Biomedical subjects

Y Pan

Publications and source records attributed to Y Pan.

At least 145 records · Page 8Linked to original sources

PubMed1998

Isolation and recovery of 2-aminoethanol, N-methyl-2-aminoethanol, and N,N-dimethyl-2-aminoethanol from a copper amine aqueous matrix and from amine-treated sawdust using liquid-liquid extraction and liquid-solid extraction combined with capillary gas chromatography-ion-trap mass spectrometry.

An analytical method for the rapid isolation and recovery of the homologous series of 2-aminoethanols, a class of organic compounds of importance to wood preservative treatment, is successfully developed. The method is applied to an aqueous solution of copper amine (copper[II] hydroxide complexed monoethanolamine) and to copper-amine-treated sawdust. The method incorporates a gas chromatograph-ion-trap mass spectrometer. A discussion of the secondary equilibrium effects involved when ionizable analytes are extracted from an aqueous phase with respect to organic bases is presented. Using 2-propanol as the extractant coupled to a salt-saturated aqueous phase results in recoveries of 63% for 2-aminoethanol, 51% for N,N-dimethyl-2-aminoethanol, and 56% for N-methyl-2-aminoethanol for a single liquid-liquid extraction. The choice of 2,2,2-trifluoroethanol as an internal standard is found to be quite suitable. A comparison of the precision and accuracy for an external versus an internal mode of instrument calibration demonstrates that the internal standard mode is preferable for this manual injection.

Algorithms↗

PubMed1998

Peptide-bound methionine as methionine sources for protein accretion and cell proliferation in primary cultures of ovine skeletal muscle.

Ruminants have high concentrations of peptide-bound amino acids in the circulation. Earlier studies in our laboratory showed that a myogenic cell line (C2C12) developed from mouse skeletal muscle and a mammary epithelial cell line (MAC-T) developed from bovine mammary epithelial tissues are able to utilize peptides as amino acid sources. In this study, primary cultures of ovine myogenic satellite cells were evaluated for their ability to use peptide-bound methionine as a source of methionine for protein accretion and cell proliferation. The basal medium contained methionine-free Dulbecco's modified Eagle's medium supplemented with 6% desalted fetal bovine serum. Treatment media included the basal medium supplemented with no methionine, methionine or one of 22 methionine-containing peptides. No protein or DNA accretion was observed in the presence of basal medium alone. Growth responses to all of the peptides were obtained, with protein and DNA accretion ranging from 49 to 107% and from 45 to 144% of the corresponding methionine response, respectively. These results indicate that the ovine myogenic satellite cells possess the ability to utilize methionine-containing peptides as methionine sources for protein accretion and cell proliferation.

Animals↗

PubMed1998

One or more serum factors promote peptide utilization in cultured animal cells.

We have shown previously that MACT-T and C2C12 cells utilize methionine-containing di- to octapeptides as methionine sources for protein accretion and cell proliferation in the presence of 60 mL/L desalted fetal bovine serum. In this study, serum factors that may regulate the use of peptides as amino acid sources in C2C12 and MAC-T cells were examined. The basal media contained methionine-free Dulbecco's modified Eagle's medium supplemented with 4.0 mL/L bovine serum lipids, 10 mL/L chemically defined lipid concentrate, bovine insulin (1 mg/L), 30 mL/L low protein serum replacement (LPSR-1) or 60 mL/L desalted animal serum. Treatment media included basal media supplemented with no methionine, L-methionine, or one of the methionine-containing peptides. L-Methionine promoted protein and DNA accretion (P < 0.05) in the presence of desalted animal sera, insulin or LPSR-1. Methionine-containing peptides also promoted protein and DNA accretion (P < 0.05) in the presence of desalted animal sera or LPSR-1, but not with insulin, except methionylleucine. In a cell-free medium, fetal bovine serum hydrolyzed peptides to varying degrees. We conclude that animal sera contain one or more factors that regulate utilization of peptides as amino acid sources for C2C12 and MAC-T cells.

Animals↗

PubMed1998

Varying the mechanical properties of bone tissue by changing the amount of its structurally effective bone mineral content.

The effect of fluoride ions on the mechanical properties of bone tissue in tension was investigated with an in vitro model. Structurally effective Bone Mineral Content (BMC) of bovine bone tissue was changed by fluoride ion treatment. First, bovine cortical bone specimens were treated with a detergent solution in order to increase the diffusion rates of the treatment ions across the samples. After the initial treatment, different ion solutions were used to treat the tension samples (fluoride, sodium and chloride). Ionic strength and pH were varied. Experimental results showed that the sodium chloride solutions of different ionic strengths, at physiological and high pH, do not affect the mechanical properties of bone tissue in tension. However, uniform fluoride treatment across the samples reduced the mechanical strength of bone tissue by converting small amounts of bone mineral to mostly calcium fluoride. This action reduces the structurally effective BMC and also possibly effects the interface bonding between the bone mineral and the organic matrix of the bone tissue.

Animals↗

PubMed1998

Environmental stress and domoic acid production by Pseudo-nitzschia: a physiological perspective.

Production of domoic acid (DA) by the pennate diatom Pseudo-nitzschia multiseries is associated with physiological stress caused by silicate (Si) and/or phosphate (P) limitation. Such limitation may promote DA synthesis by (1) reducing primary metabolic activity, thus making available necessary precursors, high energy compounds, and cofactors, and (2) favoring the expression of genes involved in the biosynthesis of this toxin. In the case of Si and P-limitation, DNA synthesis and the progression through the cell division cycle are slowed, perhaps prolonging or arresting the cells in the stage of the division cycle which is most conducive to DA production. However, N-limitation results in an insufficient pool of cellular free N, which restricts synthesis of this nitrogenous toxin. A continuous supply of photophosphorylated high-energy intermediates (e.g., ATP and NADPH) is necessary for DA synthesis. In order to better understand the mechanism(s) of DA production, more studies are needed to elucidate: (1) the details of the biosynthetic pathway, (2) the regulation of enzymes involved in the pathway, (3) the relation between DA synthesis and the cell division cycle, (4) the cellular compartmentalization of DA biosynthesis, and (5) other environmental factors that may trigger DA production. Finally, these studies should be extended to include toxigenic Pseudo-nitzschia species other than P. multiseries, to confirm the commonality of these mechanisms.

Cell Division↗

PubMed1998

[Teratogenic effects of arsenic on rats].

OBJECTIVE: To further clarify the effects of arsenic on pregnant rats, fetuses, fetal cells and to verify the experimental results in vitro, and to study the developmental toxicity and its mechanisms of arsenic in depth. METHODS: Teratogenic methods in vivo combined with scanning electron microscopy and histochemical techniques were used in rats. RESULTS: No apparently toxic symptoms or deaths were observed in rats exposed to various doses of arsenic trioxide of 0, 1, 4 and 10 mg/kg. Fetal death rates in rats were 10.2%, 17.4%, 24.8% and 61.1%, proportions of skeletal deformity were 1.89%, 3.12%, 17.28% and 78.57%, and embryo deformity rates were 3.16%, 5.32%, 13.79% and 40.48% 48 hours after exposure, respectively for those exposed to various doses of arsenic. Damage in fetal epidermal cells and cavities of different size between cell surface and cell junction in multiple sites could be seen under scanning microscope. Dysrhaphia, body anomalies and small limb bud, etc. were main manifestation of embryo deformity. There was a close relationship between nitric oxide and anomalies in fetal development, with a dose-response pattern, showed by inducible nitric oxide synthetase (iNOS) histochemical examinations. In vivo staining showed that excessive apoptosis could be induced by arsenic. And, teratogenic mechanisms of arsenic was analyzed in various ways. CONCLUSION: Arsenic has certain teratogenic effects on rats in vivo.

Animals↗

PubMed1998

Changes of skin perfusion after photodynamic therapy for port wine stain.

OBJECTIVE: To obtain an objective assessment of the curative effectiveness of photodynamic therapy (PDT) for port wine stain (PWS), we investigate the relationship between the microvascular perfusion changes of PWS and the blanching of the lesions before and after PDT. METHODS: Twenty-four patients (18 females and 6 males with a total of 28 lesions) suffering from PWS were treated with PDT. The lesions of various extents were located on the face and neck. After intravenous injection of photosensitizer hepatoporphyrin derivative (HpD), the copper vapor laser was adopted as light source and the lesions of PWS were irradiated. The laser Doppler perfusion imager (LDI) was used to measure the microcirculatory perfusion of PWS before and after PDT and comparison with the normal skin was done. RESULTS: All the lesions showed remarkable decrease of tissue perfusion after PDT. It was shown that the mean, maximal and minimal values of tissue perfusion in the pre-treatment group were significantly higher than those in control group (P < 0.01). Six months after PDT, the mean, maximal and minimal values of perfusion with the lesions were reduced, with significant difference from pre-treatment group (P < 0.01), but no significant difference from control's. The colors of lesions were correlated with decrease of microcirculatory perfusion, which became lightened close to normal skin color without causing any scarring. CONCLUSIONS: PDT is one of the most effective modalities for PWS. The microcirculation perfusion can reflect the degrees of PWS objectively. The curative effectiveness of PDT for PWS is due to tissue microcirculation response.

Adolescent↗

PubMed1998

[The clinic significance of serum hyaluronate and tumor necrosis factor alpha levels in liver diseases].

Serum levels of hyaluronic acid (HA) and tumor necrosis factor alpha (TNF alpha) in 94 patients with various liver diseases and 31 healthy controls were studied by RIA, Serum TNF alpha in hepatitis, liver cirrhosis (LC) and primary hepatic carcinoma (PHC) was higher than that of the control. Serum HA in chronic hepatitis, LC and PHC was higher than that in the control. The serum level of HA showed a positive correlation with the serum level of TNF alpha. It is considered that the increase of serum HA indicates an early fibrogenic tendency in patients with liver diseases. TNF alpha is involved in the formation of hepatic fibrosis.

Hepatitis, Chronic↗

PubMed1998

[Relation between methylmercury chloride-induced programmed cell death and the development of nervous system in rats].

The study was designed to reveal the role of programmed cell death (PCD, or apoptosis) induced by methylmercury chloride (MMC) in SD rat embryos, wish TdT-mediated dUTP nick end labeling (TUNEL), Nile blue sulfate (NBS) vital stailing electron microscopy (SEM) and in vivo teratogenic methods (TEM). Pregnant rats were intraperitoneally injected at gestation day 9.5 with doses of 0, 0.2, 0.4, 0.8, 1.6 and 3.2 mg/kg MMC and killed at 11.5 day later. Results showed that the PCD of embryonic nervous system was apparently dose dependent with MMC during rat head-fold stage. Observations under SEM and TEM showed that MMC caused pathologic changes of epithelia and organellae in embryonic brain such as atrophied or decreased microvilli cavernous damages and mitochondrial swelling and so on. Though MMC could result in developmental anomalies of embryonic brain and other organs, the main defect was open neural tube. The experiment study suggested that over PCD may be one of the teratogenic mechanisms of MMC on rat embryos, developing brain in particular.

Abnormalities, Drug-Induced↗

PubMed1998

[Autologous endothelial cell transplantation in meacacos].

OBJECTIVE: To lay a theoretical foundation for the clinical application of autologous endothelial cell transplantation. METHODS: Macaco endothelial cells derived from superficial veins were cultivated in vitro for 13.89 +/- 1.36 days. The multiplied cells were lined in vitro onto the luminal surface of expanded polytetrafluoroethylene (ePTFE) grafts precoated with fibrin glue and fibronectin, then cultivated further for 9 days. 15 macacos were divided randomly into two groups. The common iliac arteries of the exper mental animals (n = 10) were replaced with endothelialized grafts, those of control (n = 5) with untreated ones. RESULTS: The amount of endothelial cells increased for 147.93 +/- 88.68 folds. All the cells were diploid cells with a purity of 99%. The content of both 6-keto-PGF1a and vWF in the supernatant of primary and subcultured passages didn't have significant difference. Two hours and 9 days after cell seeding, the luminal surface of grafts were covered completely by a prominent, spindle-like endothelial monolayer underneath an even fibrin glue matrix could be seen. Nine days after seeding, the dense condensation of cytoskeleton on the luminal and basal side of cells increased apparently. Four weeks after grafts implantation 8/10 of experimental grafts, with a thickness of intima 80 +/- 12 microns, were patent; while the 5 control grafts were occluded. CONCLUSION: The endothelial cell transplantation could effectively increase the patency rate of synthetic blood vessel prosthesis.

Animals↗

PubMed1998

[Transient and stable expression of human ApoE7 gene in NIH/3T3 cell lines].

OBJECTIVE: To investigate the expressing profile of h-apoE7 gene under the regulation of MT-I promoter in mouse cells. METHODS: The eukaryotic expressing plasmid pME7 was constructed through cloning human apoE7 genomic DNA(6.0 kb) into pMT at the site of Bgl II/Hind III just under the control of the mouse metallothionein-I promoter. Transfection of pME7 plasmid into NIH/3T3 cell lines by Lipo-fectamine was performed. RESULTS: The transient expression of recombinant pME7 in NIH/3T3 cells showed that the expression was not restricted to human cells; The stable expression of pME7 demonstrated that the levels of h-apoE7 mRNA was highly related to the copies of integrated h-apoE7 gene. Whereas the results of ELISA implicated that the exogenous human apoE7 gene was transcribed, processed properly, and eventually translated into functional proteins. Furthermore, heavy metal (ZnSO4) could enhance the expressing level of h-apoE7 gene in transfected cell lines. The level of human apoE7 protein arised 45%-60% while induced. CONCLUSIONS: It was suggested that MT-I promoter could modulate the expression of recombinant h-apoE7 gene correctly. Therefore, cellular studies provided the scientific basis for establishment of h-apoE7 transgenic mouse models.

3T3 Cells↗

PubMed1998

[A histochemical study on baicalin].

Baicalin in the root of Scutellaria baicalensis was analysed histochemically by means of TLC and HPLC. It was determined that the content of baicalin in phloem was 11.08%, in xylem 7.86%, in phellem 2.19% and in centric decayed part 0.815%. Thus the quality of root of Scutellaria baicalensis is believed to consist in thin phellem, high ratio of phloem to xylem and absence of centric decayed part.

Drugs, Chinese Herbal↗

PubMed1998

[Magnetic resonant imaging diagnosis and differential diagnosis in choroidal melanoma].

OBJECTIVE: To evaluate the diagnostic value of magnetic resonant imaging (MRI) for choroidal melanoma. METHODS: 12 cases of choroidal melanoma were diagnosed by means of B-ultra-sonography, computed tomography (CT), MRI and pathology. RESULTS: The MRI features of melanoma were: T(1)WI shows high signal, and T(2)WI shows low signal. CONCLUSION: Besides B-ultra-sonography and CT, MRI is also valuable in the diagnosis and differential diagnosis of choroidal melanoma.

Adult↗

PubMed1998

[The manifestations of 496 cases with thyroid-related immune orbitopathy and normal thyroid function].

OBJECTIVE: To observe the clinical manifestations of thyroid-related immune orbitopathy (TRIO) with normal thyroid function. METHODS: 496 cases with TRIO were collected from 1973 to 1994 and their clinical manifestations were analyzed. RESULTS: The clinical manifestations showed that males are more than females. The disease occurred in middle aged persons with unilateral exophthalmos as the primary early manifestation. Most of the cases had the signs of eyelids and extraocular muscle involvement. CONCLUSIONS: The thyroid-related immune orbitopathy with normal thyroid function can be named thyroid-related immune orbitopathy-II. The clinical characteristics of this disease are unilateral, of signs of eyelids, exophthalmos and enlargement of eye muscles. The pseudo-tumors of the orbit are mainly considered for differential diagnosis.

Adolescent↗

PubMed1998

[A study of cytokines in pathogenesis of thyroid-related immune orbitopathy].

OBJECTIVE: To explore the pathogenesis of thyroid-related immune orbitopathy (TRIO). METHODS: Human orbital fibroblasts were cultured in vitro and immunohistochemical techniques were used to study cytokines that induce effect on HLA-II antigen expression of orbital fibroblasts. RESULTS: It is shown that interferon-gamma (IFN-gamma), interleukin-1 (IL-1) and tumor necrosis factor (TNF) could induce the expression of orbital fibroblast HLA-II antigens. The induced effect of IFN-gamma is of good linear correlations with time and concentration. CONCLUSION: HLA-II antigen expression can be induced by IFN-gamma, IL-1 and TNF. In the course of immune reaction and pathogenesis of TRIO, cytokines play important roles.

Cytokines↗

PubMed1998

The role of the T lymphocytic cell cycle and an autogenous lymphocytic factor in clinical medicine.

In this study 315 individuals (25 controls, 290 chemically sensitive immunocompromised patients) were investigated. Each patient had been on a standard therapy of avoidance of pollutants, nutritional supplementation, and injections of antigens for foods, and biological inhalants, but did not attain their immunological competence. Peripheral lymphocytes were collected and DNA histograms were constructed. The flow cytometer was used to evaluate the cell cycle, haematological, and other immunological profiles. From the other portion of the blood specimen, lymphocytes were propagated in vitro, harvested, and a lysate, termed the autogenous lymphocytic factor (ALF), was prepared. When treated with ALF, 88% of these individuals showed a significant (p < 0.001) clinical improvement which correlated with laboratory findings, involving regulation of abnormal cell cycles, increase in total lymphocytes and subsets T4, T8, (p < 0.05) and cell mediated immunity (CMI) response (p < 0.001). The ALF presumably acts as a biological response modifier. The cell cycle and ALF provide clinical tools for diagnosis and regulation of immunological incompetence.

Cell Cycle↗

PubMed1997

Structure and dynamics of pentaglycyl bridges in the cell walls of Staphylococcus aureus by 13C-15N REDOR NMR.

Whole cells and cell-wall fractions of Staphylococcusaureus have been labeled by various combinations of [1-13C]glycine, [15N]glycine, L--6-13C-lysine, L--6-15N-lysine, D--1-13C-alanine, and D--15N-alanine. The resulting materials have been examined using 13C and 15N solid-state, magic-angle spinning NMR techniques including cross-polarization, double cross-polarization, and rotational-echo double resonance. The results of these measurements indicate that the peptidoglycan glycyl bridges are complete (five units long) and form cross-links between three-quarters of all peptide stems. The pentaglycyl bridges are immobilized in lyophilized cell-wall fractions in a compact conformation with inter-residue spacings comparable to those of an alpha helix. The bridges have a similar compact conformation in intact whole cells, regardless of whether the cells have been lyophilized or were hydrated and frozen at -10 degrees C. The bridges are also in a time-averaged compact conformation in whole cells at 0 degrees C but with sizable structural fluctuations associated with local mobility. A small fraction of bridges are in extended-chain conformations.

Cell Wall↗

PubMed1997

Neurotactin, a membrane-anchored chemokine upregulated in brain inflammation.

Chemokines are small secreted proteins that stimulate the directional migration of leukocytes and mediate inflammation. During screening of a murine choroid plexus complementary DNA library, we identified a new chemokine, designated neurotactin. Unlike other chemokines, neurotactin has a unique cysteine pattern, Cys-X-X-X-Cys, and is predicted to be a type 1 membrane protein. Full-length recombinant neurotactin is localized on the surface of transfected 293 cells. Recombinant neurotactin containing the chemokine domain is chemotactic for neutrophils both in vitro and in vivo. Neurotactin messenger RNA is predominantly expressed in normal murine brain and its protein expression in activated brain microglia is upregulated in mice with experimental autoimmune encephalomyelitis, as well as in mice treated with lipopolysaccharide. Distinct from all other chemokine genes, the neurotactin gene is localized to human chromosome 16q. Consequently we propose that neurotactin represents a new delta-chemokine family and that it may play a role in brain inflammation processes.

Animals↗