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Biomedical subjects

Jun Li

Publications and source records attributed to Jun Li.

At least 307 records · Page 17Linked to original sources
PubMed2005

Pharmacokinetics and tissue distribution of 5-fluorouracil encapsulated by galactosylceramide liposomes in mice.

AIM: To study the pharmacokinetics and tissue distribution of 5-fluorouracil encapsulated by galactosylceramide liposomes (5-Fu-GCL) in mice. METHODS: The concentration of 5-fluorouracil (5-Fu) in serum was detected by high performance liquid chromatography after 5-Fu-GCL (80, 40, 20 mg/kg) and free 5-Fu (40 mg/kg) were injected intravenously into mice. The tissue distribution of 5-Fu-GCL (40 mg/kg) and free 5-Fu (40 mg/kg) was investigated, and concentration-time profile of the two preparations in the liver were studied. Data were analyzed by 3p97 program. RESULTS: Serum concentration-time curves of 5-Fu-GCL and free 5-Fu conformed to one compartment model of first order absorption. 5-Fu-GCL at 80, 40, and 20 mg/kg had T(1/2Ke) of 25.8+/-4.2, 27.3+/-4.4, and 28.2+/-5.6 min; C0 of 24.9+/-4.9, 17.7+/-3.6, and 11.5+/-2.7 mg/L; and AUC of 990.0+/-45.2,622.5+/-38.3, and 340.4+/-25.6 mg x min x L(-1), respectively. In contrast free 5-Fu at 40 kg/mg had T(1/2Ke) of 15.8+/-2.2 min, C0 of 35.8+/-6.2 mg/L, AUC of 639.0+/-35.9 mg x min x L(-1). The tissue distribution of 5-Fu-GCL in the liver and immune organs was significantly increased, while in heart and kidney it was remarkably decreased. The AUC of 5-Fu-GCL in the liver was 3 times higher than that of free 5-Fu. CONCLUSION: The pharmacokinetics and tissue distribution of 5-Fu-GCL appears to be linear-related and dose-dependent, and exhibits sustained-release and hepatic target characteristics.

Animals↗
PubMed2005

Optimized interstitial PDT prostate treatment planning with the Cimmino feasibility algorithm.

The primary aim of this study was to determine whether optimized photodynamic therapy (PDT) treatment planning (seeking optimized positions, lengths, and strengths of the light sources to satisfy a given dose prescription) can improve dose coverage to the prostate and the sparing of critical organs relative to what can be achieved by the standard PDT plan. The Cimmino algorithm and search procedures based on that algorithm were tested for this purpose. A phase I motexafin lutetium (MLu)-mediated photodynamic therapy protocol is ongoing at the University of Pennsylvania. PDT for the prostate is performed with cylindrical diffusing fibers of various lengths inserted perpendicular to a base plate to obtain longitudinal coverage by a matrix of parallel catheters. The standard plan for the protocol uses sources of equal strength with equal spaced (1-cm) loading. Uniform optical properties were assumed. Our algorithms produce plans that cover the prostate and spare the urethra and rectum with less discrepancy from the dose prescription than the standard plan. The Cimmino feasibility algorithm is fast enough that changes to the treatment plan may be made in the operating room before and during PDT to optimize light delivery.

Algorithms↗
PubMed2005

luxS-dependent gene regulation in Escherichia coli K-12 revealed by genomic expression profiling.

The bacterial quorum-sensing autoinducer 2 (AI-2) has received intense interest because the gene for its synthase, luxS, is common among a large number of bacterial species. We have identified luxS-controlled genes in Escherichia coli under two different growth conditions using DNA microarrays. Twenty-three genes were affected by luxS deletion in the presence of glucose, and 63 genes were influenced by luxS deletion in the absence of glucose. Minimal overlap among these gene sets suggests the role of luxS is condition dependent. Under the latter condition, the metE gene, the lsrACDBFG operon, and the flanking genes of the lsr operon (lsrR, lsrK, tam, and yneE) were among the most significantly induced genes by luxS. The E. coli lsr operon includes an additional gene, tam, encoding an S-adenosyl-l-methionine-dependent methyltransferase. Also, lsrR and lsrK belong to the same operon, lsrRK, which is positively regulated by the cyclic AMP receptor protein and negatively regulated by LsrR. lsrK is additionally transcribed by a promoter between lsrR and lsrK. Deletion of luxS was also shown to affect genes involved in methionine biosynthesis, methyl transfer reactions, iron uptake, and utilization of carbon. It was surprising, however, that so few genes were affected by luxS deletion in this E. coli K-12 strain under these conditions. Most of the highly induced genes are related to AI-2 production and transport. These data are consistent with the function of LuxS as an important metabolic enzyme but appear not to support the role of AI-2 as a true signal molecule for E. coli W3110 under the investigated conditions.

Adaptation, Psychological↗
PubMed2005

Lignan and neolignan derivatives from Magnolia denudata.

A new tricyclo[4.2.0.0(2,8)]octane-type neolignan, 6-allyl-7-(3,4-dimethoxyphenyl)- 2,3-dimethoxy-8-methyl-tricyclo[4.2.0.0(2,8)]oct-3-en-5-one, together with 15 known lignan and neolignan derivatives have been isolated from the flower buds of Magnolia denudata DESR. and the structures of these compounds have been elucidated based on the 1H- and 13C-NMR spectra and two-dimensional NMR methods such as HMBC, HMQC, and NOESY.

China↗
PubMed2005

Carbon nanotubes and nanowires for biological sensing.

This chapter reviews the recent development in biological sensing using nanotechnologies based on carbon nanotubes and various nanowires. These 1D materials have shown unique properties that are efficient in interacting with biomolecules of similar dimensions, i.e., on a nanometer scale. Various aspects including synthesis, materials properties, device fabrication, biofunctionalization, and biological sensing applications of such materials are reviewed. The potential of such integrated nanobiosensors in providing ultrahigh sensitivity, fast response, and high-degree multiplex detection, yet with minimum sample requirements is demonstrated. This chapter is intended to provide comprehensive updated information for people from a variety of backgrounds but with common interests in the fast-moving interdisciplinary field of nanobiotechnology.

Biosensing Techniques↗
PubMed2005

SAK, a new polo-like kinase, is transcriptionally repressed by p53 and induces apoptosis upon RNAi silencing.

Chip profiling of a p53 temperature-sensitive tumor model identified SAK (Snk/Plk-akin kinase), encoding a new member of polo-like kinases (PLKs), as a gene strongly repressed by wild-type p53. Further characterization revealed that SAK expression was downregulated by wild-type p53 in several tumor cell models. Computer search of a 1.7-kb SAK promoter sequence revealed three putative p53 binding sites, but p53 failed to bind to any of these sites, indicating that SAK repression by p53 was not through a direct p53 binding to the promoter. Transcriptional analysis with luciferase reporters driven by SAK promoter deletion fragments identified SP-1 and CREB binding sites, which together conferred a two-fold SAK repression by p53. However, the repression was not reversed by cotransfection of SP-1 or CREB, suggesting a lack of interference between p53 and SP-1 or CREB. Significantly, p53-mediated SAK repression was largely reversed in a dose-dependent manner by Trichostatin A, a potent histone deacetylase (HDAC) inhibitor, suggesting an involvement of HDAC transcription repressors in SAK repression by p53. Biologically, SAK RNA interference (RNAi) silencing induced apoptosis, whereas SAK overexpression attenuated p53-induced apoptosis. Thus, SAK repression by p53 is likely mediated through the recruitment of HDAC repressors, and SAK repression contributes to p53-induced apoptosis.

Amino Acid Sequence↗
PubMed2005

Modeling water and carbon fluxes above summer maize field in North China Plain with back-propagation neural networks.

In this work, datasets of water and carbon fluxes measured with eddy covariance technique above a summer maize field in the North China Plain were simulated with artificial neural networks (ANNs) to explore the fluxes responses to local environmental variables. The results showed that photosynthetically active radiation (PAR), vapor pressure deficit (VPD), air temperature (T) and leaf area index (LAI) were primary factors regulating both water vapor and carbon dioxide fluxes. Three-layer back-propagation neural networks (BP) could be applied to model fluxes exchange between cropland surface and atmosphere without using detailed physiological information or specific parameters of the plant.

Agriculture↗
PubMed2005

Application of least squares vector machines in modelling water vapor and carbon dioxide fluxes over a cropland.

Least squares support vector machines (LS-SVMs), a nonlinear kemel based machine was introduced to investigate the prospects of application of this approach in modelling water vapor and carbon dioxide fluxes above a summer maize field using the dataset obtained in the North China Plain with eddy covariance technique. The performances of the LS-SVMs were compared to the corresponding models obtained with radial basis function (RBF) neural networks. The results indicated the trained LS-SVMs with a radial basis function kernel had satisfactory performance in modelling surface fluxes; its excellent approximation and generalization property shed new light on the study on complex processes in ecosystem.

Agriculture↗
PubMed2005

Bench-scale evaluation of in situ bioremediation strategies for soil at a former manufactured gas plant site.

We examined the biodegradation and desorption of a set of 15 polycyclic aromatic hydrocarbon (PAH) compounds in coal tar-contaminated soil at a former manufactured gas plant site to evaluate the feasibility of in situ bioremediation. Experiments were conducted in well-mixed aerobic soil suspensions containing various additives over a 93- to 106-d period. In general, both biotransformation and desorption decreased with PAH ring size, becoming negligible for the six-ring PAH compounds. Biodegradation by indigenous microorganisms was strongly accelerated by addition of inorganic nutrients (N, P, K, and trace metals). The rates of biotransformation of PAH compounds by indigenous microorganisms in nutrient-amended flasks outpaced their maximum (i.e., chelate-enhanced) rates of desorption to an infinite sink (Tenax) in sterilized systems run in parallel, suggesting that indigenous organisms facilitated desorption. Biodegradation by indigenous organisms in nutrient-amended flasks appeared to be unaffected by the addition of a site-derived bacterial enrichment culture, resulting in approximately 100-fold higher aromatic dioxygenase levels, and by the addition of 0.01 M chelating agent (citrate or pyrophosphate), although such chelating agents greatly enhanced desorption in microbially inactivated flasks. The strong ability of nutrients to enhance degradation of the bioavailable PAHs indicates that their persistence for many decades at this site likely results from nutrient-limited natural biodegradation, and it also suggests that an effective strategy for their bioremediation could consist simply of adding inorganic nutrients.

Adsorption↗
PubMed2005

[Clinicopathologic features and prognostic factors of cervical lymph node metastasis in oral squamous cell carcinoma].

BACKGROUND & OBJECTIVE: The cervical lymphatic meta-static rate of oral squamous carcinoma is 50%-59%. The management of cervical lymphatic metastasis relates with prognosis of patients with oral squamous carcinoma. This study was to investigate the clinicopathologic features and prognosis factors of cervical lymph node metastasis in oral squamous cell carcinoma. METHODS: Clinicopathologic data of 191 patients with oral squamous cell carcinoma were retrospectively reviewed. The relationship between histopathologic factors and cervical lymph node metastasis was evaluated by univariate Chi(2) test. Cox regression model was used to analyze impacts of pathologic factors of cervical lymph nodes, such as metastatic status, size and number of positive neck nodes,levels of positive nodes, the lowest involved nodal level, on prognosis. RESULTS: The overall 5-year survival rate of the 191 patients was 48.7%. Univariate Chi(2) test confirmed that only depth of primary tumor infiltration correlated to cervical lymph node metastasis. Cox regression analysis revealed that clinical N stage, cervical lymphatic metastatic status, number of involved levels, and the lowest involved nodal level affected prognosis of patients, the most significant prognostic factors of cervical lymph node were clinical N stage, and the lowest involved nodal level. CONCLUSIONS: Cervical lymph node metastasis is a significant prognostic factor of oral squamous cell carcinoma. The identification of metastatic patterns of cervical lymph nodes, and the management targeting pathologic factors of cervical lymph node affecting survival are critical for improving the treatment effect on oral squamous cell carcinoma.

Adult↗
PubMed2005

Expression of polycythemia rubra vera-1 decreases the dependency of cells on growth factors for proliferation.

An increase in the level of polycythemia rubra vera -1 (PRV-1) mRNA has been reported in some myeloproliferative disorders. We have studied the effects of PRV-1 on cell proliferation and cell survival. In cell growth assays, the number of heterologous cells expressing PRV-1 increased faster than sham-transfected cells, a difference that was more pronounced in serum-free media. Even after 5 days of exposure to serum-free media, cells expressing PRV-1 continued to proliferate, whereas the control cells ceased to proliferate. We conclude that PRV-1 is a pro-proliferation molecule, and hypothesize that its overexpression may have a role in the pathogenesis of myeloproliferative disorders.

Animals↗
PubMed2005

[Association between dopamine beta hydroxylase gene and attention deficit hyperactivity disorder complicated with disruptive behavior disorder].

OBJECTIVE: Attention deficit hyperactivity disorder (ADHD), a common behavior disorder of childhood, is a highly heterogeneous disease frequently accompanied by various mental disorders, including disruptive behavior disorder (DBD). Studies show that children suffering from ADHD with DBD are at higher risk of antisocial personality, substance abuse, and social adaptations disorder at their adulthood. The dopamine beta hydroxylase (DbetaH) is the key enzyme to ADHD since it catalyzes the conversion of dopamine to norepinephrine, and dysfunction there of is believed to be one of the causes of the disorder. To explore the association between DBH gene and ADHD complicated with or without DBD, the authors analyzed the transmission of a novel polymorphism DBH -1021C-->T, which is found associated with plasma DbetaH activity, in ADHD nuclear families using transmission disequilibrium test (TDT). METHODS: Consensus diagnoses were based on the DSM-IV. The samples included those from 292 Chinese Han nuclear families with ADHD probands. Genotypes of DBH -1021C-->T polymorphism were determined by PCR amplification, endonuclease digesting and electrophoresis. The transmission of DBH -1021C-->T polymorphism in ADHD nuclear families with or without DBD was analyzed by TDT. RESULTS: The results showed that there was transmission disequilibrium between DBH-1021C-->T polymorphism and ADHD with or without DBD. In ADHD comorbid with DBD, T allele was preferentially transmitted (P < 0.05); and in ADHD without DBD, so was the C allele (P < 0.05). Among the three subtypes of ADHD, only ADHD-C subtype with DBD had an increased transmission of T allele (P < 0.05). CONCLUSION: There is an association between DBH gene and ADHD comorbid with or without DBD, but the preferential transmission alleles are different. The low activity T allele is increased to transmit in ADHD with DBD, while the high activity C allele is preferentially transmitted in ADHD without DBD. The results support the proposition that the genetic mechanism is different between ADHD comorbid with or without DBD. We also found that only ADHD-C subtype with DBD is associated with DBH -1021C-->T polymorphism in three subtypes of ADHD, which may suggest that there is a more intense relationship between DBD and ADHD-C subtype.

Alleles↗
PubMed2005

[Complications of transcatheter interventional occlusion of ventricular septal defects].

OBJECTIVE: To investigate the complications and their prevention in patients with perimembranous ventricular septal defect (VSD) experiencing transcatheter interventional occlusion. METHODS: From July, 2002 to May, 2004, totally 262 (138 males, 124 females) perimembranous VSD patients underwent transcatheter interventional occlusion in the department. The age ranged from 2 to 18 years (mean 9.3 +/- 5.8 years), and the body weight ranged from 11.0 to 65.0 kg (mean 30.5 kg). The implanted occluder with imported Amplatzer eccentric perimembranous VSD occluder, domestic double-disk, domestic eccentric perimembranous VSD and PDA occluder were attempted in 12, 212, 28 and 6 cases, respectively. Among them, 3 cases were complicated with ductus arteriosus, 4 with atrial septal defects and 1 with patent ductus arteriosus plus atrial septal defect. The associated defects were treated with other occluders at the same time. RESULTS: The diameters of VSD measured by transthoracic echocardiography before occlusion and by ventriculography during the procedure ranged from 2.7 to 13 mm (mean 6.5 mm) and from 1.3 to 14.0 mm (mean 6.8 mm), respectively. The defects in 256 cases (97.7%) were successfully occluded. The implant occluder was from 4 to 16 mm in size. Serious complications occurred in 8 cases (3.1%), including 5 cases of high degree atrioventricular block (AVB) (2.0%), 2 cases of hemolysis (0.8%) and 1 case of displacement of the occluder (0.4%). Amongst 5 cases of high degree AVB, permanent pacemaker was implanted only in 1 case due to high degree AVB 50 days after treatment, whereas the others all recovered. Two cases of hemolysis were completely recovered. One case of occluder displacement was emergently transferred to cardiac surgery. Other complications included residual shunt during 6 month follow-up in 1 case (0.4%), minor aortic regurgitation in 5 cases (2.0%), minor tricuspid regurgitation during 6 month follow-up in 4 cases (1.6%), and accelerated idioventricular rhythm or accelerated atrio-ventricular junctional tachycardia combined with atrioventricular interference-dissociation by ECG in 75 cases (29%) but they recovered after 3 - 5 days of corticosteroid treatment. Forty-one cases (16%) complicated with complete or incomplete right bundle branch block, of whom 50% recovered during follow-up. Still, there were 4 cases (1.6%) who were complicated with complete left bundle branch block but were all recovered during follow-up and 26 cases (10%) who were complicated with intraventricular block. There were no Significant difference in complications between cases who accepted imported Amplatzer occluders and domestic occluders. CONCLUSION: Transcatheter interventional occlusion is a safe, effective and ideal method with low incidence of serious complications for perimembranous VSD. Long term follow-up and clinical research should be carried out to improve the level of VSD interventional therapy.

Adolescent↗
PubMed2005

[Evaluation of mastication function after three-dimensional maxillary reconstruction].

OBJECTIVE: To evaluate the mastication function of the patient whose maxilla was reconstructed with individual titanium mesh and Chinese flap or combined with fibular flap. The superiority of this method on maxillary functional reconstruction was testified. METHODS: Since March of 2001, 10 cases of maxillary defect were reconstructed with individual titanium mesh and Chinese flap or combined with fibular flap, and routine removal partial dentures were fixed after 3 - 6 months postoperatively. Assessment of occlusal force was proceeded by T-Scan II system (Tekscan company, USA). RESULTS: The occlusal force analysis results indicated the asymmetry index of bite force and asymmetry index of occlusal contact area differed significantly between preoperation and postopertion (P < 0.05). The recovery rate of total occlusal force was between 27.05%-74.06%, and the average was 50.15%. CONCLUSION: This new three-dimensional maxillary functional reconstruction method had a satisfactory recovery in both of contour and function recently, especially restored the mastication function effectively.

Humans↗
PubMed2005

[Acid mining drainage impacts on the separation between iron and manganese in sediments of the Aha Lake, Guizhou Province].

Since the Aha Lake, located in Guizhou Province, China, was enlarged in 1982, a great amount of iron and manganese were input into it owing to the uninterrupted pollution from acidic mining drainage of coal mines (AMD). The results show that dissolved Fe2+ and Mn2+, mainly from AMD, were markedly separated each other as water flowed from inlet to downstream. The Aha lake water, with the average pH equal to 7.28, was not acidified just because the lake is developed in the karst area and people continuously put lime in it in recent years. Fe2 + and Mn2 + deposit in the different locations in lake because of the difference of oxidizing rate between Fe2+ and Mn2+ during water flowing from inlet to downstream, and also forming the horizontal separation along the lake water flowing direction. Manganese tends to be obviously enriched in the upper of sediment in lake's deep locations, presenting the remarkable separation with iron in the vertical section. After normalized by Ti content in sediment, it is obvious that the remarkable separation between iron and manganese corresponds with the enlargement of lake in 1982. As shown in the concentration profile of pore water in sediment, iron was remobilized weakly while manganese reduction mainly happens in the upper of sediment, indicating its strong remobilization. Based on the studies, a mechanism for environment and fractionation of Fe2+ /Mn2 + during water flowing in the lake was also demonstrated.

China↗