Biomedical subjects

Liang Peng

Publications and source records attributed to Liang Peng.

15 recordsLinked to original sources

PubMed2026

Advancing precision tacrolimus therapy: a systems genetics dissection in BXD platform.

BACKGROUND: Tacrolimus is a core immunosuppressant in organ transplantation, but its narrow therapeutic window and significant pharmacokinetic variability hinder precision dosing. Although CYP3A5-guided strategies have established clinical relevance for tacrolimus initial dose adjustment, they do not fully account for the marked interindividual variability in tacrolimus exposure, highlighting the need for complementary models to decode more complex genetic regulation. This study aimed to identify candidate genetic modulators of tacrolimus metabolism and develop an integrated predictive framework for individualized therapy. METHODS: Using 46 BXD recombinant inbred mouse strains, we characterized transcriptomics and machine learning, and validated key genes. We then constructed a clinical model using data from 168 renal transplant recipients. RESULTS: We identified 19 genomic loci associated with tacrolimus pharmacokinetic traits and supported DBP/CYP2A6 as candidate modulators associated with tacrolimus disposition. The clinical prediction model, incorporating these genes and clinical variables, achieved robust AUROC. CONCLUSIONS: These findings support a polygenic contribution to tacrolimus metabolism and provide an experimental and computational framework for identifying candidate modulators relevant to individualized dosing. The BXD mouse platform offers a systems-genetics approach for mechanistic discovery that may inform future translational studies on tacrolimus precision dosing.

Animals↗

PubMed2026

Assembly and Characterization of the First Complete Mitochondrial Genome of Tussilago farfara L.: Insights into Biological Functions and Phylogenetic Relationships within the Asteraceae Family.

Tussilago farfara L., a member of the Asteraceae family, is an economically valuable species due to its edible and medicinal properties. To elucidate the structural characteristics, genetic mechanisms, and evolutionary pathways of the organelle genomes of T. farfara, we sequenced, assembled, and annotated its mitochondrial genome for the first time. The complete mitochondrial genome of T. farfara spans 306,024 bp and contains 33 mitochondrial protein-coding genes (PCGs), 3 rRNAs, and 22 tRNAs. Analysis of the nucleotide substitution rate and genetic diversity revealed that most mitochondrial genome genes may have undergone purifying selection, indicating a slow evolutionary rate and a relatively conserved genomic structure. We further identified 13 fragments of chloroplast-derived DNA integrated into the mitochondrial genome, evidencing intracellular gene transfer. Collinearity analysis showed that Arctium lappa shares the most extensive mitochondrial homologous sequences and the highest sequence similarity with T. farfara. Phylogenetic analysis based on the mitochondrial genome helped to clarify the evolutionary and taxonomic position of T. farfara within the Asteraceae family. The mitochondrial genome sequence of T. farfara provides a valuable genomic resource for species identification and for evolutionary studies within the Asteraceae family.

Genome, Mitochondrial↗

PubMed2024

No causal relationship between glucose and inflammatory bowel disease: a bidirectional two-sample mendelian randomization study.

BACKGROUND: Association between glucose and inflammatory bowel disease (IBD) was found in previous observational studies and in cohort studies. However, it is not clear whether these associations reflect causality. Thus, this study investigated whether there is such a causal relation between elevated glucose and IBD, Crohn's disease (CD) and ulcerative colitis (UC). METHODS: We performed a two-sample Mendelian Randomization (MR) with the independent genetic instruments identified from the largest available genome-wide association study (GWAS) for IBD (5,673 cases; 213,119 controls) and its main subtypes, CD and UC. Summarized data for glucose which included 200,622 cases and glycemic traits including HbA1c and type 2 diabetes(T2DM) were obtained from different GWAS studies. Primary and secondary analyses were conducted by preferentially using the radial inverse-variance weighted (IVW) approach. A number of other meta-analysis approach and sensitivity analyses were carried out to assess the robustness of the results. RESULTS: We did not find a causal effect of genetically predicted glucose on IBD as a whole (OR 0.858; 95% CI 0.649-1.135; P = 0.286). In subtype analyses glucose was also suggestively not associated with Crohn's disease (OR 0.22; 95% CI 0.04-1.00; P = 0.05) and ulcerative colitis (OR 0.940; 95% CI 0.628-1.407; P = 0.762). In the other direction, IBD and its subtypes were not related to glucose and glycemic traits. CONCLUSIONS: This MR study is not providing any evidence for a causal relationship between genetically predicted elevated glucose and IBD as well as it's subtypes UC and CD. Regarding the other direction, no causal associations could be found. Future studies with robust genetic instruments are needed to confirm this conclusion.

Humans↗

PubMed2006

Energy metabolism in astrocytes: high rate of oxidative metabolism and spatiotemporal dependence on glycolysis/glycogenolysis.

Astrocytic energy demand is stimulated by K(+) and glutamate uptake, signaling processes, responses to neurotransmitters, Ca(2+) fluxes, and filopodial motility. Astrocytes derive energy from glycolytic and oxidative pathways, but respiration, with its high-energy yield, provides most adenosine 5' triphosphate (ATP). The proportion of cortical oxidative metabolism attributed to astrocytes ( approximately 30%) in in vivo nuclear magnetic resonance (NMR) spectroscopic and autoradiographic studies corresponds to their volume fraction, indicating similar oxidation rates in astrocytes and neurons. Astrocyte-selective expression of pyruvate carboxylase (PC) enables synthesis of glutamate from glucose, accounting for two-thirds of astrocytic glucose degradation via combined pyruvate carboxylation and dehydrogenation. Together, glutamate synthesis and oxidation, including neurotransmitter turnover, generate almost as much energy as direct glucose oxidation. Glycolysis and glycogenolysis are essential for astrocytic responses to increasing energy demand because astrocytic filopodial and lamellipodial extensions, which account for 80% of their surface area, are too narrow to accommodate mitochondria; these processes depend on glycolysis, glycogenolysis, and probably diffusion of ATP and phosphocreatine formed via mitochondrial metabolism to satisfy their energy demands. High glycogen turnover in astrocytic processes may stimulate glucose demand and lactate production because less ATP is generated when glucose is metabolized via glycogen, thereby contributing to the decreased oxygen to glucose utilization ratio during brain activation. Generated lactate can spread from activated astrocytes via low-affinity monocarboxylate transporters and gap junctions, but its subsequent fate is unknown. Astrocytic metabolic compartmentation arises from their complex ultrastructure; astrocytes have high oxidative rates plus dependence on glycolysis and glycogenolysis, and their energetics is underestimated if based solely on glutamate cycling.

Animals↗

PubMed2006

[High throughput screening and analysis of prostate cancer-related genes through mining databases].

BACKGROUND & OBJECTIVE: Investigation of differentially expressed genes in prostate cancer tissues may help to understand the molecular mechanism of prostate cancer and provide diagnostic markers or new targets for therapy. The Cancer Genome Anatomy Project (CGAP) public database provides an unprecedented opportunity for cancer researchers to mine genes differentially expressed in cancer tissues by bioinformatic methods. This study was to explore the feasibility of incorporating the Internet-available Serial Analysis of Gene Expression (SAGE) and cDNA databases to find human prostate cancer-related genes. METHODS: SAGE digital gene expression displayer (DGED) and cDNA DGED were used to analyze differentially expressed (>5 folds) genes in malignant prostate tissues compared with normal prostate tissues. The SAGE tags were filtered by their confidence and our 3 criteria. To test the confidence of tags of virtual digital analysis for gene identification, the modified GLGI (generation of longer cDNA fragments from SAGE tags for gene identification) was used to get the cDNA 3' end downstream of 20 tags. Main functions of all candidate genes and their relations to prostate cancer were annotated. RESULTS: Fifty-three differentially expressed genes were screened out by SAGE DGED, 26 of them were up-regulated and 27 were down-regulated in prostate cancer; 28 differentially expressed genes were got by cDNA DGED, 15 of them were up-regulated and 13 were down-regulated in prostate cancer. CONCLUSION: Reasonable use of public databases by the Internet-available tools is a simple, effective approach to get cancer-related genes, and might provide useful clues for further investigation although the results require experimental validation.

DNA, Complementary↗

PubMed2006

[Effects of prenatal exposure to low level lead on learning and memory of rats' offspring].

OBJECTIVE: To explore the effects of prenatal exposure to low level lead on learning and memory of rat's offspring. METHODS: The pregnant rats were randomizedly divided into 4 groups and provided with doubly evaporated water in the control group and 125, 250 and 500 mg/L lead acetate solution via drinking water in three exposed groups respectively during the pregnancy. The learning and memory ability of 21-day old and 60-day old offsprings were tested by the Morris water maze and the shuttling and avoiding dark box respectively. RESULTS: The blood and hippocampus lead concentrations of 1-day old and 21-day old offspring in the 3 lead-exposed groups were significantly increased compared with the control group (P < 0.05), while at the period of 60-day old there was no significant difference between them. The time to find the platform in Morris water maze for 21-day old and 60-day old offsprings of the 3 lead in the exposed groups was significantly increased compared with the control group during the 4 days training (P < 0.05). The times of initiative avoiding in the shuttling and avoiding dark box for 21-day old and 60-day old offsprings in the 3 lead-exposed groups were significantly decreased, while the latency of the initiative avoiding and latency of the passive avoiding were significantly increased compared with the control group (P < 0.05). CONCLUSION: Prenatal exposure to low level lead impaired the space learning and memory ability of offsprings of the rats, and this kind of influence will continue till the offspring's maturity.

Animals↗

PubMed2005

Reduction of MTT by flavonoids in the absence of cells.

The tetrazolium salt 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) is used to determine cell viability in assays of cell proliferation and cytotoxicity. MTT is reduced in metabolically active cells to yield an insoluble purple formazan product. However, in this study, using a colorimetric method with MTT, we demonstrated that luteolin and quercetin (both are flavonoids) can reduce MTT in the absence of living cells. We also examined effects of some experimental conditions on the reaction, such as concentrations of flavonoids, incubation time, the structure and the existing form in solvents of flavonoids. The maximal absorbance values, which were 0.355 (luteolin) and 0.491 (quercetin), were observed when the concentrations of flavonoids were 200 microg/ml. Incubating MTT with flavonoids for 8 h, the absorbance values got the maximum, which were 0.320 (luteolin) and 0.398 (quercetin). The ability of flavonoids reducing MTT in RPMI-1640 with 10% fetal calf serum was higher than that in anhydrous ethanol. And the ability of quercetin reducing MTT was higher than that of luteolin both in RPMI-1640 with 10% fetal calf serum and anhydrous ethanol. Based on the results, this undescribed reaction can significantly influence the results of experiments using the MTT assay to measure the effects of flavonoids on cell growth.

Cell Survival↗

PubMed2005

Comparison of isotropic and orthotropic material property assignments on femoral finite element models under two loading conditions.

CT data has been widely used in the finite element modeling of bone. It can provide useful information on the geometrical topology and material properties of bone. Based on CT data, the assignment of bone material properties to finite element meshes is a fundamental step in the model generation. Most work done in this area has adopted isotropic assignment strategy due to its simplicity. However, bone material has been recognized as an orthotropic material. This work is aimed to investigate the effects of orthotropic material property assignment on femoral finite element model by comparing with isotropic material property assignment on the same model. There were 72 finite element models obtained from the frozen CT male dataset of visible human project. Based on the analysis results of the maximum equivalent Von Mises stress and the maximum nodal displacement, three parameters were defined to achieve this comparison. The results have shown that the differences between the two material property assignments are small under two loading conditions (double-leg standing and single-leg standing) investigated in this work.

Adult↗

PubMed2005

Nucleoside transporter expression and function in cultured mouse astrocytes.

Uptake of purine and pyrimidine nucleosides in astrocytes is important for several reasons: (1) uptake of nucleosides contributes to nucleic acid synthesis; (2) astrocytes synthesize AMP, ADP, and ATP from adenosine and GTP from guanosine; and (3) adenosine and guanosine function as neuromodulators, whose effects are partly terminated by cellular uptake. It has previously been shown that adenosine is rapidly accumulated by active uptake in astrocytes (Hertz and Matz, Neurochem Res 14:755-760, 1989), but the ratio between active uptake and metabolism-driven uptake of adenosine is unknown, as are uptake characteristics for guanosine. The present study therefore aims at providing detailed information of nucleoside transport and transporters in primary cultures of mouse astrocytes. Reverse transcription-polymerase chain reaction identified the two equilibrative nucleoside transporters, ENT1 and ENT2, together with the concentrative nucleoside transporter CNT2, whereas CNT3 was absent, and CNT1 expression could not be investigated. Uptake studies of tritiated thymidine, formycin B, guanosine, and adenosine (3-s uptakes at 1-4 degrees C to study diffusional uptake and 1-60-min uptakes at 37 degrees C to study concentrative uptake) demonstrated a fast diffusional uptake of all four nucleosides, a small, Na(+)-independent and probably metabolism-driven uptake of thymidine (consistent with DNA synthesis), larger metabolism-driven uptakes of guanosine (consistent with synthesis of DNA, RNA, and GTP) and especially of adenosine (consistent with rapid nucleotide synthesis), and Na(+)-dependent uptakes of adenosine (consistent with its concentrative uptake) and guanosine, rendering neuromodulator uptake independent of nucleoside metabolism. Astrocytes are accordingly well suited for both intense nucleoside metabolism and metabolism-independent uptake to terminate neuromodulator effects of adenosine and guanosine.

Adenosine↗

PubMed2004

[The expression and significance of costimulatory molecule in peripheral blood B lymphocytes in rheumatoid arthritis].

OBJECTIVE: To research the mechanisms of immune function disorder in the patients with rheumatoid arthritis (RA). METHODS: Monoclonal antibodies against CD(80), CD(86), CD(40) were used for flow cytometry and expression of costimulatory molecule CD(80), CD(86), CD(40) on peripheral blood B lymphocytes was studied in patients with RA, and healthy human were used as control groups. We also used enzyme linked immunosorbent assay to detect the cytokines level of Th1 cell including interleukin (IL)-2, interferon-gamma and those of Th2 cell including IL-6, IL-10. These samples are serum and synovial fluid of patients with RA, respectively. RESULTS: Compared with control group, the expression of CD(86) on peripheral blood B lymphocytes in patients with RA was obviously decreased (P < 0.01), the expression of CD(40) was also significantly increased (P < 0.05). No statistically significant differences in CD(80) positive peripheral blood B lymphocytes between RA group and control group were observed. Comparing with control group, the level of IL-2 and interferon-gamma in serum and synovial fluid of patients with RA are obviously increase (P < 0.01 or P < 0.05). While, the level of IL-6 and IL-10 are decrease (P < 0.01 or P < 0.05). CONCLUSIONS: The disorder expression of costimulatory molecule CD(86), CD(40) on peripheral blood B lymphocytes may be associated closely with the imbalance of Th1/Th2 cytokines level in patients with RA. These will give us a new idea on the therapeutic strategy of RA.

Adult↗

PubMed2004

[Establishing a new genotyping method of hepatitis B virus by polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) to analysis on S region and its application].

OBJECTIVE: To establish a new polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method of genotyping HBV using Mbo I, BsTN I, BsmA I, Hpa II and investigate the relationship between genotype and clinical spectrum of hepatitis B. METHODS: 124 full-genomic HBV sequences and 13 S-genomic sequences were analyzed, genotype specific regions were identified by the restriction enzymes Mbo I, BsTN I, BsmA I, Hpa II. And 176 samples from different kinds of hepatitis B were genotyped by this method. Five samples had been randomly selected and directly sequenced their S gene, to assess the accuracy. RESULTS: In 176 serum samples of patients with hepatitis B from Guizhou area, genotype B and C were found in 56.8% and 43.2% respectively. The proportions of genotype B and C in ASC were 40.0% and 15.7% (chi-square = 12.16, P < 0.005); and they were 31.6% and 14.0% in CHB (chi-square = 7.88, P < 0.005). CONCLUSION: Genotyping HBV, based on S gene RFLP seems to be highly sensitive, differential and accurate and could be used in large-scale surveys. HBV genotype B and C are existed in Guizhou area.

Genotype↗

PubMed2004

[Distribution of hepatitis B virus genotype among population of Dong, Miao minority and Han in Guizhou].

OBJECTIVE: To study the distribution of hepatitis B virus (HBV) genotype in population of Dong, Miao minority and Han in Guizhou. METHODS: S region nucleotides were compared in 127 strains whole sequence of HBV and three restriction enzymes which can be used for genotyping were found by DNA software analysis system. The partial gene fragment of HBV S region was amplified by nested polymerase chain reaction (nPCR). The products were digested with Mbo I, BstN I or BsmA I and subjected to electrophoresis on agarose gel, respectively. The patterns of restriction fragment length polymorphism (RFLP) were analysed. The genotypes were determined by nPCR-RFLP in 166 asymptomatic HBV carriers (ASC), including 48 Dong minority, 52 Miao minority and 66 Han subjects. Some of the ASC were also analysed by direct sequencing of PCR products. RESULTS: The nPCR-RFLP method was simple and accurate. Of the 166 ASC, 138 (83.13%) were genotype B, and 28 (16.87%) were genotype C. Of the 48 Dong minority subjects, 47 (97.2%) were genotype B and 1 (2.08%) was type C. Of the 52 Miao minority subjects, 49 (94.23%) were genotype B and 3 (5.77%) were genotype C. Of the 66 Han subjects, 42 (63.64%) were genotype B and 24 (36.36%) were genotype C. There was a statistical significance in the distribution of genotype C between Dong, Miao minority and Han (7.85% vs 36.36% P less than 0.005). CONCLUSION: Genotype B and C exist in Guizhou and genotype B is the major genotype. Genotype C is found more frequently in Han than in Dong and Miao minority.

Adolescent↗

PubMed2003

Alpha-adrenergic stimulation of ERK phosphorylation in astrocytes is alpha(2)-specific and may be mediated by transactivation.

The highly specific alpha(2)-adrenergic agonist, dexmedetomidine, has hypnotic-sedative, anesthetic-sparing and analgesic effects, and it protects neurons against ischemia. The alpha(1)-adrenergic agonist, phenylephrine, does not share dexmedetomidine's pharmacological properties, although both dexmedetomidine and phenylephrine increase free cytosolic Ca(2+) ([Ca(2+)](i)) in astrocytes, and most of dexmedetomidine's actions in the brain are exerted on postjunctional receptors. alpha(2)-Adrenergic receptors are abundant on astrocytes. Dexmedetomidine-mediated 'down-streamn' signal transduction was therefore investigated in primary cultures of mouse astrocytes and contrasted with that of phenylephrine. The cultures were incubated with dexmedetomidine concentrations known to be pharmacologically active and to act specifically on alpha(2)-adrenergic receptors (25-100 nM). ERK(1/2) phosphorylation was measured using specific antibodies. Peak increases of ERK(1/2) phosphorylation occurred at 50 nM dexmedetomidine, with less effect at higher concentrations. Phenylephrine caused ERK phosphorylation only at a concentration high enough to exert non subtype-specific effects (10 microM), and this effect was counteracted by the alpha(2)-adrenergic antagonist atipamezole. The phosphorylation of ERK was reduced by tyrphostin AG1478, an inhibitor of phosphorylation of the epidermal growth factor receptor (EGFR), and by heparin, which neutralizes heparin-binding epithelial growth factor (HB-EGF), suggesting the involvement of a transactivation process, in which alpha(2)-adrenergic stimulation leads to proteolytic shedding of HB-EGF (and perhaps other EGFR agonists) from transmembrane-spanning precursors.

Adrenergic alpha-2 Receptor Agonists↗

PubMed2002

Amobarbital inhibits K(+)-stimulated glucose oxidation in cerebellar granule neurons by two mechanisms.

The study aimed at determining mechanism(s) by which amobarbital (amytal) suppresses glucose oxidation in cerebellar granule neurons in primary cultures, a glutamatergic preparation. When challenged with a depolarizing K(+) concentration (55 mM), the cells doubled their rate of glucose oxidation (production of 14CO(2) from U-[14C]glucose) and glycolysis (lactate accumulation). At normal K(+) concentration, amobarbital reduced 14CO(2) production with half-maximum effect at 0.5-1 mM; at 55 mM K(+), the inhibition was more potent, with more than half of the K(+)-induced stimulation abolished at 50 microM. Dixon plot analysis showed a single inhibitory mechanism at 5.4 mM K(+), but at 55 mM K(+), two kinetically different mechanisms could be distinguished. A more pronounced compensatory amobarbital-induced increase in glycolysis at 5.4 than at 55 mM K(+) suggested that amobarbital in addition to its inhibition of mitochondrial respiration inhibited K(+)-induced increase in energy demand, probably by its known suppression of stimulated glutamate release.

Amobarbital↗

PubMed2002

Up-regulation of 5-HT2B receptor density and receptor-mediated glycogenolysis in mouse astrocytes by long-term fluoxetine administration.

The effects were studied of short-term (1 week) versus long-term (2-3 weeks) fluoxetine treatment of primary cultures of mouse astrocytes, differentiated by treatment with dibutyryl cyclic AMP. From previous experiments it is known that acute treatment with fluoxetine stimulates glycogenolysis and increases free cytosolic Ca2+ concentration ([Ca2+]i]) in these cultures, whereas short-term (one week) treatment with 10 microM down-regulates the effects on glycogen and [Ca2+]i, when fluoxetine administration is renewed (or when serotonin is administered). Moreover, antagonist studies have shown that these responses are evoked by activation of a 5-HT2, receptor that is different from the 5-HT2A receptor and therefore at that time tentatively were interpreted as being exerted on 5-HT2C receptors. In the present study the cultures were found by RT-PCR to express mRNA for 5-HT2A and 5-HT2B receptors, but not for the 5-HT2C receptor, identifying the 5-HT2 receptor activated by fluoxetine as the 5-HT2B receptor, the most recently cloned 5-Ht2 receptor and a 5-HT receptor known to be more abundant in human, than in rodent, brain. Both short-term and long-term treatment with fluoxetine increased the specific binding of [3H]mesulergine, a ligand for alL three 5-HT2 receptors. Long-term treatment with fluoxetine caused an agonist-induced up-regulation of the glycogenolytic response to renewed administration of fluoxetine, whereas short-term treatment abolished the fluoxetine-induced hydrolysis of glycogen. Thus, during a treatment period similar to that required for fluoxetine's clinical response to occur, 5-HT2B-mediated effects are initially down-regulated and subsequently up-regulated.

Animals↗