Two-dimensional (17)O multiple quantum magic-angle spinning NMR of organic solids

We report two-dimensional (2D) (17)O multiple-quantum magic-angle spinning (MQMAS) NMR spectra for four (17)O-labeled organic compounds: [(17)O(2)]-D-alanine (1), potassium hydrogen [(17)O(4)]dibenzoate (2), [(17)O(4)]-D,L-glutamic acid.HCl (3) and [2,4-(17)O(2)]uracil (4). The high spectral resolution observed in the 2D (17)O MQMAS NMR spectra allows extraction of precise (17)O NMR parameters for all crystallographically distinct oxygen sites. We demonstrate that rotor synchronization is important in obtaining high-quality (17)O MQMAS spectra for organic compounds. Several issues related to the potential of (17)O MQMAS NMR for large biomolecular systems are also discussed.

[Expression and significance of urokinase-type plasminogen activator, its receptor, and type 2 inhibitor in giant cell tumor of bone]

OBJECTIVE

To investigate the expression and significance of u-PA, u-PAR and PAI-2 mRNA in giant cell tumor of bone.

METHODS

The expressions of u-PA, u-PAR and PAI-2 mRNA in 42 patients with giant cell tumor(GCT) of bone was detected with in situ hybridization.

RESULTS

The expression rates of u-PA, u-PAR, and PAI-2 mRNA of multinuclear giant cells (MGC) were 64.3%, 71.4% and 40.5%. Their expression rates in the mononuclear cells (MC) were 54.8%, 45.2% and 9.5%, respectively. The expression rates of u-PA mRNA in MGC, u-PA and u-PAR mRNA in MC of grade II and III lesions were significantly higher than those of grade I and non-recurrent lesions (P < 0.05). Close positive relation was observed between the expressions of u-PA mRNA of both cells, between the expressions of u-PAR and PAI-2 mRNA in MGC and also between the expressions of u-PA and u-PAR mRNA in MC. The expression rate in MGC was higher than that of MC significantly (P < 0.05).

CONCLUSION

The expressions of u-PA, u-PAR mRNA of giant cell tumor, especially in the mononuclear cells demonstrate lower differentiation and recurrent potential in giant cell tumor of bone. Mononuclear cells may be the main tumor cell in giant cell tumor of bone.

Flexible use of high-density oligonucleotide arrays for single-nucleotide polymorphism discovery and validation

A method for identifying and validating single nucleotide polymorphisms (SNPs) with high-density oligonucleotide arrays without the need for locus-specific polymerase chain reactions (PCR) is described in this report. Genomic DNAs were divided into subsets with complexity of ~10 Mb by restriction enzyme digestion and gel-based fragment size resolution, ligated to a common adaptor, and amplified with one primer in a single PCR reaction. As a demonstration of this approach, a total of 124 SNPs were located in 190 kb of genomic sequences distributed across the entire human genome by hybridizing to high-density variant detection arrays (VDA). A set of independent validation experiments was conducted for these SNPs employing bead-based affinity selection followed by hybridization of the affinity-selected SNP-containing fragments to the same VDA that was used to identify the SNPs. A total of 98.7% (74/75) of these SNPs were confirmed using both DNA dideoxynucleotide sequencing and the VDA methodologies. With flexible sample preparation, high-density oligonucleotide arrays can be tailored for even larger scale genome-wide SNP discovery as well as validation.

Controlled nucleation and growth of surface-confined gold nanoparticles on a (3-aminopropyl)trimethoxysilane-modified glass slide: a strategy for SPR substrates

The thickness of the gold film and its morphology, including the surface roughness, are very important for getting a good, reproducible response in the SPR technique. Here, we report a novel alternative approach for preparing SPR-active substrates that is completely solution-based. Our strategy is based on self-assembly of the gold colloid monolayer on a (3-aminopropyl)trimethoxysilane-modified glass slide, followed by electroless gold plating. Using this method, the thickness of films can be easily controlled at the nanometer scale by setting the plating time in the same conditions. Surface roughness and morphology of gold films can be modified by both tuning the size of gold nanoparticles and agitation during the plating. Surface evolution of the Au film was followed in real time by UV-vis spectroscopy and in situ SPRS. To assess the surface roughness and electrochemical stability of the Au films, atomic force microscopy and cyclic voltammetry were used. In addition, the stability of the gold adhesion is demonstrated by three methods. The as-prepared Au films on substrates are reproducible and stable, which allows them to be used as electrodes for electrochemical experiments and as platforms for studying SAMs.

Electrochemiluminescence of tris(2,2'-bipyridine)ruthenium(II) immobilized in poly(p-styrenesulfonate)-silica-Triton X-100 composite thin-films

The electrochemiluminescence (ECL) of tris(2,2'-bipyridine)ruthenium(II) [Ru(bpy)3(2+)] immobilized in poly(p-styrenesulfonate) (PSS)-silica-Triton X-100 composite films was investigated. The cooperative action of PSS, sol-gel and Triton X-100 attached Ru(bpy)3(2+) to the electrode strongly, and the presence of Triton X-100 prevented drying fractures of the sol-gel films during gelation and even on repeated wet-dry cycles. The modified electrode was used for the ECL detection of oxalate, tripropylamine (TPA) and NADH in a flow injection analysis (FIA) system with a newly designed flow cell. The detection scheme exhibited good stability, short response time and high sensitivity. Detection limits were 0.1, 0.1 and 0.5 micromol L(-1) for oxalate. TPA and NADH, respectively, and the linear concentration range extended from 0.001 to 1 mmol L(-1) for the three analytes. Applications of the flow cell in ECL and electrochemical detection, as well as the immobilization of reagents based on the cooperative action, are suggested.

[Determination of Ca, Mg, Fe, Mn, Cu and Zn in lixin pill by atomic absorption spectrophotometry]

Six elements in Lixin pill including calcium, magnesium, iron, manganese, copper and zinc were determined by atomic absorption spectrophotrometry. The results showed that there were comparatively rich Ca, Mg, Fe, Mn, Cu and Zn in Lixin pill and provided useful data for discussing the relation between trace elements in Lixin pill and cure for heart blood vessel disease.

Cadmium-induced apoptosis and phenotypic changes in mouse thymocytes

At present cadmium (Cd)-induced immunotoxicity and the mechanisms involved have not been fully elucidated. The main objective of the present study is to explore the apoptogenic property of Cd in primary cultured mouse thymocytes and its effect on cell surface marker expression and phenotypic changes. Cd-induced thymocyte apoptosis was determined by TdT-mediated dUTP nick end labeling (TUNEL) assay, DNA content/cell cycle analysis and DNA gel electrophoresis. The results showed that Cd was able to cause apoptosis in mouse thymocytes in a time- and dose-dependent manner. Moreover, different subsets of thymocytes possessed different susceptibility to the apoptotic effect of Cd, in the order of CD8+ > CD4- CD8- (double negative cells, DN) > CD4+ CD8+ (double positive cells, DP) > CD4+. Cd treatment also altered thymocyte surface marker expression, leading to evident phenotypic changes. Such changes were characterized by a decline in DP cells and a marked decrease in CD4+/CD8+ ratio, mainly due to a significant increase in CD8+ subsets. These observations help to obtain a better understanding of the immunotoxic and immunomodulatory effects of Cd.

Soil temperature and plant growth stage influence nitrogen uptake and amino acid concentration of apple during early spring growth

In spring, nitrogen (N) uptake by apple roots begins about 3 weeks after bud break. We used 1-year-old 'Fuji' Malus domestica Borkh on M26 bare-root apple trees to determine whether the onset of N uptake in spring is dependent solely on the growth stage of the plant or is a function of soil temperature. Five times during early season growth, N uptake and total amino acid concentration were measured in trees growing at aboveground day/night temperatures of 23/15 degrees C and belowground temperatures of 8, 12, 16 or 20 degrees C. We used (15NH4)(15NO3) to measure total N uptake and rate of uptake and found that both were significantly influenced by both soil temperature and plant growth stage. Rate of uptake of 15N increased with increasing soil temperature and changed with plant growth stage. Before bud break, 15N was not detected in trees growing in the 8 degrees C soil treatment, whereas 15N uptake increased with increasing soil temperatures between 12 and 20 degrees C. Ten days after bud break, 15N was still not detected in trees growing in the 8 degrees C soil treatment, although total 15N uptake and uptake rate continued to increase with increasing soil temperatures between 12 and 20 degrees C. Twenty-one days after bud break, trees in all temperature treatments were able to acquire 15N from the soil, although the amount of uptake increased with increasing soil temperature. Distribution of 15N in trees changed as plants grew. Most of the 15N absorbed by trees before bud break (approximately 5% of 15N supplied per tree) remained in the roots. Forty-six days after bud break, approximately one-third of the 15N absorbed by the trees in the 12-20 degrees C soil temperature treatments remained in the roots, whereas the shank, stem and new growth contained about two-thirds of the 15N taken up by the roots. Total amino acid concentration and distribution of amino acids in trees changed with plant growth stage, but only the amino acid concentration in new growth and roots was affected by soil temperature. We conclude that a combination of low soil temperature and plant developmental stage influences the ability of apple trees to take up and use N from the soil in the spring. Thus, early fertilizer application in the spring when soil temperatures are low or when the aboveground portion of the tree is not actively growing may be ineffective in promoting N uptake.

[Effect of silver carp stocking and fertilization on plankton community in enclosures in saline-alkaline ponds]

The effect of silver carp (Hypophthalmichthys molitrix) stocking and fertilization on plankton community of enclosures ecosystem in saline-alkaline ponds were studied. After stocking silver carp in enclosures, the abundance, chlorophyll-a content and primary productivity of phytoplankton increased, and the biomass of phytoplankton was mainly composed by small species, such as diatom and green algae. Moreover, Euglnophyta and Chrysophyta were also subdominant species. The biomass of zooplankton decreased with fish stocking, and that of Cladocera was greater in control than in fish-culture enclosures. Zooplankton community was dominated by larger species such as Daphnia carinata in control enclosures. Fertilization, especially applying inorganic fertilizer, significantly increased the abundance and primary productivity of phytoplankton and the biomass of zooplankton. Although the biomass of plankton in the enclosures applied organic fertilizer was greater than that of control enclosures, the primary productivity and chlorophyll-a content of phytoplankton, the diversity index of plankton, and the P/R ratio were very low, and thus, silver carp grew slowly. The effect of filter feeding fish and applying fertilizer on the structure of plankton community was also discussed.

[Water quality of closed polyculture of penaeid shrimp with tilapia and constricted tagelus]

A variety of water quality parameters were monitored in enclosures for the polyculture of penaeid shrimp with tilapia and constricted tagelus. The result showed that the environment of the polyculture systems was better than that of monoculture one. The fluctuation of DO in the water of polyculture enclosures was less violent, and their lowest values were obviously higher than those in monoculture ones. The value of COD and the number of bacteria in the water of polyculture enclosures were significantly lower than those in monoculture ones(t-test, alpha < 0.05), showing that the amount of organic matter in the water of polyculture systems was less than that in monoculture one. The biomass of plankton and the concentration of chlorophyll-a in the polyculture enclosures were also lower, showing that the suppression of the filtering animals to the plankton was obvious. The accumulation of N and P in the sediment of polyculture enclosures was 39.76% and 51.26%, lower than those of monoculture ones, respectively; and the number of bacteria in the sediment was 7.63% lower. Therefore, it is obvious that closed culture system can greatly decrease the effluent to the coastal waters caused by the pond culture industry, and decrease the pollution to the coastal waters.

The electrochemically induced conformational transition of disulfides in bovine serum albumin studied by thin layer circular dichroism spectroelectrochemistry

The conformational transition of disulfides in bovine serum albumin (BSA) induced by electrochemical redox reaction of disulfides were monitored by in-situ circular dichroism (CD) spectroelectrochemistry, with a long optical path thin layer cell and analyzed by a singular value decomposition least square (SVDLS) method. Electrochemical reduction of disulfides drives the left-handed conformation of disulfides changed into the right-handed. At open circuit, eight of the 17 disulfides were of left-handed conformation. Four of the 17 disulfides took part in the electrochemical reduction with an EC mechanism. Only one-fourth of the reduced disulfides returned to left-handed conformation in the re-oxidation process. Some parameters of the electrochemical reduction process, i.e. the number of electrons transferred and electron transfer coefficient, n = 8, alpha n = 0.15, apparent formal potential, E1(0') = -0.65(+/-0.01) V, standard heterogeneous electron transfer rate constant, k1(0) = (2.84 +/- 0.14) x 10(-5) cm s(-1) and chemical reaction equilibrium constant, Kc = (5.13 +/- 0.12) x 10(-2), were also obtained by double logarithmic analysis based on the near-UV absorption spectra with applied potentials.

In situ infrared spectroelectrochemical studies on adsorption and oxidation of nucleic acids at glassy carbon electrode

The adsorption and oxidation of yeast RNA and herring sperm DNA (HS DNA) at glass carbon (GC) electrode are studied by differential pulse voltammetry (DPV) and in situ FTIR spectroelectrochemistry. Two oxidation peaks of yeast RNA are obtained by DPV, whose peak potentials shift negatively with increasing pH. The peak currents decrease gradually in successive scans and no corresponding reduction peaks occur, thus indicating that the oxidation process of yeast RNA is completely irreversible. The IR bands in the 1200-1800 cm(-1) range, attributed to the stretching and ring vibrations of nucleic acid bases, show the main spectral changes when the potential is shifted positively, which gives evidence that the oxidation process takes place in the base residues. The oxidation process of HS DNA is similar to that of yeast RNA. The results both from DPV and in situ FTIR spectroelectrochemistry confirm that the guanine and adenine residues can be oxidized at the electrode surface, which is consistent with the oxidation mechanism of nucleic acids proposed previously.

Gene fusion and expression of heat-labile and heat-stable enterotoxins of enterotoxigenic Escherichia coli

The vaccine candidate comprising the genes that code the B subunit of the heat-labile enterotoxin (LT-B) and the heat-stable enterotoxin (ST) of enterotoxigenic E. coli (ETEC) had been constructed by recombinant genetic techniques. The 5'terminus of the gene encoding pro-ST was genetically fused to the 3'terminus of the LT-B gene. The pro-ST gene containing mature ST sequence and pro sequence which codes for the pro region of ST precursors was amplified by PCR from pSLN004 plasmid. To reduce toxicity of the ST in vitro was substituted Leu for Ala residue at position 14 of ST by oligonucleotide-directed site mutagenesis. For this construction, the expression of ST antigenicity and LT antigenicity were obtained when a five amino-acid or a nine-amino-acid linker were included between the LT-B and pro-ST moieties. The LT-B/pro-ST fusion peptides possessed no enterotoxic activity of heat-stable and heat-labile enterotoxins, and retained the ability to bind GM1 ganglioside. More importantly, these LT-B/pro-ST fusion peptides were immunogenic. The preparations containing the hybrid molecule elicited special antibodies that were to recognize native toxin in vitro.

In-situ FTIR study on adsorption and oxidation of native and thermally denatured calf thymus DNA at glassy carbon electrodes

In-situ Fourier transform infra-red (FTIR) spectra of native and thermally denatured calf thymus DNA (CT DNA) adsorbed and/or oxidized at a glassy carbon (GC) electrode surface are reported. The adsorption of native DNA occurs throughout the potential range (- 0.2 approximately 1.3 V) studied, and the adsorbing state of DNA at electrode surface is changed from through the C=O band of bases and pyrimidine rings to through the C=O of cytosine and imidazole rings while the potential shifts negatively from 1.3 V to -0.2 V. An in-situ FTIR spectrum of native CT DNA adsorbed at GC electrode surface is similar to that of the dissolved DNA, indicating that the structure of CT DNA is not distorted while it is adsorbed at the GC electrode surface. In the potential range of -0.2 approximately1.30 V, the temperature-denatured CT DNA is adsorbed at the electrode surface first, then undergoes electrochemical oxidation reaction and following that, diffuses away from the electrode surface.

Butyrate increases production of human chimeric IgG in CHO-K1 cells whilst maintaining function and glycoform profile

The influence of sodium butyrate on the production and glycosylation of recombinant mouse/human chimeric antibody by transfected CHO-K1 cells was investigated. We selected cells expressing 'wild-type' antibody with a human IgG3 heavy chain and a mutant of this molecule in which Phe 243 is replaced by Ala. These proteins have previously been shown to exhibit very different glycoform profiles with the mutant IgG being comprised of glycoforms having a high galactose and sialic acid content. Cell culture with 0-5 mM butyrate was shown to effect a 2-4-fold increase in antibody production whilst the induction of apoptosis was observed in a dose-dependent manner. The optimal butyrate concentration was observed to be 2 mM. The glycoform profile of each antibody produced in the presence of butyrate was analyzed by HPAEC-PAD and shown to be unchanged, relative to that produced in the absence of butyrate. Biological activity was evaluated by the ability of the antibodies to trigger superoxide generation, through Fc gamma RI, and shown to be independent of production in the presence or absence of butyrate. A similar increase in production was observed for a high antibody-producing cell line when expanded in a hollow fibre bioreactor under low-serum conditions (1%). These results demonstrated that butyrate is of value for increasing the productivity of CHO-K1 for recombinant IgG and does not compromise either glycosylation or biological activity.

A facile approach to immobilize protein for biosensor: self-assembled supported bilayer lipid membranes on glassy carbon electrode

A kind of solid substrate, glassy carbon (GC) electrode, was selected to support self-assembled lipid layer membranes. On the surface of GC electrode, we made layers of dimyristoylphosphatidylcholine (DMPG, a kind of lipid). From electrochemical impedance experiments, we demonstrated that the lipid layers on the GC electrode were bilayer lipid membranes. We immobilized horseradish peroxidase (HRP) into the supported bilayer lipid membranes (s-BLM) to develop a kind of mediator-free biosensor for H2O2. The biosensor exhibited fine electrochemical response, stability and reproducibility due to the presence of the s-BLM. As a model of biological membrane, s-BLM could supply a biological environment for enzyme and maintain its activity. So s-BLM is an ideal choice to immobilize enzyme for constructing the mediator-free biosensor based on GC electrode.

[Advance in studies on compensatory growth of aquatic animals after starvation or undernutrition]

This paper reviewed the studies on the compensatory growth of aquatic animals after starvation or undernourisment. The extent of compensatory growth, its affecting factors, physiological mechanisms, changes in chemical composition and dynamics of growth rate were discussed. The experimental design problems and the application prospects of related studied were also analyzed.

Electrochemiluminescent detection of chlorpromazine by selective preconcentration at a lauric acid-modified carbon paste electrode using tris(2,2'-bipyridine)ruthenium(II)

A new detection scheme for the determination of adsorbable coreactants of Ru(bpy)3(2+) electrochemiluminescent reaction is presented. It is based on selective preconcentration of coreactant onto an electrode, followed by Ru(bpy)3(2+) electrochemiluminescent detection. The coreactant employed is chlorpromazine. It was sensitively detected after 5-min preconcentration onto a lauric acid-modified carbon paste electrode. The linear concentration range was found to occur from 1 x 10(-8) to 3 x 10(-6) mol L-1 with a detection limit of 3.1 x 10(-9) mol L-1. The total analysis time is less than 10 min. As a result of selective preconcentration and medium exchange, such remarkable selectivity is achieved that reproducible quantitation of chlorpromazine in urine is possible.

Voltammetric and spectroscopic studies on methyl green and cationic lipid bound to calf thymus DNA

DNA interaction with cationic lipids promises to be a versatile and effective synthetic transfection agent. This paper presents the study on binding of a simple artificial cationic lipid, cetyltrimethylammonium bromide (CTAB), to calf thymus DNA (CT DNA) prior to the condensation process, taking methyl green (MG) as a probe. The results show that the CTAB binds to DNA through electrostatic interaction forming a hydrophobic complex, thus changing the micro-environment of duplex of DNA, so the binding state of MG and DNA is changed, and a complex CTAB-CT DNA-MG is formed. This fact suggests a new way to mediate the conformation of molecular assemblies of DNA and lipids.

Conformational transition of DNA in electroreduction studied by in situ UV and CD thin layer spectroelectrochemistry

Electrochemically induced three conformational transitions of calf thymus DNA from B10.4 to Z10.2-DNA and from B10.2 to B10.4 and to C-DNA in 10 mM phosphate buffer solution (pH 7.21) at glassy carbon electrode are found and studied by in situ circular dichroism (CD) thin layer spectroelectrochemistry with singular value decomposition least square (SVDLS) analysis. It indicates that the so-called B10.2 form and the C-form of DNA may be composed of B10.4 and left-A DNA and of B10.4 and right-A DNA, respectively. The irreversible electrochemical reduction of adenine and cytosine groups in the DNA molecule is studied by UV-Vis spectroelectrochemistry. Some electrochemical parameters alpha n = 0.17, E0' = -0.70 V (vs. Ag/AgCl), and the standard heterogeneous electron transfer rate constant, k0 = 1.8 x 10(-5) cm s(-1), are obtained by double logarithmic analysis and non-linear regression.

Silica sol-gel composite film as an encapsulation matrix for the construction of an amperometric tyrosinase-based biosensor

An amperometric tyrosinase enzyme electrode for the determination of phenols was developed by a simple and effective immobilization method using sol-gel techniques. A grafting copolymer was introduced into sol-gel solution and the composition of the resultant organic-inorganic composite material was optimized, the tyrosinase retained its activity in the sol-gel thin film and its response to several phenol compounds was determined at 0 mV vs. Ag/AgCl (sat. KCl). The dependences of the current response on pH, oxygen level and temperature were studied, and the stability of the biosensor was also evaluated. The sensitivity of the biosensor for catechol, phenol and p-cresol was 59.6, 23.1 and 39.4 microA/mM, respectively. The enzyme electrode maintained 73% of its original activity after intermittent use for three weeks when storing in a dry state at 4 degrees C.

Amperometric quantification of polar organic solvents based on a tyrosinase biosensor

A novel amperometric biosensor for quantification of the electrochemically inert polar organic solvents based on tyrosinase electrode was preliminarily reported. The biosensor was fabricated by simply syringing an aqueous solution of tyrosinase/PVAVP (PVAVP: copolymer of poly(vinyl alcohol) grafting with 4-vinylpyridine) onto glassy carbon electrode surface followed by drying the modified electrode at +4 degrees C in a refrigerator. The current generated from electrochemical reduction of quinone is a probe signal. The biosensor can be used for quantification of polar organic solvents, and its mechanism was characterized with in situ steady-state amperometry-quartz crystal microbalance experiments. The detection limit, sensitivity, and dynamic range for certain organic solvents are dependent on the kind and concentration of the substrate probe and the hydrophobicity of the immobilization matrix. The response time for all the tested organic solvents is less than 2 min.

[Effect of temperature and body weight on carbon budget of Penaeus chinensis]

The carbon budget of Penaeus chinensis feeding on polychaet worm(Neanthes japonica) was determined at various levels of temperature (20 degrees C, 25 degrees C, 30 degrees C) and body weights(0.271 +/- 0.041 g, 3.509 +/- 0.301 g, 11.062 +/- 1.027 g) from May to September, 1996. The results show that the carbon consumption was significantly affected by water temperature and body weight, which significantly increased with increasing temperature and decreasing body weight. The average carbon consumptions at 20 degrees C, 25 degrees C and 30 degrees C were 12.41, 19.12 and 26.08 mg.g-1.d-1, and those for 3 body weights were 36.06, 12.17 and 9.38 mg.g-1.d-1, respectively. The intake carbon allocation was not significantly affected by body weight, but significantly affected by water temperature. The proportions of carbon allocated to growth, fecal, exuviation and metabolism at three different temperatures were 31.23%, 4.28%, 7.94%, 56.45%; 26.83%, 2.92%, 6.69%, 65.79%; 16.86%, 2.38%, 5.99%, 74.76%, respectively.

The influence of glycosylation on the thermal stability and effector function expression of human IgG1-Fc: properties of a series of truncated glycoforms

Antibodies are multifunctional molecules that following the formation of antibody antigen complexes, may activate mechanisms to effect the clearance and destruction of the antigen (pathogen). The IgG molecule is comprised of three globular protein moieties (2Fab+Fc) linked through a flexible hinge region. While the Fabs bind antigens, the Fc triggers effector mechanisms through interactions with specific ligands, e.g. cellular receptors (FcgammaR), and the C1 component of complement. Glycosylation of IgG-Fc has been shown to be essential for efficient activation of FcgammaR and C1. We report the generation of a series of truncated glycoforms of IgG-Fc, and the analysis of the contribution of the residual oligosaccharide to IgG-Fc function and thermal stability. Differential scanning microcalorimetry has been used to compare the stabilities of the homogeneous glycoforms of IgG1-Fc. The results show that all truncated oligosaccharides confer a degree of functional activity, and thermodynamic stability to the IgG1-Fc, in comparison with deglycosylated IgG1-Fc. The same truncated glycoforms of an intact IgG1 anti-MHC Class II antibody are shown to exhibit differential functional activity for FcgammaRI and C1 ligands, relative to deglycosylated IgG1. The minimal glycoform investigated had a trisaccharide attached to each heavy chain and can be expected to influence protein structure primarily in the proximity of the N-terminal region of the C(H)2 domain, implicated as a binding site for multiple effector ligands. These data provide a thermodynamic rationale for the modulation of antibody effector functions by different glycoforms.

UVA-Induced DNA single-strand cleavage by 1-hydroxypyrene and formation of covalent adducts between DNA and 1-hydroxypyrene

1-Hydroxypyrene (HOP), a metabolite found in the urine of humans and laboratory animals exposed to polycyclic aromatic hydrocarbons (PAHs), is known to be both acutely toxic and genotoxic. It has been widely used as a biomarker for studying PAH exposure. In this research, we have found that, upon UVA irradiation, HOP causes DNA single-strand cleavages and forms HOP-DNA covalent adducts. The UVA-induced cleavage of supercoiled plasmid PhiX174 DNA is dependent upon both HOP concentration and UVA dosage. A longer irradiation time or higher HOP concentration induces more DNA cleavage. Results of the photocleavage experiments carried out in the presence of reactive oxygen species scavengers, histidine, sodium azide, mannitol, SOD, and desferal indicate that both the superoxide free radical and singlet oxygen are likely involved in causing DNA single-strand cleavage. The photocleavage is inhibited by the presence of an excited singlet-state quencher, KI, indicating that it is an excited-state reaction. Along with light-induced DNA cleavage, HOP also forms DNA covalent adducts while being degraded upon light irradiation. Light-induced degradation of 20 microM HOP follows first-order reaction kinetics in a 10% methanolic buffer (10 mM phosphate) solution in the absence or presence of 40 microM calf thymus DNA, with degradation half-lives of 20 or 15 min, respectively. The shorter degradation half-life in the presence of DNA is due to the formation of the HOP-DNA covalent adduct. The formation of the HOP-DNA covalent adduct is evidenced by comparing the UV-vis absorption and fluorescence emission spectra of the pure HOP with those of the HOP-DNA adduct. The covalent HOP-DNA adduct produced due to irradiation was purified by either extensive dialysis (3 x 500 mL buffer solutions), phenol and chloroform extraction followed by ethanol precipitation, or chloroform extraction alone. The isolated HOP-DNA adduct has an absorption peak at 353 nm, which is 8 nm red-shifted compared to that of free HOP. The fluorescence emission for HOP-DNA is at least 70 times weaker than that for free HOP in solution. In summary, the findings with HOP reveal that, in addition to metabolic activation that eventually leads to the formation of alkylated DNA adducts or other forms of DNA damage, HOP may be activated by light to produce DNA single-strand cleavage and covalent DNA adducts. These DNA lesions can be sources of toxicity.

[Study on clinical and molecular biological characteristics of infant acute leukemia]

OBJECTIVE

To study the clinical and molecular biological characteristics of infant acute leukemia (IAL).

METHODS

R and/or G banding technique was used for analysis of karyotype. DNA blotting for HRX gene rearrangement, and polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) for fusion gene detection.

RESULTS

Twenty cases of IAL were detected. HRX gene rearrangement was found in 10 cases, including HRX/AF-4 fusion gene in 5, HRX/AF-9 fusion in 2, and HRX/ENL fusion in 1, HRX self-fusion mediated by alu-repeat homologous recombination and HRX/EEN fusion each in one (HRX/EEN is a novel fusion gene reported for the first time).

CONCLUSION

High frequency of HRX gene rearrangement occurred in IAL, which is characterised by a massive leukemia cell burden and 11q23 translocation, forming fusion genes, especially HRX/AF-4 (about 50%). The results are of important significance in guiding clinical treatment and approaching the etiology of IAL.

[Study on the relationship between cadmium immunotoxicity and corticotropin-releasing factor]

To explore the relationship between cadmium immunotoxicity and corticotropin-releasing factor(CRF), murine T- and B-lymphocytes mitogen-induced proliferation function(3H-TdR incorporation method) and CRF levels of hypothalami and blood plasma were observed both in cadmium chloride(CdCl2) and CdCl2 + alpha-hCRF-treated animals in vivo. In cadmium-treated animals, T and B lymphocytes stimulation indexes were significantly lower than those in control(P < 0.05) with a dose dependent response. And interestingly, the central CRF levels in CdCl2-treated groups were significantly higher than those in control (P < 0.05), an increasing CRF level was also observed accompanied by the increase of CdCl2 level. In peripheral blood plasma, no significant difference of CRF levels was found among all groups(P > 0.05). When animals were treated with CdCl2 in combination with alpha-hCRF, no significant difference of B-lymphocyte proliferation function existed among the alpha-hCRF + CdCl2 groups (P > 0.05). Similar results were also observed in detecting T-lymphocyte proliferation function. Hypothalamic CRF levels among various doses of CdCl2 + alpha-hCRF groups showed no statistical difference, but all were higher than those in the control, and peripheral CRF levels had a trend to increase in alpha-hCRF + CdCl2 co-administrated groups. The results suggested that CdCl2 showed an immunosuppressive action upon murine T and B lymphocytes, CdCl2 could cause central CRF increase. alpha-hCRF could partially reduce the cadmium immunotoxicity. Central CRF-mediated immunomodulation was shown in cadmium immunotoxical effects on murine splenic lymphocytes.

[Effects of salinity and alkalinity on plankton and water chemical factors]

This paper dealt with the effects of increasing salinity and alkalinity on the chemical and hydrobiological factors in saline-alkaline ponds. The experiment was conducted in Daluhu Aquaculture Company, Gaoqing County, Shandong Province during July and August, 1998. Raw salt and NaHCO3 were used to adjust the salinity and alkalinity. The results showed that increasing alkalinity from HCO3- rsulted in the reduction of pH value, calcium ion concentration and COD in a short term. When alkalinity was increased from 6.64 +/- 0.40 to 13.47 +/- 0.31 mmol.L-1, no significant effect on plankton was observed. However, when salinity was increased from 2.10 +/- 0.22 to 11.29 +/- 0.99 g.L-1, it decreased the plankton biomass, species number and diversity index decreased, and affected the composition of plankton community structure.

Amperometric glucose biosensor based on lipid film

A novel glucose biosensor based on cast lipid film was developed. This model of biological membrane was used to supply a biological environment on the surface of the electrode, moreover it could greatly reduce the interference and effectively exclude hydrophilic electroactive material from reaching the detecting surface. TTF was selected as a mediator because of its high electron-transfer efficiency, and it was incorporated in the lipid film firmly. Glucose oxidase was immobilized in hydrogel covered on the lipid film. The effects of pH, operating potential were explored for the optimum analytical performance by using amperometric method. The response time of the biosensor was less than 20 s, and the linear range is up to 10 mmol l(-1) (corr. coeff. 0.9932) with the detection limit of 2 x 10(-5) mol l(-1). The biosensor also exihibited good stability and reproducibility.

[Study on beta-adrenoceptors mechanism of cadmium immunotoxicity]

OBJECTIVE

To study if the beta-adrenoceptors mechanism plays important role in the immunotoxicity of cadmium.

METHODS

The beta-adrenoceptor density, cellular cyclic adenosine 3',5' monophosphate (cAMP) levels, and DNA damage of rat spleen lymphocytes were studied. Beta-antagonist propranolol was used to block the beta-adrenoceptor.

RESULTS

In the single Cd administration group: beta-adrenoceptor density of spleen lymphocytes in the middle and high Cd concentration groups was higher than that in the non-Cd treated control group (P < 0.05), the levels of cAMP increased with the increase of Cd doses, and the result of the high Cd group was higher than that of the control group (P < 0.05). The proliferation function of T lymphocytes was lower in each Cd group than that in the control group (P < 0.05). Single cell gel electrophoresis (SCGE) detected that DNA damage of spleen lymphocytes in each Cd group were more severe than the control (P < 0.05). Pretreated with Pro group: After blocked with propranolol, beta-adrenoceptor density increased in the Pro control group and the density in all Cd treated groups was higher than the control group (P < 0.05), but all Cd treated groups showed no statistical significance than the Pro control group (P > 0.05). The cAMP levels, MTT and the subsets of T lymphocytes showed no statistical significance among all the groups (P > 0.05). The results of SCGE showed that DNA damage was most severe only in the high Cd group than other groups (P < 0.05).

CONCLUSION

The results suggest that the nerve-internal secretion system plays an important role in the immunotoxicity of cadmium, and the beta-adrenoceptor mechanism is important in the immunotoxic mechanism of cadmium.

Composition, synthesis, and assembly of the embryonic chick retinal basal lamina

To study the biology of basal laminae in the developing nervous system the protein composition of the embryonic retinal basal lamina was investigated, the site of synthesis of its proteins in the eye was determined, and basal lamina assembly was studied in vivo in two assay systems. Laminin, nidogen, agrin, collagen IV, and XVIII are major constituents of the retinal basal lamina. However, only agrin is synthesized by the retina, whereas the other matrix constituents originate from cells of the ciliary body, the lens, or the optic disc. The synthesis from extraretinal tissues infers that the retinal basal lamina proteins must be shed from their tissues of origin into the vitreous body and from there bind to receptor proteins provided by the retinal neuroepithelium. The fact that all proteins typical for the retinal basal lamina are abundant in the vitreous body and a new basal lamina is only formed when the vitreous body was directly adjacent to the retina is consistent with the contention of the vitreous body having a function in retinal basal lamina formation. Basal lamina assembly was also studied after disrupting the retinal basal lamina by intraocular injection of collagenase. The basal lamina regenerated after chasing the collagenase with Matrigel, which served as a collagenase inhibitor. The basal lamina was reconstituted within 6 h. However, the regenerated basal lamina was located deeper in the retina than normal by reconstituting along the retracted neuroepithelial endfeet demonstrating that these endfeet are the preferred site of basal lamina assembly.

[The expression and mechanism study of BMP in pleomorphic adenoma]

OBJECTIVE

One important pathological character of pleomorphic adenomas is that there is chorndriod component in the epithelial tumors. It is well known that bone morphogenetic protein (BMPs) plays important roles in the morphogenesis of hard tissue by inducing mesenchymal cells to differentiate into osteoblasts and chondroblasts in vivo. So we examined the expression of BMP and BMP2 mRNA in pleomorphic adenomas to study the pathological mechanism of chorndriod tissue formation.

METHODS

Using ABC immunohistochemistry method, 6 specimens of pleomorphic adenomas were examined with BMP antibody. Reverse transcriptase-polymerase chain reaction (RT-PCR) methods were developed for detecting BMP2 mRNA expression with special primers used to amplify the BMP2 cDNA mature domain fragment. The total RNA was extracted from frozen 6 specimens of pleomorphic adenoma and then reversed to cDNA by reverse transcription using AMV reverse transcriptase. PCR conditions were 94 degrees C for 20 seconds, 60 degrees C for 30 seconds, and 72 degrees C for 1 minute, 40 cycles, followed by extension for 30 minute at 72 degrees C. The reaction products were analyzed by electrophoresis.

RESULTS

BMP expression could be found in all of the specimens of pleomorphic adenoma examined by immunohistochemistry method. BMP2 RT-PCR product was detected in only 5 specimens that showed BMP2 mRNA existed in 5 specimens.

CONCLUSION

These results may be helpful to study the mechanism of pleomorphic adenoma. It is speculated that BMP secreted by tumor cells may play important roles in origin of osteoid tissue in pleomorphic adenoma by inducing neoplastic myoepithelial cells to differentiate to chondrocytes.

Stenting versus non-stenting after revascularization of chronic total coronary artery occlusion: short- and long-term clinical and angiographic results

OBJECTIVE

To investigate the short- and long-term clinician and angiographic outcome of stenting or angioplasty for chronic total coronary artery occlusion.

METHODS

A total of 95 patients with successful percutaneous transluminal coronary angioplasty (PTCA) for total occlusion coronary artery were identified out of 358 patients undergoing PTCA for chronic total occlusion. Patients were classified into two groups: Group A had selective stenting after successful PTCA and Group B only had PTCA. Clinical cardiac events including acute myocardial infarction (AMI) angina, death, repeat revascularization and angiographic variables were followed and analyzed.

RESULTS

A total of 85 of 95 patients (89%) completed clinical and angiographic follow-up. In group A (n = 42), 1 patient experienced an AMI while in group B, 2 patients experienced AMI and 1 died. In group A, the restenosis rate was 29%, reocclusion rate was 12% and recanularization rate was 19%, as compared to 58%, 22% and 45% respectively in group B (P < 0.001, P < 0.05 and P < 0.001, respectively).

CONCLUSIONS

Selective stent improves short- and long-term clinical and angiographic outcomes and is recommended in cases of chronic total occlusion independent of the primary PTCA results.

Transcriptional control elements and complex initiation pattern of the TATA-less bidirectional human thymidylate synthase promoter

The nucleotide sequences that are important for transcription of the human thymidylate synthase gene were analyzed by deletion and site-directed mutagenesis of the promoter region. Deletion analyses from the 5' and 3' ends indicated the presence of multiple positive and negative elements. The promoter had approximately the same strength in the normal or inverted orientation. The region between 161 and 141 nt upstream of the translational start codon was found to be both necessary and sufficient for high-level promoter activity in both directions and was designated the essential promoter region. This region, which is highly conserved in human, mouse and rat TS promoters, contains potential binding sites for Ets, Sp1, and LSF transcription factors. Site directed mutagenesis of each of these elements led to large decreases in promoter strength. However, inactivation of potential Sp1 and E2F elements adjacent to the essential promoter region led to increases in promoter strength. The transcriptional start site pattern was analyzed by S1 nuclease protection assays of mRNA isolated from cells transiently transfected with TS minigenes. Multiple start sites were detected, most of which were between 160 and 120 nt upstream of the AUG codon.

[Numerical dynamics of sediment bacteria in shrimp polycultural ecosystems]

The numerical dynamics of sediment bacteria was studied from May to September 1997, in the Shrimp Farm of Huanghai Fisheries Group Corporation with five experimental enclosures. It shows that the numbers of sediment bacteria ranged from 4.10 x 10(8) to 12.36 x 10(8) cells.g-1, averaged 8.09 x 10(8) +/- 2.17 x 10(8) cells.g-1, and increased gradually with increasing cultural time. The maximum was in 0-1 cm layer, and decreased obviously bellow 2-3 cm layer.

The impact of differential binding of wild-type RARalpha, PML-, PLZF- and NPM-RARalpha fusion proteins towards transcriptional co-activator, RIP-140, on retinoic acid responses in acute promyelocytic leukemia

Retinoic acid receptor (RA) heterodimer (RAR/RXR) activities have been shown to be repressed by transcriptional co-repressor, SMRT/N-CoR, in the absence of the ligand while upon all-trans retionic acid (ATRA) treatment, SMRT/N-CoR is dissociated from RARalpha leading to gene expression by the recruitment of transcriptional co-activators to the transcriptional complex. The difference in response to ATRA therapy between acute promyelocytic leukemia (APL) patients with PML-RARalpha fusion and PLZF-RARalpha fusion has recently been found to be partially due to the strong association of the transcriptional co-repressor, SMRT/N-CoR, with PLZF domain. We demonstrate that SMRT association, as with PML-RARalpha, can be released from NPM-RARalpha at pharmacological concentration of ATRA (10-6 M). Moreover, we show for the first time that the interaction between the transcriptional co-activator, RIP-140, and PML-, PLZF- or NPM-RARalpha fusion proteins can be positively stimulated by ATRA although they are less sensitive as compared with the wild-type RARalpha. Our results suggest that the dissociation of transcriptional co-repressors, SMRT/N-CoR, and recruitment of co-activators, eg RIP-140, to APL-associated fusion proteins constitute a common molecular mechanism in APL and underlie the responsiveness of the disease to RA therapy. Leukemia (2000) 14, 77-83.

[The effects of the complex of rhBMP2 and fibrin sealant on dental pulp]

OBJECTIVE

To investigate the reparative dentine formation induced by the complex of recombinant human bone morphogenetic protein 2 (rhBMP2) and fibrin sealant (FS) in dog tooth.

METHODS

Freshly exposed molars, premolars and cuspids were treated with the complex of rhBMP2/FS, rhBMP2 and Ca(OH)(2) paste which served as control.

RESULTS

The wound healing of exposed pulp treated with FS seemed to be better than that without FS. Dentine bridge formation was observed in pulp treated with the complex at 7 days, with rhBMP2, Ca(OH)(2) at 28 days. At 63 days after operation, the cases of tubular dentine bridge formation of the pulp treated with the complex were more than that of pulp treated with rhBMP2.

CONCLUSION

The synergistic effects of FS and the complex rhBMP2 exist and can be used as bioactive pulp capping agent.

Compact piezoelectric stacked actuators for high power applications

Small, hollow, multilayer actuators with a diameter of 3 mm were fabricated by the stacking method from piezoelectric hard lead zirconate titanate (PZT) ceramics. Langevin vibrators were also constructed with the hollow multilayer actuators. The performance capabilities of the actuator and Langevin vibrator samples were examined under high-power conditions. The high-power vibration level at a given sinusoidal drive voltage was significantly enhanced by using a multilayer structure under either a nonresonance or resonance condition. A maximum vibration velocity of 0.17 m/sec was obtained for the 9-layer actuator sample under nonresonance conditions. The vibration velocity was further improved with the Langevin vibrator driven at the resonance frequency. The temperature rise due to heat generation under high-power conditions was the immediate limitation on the maximum accessible vibration velocity for the stacked actuators.

[Analysis of 4 metal elements in 11 kidney tonic Chinese traditional medicines]

The contents of Zn, Cd, K and Na in 11 kidney tonic Chinese traditional medicines usually used in clinical practice were determined by FAAS. The results showed that element Zn, which is closely related to yang deficiency of the kidney, and the macro elements K and Na, which are essential to human-body, are very rich, but element Cd is lower. The relations between trace elements and the therapeutic efficacy were discussed, and it is concluded that the results are in agreement with clinical usage of medicines by herbalists.

[Significance of programmed cell death in C57BL/6N strain mouse palate process development and cleft palate formation]

OBJECTIVE

To observe the changes of programmed cell death (PCD) in C57BL/6N strain mouse cleft palate formation and study related gene of PCD in future.

METHODS

16 mice (gestation of 10 days, GD10) were divided into the experimental and control groups randomly, then the mice of the experimental group were dosed with retinoic acid(RA) 80 mg/kg, and the tissue slices of the embryo mouse were prepared for TdT-mediated dUTP nick end labeling (TUNEL) staining at GD13(14)(the 14th hour of the 13th day gestation), GD13(22), GD14(8), GD14(14), GD14(22), GD15(8), GD15(22) and GD16(8) respectively.

RESULTS

In the early development of palate process, the positive index of PCD was significantly higher in the experimental group than in the control group (P < 0.05).

CONCLUSION

The effects of RA on mesenchymal cells of the early development of palate process in the experimental group induce PCD, which result in the formation of small palate process and failure of fusing of the shelves.

[Surgical treatment of the functional obstruction of eustachian tube of middle-aged and aging people]

OBJECTIVE

To expore the effect and the way of palatosapingeus tendon-shortening surgery to treat the functional obstruction of eustachian tube of middle-aged and aging people.

METHOD

Seven cases of palatosapingeus tendon-shortening surgery were analyzed retrospectively.

RESULT

After operations the symptoms of all cases were relieved in a week. The tympanogram returned to type "A". The audiogram showed that the airbone gap disappeared. The shape of tympanic membrance returned to normal state. None of them recured in one-three year following up.

CONCLUSION

The effect of palatosapingeus tendon-shortening surgery is satisfactory so long as its surgical indication is correctly selected.

[Effect of cadmium on the beta-adrenoreceptor of splenic cell of rats and its immunotoxicity]

Rats were given cadmium(Cd) alone or Cd with beta-antagonist in order to study the effect of Cd on beta-adrenoreceptor density of rat splenic cells. The subsets of T-lymphocytes (CD4+, CD8+, CD4+/CD8+) and the proliferation of T lymphocytes were also detected. Cadmium alone stimulated and increased beta-adrenoreceptor density of rat splenic cell membrane. The immunotoxicity of Cd showed that the proliferation of T-lymphocytes was inhibited and the subsets of T cells were changed. But in the animals with beta-antagonist, the immunotoxicity of Cd on T cells was decreased. It is concluded that beta-adrenoreceptor may play an important role in the mechanism of cadmium on cell immunotoxicity.

[Determination of potassium, sodium, chromium and nickel in 11 Chinese traditional medicines by FAAS]

Four metallic elements in 11 Chinese traditional medicines such as potassium, sodium, chromium and nickel were determined by flame atomic absorption spectrophotometer. The results showed that there are rich metal elements, but the contents are different in 11 Chinese traditional medicines, providing useful data for discussing relations between trace elements in Chinese traditional medicines and the cure for CHD.

[Determination of 11 metal elements in niuhuang jiangya wan by atomic absorption spectrophotometer]

Eleven metal elements in niuhuang jiangya wan, including sodium, calcium, magnesium, potassium, iron, chromium, manganese, nickel, cadmium, copper and zinc, were determined by flame atomic absorption spectrophotometer. The results showed that there are rich metal elements in niuhuang jiangya wan and provided useful data for discussing the relation between trace elemtnts in niuhuang jiangya wan and cure for high blood pressure.

[The Raman spectra of rubidium titanyl arsenate]

The Raman spectra of rubidium titanyl arsenate (RTA) single crystal with different geometric arrangements were obtained and compared with those of rubidium titanyl phosphate (RTP), potassium titanyl arsenate (KTA) and potassium titanyl phosphate (KTP) single crystals. The assignments of various vibration modes were made according to the experimental results. The strong Raman scattering intensity implies that RTA crystal possesses large nonlinear optical property and the strongest scattering is from the TiO6 octahedron. From the mode splitting of AsO4 tetrahedron, we conclude that the distortion of AsO4 in RTA is larger than that of PO4 in KTP.

Distinct leukemia phenotypes in transgenic mice and different corepressor interactions generated by promyelocytic leukemia variant fusion genes PLZF-RARalpha and NPM-RARalpha

Acute promyelocytic leukemia (APL) is characterized by a specific chromosome translocation involving RARalpha and one of four fusion partners: PML, PLZF, NPM, and NuMA genes. To study the leukemogenic potential of the fusion genes in vivo, we generated transgenic mice with PLZF-RARalpha and NPM-RARalpha. PLZF-RARalpha transgenic animals developed chronic myeloid leukemia-like phenotypes at an early stage of life (within 3 months in five of six mice), whereas three NPM-RARalpha transgenic mice showed a spectrum of phenotypes from typical APL to chronic myeloid leukemia relatively late in life (from 12 to 15 months). In contrast to bone marrow cells from PLZF-RARalpha transgenic mice, those from NPM-RARalpha transgenic mice could be induced to differentiate by all-trans-retinoic acid (ATRA). We also studied RARE binding properties and interactions between nuclear corepressor SMRT and various fusion proteins in response to ATRA. Dissociation of SMRT from different receptors was observed at ATRA concentrations of 0.01 microM, 0.1 microM, and 1.0 microM for RARalpha-RXRalpha, NPM-RARalpha, and PML-RARalpha, respectively, but not observed for PLZF-RARalpha even in the presence of 10 microM ATRA. We also determined the expression of the tissue factor gene in transgenic mice, which was detected only in bone marrow cells of mice expressing the fusion genes. These data clearly establish the leukemogenic role of PLZF-RARalpha and NPM-RARalpha and the importance of fusion receptor/corepressor interactions in the pathogenesis as well as in determining different clinical phenotypes of APL.

Sol-gel thin-film immobilized soybean peroxidase biosensor for the amperometric determination of hydrogen peroxide in acid medium

An acid-stable soybean-peroxidase biosensor was developed by immobilizing the enzyme in a sol-gel thin film. Methylene blue was used as a mediator because of its high electron-transfer efficiency. The sol-gel thin film and enzyme membrane were characterized by FT-IR, and the effects of pH, operating potential, and temperature were explored for optimum analytical performance by using the amperometric method. The H2O2 sensor exhibited a fast response (5 s), high sensitivity (27.5 microA/mM), as well as good thermostability and long-term stability. In addition, the performance of the biosensor was investigated using flow-injection analysis (FIA).

Ectomesenchymal stem cells and all-trans-retinoic acid induced apoptosis

OBJECTIVE

This study aimed to establish and characterize ectomesenchymal stem cells and further reveal the effects of all trans-retinoic acid (RA) on the biologic behaviors of these cells.

METHODS

Ectomesenchymal stem (EMS) cells of developing palatal processes were explanted from the palatal shelves of embryonic BALB/c mice. The characterization of EMS cells was accomplished by immunohistochemical analysis and growth curves. The action of RA on EMS cells was evaluated according to population doubling time and the terminal deoxyribonucleotidyl transferase dUTP nick end-labeling assay.

RESULTS

Primary culturing of EMS cells proceeded successfully. The results of immunohistochemistry showed that EMS cells stained neuron-specific enolase (+), S-100 (+), vimentin (+3), keratin (-), myoglobin (-) and factor VIII (-). The population doubling time of RA-treated EMS cells was much longer compared with nontreated EMS cells. RA also dramatically increased the number of apoptotic cells.

CONCLUSION

Ectomesenchymal stem cells may be undifferentiated. RA inhibited their proliferation and induced apoptosis. The inhibition of growth and excess apoptosis may contribute to the formation of cleft lip/palate and other orofacial congenital malformations.