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1.
PLoS Pathog ; 19(12): e1011831, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-38091362

RESUMEN

Protein phosphatases are post-translational regulators of Toxoplasma gondii proliferation, tachyzoite-bradyzoite differentiation and pathogenesis. Here, we identify the putative protein phosphatase 6 (TgPP6) subunits of T. gondii and elucidate their role in the parasite lytic cycle. The putative catalytic subunit TgPP6C and regulatory subunit TgPP6R likely form a complex whereas the predicted structural subunit TgPP6S, with low homology to the human PP6 structural subunit, does not coassemble with TgPP6C and TgPP6R. Functional studies showed that TgPP6C and TgPP6R are essential for parasite growth and replication. The ablation of TgPP6C significantly reduced the synchronous division of the parasite's daughter cells during endodyogeny, resulting in disordered rosettes. Moreover, the six conserved motifs of TgPP6C were required for efficient endodyogeny. Phosphoproteomic analysis revealed that ablation of TgPP6C predominately altered the phosphorylation status of proteins involved in the regulation of the parasite cell cycle. Deletion of TgPP6C significantly attenuated the parasite virulence in mice. Immunization of mice with TgPP6C-deficient type I RH strain induced protective immunity against challenge with a lethal dose of RH or PYS tachyzoites and Pru cysts. Taken together, the results show that TgPP6C contributes to the cell division, replication and pathogenicity in T. gondii.


Asunto(s)
Parásitos , Fosfoproteínas Fosfatasas , Toxoplasma , Animales , Humanos , Ratones , Dominio Catalítico , Ciclo Celular/genética , División Celular , Parásitos/metabolismo , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , Toxoplasma/metabolismo , Virulencia/genética , Fosfoproteínas Fosfatasas/genética , Fosfoproteínas Fosfatasas/metabolismo
2.
FASEB J ; 37(6): e22932, 2023 06.
Artículo en Inglés | MEDLINE | ID: mdl-37115746

RESUMEN

Glutaredoxins (Grxs) are ubiquitous antioxidant proteins involved in many molecular processes to protect cells against oxidative damage. Here, we study the roles of Grxs in the pathogenicity of Toxoplasma gondii. We show that Grxs are localized in the mitochondria (Grx1), cytoplasm (Grx2), and apicoplast (Grx3, Grx4), while Grx5 had an undetectable level of expression. We generated Δgrx1-5 mutants of T. gondii type I RH and type II Pru strains using CRISPR-Cas9 system. No significant differences in the infectivity were detected between four Δgrx (grx2-grx5) strains and their respective wild-type (WT) strains in vitro or in vivo. Additionally, no differences were detected in the production of reactive oxygen species, total antioxidant capacity, superoxide dismutase activity, and sensitivity to external oxidative stimuli. Interestingly, RHΔgrx1 or PruΔgrx1 exhibited significant differences in all the investigated aspects compared to the other grx2-grx5 mutant and WT strains. Transcriptome analysis suggests that deletion of grx1 altered the expression of genes involved in transport and metabolic pathways, signal transduction, translation, and obsolete oxidation-reduction process. The data support the conclusion that grx1 supports T. gondii resistance to oxidative killing and is essential for the parasite growth in cultured cells and pathogenicity in mice and that the active site CGFS motif was necessary for Grx1 activity.


Asunto(s)
Antioxidantes , Toxoplasma , Animales , Ratones , Glutarredoxinas/genética , Toxoplasma/genética , Secuencia de Aminoácidos , Virulencia , Oxidación-Reducción , Estrés Oxidativo
3.
Fish Shellfish Immunol ; 150: 109662, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38821229

RESUMEN

SIRT6, a key member of the sirtuin family, plays a pivotal role in regulating a number of vital biological processes, including energy metabolism, oxidative stress, and immune system modulation. Nevertheless, the function of SIRT6 in bony fish, particularly in the context of antiviral immune response, remains largely unexplored. In this study, a sirt6 was cloned and characterized in a commercial fish, the Chinese perch (Siniperca chuatsi). The SIRT6 possesses conserved SIR2 domain with catalytic core region when compared with other vertebrates. Tissue distribution analysis indicated that sirt6 was expressed in all detected tissues, and the sirt6 was significantly induced following infection of infectious haemorrhagic syndrome virus (IHSV). The overexpression of SIRT6 resulted in significant upregulation of interferon-stimulated genes (ISGs), such as viperin, mx, isg15, irf3 and ifp35, and inhibited viral replication. It was further found that SIRT6 was located in nucleus and could enhance the expression of ISGs induced by type I and II IFNs. These findings may provide new information in relation with the function of SIRT6 in vertebrates, and with viral prevention strategy development in aquaculture.


Asunto(s)
Secuencia de Aminoácidos , Enfermedades de los Peces , Proteínas de Peces , Regulación de la Expresión Génica , Inmunidad Innata , Percas , Filogenia , Infecciones por Rhabdoviridae , Sirtuinas , Animales , Sirtuinas/genética , Sirtuinas/inmunología , Sirtuinas/metabolismo , Enfermedades de los Peces/inmunología , Enfermedades de los Peces/virología , Proteínas de Peces/genética , Proteínas de Peces/inmunología , Proteínas de Peces/química , Inmunidad Innata/genética , Infecciones por Rhabdoviridae/inmunología , Infecciones por Rhabdoviridae/veterinaria , Regulación de la Expresión Génica/inmunología , Percas/inmunología , Alineación de Secuencia/veterinaria , Perfilación de la Expresión Génica/veterinaria
4.
Surg Endosc ; 38(2): 648-658, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38012440

RESUMEN

BACKGROUND: Portal vein system thrombosis (PVST) is a potentially fatal complication after splenectomy with esophagogastric devascularization (SED) in cirrhotic patients with portal hypertension. However, the impact of portal vein velocity (PVV) on PVST after SED remains unclear. Therefore, this study aims to explore this issue. METHODS: Consecutive cirrhotic patients with portal hypertension who underwent SED at Tongji Hospital between January 2010 and June 2022 were enrolled. The patients were divided into two groups based on the presence or absence of PVST, which was assessed using ultrasound or computed tomography after the operation. PVV was measured by duplex Doppler ultrasound within one week before surgery. The independent risk factors for PVST were analyzed using univariate and multivariate logistic regression analysis. A nomogram based on these variables was developed and internally validated using 1000 bootstrap resamples. RESULTS: A total of 562 cirrhotic patients with portal hypertension who underwent SED were included, and PVST occurred in 185 patients (32.9%). Multivariate logistic regression analysis showed that PVV was the strongest independent risk factor for PVST. The incidence of PVST was significantly higher in patients with PVV ≤ 16.5 cm/s than in those with PVV > 16.5 cm/s (76.2% vs. 8.5%, p < 0.0001). The PVV-based nomogram was internally validated and showed good performance (optimism-corrected c-statistic = 0.907). Decision curve and clinical impact curve analyses indicated that the nomogram provided a high clinical benefit. CONCLUSION: A nomogram based on PVV provided an excellent preoperative prediction of PVST after splenectomy with esophagogastric devascularization.


Asunto(s)
Hipertensión Portal , Trombosis de la Vena , Humanos , Vena Porta/patología , Esplenectomía/efectos adversos , Cirrosis Hepática/cirugía , Complicaciones Posoperatorias/diagnóstico por imagen , Complicaciones Posoperatorias/epidemiología , Complicaciones Posoperatorias/etiología , Trombosis de la Vena/diagnóstico por imagen , Trombosis de la Vena/etiología , Hipertensión Portal/cirugía , Hipertensión Portal/complicaciones
5.
Ann Noninvasive Electrocardiol ; 29(1): e13107, 2024 01.
Artículo en Inglés | MEDLINE | ID: mdl-38288514

RESUMEN

OBJECTIVE: Patients treated with preoperative chemotherapy and immunotherapy for bladder cancer may be at increased risk of cardiotoxicity and electrophysiological abnormalities. This study aimed to analyze their electrocardiographic (ECG) alterations. METHODS: Patients with bladder cancer who were hospitalized and receiving tislelizumab plus nab-paclitaxel (TnP) were enrolled prospectively. ECG, cardiac biomarkers, and echocardiography were performed at baseline and the end of TnP. RESULTS: A total of 60 patients (76.7% males), including 30 muscle-invasive and 30 non-muscle-invasive bladder cancer, received three or four cycles of TnP, respectively. Hypertension was the commonest comorbidity (41.7%), and 25 patients (41.7%) were prescribed cardiovascular drugs. In comparison with baseline characteristics, cardiac troponin I (cTnI) and N-terminal pro-brain natriuretic peptide (NT-proBNP) were within normal ranges after TnP. However, echocardiographic parameter of left ventricular ejection fraction slightly decreased after TnP (62.81 ± 3.81% to 61.10 ± 4.37%, p = .011). The incidence of abnormal ECG increased from 65.0% at baseline to 76.7%, of which only a higher prevalence of fragmented QRS (fQRS) was observed (33.3% to 50.0%, p = .013; mainly in inferior leads). ECG parameters of QT dispersion (QTd) were prolonged significantly after the regimen (39.50 ± 11.37 to 44.20 ± 15.85 ms, p = .019). CONCLUSION: In bladder cancer patients receiving preoperative chemotherapy combined with immunotherapy, the main ECG abnormality was fQRS and QTd, with relatively normal cardiac biomarkers and echocardiographic parameters. Regular ECG screening should be carried out carefully to detect potential cardiotoxicity in the long-term follow-up.


Asunto(s)
Anticuerpos Monoclonales Humanizados , Electrocardiografía , Inmunoterapia , Paclitaxel , Neoplasias de la Vejiga Urinaria , Femenino , Humanos , Masculino , Biomarcadores , Cardiotoxicidad , Inmunoterapia/efectos adversos , Péptido Natriurético Encefálico , Volumen Sistólico , Neoplasias de la Vejiga Urinaria/tratamiento farmacológico , Neoplasias de la Vejiga Urinaria/terapia , Función Ventricular Izquierda , Paclitaxel/uso terapéutico , Antineoplásicos Inmunológicos/uso terapéutico , Anticuerpos Monoclonales Humanizados/uso terapéutico
6.
Ann Surg ; 277(1): e103-e111, 2023 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-35081573

RESUMEN

OBJECTIVE: To compare the short- and long-term outcomes of robot-assisted (RALR), laparoscopic (LLR), or open liver resection (OLR) in the treatment of Barcelona Clinic Liver Cancer (BCLC) stage 0-A hepatocellular carcinoma (HCC). SUMMARY BACKGROUND DATA: Following the Balliol IDEAL classification, long-term oncological outcomes can be used to evaluate the value of minimally invasive techniques in the treatment of HCC, and to assess whether they should become a standard practice. METHODS: Data from prospective cohorts of patients with BCLC stage 0-A HCC who underwent curative liver resection using OLR, LLR, or RALR at Tongji Hospital were reviewed. The short-term and long-term oncological outcomes of these 3 different surgical approaches after adequate follow-up were compared using propensity score matching to reduce selection bias. RESULTS: Of 369 patients included in this study (71, RALR; 141, LLR; and 157, OLR), 56 patients in each of the 3 groups were chosen for further comparison, after propensity score matching. In the minimally invasive group (RALR+LLR), both the operative time and duration of Pringle's maneuver were significantly longer than those in the OLR group; however, the length of hospital stay was significantly shorter. There were no significant differences in the other intraoperative parameters and the incidence of postoperative complications among the 3 groups. HCC recurrence in the minimally invasive group when compared with the OLR group was characterized by a significantly higher proportion of single lesion or early-stage HCC. However, there were no significant differences in the 5-year disease-free survival (63.8%, 54.4%, and 50.6%) or overall survival rates (80.8%, 78.6%, and 75.7%, respectively) among the 3 groups. Clinically significant portal hypertension was the only risk factor that negatively affected the 5-year disease-free survival rate. Multivariate Cox regression analysis showed that clinically significant portal hypertension, serum alpha-fetoprotein level (≥400 ng/mL), and Edmondson-Steiner grading (III+IV) were independent risk factors for poor long-term survival. CONCLUSION: Both robotic and laparoscopic hepatectomies were safe and effective for patients with BCLC stage 0-A HCC when compared with open hepatectomy.


Asunto(s)
Carcinoma Hepatocelular , Hipertensión Portal , Laparoscopía , Neoplasias Hepáticas , Procedimientos Quirúrgicos Robotizados , Humanos , Carcinoma Hepatocelular/cirugía , Hepatectomía/métodos , Hipertensión Portal/etiología , Laparoscopía/métodos , Tiempo de Internación , Neoplasias Hepáticas/cirugía , Complicaciones Posoperatorias/epidemiología , Puntaje de Propensión , Estudios Prospectivos , Estudios Retrospectivos
7.
Cell Mol Life Sci ; 79(12): 599, 2022 Nov 21.
Artículo en Inglés | MEDLINE | ID: mdl-36409355

RESUMEN

BACKGROUND: Parkinson's disease (PD) is characterized by selective and progressive dopamine (DA) neuron loss in the substantia nigra and other brain regions, with the presence of Lewy body formation. Most PD cases are sporadic, whereas monogenic forms of PD have been linked to multiple genes, including Leucine kinase repeat 2 (LRRK2) and PTEN-induced kinase 1 (PINK1), two protein kinase genes involved in multiple signaling pathways. There is increasing evidence to suggest that endogenous DA and DA-dependent neurodegeneration have a pathophysiologic role in sporadic and familial PD. METHODS: We generated patient-derived dopaminergic neurons and human midbrain-like organoids (hMLOs), transgenic (TG) mouse and Drosophila models, expressing both mutant and wild-type (WT) LRRK2 and PINK1. Using these models, we examined the effect of LRRK2 and PINK1 on tyrosine hydroxylase (TH)-DA pathway. RESULTS: We demonstrated that PD-linked LRRK2 mutations were able to modulate TH-DA pathway, resulting in up-regulation of DA early in the disease which subsequently led to neurodegeneration. The LRRK2-induced DA toxicity and degeneration were abrogated by wild-type (WT) PINK1 (but not PINK1 mutations), and early treatment with a clinical-grade drug, α-methyl-L-tyrosine (α-MT), a TH inhibitor, was able to reverse the pathologies in human neurons and TG Drosophila models. We also identified opposing effects between LRRK2 and PINK1 on TH expression, suggesting that functional balance between these two genes may regulate the TH-DA pathway. CONCLUSIONS: Our findings highlight the vital role of the TH-DA pathway in PD pathogenesis. LRRK2 and PINK1 have opposing effects on the TH-DA pathway, and its balance affects DA neuron survival. LRRK2 or PINK1 mutations can disrupt this balance, promoting DA neuron demise. Our findings provide support for potential clinical trials using TH-DA pathway inhibitors in early or prodromic PD.


Asunto(s)
Proteínas de Drosophila , Enfermedad de Parkinson , Ratones , Animales , Humanos , Dopamina/metabolismo , Tirosina 3-Monooxigenasa/genética , Tirosina 3-Monooxigenasa/metabolismo , Enfermedad de Parkinson/metabolismo , Proteína 2 Quinasa Serina-Treonina Rica en Repeticiones de Leucina/genética , Proteína 2 Quinasa Serina-Treonina Rica en Repeticiones de Leucina/metabolismo , Neuronas Dopaminérgicas/metabolismo , Ratones Transgénicos , Drosophila/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo
8.
Hepatobiliary Pancreat Dis Int ; 22(3): 288-293, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-36041970

RESUMEN

BACKGROUND: Pancreaticobiliary maljunction (PBM) is a well-known high-risk factor for biliary malignant tumors because of constant pancreaticobiliary reflux (PBR). However, the impact of occult pancreaticobiliary reflux (OPR), which is characterized by high bile amylase levels in individuals with anatomically normal pancreaticobiliary junction, on biliary diseases remains unclear. The aim of this study was to assess the correlation between OPR and biliary diseases. METHODS: We enrolled 94 consecutive patients with normal pancreaticobiliary junction and primary biliary diseases confirmed by magnetic resonance cholangiopancreatography. We prospectively collected patients' bile samples and measured bile amylase levels. We investigated the incidence of OPR and the difference in bile amylase levels among these patients and assessed the correlation between high bile amylase levels (HBAL) and benign or malignant biliary diseases, as well as the OPR risk factors. RESULTS: The incidence of OPR was 36.6% in patients with benign biliary diseases, 26.7% in those with cholangiocarcinoma and 62.5% in those with gallbladder cancer. The median bile amylase level tended to be higher in patients with gallbladder cancer than in those with benign biliary diseases, but there was no significant difference (165.5 IU/L vs. 23.0 IU/L, P = 0.212). The prevalence of an HBAL with bile amylase levels of 1000-7500 IU/L was similar in patients with gallbladder cancer and benign biliary diseases. However, the incidence of HBAL with bile amylase levels greater than 7500 IU/L was significantly higher in patients with gallbladder cancer than in those with benign biliary diseases (37.5% vs. 4.2%, P = 0.012). Multivariate logistic regression analysis revealed that choledocholithiasis was an independent risk factor for OPR. CONCLUSIONS: OPR can occur in benign and malignant biliary diseases, and it may be a pathogenic factor for some benign biliary diseases and a high-risk factor for gallbladder cancer. There is a correlation between choledocholithiasis and OPR.


Asunto(s)
Sistema Biliar , Carcinoma in Situ , Coledocolitiasis , Enfermedades de la Vesícula Biliar , Neoplasias de la Vesícula Biliar , Humanos , Neoplasias de la Vesícula Biliar/epidemiología , Neoplasias de la Vesícula Biliar/etiología , Neoplasias de la Vesícula Biliar/patología , Amilasas/análisis , Enfermedades de la Vesícula Biliar/diagnóstico por imagen , Enfermedades de la Vesícula Biliar/epidemiología , Sistema Biliar/patología , Conductos Pancreáticos/diagnóstico por imagen
9.
Sensors (Basel) ; 23(23)2023 Nov 23.
Artículo en Inglés | MEDLINE | ID: mdl-38067724

RESUMEN

Carrier phase measurements currently play a crucial role in achieving rapid and highly accurate positioning of global navigation satellite systems (GNSS). Resolving the integer ambiguity correctly is one of the key steps in this process. To address the inefficiency and slow search problem during ambiguity solving, we propose a single-frequency GNSS integer ambiguity solving based on an adaptive genetic particle swarm optimization (AGPSO) algorithm. Initially, we solve for the floating-point solution and its corresponding covariance matrix using the carrier-phase double difference equation. Subsequently, we decorrelate it using the inverse integer Cholesky algorithm. Furthermore, we introduce an improved fitness function to enhance convergence and search performance. Finally, we combine a particle swarm optimization algorithm with adaptive weights to conduct an integer ambiguity search, where each generation selectively undergoes half-random crossover and mutation operations to facilitate escaping local optima. Comparative studies against traditional algorithms and other intelligent algorithms demonstrate that the AGPSO algorithm exhibits faster convergence rates, improved stability in integer ambiguity search results, and in practical experiments the baseline accuracy of the solution is within 0.02 m, which has some application value in the practical situation of short baselines.

10.
Exp Appl Acarol ; 91(3): 439-461, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37870736

RESUMEN

Chiggers are common ectoparasites and the exclusive vector of scrub typhus. Based on previous investigations from a unique geographical area in Yunnan Province of southwest China, the Three Parallel Rivers Area, we retrospectively studied the species diversity and related ecology of chiggers on rodents and other small mammals. A very high species diversity of 120 chigger species was identified. Five dominant chigger species accounted for 59.4% (5238/8965) of total chiggers, and among them Leptotrombidium scutellare is the second major vector of scrub typhus in China. Species diversity of the chigger community fluctuates greatly in different altitudinal and latitudinal gradients. There are significant differences in species composition, species diversity and dominant species of chiggers among hosts with apparent community heterogeneity. Based on the species abundance distribution, the expected total number of chigger species was estimated to be 170, 50 more than the number of actually collected species; this further indicates a very high chigger species diversity in this area. The bipartite ecological network analysis revealed the intricate relationships between chigger and host species-positive and negative correlations existed among some species of dominant and vector chiggers.


Asunto(s)
Infestaciones por Ácaros , Enfermedades de los Roedores , Tifus por Ácaros , Trombiculidae , Animales , Estudios Retrospectivos , China , Mamíferos/parasitología , Infestaciones por Ácaros/parasitología , Roedores/parasitología
11.
Fa Yi Xue Za Zhi ; 39(1): 1-6, 2023 Feb 25.
Artículo en Inglés, Zh | MEDLINE | ID: mdl-37038848

RESUMEN

OBJECTIVES: To analyze the gross pathological data of sudden cardiac death (SCD) with different causes, to provide data support for the identification of sudden cardiac death with unknown causes. METHODS: A total of 167 adult SCD cases in the archive of the Forensic Expertise Institute of Nanjing Medical University from 2010 to 2020 were collected. The gross pathological data of SCD cases were summarized and the characteristics of different causes of death were statistically analyzed. RESULTS: The ratio of male to female SCD cases was 3.4∶1. Coronary heart disease was the leading cause of SCD, and mainly distributed in people over 40 years old. SCD caused by myocarditis was mainly distributed in young people and the mean age of death was (34.00±9.55) years. By analyzing the differences in cardiac pathological parameters of SCD with different causes, it was found that the aortic valve circumference was significantly dilated in the SCD caused by aortic aneurysm or dissection (P<0.05). The heart weight of SCD caused by aortic aneurysm or dissection and combined factors was greater, and both pulmonary and tricuspid valvular rings were dilated in the SCD caused by combined factors in adult males (P<0.05). CONCLUSIONS: Various gross pathological measures of SCD with different causes are different, which has reference value in the cause of death identification of SCD.


Asunto(s)
Enfermedad Coronaria , Muerte Súbita Cardíaca , Humanos , Adulto , Masculino , Femenino , Adolescente , Adulto Joven , Muerte Súbita Cardíaca/etiología , Muerte Súbita Cardíaca/patología , Corazón , Medicina Legal , Autopsia
12.
BMC Neurosci ; 23(1): 3, 2022 01 04.
Artículo en Inglés | MEDLINE | ID: mdl-34983390

RESUMEN

BACKGROUND: Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are common age-related neurodegenerative diseases comprising Lewy body spectrum disorders associated with cortical and subcortical Lewy body pathology. Over 30% of PD patients develop PD dementia (PDD), which describes dementia arising in the context of established idiopathic PD. Furthermore, Lewy bodies frequently accompany the amyloid plaque and neurofibrillary tangle pathology of Alzheimer's disease (AD), where they are observed in the amygdala of approximately 60% of sporadic and familial AD. While PDD and DLB share similar pathological substrates, they differ in the temporal onset of motor and cognitive symptoms; however, protein markers to distinguish them are still lacking. METHODS: Here, we systematically studied a series of AD and PD pathogenesis markers, as well as mitochondria, mitophagy, and neuroinflammation-related indicators, in the substantia nigra (SN), temporal cortex (TC), and caudate and putamen (CP) regions of human post-mortem brain samples from individuals with PDD and DLB and condition-matched controls. RESULTS: We found that p-APPT668 (TC), α-synuclein (CP), and LC3II (CP) are all increased while the tyrosine hydroxylase (TH) (CP) is decreased in both PDD and DLB compared to control. Also, the levels of Aß42 and DD2R, IBA1, and p-LRRK2S935 are all elevated in PDD compared to control. Interestingly, protein levels of p-TauS199/202 in CP and DD2R, DRP1, and VPS35 in TC are all increased in PDD compared to DLB. CONCLUSIONS: Together, our comprehensive and systematic study identified a set of signature proteins that will help to understand the pathology and etiology of PDD and DLB at the molecular level.


Asunto(s)
Enfermedad de Alzheimer , Demencia , Enfermedad por Cuerpos de Lewy , Enfermedad de Parkinson , Enfermedad de Alzheimer/complicaciones , Encéfalo/patología , Demencia/complicaciones , Demencia/patología , Humanos , Enfermedad por Cuerpos de Lewy/complicaciones , Enfermedad por Cuerpos de Lewy/patología , Enfermedad de Parkinson/complicaciones
13.
Nature ; 529(7584): 54-8, 2016 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-26738590

RESUMEN

How black holes accrete surrounding matter is a fundamental yet unsolved question in astrophysics. It is generally believed that matter is absorbed into black holes via accretion disks, the state of which depends primarily on the mass-accretion rate. When this rate approaches the critical rate (the Eddington limit), thermal instability is supposed to occur in the inner disk, causing repetitive patterns of large-amplitude X-ray variability (oscillations) on timescales of minutes to hours. In fact, such oscillations have been observed only in sources with a high mass-accretion rate, such as GRS 1915+105 (refs 2, 3). These large-amplitude, relatively slow timescale, phenomena are thought to have physical origins distinct from those of X-ray or optical variations with small amplitudes and fast timescales (less than about 10 seconds) often observed in other black-hole binaries-for example, XTE J1118+480 (ref. 4) and GX 339-4 (ref. 5). Here we report an extensive multi-colour optical photometric data set of V404 Cygni, an X-ray transient source containing a black hole of nine solar masses (and a companion star) at a distance of 2.4 kiloparsecs (ref. 8). Our data show that optical oscillations on timescales of 100 seconds to 2.5 hours can occur at mass-accretion rates more than ten times lower than previously thought. This suggests that the accretion rate is not the critical parameter for inducing inner-disk instabilities. Instead, we propose that a long orbital period is a key condition for these large-amplitude oscillations, because the outer part of the large disk in binaries with long orbital periods will have surface densities too low to maintain sustained mass accretion to the inner part of the disk. The lack of sustained accretion--not the actual rate--would then be the critical factor causing large-amplitude oscillations in long-period systems.

14.
New Phytol ; 229(1): 296-307, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-32762047

RESUMEN

The continuing nitrogen (N) deposition observed worldwide alters ecosystem nutrient cycling and ecosystem functioning. Litter decomposition is a key process contributing to these changes, but the numerous mechanisms for altered decomposition remain poorly identified. We assessed these different mechanisms with a decomposition experiment using litter from four abundant species (Achnatherum sibiricum, Agropyron cristatum, Leymus chinensis and Stipa grandis) and litter mixtures representing treatment-specific community composition in a semi-arid grassland under long-term simulation of six different rates of N deposition. Decomposition increased consistently with increasing rates of N addition in all litter types. Higher soil manganese (Mn) availability, which apparently was a consequence of N addition-induced lower soil pH, was the most important factor for faster decomposition. Soil C : N ratios were lower with N addition that subsequently led to markedly higher bacterial to fungal ratios, which also stimulated litter decomposition. Several factors contributed jointly to higher rates of litter decomposition in response to N deposition. Shifts in plant species composition and litter quality played a minor role compared to N-driven reductions in soil pH and C : N, which increased soil Mn availability and altered microbial community structure. The soil-driven effect on decomposition reported here may have long-lasting impacts on nutrient cycling, soil organic matter dynamics and ecosystem functioning.


Asunto(s)
Ecosistema , Nitrógeno , Pradera , Hojas de la Planta , Plantas , Poaceae , Suelo
15.
Parasitol Res ; 120(11): 3749-3759, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-34499198

RESUMEN

Fatty acid uptake is extremely important for the survival and growth of the intracellular parasite Toxoplasma gondii. In this study, CRISPR-Cas9 gene editing technology was used to investigate the role of four lipid synthesis enzymes, namely, glycerol-3-phosphate dehydrogenase (G3PDH), malonyl CoA-acyl carrier protein transacylase (FabD), acyl-ACP thiolesterase (TE), and diacylglycerol acyltransferase (DGAT), in the virulence and infectivity of Type I RH and Type II Prugniaud (Pru) strains of T. gondii. Immunofluorescence analysis of the tachyzoite stage showed that FabD protein was located in the apicoplast; however, the expression level of the other three proteins was undetectable. Compared with wild-type (WT) strains, the growth of RHΔG3PDH, RHΔTE, and RHΔDGAT in vitro and their virulence in vivo were not significantly different. However, RHΔFabD exhibited a significantly reduced growth rate, compared with the WT strain. The deletion of FabD attenuated the virulence of Type II Pru strain and reduced the formation of cysts in vivo. These data improved our understanding of the role of lipid synthesis enzymes in the pathogenesis of T. gondii.


Asunto(s)
Parásitos , Toxoplasma , Animales , Sistemas CRISPR-Cas , Ácidos Grasos , Parásitos/metabolismo , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , Toxoplasma/genética , Toxoplasma/metabolismo , Virulencia
16.
Korean J Parasitol ; 59(4): 377-392, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34470089

RESUMEN

This paper is to illustrate the infestation and related ecological characteristics of chigger mites on the Asian house rat (Rattus tanezumi). A total of 17,221 chigger mites were collected from 2,761 R. tanezumi rats, and then identified as 131 species and 19 genera in 2 families. Leptotrombidium deliense, the most powerful vector of scrub typhus in China, was the first major dominant species on R. tanezumi. All the dominant mite species were of an aggregated distribution among different individuals of R. tanezumi. The species composition and infestations of chiggers on R. tanezumi varied along different geographical regions, habitats and altitudes. The species-abundance distribution of the chigger mite community was successfully fitted and the theoretical curve equation was S (R)=37e-(0.28R)2. The total chigger species on R. tanezumi were estimated to be 199 species or 234 species, and this further suggested that R. tanezumi has a great potential to harbor abundant species of chigger mites. The results of the species-plot relationship indicated that the chigger mite community on R. tanezumi in Yunnan was an uneven community with very high heterogeneity. Wide geographical regions with large host samples are recommended in the investigations of chigger mites.


Asunto(s)
Infestaciones por Ácaros , Tifus por Ácaros , Trombiculidae , Animales , China , Ecosistema , Infestaciones por Ácaros/veterinaria , Ratas
17.
Korean J Parasitol ; 59(6): 625-634, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34974669

RESUMEN

Based on the field investigations in 91 investigation sites (counties) in southwest China between 2001 and 2019, the present paper reported the chigger mites on A. agrarius mice in southwest China for the first time by using a series of statistical methods. From 715 striped field mice captured in 28 of 91 investigated sites, only 255 chiggers were collected, and they were identified as 14 species, 6 genera in 3 subfamilies under 2 families. Of 715 A. agrarius mice, only 24 of them were infested with chigger mites with low overall prevalence (PM=3.4%), overall mean abundance (MA=0.36 mites/host) and overall mean intensity (MI=10.63 mites/host). The species diversity and infestation of chiggers on A. agrarius were much lower than those previously reported on some other rodents in southwest China. On a certain species of rodent, A. agrarius mouse in southwest China seems to have a very low susceptibility to chigger infestations than in other geographical regions. Of 14 chigger species, there were 3 dominant species, Leptotrombidium sialkotense, L. rupestre and Schoengastiella novoconfuciana, which were of aggregated distribution among different individuals of A. agrarius hosts. L. sialkotense, one of 6 main vectors of scrub typhus in China, was the first dominant on A. agrarius. The species similarity of chigger mites on male and female hosts was low with CSS=0.25, and this reflects the sex-bias of different genders of A. agrarius mice in harboring different chigger species.


Asunto(s)
Infestaciones por Ácaros , Ácaros , Tifus por Ácaros , Trombiculidae , Animales , China/epidemiología , Femenino , Masculino , Ratones , Infestaciones por Ácaros/epidemiología , Infestaciones por Ácaros/veterinaria , Murinae
18.
Zhongguo Zhong Yao Za Zhi ; 46(15): 3980-3989, 2021 Aug.
Artículo en Zh | MEDLINE | ID: mdl-34472275

RESUMEN

To systematically review the efficacy of Xuebijing Injection combined with western medicine in the treatment of systemic inflammatory response syndrome(SIRS). In this study, CBM, CNKI, Wanfang, VIP, PubMed and EMbase databases were retrieved for clinical randomized controlled trials on the effect of Xuebijing Injection combined with western medicine in the treatment of SIRS from the establishment of the database to July 31, 2020. After screening, Meta-analysis was conducted by RevMan 5.3 software, trial sequential analysis was conducted by TSA 0.9.5.10 beta software, and the evidence quality level was evaluated by GRADEprofiler 3.6.1 software. Meta-analysis showed that Xuebijing Injection combined with western medicine could reduce white blood cell count(MD=-2.32, 95%CI[-2.44,-2.21], P<0.000 01), C-reactive protein count(MD=-22.70, 95%CI[-29.61,-15.79], P<0.000 01), APACHE Ⅱ score(MD=-2.15, 95%CI[-2.43,-1.87], P<0.000 01), tumor necrosis factor alpha count(SMD=-1.23, 95%CI[-1.48,-0.99], P<0.000 01) and interleukin-6 count(SMD=-0.92, 95%CI[-1.15,-0.69], P<0.000 01), improve treatment efficiency(RR=1.39, 95%CI[1.23, 1.56], P<0.000 01), reduce incidence of multiple organ dysfunction(RR=0.47, 95%CI[0.35, 0.64], P<0.000 01) and mortality(RR=0.22, 95%CI[0.13, 0.37], P<0.000 01), which were better than western medicine treatment alone. Trial sequential analysis showed that in terms of reducing the incidence of multiple organ dysfunction and C-reactive protein count, the cumulative Z value passed through the traditional threshold, TSA threshold and expected information value, and reached the required number of cases. GRADE evaluation showed that the level of evidence was low or very low. According to the findings, Xuebijing Injection combined with western medicine is effective in treating SIRS. However, as the low quality of the included studies may affect the reliability of the conclusion, more high-quality studies shall be included for further verification in the future, so as to provide better suggestions for clinical medication.


Asunto(s)
Medicamentos Herbarios Chinos , Humanos , Inyecciones , Ensayos Clínicos Controlados Aleatorios como Asunto , Reproducibilidad de los Resultados , Síndrome de Respuesta Inflamatoria Sistémica/tratamiento farmacológico
19.
Catheter Cardiovasc Interv ; 95(2): 282-293, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31714687

RESUMEN

OBJECTIVE: To evaluate the feasibility, safety, and effectiveness of a novel, absorbable atrial septal defect (ASD) closure device made of poly-l-lactic acid (PLLA) in a swine model of ASD and for the first time in humans. METHODS: A preclinical safety study was conducted using a swine model of ASD. In a clinical setting, five pediatric patients underwent ASD closure with the PLLA device with fluoroscopic and transthoracic echocardiography guidance. The procedural results and clinical outcomes at 1 day, 30 days, 3 months, and 6 months after closure were analyzed. RESULTS: The 24- and 36-month follow-up results of the preclinical study demonstrated that the PLLA device exhibited good endothelialization and degradability in the swine model. In the clinical study, successful device implantation was achieved in all five patients (median age, 3.6 years; range, 3.1-6.5 years). The mean defect size was (13.6 ± 2.7) mm. Follow-up at 30 days, 3 months, and 6 months was completed in all five cases. The complete defect closure rates with no residual shunt at 30 days, 3 months, and 6 months follow-up were 60% (3/5), 80% (4/5), and 80% (4/5), respectively. No device dislodgement, significant aortic valve or mitral valve regurgitation, new onset cardiac arrhythmia, or other adverse events were reported. CONCLUSION: The study results demonstrated that it is feasible to implant the PLLA device for closure of small to medium sized ASDs without significant residual shunts or severe adverse events in humans. The PLLA device exhibited good endothelialization and degradability in the swine model at 24 and 36 months. Further studies to evaluate long-term safety and effectiveness with the device in a large cohort of patients are warranted.


Asunto(s)
Implantes Absorbibles , Cateterismo Cardíaco/instrumentación , Defectos del Tabique Interatrial/terapia , Poliésteres/química , Animales , Cateterismo Cardíaco/efectos adversos , Niño , Preescolar , Modelos Animales de Enfermedad , Estudios de Factibilidad , Femenino , Defectos del Tabique Interatrial/diagnóstico por imagen , Defectos del Tabique Interatrial/fisiopatología , Humanos , Masculino , Diseño de Prótesis , Sus scrofa , Factores de Tiempo , Resultado del Tratamiento
20.
J Org Chem ; 85(2): 537-547, 2020 01 17.
Artículo en Inglés | MEDLINE | ID: mdl-31808693

RESUMEN

Direct conversion of the readily available alkyl bromides and alcohols to value-added epoxides using dimethyl sulfoxide (DMSO) under mild reaction conditions has been developed. Benzyl and allyl bromides, and activated and unactivated alcohols all proceeded smoothly to give epoxides in high to excellent yield. Dimethyl sulfide, generated by DMSO oxidations, was in situ elaborated to form the substituted dimethyl sulfonium ylide species that participates in the Corey-Chaykovsky epoxidation in a domino and one-pot fashion, respectively.

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