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Biomedical subjects

Jun Li

Publications and source records attributed to Jun Li.

At least 73 records · Page 4Linked to original sources
PubMed2006

Pb12 2-: plumbaspherene.

Although Si or Ge is not known to form empty cage clusters such as the fullerenes, we recently found a unique 12-atom icosahedral tin cluster, Sn12 2- (stannaspherene). Here we report photoelectron spectroscopy and theoretical evidence that Pb12 2- is also a highly stable icosahedral cage cluster and bonded by four delocalized radial pi bonds and nine delocalized on-sphere sigma bonds from the 6p orbitals of the Pb atoms. Following Sn12 2-, we coin a name, plumbaspherene, for the highly stable and nearly spherical Pb12 2- cluster, which is expected to be stable in solution and the solid state. Plumbaspherene has a diameter of approximately 6.3 A with an empty interior volume large enough to host most transition metal atoms, affording a new class of endohedral clusters.

Journal Article↗
PubMed2006

A new method for detecting human recombination hotspots and its applications to the HapMap ENCODE data.

Computational detection of recombination hotspots from population polymorphism data is important both for understanding the nature of recombination and for applications such as association studies. We propose a new method for this task based on a multiple-hotspot model and an (approximate) log-likelihood ratio test. A truncated, weighted pairwise log-likelihood is introduced and applied to the calculation of the log-likelihood ratio, and a forward-selection procedure is adopted to search for the optimal hotspot predictions. The method shows a relatively high power with a low false-positive rate in detecting multiple hotspots in simulation data and has a performance comparable to the best results of leading computational methods in experimental data for which recombination hotspots have been characterized by sperm-typing experiments. The method can be applied to both phased and unphased data directly, with a very fast computational speed. We applied the method to the 10 500-kb regions of the HapMap ENCODE data and found 172 hotspots among the three populations, with average hotspot width of 2.4 kb. By comparisons with the simulation data, we found some evidence that hotspots are not all identical across populations. The correlations between detected hotspots and several genomic characteristics were examined. In particular, we observed that DNaseI-hypersensitive sites are enriched in hotspots, suggesting the existence of human beta hotspots similar to those found in yeast.

Base Composition↗
PubMed2006

Immunomodulation by interleukin-4 suppresses matrix metalloproteinases and improves cardiac function in murine myocarditis.

Immune response is critically involved in determining the course of viral myocarditis and immunomodulation. Different cytokines may have either deleterious or protective effects. Following acute Coxsackievirus B3 infection, intramyocardial inflammation is associated with altered myocardial matrix metalloproteinase (MMP) expression and left ventricular dysfunction. In this study, we evaluated the effect of exogenous interleukin-4 treatment on myocardial inflammation, MMPs and left ventricular function in Coxsackievirus B3-induced acute murine myocarditis. Eight-week-old inbred male BALB/c (H-2d) mice (The Jackson Laboratory, Bar Harbor, Maine, USA) were used. Myocardial inflammation was measured by immunohistochemical detection of CD3(+)-, CD8a(+)-T-lymphocytes, and CD11b+ macrophages. In situ hybridization was used to detect enteroviral genome in the myocardium. Semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) was employed to detect cytokine and MMP mRNA. MMP activity was quantified by zymography analysis. Detection of myocytolysis was performed by Luxol fast blue staining. In the early acute phase, in comparison to infected mice without treatment, interleukin-4 administration (200 ng daily) reduced intramyocardial inflammation (CD3+ lymphocytes: 55.3+/-7.0 vs. 72.1+/-13.7 cells/mm2, P < 0.05; CD8a+ lymphocytes: 31.7+/-3.6 vs. 64.2+/-7.7 cells/mm2, P < 0.05; CD11b+ macrophages: 5.1+/-2.3 vs. 13.2+/-2.5 cells/mm2, P < 0.05). It also down-regulated interleukin-2 (IL) (1.7-fold, P < 0.001) but increased transforming growth factor-beta1 (TGF) (1.5-fold, P < 0.001) and IL-4 (1.4-fold, P < 0.001). IL-4 suppressed MMP-2/-3/-9 transcription and activity. These biochemical alterations were accompanied by a significant improvement of left ventricular function as assessed by Milar tip catheter (left ventricular endsystolic pressure, 1.3-fold, P < 0.01; dP/dt max, 1.5-fold, P < 0.01). Immunomodulation by exogenous IL-4 treatment may lead to an anti-inflammatory effect with the inhibition of Th1 cell phenotypic response, which may further mediate the down-regulation of MMPs. A significant suppression of MMPs may mainly contribute to an improvement of left ventricular dysfunction in acute murine CVB3-induced myocarditis.

Animals↗
PubMed2006

Vaccination of dogs against Echinococcus granulosus, the cause of cystic hydatid disease in humans.

Dogs are pivotal in Echinococcus granulosus transmission to humans, and dog vaccination provides a very practical and cost-effective prevention strategy. We vaccinated dogs with soluble native proteins isolated from protoscoleces of E. granulosus and induced significant suppression of worm growth and egg production. Accordingly, we tested for vaccine efficacy using recombinant proteins derived from a developmentally regulated gene family (egM) specifically expressed in mature adult E. granulosus worms. Three egM genes--egM4, egM9, and egM123--were subcloned into an expression vector that expressed the molecules as soluble glutathione S-transferase (GST) fusion proteins in Escherichia coli. The 3 fusion proteins were purified for dog vaccination trials (3 doses of 80 microg/protein/dog) in which the dogs were challenged and then necropsied 45 days after infection. Compared with worms in the control dogs that received GST, the 3 recombinant proteins induced a very high level of protection (97%-100%) in terms of suppression of worm growth and, especially, of egg development and embryogenesis. We have thus shown that vaccination of the dog host against E. granulosus is feasible when recombinant proteins are used. Because the egg stage is crucial in the echinococcal life cycle, successful suppression of egg development by vaccination would halt transmission to intermediate hosts, thereby effecting long-term control.

Animals↗
PubMed2006

A gradient HPLC method for the quality control of chlorogenic acid, linarin and luteolin in Flos Chrysanthemi Indici suppository.

The Flos Chrysanthemi Indici suppository, a famous traditional Chinese medicine, is marketed for the treatment of prostatitis and chronic pelvic inflammation. A simple, relatively rapid and accurate high-performance liquid chromatographic (HPLC) method was applied to the simultaneous determination of chlorogenic acid, linarin and luteolin in Flos Chrysanthemi Indici suppository. The good separation was achieved on a Hypersil ODS column by a gradient elution using the mixture of acetonitrile and aqueous 1.0% acetic acid as mobile phase within 23 min. The method was validated for three active phenolic compounds with the relative standard deviations (R.S.D.) of intra- and inter-day precision below 3.0%, and the detection limits (S/N=3) of chlorogenic acid, linarin and luteolin were 0.32, 0.08 and 0.05 microg ml(-1), respectively. This assay was successfully applied to the determination of three active phenolic compounds in Flos Chrysanthemi Indici suppository samples with the quantitative recoveries in the range of 94.7-101.8%. The results indicate that the developed HPLC method can be readily utilized as a quality control method for Flos Chrysanthemi Indici suppository and its related traditional Chinese medicinal preparations.

Acetic Acid↗
PubMed2006

A Chinese herbal decoction, Danggui Buxue Tang, prepared from Radix Astragali and Radix Angelicae Sinensis stimulates the immune responses.

Danggui Buxue Tang (DBT), a Chinese medicinal decoction that is used commonly for treating women's ailments, contains Radix Astragali and Radix Angelicae Sinensis. The ratio of Radix Astragali and Radix Angelicae Sinensis used in DBT should be 5 : 1 as described in China in 1247 A.D. In order to verify the efficacy of this ancient formulation in stimulating the immune responses, DBT prepared from different drug ratios was applied onto cultured T-lymphocytes and macrophages. In cultured T-lymphocytes, DBT induced markedly cell proliferation, secretion of interleukin-2 and phosphorylation of extracellular signal-regulated kinase. In addition, the phagocytosis of cultured macrophages was increased by DBT treatment. The immunomodulatory effects of DBT were revealed to be the strongest in the extract derived from the drug ratio of 5 : 1. The current results verified that the ancient formulation of DBT has been optimized in stimulating immune responses.

Angelica sinensis↗
PubMed2006

Characterization and identification of the candidate gene of rice thermo-sensitive genic male sterile gene tms5 by mapping.

Previous research has demonstrated that the thermo-sensitive genic male-sterile (TGMS) gene in rice was regulated by temperature. TGMS rice is important to hybrid rice production because the application of the TGMS system in two-line breeding is cost-effective, simple, efficient and overcomes the limitations of the cytoplasmic male sterility (CMS) system. AnnongS is the first discovered and deeply studied TGMS rice line in China. Previous studies have suggested that AnnongS-1 and Y58S, two derivative TGMS lines of AnnongS, were both controlled by a single recessive gene named tms5, which was genetically mapped on chromosome 2. In the current study, three populations (AnnongS-1 x Nanjing11, Y58S x Q611, and Y58S x Guanghui122) were developed to investigate the tms5 gene molecular map. Analysis of recombination events of sterile samples, utilizing 125 probes covering the tms5 region, suggested that the tms5 gene was physically mapped to a 19 kb DNA fragment between two markers, 4039-1 and 4039-2, located on the BAC clone AP004039. Following the construction of a physical map between the two markers, ONAC023, a member of the NAC (NAM-ATAF-CUC-related) gene family, was identified as the candidate of the tms5 gene.

Chromosome Mapping↗
PubMed2006

Arylaminoethyl carbamates as a novel series of potent and selective cathepsin S inhibitors.

We report a novel series of noncovalent inhibitors of cathepsin S. The synthesis of the peptidomimetic scaffold is described and structure-activity relationships of P3, P1, and P1' subunits are discussed. Lead optimization to a non-peptidic scaffold has resulted in a new class of potent, highly selective, and orally bioavailable cathepsin S inhibitors.

Administration, Oral↗
PubMed2006

Synthesis and SAR of arylaminoethyl amides as noncovalent inhibitors of cathepsin S: P3 cyclic ethers.

The synthesis and structure-activity relationship of a series of arylaminoethyl amide cathepsin S inhibitors are reported. Optimization of P3 and P2 groups to improve overall physicochemical properties resulted in significant improvements in oral bioavailability over early lead compounds. An X-ray structure of compound 37 bound to the active site of cathepsin S is also reported.

Administration, Oral↗
PubMed2006

A systematic density functional theory study of the C-N bond cleavage of methylamine on metals.

The C-N bond cleavage for the relative large molecule of methylamine on Cu(1111), Ag(111), Au(111), Ni(111), Rh(111), Pd(111), Pt(111), and Mo(100) has been systemically studied using the DFT-GGA method; the reaction energy changes and the activation energies were obtained. The calculated results show that the activation energy of C-N bond cleavage decreases as the metal element goes up and to the left across the periodic table, which is in general agreement with the experimental observation. Moreover, it was found that the steric effect should be considered for the metals with high activity and small radius such as Ni, which is much different from the case for the small molecule decomposition in which the steric effect may be ignored. The linear relationships between the activation energies and electronic properties (d-band center) are presented. It is expected that such a rule can be used to predict the reactivity of metal for other dissociative adsorption systems.

Journal Article↗
PubMed2006

No observable relationship between the ACE gene insertion/deletion polymorphism and psychometric IQ and psychomotor ability in Chinese children.

The primary aim of this study was to investigate the impact of the angiotensin I-converting enzyme gene (ACE) on general cognitive ability, specific cognitive ability and psychomotor function in Chinese children. In total, 450 children completed both C-WISC tests and ACE I/D genotyping. Of these, 320 children were examined using psychomotor tests. The quantitative traits of psychometric IQ and psychomotor abilities were calculated to determine whether there were any significant differences related to their ACE genotypes on the basis of an analysis of variance. F test results showed no significant differences with regard to any aspect of intelligence or psychomotor performance relative to the various ACE I/D genotypes (all p > 0.05). Our study suggests that ACE I/D do not have a measurable impact on any aspects of IQ or psychomotor ability and that psychomotor ability correlates well with IQ in Chinese children.

Asian People↗
PubMed2006

[Effect of thymectomy in treatment of myasthenia gravis: analysis of 67 cases].

OBJECTIVE: To evaluate the clinical effects of thymectomy in treatment of myasthenia gravis: (MG). METHODS: The clinical data of 67 patients, 29 males and 38 females, aged 10.5 - 68, who underwent thymectomy were analyzed. RESULTS: According to the Monden's standard the overall effective rate of thymectomy was 71.6%. The remission rate was 32.8% (22/6), the improvement rate was 38.8% (26/67), 14 patients showed no change (20.9%), and deterioration was seen in 5 patients (7.5%). CONCLUSION: An effective method to treat MG, thymectomy should be performed on most of the MG patients early and actively.

Adolescent↗
PubMed2006

[Effects of vitamin K3 on the contractile activity of the colonic smooth muscles of guinea pig through the calcium activated potassium channel].

OBJECTIVE: To study the mechanism of relaxation of gastrointestinal smooth muscles by vitamin K(3). METHODS: Stripes of proximal colon were collected from guinea pigs. Suspension of single cells was created from these stripes. TD-112S transducer was used to measure the contraction of the stripes stimulated by vitamin K(3) of the concentrations of 40, 100, 400, and 800 micromol/L respectively. The Ca(2+)-activated K(+) current [IK(Ca)] of the cytomembrane of the colon smooth muscle was recorded with an EPC 10 amplifier under conventional whole cell patterns. RESULTS: The contraction frequencies of the muscle stripes stimulated by vitamin K(3) of the concentrations of 40, 100, 400, and 800 micromol/L were 79% +/- 4%, 58% +/- 5%, 33% +/- 4%, and 12% +/- 3% respectively of that of the control group (all P < 0.01), and the contraction strength was reduced to 77% +/- 10%, 54% +/- 7%, 30% +/- 6%, and 11% +/- 4% respectively (all P < 0.01). The IK((Ca)) of the cytomembrane of the colon smooth muscle at the voltage of +60 mV was increased to 120% +/- 18%, 149% +/- 12%, 197% +/- 19%, and 223% +/- 14% respectively (all P < 0.01). CONCLUSION: Vitamin K(3) inhibits the contractile activity of the colonic muscle stripes and increases the IK(Ca) of single myocytes concentration-dependently. The mechanism is activation of the Ca(2+)-activated K(+) channel, thus promoting the potassium efflux.

Animals↗
PubMed2006

Study on warfarin plasma concentration and its correlation with international normalized ratio.

A sensitive high-performance liquid chromatographic (HPLC) method was developed for warfarin determination in plasma of patients who undertook cardiac valve replacement and were on anticoagulation with warfarin. The method described proved to be accurate, sensitive, easy to perform, reproducible and specific for plasma warfarin measurement with relative standard deviation (R.S.D.) of <5.27% for inter-day and <6.89% for intra-day. The assay was linear in warfarin concentration ranges of 0.12-3 microg/ml (r=0.9995) with mean recovery of 94.6%. The mean warfarin plasma concentration of 58 patients with heart valve replacement within 1 month of post operation was 567.6+/-122.3 ng/ml. The anticoagulant effect of the drug was monitored by international normalized ratio (INR). The correlation of warfarin dosage and concentration with INR was analysed, and the coefficients were 0.21, 0.1<p<0.2 and 0.30, 0.02<p<0.1, respectively. The correlation of warfarin dosage or concentration with INR is very poor, and hence in order to adjust the dosage more objectively and accurately, concentration monitoring is necessary and helpful for the patient management. It is needed especially when the ideal INR is difficult to target.

Anticoagulants↗
PubMed2006

Measurement of in-air output ratios using different miniphantom materials.

In-air output ratios, S(c), were measured using miniphantoms made of PMMA (thickness 2.4-24 g cm(-2)), graphite (1.8-26.5 g cm(-2)), copper (1.6-23.3 g cm(-2)) and lead (2.3-21.6 g cm(-2)), for collimator settings of 3 x 3 to 40 x 40 cm(2), and x-ray energies of 6 MV and 15 MV, respectively. The effects of the miniphantom on S(c) were quantified as correction factors as functions of collimator setting, material types and miniphantom thickness for each photon energy to correct the measured values. For miniphantoms with sufficient thickness to eliminate electron disequilibrium, the total correction factors can be expressed as multiplications of three factors: the attenuation correction factor, the mass energy absorption correction factor and the phantom scatter correction factor. This formalism implies that the collimator setting dependence of the correction factor is mainly caused by the energy spectrum shift. The narrow-beam attenuation coefficients in various phantom materials for different collimator settings were determined in narrow-beam geometries using a specially constructed collimator mounted on the tray holder of the accelerator. We have determined that the maximum total correction factor is approximately 1.01. For miniphantoms made of PMMA, graphite, copper and lead, at the miniphantom thickness of 10 g cm(-2), the maximum total correction factors are 1.002, 1.003, 1.005, 1.007, and 1.002, 1.003, 1.008 and 1.009 for 6 MV and 15 MV, respectively.

Air↗
PubMed2006

[Needlescopic thoracic sympathectomy for palmar hyperhidrosis].

OBJECTIVE: To evaluate the safety and efficacy of needlescopic thoracic sympathectomy for palmar hyperhidrosis. METHODS: From March 2004 to April 2005, 62 patients, including 23 men and 39 women with a mean age of 23 years (ranged from 12 to 53 years), underwent bilateral needlescopic thoracic sympathectomy. Among all the patients 8 cases had accompanied axillary hyperhidrosis. The degree of palmar sweating was moderate in 16 cases and severe in 46 cases. The sympathetic chain on the body of the second and third ribs in all patients was cauterized and divided; the chain on the fourth rib in those with axillary hyperhidrosis was also severed. Intraoperative changes in palmar temperature and blood flow were recorded. RESULTS: Sympathectomies were successful, and dry limbs were immediately achieved in all patients after surgery. There were no mortality or life-threatening complication, however 1 patient developed moderate pneumothorax which resolved soon after chest drainage. After all procedures, palmar blood perfusion increased significantly and mean palmar temperature elevated by 2.4 degrees C. The mean operative duration was 65 min, and the mean postoperative hospital stay was 1.2 days. No recurrence of palmar hyperhidrosis occurred after a mean follow-up of 6.3 months (ranged from 1 to 13 months). Compensatory sweating was found in 26 patients, but the symptoms were mostly tolerable and required no further treatment. CONCLUSION: Needlescopic thoracic sympathectomy is a safe and effective technique for palmar hyperhidrosis, which is less invasive than conventional video-assisted thoracic surgery.

Adolescent↗
PubMed2006

Enzyme catalysis: tool to make and break amygdalin hydrogelators from renewable resources: a delivery model for hydrophobic drugs.

We report a novel approach for the controlled delivery of an antiinflammatory, chemopreventive drug by an enzyme-triggered drug release mechanism via the degradation of encapsulated hydrogels. The hydro- and organogelators are synthesized in high yields from renewable resources by using regioselective enzyme catalysis, and a known chemopreventive and antiinflammatory drug, i.e., curcumin, is used for the model study. The release of the drug occurred at physiological temperature, and control of the drug release rate is achieved by manipulating the enzyme concentration and/or temperature. The byproducts formed after the gel degradation were characterized and clearly demonstrated the site specificity of degradation of the gelator by enzyme catalysis. The present approach could have applications in developing cost-effective controlled drug delivery vehicles from renewable resources, with a potential impact on pharmaceutical research and molecular design and delivery strategies.

Amygdalin↗