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Biomedical subjects

Wei Gao

Publications and source records attributed to Wei Gao.

At least 19 recordsLinked to original sources

MRDtarget: A heuristic Gaussian approach for optimizing targeted capture regions to enhance Minimal Residual Disease detection.

Molecular residual disease (MRD) detection, initially developed for hematologic malignancies, has become a critical biomarker for monitoring solid tumors. MRD detection primarily relies on circulating tumor DNA (ctDNA) analysis using next-generation sequencing, offering high sensitivity and broad genomic coverage. However, challenges remain in designing cost-effective panels that maximize mutation detection while maintaining biological relevance. Fixed panels often lack sufficient patient-specific mutation coverage, while WES-based personalized MRD assays, despite their high sensitivity, are costly and less accessible. We developed a tumor comprehensive genomic profiling (CGP)-informed personalized MRD assay to detect tumor-derived mutations, which allowed us to design patient-specific personalized panels and meanwhile, provide a cost-effective alternative to whole exome sequencing (WES). To address these limitations, we developed MRDtarget, a heuristic multivariate Gaussian model-based targeted capture region selection method. By expanding beyond traditional hotspot regions, MRDtarget optimizes variant tracking for MRD detection, significantly improving sensitivity. Using a Bayesian inference-based heuristic approach, MRDtarget integrates multi-feature informativeness rates to identify optimal genomic regions for capture. Experimental results demonstrate that MRDtarget enables the detection of more variants per patient. This study underscores the importance of rational panel design to improve MRD sensitivity and provides a novel approach to enhance precision diagnostics and treatment for solid tumor patients.

Humans↗

Genome-Wide Mining of lncRNAs Reveals Their Potential Regulatory Role in the Evolution of Viviparity.

Reproduction in vertebrates usually involves egg-laying (oviparity) or live-bearing (viviparity). Oviparity is the ancestral trait from which viviparity has independently evolved more than 100 times in squamate reptiles. This transition involves a series of physiological and structural changes, including the degeneration of eggshell and the evolution of a placenta and differences in the temporal and spatial expression patterns of some functional genes that drive the structural transformation. Long non-coding RNAs (lncRNAs) play important roles in the regulation of gene expression, yet it remains unclear whether they participate in gene expression shifts during the transition from oviparity to viviparity, and if so how. Therefore, we employ deep mining to identify novel lncRNAs of a closely related oviparous-viviparous pair of lizards (Phrynocephalus przewalskii and P. vlangalii). We construct cis- and trans-regulatory networks between lncRNAs and target genes using the transcriptomic data of oviduct or uteri tissues across reproductive periods. Results show that lncRNAs that regulate eggshell gland developmental genes in the oviparous lizard are lost or less expressed in the viviparous lizard. A number of lncRNAs involved in the regulation of placental development and embryo attachment in viviparous species have no orthologs in oviparous species, and others show little or no expression. Accordingly, lncRNAs may play important regulatory roles in the physiological and structural changes in the transition from oviparity to viviparity. These results open doors to the further elucidation of genetic regulatory networks.

Animals↗

HIV-1 drug resistance in variants from the female genital tract and plasma.

BACKGROUND: Human immunodeficiency virus type 1 (HIV-1) drug-resistance mutations may arise in a fraction of viral variants, and these variants may differ between compartments, including the genital tract and blood. METHODS: We studied 14 women with detectable HIV-1 in both the genital tract and plasma despite antiretroviral treatment. We obtained HIV-1 RNA sequences from 280 unique viral variants and then determined the resistance genotype and the predicted phenotype (Virtual Phenotype; Virco BVBA) of each variant. RESULTS: Eight patients (57%) displayed mutations conferring high-level HIV-1 drug resistance. Although we observed differences in specific mutations among viral variants, 13 of the 14 women showed highly concordant HIV-1 genotypic and predicted phenotypic resistance patterns in the 2 compartments. In 1 patient, resistance mutations appeared only in plasma; all variants in her genital tract, which displayed a low viral load, were susceptible. CONCLUSIONS: These data suggest that, for the majority of women, determination of HIV-1 drug resistance in the plasma will approximate the drug-resistance pattern in the genital tract. Analysis of individual variants enabled us to identify minority species bearing distinctive linked mutations, which may serve as a source of novel resistance genotypes. These data are relevant to clinical management and the evolution of drug resistance.

Adult↗

Contrast-enhanced magnetic resonance angiography of persistent fifth aortic arch in children.

BACKGROUND: Cine angiography and echocardiography have been utilized to diagnose congenital aortic arch anomalies. However, the visualization of great vessels by echocardiography is limited, while cine angiography requires cardiac catheterization with ionizing radiation. Contrast-enhanced magnetic resonance angiography (MRA) is a noninvasive modality suitable for visualization of congenital aortic arch anomalies. OBJECTIVE: To evaluate the utility of contrast-enhanced MRA in the diagnosis of persistent fifth aortic arch, a rare congenital aortic arch anomaly, and to compare the diagnostic accuracy of MRA with that of echocardiography and cine angiography. MATERIALS AND METHODS: In four pediatric patients, contrast-enhanced MRA studies were performed for diagnosing persistent fifth aortic arch. The findings of MRA were compared with echocardiographic findings and confirmed by cine angiography and operation. RESULTS: Transthoracic surface echocardiography noted an aberrant vessel arising from the ascending aorta in two of four patients; the etiology of this vessel was uncertain. In the other two patients a diagnosis of coarctation was made. Of the four patients, only one was diagnosed with interruption of the aortic arch. Contrast-enhanced MRA clarified uncertain echocardiographic findings, enabling the correct diagnosis of persistent fifth aortic arch with fourth aortic arch interruption in all four patients. CONCLUSION: Contrast-enhanced MRA is a safe, accurate, and fast imaging technique for the evaluation of persistent fifth aortic arch and may obviate the need for conventional cine angiography. Cardiac catheterization may be reserved for some types of complicated congenital heart disease and for obtaining hemodynamic information.

Aorta, Thoracic↗

[Value of monitoring oxygen metabolism in multiple organ dysfunction syndrome after severe trauma].

OBJECTIVE: To study changes in oxygen metabolism and evaluate metabolic status in tissue and cell after severe trauma, and to investigate value of monitoring oxygen metabolism in the course of development of multiple organ dysfunction syndrome (MODS) in trauma between patients. METHODS: The data of 146 patients with severe trauma in Tongji Hospital were collected. The variables pertaining to oxygen metabolism were analyzed, and the data were compared between patients with risky trauma and those with severe trauma, between patients complicated with MODS and non--MODS (NMODS), and between survivors and nonsurvivors. With patients with minor trauma as control, the data were analyzed according to injury severity score (ISS), revised trauma score (RTS), acute physiology and chronic health evaluation II (APACHE II), trauma and injury severity score (TRISS(RTS)) methods for trauma and outcome study of probability of survival (Ps). RESULTS: Oxygen metabolism abnormality was found after trauma, and it was correlated with ISS, RTS, injured organ or region and number of injured organs, shock, systemic inflammatory response syndrome (SIRS) and respiratory complications. It was more intense in the patients with MODS. There was marked difference in the ratio of change in oxygen metabolism between MODS and NMODS groups. Oxygen deficiency metabolic variables tended to deteriorate in the non survival group. More marked changes in metabolic variables indicated severer organ dysfunction, reaching their peak values before death. CONCLUSION: Changes in level of oxygen metabolism might be closely correlated with development of MODS in trauma patients. Dynamic monitorings of metabolic status of tissue and cell are valuable in predicting the development of MODS after severe trauma.

Adolescent↗

Design, synthesis, and evaluation of a potent, cell-permeable, conformationally constrained second mitochondria derived activator of caspase (Smac) mimetic.

A potent, cell-permeable, conformationally constrained second mitochondria derived activator of caspase mimetic (SM-131, 2) has been designed, synthesized, and evaluated. Compound 2 binds to X-linked inhibitors of apoptosis proteins (XIAP) with a Ki of 61 nM in a competitive binding assay and directly antagonizes the XIAP inhibition of caspase-9 activity in a cell-free functional assay. Compound 2 achieves an IC50 of 100 nM in inhibition of cell growth and effectively induces cell death in the MDA-MB-231 human breast cancer cell line.

Azepines↗

Octameric structure of the human bifunctional enzyme PAICS in purine biosynthesis.

Phosphoribosylaminoimidazole carboxylase/phosphoribosylaminoimidazole succinocarboxamide synthetase (PAICS) is an important bifunctional enzyme in de novo purine biosynthesis in vertebrate with both 5-aminoimidazole ribonucleotide carboxylase (AIRc) and 4-(N-succinylcarboxamide)-5-aminoimidazole ribonucleotide synthetase (SAICARs) activities. It becomes an attractive target for rational anticancer drug design, since rapidly dividing cancer cells rely heavily on the purine de novo pathway for synthesis of adenine and guanine, whereas normal cells favor the salvage pathway. Here, we report the crystal structure of human PAICS, the first in the entire PAICS family, at 2.8 A resolution. It revealed that eight PAICS subunits, each composed of distinct AIRc and SAICARs domains, assemble a compact homo-octamer with an octameric-carboxylase core and four symmetric periphery dimers formed by synthetase domains. Based on structural comparison and functional complementation analyses, the active sites of SAICARs and AIRc were identified, including a putative substrate CO(2)-binding site. Furthermore, four symmetry-related, separate tunnel systems in the PAICS octamer were found that connect the active sites of AIRc and SAICARs. This study illustrated the octameric nature of the bifunctional enzyme. Each carboxylase active site is formed by structural elements from three AIRc domains, demonstrating that the octamer structure is essential for the carboxylation activity. Furthermore, the existence of the tunnel system implies a mechanism of intermediate channeling and suggests that the quaternary structure arrangement is crucial for effectively executing the sequential reactions. In addition, this study provides essential structural information for designing PAICS-specific inhibitors for use in cancer chemotherapy.

Amino Acid Sequence↗

Impaired acute and inflammatory nociception in mice lacking the p50 subunit of NF-kappaB.

The transcription factor NF-kappaB is thought to play an essential role in inflammatory processes and pain. However, the in vivo function of individual NF-kappaB subunits in the development and processing of nociceptive responses is not clarified. In this study we investigated the role of the p50 subunit of NF-kappaB in models of acute and persistent nociception using NF-kappaB p50(-/-) mice. We found that these mice showed impaired basal responses to mechanical as well as thermal noxious stimulation in the dynamic plantar as well as the hot plate test, respectively, in comparison with wild-type mice. In the formalin test we observed a decreased nociceptive behavior in the first and the second phase in NF-kappaB p50(-/-) mice. In a model of persistent inflammatory hyperalgesia these mice also showed a reduced hyperalgesia to a thermal stimulus, which was in accordance with a lower cyclooxygenase-2 expression in the spinal cord after peripheral inflammatory stimulation. Taken together, our data indicate that the p50 subunit of NF-kappaB is of importance in acute and persistent inflammatory pain. The participation to persistent pain might rely on activation of NF-kappaB by inflammatory stimuli while the contribution to acute pain responses might be related to constitutive NF-kappaB activity in neurons of the nociceptive system.

Animals↗

Structure-based design of potent small-molecule inhibitors of anti-apoptotic Bcl-2 proteins.

A structure-based approach was employed to design a new class of small-molecule inhibitors of Bcl-2. The most potent compound 5 (TW-37) binds to Bcl-2 with a K(i) value of 290 nM and also to Bcl-xL and Mcl-1 with high affinities. Compound 5 potently inhibits cell growth in PC-3 prostate cancer cells with an IC(50) value of 200 nM and effectively induces apoptosis in a dose-dependent manner.

Apoptosis↗

The role of the CD95, CD38 and TGFbeta1 during active human cytomegalovirus infection in liver transplantation.

AIM: Human cytomegalovirus (HCMV) has highly evolved mechanisms for avoiding detection by the host immune system. The aim of this study was to analyze the expression levels of TGFbeta1, soluble form of CD95, CD95 ligand (sCD95 and sCD95L, respectively) in plasma and CD95 expression on CD3(+) cells, CD38 expression on CD8(+) cells in liver transplanted recipients with active HCMV infection. METHODS: Blood samples were collected from 15 liver transplanted recipients with active HCMV infection and 15 recipients without HCMV infection. CD95 expression on CD3(+) cells and CD38 expression on CD8(+) cells were quantitatively detected with two-color fluorescence activated cell sorter (FACS) analysis. Lymphocyte surface phenotypes of CD4 and CD8 were detected with FACS analysis. Plasma sCD95, sCD95L and TGFbeta1 levels were determined with enzyme linked-immuno-sorbent assay (ELISA). The results were compared with that from 15 healthy individuals. RESULTS: CD95 expression on CD3(+) T-cells and CD38 expression on CD8(+) cells were significantly increased in active HCMV infection group compared with that in stable group or healthy group (P<0.01). No significant difference was seen between stable group and healthy group (P>0.05). The percentages of CD4(+) T-cell and CD4/CD8 ratio in active HCMV infection group were significantly lower than the values in stable group and healthy group (P<0.05). Plasma levels of TGFbeta1 and sCD95 were significantly increased in active HCMV infection group compared to stable group and healthy group (P<0.05). In contrast, plasma levels of sCD95L in healthy group were not significantly different from that expressed in active HCMV infection group and stable group (P>0.05). CONCLUSION: HCMV suppress proliferation of activated T cells by apoptosis and by releasing immunosuppressive cytokine TGFbeta1. This may provide an important clue to a better understanding of the pathogenesis in liver transplanted recipients with active HCMV infection.

ADP-ribosyl Cyclase 1↗

Screening for genes essential for mouse embryonic stem cell self-renewal using a subtractive RNA interference library.

The pluripotency of mouse embryonic stem (ES) cells is maintained by self-renewal. To screen for genes essential for this process, we constructed an RNA interference (RNAi) library by inserting subtracted ES cell cDNA fragments into plasmid containing two opposing cytomegalovirus promoters. ES cells were transfected with individual RNAi plasmids and levels of the pluripotency marker Oct-4 were monitored 48 hours later by real time RT-PCR. Of the first 89 RNAi plasmids characterized, 12 downregulated Oct-4 expression to less than 50% of the normal level and 7 of them upregulated Oct-4 expression to more than 150% of the normal level. To investigate their long-term effect on self-renewal, ES cells were transfected by these 19 RNAi plasmids individually and G418-resistant colonies were subjected to alkaline phosphatase (AP) staining after 7 days selection. Except for 4 plasmids that caused cell death, the ratio of AP positive colonies was repressed to less than 60% of the control group by the other 15 plasmids and even below 20% by 10 plasmids. The cDNA fragments in these 10 plasmids correspond to eight genes, including Zfp42/Rex-1, which was chosen for further functional analysis. RNAi knockdown of Zfp42 induced ES cells differentiate to endoderm and mesoderm lineages, and overexpression of Zfp42 also caused ES cells to lose the capacity of self-renewal. Our results indicate that RNAi screen is a feasible and efficient approach to identify genes involved in ES cells self-renewal. Further functional characterization of these genes will promote our understanding of the complex regulatory networks in ES cells.

Animals↗

Colloids seeded deposition: growth of titania nanotubes in solution.

The formation of titania nanotubes through CeO2 colloids seeded deposition process in solution has been demonstrated. The interactions among colloidal particles play important roles for the solution "VLS"-type growth of nanotubes. The observation has significance for understanding solution nucleation and for developing new methods for nanomaterials preparation via the disclosed colloids seeded deposition (CSD) mechanism.

Journal Article↗

Gender differences in the renal response to renin-angiotensin system blockade.

Evidence suggests that gender differences exist in renin-angiotensin system (RAS) function. It was hypothesized that women may differ also in their response to RAS blockade. The renal and peripheral hemodynamic responses to incremental dosages of an angiotensin receptor blocker and the degree of angiotensin II (AngII) insensitivity achieved during 8 wk were examined in men and women. Participants were 30 young healthy men (n = 15; mean age 27 +/- 2) and women (n = 15; mean age 28 +/- 2) who were on a controlled sodium and protein diet for 1 wk before each study. The humoral, renal, and systemic response to incremental dosages of irbesartan (75 mg for 4 wk, then 150 mg for 4 wk) was assessed, as was the pressor response to AngII (3 ng/kg per min), at 2-wk intervals. AngII type 1 receptor expression in skin biopsies was assessed at baseline and after 8 wk by a real-time PCR protocol. Men and women both exhibited significant declines in BP. Women achieved significantly reduced AngII sensitivity compared with men at lower dosages, showing no pressor response at 4 wk of 75 mg/d irbesartan, whereas men continued to exhibit a pressor response at 4 wk of 150 mg/d. Receptor expression at baseline did not differ between men and women but by 8 wk was significantly decreased in women and unchanged in men. Our findings indicate that men may require larger dosages of angiotensin receptor blocker than do women and that the BP response cannot be used as a surrogate marker for adequate RAS blockade of the renal microvasculature.

Adult↗

Electrochemiluminescence determination of pipemidic acid using sulfite as energy transfer mediator.

An electrochemiluminescence (ECL) based on energy transfer from electro-generated triplet sulfur dioxide to pipemidic acid (PPA) was studied. A weak ECL from triplet sulfur dioxide (3)SO2 * was observed when sulfite was electrochemically oxidized in sulfuric acid solution on a Pt electrode. When PPA was present, the weak ECL was enhanced. The enhanced ECL was attributed to energy transfer from (3)SO2 * to PPA. Based on the enhanced ECL, a flow-injection (FIA) ECL method for the determination of PPA was proposed. The proposed method allowed the measurement of PPA over the range of 1.0x10(-7) to 2.0x10(-5)moll(-1). The detection limit was 3.9x10(-8)moll(-1), and the relative standard deviation for 1.0x10(-6)moll(-1) PPA (n=9) was 1.3%. This method was evaluated by the analysis of PPA in pharmaceutical preparations and urine samples.

Energy Transfer↗

Regulation of acetylcholinesterase expression by calcium signaling during calcium ionophore A23187- and thapsigargin-induced apoptosis.

We have recently reported that acetylcholinesterase expression was induced during apoptosis in various cell types. In the current study we provide evidence to suggest that the induction of acetylcholinesterase expression during apoptosis is regulated by the mobilization of intracellular Ca(2+). During apoptosis, treatment of HeLa and MDA-MB-435s cells with the calcium ionophore A23187 resulted in a significant increase in acetylcholinesterase mRNA and protein levels. Chelation of intracellular Ca(2+) by BAPTA-AM (1,2-bis-(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester), an intracellular Ca(2+) chelator, inhibited acetylcholinesterase expression. A23187 also enhanced the stability of acetylcholinesterase mRNA and increased the activity of acetylcholinesterase promoter, effects that were blocked by BAPTA-AM. Perturbations of cellular Ca(2+) homeostasis by thapsigargin resulted in the increase of acetylcholinesterase expression as well as acetylcholinesterase promoter activity during thapsigargin induced apoptosis in HeLa and MDA-MB-435s cells, effects that were also inhibited by BAPTA-AM. We further demonstrated that the transactivation of the human acetylcholinesterase promoter by A23187 and thapsigargin was partially mediated by a CCAAT motif within the -1270 to -1248 fragment of the human acetylcholinesterase promoter. This motif was able to bind to CCAAT binding factor (CBF/NF-Y). These results strongly suggest that cytosolic Ca(2+) plays a key role in acetylcholinesterase regulation during apoptosis induced by A23187 and thapsigargin.

Acetylcholinesterase↗

Discovery of a nanomolar inhibitor of the human murine double minute 2 (MDM2)-p53 interaction through an integrated, virtual database screening strategy.

An integrated, virtual database screening strategy has led to 7-[anilino(phenyl)methyl]-2-methyl-8-quinolinol (4, NSC 66811) as a novel inhibitor of the murine double minute 2 (MDM2)-p53 interaction. This quinolinol binds to MDM2 with a Ki of 120 nM and activates p53 in cancer cells with a mechanism of action consistent with targeting the MDM2-p53 interaction. It mimics three p53 residues critical in the binding to MDM2 and represents a promising new class of non-peptide inhibitors of the MDM2-p53 interaction.

Aniline Compounds↗

Structure-based design of spiro-oxindoles as potent, specific small-molecule inhibitors of the MDM2-p53 interaction.

Potent, specific, non-peptide small-molecule inhibitors of the MDM2-p53 interaction were successfully designed. The most potent inhibitor (MI-63) has a K(i) value of 3 nM binding to MDM2 and greater than 10,000-fold selectivity over Bcl-2/Bcl-xL proteins. MI-63 is highly effective in activation of p53 function and in inhibition of cell growth in cancer cells with wild-type p53 status. MI-63 has excellent specificity over cancer cells with deleted p53 and shows a minimal toxicity to normal cells.

Antineoplastic Agents↗