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Biomedical subjects

S Dong

Publications and source records attributed to S Dong.

At least 73 records · Page 4Linked to original sources
PubMed1999

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.

Animals↗
PubMed1999

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.

Animals↗
PubMed1999

[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.

Animals↗
PubMed1999

[Cerebral protective effects of some compounds isolated from traditional Chinese herbs].

OBJECTIVE: To study the cerebral protective effects of some compounds isolated from traditional Chinese herbs. METHOD: Laser microcirculation dynamic analyzer and cultured rat cortical neurons were used. RESULT: Pueraria lobata flavonoids(LPF), Panax notoginseng saponins(PNS), oxymatrine, anisodamine and berberine could dilate microvessels and increase the cerebral blood flow of anesthetized mice's meninges. LPF, PNS, oxymatrine, and anisodamine also accelerated the flow of blood. Oxymatrine, like anisodamine, increased quantities of erythrocytes in high frequency movements. PNS could protect cultured rat cortical neurons from glutamate neurotoxicity. CONCLUSION: LPF, PNS, oxymatrine, anisodamine and berberine have certain protective effects on brain, but differ in mechanisms of action.

Alkaloids↗
PubMed1999

[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.

Animals↗
PubMed1999

[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.

Aged↗
PubMed1999

[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.

English Abstract↗
PubMed1999

[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.

Chromium↗
PubMed1999

[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.

Drugs, Chinese Herbal↗
PubMed1999

[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.

Cadmium↗
PubMed1998

Collagen XVIII is a basement membrane heparan sulfate proteoglycan.

The present study shows that collagen XVIII is, next to perlecan and agrin, the third basal lamina heparan sulfate proteoglycan (HSPG) and the first collagen/proteoglycan with heparan sulfate side chains. By using monoclonal antibodies to an unidentified HSPG in chick, 14 cDNA clones were isolated from a chick yolk sac library. All clones had a common nucleotide sequence that was homologous to the mRNA sequences of mouse and human collagen XVIII. The deduced amino acid sequence of the chick fragment shows an 83% overall homology with the human and mouse collagen XVIII. Similar to the human and mouse homologue, the chick collagen XVIII mRNA has a size of 4.5 kilobase pairs. In Western blots, collagen XVIII appeared as a smear with a molecular mass of 300 kDa. After treatment with heparitinase, the protein was reduced in molecular mass by 120 kDa to a protein core of 180 kDa. Collagen XVIII has typical features of a collagen, such as its existence, under non-denaturing conditions, as a non-covalently linked oligomer, and a sensitivity of the core protein to collagenase digestion. It also has characteristics of an HSPG, such as long heparitinase-sensitive carbohydrate chains and a highly negative net charge. Collagen XVIII is abundant in basal laminae of the retina, epidermis, pia, cardiac and striated muscle, kidney, blood vessels, and lung. In situ hybridization showed that the main expression of collagen XVIII HSPG in the chick embryo is in the kidney and the peripheral nervous system. As a substrate, collagen XVIII moderately promoted the adhesion of Schwann cells but had no such activity on peripheral nervous system neurons and axons.

Amino Acid Sequence↗
PubMed1998

Amperometric glucose biosensor based on sol-gel organic-inorganic hybrid material.

A new type of sol-gel organic-inorganic hybrid material was developed and used for the production of biosensors. This material is composed of silica sol and a grafting copolymer of poly(vinyl alcohol) with 4-vinylpyridine. It prevents the cracking of conventional sol-gel-derived glasses and eliminates the swelling of the hydrogel. The optimum composition of the hybrid material was first examined, and then glucose oxidase was immobilized in this matrix to demonstrate its application. The characteristics of the biosensor were studied by cyclic voltammetry and chronoamperometry. The biosensor exhibited a series of good properties: high sensitivity (600 nA mmol-1 L-1), short response time (11 s) and remarkable long-term stability in storage (at least 5 months). In addition, the characteristics of the second-generation biosensor with the use of tetrathiafulvalene as a mediator were discussed.

Biosensing Techniques↗
PubMed1998

Characterization of the structural and functional changes of hemoglobin in dimethyl sulfoxide by spectroscopic techniques.

Circular dichroism (CD), fourier transform infrared (FTIR), and fluorescence spectroscopy were used to explore the effect of dimethyl sulfoxide (DMSO) on the structure and function of hemoglobin (Hb). The native tertiary structure was disrupted completely when the concentration of DMSO reached 50% (v/v), which was determined by loss of the characteristic Soret CD spectrum. Loss of the native tertiary structure could be mainly caused by breaking the hydrogen bonds, between the heme propionate groups and nearby surface amino acid residues, and by disorganizing the hydrophobic interior of this protein. Upon exposure of Hb to 52% DMSO for ca. 12 h in a D2O medium no significant change in 1652 cm-1 band of the FTIR spectrum was produced, which demonstrated that alpha-helical structure predominated. When the concentration of DMSO increased to 57%: (1) the band at 1652 cm-1 disappeared with the appearance of two new bands located at 1661 and 1648 cm-1; (2) another new band at 1623 cm-1 was attributed to the formation of intermolecular beta-sheet or aggregation, which was the direct consequence of breaking of the polypeptide chain by the competition of S&z.dbnd6;O groups in DMSO with C&z.dbnd6;O groups in amide bonds. Further increasing the DMSO concentration to 80%, the intensity at 1623 cm-1 increased, and the bands at 1684, 1661 and 1648 cm-1 shifted to 1688, 1664 and 1644 cm-1, respectively. These changes showed that the native secondary structure of Hb was lost and led to further aggregation and increase of the content of 'free' amide C&z.dbnd6;O groups. In pure DMSO solvent, the major band at 1664 cm-1 indicated that almost all of both the intermolecular beta-sheet and any residual secondary structure were completely disrupted. The red shift of the fluorescence emission maxima showed that the tryptophan residues were exposed to a greater hydrophilic environment as the DMSO content increased. CO-binding experiment suggested that the biological function of Hb was disrupted seriously even if the content of DMSO was 20%.

Animals↗
PubMed1998

Self-gelatinizable copolymer immobilized glucose biosensor based on prussian blue modified graphite electrode.

A novel poly(vinyl alcohol) grafting 4-vinylpyridine self-gelatinizable copolymer was adapted to immobilize glucose oxidase. The reduction of hydrogen peroxide (H2O2) was detected at a Prussian Blue (PB) modified graphite electrode. A stable and sensitive glucose amperometric biosensor is described. The copolymer is a good biocompatible polymer in which the glucose oxidase retains high activity. Moreover, the copolymer can adhere firmly to the inorganic PB membrane. The sensor showed an apparent Michaelis-Menten constant of 18 +/- 0.2 mM and a maximum current density of 1.14 microA cm-2 mM-1. The linear range is from 5 microM to 4.5 mM glucose and the detection limit is 0.5 microM glucose. The catalytic efficiency of PB for the reduction of H2O2 is higher than that for the oxidation of H2O2. Glucose concentrations in serum samples from healthy persons and diabetic patients were determined using the sensor. The results compared well with those provided by the hospital using a spectroscopy method.

Biosensing Techniques↗
PubMed1998

[Determination of antioxidants BHT,BHA and PG in food with high performance liquid chromatography].

An accurate and rapid method for simultaneous determination of antioxidants butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and propyl gallate (PG) in food by reversed-phase high performance liquid chromatography was established. The sample was extracted with hexane. Being filtrated and dried by N2, the residues in evaporator was dissolved in a certain amount of water-C2H5OH (1:4, V/V) and filtered with 0.5 micron of filter membrane for HPLC analysis. The chromatographic conditions were Radial-PAK C12 column, methanol-water (92:8, V/V) mobile phase adjusted to pH = 3 with phosphoric acid and UV-280 nm detector. By using external standard method the analytical results showed that the coefficients of variation of PG,BHA and BHT were 0.61, 0.08 and 1.44 respectively, linear correlation coefficients were more than 0.999 and recoveries were 92%-98% (n = 6). The lowest detection limit was 0.5 mg/L.

Antioxidants↗
PubMed1998

[Clinical study on traumatic anterior instability of shoulder].

OBJECTIVE: To study the clinical diagnosis, conservative and surgical treatment of traumatic anterior instability of the shoulder. METHOD: Based on the experience in diagnosis and treatment of 41 patients, we put forward criteria for diagnosis and treatment of traumatic anterior instability of the shoulder. RESULT: Diagnostic criteria: (1) history of injury to the shoulder; (2) sharp pain in the anterior aspect of the shoulder and weakness and limitation of range of motion of the shoulder; (3) the positive apprehension sign and or anterior drawer test; (4) a Hill-Sachs bony lesion on roentgenogram and abnormal double contrast CT. TREATMENT: (1) rehabilitation program for the patients having symptoms less than 3 months and without anterior capsular rupture; (2) capsular repair and imbrication procedure for the patients having symptoms more than 3 months, or not satisfied to the rehabilitation treatment, or severe anterior capsular rupture on double contrast CT. The results of the treatment were satisfactory with average 16-month follow-up. CONCLUSION: The diagnostic criteria and the treatment principles help improve the results of treatment of shoulder injuries, further clinical study is needed for traumatic anterior instability of the shoulder.

Adult↗