Pine wilt disease detection algorithm based on improved YOLOv5.

Pine wilt disease (PWD) poses a significant threat to forests due to its high infectivity and lethality. The absence of an effective treatment underscores the importance of timely detection and isolation of infected trees for effective prevention and control. While deep learning techniques combined unmanned aerial vehicle (UAV) remote sensing images offer promise for accurate identification of diseased pine trees in their natural environments, they often demand extensive prior professional knowledge and struggle with efficiency. This paper proposes a detection model YOLOv5L-s-SimAM-ASFF, which achieves remarkable precision, maintains a lightweight structure, and facilitates real-time detection of diseased pine trees in UAV RGB images under natural conditions. This is achieved through the integration of the ShuffleNetV2 network, a simple parameter-free attention module known as SimAM, and adaptively spatial feature fusion (ASFF). The model boasts a mean average precision (mAP) of 95.64% and a recall rate of 91.28% in detecting pine wilt diseased trees, while operating at an impressive 95.70 frames per second (FPS). Furthermore, it significantly reduces model size and parameter count compared to the original YOLOv5-Lite. These findings indicate that the proposed model YOLOv5L-s-SimAM-ASFF is most suitable for real-time, high-accuracy, and lightweight detection of PWD-infected trees. This capability is crucial for precise localization and quantification of infected trees, thereby providing valuable guidance for effective management and eradication efforts.

Is intravoxel incoherent motion magnetic resonance imaging useful for predicting hepatocellular cancer recurrence and invasion of the peritumoral zone after transarterial chemoembolization?

PURPOSE: We evaluated the potential role of intravoxel incoherent motion (IVIM) in predicting the therapeutic response and peritumoral invasion in patients with hepatocellular carcinoma (HCC) treated with transarterial chemoembolization (TACE). MATERIALS AND METHODS: We enrolled 47 patients previously treated with TACE between January 2018 and December 2021. We evaluated the IVIM-derived metrics [apparent diffusion coefficient (ADC), D, D*, f] in the TACE-treated, peritumoral, and parenchymal areas of the liver. RESULTS: The ADCtace and Dtace values (1.13 ± 0.22 × 10-3 m2/s vs 0.95 ± 0.13 × 10-3 mm2/s, 1.28 ± 0.27 × 10-3 mm2/s vs 1.07 ± 0.3 × 10-3 mm2/s, P < 0.05) were higher in the non-progressing groups than in the progressing groups in the TACE-treated areas. Dpt represented the D values in the peritumoral area, which can distinguish between the progressive and non-progressive groups with an AUC of 0.73. The Dstd values, which represent the D values in the peritumoral area normalized by the D values in the liver parenchyma in the non-progressing groups (1.10 ± 0.14 × 10-3 mm2/s), were higher than those of the progressing groups (0.93 ± 0.17 × 10-3 mm2/s). CONCLUSION: The ADCtace, Dtace, Dpt, and Dstd values reflect the changes in the microstructure of the progressive and non-progressive groups after TACE treatment, showing robust diagnostic performances in predicting the therapeutic response and peritumoral invasion.

Rare-Earth Metal Phosphinidene Complexes: A Trip from Bridging One to Terminal One.

ConspectusAs phosphorus analogues of alkylidene (or carbene) and imido (or nitrene) complexes, phosphinidene complexes have received great attention not only for their fundamental scientific merits but also for their ability to build new phosphorus-containing molecules. A large number of phosphinidene complexes in bridging, mononuclear, or terminal coordination modes have been synthesized, and their reactivity has been extensively explored. However, the synthesis of rare-earth metal (scandium, yttrium, and lanthanide metal) phosphinidene complexes lagged behind the transition metal and actinide congeners for decades. Rare-earth metal ions are among the hardest Lewis acids, whereas phosphinidene ligands are soft Lewis bases; rare-earth metal-phosphinidene coordination is thus mismatched based on the Pearson's HSAB principle. The bridging rare-earth metal phosphinidene complexes were not reported until 2008, and the synthesis of the mononuclear and terminal species is even more challenging, which has only recently been achieved.Our group reported a bis(µ2-phosphinidene)dineodymium complex in 2008. In the following >10 years, we have been pursuing the terminal rare-earth metal phosphinidene complexes. Due to the high instability of rare-earth metal-phosphorus multiple bonds, the synthesis and stabilization of these complexes are extremely difficult. Finally, by using suitable phosphinidene ligands and supporting ligands, we obtained the first mononuclear rare-earth metal phosphinidene complex in 2018 and the first terminal rare-earth metal phosphinidene complex in 2020. In these more than ten years of research, we have also found some interesting reactivity of the rare-earth metal phosphinidene complexes. The rare-earth metal bridging phosphinidene complexes can act as two-electron reductants based on the oxidative coupling of two phosphinidene ligands into a diphosphene ligand. The mononuclear rare-earth metal phosphinidene complexes catalyze the hydrogenation of terminal alkenes under mild conditions, and the joint experimental/DFT studies indicate that the hydrogenation reaction proceeds in a 1,2-addition/elimination mechanism rather than the common σ-bond metathesis mechanism. These reactivities are new and important for the rare-earth metal complexes. In addition, the ligand design in our study may contribute to the synthesis of rare-earth metal-arsenic multiple bonding complexes and alkaline-earth metal-phosphorus multiple bonding complexes, which have not yet been realized. Herein, we present an account of our investigations into rare-earth metal phosphinidene complexes, a trip from bridging one to terminal one. To give the readers an overall image of the development of the rare-earth metal phosphinidene complexes, some findings from other researchers are also included.

T1 relaxation time analysis in predicting hepatic dysfunction and prognosis in patients with HCC undergoing transarterial chemoembolization.

OBJECTIVE: To evaluate the value of T1 mapping in predicting hepatic dysfunction and prognosis in patients with hepatocellular carcinoma (HCC) undergoing transarterial chemoembolization (TACE). MATERIAL AND METHODS: 100 consecutive patients with treatment-naive HCC treated with TACE were prospectively analyzed. Clinical, laboratory, and MRI parameters (liver and tumor T1 relaxation times (T1L, T1T)) before and/or following TACE were measured and calculated. Clinical parameters included the Child-Turcotte-Pugh (CTP) classification, Barcelona Clinic Liver Cancer Classification (BCLC) criteria, and albumin-bilirubin (ALBI) score. Laboratory parameters were the gold standard for hepatic dysfunction. T1L and T1T were combined by stepwise multivariate logistic regression to yield a T1-related probability index (T1com) for further analysis. Study endpoints included hepatic dysfunction and progression-free survival (PFS) rate. RESULTS: 38 patients (38%) were diagnosed with hepatic dysfunction following TACE. There was no significant difference in clinical parameters between the groups with and without hepatic dysfunction. Logistic regression analysis showed that T1L and T1T were independent risk factors for assessing hepatic dysfunction. T1com showed a better AUC than T1L and T1T (0.81 vs. 0.76 and 0.69, P = 0.007 and 0.006). Patients with low T1com (≤0.42) showed a better median PFS than patients with high T1com (>0.42) (167.0 vs. 215.9 days, P = 0.010). In comparison, CTP, BCLC, and ALBI scores were not statistically significant in predicting PFS in HCC patients treated with TACE (P > 0.05). CONCLUSION: Compared with widely used clinical parameters, T1 was more capable of predicting hepatic dysfunction after TACE. Stratification of patients with HCC undergoing TACE according to T1 may help clinicians to develop treatment strategies in preventing the occurrence of hepatic dysfunction and improving individual prognoses.

Lateralization of temporal lobe epileptic foci with automated chemical exchange saturation transfer measurements at 3 Tesla.

BACKGROUND: Magnetic Resonance Imaging (MRI) is an indispensable tool for the diagnosis of temporal lobe epilepsy (TLE). However, about 30% of TLE patients show no lesion on structural MRI (sMRI-negative), posing a significant challenge for presurgical evaluation. This study aimed to investigate whether chemical exchange saturation transfer (CEST) MRI at 3 Tesla can lateralize the epileptic focus of TLE and study the metabolic contributors to the CEST signal measured. METHODS: Forty TLE subjects (16 males and 24 females) were included in this study. An automated data analysis pipeline was established, including segmentation of the hippocampus and amygdala (HA), calculation of four CEST metrics and quantitative relaxation times (T1 and T2), and construction of prediction models by logistic regression. Furthermore, a modified two-stage Bloch-McConnell fitting method was developed to investigate the molecular imaging mechanism of 3 T CEST in identifying epileptic foci of TLE. FINDINGS: The mean CEST ratio (CESTR) metric within 2.25-3.25 ppm in the HA was the most powerful index in predicting seizure laterality, with an area under the receiver-operating characteristic curve (AUC) of 0.84. And, the combination of T2 and CESTR further increased the AUC to 0.92. Amine and guanidinium moieties were the two leading contributors to the CEST contrast between the epileptogenic HA and the normal HA. INTERPRETATION: CEST at 3 Tesla is a powerful modality that can predict seizure laterality with high accuracy. This study can potentially facilitate the clinical translation of CEST MRI in identifying the epileptic foci of TLE or other localization-related epilepsies. FUNDING: National Natural Science Foundation of China, Science Technology Department of Zhejiang Province, and Zhejiang University.

Identification and functional characterization of protein kinase R (PKR) in amphibian Xenopus tropicalis.

As one of interferon-induced serine/threonine kinases, the protein kinase R (PKR) plays vital roles in antiviral defense, and functional features of PKR remain largely unknown in amphibians, which suffer from ranaviral diseases in the last few decades. In this study, a PKR gene named Xt-PKR was characterized in the Western clawed frog (Xenopus tropicalis). Xt-PKR gene was widely expressed in different organs/tissues, and was rapidly induced by poly(I:C) in spleen, kidney, and liver. Intriguingly, Xt-PKR could be up-rugulated by the treatment of type I and type III interferons, and the transcript level of Xt-PKR induced by type I interferon was much higher than that of type III interferon. Moreover, overexpression of Xt-PKR can suppress the protein synthesis and ranavirus replication in vitro, and the residue lysine required for the translation inhibition activity in mammalian PKR is conserved in Xt-PKR. The present study represents the first characterization on the functions of amphibian PKR, and reveals considerable functional conservation of PKR in early tetrapods.

A comparative study of quantitative metrics in chemical exchange saturation transfer imaging for grading gliomas in adults.

PURPOSE: To evaluate the performance of different chemical exchange saturation transfer (CEST) metrics for grading gliomas with semiautomatically defined regions of interest (ROIs). METHODS: Thirty-eight adult subjects were included, including 23 high-grade gliomas and 15 low-grade gliomas confirmed by histopathology. The B0-corrected CEST z-spectra were first calculated with magnetization transfer ratio asymmetry (MTRasym) analysis at frequency offsets of 3.5, 3, 2.5, 2, 1.5, and 1 ppm to obtain the fit-free metrics and subsequently fitted with three Lorentzian functions denoting direct water saturation (DS), amide proton transfer (APT), and combined semisolid magnetization transfer and nuclear Overhauser enhancement (MT & NOE) effects to derive the fit-based metrics. Wilcoxon rank-sum test was performed to determine if a statistically significant difference was present in the CEST metrics between low- and high-grade gliomas. Receiver operating characteristic (ROC) curves were used to evaluate the differentiation of CEST metrics between low- and high-grade gliomas. Pearson correlation coefficients were employed to evaluate the correlations of CEST metrics. RESULTS: For the fit-free metrics, the highest areas under the curve (AUCs) of 0.85, 0.88, and 0.88, corresponding to MTRasym, MTRnormref (normalization by the reference scan), and MTRRex (subtraction of inverse z-spectra), respectively, were obtained at 3 ppm across various frequency offsets. In addition, the AUCs generated from the fit-based metrics (0.88-0.90) were higher than those generated from the fit-free metrics at 3 ppm. CONCLUSION: The results of this preliminary study indicate that fit-free CEST metrics at 3 ppm are superior to the other frequency offsets for grading human brain gliomas. The fit-based metrics manifested improved differentiation between low- and high-grade gliomas compared to the fit-free CEST metrics.

Development of visual cortex in human neonates is selectively modified by postnatal experience.

Experience-dependent cortical plasticity is a pivotal process of human brain development and essential for the formation of most cognitive functions. Although studies found that early visual experience could influence the endogenous development of visual cortex in animals, little is known about such impact on human infants. Using the multimodal MRI data from the developing human connectome project, we characterized the early structural and functional maps in the ventral visual cortex and their development during neonatal period. Particularly, we found that postnatal time selectively modulated the cortical thickness in the ventral visual cortex and the functional circuit between bilateral primary visual cortices. But the cortical myelination and functional connections of the high-order visual cortex developed without significant influence of postnatal time in such an early period. The structure-function analysis further revealed that the postnatal time had a direct influence on the development of homotopic connection in area V1, while gestational time had an indirect effect on it through cortical myelination. These findings were further validated in preterm-born infants who had longer postnatal time but shorter gestational time at birth. In short, these data suggested in human newborns that early postnatal time shaped the structural and functional development of the visual cortex in selective and organized patterns.

Radiomics combined with clinical features in distinguishing non-calcifying tuberculosis granuloma and lung adenocarcinoma in small pulmonary nodules.

Aim: To evaluate the performance of radiomics models with the combination of clinical features in distinguishing non-calcified tuberculosis granuloma (TBG) and lung adenocarcinoma (LAC) in small pulmonary nodules. Methodology: We conducted a retrospective analysis of 280 patients with pulmonary nodules confirmed by surgical biopsy from January 2017 to December 2020. Samples were divided into LAC group (n = 143) and TBG group (n = 137). We assigned them to a training dataset (n = 196) and a testing dataset (n = 84). Clinical features including gender, age, smoking, CT appearance (size, location, spiculated sign, lobulated shape, vessel convergence, and pleural indentation) were extracted and included in the radiomics models. 3D slicer and FAE software were used to delineate the Region of Interest (ROI) and extract clinical features. The performance of the model was evaluated by the Area Under the Receiver Operating Characteristic (ROC) Curve (AUC). Results: Based on the model selection, clinical features gender, and age in the LAC group and TBG group showed a significant difference in both datasets (P < 0.05). CT appearance lobulated shape was also significantly different in the LAC group and TBG group (Training dataset, P = 0.034; Testing dataset, P = 0.030). AUC were 0.8344 (95% CI [0.7712-0.8872]) and 0.751 (95% CI [0.6382-0.8531]) in training and testing dataset, respectively. Conclusion: With the capacity to detect differences between TBG and LAC based on their clinical features, radiomics models with a combined of clinical features may function as the potential non-invasive tool for distinguishing TBG and LAC in small pulmonary nodules.

Synthesis, Characterization, and Reactivity of a Hydrido- and Imido-Bridged Dinuclear Ytterbium(III) Complex.

The trivalent rare-earth metal hydrido and imido complexes are of versatile reactivity, and many such complexes have been synthesized. However, no example of a rare-earth metal complex bearing both hydrido- and imido-ligands has been reported. Herein, we report the first rare-earth metal complex bearing both hydrido- and imido-ligands, namely a hydrido- and imido-bridged dinuclear ytterbium(III) complex. The complex was synthesized via an unprecedented redox reaction of divalent rare-earth metal hydrido complex with azido compound. DFT calculation indicated that the N2 release from azido compound in the presence of ytterbium(II) is a kinetically facile process because of the cooperative effects of the two metal centers. The reactivity of the hydrido- and imido-bridged dinuclear ytterbium(III) complex was also explored, which showed the redox, addition and σ-bond metathesis reactivities.

Prevalence and clinical outcomes of pleural effusion in COVID-19 patients: A systematic review and meta-analysis.

Observational studies indicate that pleural effusion has an association with risk and the clinical prognosis of COVID-19 disease; however, the available literature on this area is inconsistent. The objective of this systematic review and meta-analysis is to evaluate the correlation between COVID-19 disease and pleural effusion. A rigorous literature search was conducted using multiple databases. All eligible observational studies were included from around the globe. The pooled prevalence and associated 95% confidence interval (CI) were calculated using the random effect model. Mantel-Haenszel odds ratios were produced to report overall effect size using random effect models for severity and mortality outcomes. Funnel plots, Egger regression tests, and Begg-Mazumdar's rank correlation test were used to appraise publication bias. Data from 23 studies including 6234 COVID-19 patients was obtained. The overall prevalence of pleural effusion in COVID-19 patients was 9.55% (95% CI, I2 = 92%). Our findings also indicated that the presence of pleural effusions associated with increased risk of severity of disease(OR = 5.08, 95% CI 3.14-8.22, I2 = 77.4%) and mortality due to illness(OR = 4.53, 95% CI 2.16-9.49, I2 = 66%) compared with patients without pleural effusion. Sensitivity analyses illustrated a similar effect size while decreasing the heterogeneity. No significant publication bias was evident in the meta-analysis. The presence of pleural effusion can assist as a prognostic factor to evaluate the risk of worse outcomes in COVID-19 patients hence, it is recommended that hospitalized COVID-19 patients with pleural effusion should be managed on an early basis.

The effect of beta-amyloid and tau protein aggregations on magnetic susceptibility of anterior hippocampal laminae in Alzheimer's diseases.

Previous studies have reported the changes of magnetic susceptibility induced by iron deposition in hippocampus of Alzheimer's disease (AD) brains. It is well-known that hippocampus is divided into well-defined laminar architecture, which, however, is difficult to be resolved with in-vivo MRI due to the limited imaging resolution. The present study aims to investigate layer-specific magnetic susceptibility in the hippocampus of AD patients using high-resolution ex-vivo MRI, and elucidate its relationship with beta amyloid (Aß) and tau protein histology. We performed quantitative susceptibility mapping (QSM) and T2* mapping on postmortem anterior hippocampus samples from four AD, four Primary Age-Related Tauopathy (PART), and three control brains. We manually segmented each sample into seven layers, including four layers in the cornu ammonis1 (CA1) and three layers in the dentate gyrus (DG), and then evaluated AD-related alterations of susceptibility and T2* values and their correlations with Aß and tau in each hippocampal layer. Specifically, we found (1) layer-specific variations of susceptibility and T2* measurements in all samples; (2) the heterogeneity of susceptibility were higher in all layers of AD patients compared with the age- and gender-matched PART cases while the heterogeneity of T2* values were lower in four layers of CA1; and (3) voxel-wise MRI-histological correlation revealed both susceptibility and T2* values in the stratum molecular (SM) and stratum lacunosum (SL) layers were correlated with the Aß content in AD, while the T2* values in the stratum radiatum (SR) layer were correlated with the tau content in the PART but not AD. These findings suggest a selective effect of the Aß- and tau-pathology on the susceptibility and T2* values in the different layers of anterior hippocampus. Particularly, the alterations of magnetic susceptibility in the SM and SL layers may be associated with Aß aggregation, while those in the SR layermay reflect the age-related tau protein aggregation.

Crimean-Congo haemorrhagic fever-induced liver injury: A systematic review and meta-analysis.

BACKGROUND: Crimean-Congo haemorrhagic fever (CCHF) is a fatal acute tick-borne viral infection and substantial emerging global public health threat. This illness has a high case fatality rate of up to 40%. The liver is one of the important target organs of the CCHF virus. OBJECTIVE: The aim of this meta-analysis to evaluate the correlation between CCHF and liver injury and draw more generalised inferences about the abnormal serum markers of liver injury such as alanine aminotransferase (ALT), aspartate aminotransferase (AST) in CCHF patients. METHODS: A literature search was accomplished for published eligible articles with MEDLINE/PubMed and Embase databases. All eligible observational studies and case series were included from around the world. The inclusion criteria were articles describing liver injury biomarkers amongst patients diagnosed with CCHF. RESULTS: Data from 18 studies, consisting of 1238 patients with CCHF were included in this meta-analysis. Overall pooled incidence of at least one raised liver injury biomarker was 77.95% (95% CI, I2  =  88.50%, P < .0001). Similarly, pooled incidence of elevated AST and ALT was 85.92% (95% CI, I2  = 85.27%, P < .0001) and 64.30% (95% CI, I2  =  88.32%, P < .0001), respectively. Both Egger and Begg-Mazumdar's tests detected no apparent publication bias in all three meta-analyses (P > .05). CONCLUSION: Our study shows that CCHF has a very detrimental effect on liver function. Abnormal liver function may lead to poor prognosis and increased morbidity and mortality in CCHF patients. Hence, Physicians must recognise and continuously monitor these biomarkers, since these markers may aid in early stratification of prognosis and the prevention of severe outcomes in infection with such a high case fatality rate.

Myocarditis associated with Covid-19 disease: A systematic review of published case reports and case series.

BACKGROUND: Covid-19 is an extremely contagious illness caused by the severe acute respiratory syndrome (SARS-CoV-2) virus. The cardiac involvement in such a public health emergency disease has not been well studied and a conflicting evidence exists on this issue. OBJECTIVE: This systematic review article aimed to compile and illustrate clinical characteristics, diagnostic findings, management, and outcomes manifesting in myocarditis linked with Covid-19. METHODS: A literature search was accomplished for published eligible articles with MEDLINE/PubMed and Embase databases. All eligible case reports and case series were included from around the world without any language restrictions. For this review, inclusion criteria were laboratory-confirmed SARS-CoV-2 infection cases reporting a diagnosis of acute myocarditis. RESULTS: Data from 41 studies describing myocarditis in 42 Covid-19 patients was obtained. The median age of these patients was 43.4 years, with 71.4% of them being men. Fever was the most prevalent presenting symptoms seen in 57% of patients. Hypertension was the most pervasive comorbidity accompanying these patients. Cardiac biomarkers troponin and brain natriuretic peptide (BNP) were raised in almost 90% and 87% of patients, respectively. Electrocardiogram findings were nonspecific and included ST-segment and T-wave changes. Echocardiogram commonly showed left ventricular systolic dysfunction with increased heart size. Cardiac magnetic resonance imaging (CMRI) exhibited myocardial edema and injury. The most prevalent histopathological feature appreciated was diffuse lymphocytic inflammatory infiltrates. Antivirals and corticosteroids were the most frequently used medications. About 38% of patients also needed vasopressor assistance. Out of 42 patients, 67% recovered, and eight died. CONCLUSION: Because of the risk of a sudden worsening of patients conditions and myocarditis association with considerable mortality and morbidity, a knowledge of this cardiac complication of Covid-19 disease is crucial for healthcare professionals.

Chemical exchange saturation transfer imaging for epilepsy secondary to tuberous sclerosis complex at 3 T: Optimization and analysis.

The homeostasis of various metabolites is impaired in epilepsy secondary to the tuberous sclerosis complex (TSC). Chemical exchange saturation transfer (CEST) imaging is an emerging molecular MRI technique that can detect various metabolites and proteins in vivo. However, the role of CEST imaging for TSC-associated epilepsy has not been assessed. Here, we aim to investigate the feasibility of applying CEST imaging to TSC-associated epilepsy, optimize the CEST acquisition parameters, and provide an analysis method for exploring the dominant molecular contributors to the CEST signal measured. Nine TSC epilepsy patients were scanned on a 3-T MRI system. The CEST saturation frequencies were swept from -6 to 6 ppm with 12 different combinations of saturation power (4, 3, 2 and 1 µT) and duration (1000, 700 and 400 ms). Furthermore, a two-stage simulation method based on the seven-pool Bloch-McConnell model was proposed to assess the contribution of each exchangeable pool to the CEST signal in normal-appearing white matter and cortical tubers, which avoided the complexity and uncertainty of full Bloch-McConnell fitting. The results showed that under the optimal saturation duration of 1000 ms, the greatest contrast between tubers and normal tissues occurred around 3, 2.5, 1.75 and 3.5 ppm for B1 of 4, 3, 2 and 1 µT, respectively. At the optimal frequency offsets, the CEST values of tubers were significantly higher than those in the normal brain tissues (P < 0.01). Furthermore, the two-stage analysis suggested that the amine pool played a dominant role in yielding the contrast between cortical tubers and normal tissues. These results indicate that CEST MRI may serve as a potentially useful tool for identifying tubers in TSC, and the two-stage analysis method may provide a route for investigating the molecular contributions to the CEST contrast in biological tissues.

Divalent Ytterbium Hydrido Complex Supported by a ß-Diketiminato-Based Tetradentate Ligand: Synthesis, Structure, and Reactivity.

While the chemistry of trivalent rare-earth metal hydrido complexes has been well developed in the past 40 years, that of the divalent rare-earth metal hydrido complexes remains in its infancy because of the synthetic challenge of such complexes. In this paper, we report the synthesis and structural characterization of a divalent ytterbium hydrido complex supported by a bulky ß-diketiminato-based tetradentate ligand. This hydrido complex is a dimer containing two µ-hydrogen ligands, and it easily undergoes a hydrido shift reaction to form a new divalent ytterbium hydrido complex that contains only one hydrido bridge. Furthermore, this hydrido complex reacts with pyridine and pyridine derivatives, showing versatile reactivity [Yb-H addition to pyridine, hydrido shift to ancillary ligand, and ytterbium(II)-center-induced redox reaction with bipyridine]. This hydrido complex reacts with Ph3P═O, resulting in a P-CPh cleavage of Ph3P═O and an elimination of C6H6; on the other hand, the reaction with Ph3P═S is a hydrido coupling-based redox reaction. The reactions of this hydrido complex with 1 and 2 equiv of PhSSPh clearly indicate that the hydrido coupling-based redox reaction is prior to the ytterbium(II) oxidation-based redox reaction.

Ultra-High-Resolution in vitro MRI Study of Age-Related Brain Subcortical Susceptibility Alteration in Rhesus Monkeys at 9.4 T.

Iron concentration in the brain has been suggested as a biomarker of pathologic neurodegeneration. However, the iron concentration changes in healthy aging as well. This study aimed to quantify the age-related changes in iron concentration in the gray matter of healthy rhesus monkeys using quantitative susceptibility mapping (QSM). Three-dimensional gradient-echo images of 16 female rhesus monkey brains aged between 2 and 26 years were acquired in vitro. The susceptibilities in the brain regions of the caudate nucleus (Cd), putamen (Pt), globus pallidus (Gp), and substantia nigra (Sn) were analyzed. The susceptibility varied across different brain regions, with higher levels in the Gp and Sn. Susceptibilities in all analyzed brain regions were linearly correlated with age, yet the plateau period as observed in human brains was absent. This is the first in vitro report of the age-related variability of susceptibility in the deep gray matter of rhesus monkey brains at 9.4 T, with an isotropic resolution of 150 µm. Awareness of age-related changes in susceptibility is vital for the establishment of a baseline to facilitate the differentiation of pathologic neurodegeneration from healthy aging in non-human primate studies.

Dynamic changes in vascular size and density in transgenic mice with Alzheimer's disease.

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases. Here, we used vessel size imaging to investigate the specific microvascular changes and most susceptible brain regions during AD progression in an amyloid precursor protein 23 (APP23) transgenic AD mouse model. Using 9.4 Tesla magnetic resonance imaging (MRI), the values of microvascular density (Density), mean vessel diameter (mVD), and vessel size index (VSI) were compared between APP23 and wild-type (WT) mice at 3, 6, 9, 14, and 20 months of age. Our results demonstrate that in 20-month old APP23 and WT mice, the Density values were significantly decreased, while the vascular dilatation and diameter had increased. However, a transient increase in the cortex Density at 14-months was observed in APP23 mice. Additionally, our results suggest that the hippocampus is the susceptible brain region affected by the abnormal microvascular angiogenesis during the early stages of AD. Together, our findings indicate that vessel size imaging using MRI can provide novel biomarkers for the early detection of AD, and for monitoring the effects of vascular-targeted therapeutics in AD.

OsLFR is essential for early endosperm and embryo development by interacting with SWI/SNF complex members in Oryza sativa.

Rice (Oryza sativa L.) endosperm provides the developing embryo with nutrients and provides human beings with a staple food. The embryo eventually develops into a new sporophyte generation. Despite their important roles, the molecular mechanisms underlying early-stage endosperm and embryo development remain elusive. Here, we established the fundamental functions of rice OsLFR, an ortholog of the Arabidopsis SWI/SNF chromatin-remodeling complex (CRC) component LFR. OsLFR was expressed primarily in the rice spikelets and seeds, and the OsLFR protein was localized to the nucleus. We conducted genetic, cellular and molecular analyses of loss-of-function mutants and transgenic rescue lines. OsLFR depletion resulted in homozygous lethality in the early seed stage through endosperm and embryo defects, which could be successfully recovered by the OsLFR genomic sequence. Cytological observations revealed that the oslfr endosperm had relatively fewer free nuclei, had abnormal and arrested cellularization, and demonstrated premature programed cell death: the embryo was reduced in size and failed to differentiate. Transcriptome profiling showed that many genes, involved in DNA replication, cell cycle, cell wall assembly and cell death, were differentially expressed in a knockout mutant of OsLFR (oslfr-1), which was consistent with the observed seed defects. Protein-protein interaction analysis showed that OsLFR physically interacts with several putative rice SWI/SNF CRC components. Our findings demonstrate that OsLFR, possibly as one component of the SWI/SNF CRC, is an essential regulator of rice seed development, and provide further insights into the regulatory mechanism of early-stage rice endosperm and embryo development.