Biomedical subjects

Y Su

Publications and source records attributed to Y Su.

At least 55 records · Page 3Linked to original sources

PubMed2001

Lack of protective effect by intermittent hypoxia on MPTP-induced neurotoxicity in mice.

In the study we report here, several lines of evidence support the preventive action of intermittent hypoxia against oxidative injuries in CNS. Our in vitro data showed that autooxidation and iron-induced lipid peroxidation were attenuated in cortical homogenates of intermittent hypoxia-treated animals. Furthermore, our preliminary study found that iron induced oxidative injuries were abolished in rat brain after intermittent hypoxic treatment (paper submitted). Several antioxidative defensive systems improve in response to intermittent hypoxia. Since attenuation of autooxidation and iron-induced lipid peroxidation were observed in cortical homogenates of intermittent hypoxia-treated mice, the lack of prevention by intermittent hypoxia of MPTP-induced neurotoxicity may be due to the MPTP action that is not oxidative related. Together with our previous studies, in which several antioxidants were shown to successfully prevent oxidative injuries, our data here suggest that intermittent hypoxia may offer a potential treatment for preventing CNS degenerative diseases.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed2001

[Repetitious sorption of phenol to organobentonites from water].

The properties and mechanisms for repetitious sorption of phenol to organobentonites from water were studied. Results showed that organobentonites could be used to sorb phenol from water many times with high removal rates. The sorption capacities of three single-cation organobentonites were 120 CTMAB-bentonites > 120 CPC-bentonites > 120 DTMAB-bentonites, when the original concentration of phenol was 1000 mg/L. The sorption mechanisms changed from adsorption to partition in the process of repetitious sorption. Sorption of phenol to CPC-bentonites could bring synergic sorption. The distribution coefficience (Kp) were related to the quantities of phenol on CPC-bentonites, while the distribution coefficience of phenol on CTMAB-bentonites and DTMAB-bentonite were constant.

Adsorption↗

PubMed2001

Retinoic acid regulated insulin-like growth factor gene expression in cord blood lymphocytes.

OBJECTIVE: To explore the immune promotion mechanism of retinoic acid (RA). METHODS: Reverse Transcription-Polymerase chain reaction (RT-PCR) was used to detect the gene expression of insulin like growth factor I (IGF-I) and IGF receptors (IGF-IR and IGF-IIR) in vitro, and their regulation by RA in human cord blood lymphocyte (CBL). RESULTS: Significant upregulation of IGF-I, IGF-IR and IGF-IIR mRNA was found at 6-24 hours in CBL incubated with physiologic concentrations of RA as compared to those without RA. CONCLUSION: The enhancement of IGF expression may be an important pathway for vitamin A to promote immune cellular functions.

Cells, Cultured↗

PubMed2001

[Studies on infiltration mechanism of adenoid cystic carcinoma: haptotaxis function assay of fibronectin].

OBJECTIVE: To investigate the invasion mechanism of adenoid cystic carcinoma (ACC) by ACC haptotaxis changes in fibronectin (FN). METHODS: Three strains of ACC cells were used. The haptotaxis changes in FN, and receptor changes in the cell membrane surface were determined. RESULTS: All three strains of ACC cells had remarkably greater migration ability than SCC cell. High level of alpha 2, alpha 3, alpha 6 and beta 1 receptor subunit types was found in the cell surface of ACC and SCC; and high level of alpha 5 in ACC3. High inhibition of haptotaxis reaction was found after blocked alpha 5 and beta 1 receptor subunit in ACC and a middle inhibition after blocked alpha 4. In SCC more strong inhibition was found after blocked alpha 1, alpha 4 and beta 1. CONCLUSIONS: This study indicates that ACC cells have greater invasion ability than SCC cells in FN and haptotaxis reaction of different receptor of tested cells in FN have some feature pattern.

Carcinoma, Adenoid Cystic↗

PubMed2001

[Studies on DNA amplification fingerprinting of cortex Magnoliae officinalis].

Total genomic DNA samples of Chinese traditional medicine(CTM) Cortex Magnoliae Officinalis ("Houpo"), its counterfeits and substitutes were amplified by DNA amplification fingerprinting(DAF). Their amplified DNA banding patterns were distinguished on PAGE. The results show that DAF can be used to identify CTM "Houpo", its counterfeits and substitutes, which is also quite valuable for correctly introducing original plant.

DNA Fingerprinting↗

PubMed2001

[An experimental study of the influence of burn on the expressions of IFN-gamma and IL-4 in T lymphocytes and on the expression of IL-12 in macrophages in mice].

OBJECTIVE: To investigate the influence of burn on the expressions of IFN-gamma and IL-4 in T lymphocytes and on the expression of IL-12 in macrophages in mice. METHODS: The mice inflicted by 12% TBSA burn on the back were employed as the model. The peritoneal macrophages (PMphis) were isolated and counted under light microscope (LM). The gene expression level of IL-12 P35 and P40 subunits was determined with RT-PCR. The ratio of spleen to body and splenic histology were also determined. Splenic T lymphocytes were isolated and the gene expression levels of IFN-gamma and IL-4 in the T lymphocytes were examined by RT-PCR. RESULTS: (1) PMphis decreased significantly on 3 postburn day (PBD) and recovered quickly thereafter. (2) The gene expressions of IL-12 P35 and P40 subunits in PMphis were enhanced obviously. (3) Splenic index increased evidently and the karyokinesis phase increased in splenic lymphocytes. (4) The expressions of IFN-gamma and IL-4 in splenic T lymphocytes increased postburn. CONCLUSION: The expressions of IFN-gamma and IL-4 in splenic T lymphocytes and the expressions of IL-12 in PMphis could be enhanced by burn injury.

Animals↗

PubMed2001

[The changes of serum levels of interleukin-6 and interleukin-8 in pregnant women with systemic lupus erythematosus].

OBJECTIVE: To assess the changes of serum levels of interleukin-6(IL-6) and interleukin-8 (IL-8) in pregnant women with stationary phase systemic lupus erythematosus (SLE). METHODS: Enzyme-linked immunosorbent assay (ELISA) was used to measure serum IL-6 and IL-8 from 14 pregnant women with stationary phase SLE (SLE group), 12 normal pregnant women (normal pregnant group) and 12 normal non-pregnant women (group normal non-pregnant). The later two groups are set as controls. RESULTS: The IL-6, IL-8 levels in group SLE patients are (20.31 +/- 5.70) ng/L and (48.80 +/- 9.17) ng/L, significantly higher than those in normal pregnant group [IL-6, IL-8 levels are (8.40 +/- 2.49) ng/L and (21.15 +/- 5.21) ng/L, respectively, P < 0.01)] and normal non-pregnant group [IL-6, IL-8 levels are (6.14 +/- 0.86) ng/L and (17.71 +/- 4.43) ng/L, respectively, P < 0.01]. However, there's no significant difference between the normal pregnant group and normal non-pregnant group (P > 0.05). CONCLUSION: Serum levels of IL-6, IL-8 may be helpful to monitor the progress of SLE during pregnancy.

Adult↗

PubMed2001

[Clindamycin soluble suppository-production and its efficacy in treating bacterial vaginosis].

OBJECTIVE: To make the soluble suppository of clindamycin which is an effective drug for treatment of Bacterial vaginosis and to treat patients in clinical trials. METHODS: Outpatients who had vaginal infections from Sept. 1998 to Jan. 1999 were investigated. The diagnoses of bacterial vaginosis were made according to Amsel's criteria and 80 patients were included in this study. They were divided into two groups to be treated respectively by metronidanole suppository and clindamycin suppository which were made by our hospital pharmacy. RESULTS: The cure rate of metronidanole was 87.5% and that of clindamycin 90.3%; No significant difference was noted between the two groups(P > 0.05). The new clindamycin suppository was not irritant and it was easy to dissolve in vagina. There was no discontinued treatment because of side-effect. CONCLUSION: The clindamycin suppository does not irritate the mucosa of vagina, it is an efficacious remedy for bacterial vaginosis.

Administration, Intravaginal↗

PubMed2000

Patterns of histone acetylation suggest dual pathways for gene activation by a bifunctional locus control region.

The five genes of the human growth hormone (hGH) cluster are expressed in either the pituitary or placenta. Activation of the cluster is dependent on a locus control region (LCR) comprising pituitary- specific (HSI,II, -15 kb), placenta-specific (HSIV, -30 kb) and shared (HSIII, -28 kb; HSV, -32 kb) DNase I hypersensitive sites. Gene activation in the pituitary is paralleled by acetylation of a 32 kb chromatin domain 5' to the cluster centered at HSI,II. In the present study we observed that acetylation of this region in placental chromatin was discretely limited to shared HSIII and HSV. Transgenic studies revealed placenta-specific activation of linked genes by a determinant (P-element) located 2 kb 5' to each of the four placentally expressed genes. A localized peak of histone acetylation was observed at these P-elements in placenta but not pituitary. These data support a model for bifunctional action of the hGH LCR in which separate positive determinants, HSI,II and the P-elements, activate their respective target genes by tissue-specific recruitment of distinctly regulated histone acetyl transferase activities.

Acetylation↗

PubMed2000

Low-temperature structure of indium quantum chains on silicon

The array of quasi-one-dimensional indium chains in the Si(111)- (4x1)-In surface reconstruction exhibits a phase transition to a low-temperature (8x2) phase. It has been suggested that this phase transition is related to a charge density wave (CDW) formation. The x-ray diffraction results presented here demonstrate that at 20 K the CDW has not yet condensed into a superstructure even though good transverse coupling was established. This indicates that CDW formation cannot be the driving force for the phase transition. Furthermore we elucidate the subtle highly anisotropic interchain correlations and reveal the detailed atomic structure of the low-temperature (8x2) phase.

Journal Article↗

PubMed2000

Mortality rates among carriers of ataxia-telangiectasia mutant alleles.

BACKGROUND: Mutations at the ataxia-telangiectasia locus cause a distinctive autosomal recessive syndrome in homozygotes and predispose heterozygotes to cancer and ischemic heart disease. OBJECTIVE: To examine mortality rates among persons carrying a mutated ataxia-telangiectasia gene. DESIGN: Retrospective cohort study. SETTING: The United States and Canada. PARTICIPANTS: 405 grandparents of patients with ataxia-telangiectasia. MEASUREMENTS: Ages at death and risk for death (from all causes, cancer, ischemic heart disease, and other causes) among carriers and noncarriers of ataxia-telangiectasia mutations. RESULTS: Compared with noncarriers, carriers of a mutated ataxia-telangiectasia allele had a significantly increased risk for death at 20 through 79 years of age (relative risk, 1.9 [95% CI, 1.3 to 2.8]) (P < 0.001). On average, carriers died 7 to 8 years earlier than noncarriers. Cancer caused most of the excess deaths, and ischemic heart disease caused the remainder. Among carriers, relative risk for death from cancer and ischemic heart disease before 80 years of age was 2.6 (CI, 1.4 to 4.7; P = 0.002) and 2.0 (CI, 1.0 to 4.0; P = 0.062), respectively. Compared with noncarriers, carriers who died of cancer were a mean of 4 years younger (P > 0.2) and carriers who died of ischemic heart disease were a mean of 11 years younger (P = 0.006). CONCLUSION: Carriers of mutations at the ataxia-telangiectasia locus, who make up 1.4% to 2% of the general population, have a higher mortality rate and an earlier age at death from cancer and ischemic heart disease than noncarriers.

Adult↗

PubMed2000

Development and evaluation of a glow discharge microwave-induced-plasma tandem source for time-of-flight mass spectrometry.

In this work, a new glow discharge, microwave-induced-plasma (GDMIP), tandem ion source was developed, characterized, and used in conjunction with time-of-flight mass spectrometry. This tandem source was designed to be simple and compact The GD and the MIP unit are independent and demountable, providing flexibility in tuning and operating. The microwave plasma can be formed with very low power (a few watts) and overlapped with the glow discharge. The discharge current increased with the addition of microwave discharge when the GD was operated in constant-voltage mode, and the amplitude of the current increase was found to be related to microwave power, discharge pressure, and sampling distance. With the addition of microwave discharge, significant signal enhancement was achieved under a discharge pressure of 2.0 Torr and a discharge voltage of 500 V with 2.0-mm sampling distance. Enhanced factors of analyte signals ranging from approximately 1 to nearly 10 could be obtained with MIP boosting, while no significant change in noise level was observed. This new tandem source provides improved performance in direct solid sample analysis.

Journal Article↗

PubMed2000

Helium plasma source time-of-flight mass spectrometry: off-cone sampling for elemental analysis

In this paper, an atmospheric pressure, helium microwave-induced plasma (MIP) ion source coupled with an orthogonal acceleration time-of-flight mass spectrometer (TOFMS) is explored for elemental analysis. Studies of the relationship between ion signals and sampling distance of the MS reveal that background signals can be suppressed dramatically without sacrificing the signal intensities of analytes when the microwave plasma plume is off the tip of the sampler orifice. This "off-cone" ion sampling mode provides a technique to obtain nearly "clean" background spectra and, thus, eliminates the spectral interference from entrainment air and the working-gas species, making it possible to sensitively determine isotopes that suffered from spectral interference in ICPMS and MIPMS (such as 40Ca, 52Cr, 55Mn, and 56Fe). On the other hand, since the high-temperature plasma is kept away from the sampler aperture, off-cone sampling places little demand on the cooling device and the lifetime of the sampler plate can be extended. The instrumental system can provide a fairly good mass resolution of 1100 (fwhm). The detection limits (3sigma) in the tens of picograms per milliliter level for the elements studied can be achieved with a digital oscilloscope. These detection limits can be easily improved with an advanced detection system, which is currently available in commercial markets.

Journal Article↗

PubMed2000

Critical fluctuations and quenched disordered two-dimensional charge stripes in La(5/3)Sr(1/3)NiO4

Using high-resolution x-ray scattering, we have demonstrated the existence of quenched disordered charge stripes in a single crystal of La (5/3)Sr (1/3)NiO (4) at low temperatures. Above the second-order transition critical scattering was observed due to fluctuations into the charge stripe phase. The charge stripes are shown to be two dimensional in nature both by measurements of their correlation lengths (xi(a) approximately 185 A, xi(b) = 400 A, and xi(c) approximately 25 A) and by the critical exponents of the charge strip transition. The charge stripe ordering did not develop long-range order even at low temperatures, indicating that the charge stripes are disordered and that the length scale of the disorder is quenched.

Journal Article↗

PubMed2000

A field-portable plasma source monitor for real-time air particulate monitoring

In this research, a novel portable instrument for on-site, real-time air particulate monitoring was developed. It is highly desirable to use microwave plasmas for on-site, real-time environmental and occupational hazard monitoring because they can be sustained with various gases at relatively low power and possess excellent detection capabilities for both metal and nonmetal air pollutants. In the new instrument design, a microwave plasma was selected as an excitation source and was used in conjunction with atomic emission spectrometry. A small, integrated spectrometer with a charge-coupled detector (CCD) was used for optical signal detection. An efficient, in situ air-sampling system was developed for direct sampling of air particles into the plasma. Characterization and calibration of the new instrument were achieved with an in-house-fabricated high-efficiency nebulization-desolvation system. Tolerance of the microwave argon plasma source to air introduction was tested, and the operational parameters were optimized. Analytical performance and the feasibility of the newly developed portable instrument for aerosol particle analysis were evaluated. Some advantages and possible applications of the new instrument are discussed. The instrument provides an innovative tool for rapid environmental and occupational hazard monitoring.

Journal Article↗

PubMed2000

The human growth hormone gene cluster locus control region supports position-independent pituitary- and placenta-specific expression in the transgenic mouse.

The human growth hormone (hGH) cluster contains five genes. The hGH-N gene is predominantly expressed in pituitary somatotropes, whereas the remaining four genes, the chorionic somatomammotropin genes (hCS-L, hCS-A, and hCS-B) and hGH-V, are expressed selectively in the placenta. In contrast, the mouse genome contains a single pituitary-specific GH gene and lacks any GH-related CS genes. Activation of the hGH transgene in the mouse is dependent on its linkage to a previously described locus control region (LCR) located -15 to -32 kilobases upstream of the hGH cluster. The sporadic, nonreproducible expression of hCS transgenes lacking the LCR suggests that they may be dependent on hGH LCR activity as well. To determine whether the hCS genes could be expressed with appropriate placental specificity, a series of five transgenic mouse lines carrying an 87-kilobase human genomic insert encompassing the majority of the hGH gene cluster and the entire contiguous LCR was established. All of the hGH cluster genes were appropriately expressed in each of these lines. High level expression of hGH was restricted to the pituitary and hCS to the labyrinthine layer of the placenta. The expression of the GH cluster genes in their respective tissues paralleled transgene copy numbers irrespective of the transgene insertion site in the host mouse genome. These studies have extended the utility of the transgenic mouse model for the analysis of the full spectrum of hGH gene cluster activation. Further, they support a role for the hGH LCR in placental hCS, as well as pituitary hGH gene activation, and expression.

Animals↗

PubMed2000

Phenylarsine oxide inhibits nitric oxide synthase in pulmonary artery endothelial cells.

The role of protein tyrosine phosphorylation during regulation of NO synthase (eNOS) activity in endothelial cells is poorly understood. Studies to define this role have used inhibitors of tyrosine kinase or tyrosine phosphatase (TP). Phenylarsine oxide (PAO), an inhibitor of TP, has been reported to bind thiol groups, and recent work from our laboratory demonstrates that eNOS activity depends on thiol groups at its catalytic site. Therefore, we hypothesized that PAO may have a direct effect on eNOS activity. To test this, we measured (i) TP and eNOS activities both in total membrane fractions and in purified eNOS prepared from porcine pulmonary artery endothelial cells and (ii) sulfhydryl content and eNOS activity in purified bovine aortic eNOS expressed in Escherichia coli. High TP activity was detected in total membrane fractions, but no TP activity was detected in purified eNOS fractions. PAO caused a dose-dependent decrease in eNOS activity in total membrane and in purified eNOS fractions from porcine pulmonary artery endothelial cells, even though the latter had no detectable TP activity. PAO also caused a decrease in sulfhydryl content and eNOS activity in purified bovine eNOS. The reduction in eNOS sulfhydryl content and the inhibitory effect of PAO on eNOS activity were prevented by dithiothreitol, a disulfide-reducing agent. These results indicate that (i) PAO directly inhibits eNOS activity in endothelial cells by binding to thiol groups in the eNOS protein and (ii) results of studies using PAO to assess the role of protein tyrosine phosphorylation in regulating eNOS activity must be interpreted with great caution.

Animals↗

PubMed2000

Characterisation of the gene for Drosophila amphiphysin.

A sequence similarity search of the Drosophila nucleotide database using vertebrate amphiphysin as a query identified a cDNA that encodes a Drosophila amphiphysin. The predicted protein has conserved sequence domains that should enable it to dimerise and bind to dynamin. Structural modelling suggests that the Src-homology-3 (SH3) domains of vertebrate and Drosophila amphiphysins are highly similar, supporting the putative ability of the latter to bind dynamin. However, the fly amphiphysin shows less conservation to sequences in the vertebrate amphiphysins that bind other endocytic components such as clathrin, AP-2 and endophilin. Amphiphysin is a single-copy gene that maps to position 49B on polytene chromosomes. Messenger RNA of this amphiphysin is expressed widely during embryogenesis and has elevated expression in a number of sites including the foregut, hindgut and epidermis, but not in the central nervous system. Taken together, these data are consistent with a role for Drosophila amphiphysin in endocytosis, but the details of this role may differ from that of vertebrate amphiphysins.

Amino Acid Sequence↗