Pre-fusion motion state determines the heterogeneity of membrane fusion dynamics for large dense-core vesicles

AIM

In neuroendocrine cells, large dense-core vesicles (LDCVs) undergo highly regulated pre-fusion processes before releasing hormones via membrane fusion. Significant heterogeneity has been found for LDCV population based on the dynamics of membrane fusion. However, how the pre-fusion status impacts the heterogeneity of LDCVs still remains unclear. Hence, we explored pre-fusion determinants of heterogeneous membrane fusion procedure of LDCV subpopulations.

METHODS

We assessed the pre-fusion motion of two LDCV subpopulations with distinct membrane fusion dynamics individually, using total internal reflection fluorescence microscopy. These two subpopulations were isolated by blocking Rho GTPase-dependent actin reorganization using Clostridium difficile toxin B (ToxB), which selectively targets the fast fusion vesicle pool.

RESULTS

We found that the fast fusion subpopulation was in an active motion mode prior to release, termed "active" LDCV pool, while vesicles from the slow fusion subpopulation were also moving but in a significantly more confined status, forming an "inert" pool. The depletion of the active pool by ToxB also eliminated fast fusion vesicles and was not rescued by pre-treatment with phorbol ester. A mild actin reorganization blocker, latrunculin A, that partially disrupted the active pool, only slightly attenuated the fast fusion subpopulation.

CONCLUSION

The pre-fusion motion state of LDCVs also exhibits heterogeneity and dictates the heterogeneous fusion pore dynamics. Rearrangement of F-actin network mediates vesicle pre-fusion motion and subsequently determines the membrane fusion kinetics.

Machine learning based longitudinal virtual diagnostics at SwissFEL

The bunch length in a linac driven Free Electron Laser (FEL) is a major parameter to be characterized to optimize the final accelerator performance. In linear machines, this observable is typically determined from the beam imaged on a screen located downstream of a Transverse Deflecting Structure (TDS) used to impinge a time dependent kick along the longitudinal coordinate of the beam. This measurement is typically performed during the machine setup and only sporadically to check the beam duration, but it cannot be continuously repeated because it is time consuming and invasive. A non-invasive method to determine the electron bunch length has already been presented in the past. This method is based on the analysis of the synchrotron radiation light spot emitted by the bunch passing through a magnetic chicane, provided that the energy chirp impinged on the bunch by the upstream radio frequency structures is known. In order to overcome a systematic discrepancy affecting the synchrotron radiation monitor based results compared to the absolute TDS based ones, we implemented and optimized a machine learning approach to predict the bunch length downstream of the two SwissFEL compression stages-from about 10 fs up to about 2 ps-as well as the beam longitudinal profile at the first one.

Identification of a Prognostic Signature for Ovarian Cancer Based on Ubiquitin-Related Genes Suggesting a Potential Role for FBXO9

BACKGROUND

Ovarian cancer (OV) is associated with high mortality and poses challenges in diagnosis and prognosis prediction. Ubiquitin-related genes (UbRGs) are involved in the initiation and progression of cancers, but have still not been utilized for diagnosis and prognosis of OV.

METHODS

K48-linked ubiquitination in ovarian tissues from our OV and control cohort was assessed using immunohistochemistry. UbRGs, including ubiquitin and ubiquitin-like regulators, were screened based on the TCGA-OV and GTEx database. Univariate Cox regression analysis identified survival-associated UbRGs. A risk model was established using the LASSO regression and multivariate Cox regression analysis. The relationship between UbRGs and immune cell infiltration, tumor mutational burden, drug sensitivity, and immune checkpoint was determined using the CIBERSORT, ESTIMATE, and Maftools algorithms, based on the Genomics of Drug Sensitivity in Cancer and TCGA-OV databases. GEPIA2.0 was used to analyze the correlation between FBXO9/UBD and DNA damage repair-related genes. Finally, FBXO9 and UBD were accessed in tissues or cells using immunohistochemistry, qPCR, and Western blot.

RESULTS

We confirmed the crucial role for ubiquitination in OV as a significant decrease of K48-linked ubiquitination was observed in primary OV lesions. We identified a prognostic signature utilizing two specific UbRGs, FBXO9 and UBD. The risk score obtained from this signature accurately predicted the overall survival of TCGA-OV training dataset and GSE32062 validation dataset. Furthermore, this risk score also showed association with immunocyte infiltration and drug sensitivity, revealing potential mechanisms for ubiquitination mediated OV risk. In addition, FBXO9, but not UBD, was found to be downregulated in OV and positively correlated with DNA damage repair pathways, suggesting FBXO9 as a potential cancer suppressor, likely via facilitating DNA damage repair.

CONCLUSIONS

We identified and validated a signature of UbRGs that accurately predicts the prognosis, offers valuable guidance for optimizing chemotherapy and targeted therapies, and suggests a potential role for FBXO9 in OV.

The subfamily Xerocomoideae (Boletaceae, Boletales) in China

Xerocomoideae is an ecologically and economically important Boletaceae subfamily (Boletales) comprising 10 genera. Although many studies have focused on Xerocomoideae in China, the diversity, taxonomy and molecular phylogeny still remained incompletely understood. In the present study, taxonomic and phylogenetic studies on Chinese species of Xerocomoideae were carried out by morphological examinations and molecular phylogenetic analyses. Eight genera in Xerocomoideae, viz. Aureoboletus, Boletellus, Heimioporus, Hemileccinum, Hourangia, Phylloporus, Pulchroboletus, and Xerocomus were confirmed to be distributed in China; 97 species of the subfamily were accepted as being distributed in China; one ambiguous taxon was tentatively named Bol. aff. putuoensis; two synonyms, viz. A. marroninus and P. dimorphus were defined. Among the Chinese accepted species, 13 were newly described, viz. A. albipes, A. conicus, A. ornatipes, Bol. erythrolepis, Bol. rubidus, Bol. sinochrysenteroides, Bol. subglobosus, Bol. zenghuoxingii, H. squamipes, P. hainanensis, Pul. erubescens, X. albotomentosus, and X. fuscatus, 36 known species were redescribed, and the other 48 species were reviewed. Keys to accepted species of Aureoboletus, Boletellus, Heimioporus, Hemileccinum, Hourangia, Phylloporus, and Xerocomus in China were also provided. Taxonomic novelties: New species: Aureoboletus albipes N.K. Zeng, Xu Zhang & Zhi Q. Liang, A. conicus N.K. Zeng, Xu Zhang & Zhi Q. Liang, A. ornatipes N.K. Zeng, Xu Zhang & Zhi Q. Liang, Boletellus erythrolepis N.K. Zeng, R. Xue, S. Jiang & Zhi Q. Liang, Bol. rubidus N.K. Zeng, R. Xue, Y.J. Hao & Zhi Q. Liang, Bol. sinochrysenteroides N.K. Zeng, R. Xue & Kuan Zhao, Bol. subglobosus N.K. Zeng, R. Xue, S. Jiang & Zhi Q. Liang, Bol. zenghuoxingii N.K. Zeng, R. Xue, S. Jiang & Zhi Q. Liang, Hemileccinum squamipes N.K. Zeng, Chang Xu & Zhi Q. Liang, Phylloporus hainanensis N.K. Zeng, L.L. Wu, & Zhi Q. Liang, Pulchroboletus erubescens N.K. Zeng, Chang Xu & Zhi Q. Liang, Xerocomus albotomentosus N.K. Zeng, H.J. Xie, Chang Xu & Zhi Q. Liang, and X. fuscatus N.K. Zeng, H.J. Xie, Chang Xu & Zhi Q. Liang. Citation: Xue R, Zhang X, Xu C, Xie HJ, Wu LL, Wang Y, Tang LP, Hao YJ, Zhao K, Jiang S, Li Y, Yang YY, Li Z, Liang ZQ, Zeng NK (2023). The subfamily Xerocomoideae (Boletaceae, Boletales) in China. Studies in Mycology 106: 95-197. doi: 10.3114/sim.2022.106.03.

Elastin-like recombinamer-mediated hierarchical mineralization coatings on Zr-16Nb-xTi (x = 4,16 wt%) alloy surfaces improve biocompatibility

The biocompatibility of biomedical materials is vital to their applicability and functionality. However, modifying surfaces for enhanced biocompatibility using traditional surface treatment techniques is challenging. We employed a mineralizing elastin-like recombinamer (ELR) self-assembling platform to mediate mineralization on Zr-16Nb-xTi (x = 4,16 wt%) alloy surfaces, resulting in the modification of surface morphology and bioactivity while improving the biocompatibility of the material. We modulated the level of nanocrystal organization by adjusting the cross-linker ratio. Nanoindentation tests revealed that the mineralized configuration had nonuniformity with respect to Young's modulus and hardness, with the center areas having higher values (5.626 ± 0.109 GPa and 0.264 ± 0.022 GPa) compared to the edges (4.282 ± 0.327 GPa and 0.143 ± 0.023 GPa). The Scratch test results indicated high bonding strength (2.668 ± 0.117 N) between the mineralized coating and the substrate. Mineralized Zr-16Nb-xTi (x = 4,16 wt%) alloys had higher viability compared to untreated alloys, which exhibited high cell viability (>100 %) after 5 days and high alkaline phosphatase activity after 7 days. Cell proliferation assays indicated that MG 63 cells grew faster on mineralized surfaces than on untreated surfaces. Scanning electron microscopy imaging confirmed that the cells adhered and spread well on mineralized surfaces. Furthermore, hemocompatibility test results revealed that all mineralized samples were non-hemolytic. Our results demonstrate the viability of employing the ELR mineralizing platform to improve alloy biocompatibility.

Instantaneous 4D micro-particle image velocimetry (µPIV) via multifocal microscopy (MUM)

Multifocal microscopy (MUM), a technique to capture multiple fields of view (FOVs) from distinct axial planes simultaneously and on one camera, was used to perform micro-particle image velocimetry (µPIV) to reconstruct velocity and shear stress fields imposed by a liquid flowing around a cell. A diffraction based multifocal relay was used to capture images from three different planes with 630 nm axial spacing from which the axial positions of the flow-tracing particles were calculated using the image sharpness metric. It was shown that MUM can achieve an accuracy on the calculated velocity of around (0.52 ± 0.19) µm/s. Using fixed cells, MUM imaged the flow perturbations at sub-cellular level, which showed characteristics similar to those observed in the literature. Using live cells as an exemplar, MUM observed the effect of changing cell morphology on the local flow during perfusion. Compared to standard confocal laser scanning microscope, MUM offers a clear advantage in acquisition speed for µPIV (over 300 times faster). This is an important characteristic for rapidly evolving biological systems where there is the necessity to monitor in real time entire volumes to correlate the sample responses to the external forces.

A two-subpopulation model that reflects heterogeneity of large dense core vesicles in exocytosis

Exocytosis of large dense core vesicles is responsible for hormone secretion in neuroendocrine cells. The population of primed vesicles ready to release upon cell excitation demonstrates large heterogeneity. However, there are currently no models that clearly reflect such heterogeneity. Here, we develop a novel model based on single vesicle release events from amperometry recordings of PC12 cells using carbon fiber microelectrode. In this model, releasable vesicles can be grouped into two subpopulations, namely, SP1 and SP2. SP1 vesicles replenish quickly, with kinetics of ~0.0368 s^-1, but likely undergo slow fusion pore expansion (amperometric signals rise at ~2.5 pA/ms), while SP2 vesicles demonstrate slow replenishment (kinetics of ~0.0048 s^-1) but prefer fast dilation of fusion pore, with an amperometric signal rising rate of ~9.1 pA/ms. Phorbol ester enlarges the size of SP2 partially via activation of protein kinase C and conveys SP1 vesicles into SP2. Inhibition of Rho GTPase-dependent actin rearrangement almost completely depletes SP2. We also propose that the phorbol ester-sensitive vesicle subpopulation (SP2) is analogous to the subset of superprimed synaptic vesicles in neurons. This model provides a meticulous description of the architecture of the readily releasable vesicle pool and elucidates the heterogeneity of the vesicle priming mechanism.

Propofol ameliorates acute postoperative fatigue and promotes glucagon-regulated hepatic gluconeogenesis by activating CREB/PGC-1α and accelerating fatty acids beta-oxidation

Postoperative fatigue (POF) is the most common and long-lasting complication after surgery, which brings heavy burden to individuals and society. Recently, hastening postoperative recovery receives increasing attention, but unfortunately, the mechanisms underlying POF remain unclear. Propofol is a wildly used general anesthetic in clinic, and inspired by the rapid antidepressant effects induced by ketamine at non-anesthetic dose, the present study was undertaken to investigate the anti-fatigue effects and underlying mechanisms of propofol at a non-anesthetic dose in 70% hepatectomy induced POF model in rats. We first showed here that single administration of propofol at 0.1 mg/kg ameliorated acute POF in hepatectomy induced POF rats. Based on metabonomics analysis, we hypothesized that propofol exerted anti-fatigue activity in POF rats by facilitating free fatty acid (FFA) oxidation and gluconeogenesis. We further confirmed that propofol restored the deficit in FFA oxidation and gluconeogenesis in POF rats, as evidenced by the elevated FFA utilization, acetyl coenzyme A content, pyruvic acid content, phosphoenolpyruvic acid content, hepatic glucose output and glycogen storage. Moreover, propofol stimulated glucagon secretion and up-regulated expression of cAMP-response element binding protein (CREB), phosphorylated CREB, peroxlsome prolifeator-activated receptor-γ coactivator-1α (PGC-1α), phosphoenolpyruvate carboxykinade1 and carnitine palmitoltransferase 1A. In summary, our study suggests for the first time that propofol ameliorates acute POF by promoting glucagon-regulated gluconeogenesis via CREB/PGC-1α signaling and accelerating FFA beta-oxidation.

Activated or Impaired: An Overview of DNA Repair in Neurodegenerative Diseases

As the population ages, age-related neurodegenerative diseases have become a major challenge in health science. Currently, the pathology of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease, is still not fully understood. Remarkably, emerging evidence indicates a role of genomic DNA damage and repair in various neurodegenerative disorders. Here, we summarized the current understanding of the function of DNA damage repair, especially base excision repair and double strand break repair pathways, in a variety of neurodegenerative diseases. We concluded that exacerbation of DNA lesions is found in almost all types of neurodegenerative diseases, whereas the activities of different DNA repair pathways demonstrate distinct trends, depending on disease type and even brain region. Specifically, key enzymes involved in base excision repair are likely impaired in Alzheimer's disease and amyotrophic lateral sclerosis but activated in Parkinson's disease, while nonhomologous end joining is likely downregulated in most types of neurodegenerative diseases. Hence, impairment of nonhomologous end joining is likely a common etiology for most neurodegenerative diseases, while defects in base excision repair are likely involved in the pathology of Alzheimer's disease and amyotrophic lateral sclerosis but are Parkinson's disease, based on current findings. Although there are still discrepancies and further studies are required to completely elucidate the exact roles of DNA repair in neurodegeneration, the current studies summarized here provide crucial insights into the pathology of neurodegenerative diseases and may reveal novel drug targets for corresponding neurodegenerative diseases.

The Role of Calmodulin vs. Synaptotagmin in Exocytosis

Exocytosis is a Ca²⁺-regulated process that requires the participation of Ca²⁺ sensors. In the 1980s, two classes of Ca²⁺-binding proteins were proposed as putative Ca²⁺ sensors: EF-hand protein calmodulin, and the C2 domain protein synaptotagmin. In the next few decades, numerous studies determined that in the final stage of membrane fusion triggered by a micromolar boost in the level of Ca²⁺, the low affinity Ca²⁺-binding protein synaptotagmin, especially synaptotagmin 1 and 2, acts as the primary Ca²⁺ sensor, whereas calmodulin is unlikely to be functional due to its high Ca²⁺ affinity. However, in the meantime emerging evidence has revealed that calmodulin is involved in the earlier exocytotic steps prior to fusion, such as vesicle trafficking, docking and priming by acting as a high affinity Ca²⁺ sensor activated at submicromolar level of Ca²⁺. Calmodulin directly interacts with multiple regulatory proteins involved in the regulation of exocytosis, including VAMP, myosin V, Munc13, synapsin, GAP43 and Rab3, and switches on key kinases, such as type II Ca²⁺/calmodulin-dependent protein kinase, to phosphorylate a series of exocytosis regulators, including syntaxin, synapsin, RIM and Ca²⁺ channels. Moreover, calmodulin interacts with synaptotagmin through either direct binding or indirect phosphorylation. In summary, calmodulin and synaptotagmin are Ca²⁺ sensors that play complementary roles throughout the process of exocytosis. In this review, we discuss the complementary roles that calmodulin and synaptotagmin play as Ca²⁺ sensors during exocytosis.

Sevoflurane impedes the progression of glioma through modulating the circular RNA has_circ_0012129/miR-761/TGIF2 axis

OBJECTIVE

Glioma is a highly aggressive and lethal brain tumor. Anesthetics have been shown to have important effects on the biological characteristics of cancer cells. Nevertheless, the molecular mechanism of anesthetic-mediated glioma cells progression remains unclear.

MATERIALS AND METHODS

Sevoflurane (sev) was employed to treat glioma cells. The biological characteristics (viability, colony formation, apoptosis, cell cycle, migration, and invasion) of glioma cells were determined via Cell Counting Kit-8 (CCK-8), cell colony formation, flow cytometry, PI cytometry, or transwell assays. The protein levels of Cell Cycle Dependent Kinase (CDK) 2, CDK4, E-cadherin, N-cadherin, Vimentin, and Transforming Growth Factor Beta (TGFB) induced factor homeobox 2 (TGIF2) were assessed through Western blot analysis. Glucose consumption and lactate production were measured using special commercial kits. The expression of circular RNA has_circ_0012129 (circ_0012129) and miR-761 was detected via quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The relationship between circ_0012129 or TGIF2 and miR-761 was verified with Dual-Luciferase reporter assay. Sevoflurane-mediated molecular mechanisms have been confirmed via xenograft assay.

RESULTS

Sevoflurane suppressed viability, colony formation, cell cycle, migration, and invasion and promoted apoptosis of glioma cells in vitro, and impeded tumor growth in vivo. Circ_0012129 and TGIF2 were downregulated and miR-761 was upregulated in sevoflurane-treated glioma cells. Circ_0012129 elevation abolished sevoflurane-mediated biological characteristics of glioma cells. MiR-761 served as target for circ_0012129 and miR-761 targeted TGIF2. Moreover, both miR-761 overexpression and TGIF2 suppression restored circ_0012129 enhancement-mediated biological characteristics of sevoflurane-treated glioma cells.

CONCLUSIONS

Sevoflurane mediated the progression of glioma via regulating the circ_0012129/miR-761/TGIF2 axis.

Effect of NT-3 on repair of spinal cord injury through the MAPK signaling pathway

OBJECTIVE

The aim of this study was to explore the effect of neurotrophin-3 (NT-3) on the repair of spinal cord injury (SCI) through the mitogen-activated protein kinase (MAPK) signaling pathway.

MATERIALS AND METHODS

The rat model of SCI was first successfully established using the impactor (SCI group). Meanwhile, control group and NT-3 treatment group were set up as well. Basso-Beattie-Bresnahan (BBB) score was given and blood, and spinal cord tissues were collected from rats. Subsequently, serum indexes were detected, including glucose (Glu), creatinine (Cr), K+, Na+, the content of interleukin-6 (IL-6), IL-1β, tumor necrosis factor-β (TNF-β), and the level of myeloperoxidase (MPO). Moreover, the morphological changes were observed via hematoxylin-eosin (HE) staining. The gene and protein expressions of glial fibrillary acidic protein (GFAP) and MAPK were determined through Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and Western blotting, respectively. Furthermore, the effect of the MAPK signaling pathway on SCI was comprehensively observed.

RESULTS

In SCI group, the rats could not crawl autonomously with the loss of motor function and paraplegia. Meanwhile, the levels of Glu, Cr, Na+, IL-6, IL-1β, TNF-β, and MPO were all significantly up-regulated. According to the results of HE staining, spinal nerve fibers disappeared with significant syringomyelia in SCI group. Meanwhile, the aggregation of nerve fibers was observed without apparent tissue bleeding, edema, and cell deformation in NT-3 group. QRT-PCR results demonstrated that SCI group showed remarkably higher levels of GFAP, MAPK, and c-Jun N-terminal kinase (JNK) (p<0.05), while it showed a markedly lower level of ERK2 than NT-3 group (p<0.05). In NT-3 group, the protein expression of MAPK in myocardial tissues was remarkably lower than that of SCI group (p<0.05).

CONCLUSIONS

NT-3 can inhibit the MAPK signaling pathway, thereby promoting the repair of SCI.

Lycorine hydrochloride suppresses stress-induced premature cellular senescence by stabilizing the genome of human cells

Lycorine, a natural compound isolated from the traditional Chinese medicinal herb Lycoris radiata, exhibits multiple pharmacological effects, such as anti-inflammatory, antiviral, and anticancer effects. Accumulating evidence also indicates that lycorine might hold the potential to treat age-associated Alzheimer's disease. However, whether lycorine is involved in delaying the onset of cellular senescence and its underlying mechanisms has not been determined. Here, we demonstrate that the salt of lycorine, lycorine hydrochloride, significantly suppressed stress-induced premature cellular senescence (SIPS) by ~2-fold, as determined by senescence-associated beta-galactosidase (SA-β-gal) staining and the expression of p16 and p21. In addition, pretreating cells with lycorine hydrochloride significantly inhibited the expression of CXCL1 and IL1α, two factors of the senescence-associated secreted phenotype (SASP) in SIPS cells. Further experiments revealed that lycorine hydrochloride promoted both the homologous recombination (HR) and nonhomologous end joining (NHEJ) pathways of DNA double-strand break (DSB) repair. Mechanistic studies suggested that lycorine hydrochloride treatment promoted the transcription of SIRT1 and SIRT6, critical longevity genes positively regulating both HR and NHEJ repair pathways, thereby stimulating DSB repair and stabilizing genomes. Inhibiting SIRT1 enzymatic activity abrogated the protective effect of lycorine hydrochloride on delaying the onset of SIPS, repairing DSBs, and restoring genome integrity. In summary, our work indicates that lycorine hydrochloride might hold therapeutic potential for treating age-associated diseases or promoting healthy aging by stabilizing genomes.

Novel Biocompatible Zr-Based Alloy with Low Young's Modulus and Magnetic Susceptibility for Biomedical Implants

The microstructure, mechanical properties, magnetic susceptibility, electrochemical corrosion performance, in vitro cell compatibility and blood consistency of Zr-16Nb-xTi (x = 0, 4, 8, 12 and 16 wt.%) materials were investigated as potential materials for biomedical implants. X-ray diffraction (XRD) and Transmission electron microscopy (TEM) analyses revealed the secondary phase martensite α' formed during the quenching process. The phase composition contained metastable β and martensite α', resulting from Ti addition. These phase constitutions were the main causes of a low Young's modulus and magnetic susceptibility. The in vitro cytocompatibility analysis illustrated that the MG63 cells maintained high activity (from 91% to 97%) after culturing in Zr-16Nb-xTi extraction media for 12 days due to the high internal biocompatibility of Zr, Nb and Ti elements, as well as the optimal corrosion resistance of Zr-16Nb-xTi. On the basis of Inductively coupled plasma optical emission spectrometry (ICP-OES) ion release studies, the concentration of Zr, Nb and Ti was noted to reach the equipment detective limit of 0.001 mg/L, which was much lower than pure Ti. With respect to the corrosion behavior in Hank's solution, Zr-16Nb-16Ti displayed superior properties, possessing the lowest corrosion current density and widest passivation region, attributed to the addition of Ti. The blood compatibility test illustrated that the Zr-16Nb-xTi materials were nonhemolytic, and the platelets maintained a spherical shape, with no aggregation or activation on Zr-16Nb-xTi. Overall, Ti addition has obvious effects on the developed Zr-16Nb-xTi alloys, and Zr-16Nb-4Ti exhibited low magnetic susceptibility, low modulus, good biocompatibility and proper corrosion properties, demonstrating the potential of use as implant biomaterials.

Diosmetin enhances the sensitivity of radiotherapy by suppressing homologous recombination in endometrial cancer

Radiotherapy is an essential treatment for endometrial cancer (EC), especially in advanced, metastatic, and recurrent cases. Combining radiotherapy, which mainly causes DNA double-strand breaks (DSBs), with small molecules targeting aberrantly activated homologous recombination (HR) repair pathways holds great potential for treating ECs in advanced stages. Here, we demonstrate that diosmetin (DIO), a natural flavonoid, suppresses HR, therefore inhibiting cell proliferation and enhancing the sensitivity of EC to radiotherapy. Clonogenic experiments revealed that combining DIO and X-ray significantly inhibited the viability of EC cells compared to cells treated with diosmetin or X-ray alone. The survival fraction of EC cells decreased to 40% when combining 0.4 Gy X-ray and 4 μM DIO; however, each treatment alone only caused death in approximately 15% and 22% of cancer cells, respectively. Further mechanistic studies showed that diosmetin inhibited the recruitment of RPA2 and RAD51, two critical factors involved in the HR repair pathway, upon the occurrence of DSBs. Thus, we propose that a combination of diosmetin and irradiation is a promising therapeutic strategy for treating endometrial cancer.

Efficacy and immunogenicity of a live L. acidophilus expressing SAD epitope of transmissible gastroenteritis virus as an oral vaccine

Transmissible gastroenteritis virus (TGEV) causes great economic loss to swine industry worldwide. Vaccination is an important method to control the TGEV infection. In this study, a TGEV oral vaccine was generated by transferring a eukaryotic expression recombinant plasmid carrying the SAD (A and D antigenic sites of the S protein) epitope of TGEV into a swine-origin Lactobacillus acidophilus (L. acidophilus). In orally immunized BALB/c mice, the TGEV L. acidophilus oral vaccine induced significantly higher level of SIgA antibodies specific to TGEV compared with the mice immunized with a commercial inactivated TGEV vaccine and similar levels of IgG specific to TGEV as the inactivated vaccine. Furthermore, the TGEV L. acidophilus oral vaccine induced higher levels of IFN-γ, which suggested that the vaccine was able to induce immune response. In brief, this novel TGEV L. acidophilus oral vaccine could induce high levels of both mucosal and humoral immune responses, which has a potential to be used in the pig industries in the future. Keywords: transmissible gastroenteritis virus (TGEV); live L. acidophilus oral vaccine; SIgA antibody; IgG antibody; IFN-γ; IL-4.

[Prevalence of silicosis among Xiangyu railway construction workers in Nanchong from 2008-2007]

Objective: To analyze the prevalence of silicosis in the militias with contribution to the former Xiangyu Railway construction in Nanchong, China, from 2008 to 2017, and to provide a scientific basis for the future development of pneumoconiosis prevention and control strategies based on the current status. Methods: A database was established for the data of 11863 militias with contribution to the former Xiangyu Railway construction in Nanchong, China, who attended our hospital from 2008 to 2017, including 11485 males (96.81%) and 378 females (3.19%). The SPSS 17.0 software was used to analyze the differences in the detection rate of silicosis between militias with different sexes or those with different job types, as well as the age, length of service, and regional distribution of patients. Results: Of the 11863 railway militias in Nanchong, 3169 (26.71%) were diagnosed with silicosis, including 2761 (87.12%) in stage I, 359 (11.33%) in stage II, and 49 (1.55%) in stage III; the males had a significantly higher detection rate of silicosis than the females (χ(2)=64.496, P<0.05); there was a significant difference in the detection rate of silicosis between the militias with different job types (χ(2)=856.839, P<0.05). There were significant differences in the mean age of diagnosis and the mean length of service between the patients with different stages of silicosis (F=4.944, P<0.05; F=3.174, P<0.05). There was a significant difference in the number of militia patients with silicosis between different areas of Nanchong (χ(2)=843.330, P<0.05). Conclusion: The prevalence of silicosis is relatively high among the militias with contribution to the former Xiangyu Railway. It is necessary to strengthen the occupational health monitoring of patients, actively treat and prevent complications, and improve the quality of life of patients.

[Effects of chronic intermittent hypoxia on hepatic function and protective mechanism of adiponectin in rats]

Objective: To explore the effect of chronic intermittent hypoxia (CIH) on rats hepatic function, and the protective mechanism of adiponectin (Ad). Methods: Sixty healthy male wistar rats were randomly divided into 4 groups: normal control (NC), NC+ Ad, CIH, and CIH+ Ad groups with 15 rats in each. The rats in CIH and CIH+ Ad groups were exposed to an intermittent hypoxic chamber 8 hours per day for 4 months. Meanwhile, the rats in both the NC and NC + Ad groups were housed with normal pressure air. The rats in the NC+ Ad and CIH+ Ad groups were additionally treated with an intravenous injection of Ad (10 μg), twice a week for 4 months. At the end of experiment, comparison among groups was made about plasma levels of aspartate amino transferase (AST), alanine amino transferase (ALT), degrees of endoplasmic reticulum stress (ERS) and mitochondrium associated cellular apoptosis. Results: No significant difference was detected in all items between NC and NC+ Ad groups (all P>0.05). Plasma hepatic enzyme levels of AST and ALT were significantly higher in CIH group [(319±21) and (113±9) U/L] than those in NC group [(178±19) and (51±9) U/L] and NC+ Ad group [(175±16) and (52±8) U/L] (all P<0.05). Compared NC with NC+ Ad group, there was more remarkable ERS and mitochondrial injury associated cellular apoptosis in hepatic tissues of CIH group. Such pathological changes were less obvious in CIH+ Ad group than in CIH group (all P<0.05). Conclusion: CIH can induce hepatic injury in rats, while Ad supplement may play a protective role possibly through inhibition of ERS and associated pathways of cellular apoptosis.

H9N2 influenza virus isolated from minks has enhanced virulence in mice

H9N2 is one of the major subtypes of influenza virus circulating in poultry in China, which has a wide host range from bird to mammals. Two H9N2 viruses were isolated from one mink farm in 2014. Phylogenetic analysis showed that internal genes of the H9N2 viruses have close relationship with those of H7N9 viruses. Interestingly, two H9N2 were separated in phylogenetic trees, indicating that they are introduced to this mink farm in two independent events. And further mice studies showed that one H9N2 caused obvious weight loss and 20% mortality in infected mice, while another virus did not cause any clinical sign in mice infected at the same dose. Genetic analysis indicated that the virulent H9N2 contain a natural mutation at 701N in PB2 protein, which was reported to contribute to mammalian adaptation. However, such substitution is absent in the H9N2 avirulent to mice. Circulation of H9N2 in mink may drive the virus to adapt mammals; continual surveillance of influenza virus in mink was warranted.

Aggravation of spinal cord compromise following new osteoporotic vertebral compression fracture prevented by teriparatide in patients with surgical contraindications

Patients with spinal cord deficits following new unstable osteoporotic compression fracture and surgical contraindications were considered to receive conservative treatment. Teriparatide was better than alendronate at improving bone mineral density and bone turnover parameters, as well as preventing aggravation of spinal cord compromise.

INTRODUCTION

This study compared the preventive effects of teriparatide and alendronate on aggravation of spinal cord compromise following new unstable osteoporotic vertebral compression fracture (OVCF) in patients with surgical contraindications.

METHODS

This was a 12-month, randomized, open-label study of teriparatide versus alendronate in 49 patients with new unstable OVCF and surgical contraindications. Neurological function was evaluated using modified Japanese Orthopedic Association (mJOA) score (11-point scale, the maximum score of 11 implies normalcy). Visual analog scale (VAS) scores, kyphotic angles, anterior-border heights and diameters of the spinal canal of the fractured vertebrae, any incident of new OVCFs (onset of OVCF during follow-up), spine bone mineral density (BMD), and serum markers of bone resorption and bone formation were also examined at baseline and 1, 3, 6, and 12 months after initiation of the medication regimen.

RESULTS

At 12 months, mean mJOA score had improved in the teriparatide group and decreased in the alendronate group. Mean concentrations of bone formation and bone resorption biomarkers, mean spine BMD, and mean anterior-border height and spinal canal diameter of the fractured vertebrae were significantly greater in the teriparatide group than in the alendronate group. Mean VAS score, mean kyphotic angle of the fractured vertebrae, and incidence of new OVCFs were significantly smaller in the teriparatide group than in the alendronate group.

CONCLUSIONS

In patients with neurological deficits following new unstable OVCF and with surgical contraindications, teriparatide was better than alendronate at improving the BMD and the bone turnover parameters, as well as preventing aggravation of spinal cord compromise.

Different states of synaptotagmin regulate evoked versus spontaneous release

The tandem C2-domains of synaptotagmin 1 (syt) function as Ca²⁺-binding modules that trigger exocytosis; in the absence of Ca²⁺, syt inhibits spontaneous release. Here, we used proline linkers to constrain and alter the relative orientation of these C2-domains. Short poly-proline helices have a period of three, so large changes in the relative disposition of the C2-domains result from changing the length of the poly-proline linker by a single residue. The length of the linker was varied one residue at a time, revealing a periodicity of three for the ability of the linker mutants to interact with anionic phospholipids and drive evoked synaptic transmission; syt efficiently drove exocytosis when its tandem C2-domains pointed in the same direction. Analysis of spontaneous release revealed a reciprocal relationship between the activation and clamping activities of the linker mutants. Hence, different structural states of syt underlie the control of distinct forms of synaptic transmission.

Synaptotagmin contains tandem Ca²⁺-binding C2-domains that interact with target membranes to trigger exocytosis. Here, Bai et al. manipulate the relative orientation of these two domains using a synthetic polyproline linker and show that a parallel orientation is most effective for membrane interaction and exocytosis.

Role of mitophagy regulated by Parkin/DJ-1 in remote ischemic postconditioning-induced mitigation of focal cerebral ischemia-reperfusion

OBJECTIVE

We evaluated the role of mitophagy controlled by Parkin/DJ-1 in remote ischemic post conditioning-induced mitigation of focal cerebral ischemia-reperfusion (I/R) injury in rats.

MATERIALS AND METHODS

Ninety adult male rats were randomly assigned into 5 groups including a sham operation group (S) and ischemia-reperfusion group (I/R). Focal cerebral I/R was induced by right middle cerebral artery occlusion (MCAO). I/R+remote ischemic postconditioning (I/R+RIPoC), I/R+RIPoC+ mitophagy inhibitor Mdivi-1 (I/R+RIPoC+M), and I/R+RIPoC+ normal saline (I/R+RIPoC+NS) groups all received 3 cycles of 10 minutes reperfusion followed by 10 minutes ischemia in bilateral femoral arteries at the beginning of cerebral reperfusion. I/R+RIPoC+M received mitochondrial division inhibitor (Mdivi-1) before ischemia and after 24h of reperfusion, neurological deficit scores (NDSs) were measured and rats were then sacrificed. Brain was removed and size of the infarct was determined. Apoptosis index and LC3-II/I ratio, Parkin/DJ-1 proteins expression, SOD activity, MDA and 15-F2t-Isoprostane content in cerebral ischemic penumbra were studied. Linear correlation between Parkin/DJ-1 proteins expression and LC3-II/I ratio and cerebral infarct size were analyzed.

RESULTS

In experimental groups the NDSs, percentage of cerebral infarct size, apoptosis index, LC3-II/I ratio, MDA and 15-F2t-Isoprostane content significantly increased and Parkin/DJ-1 proteins were up-regulated (p<0.05). In I/R+RIPoC and I/R+RIPoC+NS groups, NDSs, percentage of cerebral infarct size, apoptosis index, MDA and 15-F2t-Isoprostane content decreased significantly while LC3-II/I ratio and SOD activity increased compared to I/R group. Parkin/DJ-1 proteins were up-regulated in I/R+RIPoC, I/R+RIPoC+NS and I/R+RIPoC+M groups (p<0.05). LC3-II/I ratio and SOD activity significantly decreased (p<0.05). Parkin/DJ-1 proteins expression didn't changed in I/R+RIPoC+M group (p>0.05). The Parkin/DJ-1 proteins expression were positively correlated with LC3-II/I ratio, and negatively correlated with cerebral infarct size (p<0.05).

CONCLUSIONS

Remote Ischemic Post Conditioning (RIPoC) promoted the mitophagy via up-regulation of Parkin/DJ-1 proteins expression and inhibiting the oxidative stress responses, thus mitigating focal cerebral I/R injury in rats.

Development of novel microsatellite markers in the Korean rockfish Sebastes schlegeli

The Korean rockfish Sebastes schlegeli is a valuable recreational and commercial fish in China, and is cultured in land-based tanks and net cages. Fifteen microsatellite markers were developed for this species, and their polymorphisms were examined in a population. The allele number of the 15 markers ranged from 2 to 13, with an average of 5.933 per locus. The observed and expected heterozygosity values ranged from 0.063 to 0.938 (averaging 0.585), and 0.062 to 0.908 (averaging 0.642), respectively. Thirteen loci were at Hardy-Weinberg equilibrium (HWE), whereas the other two significantly deviated from the HWE after a Bonferroni's correction. No significant linkage disequilibrium was detected between the comparisons of these loci. These markers are useful for studies of population genetics, linkage mapping, and other relevant studies on S. schlegeli.

Linker mutations reveal the complexity of synaptotagmin 1 action during synaptic transmission

The Ca(2+) sensor for rapid synaptic vesicle exocytosis, synaptotagmin 1 (syt), is largely composed of two Ca(2+)-sensing C2 domains, C2A and C2B. We investigated the apparent synergy between the tandem C2 domains by altering the length and rigidity of the linker that connects them. The behavior of the linker mutants revealed a correlation between the ability of the C2 domains to penetrate membranes in response to Ca(2+) and to drive evoked neurotransmitter release in cultured mouse neurons, uncovering a step in excitation-secretion coupling. Using atomic force microscopy, we found that the synergy between these C2 domains involved intra-molecular interactions between them. Thus, syt function is markedly affected by changes in the physical nature of the linker that connects its tandem C2 domains. Moreover, the linker mutations uncoupled syt-mediated regulation of evoked and spontaneous release, revealing that syt also acts as a fusion clamp before the Ca(2+) trigger.

Mutations that disrupt Ca²⁺-binding activity endow Doc2β with novel functional properties during synaptic transmission

Double C2-domain protein (Doc2) is a Ca(2+)-binding protein implicated in asynchronous and spontaneous neurotransmitter release. Here we demonstrate that each of its C2 domains senses Ca(2+); moreover, the tethered tandem C2 domains display properties distinct from the isolated domains. We confirm that overexpression of a mutant form of Doc2β, in which two acidic Ca(2+) ligands in the C2A domain and two in the C2B domain have been neutralized, results in markedly enhanced asynchronous release in synaptotagmin 1-knockout neurons. Unlike wild-type (wt) Doc2β, which translocates to the plasma membrane in response to increases in [Ca(2+)](i), the quadruple Ca(2+)-ligand mutant does not bind Ca(2+) but is constitutively associated with the plasma membrane; this effect is due to substitution of Ca(2+) ligands in the C2A domain. When overexpressed in wt neurons, Doc2β affects only asynchronous release; in contrast, Doc2β Ca(2+)-ligand mutants that constitutively localize to the plasma membrane enhance both the fast and slow components of synaptic transmission by increasing the readily releasable vesicle pool size; these mutants also increase the frequency of spontaneous release events. Thus, mutations in the C2A domain of Doc2β that were intended to disrupt Ca(2+) binding result in an anomalous enhancement of constitutive membrane-binding activity and endow Doc2β with novel functional properties.

Resistance of transgenic silkworm to BmNPV could be improved by silencing ie-1 and lef-1 genes

RNA interference (RNAi)-mediated viral inhibition has been used in several organisms for improving viral resistance. In the present study, we reported the use of transgenic RNAi in preventing Bombyx mori nucleopolyhedrovirus (BmNPV) multiplication in the transgenic silkworm B. mori. We targeted the BmNPV immediate-early-1 (ie-1) and late expression factor-1 (lef-1) genes in the transiently transfected BmN cells, in the stable transformed BmN cell line and in the transgenic silkworms. We generated four piggyBac-based vectors containing short double-stranded ie-1 RNA (sdsie-1), short double-stranded lef-1 RNA (sdslef-1), long double-stranded ie-1 RNA (ldsie-1) and both sdsie-1 and sdslef-1 (sds-ie1-lef1) expression cassettes. Strong viral repression was observed in the transiently transfected cells and in the stable transformed BmN cells transfected with sds-ie-1, sdslef-1, ldsie-1 or sds-ie-lef. The decrease of ie-1 mRNA level in the sds-ie1-lef1 transiently transfected cells was most obvious among the cells transfected with different vectors. The inhibitory effect of viral multiplication was decreased in a viral dose-dependent manner; the infection ratio of transfected cells for sds-ie-1, sdslef-1, ldsie-1 and sds-ie-lef decreased by 18.83%, 13.73%, 6.93% and 30.63%, respectively, compared with control cells 5 days after infection. We generated transgenic silkworms using transgenic vector piggyantiIE-lef1-neo with sds-ie1-lef1 expression cassette; the fourth instar larvae of transgenic silkworms of generation G5 exhibited stronger resistance to BmNPV, the mortalities for the transgenic silkworms and control silkworms were 60% and 100%, respectively, at 11 days after inoculation with BmNPV (10(6) occlusion bodies per ml). These results suggest that double-stranded RNA expression of essential genes of BmNPV is a feasible method for breeding silkworms with a high antiviral capacity.

Accuracy of vessel-encoded pseudocontinuous arterial spin-labeling in identification of feeding arteries in patients with intracranial arteriovenous malformations

BACKGROUND AND PURPOSE

Identifying feeding arteries of intracranial AVMs is very important for preoperative evaluation. DSA remains the reference standard for diagnosis but is invasive. Our aim was to evaluate the diagnostic accuracy of vessel-encoded pseudocontinuous arterial spin-labeling in identifying feeding arteries of intracranial AVMs by using DSA as the criterion standard.

MATERIALS AND METHODS

Eighteen patients with AVMs were examined with vessel-encoded pseudocontinuous arterial spin-labeling and DSA. Three postlabeling delays (postlabeling delay = 1, 1.3, and 1.6 seconds) were applied in 6 patients, and a single postlabeling delay (1 second) was applied in the remainder. Perfusion-weighted images were decoded into individual vascular territories with standard and relative tagging efficiencies, respectively. The supply fraction of each feeding artery to the AVM was calculated. The within-subject ANOVA was applied to compare supply fractions acquired across 3 postlabeling delays. Receiver operating characteristic analysis curves were calculated to evaluate the diagnostic accuracy of vessel-encoded pseudocontinuous arterial spin-labeling for identifying the feeding arteries of AVMs.

RESULTS

There were no significant differences in supply fractions of the 3 major arteries to AVMs acquired with 3 postlabeling delays (P > .05). For vessel-encoded pseudocontinuous arterial spin-labeling with standard labeling efficiencies, the area under the receiver operating characteristic analysis curve was 0.942. The optimal cutoff of the supply fraction for identifying feeding arteries was 15.17%, and the resulting sensitivity and specificity were 84.62% and 93.33%, respectively. For vessel-encoded pseudocontinuous arterial spin-labeling with relative labeling efficiencies, the area under the receiver operating characteristic analysis curve was 0.957. The optimal cutoff of the supply fraction was 11.73%, which yielded an 89.74% sensitivity and 93.33% specificity.

CONCLUSIONS

The contribution fraction of each feeding artery of the AVM can be reliably estimated by using vessel-encoded pseudocontinuous arterial spin-labeling. Vessel-encoded pseudocontinuous arterial spin-labeling with either standard or relative labeling efficiencies offers a high level of diagnostic accuracy compared with DSA for identifying feeding arteries.

The crosstalks between adipokines and catecholamines

Adipocytes, which secrete a spectrum of adipokines, play an integral role in metabolism via communications with other endocrine cells. In the present work, we have studied the interplays between adipokines and catecholamines, using 3T3-L1 adipocytes and PC12 cells as the cell models and an integrative experimental platform. We demonstrate that all catecholamines inhibit vesicle trafficking and secretion of leptin and resistin through β-adrenergic receptors, while leptin and resistin enhance the vesicle trafficking and secretion of catecholamines through PKC, PKA, MAPK kinase and Ca(2+) dependent pathways. The crosstalks between adipokines and catecholamines were further corroborated by co-culturing 3T3-L1 adipocytes and PC12 cells. Our findings highlight the importance of adipo-adrenal axis in energy metabolism and the intricate interactions between metabolic hormones.

Roles of cholesterol in vesicle fusion and motion

Although it is well established that exocytosis of neurotransmitters and hormones is highly regulated by numerous secretory proteins, such as SNARE proteins, there is an increasing appreciation of the importance of the chemophysical properties and organization of membrane lipids to various aspects of the exocytotic program. Based on amperometric recordings by carbon fiber microelectrodes, we show that deprivation of membrane cholesterol by methyl-beta-cyclodextrin not only inhibited the extent of membrane depolarization-induced exocytosis, it also adversely affected the kinetics and quantal size of vesicle fusion in neuroendocrine PC12 cells. In addition, total internal fluorescence microscopy studies revealed that cholesterol depletion impaired vesicle docking and trafficking, which are believed to correlate with the dynamics of exocytosis. Furthermore, we found that free cholesterol is able to directly trigger vesicle fusion, albeit with less potency and slower kinetics as compared to membrane depolarization stimulation. These results underscore the versatile roles of cholesterol in facilitating exocytosis.

PKC epsilon facilitates recovery of exocytosis after an exhausting stimulation

It has been well documented that protein kinase Cs (PKCs) play multifaceted roles in regulating exocytosis of neurotransmitters and hormones. But the isoform-specific PKC effects are still poorly elucidated mainly because of the large variety of PKC isoforms and the dubious specificity of the commonly used pharmacological agents. In the present study, based on overexpression of wild-type or dominant negative PKC epsilon, we demonstrate in neuroendocrine PC12 cells that PKC epsilon, but not PKC alpha, facilitates recovery of exocytosis after an exhausting stimulation. Specifically, PKC epsilon mediates fast recovery of the extent of exocytosis in a phosphatidylinositol biphosphate-dependent manner, likely through enhancing the rate of vesicle delivery and reorganization of cortical actin network. In addition, PKC epsilon promotes fast recovery of vesicle release kinetics that is slowed after a strong stimulation. These experimental results may suggest a PKC-dependent mechanism relevant to the short-term plasticity of exocytosis in both neurons and neuroendocrine cells.

Label-free detection of ATP release from living astrocytes with high temporal resolution using carbon nanotube network

Owing to its unique combination of electrical, physiochemical, and one-dimension structural properties, single-walled carbon nanotube (SWNT) has recently emerged as a novel nanoelectronic biosensor for biomolecular detection with extraordinary sensitivity and simple detection scheme. All the realizations so far, however, are limited to static in vitro measurement. Dynamic detection of biomolecule release from living cells which may occur in millisecond timescale has yet to be demonstrated. In the present work, SWNT network was utilized to directly interface with living neuroglial astrocytes and label-freely detect the triggered release of adenosine triphosphate (ATP) from these cells with high temporal resolution. The secreted ATP molecules diffuse into the narrow interface gap between the SWNT-net and the astrocyte, and interact with the nanotubes. Highly charged ATP molecules electrostatically modulate the SWNT conductance leading to measurable current response. This technique provides a novel platform to study ATP release and signaling which play important roles in astrocyte-neuron crosstalk and other essential cellular functions.

Effects of phorbol ester on vesicle dynamics as revealed by total internal reflection fluorescence microscopy

Exocytosis of neurotransmitter or hormone-filled vesicles is a highly dynamic process regulated by various proteins and lipids. As mainly revealed indirectly by the electrophysiological methods, exocytosis is believed to involve multiple kinetic steps in which vesicles transit from one state to another. Using total internal reflection fluorescence microscopy which enables direct visualization of individual vesicles, we developed an analytical framework to track and analyze vesicle dynamics. We demonstrated that all subplasmalemmal vesicles generally undergo constant and caged Brownian motion. And they can be classified into three populations that differ in their motion characteristics and fusion competence. Furthermore, we showed that these vesicle pools are differentially modulated by phorbol-12-myristate-13-acetate, a phorbol ester analog to endogenous diacylglycerol, through both protein-kinase-C-dependent and -independent pathways.

Highly sensitive and selective method to detect dopamine in the presence of ascorbic acid by a new polymeric composite film

A new approach was applied to modify gold electrode with a unique polymer composite for selectively detecting dopamine (DA), a neurotransmitter, in the presence of an electroactive species of ascorbic acid (AA). After self-assembly of 11-mercaptoundecanoic acid (MUA) monolayer on gold surface, polyethylene glycol (PEG) was used to perform electrochemical esterification with MUA. In general, AA is the main interference of DA detection in a biological system. The resulting composite layer showed high sensitivity to detect DA but selectively blocked the interference from AA. Furthermore, for the first time, an interesting mechanism was demonstrated from our experimental results, namely, that the catalytic effect of AA on DA is limited by DA concentration when AA/DA>1. The modified electrode showed good reproducibility (+/-2% relative standard deviation), a low detection limit (10 nM), a fast response time (<2s), high sensitivity (86 nA/microM), a wide dynamic range of detection (20 microM), and great selectivity (without AA interference). The discovery is very promising for applications of detection of DA in a physiological environment where a high concentration of AA always exists.

Chronic daily administration of ethyl docosahexaenoate protects against gerbil brain ischemic damage through reduction of arachidonic acid liberation and accumulation

Recently, we reported that dietary ethyl docosahexaenoate (Et-DHA) intake decreases the level of membrane arachidonic acid (AA), which reduces the generation of AA metabolites in ischemic gerbil brain. As an extended study, we further investigated the influence of the chronic administration of Et-DHA on free AA levels after ischemia. In addition, Na,K-ATPase activity, cation content, cerebral edema and brain damage were also evaluated. Weanling male gerbils were orally pretreated with either Et-DHA (200 mg/kg) or vehicle, once a day for 10 weeks, and subjected to transient forebrain ischemia by bilateral common carotid occlusion for 30 min. Time-course analyses revealed that pretreatment with Et-DHA, compared with pretreatment with the vehicle, significantly decreased the brain's free AA levels during ischemia (5, 15 and 30 min) and after reperfusion (5, 10, 15 and 30 min), and attenuated the decline of Na,K-ATPase activity at examined time points. Pretreatment with Et-DHA significantly prevented an increase in Na(+) concentration and a decrease in K(+) concentration after 24 h of reperfusion, which resulted in lower cerebral water content. Reduced brain infarct volume and low animal mortality were also observed in Et-DHA-treated animals. These data suggest that the reduction of ischemia-induced AA liberation and accumulation by Et-DHA pretreatment may be attributable to (a) protection against the decline of Na,K-ATPase activity, (b) postischemic cerebral edema and brain damage and (c) animal mortality.

Chronic administration of ethyl docosahexaenoate reduces gerbil brain eicosanoid productions following ischemia and reperfusion

Arachidonic acid (AA) and its vasoactive metabolites have been implicated in the pathogenesis of brain damage induced by cerebral ischemia. The membrane AA concentrations can be reduced by changes in dietary fatty acid intake. The purpose of the present study was to investigate the effects of chronic ethyl docosahexaenoate (E-DHA) administration on the generation of eicosanoids of AA metabolism during the period of reperfusion after ischemia in gerbils. Weanling male gerbils were orally pretreated with either E-DHA (100, 200 mg/kg) or vehicle, once a day, for 10 weeks, and subjected to transient forebrain ischemia by bilateral common carotid occlusion for 10 min. E-DHA (200 mg/kg) pretreatment significantly decreased the content of brain lipid AA at the termination of treatment, prevented postischemic impaired regional cerebral blood flow (rCBF) and reduced the levels of brain prostaglandin (PG) PGF(2alpha) and 6-keto-PGF(1alpha), and thromboxane B(2) (TXB(2)), as well as leukotriene (LT) LTB(4) and LTC(4) at 30 and 60 min of reperfusion compared with the vehicle, which was well associated with the attenuated cerebral edema in the E-DHA-treated brain after 48 h of reperfusion. These data suggest that the E-DHA (200 mg/kg) pretreatment reduces the postischemic eicosanoid productions, which may be due to its reduction of the brain lipid AA content.

MR evaluation of the glomerular homing of magnetically labeled mesenchymal stem cells in a rat model of nephropathy

PURPOSE

To assess renal glomerular homing of intravenously injected superparamagnetic iron oxide (SPIO)-labeled mesenchymal stem cells (MSCs) at in vivo and ex vivo magnetic resonance (MR) imaging in an experimental rat model of mesangiolysis.

MATERIALS AND METHODS

Animal procedures were performed in accordance with protocols approved by Institutional Animal Care and Use Committee. Fourteen rats were divided into two groups: one pathologic (n = 10), with persistent mesangiolysis following simultaneous injection of OX-7 monoclonal antibody and puromycin aminonucleoside in which 10(7) SPIO- and DiI-labeled MSCs were injected, and one control (n = 4). In vivo and ex vivo MR imaging examinations were performed with 4.7- and 9.4-T spectrometers, respectively, and T2*-weighted sequences. In vivo signal intensity variations were measured in the liver and kidney before and 6 days after MSC injection. Intrarenal signal intensity variations were correlated with histopathologic data by means of colocalization of DiI fluorescence, alpha-actin, and Prussian blue stain-positive cells. Histologic differences between the glomerular homing of MSCs in different kidney portions were correlated to the areas of MR signal intensity decrease with nonparametric statistical tests.

RESULTS

On in vivo images, signal intensity measurements of pathologic kidneys following MSC injection did not show any signal intensity decrease (P = .7), whereas a 34% +/- 14 (mean +/- standard deviation) signal intensity decrease was observed in the liver (P < .01), where a substantial number of labeled cells were trapped. On ex vivo images, pathologic kidneys showed focal cortical (glomerular) areas of signal intensity loss, which was absent in controls. The areas of low signal intensity correlated well with alpha-actin and Prussian blue stain- and DiI-positive areas (P < .01), which indicates that MSCs specifically home to injured tissue. No MSCs were detected in the kidneys of control animals.

CONCLUSION

Intravenously injected MSCs specifically home to focal areas of glomerular damage and can be detected at ex vivo MR imaging.

Chronic administration of ethyl docosahexaenoate decreases mortality and cerebral edema in ischemic gerbils

Dietary docosahexaenoic acid (DHA) intake can decrease the level of membrane arachidonic acid (AA), which is liberated during cerebral ischemia and implicated in the pathogenesis of brain damage. Therefore, in the present study, we investigated the effects of chronic ethyl docosahexaenoate (E-DHA) administration on mortality and cerebral edema induced by transient forebrain ischemia in gerbils. Male Mongolian gerbils were orally pretreated with either E-DHA (100, 150 mg/kg) or vehicle, once a day, for 4 weeks and were subjected to transient forebrain ischemia by bilateral common carotid occlusion for 30 min. The content of brain lipid AA at the termination of treatment, the survival ratio, change of regional cerebral blood flow (rCBF), brain free AA level, thromboxane B(2) (TXB(2)) production and cerebral edema formation following ischemia and reperfusion were evaluated. E-DHA (150 mg/kg) pretreatment significantly increased survival ratio, prevented post-ischemic hypoperfusion and attenuated cerebral edema after reperfusion compared with vehicle, which was well associated with the reduced levels of AA and TXB(2) in the E-DHA treated brain. These data suggest that the effects of E-DHA pretreatment on ischemic mortality and cerebral edema could be due to reduction of free AA liberation and accumulation, and its metabolite synthesis after ischemia and reperfusion by decreasing the content of membrane AA.

Effects of docosahexaenoic acid on the survival and neurite outgrowth of rat cortical neurons in primary cultures

Effects of docosahexaenoic acid (DHA) on survival and neurite outgrowth were investigated in primary cultures of rat cortical neurons. Cell cultures were prepared from cortex on embryonic day 18 (E-18) for treatment with a series of DHA concentrations (12.5, 25, 50, 75, 100 and 200 microM). Docosahexaenoic acid (25-50 microM) significantly enhanced neuronal viability, but lower concentration of DHA (12.5 microM) did not show an obvious effect. In contrast, higher concentrations of DHA (100-200 microM) exerted the significant opposite effects by decreasing neuronal viability. Furthermore, treatment with 25 microM DHA significantly prevented the neurons from death after different culture days in vitro (DIV). Moreover, measurements from the cultures exposed to 25 microM DHA immediately after plating showed significant increases in the percentage of cells with neurites, the mean number of neurite branches, the total neuritic length per cell and the length of the longest neurite in each cell after 24 and 48 h in vitro (HIV). The DHA-treated neurons had greater growth-associated protein-43 (GAP-43) immunoactivity and higher phosphatidylserine (PS) and phosphatidylethanolamine (PE) contents, but lower phosphatidylcholine (PC) content than control neurons. The significant increased DHA contents were also observed in both PE and PS in the treated neurons. These findings suggest that optimal DHA (25 microM) may have positive effects on the survival and the neurite outgrowth of the cultured fetal rat cortical neurons, and the effects probably are related to DHA-stimulating neuron-specific protein synthesis and its enhancing the discrete phospholipid (PL) content through enrichment of DHA in the PL species.

Computer simulation of the distribution of aluminum speciation in soil solutions in equilibrium with the mineral phase imogolite

The speciation of aluminum (Al) is a critical issue when evaluating the environmental and biological significance of elevated Al concentrations in soil solutions caused by acidic precipitation. Numerous studies have revealed that, with increased concentrations of silica acid in soil, the activity of Al species in soil solutions is greatly modified by SiO(4)(2-). However, thus far there has been little thorough theoretical modeling of this subject. This paper reports a computer simulation of the distribution of Al speciation in soil solutions in equilibrium with the mineral phase imogolite based on a chemical equilibrium calculation. The unique characteristic associated with imogolite reported by previous researchers can be explained theoretically by the proposed model. The dissolved silica has a remarkable influence on Al speciation: increasing concentrations of silica acid may effectively inhibit the formation of polymeric alumino-hydroxo species, and, furthermore, detoxify Al toxicity to plants.

Rapid three-dimensional diffusion MRI facilitates the study of acute stroke in mice

MRI studies using mouse brain models of ischemia are becoming a valuable tool for understanding the mechanism of stroke, since transgenic models are now available. However, the small size of the mouse brain and the surgical complexity of creating ischemia in mice make it technically challenging to obtain high-quality MRI data. Therefore, there are few reports of MRI studies in murine cerebral ischemia. In this project a newly developed rapid 3D diffusion-weighted imaging (DWI) technique was applied to study experimental stroke in a mouse model of reversible middle cerebral artery occlusion (MCAO). Ischemic volumes were successfully delineated using this 3D whole-brain imaging technique with high spatial (0.34 x 0.5 x 1.0 mm(3) before zero-filling) and temporal (7 min) resolution. The 3D observation revealed the characteristic evolution of stroke after transient MCAO. There was a temporarily high diffusion constant in the cortex during early reperfusion, followed by a secondary energy failure in the cortex and caudate-putamen at 6 and 21 h of reperfusion. Magn Reson Med 46:183-188, 2001.

[Analysis and expression of Hyphantria cunea nuclear polyhedrosis virus sod gene]

The sequencing results indicated that Hyphantria cunea nuclear polyhedrosis virus (HcNPV) sod gene open reading frame of 456 nt encoding protein of 151 amino acid, was identified to that of Bombyx mori nuclear polyhedrosis virus (BmNPV), and exhibited 97.2% homology at nucletde level to that of Autographa californica nuclear polyhedrosis virus (AcNPV), three amino acid residues difference in amino acid level with AcNPV sod. The essential amino acid residues for the construction and active could be detected in HcNPV sod. Activity of the SOD is 147.09 U per milliliter E. coli.

In vivo three-dimensional reconstruction of rat brain axonal projections by diffusion tensor imaging

The in situ assessment of axonal projections of the brain has been severely limited by the lack of noninvasive techniques to study this type of anatomy. We show here that in vivo three-dimensional (3D) reconstruction of axonal projections can be achieved using a rapid 3D high-resolution diffusion-weighted imaging technique combined with a recently designed fiber reconstruction algorithm. As a first example, neuronal pathways in the rat brain were probed. Eight well-known fiber projections; genu and splenium of corpus callosum, internal and external capsule, fimbria, anterior commissure, optic tract, and stria terminalis were tracked and shown to be in agreement with the location of these known axonal projections. The experiment took 2 hr and shorter times should be possible in the clinical situation. By combining anisotropy information with fiber tracking, the anisotropy of individual projections was also documented. Magn Reson Med 42:1123-1127, 1999.

In vivo three-dimensional reconstruction of rat brain axonal projections by diffusion tensor imaging

The in situ assessment of axonal projections of the brain has been severely limited by the lack of noninvasive techniques to study this type of anatomy. We show here that in vivo three-dimensional (3D) reconstruction of axonal projections can be achieved using a rapid 3D high-resolution diffusion-weighted imaging technique combined with a recently designed fiber reconstruction algorithm. As a first example, neuronal pathways in the rat brain were probed. Eight well-known fiber projections; genu and splenium of corpus callosum, internal and external capsule, fimbria, anterior commissure, optic tract, and stria terminalis were tracked and shown to be in agreement with the location of these known axonal projections. The experiment took 2 hr and shorter times should be possible in the clinical situation. By combining anisotropy information with fiber tracking, the anisotropy of individual projections was also documented. Magn Reson Med 42:1123-1127, 1999.

Delayed reduction of tissue water diffusion after myocardial ischemia

The apparent diffusion coefficient (ADC) of water after regional myocardial ischemia was measured in isolated, perfused rabbit hearts by using magnetic resonance imaging (MRI) techniques. After ligation of the left anterior descending coronary artery, the ADC of the nonperfused region showed a gradual but significant decreasing trend over time, whereas that of the normally perfused myocardium remained constant. Morphological analysis revealed that the ADC decrease reflected the expansion of a subregion of reduced ADC within the nonperfused myocardium. The dynamics of the diffusion change and the morphological progression of the affected tissue suggest that the ADC decrease may be linked to the onset of myocardial infarction, which is known to involve myocyte swelling. The ADC reduction provides a potentially valuable MRI tissue-contrast mechanism for noninvasively determining the viability of the ischemic myocardium and assessing the dynamics of acute myocardial infarction.

Amyloid precursor protein metabolism in primary cell cultures of neurons, astrocytes, and microglia

Amyloid precursor protein (APP) gives rise by proteolytic processing to the amyloid beta peptide (A beta) found abundantly in cerebral senile plaques of individuals with Alzheimer's disease. APP is highly expressed in the brain. To assess the source of cerebral A beta, the metabolism of APP was investigated in the major cell types of the newborn rat cerebral cortex by pulse/chase labeling and immunoprecipitation of the APP and APP metabolic fragments. We describe a novel C-terminally truncated APP isoform that appears to be made only in neurons. The synthesis, degradation, and metabolism of APP were quantified by phosphorimaging in neurons, astrocytes, and microglia. The results show that although little APP is metabolized through the amyloidogenic pathways in each of the three cultures, neurons appear to generate more A beta than astrocytes or microglia.

Soluble amyloid beta-protein is a marker of Alzheimer amyloid in brain but not in cerebrospinal fluid

The amyloid beta protein (A beta), a 4 kD fragment of the beta amyloid precursor protein, is deposited as insoluble amyloid in the brain of Alzheimer disease (AD) subjects. Soluble A beta is a normal metabolic product and is present in cerebrospinal fluid. We identified soluble A beta forms of 4kD, 3kD and 3.7kD in AD but not in control brains free of amyloid deposits. All three forms of soluble A beta extend beyond residue 40. Analysis of cerebrospinal fluid from the same subjects confirmed the presence of only 4kD A beta in comparable amounts in AD and controls. The presence of soluble A beta only in brain regions with amyloid suggests they are related. The undetectability of soluble A beta in control brains indicates that it is normally removed or bound to other proteins. Failure of this protective mechanism might cause amyloid formation in AD.

Fatal familial insomnia, a prion disease with a mutation at codon 178 of the prion protein gene

BACKGROUND

We previously described two members of a family affected by an apparently genetically determined fatal disease characterized clinically by progressive insomnia, dysautonomia, and motor signs and characterized pathologically by severe atrophy of the anterior ventral and mediodorsal thalamic nuclei. Five other family members who died of this disease, which we termed "fatal familial insomnia," had broader neuropathologic changes suggesting that fatal familial insomnia could be a prion disease.

METHODS

We used antibodies to prion protein (PrP) to perform dot and Western blot analyses, with and without proteinase K, on brain tissue obtained at autopsy from two patients with fatal familial insomnia, three patients with sporadic Creutzfeldt-Jakob disease, and six control subjects. The coding region of the PrP gene was amplified and sequenced in the samples from the two patients with fatal familial insomnia. Restriction-enzyme analysis was carried out with amplified PrP DNA from 33 members of the kindred.

RESULTS

Protease-resistant PrP was found in both patients with fatal familial insomnia, but the size and number of protease-resistant fragments differed from those in Creutzfeldt-Jakob disease. In the family with fatal familial insomnia, all 4 affected members and 11 of the 29 unaffected members had a point mutation in PrP codon 178 that results in the substitution of asparagine for aspartic acid and elimination of the Tth111 I restriction site. Linkage analysis showed a close relation between the point mutation and the disease (maximal lod score, 3.4 when theta was zero).

CONCLUSIONS

Fatal familial insomnia is a prion disease with a mutation in codon 178 of the PrP gene, but the disease phenotype seems to differ from that of previously described kindreds with the same point mutation.