF/ALFF ratio. Auxiliary analyses were performed using fractional ALFF (fALFF) and regional homogeneity (ReHo) as rs‐fMRI measures. Compared with HCs, TAO patients showed significantly reduced global CBF‐ALFF coupling. Moreover, TAO patients exhibited decreased CBF/ALFF ratio in the left lingual gyrus (LG)/fusiform gyrus (FFG), and increased CBF/ALFF ratio in the bilateral precuneus (PCu). In TAOs, CBF/ALFF ratio in the left LG/FFG was positively correlated with visual acuity, while CBF/ALFF ratio in the bilateral PCu was negatively correlated with Montreal Cognitive Assessment score. The auxiliary analyses showed trends of reduced global neurovascular coupling (i.e., CBF‐fALFF correlation and CBF‐ReHo correlation), as well as significant altered regional neurovascular coupling (i.e., CBF/fALFF ratio and CBF/ReHo ratio) in several brain regions. These findings indicated that TAO patients had altered neurovascular coupling in the visual and higher‐order cognitive cortices. The neurovascular decoupling might be a possible neuropathological mechanism of TAO.
Although previous neuroimaging evidence has confirmed the brain functional disturbances in thyroid-associated ophthalmopathy (TAO), the dynamic characteristics of brain activity and functional ...connectivity (FC) in TAO were rarely concerned. The present study aims to investigate the alterations of temporal variability of brain activity and FC in TAO using resting-state functional magnetic resonance imaging (rs-fMRI). Forty-seven TAO patients and 30 age-, gender-, education-, and handedness-matched healthy controls (HCs) were enrolled and underwent rs-fMRI scanning. The dynamic amplitude of low-frequency fluctuation (dALFF) was first calculated using a sliding window approach to characterize the temporal variability of brain activity. Based on the dALFF results, seed-based dynamic functional connectivity (dFC) analysis was performed to identify the temporal variability of efficient communication between brain regions in TAO. Additionally, correlations between dALFF and dFC and the clinical indicators were analyzed. Compared with HCs, TAO patients displayed decreased dALFF in the left superior occipital gyrus (SOG) and cuneus (CUN), while showing increased dALFF in the left triangular part of inferior frontal gyrus (IFGtriang), insula (INS), orbital part of inferior frontal gyrus (ORBinf), superior temporal gyrus (STG) and temporal pole of superior temporal gyrus (TPOsup). Furthermore, TAO patients exhibited decreased dFC between the left STG and the right middle occipital gyrus (MOG), as well as decreased dFC between the left TPOsup and the right calcarine fissure and surrounding cortex (CAL) and MOG. Correlation analyses showed that the altered dALFF in the left SOG/CUN was positively related to visual acuity (r = .409, p = .004), as well as the score of QoL for visual functioning (r = .375, p = .009). TAO patients developed abnormal temporal variability of brain activity in areas related to vision, emotion, and cognition, as well as reduced temporal variability of FC associated with vision deficits. These findings provided additional insights into the neurobiological mechanisms of TAO.
Background
World Health Organization classification and Masaoka‐Koga stage are widely used for thymic epithelial tumors (TETs). Reduced field‐of‐view (rFOV) diffusion‐weighed imaging (DWI) proved to ...improve the image quality. Dynamic contrast‐enhanced (DCE) MRI was commonly used in evaluating tumors.
Purpose
To investigate the value of multiparametric MRI in evaluating TETs.
Study Type
Retrospective.
Subjects
Eighty‐seven participants including 38 low risk (52.08 ± 14.19 years), 30 high risk (52.40 ± 11.35 years), and 19 thymic carcinoma patients (59.76 ± 10.78 years).
Field strength/Sequence
A 3 T, turbo spin echo imaging, echo planar imaging, volumetric interpolated breath‐hold examination with radial acquisition trajectory.
Assessment
DCE‐MRI and apparent diffusion coefficient (ADC) variables were compared. Diagnostic performances of single significant factor and combined model were compared.
Statistical Tests
Parameters were compared using one‐way ANOVA or independent‐samples t test. Logistic regression was employed to investigate the combined model. Receiver operating curves (ROC) and DeLong's test were used to compare the diagnostic efficiency.
Results
ADC, Ktrans, and kep values were significantly different among low‐risk, high‐risk and carcinoma group (ADC, 1.279 ± 0.345 × 10−3 mm2/sec, 0.978 ± 0.260 × 10−3 mm2/sec, 0.661 ± 0.134 × 10−3 mm2/sec; Ktrans 0.167 ± 0.071 min−1, 0.254 ± 0.136 min−1, 0.393 ± 0.110 min−1; kep 0.345 ± 0.113 min−1, 0.560 ± 0.269 min−1, 0.872 ± 0.149 min−1). They were significantly different for early stage and advanced stage (ADC, 1.270 ± 0.356 × 10−3 mm2/sec vs. 0.845 ± 0.251 × 10−3 mm2/sec; Ktrans 0.179 ± 0.092 min−1 vs. 0.304 ± 0.142 min−1; kep 0.370 ± 0.181 min−1 vs. 0.674 ± 0.362 min−1). The combination of them had highest diagnostic efficiency for WHO classification (AUC, 0.925; sensitivity, 83.7%; specificity, 89.5%), clinical stage (AUC, 0.879; sensitivity, 80.9%; specificity, 82.5%).
Data Conclusion
Multiparametric MRI model may be useful for discriminating WHO classification and clinical stage of TETs.
Evidence Level
4
Technical Efficiency
Stage 2
Purpose
To investigate the effects of gadolinium (Gd) retention of macrocyclic (gadobutrol) or linear (gadopentetate) Gd‐based contrast agents (GBCAs) on neuron loss, neurological deficits, and ...sensory behavior in mice with or without stroke.
Methods
Ninety C57BL/6 mice underwent sham (n = 36) or transient middle cerebral artery occlusion (tMCAO) (n = 54) surgery and then received intraperitoneal injections of 5.0 mmol/kg gadobutrol, 5.0 mmol/kg gadopentetate or saline (10 ml/kg/administration) per day for 3 consecutive days. The Gd concentration in the ischemic cerebrum was quantified by inductively coupled plasma mass spectrometry on Day 1 and Day 28 after the last injection (post‐injection, p. i.). Neuron loss, glia activation and neurological deficits were assessed on Day 1 and 28 p. i. Sensory behavior was also assessed on Day 28 p. i.
Results
Gd concentrations were higher in the brains of tMCAO mice than in those of sham mice on Days 1 p. i. of both GBCAs (gadobutrol, p < 0.05; gadopentetate, p < 0.001) and 28 p. i of gadopentetate. (p < 0.001). Sham or tMCAO mice injected with GBCAs showed no significant difference in neuron loss, glia activation, neurological deficits, brain atrophy, or hippocampus‐dependent memory (all p > 0.05). Both gadobutrol and gadopentetate induced mechanical and heat hyperalgesia in sham mice (all p < 0.05). However, mechanical hyperalgesia but rather heat hyperalgesia was found in tMCAO mice with the highest force tested (1.0 g) and statistically significant in both paws (right and left) with gadopentetate only (p < 0.05).
Conclusions
Neither gadobutrol nor gadopentetate worsened neuron loss, glia activation, brain atrophy, neurological deficits, or hippocampus‐dependent memory after tMCAO. However, GBCA administration induced mechanical hyperalgesia in sham and tMCAO mice although in the same level, which may be an important consideration for patients with central post‐stroke pain and those who are sensitive to pain and about to receive multiple GBCA administrations.
