Biomedical subjects

Juan Wang

Publications and source records attributed to Juan Wang.

71 records · Page 4Linked to original sources

PubMed2004

[Factors influencing isolation and cloning of chicken primordial germ cells].

Gonadal primordial germ cells (PGCs) were isolated from 4.5-7.5-day-old chicken embryos. Factors influencing isolation and cloning of chicken PGCs were analyzed in this study. The results attained were as follows: Chicken PGCs proliferated fast in presence of 10% FBS. At primary culture, PGCs were co-cultured with the gonadal stromal cells. For subculture the chicken PGCs were plated with mitotically inactive feeder layer cells. Further research found that the PMEF (primary mice embryonic fibroblast) feeder cells were the most suitable for the growth of PGCs. When the cell culture medium was supplemented with LIF, FGF, SCF and IGF-I, the chicken PGCs were in the best condition. The chicken PGCs were easier to clone when isolated from 5.5-day-old embryonic gonads. In addition, the proper digestion time was 40s when PGCs colonies were passaged.

Animals↗

PubMed2003

Liquid chromatography determination of 10-hydroxycamptothecin in human serum by a column-switching system containing a pre-column with restricted access media and its application to a clinical pharmacokinetic study.

A simple, rapid, sensitive column-switching HPLC method is described for the analysis of the 10-hydroxycamptothecin (HCPT) in human serum. A pre-column containing restricted access media (RAM) is used for the sample clean-up and trace enrichment and is combined with a C18 column for the final separation. The analytical time is 8 min. The HCPT is monitored with fluorescence detector, excitation and emission wavelengths being 385 and 539 nm, respectively. There is a linear response range of 1-1000 ng/ml with correlation coefficient of 0.998 while the limit of quantification is 0.1 ng/ml. The intra-day and inter-day variations are less than 5%. This analytic procedure has been applied to a pharmacokinetic study of HCPT in clinical patients and the pharmacokinetic parameters of one-compartment model are calculated.

Antineoplastic Agents, Phytogenic↗

PubMed2003

Modified resolution factor for asymmetrical peaks in chromatographic separation.

The quality of separation is measured by resolution factor (R(s)) between adjacent peaks. The current United States Pharmacopeia (USP) method for R(s) calculation assumes symmetrical peak shapes. In practice, perfectly symmetrical peaks are rarely encountered. The goal of this study was to correct the inaccuracy due to peak asymmetry by using a new formula for R(s) calculation. Peak tailing factor was incorporated into the formula for the calculation of R(s) to correct for the peak asymmetry. The resulting modified formula was compared with USP formula using simulated peaks and actual peaks. Through mathematical derivation, the modified R(s) was expressed as: R=[2(t(2)+W(2)/2(1-1/TF(2))-t(1)-W(1)/2(1-1/TF(1)))]/W(1)+W(2) where t(1) and t(2) are the retention times of two peaks, W(1) and W(2) are peak widths at baseline, TF(1) and TF(2) are USP tailing factors. All parameters used in the formula are available from commercial data analysis software. Comparisons of modified R(s) to USP R(s) showed that the modified R(s) provided a more accurate measure of peak separation at the baseline level.

Chromatography, High Pressure Liquid↗

PubMed2003

[A case-control study on balance function of attention deficit hyperactivity disorder (ADHD) children].

OBJECTIVE: To explore the character of the balance function of ADHD and difference with control. METHODS: Subjects were 80 ADHD children and 80 non-ADHD children classified according to the diagnostic criteria of Diagnostic and Statistical Manual of Mental Disorders (IV) and matched by age and sex. We used the Balance Master to evaluate their stability in different conditions. The CART was used to find the relationship between the balance function and the clinical symptoms. RESULTS: Under the conditions of firm surface with eyes closed(FS/EC), foam surface with eyes opened (FoS/EO) and eyes closed(FoS/EC), unilateral stance with eyes open(VS/EO) and closed(VS/EC), the sway velocity of ADHD children was higher significantly than that of the control. There was correlationship between the result of sway velocity under the condition of FoS/EC and the vestibular dysfunction, somasensory dysfunction in the sensory integration check scale, the performance IQ, verbal comprehension facter and freedom from distractibility facter in C-WISC and the hyperactivity index in conner scale. CONCLUSION: ADHD children have poor stability, abnormal sensory integration and visual, somatosensory, vestibular function deficits. There is correlation between the balance dysfunction and the clinical symptoms and the deficits in behaviour and cognition.

Adolescent↗

PubMed2003

Expression and activity of the signaling molecules for mitogen-activated protein kinase pathways in human, bovine, and rat lenses.

PURPOSE: The mitogen-activated protein kinase (MAPK) pathways play distinct roles in the lens. However, the expression patterns and activity levels of various components for these pathways have not been well-documented in vertebrate lenses, especially human lens. In the present study, the expressions and activities of extracellular signal-regulated kinase (ERK)-1/2/3, c-Jun NH2-terminal kinase (JNK)-1/2, p38 kinase, mitogen-activated protein kinase kinase (MEK)-1/2, and RAF1 were recorded in human, bovine, and rat lenses. METHODS: Human, bovine, and rat lenses were isolated from intact eyes. The epithelia and different layers of fiber cells were isolated from these lenses. Total proteins extracted from these samples were subject to analysis of the expression patterns and activity levels of the MAPKs and the activating kinases of ERK1/2. RESULTS: ERK1 and ERK2 were the most abundant MAPKs in terms of both protein and activity levels in all lenses. JNK1 and JNK2 were highly expressed in bovine lens, which differed from the pattern shared by human and rat lenses. p38 kinase was similarly expressed in bovine and rat lenses, but different from that in human lens. However, p38 kinase activity was exclusively detected in the epithelia. All lenses had MEK1/2 activity in their epithelia but the expression patterns of MEK1 and MEK2 differed in these lenses. RAF1 was expressed in the epithelia of all lenses, but its activity was detected only in rat lens. CONCLUSIONS: ERK1 and ERK2 are the most abundant MAPKs in the ocular lens, providing the basis for their multiple functions in lens development and pathogenesis. The dominant epithelial distribution of JNK1/2 and p38 kinase suggests that the lens epithelium is a major site for stress response. ERK1, p38 kinase, and PKCalpha can be used as molecular markers for aging.

Aged↗

PubMed2003

[8-(N,N-diethylamino)-n-octyl-3,4,5-trimethoxybenzoate inhibited the reduction of cerebral blood flow evoked by 5-HT and KCl in rats].

AIM: To investigate the impact of 8-(N,N-diethylamino)-n-octyl-3,4,5-trimethoxybenzoate (TMB-8) on the change of cerebral blood flow(CBF) induced by 5-HT or KCl in rats. METHODS: The CBF in rats was measured by a Laser-Doppler flowmeter. The cranial window field was superfused with artificial cerebral spinal fluid containing TMB-8, 5-HT or KCl. RESULTS: 12.5, 25 and 50 mumol.L-1 TMB-8 showed no significant effect on rest CBF in rats. 12.5, 25 and 50 mumol.L-1 TMB-8 apparently inhibited the decline of CBF evoked by 1 or 2 mumol.L-1 5-HT. When persistent reduction of CBF were evoked by 1 mumol.L-1 5-HT, TMB-8 markedly increased the CBF in a concentration-dependent manner. The reduction of CBF induced by 20 or 40 mmol.L-1 KCl was also suppressed by 12.5, 25 and 50 mumol.L-1 TMB-8. While persistent reduction of CBF was evoked by 20 mmol.L-1 KCl. TMB-8 markedly increased the CBF in a concentration-dependent manner. CONCLUSION: These results indicate that TMB-8 is effective in preventing and treating the reduction of CBF induced by 5-HT or KCl, and improved the supply of blood in rat brain during ischemia.

Animals↗

PubMed2003

[The non-trauma fluorescence analysis of the porphyrin in the blood of human superficial skin tissue].

The porphyrin compound in human body mainly includes hemoglobin, protoheme, protoporphyrin, coproporphyrin, uroporphyrin and so on. As we know, the metabolism of the porphyrin in human body depends on the physical conditions. It was found that the relative content of protoporphyrin (PPIX) and carotenoid in blood varied with the developing of the malignant tumor. A system, including Ti: sapphire laser, optical fiber delivery system, fluorescence probe, spectrometer CCD and computer, has been developed to examine the porphyrin in human superficial skin tissue without trauma. It was shown that the fluorescence spectrum of the porphyrin obtained from the superficial skin tissue of human earlobe has the same feature as that from the aqueous solution with PP IX.

Biomarkers, Tumor↗

PubMed2002

Identification and characterization of P15RS, a novel P15(INK4b) related gene on G1/S progression.

To screen genes involved in P15(INK4b) regulation during cell cycle, differential display method was applied to compare mRNAs from G(1) synchronized cells of MLIK6, which overexpressed P15(INK4b) gene, and its control MLC2. By using this approach, 15 cDNA fragments that were preferentially expressed in MLIK6 cells, but not in MLC2 cells, were screened out. A novel gene named P15RS was identified with further analysis. Combining the sequence from DD-PCR, homology analysis against EST database and RACE, a 4,404 bp complete cDNA sequence of P15RS was generated. Sequence analysis revealed that P15RS cDNA encoded a 312-amino-acid peptide containing a RAR domain that is involved in regulation of nuclear pre-mRNA, which suggests that P15RS may be a nuclear regulation protein. Genomic sequence analysis demonstrated that human P15RS gene was localized on chromosome 18q12 with seven exons and six introns. Expressing antisense P15RS in MLIK6 cells can up-regulate the expression of cyclinD1 and cyclinE. These data indicate that P15RS may act as a negative regulator in G(1) phase.

Amino Acid Sequence↗

PubMed2002

Localization of tumor by chemiluminescence probe during photosensitization action.

As a chemiluminescence (CL) probe, 3,7-dihydro-6-[4-[2-(N'-(5-fluoresceinyl) thioureido)ethoxy]phenyl]-2-methylimidazo[1,2-a]pyrazin-3-one dosium salt (FCLA) can sensitively and specifically react with singlet oxygen ((1)O(2)) and superoxide (O(2)(-)). Based on the fact that photosensitization action involves (1)O(2) generation, this report presents a novel method for localization of tumor mediated by FCLA. In experiments, FCLA was used as an optical reporter of (1)O(2) produced from photosensitization reaction of hematoporphyrin derivative. The effects of azide inhibition and deuterium enhancement on photosensitized CL indicated that (1)O(2) molecules generated during photosensitization action could be measured and imaged. In vivo experiments in vivo with tumor-bearing nude mice showed a clear CL image of tumor. The study suggests that CL imaging method may be applicable to the detection of (1)O(2) and the diagnosis of superficial tumors.

Animals↗

PubMed2002

Characterization of the initial burst release of a model peptide from poly(D,L-lactide-co-glycolide) microspheres.

In order to study the mechanism of initial burst release from drug-loaded poly(D,L-lactide-co-glycolide) (PLGA) microspheres, a model peptide, octreotide acetate, was encapsulated in PLGA 50/50 (M(w) approximately 50,000) microspheres using a double emulsion-solvent evaporation method. A simple and accurate continuous monitoring system was developed to obtain a detailed release profile. After different incubation times in the release medium, the morphology and permeability of the microspheres were examined using scanning electron and confocal microscopy (after immersing the microspheres in a fluorescent dye solution for 30 min), respectively. Both the external and internal morphology of the microspheres changed substantially during release of >50% of the peptide over the first 24 h into an acetate buffer, pH 4 at 37 degrees C. After 5 h, a 1-3 microm "skin" layer with decreased porosity was observed forming around the microsphere surface. The density of the "skin" appeared to increase after 24 h with negligible surface pores present, suggesting the formation of a diffusion barrier. Similar morphological changes also occurred at pH 7.4, but more slowly. Correlated with these results, the confocal microscopy studies (at pH 4) showed that the amount of dye penetrated inside the microspheres sharply decreased with time. In summary, over the first 24 h of drug release, a non-porous film forms spontaneously at the surface of octreotide acetate-loaded PLGA microspheres in place of an initially porous surface. These rapid alterations in polymer morphology are correlated with a sharp decline in permeability and the cessation of the initial burst.

Biocompatible Materials↗

PubMed2002

Experimental study on photodynamic diagnosis of cancer mediated by chemiluminescence probe.

A novel method of photodynamic diagnosis of cancer mediated by chemiluminescence probe is presented. The mechanism for photodynamic therapy involves singlet oxygen ((1)O(2)) generated by energy transfer from photosensitizers. (1)O(2) can react with 3,7-dihydro-6-[4-[2-(N'-(5-fluoresceinyl)thioureido)ethoxy]phenyl]-2-methylimidazo[1,2-a]pyrazin-3-one sodium salt (FCLA), which is a Cypridina luciferin analog and a specific chemiluminescence probe for detecting (1)O(2) and superoxide (O(2)(-)). The reaction of FCLA and (1)O(2) can give emission with peak wavelength at about 532 nm. In the present study, FCLA was chosen as an optical reporter of (1)O(2) produced from the photosensitization reaction of hematoporphyrin derivative in model solution and in nude mice with transplanted mammary cancer. Photosensitized chemiluminescence from the reaction of FCLA with (1)O(2) was detected by a highly sensitive Intensified Charge-Coupled Device detector. The chemiluminescence was markedly inhibited by the addition of 10 mmol/l sodium azide (NaN(3)) to the model solution and minor effects were observed at the addition of 10 micromol/l superoxide dismutase, 20 mmol/l mannitol and 100 microg/ml catalase, respectively, thus indicating that (1)O(2) generation from photosensitization reaction mainly results in light emission. Experiments in vivo with tumor-bearing mice showed a clear chemiluminescence image of tumor. The study suggests that this novel method may be applicable to the diagnosis of superficial tumors.

Animals↗

PubMed2002

Human telomerase accelerates growth of lens epithelial cells through regulation of the genes mediating RB/E2F pathway.

Telomerase is a specialized reverse transcriptase that extends telomeres of eukaryotic chromosomes. The catalytic core of human telomerase is composed of an RNA template known as hTER (human telomerase RNA) and a protein subunit named hTERT (human telomerase reverse transcriptase). We have been studying other functions of the telomerase besides its major role in telomere maintenance. In our previous work, we have demonstrated that the hTERT can functionally interact with a rabbit TER to regulate expression of other genes and also attenuate the induced apoptosis. Here we report that overexpression of hTERT in a human lens epithelial cell line accelerates growth of the transfected lens epithelial cells. Associated with the acceleration of cell growth, expression of p53, p21 and GCIP (Grap2 cyclin-D interacting protein) is downregulated in the hTERT-transfected cells. With the downregulation of p21 and GCIP, the retinoblastoma protein (RB) is completely hyperphosphorylated in the hTERT-transfected cells. As expected, in the presence of RB hyperphosphorylation, the E2F transactivity is upregulated. Inhibition of telomerase activity abolishes the observed growth acceleration and also the related molecular changes. Furthermore, expression of hTERT in telomerase-negative human lens epithelial cells derived from primary cultures also accelerates growth of the transfected cells. Taken together, our results suggest that hTERT, when overexpressed in human lens epithelial cells, accelerates cell growth rate through regulation of RB/E2F pathway and possibly other genes.

Blotting, Western↗

PubMed2002

A draft sequence of the rice genome (Oryza sativa L. ssp. indica).

We have produced a draft sequence of the rice genome for the most widely cultivated subspecies in China, Oryza sativa L. ssp. indica, by whole-genome shotgun sequencing. The genome was 466 megabases in size, with an estimated 46,022 to 55,615 genes. Functional coverage in the assembled sequences was 92.0%. About 42.2% of the genome was in exact 20-nucleotide oligomer repeats, and most of the transposons were in the intergenic regions between genes. Although 80.6% of predicted Arabidopsis thaliana genes had a homolog in rice, only 49.4% of predicted rice genes had a homolog in A. thaliana. The large proportion of rice genes with no recognizable homologs is due to a gradient in the GC content of rice coding sequences.

Arabidopsis↗

PubMed2002

Cloning and characterization of an acidic cytolysin cDNA from sea anemone Sagartia rosea.

A full-length cDNA of cytolysin (Src I) was isolated from the tentacle of Sagartia rosea (a representative species in China) by reverse transcription polymerase chain reaction. The cDNA with an open reading frame of 648 bp encodes a precursor protein of 216 amino acids, which contains a prepropeptide of 38 amino acids including a signal peptide of 19 amino acids and a propart of 19 amino acids. Lys-Pro at C-terminus of propart is a cleavage site for proline-endopeptidase-like protease. The mature cytolysin has a molecular mass of 19.6 kDa and a pI value of 4.8. Src I is an acidic cytolysin found in sea anemone and shares 75% amino acid sequence similarity to equinatoxin II (Eqt II). The predicted secondary structure of the mature cytolysin comprises 15% alpha-helix, 45% beta-sheet, and 40% random coil. The characteristic amphiphilic alpha-helix of cytolysin is located at the N-terminus of the processed Src I.

Amino Acid Sequence↗

PubMed2002

Human lymphocyte growth hormone stimulates interferon gamma production and is inhibited by cortisol and norepinephrine.

Lymphocyte growth hormone (L-GH) is distributed throughout the human immune system; however, its biologic role has not been defined. In order to clarify this issue, we determined if Candida, commonly used as a recall antigen, and IL-12, an important monocyte cytokine that stimulates the TH1 cytokine pathway, could stimulate L-GH mRNA synthesis in cultured human peripheral blood mononuclear cells (PBMCs). Both Candida and IL-12 produced significant (p<0.01) stimulation of L-GH mRNA synthesis and the TH1 cytokine, gamma interferon (IFN-gamma). These effects on IFN-gamma production were significantly (p<0.001) inhibited by a GH antagonist, suggesting that L-GH was acting by an autocrine or paracrine mechanism to enhance IFN-gamma production in these serum-free cultured cells. Concentrations of norepinephrine and cortisol achievable in humans during stress were able to significantly (p<0.001) decrease L-GH synthesis in the PBMCs. They also diminished IFN-gamma significantly (p<0.001), but not the TH2 cytokine, IL-10, in the supernatants of the cultured PBMLs. These studies suggest that L-GH plays a role in cellular immune function mediated via the TH-1 pathway.

Adult↗

PubMed2002

Detection of vitamin C-induced singlet oxygen formation in oxidized LDL using MCLA as a chemiluminescence probe.

In this study, it was observed that addition of vitamin C (vit C) to oxidized low-density lipoprotein (Ox-LDL) by cupric ions (Cu2+) could result in the formation of singlet oxygen (1O2). In experiments, 1O2 was detected by chemiluminescence method using a Cypridina luciferin analog, 2-methyl-6-(p-methoxyphenyl)-3, 7-dihydroimidazo [1, 2-a] pyrazin-3-one (MCLA), as a selective and sensitive chemiluminescence probe. Additional experimental evidence for the formation of 1O2 came from the quenching effect of sodium azide (NaN3) on vit C-induced chemiluminescence in the reaction mixture of LDL-Cu(2+)-MCLA. Analysis based on the experimental results demonstrated the plausible reaction mechanism is that vit C first converts Cu2+ to its reduced state and vit C becomes vit C radical itself, thereby stimulating the formation of peroxyl and alkoxyl radicals, and bimolecular reaction of peroxyl radicals results in 1O2 production in the systems studied.

Ascorbic Acid↗

PubMedDate not supplied

Rapid determination of rice seed vigour by spontaneous chemiluminescence and singlet oxygen generation during early imbibition.

Using a highly sensitive single photon counter, a spontaneous chemiluminescence (CL) study on rice (Oryza sativa L.) seeds stored in different years was carried out. We first observed that the degree of ageing in rice seeds was related to the intensity of spontaneous CL during early imbibition (0-30 min). Rice seeds stored for a shorter time had a stronger intensity of CL in early imbibition. The germination rate of rice seeds showed an obvious positive correlation with the intensity of spontaneous CL. Singlet oxygen ((1)O(2)) in rice seeds during early imbibition was investigated by a CL method using a cypridina luciferin analogue, 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo [1,2alpha] pyrazin-3-one (MCLA), as a selective CL probe. Additional experimental evidence for the formation of (1)O(2) came from the quenching effect of sodium azide (NaN(3)) on MCLA-mediated rice seeds' CL. Analysis based on the experimental results demonstrated that spontaneous CL in rice seeds during early imbibition was mainly contributed by singlet oxygen ((1)O(2)).

Germination↗