Biomedical subjects
Publications and source records attributed to Jian Liu.
beta-cyclodextrin immobilized on Pd nanoparticles was successfully employed as an efficient phase-transfer catalyst in aqueous biphasic hydrogenation reactions.
[reaction: see text] Practical asymmetric synthesis of aldehyde 2 and tetrazolyl sulfone 3 has allowed for their coupling via Julia olefination to generate 32 as a single product. This substance possesses the entire carbon backbone of the A-E substructure of pectenotoxin-2.
AIM: Human heparanase is an endo-D-glucuronidase that degrades heparan sulfate/heparin and has been implicated in a variety of biological processes. The objective was to investigate the expression of heparanase (Hps) and basic fibroblast growth factor (bFGF) and their relationship to neoangiogenesis and metastasis of human esophageal carcinoma. METHODS: Seventy-nine patients who had undergone esophageal resection for esophageal carcinoma without preoperative treatment were included in the present study. Immunohistochemistry was used to study the expression of Hps, bFGF and microvessel density (MVD) in 79 cases of esophageal carcinoma. bFGF and Hps were quantitatively detected with immunohistochemistry in 79 cases of human esophageal carcinoma and 19 cases of adjacent normal human esophageal carcinoma. Cd34 was used to explore the MVD as a marker of endothelial cells. RESULTS: Hps and bFGF expression in tumor tissue, being remarkably higher than that in normal esophageal tissue, were significantly correlated with clinicopathological features (depth of invasion, lymph-node metastasis and TNM stage) and MVD. CONCLUSION: The results of this study suggest that the coexpression of Hps and bFGF plays a key role in angiogenesis, invasion and metastasis of esophageal carcinoma. Hps and bFGF may serve as a predictor of progression in esophageal carcinoma. The expression of heparanase in esophageal carcinoma enhances growth, invasion, and angiogenesis of the tumor, and bFGF seems to be a potent antigenic factor for esophageal carcinoma.
Taurine/alpha-ketoglutarate (alphaKG) dioxygenase (TauD), an archetype alphaKG-dependent hydroxylase, is a non-heme mononuclear Fe(II) enzyme that couples the oxidative decarboxylation of alphaKG with the conversion of taurine to aminoacetaldehyde and sulfite. The crystal structure of taurine-alphaKG-Fe(II)TauD is known, and spectroscopic studies have kinetically defined the early steps in catalysis and identified a high-spin Fe(IV)-oxo reaction intermediate. The present analysis extends our understanding of TauD catalysis by investigating the steady-state and transient kinetics of wild-type and variant forms of the enzyme with taurine and alternative sulfonates. TauD proteins substituted at residues surrounding the active site were shown to fold properly based on their abilities to form a diagnostic chromophore associated with the anaerobic Fe(II)-alphaKG chelate complex and to generate a tyrosyl radical upon subsequent reaction with oxygen. Steady-state studies of mutant proteins confirmed the importance of His 70 and Arg 270 in binding the sulfonate moiety of taurine and indicated the participation of Asn 95 in recognizing the substrate amine group. The N97A and S158A variants are likely to undergo an increase in hydrophobicity and expansion of the substrate-binding pocket, thus accounting for their decreased K(m) toward pentanesulfonic acid compared to wild-type TauD. Stopped-flow UV-visible spectroscopic examination of the reaction of oxygen with taurine-alphaKG-Fe(II)TauD confirmed a minimal three-step sequence of reactions attributed to Fe(IV)-oxo formation (k(1)), bleaching to the Fe(II) state upon substrate hydroxylation (k(2)), rebinding of excess substrates (k(3)), and indicated that none of the steps exhibit detectable solvent k(H)/k(D) isotope effects. This demonstrates that no protons are involved in the rate-determining step of Fe(IV)-oxo formation, in contrast to heme iron oxygenases. The Fe(IV)-oxo species is likely to be utilized in conversion of the alternative substrates pentanesulfonic acid and 3-N-morpholinopropanesulfonic acid; however, this spectroscopic intermediate was not detected because of the decreased k(1)/k(2) ratio. With taurine, k(1) was shown to depend on the oxygen concentration allowing calculation of a second-order rate constant of 1.58 x 10(5) M(-)(1) s(-)(1) for this irreversible reaction. Stopped-flow analyses of TauD variants provided several insights into how the protein environment influences the rates of Fe(IV)-oxo formation and decay. The Fe(IV)-oxo species was not detected in the N95D or N95A variants because of a reduced k(1)/k(2) ratio, likely related to a decreased substrate-dependent conversion of the six-coordinate to five-coordinate metal site.
In vivo extracellular recordings were made in the subthalamic nucleus (STN) of intact control rats and rats with 5,7-dihydroxytryptamine (5,7-DHT) -produced lesion of dorsal raphe nucleus (DRN). The results showed that the firing rate of STN neurons in control rats and DRN-lesioned rats were (6.93+/-6.55) Hz and (11.27+/-9.31) Hz, respectively, and the firing rate of DRN-lesioned rats significantly increased when compared to the control rats (P<0.01). In control rats, 13% of STN neurons discharged regularly, 46% irregularly and 41% in bursts. In DRN-lesioned rats, 9% of STN neurons discharged regularly, 14% irregularly and 77% in bursts, the percentage of STN neurons firing in bursts was obviously higher than that of the control rats (P<0.01). In addition, the mean interspike interval coefficient of variation of STN neurons in control rats and DRN-lesioned rats were (0.05+/-0.04) and (0.11+/-0.09), respectively. The mean interspike interval coefficient of variation of DRN-lesioned rats was significantly higher than that of the control rats (P<0.001). These results show that the firing rate and the bursting pattern rate of neurons in STN of DRN-lesioned rats increase significantly, suggesting that DRN inhibits the neuronal activity of the subthalamic neurons in the intact rat.
The ring oxygen and sulfur analogs of lasofoxifene, 1a and 1b, were synthesized in an attempt to impart ERalpha selectivity, as found in the closely related dihydrobenzoxathiin compound I, recently discovered in these laboratories. The resulting isochroman and isothiochroman compounds were found to exhibit equipotent binding affinities to the ER isoforms and were less active in the inhibition of estradiol-triggered uterine growth when compared to I and lasofoxifene.
A simple mild solution method is developed to synthesize a novel nanoribbon multicomponent precursor. A new 1-D nanostructure, porous structured nanoribbons which are self-assembled by textured ZnO nanoparticles, was found upon removal of ligand molecules from the ribbonlike precursor. The structure combines 1-dimensional geometry with nanoparticle morphology and displays porous structure because there are gaps/pores between the particles. The orientation textured structure of the ZnO nanoparticles can be formed by controlling the annealing time. The ZnO nanoparticle nanoribbons exhibit a long geometrical shape, uniformity, a high aspect ratio, and different optical activities with different nanostuctures. These findings demonstrate a convenient, simple technique for production of the novel one-dimensional semiconductor nanostructure suitable for subsequent processing into nanostructures, materials, and devices.
OBJECTIVE: To set up a method for the detection of the serum protein fingerprint pattern by using the protein chip technology for exploration of serum protein fingerprint pattern models based on the artificial neural network in diagnosis of liver cancer. METHODS: One hundred and six serum samples form subjects with liver cancer, hepatocirrhosis, and healthy individuals were detected with protein biochip surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) for protein fingerprint pattern, and analyzed with the artificial neural network. The 106 samples were randomly put into a training group (n = 70, 35 patients with liver cancer, 14 patients with hepatocirrhosis, and 21 healthy individuals) and a blind test group (n = 36, 17 patients with liver cancer, 8 patients with hepatocirrhosis, and 11 healthy individuals). RESULTS: The serum protein fingerprint pattern model obtained by the artificial neural network from training group was used to detect the 36 unknown serum samples. The sensitivity and specificity of this method in detection of liver cancer were 88.2% (15/17) and 94.6% (18/19) respectively. CONCLUSION: In comparison with the traditional methods, this new method has higher sensitivity and specificity in diagnosis of liver cancer and should be further studied.
Heparan sulphate (HS) 3-O-sulphotransferase transfers sulphate to the 3-OH position of the glucosamine residue of HS to form 3-O-sulphated HS. The HS modified by 3-O-sulphotransferase isoform 3 binds to HSV-1 (herpes simplex virus type 1) gD (envelope glycoprotein D), and the resultant 3-O-sulphated HS serves as an entry receptor for HSV-1. In the present paper, we report the isolation and characterization of a novel HS 3-O-sulphotransferase isoform, designated HS 3-O-sulphotransferase isoform 6 (3-OST-6). Mouse 3-OST-6 gene was identified in the EST (expressed sequence tag) database and cloned into pcDNA3.1/Myc-His vector. A CHO (Chinese-hamster ovary) cell line that stably expresses 3-OST-6 (3OST6/CHO cells) was prepared. The disaccharide analysis of the HS isolated from 3OST6/CHO cells revealed that 3-OST-6 exhibits HS 3-O-sulphotransferase activity. Furthermore, 3OST6/CHO cells were susceptible to infection by HSV-1, but not by other alphaherpesviruses examined, suggesting that 3-OST-6 produces a specific entry receptor for HSV-1. Our results indicate that a new member of 3-OST family generates an entry receptor for HSV-1. The findings add to the growing body of evidence that HSV-1 entry is mediated by 3-O-sulphated HS generated by multiple members of 3-O-sulphotransferases.
Functional, conjugated molecular structures have been fabricated on Au nanoparticles via the Sonogashira coupling reactions.
Osteoporosis is a major and growing healthcare concern as the population ages. The genes of both a Arg-Gly-Asp (RGD)-containing peptide and parathyroid hormone (PTH) were used to reduce bone loss induced by ovariectomy (OVX) in rats. Plasmids with either RGD or PTH gene were delivered into the quadriceps of OVX rats. The expression of the genes was detected by RT-PCR and radioimmunoassay. Analysis of bone mineral density, bone mechanical testing and bone mineral content indicated an improvement in bone properties in both RGD-transferred and PTH-transferred rats compared to OVX rats. Gene transfer of either RGD or PTH is therefore a possible approach to prevent bone loss in OVX rats thus providing a potential method to prevent osteoporosis in clinical situations.
A new quantitative method for micro amounts of nucleic acids in aqueous solution is proposed using Eu3+-benzoylacetone (BA) complex as fluorescent probe in the presence of cetyltrimethyl-ammonium bromide (CTMAB). Under the optimum condition, the ratio of the fluorescence intensities with and without nucleic acids is proportional to the concentration of nucleic acid in the range of 1.0x10(-9) to 5.0x10(-6) g/mL for herring sperm DNA (hsDNA), 3.0x10(-9) to 1.0x10(-6) g/mL for calf thymus DNA(ctDNA) and 8.0x10(-9) to 1.0x10(-6) g/mL for yeast RNA (yRNA), and their detection limits are 0.33, 0.21 and 0.99 ng/mL, respectively. Actual sample (DNA of Arabidopsis thaliana) was determined satisfactorily. In addition, the interaction mechanism is also investigated.
Breast cancer has never had any good serum tumor markers. Therefore, we developed and evaluated a proteomics approach to searching for new biomarkers and building diagnostic models. SELDI-TOF-MS ProteinChip was used to detect the serum protein patterns of 49 breast cancer patients, 51 patients with benign breast diseases, and 33 healthy women. The diagnostic models were developed and validated using bioinformatics tools such as artificial neural networks and discriminant analysis. In total, four models were built and their sensitivities and specificities were satisfactory. The abilities of these models to diagnose stage I breast cancer were not worse than for stages II-IV (P>0.05). Four candidate biomarkers of breast cancer were found. The high sensitivity and specificity achieved by this method show great potential for the early detection of breast cancer and facilitation of discovering new and improved biomarkers.
The transport of an organic cation across a 4-5 nm liposome bilayer is observed in real time using second harmonic generation. It is proposed that an electrostatic barrier between the inside and outside of the liposome develops as the cation crosses the bilayer. This would explain why the SHG signal does not approach zero at long times. To test this mechanism, the antibiotic valinomycin, which can transport alkali ions across a phospholipid bilayer, is introduced into the system. It is found that the transport time is reduced by a factor of three from 90+/-2 s to 30+/-1 s with 1.25 x 10(-8) M valinomycin concentration, and a factor of fifteen to 6.2+/-0.2 s with 1.25 x 10(-8) M valinomycin concentration. In addition, the SHG signal approaches zero, which further supports the presence of an electrostatic barrier that can be eliminated by the alkali ion transporter valinomycin.
Finding accurate biomarkers is key to early diagnosis and successful treatment of many otherwise incurable diseases. In this work, we study the problem of finding biomarkers through mass spectrometry (SELDI-TOF) spectra from cancerous and normal tissues. In contrast to the common practice of using vague methods such as genetic algorithms, or uninterpretable methods such as Support Vector Machines, we look for a method that is simple, intuitive, interpretable, usable, and more accurate. We introduce decision lists to this domain. Our experiments on clinical cancer datasets demonstrate that decision lists can achieve more accurate results than other methods. More interestingly, the resulting decision lists are more interpretable for possible causal relationship between cancer and differentially expressed proteins, and directly usable in clinical biomarker design. In particular, our approach is capable of finding multiple biomarkers with high sensitivity and specificity. Such a feature will provide clues for medical experts to thoroughly investigate the roles of protein in cancer development and progression.
A rod-shaped, Gram-positive bacterium, strain TNJL143-2(T), having N-acyl-D-amino acid amidohydrolase (D-aminoacylase) activity, was isolated from a soil sample from Natori, Japan. It was a non-spore-forming, strictly aerobic bacterium without motility, showing a temperature optimum for growth of 30 degrees C and a pH optimum for growth of 5-7. The 16S rRNA gene sequence of the strain showed the highest similarities to members of the genus Microbacterium, in particular, Microbacterium aerolatum, Microbacterium foliorum and Microbacterium phyllosphaerae. The chemotaxonomic characteristics, including the compositions of cellular menaquinones, cellular fatty acids and cell-wall amino acids, were consistent with those described for the genus Microbacterium. The G+C content of the genomic DNA was determined as 69.1 mol%. DNA-DNA hybridization studies using type strains of M. aerolatum, M. foliorum and M. phyllosphaerae showed only low levels of relatedness (11-12 %). On the basis of these phenotypic and genotypic results, a novel species, Microbacterium natoriense sp. nov., is proposed, with TNJL143-2(T) (=JCM 12611(T)=ATCC BAA-1032(T)) as the type strain.
The premotor cortex of macaque monkeys is currently subdivided into at least six different subareas on the basis of structural, hodological and physiological criteria. To determine the degree of divergence/convergence of thalamocortical projections to mesial [supplementary motor area (SMA)-proper and pre-SMA] and lateral (PMd-c, PMd-r, PMv-c and PMv-r) premotor (PM) subareas, quantitative analyses were performed on the distribution of retrograde labelling after multiple tracer injections in the same animal. The results demonstrate that all PM and SMA subareas receive common inputs from several thalamic nuclei, but the relative contribution of these nuclei to thalamocortical projections differs. The largest difference occurs between subareas of SMA, with much greater contribution from the mediodorsal (MD) and area X, and a smaller contribution from the ventral lateral anterior (VLa) and ventral part of the ventral lateral posterior (VLpv) to pre-SMA than to SMA-proper. In PM, differences between subareas are less pronounced; in particular, all receive a significant contribution from MD, the ventral anterior (VApc) and area X. However, there are clear gradients, such as increasing projections from MD to rostral, from VLa and VLpv to caudal, and from dorsal VLp (VLpd) to dorsal premotor subareas. Intralaminar nuclei provide widespread projections to all premotor subareas. The degree of overlap between thalamocortical projections varies among different PM and SMA subareas and different sectors of the thalamus. These variations, which correspond to different origin and topography of thalamocortical projections, are discussed in relation to functional organizations at thalamic and cortical levels.
Mutations in copper/zinc superoxide dismutase (SOD1) account for 10-20% of a familial form of amyotrophic lateral sclerosis (ALS). A common feature of SOD1 mutants is abnormal aggregation of the aberrant SOD1 in neurons and glia. We now report that in ALS transgenic mouse models the constitutively expressed heat shock protein 70 (Hsp70) is mislocalized into aggregates together with mutant SOD1 and ubiquitin. Forcing increased synthesis of Hsp70 ameliorates both aggregate formation and toxicity in primary motor neurons in culture. However, chronic increase in an inducible form of Hsp70 to about 10-fold its normal level is shown here not to affect disease course or pathology developed in mice from accumulation of any of three familial ALS causing SOD1 mutants with different underlying biochemical characteristics. Therefore, increasing Hsp70 to a level that is protective in mouse models of acute ischemic insult and selected neurodegenerative disorders is not sufficient to ameliorate mutant SOD1-mediated toxicity.