Biomedical subjects

Yong Yan

Publications and source records attributed to Yong Yan.

6 recordsLinked to original sources

PubMed2026

A complete hlyCABD-like RTX operon marks a virulence-associated subset of trh-positive Vibrio parahaemolyticus from Hangzhou Bay, China.

Vibrio parahaemolyticus remains a major cause of seafood-associated gastroenteritis, yet routine surveillance still relies largely on the canonical hemolysin markers thermostable direct hemolysin (tdh) and tdh-related hemolysin (trh). To determine whether this framework overlooks accessory virulence determinants in trh-positive lineages, we analyzed 193 V. parahaemolyticus isolates collected between 2022 and 2025 from clinical, environmental, and seafood-associated sources in the Hangzhou Bay region of China. Serotyping identified 45 serotypes, with O10:K4 predominating among clinical isolates. Both clinical and non-clinical populations showed open pan-genomes, although the non-clinical group carried a larger accessory gene pool. We identified a complete hlyCABD-like RTX operon in 10 trh-positive isolates with T3SS2-associated virulence backgrounds. These RTX-positive isolates were distributed across seven sequence types and three of five phylogenetic groups. This distribution was lineage-restricted but non-clonal. In the representative hybrid-assembled genome, the operon occurred within a mosaic genomic region containing additional virulence- and mobility-associated genes, indicating a composite pathogenicity island-like element. In the tested subset, RTX-positive isolates showed significantly greater hemolytic activity than RTX-negative trh-positive isolates. This significant difference was consistently observed in both plate-based and liquid assays, and within the RTX-positive subset, hlyA expression correlated with hemolytic activity, whereas the trh gene and the tlh (thermolabile hemolysin) gene did not. A complete hlyCABD-like RTX operon therefore identifies a hemolysis-associated subset of trh-positive V. parahaemolyticus and supports its further evaluation as an additional target for food safety surveillance.

Vibrio parahaemolyticus↗

PubMed2006

Synthesis and photovoltaic properties of two-dimensional conjugated polythiophenes with bi(thienylenevinylene) side chains.

Three two-dimensional (2-D) conjugated polythiophenes with bi(thienylenevinylene) side chains (biTV-PTs), P1, P2, and P3, were designed and synthesized for application in polymer solar cells. The absorption spectral, electrochemical, and photovoltaic properties of the biTV-PTs were investigated and compared with those of poly(3-hexylthiophene) (P3HT). The biTV-PTs show a broad absorption band from 350 to 650 nm; especially, the absorption spectrum of P3 displays a broad plateau and much stronger absorbance than that of P3HT in the wavelength range from 350 to 480 nm. Cyclic voltammograms reveal that the onset oxidation and reduction potentials of the biTV-PTs positively shifted by ca. 0.2 V in comparison with those of P3HT, indicating that the HOMO energy level of the biTV-PTs is ca. 0.2 eV lower than that of P3HT. Polymer solar cells (PSCs) were fabricated based on the blend of the polymers and 1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-C-61 (PCBM) with a weight ratio of 1:1. The open circuit voltage of the PSCs based on the biTV-PTs is ca. 0.1 V higher than that of P3HT, which is benefited from the lower HOMO levels of the biTV-PTs. The maximum power conversion efficiency (PCE) of the PSCs based on P3 reached 3.18% under AM 1.5, 100 mW/cm2, which is 38% increased in comparison with that (2.41%) of the devices based on P3HT under the same experimental conditions. The results indicate that the 2-D conjugated biTV-PTs are promising polymer photovoltaic materials.

Journal Article↗

PubMed2005

[Research progresses on deformable model in medical image processing].

In recent years, image processing technique based on deformable models has been widely used in the field of medical image processing and analysis. This survey demonstrates the principle of two kinds of basic deformable models, i.e. parametric deformable model and geometric deformable model. The design of model in application is also discussed. By incorporating prior knowledge and modeling global properties, several new extensions of basic deformable model are then reviewed. At last, some prospects of possible research are given.

Computer Simulation↗

PubMed2004

Antiepileptic drug-induced multidrug resistance P-glycoprotein overexpression in astrocytes cultured from rat brains.

BACKGROUND: Intractable epilepsy may be due to multidrug resistance induced by conventional antiepileptic drugs. The phenomenon is sometimes associated with an overexpression of multidrug resistance gene 1 (MDR1). The purpose of this study was to determine if the overexpression of MDR1 could be induced in astrocytes from rat brains in vitro using antiepileptic drugs. METHODS: Astrocyte cell cultures from postnatal Wistar rats (within 24 hours of birth) were established. Different concentrations of the antiepileptic drugs phenytoin, phenobarbital, carbamazepine, and valproic acid were added to the cultures for 10, 20, or 30 days. The expression of P-glycoprotein (Pgp), the protein product of MDR1, was investigated with immunocytochemistry. RESULTS: Less than 5% of normal, untreated astrocytes had detectable Pgp staining at any time point. Phenytoin, phenobarbital, carbamazepine, and valproic acid induced the overexpression of Pgp in astrocytes in a dose- and time-dependent manner. Significantly higher levels of Pgp staining were detected at therapeutic concentrations of certain antiepileptic drugs (20 microg/ml phenobarbital, 40 microg/ml phenobarbital, and 20 microg/ml phenytoin) on day 30. Upregulation of Pgp was detected when using higher concentrations of phenytoin, phenobarbital, and valproic acid on day 20 and when using higher concentrations of any of the four antiepileptic drugs on day 30. CONCLUSIONS: Treatment with antiepileptic drugs may contribute to the overexpression in astrocytes of MDR1 and its protein product, Pgp. The mechanism leading to MDR must be considered in patients undergoing long-term treatment with antiepileptic drugs.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2002

Effects of intravenous mannitol on EEG recordings in stroke patients.

OBJECTIVES: To evaluate the usefulness of continuous EEG monitoring of stroke patients during and after intravenously infused mannitol. METHODS: Patients were rapidly administered 50 g of intravenous mannitol solution with continuous EEG monitoring for 3h pre- and post-drug infusion in the neurological intensive care unit. Visual and spectral analyses of EEG recording pre- and post-mannitol infusion were carried out. RESULTS: The study consisted of 47 patients. Of 38 patients with intracranial hemorrhage, 33 had abnormal EEG findings pre-mannitol administration. After mannitol therapy, visual analysis of the drug-induced EEG changes showed that the EEG findings were unchanged in 13 patients, demonstratively improved in 22 patients, and worse in 3 patients. The spectral analysis demonstrated that mannitol-induced EEG changes increased in alpha power and decreased in delta power in the lesion hemispheres, especially in the central and middle temporal areas. Maximal effects occurred 30 min post-mannitol infusion, and remained significant for 2h post-infusion. Of the 9 patients with cerebral infarction, only one with diffuse background slowing of one-side dominance pre-mannitol improved after the infusion of mannitol. CONCLUSIONS: The results of our investigation indicated that continuous EEG monitoring of mannitol treatment can reflect the brain edema, raised ICP in stroke patients, and provide assessment the drugs effects of antiedema and intracranial pressure lowering in vivo.

Adult↗

PubMed2002

Effects of intravenous human albumin and furosemide on EEG recordings in patients with intracerebral hemorrhage.

OBJECTIVES: To characterize alterations in continuous EEG monitoring that occurs during and after intravenous infusion of human albumin or furosemide in patients with intracerebral hemorrhage. METHODS: Patients were rapidly administered 20% human albumin 50 ml or furosemide 40 mg intravenously with continuous EEG monitoring for 3h before and after drug infusion in the neurological intensive care unit. Visual and spectral analyses of EEG recordings before and after mannitol administration were carried out. RESULTS: The study consisted of 20 patients. Of 14 patients with human albumin treatment, a decrease in the slowing activity was visually noted in 9 cases after the drug infusion. The spectral analysis demonstrated that albumin-induced EEG changes increased in alpha power and decreased in delta power in the lesion hemispheres, especially in the central and middle temporal areas. The effects occurred after 30 min and were maximal 1h after the end of the infusion, then remained significant for 2h post-infusion. Of 6 patients with furosemide treatment, the EEG recordings before, during, and after the furosemide infusion were not statistically significantly different by visual and quantitative analyses. CONCLUSIONS: The results support the opinion that the available EEG monitoring techniques offer an inexpensive, non-invasive, and consistently reproducible technique for reflecting the therapeutic effects of therapeutics in lowering ICP and antiedema in stroke patients.

Aged↗