Pathway-Specific Mediation Effect Between Structure, Function, and Motor Impairment After Subcortical Stroke.

BACKGROUND AND OBJECTIVE: To investigate the pathway-specific correspondence between structural and functional changes resulting from focal subcortical stroke and their causal influence on clinical symptom. METHODS: In this retrospective, cross-sectional study, we mainly focused on patients with unilateral subcortical chronic stroke with moderate-severe motor impairment assessed by Fugl-Meyer Assessment (upper extremity) and healthy controls. All participants underwent both resting-state fMRI and diffusion tensor imaging. To parse the pathway-specific structure-function covariation, we performed association analyses between the fine-grained corticospinal tracts (CSTs) originating from 6 subareas of the sensorimotor cortex and functional connectivity (FC) of the corresponding subarea, along with the refined corpus callosum (CC) sections and interhemispheric FC. A mediation analysis with FC as the mediator was used to further assess the pathway-specific effects of structural damage on motor impairment. RESULTS: Thirty-five patients (mean age 52.7 ± 10.2 years, 27 men) and 43 healthy controls (mean age 56.2 ± 9.3 years, 21 men) were enrolled. Among the 6 CSTs, we identified 9 structurally and functionally covaried pathways, originating from the ipsilesional primary motor area (M1), dorsal premotor area (PMd), and primary somatosensory cortex (p < 0.05, corrected). FC for the bilateral M1, PMd, and ventral premotor cortex covaried with secondary degeneration of the corresponding CC sections (p < 0.05, corrected). Moreover, these covarying structures and functions were significantly correlated with the Fugl-Meyer Assessment (upper extremity) scores (p < 0.05, uncorrected). In particular, FC between the ipsilesional PMd and contralesional cerebellum (ß = -0.141, p < 0.05, CI = [-0.319 to -0.015]) and interhemispheric FC of the PMd (ß = 0.169, p < 0.05, CI = [0.015-0.391]) showed significant mediation effects in the prediction of motor impairment with structural damage of the CST and CC. DISCUSSIONS: This study reveals causal influence of structural and functional pathways on motor impairment after subcortical stroke and provides a promising way to investigate pathway-specific structure-function coupling. Clinically, our findings may offer a circuit-based evidence for the PMd as a critical neuromodulation target in more impaired patients with stroke and also suggest the cerebellum as a potential target.

Magnetic resonance temperature imaging of laser-induced thermotherapy using proton resonance frequency shift: evaluation of different sequences in phantom and porcine brain at 7 T.

PURPOSE: The present study aimed to evaluate magnetic resonance (MR) thermometry using proton resonance frequency shift (PRFS) during laser-induced thermotherapy (LITT), and to compare the results of using different sequences at a field strength of 7-Tesla to identify the optimal for use in ablation so that the surrounding healthy tissues may be protected from damaging in real time. MATERIALS AND METHODS: LITT was applied to agarose gel phantoms and ex-vivo porcine brains. We reconstructed both magnitude and phase images to perform MR thermometry based on PRFS methods. We tested four different sequences: a gradient-echo (GRE), a segmented gradient-echo echoplanar imaging (EPI-GRE), a fast-low angle shot (FLASH), and a true fast imaging with steady precession (TRUFI). Temperature was monitored and verified using a fiber-optic thermometry device. RESULTS: All sequences showed good linear correlations (R = 0.97-0.99) between the measured temperature and the calculated MR-thermometry measurements. The phantom/porcine brain experiments revealed the temperature precisions at 1.53/0.69 °C (GRE), 0.61/0.43 °C (EPI-GRE), 1.64/1.32 °C (FLASH), and 0.58/1.52 °C (TRUFI), respectively. Furthermore, we performed a Bland-Altman analysis and the temperature accuracies were found to be - 1.32/- 0.60 °C (GRE), 0.42/- 0.33 °C (EPI-GRE), - 1.28/- 0.98 °C (FLASH), and 0.14/0.46 °C (TRUFI) in the phantom/porcine brain experiments, respectively. CONCLUSIONS: Our experiments recommend that EPI-GRE sequence be the best of the all sequences for MR temperature imaging with PRFS in the LITT on 7 T magnetic resonance imaging (MRI) systems because of its relatively higher precision and accuracy.

Improved magnetic resonance myelin water imaging using multi-channel denoising convolutional neural networks (MCDnCNN).

Background: Myelin water imaging (MWI) is powerful and important for studying and diagnosing neurological and psychiatric diseases. In particular, myelin water fraction (MWF) is derived from MWI data for quantifying myelination. However, MWF estimation is typically sensitive to noise. Improving the accuracy of MWF estimation based on WMI data acquired using a magnetic resonance (MR) multiple gradient recalled echo (mGRE) imaging sequence is desired. Methods: The proposed method employs a recently introduced the multi-channel denoising convolutional neural networks (MCDnCNN). Five different MCDnCNN models, denoted as Delevel1, Delevel2, Delevel3, Delevel4 and DelevelMix corresponding to five noise levels (Level1, Level2, Level3, Level4 and LevelMix), were trained using the data of the first echo of the mGRE brain images acquired from 15 healthy human subjects. Using simulated noisy data that employed a hollow cylinder model, we first evaluated the improvement in estimating MWF based on data denoised by the five different MCDnCNNs, by comparing the MWF maps calculated from the denoised data with ground truth. Next, we again evaluated the improvement using real-world in vivo datasets of 11 human participants acquired using the mGRE sequence. The datasets were first denoised by five different MCDnCNNs (Delevel1, 2, 3, 4 and DelevelMix), and subsequently their MWF maps were calculated and compared with the MWF maps directly calculated from the raw mGRE images without being denoised. Results: Experiments using the simulation data denoised by the appropriate MCDnCNN models showed that the standard deviation (SD) of the absolute error (AE) of the derived MWF results was significantly reduced (maximal reduction =15.5%, Level3 simulated noisy data, orientation angle =0, all the five MCDnCNN models). In the test using in vivo data, estimating MWF based on data particularly denoised by the appropriate MCDnCNN models was found to be the best, compared to otherwise not using the appropriate models. The results demonstrated that the appropriate MCDnCNN models may permit high-quality MWF mapping, i.e., substantial reduction of random variation in estimating MWF-maps while preserving accuracy and structural details. Conclusions: Appropriate MCDnCNN models as proposed may improve both the accuracy and precision in estimating MWF maps, thereby making it a more clinically feasible alternative.

The Role of Honey Bee Derived Aliphatic Esters in the Host-Finding Behavior of Varroa destructor.

Varroa destructor is an obligate ectoparasite of honey bees and shifted from its original host Apis cerana to the new host Apis mellifera in the first half of the twentieth century. The host shift has resulted in a great threat to the health and survival of A. mellifera colonies worldwide. Chemical signals play a crucial role in all aspects of the Varroa life cycle, including host finding. However, the chemical cues that affect the host finding behavior of Varroa mites are still not fully understood. In this study, we systematically profiled the headspace volatiles of both worker and drone larvae of the two honey bee species by using solid phase micro-extraction coupled to gas chromatography-mass spectrometry (SPME-GC-MS), and then used electrophysiological recording and Y-tube olfactometer bioassay to study the potential roles of the selected compounds. The chemical profiling showed that there were four aliphatic esters, ethyl myristate (EM), methyl palmitate (MP), ethyl palmitate (EP), and ethyl oleate (EO) commonly detected from all four types of larval hosts. Among them, EM was a new substance identified from honey bee headspace volatiles. Results from electrophysiological recordings indicated that all the aliphatic esters could elicit significant responses of Varroa pit organs on its forelegs. Moreover, behavioral analyses revealed that EM could significantly attract V. destructor at a medium dosage (10 µg), while MP had no observable effect on the mites and both EP and EO were able to repel the parasites. Our findings suggest an important role of host-derived aliphatic esters in Varroa host finding, and provide new chemicals for Varroa monitoring and control.

Diffusion tensor imaging brain structural clustering patterns in major depressive disorder.

Using magnetic resonance diffusion tensor imaging data from 45 patients with major depressive disorder (MDD) and 41 healthy controls (HCs), network indices based on a 246-region Brainnetcome Atlas were investigated in the two groups, and in the MDD subgroups that were subgrouped based on their duration of the disease. Correlation between the network indices and the duration of illness was also examined. Differences were observed between the MDDS subgroup (short disease duration) and the HC group, but not between the MDD and HC groups. Compared with the HCs, the clustering coefficient (CC) values of MDDS were higher in precentral gyrus, and caudal lingual gyrus; the CC of MDDL subgroup (long disease duration) was higher in postcentral gyrus and dorsal granular insula in the right hemisphere. Network resilience analyses showed that the MDDS group was higher than the HC group, representing relatively more randomized networks in the diseased brains. The correlation analyses showed that the caudal lingual gyrus in the right hemisphere and the rostral lingual gyrus in the left hemisphere were particularly correlated with disease duration. The analyses showed that duration of the illness appears to have an impact on the networking patterns. Networking abnormalities in MDD patients could be blurred or hidden by the heterogeneity of the MDD clinical subgroups. Brain plasticity may introduce a recovery effect to the abnormal network patterns seen in patients with a relative short term of the illness, as the abnormalities may disappear in MDDL .

Factors that affect the duration of wearing disposable personal protective equipment by healthcare professionals in Wuhan during treatment of COVID-19 patients: An epidemiological study.

The purpose of this study of healthcare workers who cared for COVID-19 patients was to identify factors that affected the duration of wearing personal protective equipment (PPE). The results of this study will provide initial guidance to practicing clinicians and a foundation for further research on this topic. This cross-sectional study examined 139 frontline healthcare professionals who worked at a single hospital in Wuhan, China, from March 16 to April 1, 2020. General and demographic data, physical and mental status, use of personal protective equipment, type of hospital work, and duration of wearing personal protective equipment were recorded. The mean duration of wearing personal protective equipment was 194.17 min (standard deviation: 3.71). Multiple linear regression analysis indicated that the duration of wearing personal protective equipment was significantly associated with the presence of a chronic disease, working hours when feeling discomfort, lack of patient cooperation and subsequent psychological pressure, prolonged continuous wearing of personal protective equipment, feeling anxious about physical strength, and the presence of fatigue when wearing personal protective equipment. These factors should be considered by practicing healthcare professionals and in future studies that examine the optimal duration of wearing personal protective equipment.

The effectiveness of diaphragmatic breathing relaxation training for improving sleep quality among nursing staff during the COVID-19 outbreak: a before and after study.

OBJECTIVES: Recent studies have demonstrated that first-line nurses involved in the coronavirus disease-2019 (COVID-19) crisis may experience sleep disturbances. As breathing relaxation techniques can improve sleep quality, anxiety, and depression, the current study aimed to evaluate the effectiveness of diaphragmatic breathing relaxation training (DBRT) for improving sleep quality among nurses in Wuhan, China during the COVID-19 outbreak. METHODS: This study used a quasi-experimental (before and after) intervention strategy, with 151 first-line nurses from four wards in Leishenshan hospital. The Pittsburgh Sleep Quality Index (PSQI), Self-Rating Anxiety Scale (SAS), and Self-Rating Depression Scale (SDS) to evaluate the effectiveness of DBRT before and after the intervention. Data were examined using the Shapiro-Wilk test, Levene's test, and paired t-test. RESULTS: A total of 140 nurses completed the DBRT sessions. First-line nurses achieved significant reductions in global sleep quality (p < 0.01), subjective sleep quality (p < 0.001), sleep latency (p < 0.01), sleep duration (p < 0.001), sleep disturbances (p < 0.001), habitual sleep efficiency (p = 0.015), daytime dysfunction (p = 0.001), and anxiety (p = 0.001). There were no significant reductions in the use of sleeping medication (p = 0.134) and depression (p = 0.359). CONCLUSION: DBRT is a useful non-pharmacological treatment for improving sleep quality and reducing anxiety among first-line nurses involved in the COVID-19 outbreak. The study protocol was clinically registered by the Chinese Clinical Trial Registry. CLINICAL TRIAL REGISTRATION NUMBER: ChiCTR2000032743.

Prevalence and Demographic Correlates of Poor Sleep Quality Among Frontline Health Professionals in Liaoning Province, China During the COVID-19 Outbreak.

BACKGROUND: Little empirical evidence is known about the sleep quality of frontline health professionals working in isolation units or hospitals during the novel coronavirus disease (COVID-19) outbreak in China. This study thus aimed to examine the prevalence of poor sleep quality and its demographic and correlates among frontline health professionals. METHODS: This is a multicenter, cross-sectional survey conducted in Liaoning province, China. Sleep quality was measured by the Pittsburgh Sleep Quality Index (PSQI). RESULTS: A total of 1,931 frontline health professionals were recruited. The prevalence of poor sleep quality was 18.4% (95%CI: 16.6%-20.11%). Multivariate logistic regression analysis found that older age (OR=1.043, 95%CI=1.026-1.061, P < 0.001), being nurse (OR=3.132, 95%CI=1.727-5.681, P < 0.001), and working in outer emergency medical team (OR=1.755, 95%CI=1.029-3.064, P=0.039) were positively associated with poor sleep quality. Participants who were familiar with crisis response knowledge were negatively associated with poor sleep quality (OR=0.70, 95%CI=0.516-0.949, P=0.021). CONCLUSION: The prevalence of poor sleep quality was relatively low among frontline health professionals during the COVID-19 epidemic. Considering the negative impact of poor sleep quality on health professionals' health outcomes and patient outcomes, regularly screening and timely treatments are warranted to reduce the likelihood of poor sleep quality in health professionals.

Electroless Deposition of Automatically Shedded Thin Copper Foils.

Electroless deposition (ELD) is a process widely used for the production of thin metal films, but stripping the films from the substrate remains challenging. Here, we report a low-cost ELD method for the large-scale production of freestanding copper (Cu) foils in a short time of 25-55 min. By atomizing a thin (<100 nm) sacrificial layer of chitosan with weak glycosyl bonds and a high degree of deacetylation on the glass substrate, the chitosan is completely decomposed in the process of Cu-deposition, producing automatically shedded Cu foils with varied thicknesses from 746 nm to 8.33 µm and high elastic modulus. When used as battery current collectors, the thin Cu foils with enhanced adhesive fastness and contact areas greatly enhance the capacity and rate capability of graphite anodes. Compared with the commercial Cu current collectors, both the battery capacity and energy density are increased by 429.6 and 484.1%, respectively. The reported approach can be extended for fabricating other metal foils such as nickel with properties appealing for applications.

The Effect of Auditory Verbal Hallucinations on the Relationship between Spontaneous Brain Activity and intraventricular Brain Temperature in Patients with Drug-Naïve Schizophrenia.

Our recent study reported that adolescent-onset schizophrenia showed an uncoupling between intraventricular brain temperature (iBT) and local spontaneous brain activity (SBA). While auditory verbal hallucinations (AVH) are common in schizophrenia, the role of AVH in the iBT-SBA relationship is unclear. The current study recruited 24 drug-naïve schizophrenia patients with AVH, 20 patients without AVH and 30 matched healthy controls (HC). We used a diffusion-weighted imaging (DWI) based thermometry method to calculate the iBT for each participant and used both regional homogeneity and amplitude of low-frequency fluctuation methods to assess the SBA. One-way ANOVA was used to detect group differences in iBT, and a partial correlation analysis controlling for lateral ventricles volume, sex and age was applied to detect the relationships between iBT and SBA across the three groups. The results demonstrated that the AVH group showed a significant coupling between iBT and SBA in the bilateral lingual gyrus, left superior occipital gyrus and caudate compared with the other two groups, and no uncoupling was found in the two patients groups relative to HCs. These findings suggest that AVH may modulate the relationship between iBT and SBA in schizophrenia-related regions.

Erratum to "Withdrawal notice to the effectiveness of diaphragmatic breathing relaxation training for improving sleep quality among nursing staff during the COVID-19 outbreak: a before and after study" [Sleep Medicine X (2) (2020) 100026].

[This corrects the article DOI: 10.1016/j.sleepx.2020.100026.].

The Reorganization of Resting-State Brain Networks Associated With Motor Imagery Training in Chronic Stroke Patients.

A number of studies have suggested that motor imagery training (MIT) has a positive influence on the upper extremity motor recovery in stroke patients, but little is known about its neural basis. To investigate the cortical motor network plasticity after MIT, 34 chronic hemiplegic subjects with subcortical stroke were recruited and randomly allocated to either the conventional rehabilitation therapy (CRT) or the CRT + MIT. The patients were assessed with the upper limb section of Fugl-Meyer assessment Scale (FM-UL) and resting-state fMRI before and after the 4 weeks of treatment. Seed-based functional connectivity (FC) of the ipsilesional primary motor cortex (M1) and graph-theory based analysis were used to explore the relationships between the motor recovery and reorganization of motor networks. We found that the patients in the MIT group showed more improvement in the FM-UL scores compared with the CRT group. Both groups presented increased inter-hemispheric and decreased intra-hemispheric FC of the ipsilesional M1 after intervention. However, the MIT group showed increased FC of the ipsilesional M1 with the ipsilesional precentral and postcentral gyri, middle cingulate gyrus and supramarginal gyrus after intervention, while the CRT group showed decreased FC in these regions. In addition, the clustering coefficient was significantly increased in the MIT group but not in the CRT group, and the increment of clustering coefficient was significantly positively correlated with improvement of FM-UL scores. Therefore, MIT might contribute to the motor recovery in stroke patients through the following network reorganization, i.e., promoting the efficiency of regional neuronal communication and the reorganization of intrinsic FC of the ipsilesional M1 involving widely distributed motor network in both hemispheres.

A theoretical insight into the reaction mechanisms of a 2,4,6-trinitrotoluene nitroso metabolite with thiols for toxic effects.

2,4,6-Trinitrotoluene (TNT) is a class C carcinogen as rated by the Environmental Protection Agency. One of the toxicity mechanisms of TNT is the covalent binding of its metabolites to critical proteins. However, knowledge about their molecular reaction mechanisms is scarce. Herein, we have provided density functional theory (DFT) simulation evidences for the reaction mechanisms of the nitroso metabolite of TNT with the sulfhydryl group of model thiols for the first time. The results show that the solvent-mediated proton-transfer mechanism plays a significant role in the entire process. For the formation of semimercaptal, the mechanism is slightly different from the previous one where the thiolate anion attacks the nitroso group. The rearrangement of semimercaptal needs to be triggered by an acid or hydrated ion (H3O+), which is consistent with the previous assumption. The other pathway, the conversion of semimercaptal to hydroxylamine, has to overcome a higher barrier, although it does not need the participation of an acid or a hydrated ion. In addition, the details on transition states, intermediates and free energy surfaces for three reactions are given, which make up for the lack of experimental knowledge. These conclusions can help to deeply understand the toxic effects of TNT and other nitroaromatic explosives.

Altered coupling of spontaneous brain activities and brain temperature in patients with adolescent-onset, first-episode, drug-naïve schizophrenia.

PURPOSE: A recent study has reported that schizophrenia patients show an uncoupled association between intraventricular brain temperature (BT) and cerebral blood flow (CBF). CBF has been found to be closely coupled with spontaneous brain activities (SBAs) derived from resting-state BOLD fMRI metrics. Yet, it is unclear so far whether the relationship between the intraventricular BT and the SBAs may change in patients with adolescent-onset schizophrenia (AOS) compared with that in healthy controls (HCs). METHODS: The present study recruited 28 first-episode, drug-naïve AOS patients and 22 matched HCs. We measured the temperature of the lateral ventricles (LV) using diffusion-weighted imaging thermometry and measured SBAs using both regional homogeneity and amplitude of low-frequency fluctuation methods. A nonparametric Wilcoxon rank sum test was used to detect the difference in intraventricular BT between AOS patients and HCs with LV volume, age, and sex as covariates. We also evaluated the relationship between the intraventricular BT and the SBAs using partial correlation analysis controlling for LV volume, age, and sex. RESULTS: We found that HCs showed a significant negative correlation between the intraventricular BT and the local SBAs in the bilateral putamina and left superior temporal gyrus, while such a correlation was absent in AOS patients. Additionally, no significant difference between the two groups was found in the intraventricular BT. CONCLUSION: These findings suggest that AOS patients may experience an uncoupling between intraventricular BT and SBAs in several schizophrenia-related brain areas, which may be associated with the altered relationships among intraventricular BT, CBF, and metabolism.

Altered intra- and inter-network functional coupling of resting-state networks associated with motor dysfunction in stroke.

Motor functions are supported through functional integration across the extended motor system network. Individuals following stroke often show deficits on motor performance requiring coordination of multiple brain networks; however, the assessment of connectivity patterns after stroke was still unclear. This study aimed to investigate the changes in intra- and inter-network functional connectivity (FC) of multiple networks following stroke and further correlate FC with motor performance. Thirty-three left subcortical chronic stroke patients and 34 healthy controls underwent resting-state functional magnetic resonance imaging. Eleven resting-state networks were identified via independent component analysis (ICA). Compared with healthy controls, the stroke group showed abnormal FC within the motor network (MN), visual network (VN), dorsal attention network (DAN), and executive control network (ECN). Additionally, the FC values of the ipsilesional inferior parietal lobule (IPL) within the ECN were negatively correlated with the Fugl-Meyer Assessment (FMA) scores (hand + wrist). With respect to inter-network interactions, the ipsilesional frontoparietal network (FPN) decreased FC with the MN and DAN; the contralesional FPN decreased FC with the ECN, but it increased FC with the default mode network (DMN); and the posterior DMN decreased FC with the VN. In sum, this study demonstrated the coexistence of intra- and inter-network alterations associated with motor-visual attention and high-order cognitive control function in chronic stroke, which might provide insights into brain network plasticity following stroke.

[Epidemiological characteristics of imported malaria in Sichuan Province in 2015].

Objective: To analyze the epidemiological characteristics of imported malaria in Sichuan Province in 2015 in the aim of providing scientific basis for malaria control. Methods: The epidemiological data of malaria in Sichuan Province reported through the Infectious Disease Reporting and Management System of China Information System for Disease Control and Prevention in 2015 were collected and analyzed. Results: In 2015,290 malaria cases were reported in Sichuan Provinc, consisting of 158 falciparum malaria cases (54.5%),107 vivax malaria cases (36.9%),14 ovale malaria cases (4.8%), one quartan malaria case(0.3%), and 10 mixed infections of vivax malaria and falciparum malaria (3.5%). Five cases of falciparum malaria died. The reported cases were all imported, with a major source of Africa (271, 93.4%), in which Ethiopia (83) and Angola (49) were two major sources. The cases were reported continuously from January to December, with the majority(139, 47.9%) being reported in December, August, June and July. The cases distributed mainly in Guangan, Chengdu, Nanchong, Mianyang, Deyang, Luzhou and Suining(243, 83.8%). Among the 209 cases who first visited medical units after onset, 118 cases were diagnosed as malaria, the misdiagnosis rate at first visit was 43.5%(91/209). Conclusion: The malaria cases reported in Sichuan Province in 2015 are all imported from overseas, mainly infected with P. falciparum and P. vivax, and imported mostly from Africa. There is a high rate of misdiagnosis in medical units in Sichuan Province.

Robust aptamer-polydopamine-functionalized M-PLGA-TPGS nanoparticles for targeted delivery of docetaxel and enhanced cervical cancer therapy.

One limitation of current biodegradable polymeric nanoparticles (NPs) is the contradiction between functional modification and maintaining formerly excellent bioproperties with simple procedures. Here, we reported a robust aptamer-polydopamine-functionalized mannitol-functionalized poly(lactide-co-glycolide) (M-PLGA)-D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) nanoformulation (Apt-pD-NPs) for the delivery of docetaxel (DTX) with enhanced cervical cancer therapy effects. The novel DTX-loaded Apt-pD-NPs possess satisfactory advantages: 1) increased drug loading content and encapsulation efficiency induced by star-shaped copolymer M-PLGA-TPGS; 2) significant active targeting effect caused by conjugated AS1411 aptamers; and 3) excellent long-term compatibility by incorporation of TPGS. Therefore, with simple preparation procedures and excellent bioproperties, the new functionalized Apt-pD-NPs could maximally increase the local effective drug concentration on tumor sites, achieving enhanced treatment effectiveness and minimizing side effects. In a word, the robust DTX-loaded Apt-pD-NPs could be used as potential nanotherapeutics for cervical cancer treatment, and the aptamer-polydopamine modification strategy could be a promising method for active targeting of cancer therapy with simple procedures.

Expression of hyperpolarization-activated cyclic nucleotide-gated channel isoforms in a canine model of atrial fibrillation.

The aim of the present study was to analyze the mRNA and protein expression levels of atrial hyperpolarization-activated cyclic nucleotide-gated (HCN) channel isoforms in the left atrial muscle of dogs with multiple organ failure. A total of 14 beagle dogs with multiple organ failure, including seven cases with sinus rhythm and seven cases with atrial fibrillation (AF), underwent surgery to remove a sample of left atrial appendage tissue. The expression levels of a number of HCN channel subtypes were subsequently measured using quantitative polymerase chain reaction and western blot analysis. The mRNA and protein expression levels of HCN2 and HCN4 increased significantly in the AF group when compared with the sinus rhythm group. However, expression of the HCN1 isoform was not detected. Therefore, increased expression levels of HCN2 and HCN4 may be important molecular mechanisms in the pathogenesis of AF, which were associated with differences in patients with valvular heart disease.

[Study on the Lateral Growth of Ag Nanowires and Its Inhibition].

Ag nanowires (Ag NWs) are synthesized by polyol method under the conditions of different temperature of reaction solution, different addition amount and injection rate of polyvinylpyrrolidone (PVP). The structure and the process of lateral growth of Ag NWs were observed and analyzed by X-ray diffraction (XRD), ultraviolet-visible absorption spectrum (UV-VIS), scanning electron microscopy (SEM) and transmission electron microscope (TEM). It showed that the lateral growth of Ag NWs and longitudinal growth of Ag NWs occurrs at the same time by UV-VIS. And in the later stage of synthesis of Ag NWs, the peak in UV-VIS, which indicated the lateral growth of Ag NWs, red-shifted obviously from 384 nm to 388 nm. This rapid redshift implied that the diameters of Ag NWs increased quickly. In other words, rapid lateral growth of Ag NWs occurred in the later stage of synthesis of Ag NWs. According to the SEM of Ag NWs, in the early stage of the reaction (15~23 min), the diameter of Ag NWs increased by only 20 nm, but in the later stage of reaction (23~30 min), the diameter of Ag NWs increased by nearly 150 nm. The result of SEM observation is consistent with the analysis of UV-VIS. It was also found that the lateral growth of Ag NWs is related not only to the sizes of seeds but also to the thicknesses of the outer Ag layers. Tiny Ag particles with diameters of several nanometers adsorbed onto the side facets of Ag NWs and acted as adsorption points for Ag source. The lateral growth of Ag NWs was caused by the continuous multipoint adsorption of Ag source on the side of Ag NWs. Decreasing the temperature of the reaction solution (from 165 to 155 degree), reducing the injection rate (from 67 to 49 mL·h-1) and the addition amount of PVP in the later stage could inhibit the lateral growth of Ag NWs and increase the aspect ratios of Ag NWs remarkably. The diameters of Ag NWs decreased from 200 nm to 100 nm, but their lengths still maintained above 100 µm.