Biomedical subjects

S Mou

Publications and source records attributed to S Mou.

At least 19 recordsLinked to original sources

PubMed2001

Retention behavior of transition metals on a bifunctional ion-exchange column with oxalic acid as eluent.

The common eluents used with a bifunctional ion-exchange column (IonPac CS5A) for separating transition metals are pyridine-2,6-dicarboxylic acid and oxalic acid (Ox). When Ox is used, cadmium and manganese co-elute. Although much research has been done to overcome the Cd2+-Mn2+ co-elution problem, the role of lithium hydroxide in separating the transition metals has received little attention. In this study, it is found that when the Ox concentration is higher than 35 mM, Cu2+ elutes after Pb2+ and Ox plays a predominant role in the retention behavior of the seven metals. When Ox concentration is lower than 35 mM especially when its concentration (25 mM) is half of the usually used standard concentration (50 mM), Cu2+ elutes before Pb2+, and at the same time, Mn2+ and Cd2+ can also be baseline separated. Lithium hydroxide plays a predominant role in the separation of the metals separated by cation exchange. So, lithium hydroxide is used to adjust the pH of the eluent. The use of an isocratic elution (25 mM Ox/LiOH/2 mM Na2SO4, pH 3.88) allows the separation of seven metals (Cu2+, Pb2+, Co2+, Mn2+, Cd2+, Zn2+ and Ni2+) in a single run. The effects of inorganic modifiers such as NaNO3, Na2SO4 and Na4P3O7 on retention behavior of the metals are also investigated.

Chromatography, Ion Exchange↗

PubMed2001

IL-7 administration alters the CD4:CD8 ratio, increases T cell numbers, and increases T cell function in the absence of activation.

IL-7 is vital for the development of the immune system and profoundly enhances the function of mature T cells. Chronic administration of IL-7 to mice markedly increases T cell numbers, especially CD8(+) T cells, and enhances T cell functional potential. However, the mechanism by which these effects occur remains unclear. This report demonstrates that only 2 days of IL-7 treatment is needed for maximal enhancement of T cell function, as measured by proliferation, with a 6- to 12-fold increase in the proportion of CD4(+) and CD8(+) T cells in cell cycle by 18 h of ex vivo stimulation. Moreover, a 2-day administration of IL-7 in vivo increases basal proliferation by 4- and 14-fold in CD4(+) and CD8(+) T cells, respectively. These effects occur in the absence of cytokine production, increases in most activation markers, and changes in memory markers. This enhanced basal proliferation is the basis for the increase in T cell numbers in that IL-7 induces an additional 60% and 85% of resting CD4(+) and CD8(+) T cells, respectively, to enter cell cycle in mice given IL-7 for 7 days. These results demonstrate that in vivo administration of IL-7 increases T cell numbers and functional potential via a homeostatic, nonactivating process. These findings may suggest a unique clinical niche for IL-7 in that IL-7 therapy may increase T cell numbers and enhance responses to specific antigenic targets while avoiding a general, nonspecific activation of the T cell population.

Animals↗

PubMed2001

Preparation and blood compatibility of polysiloxane/liquid-crystal composite membranes.

Polysiloxane/liquid crystal composite membrane was first suggested to be used as biomaterials. In this work, the polydimethyl-methylhydrosiloxane and polydimethyl-methylethylenesilosiane, as a substrate, were blended with cholesteryl oleyl carbonate (COC) in tetrahydrofuran, and then crosslinked into membranes on glass plates by means of the platinum catalyst at 110 degrees C for 20 min. The effects of the liquid-crystal content in composite membranes on the formation of liquid-crystal phase were verified by the observation of optical polarization microscopy. The relationship between the morphology of the composite membranes and blood compatibility was identified by the dynamic blood-clotting tests, haemolysis ratio measurement, platelet adhesion and SEM observation. The results show that the blood-compatibility of composite membranes with the concentration of liquid crystal 20, 30% (wt) is more excellent than that of other composite membranes.

Biocompatible Materials↗

PubMed2001

Comparison of clindamycin phosphate vaginal cream with triple sulfonamide vaginal cream in the treatment of bacterial vaginosis.

BACKGROUND: Triple sulfonamide vaginal cream has been used to treat bacterial vaginosis for many years. There are few studies in which triple sulfonamide cream has been compared with newer regimens. GOAL: To compare the efficacy and safety of clindamycin phosphate vaginal cream with that of triple sulfonamide vaginal cream in the treatment of bacterial vaginosis. STUDY DESIGN: In this double-blind, randomized multicenter study, nonpregnant women 16 years of age or older with symptomatic bacterial vaginosis were assigned to receive either 2% clindamycin phosphate vaginal cream or triple sulfonamide vaginal cream for 7 days. Follow-up visits were conducted 5 to 10 days and 25 to 39 days after completion of treatment. RESULTS: Clinical cure or improvement at 25 to 39 days was noted in 55 (69.6%) of 79 assessable participants who received clindamycin vaginal cream and in 33 (41.8%) of 79 women who received triple sulfonamide vaginal cream (P < 0.0001). Most of the difference between the treatment groups was noted in women with a history of bacterial vaginosis. Among women without a history of bacterial vaginosis, clindamycin and triple sulfonamide creams had similar efficacy. Evaluation of Gram-stained vaginal smears correlated with clinical outcome. Most patients in both treatment groups reported an improvement in symptoms. No significant difference was observed between the treatment groups in the incidence of adverse events. CONCLUSION: Clindamycin 2% vaginal cream is more effective than triple sulfonamide vaginal cream in the treatment of bacterial vaginosis.

Administration, Intravaginal↗

PubMed2000

Ion chromatographic analysis of tetracyclines using polymeric column and acidic eluent.

High-performance ion chromatography (HPIC) is first successfully used to analyze tetracycline antibiotics (TCs) in this work. The TCs are well separated on a solvent compatible polymeric cation-exchange column within 12 min. Isocratic elution with acetonitrile-hydrochloride is very advantageous for routine analysis. HPIC may be seen as a specific variant of the more common high-performance liquid chromatography (HPLC) for water-soluble and polar pharmaceuticals with low hydrophobicity. The detection limits (signal-to-noise ratio=3:1) of oxytetracycline (OTC), tetracycline (TC), chlortetracycline (CTC), doxycycline (DC) are 10, 10, 20 and 20 microg l(-1), respectively. Samples are prepared by vortex mixing with an ethylenediaminetetraacetic acid disodium salt (Na2EDTA)-McIlvaine buffer (pH 4.0) solution and the mixture filtrates through a molecular weight cut-off filter. The method has been successfully applied to monitor the OTC removal rate through every reactor in the process of OTC manufacturing wastewater treatment by bio-chemical technology. It is also applicable to determine the TCs residues in milk and milk powder with satisfying results.

Acids↗

PubMed1999

Use of ion chromatography for the determination of heavy and transition metals in biochemical samples.

A novel, highly sensitive method for simultaneous separation and determination of Cu2+, Ni2+, Zn2+, Cd2+, Co2+, Mn2+ and Pb2+ in biochemical samples was developed and evaluated by ion chromatography. All of these metals were well separated on a bifunctional ion-exchange column by a concentration gradient of oxalic acid and sodium chloride eluents, coupled with spectrophotometric detection after post-column derivatization with 2-[(5-bromo-2-pyridyl)azo]-5-diethylaminophenol at 560 nm. The method detection limits (signal-to-noise 3:1) were at microg l(-1) levels. The calibration graphs were linear (r2>0.999) over two-orders of magnitude. This technique was optimized and validated by analyzing five standard biochemical references.

Animals↗

PubMed1999

Signaling via Src family kinases is required for normal internalization of the receptor c-Kit.

Stem cell factor (SCF) exerts its biological effects by binding to a specific receptor, the tyrosine kinase c-Kit, which is expressed on the cell surface. Although normal cellular trafficking of growth factor receptors may play a critical role in the modulation of receptor function, the mechanisms that regulate the distribution of c-Kit on the cell surface and the internalization of c-Kit have not been fully defined. We investigated whether signal transduction via Src family kinases is required for normal c-Kit trafficking. Treatment of the SCF-responsive human hematopoietic cell line MO7e with the inhibitor of Src family kinases PP1 blocked SCF-induced capping of c-Kit and internalization of c-Kit. c-Kit was able to associate with clathrin in the presence of PP1, suggesting that entry of c-Kit into clathrin-coated pits occurs independently of Src family kinases. SCF-induced internalization of c-Kit was also diminished in the D33-3 lymphoid cell line in which expression of Lyn kinase was disrupted by homologous recombination. These results indicate that Src family kinases play a role in ligand-induced trafficking of c-Kit.

Cell Membrane↗

PubMed1999

Lyn is activated during late G1 of stem-cell-factor-induced cell cycle progression in haemopoietic cells.

Stem cell factor (SCF) binds the receptor tyrosine kinase c-Kit and is critical in haemopoiesis. Recently we found that the Src family member Lyn is highly expressed in SCF-responsive cells, associates with c-Kit and is activated within minutes of the addition of SCF. Here we show that SCF activates Lyn a second time, hours later, during SCF-induced cell cycle progression. In cells arrested at specific phases of the cell cycle with the drugs mimosine, aphidicolin and nocodazole, maximal Lyn kinase activity occurred in late G(1) and through the G(1)/S transition. Similarly, kinetic studies of SCF-induced cell cycle progression found that activation of Lyn preceded the G(1)/S transition and was maintained into early S-phase. Activation of Lyn was paralleled by two events critical for the G(1)/S transition, increases in cyclin-dependent kinase 2 (Cdk2) activity and phosphorylation of the retinoblastoma gene product (Rb). Lyn was associated with Cdk2; Cdk2-associated Lyn was heavily phosphorylated on serine and threonine residues both in vitro and in situ during S-phase. Inhibition of Lyn activity with PP1 disrupted association with Cdk2 and decreased the numbers of cells entering S-phase. The degree of phosphorylation of Rb in PP1-treated cells suggested an increased number of cells arrested in the middle of G(1). These findings demonstrate that SCF activates the Src family member Lyn before the G(1)/S transition of the cell cycle and suggest that Lyn is involved in SCF-induced cell cycle progression.

Aphidicolin↗

PubMed1999

[The determination of anions of very weak acids by incompletely suppressed conductometric detection].

A novel method, incompletely suppressed conductometric detection, has been developed for the determination of anions of very weak acids. The principle of the method is discussed. The advantages of the method over the suppressed and nonsupressed methods for the determination of anions of very weak acids are also discussed theoretically. Results showed that the detection limits of the method for arsenous acid and boric acid were lower than those of nonsuppressed conductometric method. Being compared with suppressed conductometric method, the sensitivity was improved greatly. For 250 mg/L boric acid, 261- and 1002-fold increases in peak height and peak area were obtained, respectively. Within the linear range of the detection, the linear correlation coefficients of the peak areas of two weak acids were 0.9991 and 0.9985, respectively.

Anions↗

PubMed1999

[Determination of inosine 5'-monophosphate and guanosine 5'-monophosphate in taste-enhancers by ion chromatography].

A high performance anion-exchange chromatographic method was developed for the simultaneous determination of two kinds of taste-enhancers, inosine 5'-monophosphate (IMP) and guanosine 5'-monophosphate (GMP), in the presence of monosodium glutamate and chloride (salt). The separation was achieved by using Dionex IonPac AG11 and IonPac AS11 columns, and the determination by ultraviolet absorbance detection at 254 nm. The detection limits (S/N = 3) were 0.21 mg/L and 0.27 mg/L for IMP and GMP, respectively. Good linearities between the concentrations of the two analytes and relevant peak area responses were obtained in the range of 2-100 mg/L. Under the experimental conditions, glutamate, chloride, succinate, benzoate, sorbic acid and citrate did not interfere in the determination of IMP and GMP. The method has been successfully applied to the determination of IMP and GMP in gourmet powder as well as chicken bouillon, and the average recoveries for various samples ranged from 97% to 103%.

Calibration↗

PubMed1999

[Liquid chromatography with amperometric detection].

Amperometric detection in liquid chromatography is introduced in this article. Detection mechanism and conditions involved in the application in HPLC and HPIC with d.c. amperometry, pulsed amperometry and integrated amperometry detection are discussed.

Chromatography, High Pressure Liquid↗

PubMed1998

On-line pretreatment and determination of Pb, Cu and Cd at the microgram l-1 level in drinking water by chelation ion chromatography.

A novel, highly sensitive method for the simultaneous separation and determination of lead, copper, cadmium and other transition metals in drinking water was achieved by on-line sample pretreatment of chelation ion chromatography. Manganese, which coeluted with cadmium, was oxidized to permanganate by ammonium persulfate before injection. Permanganate, with bulk quantity of alkali, alkaline earth metals, iron and aluminum, was eliminated by pyrophosphoric acid-ammonium acetate buffer solution (pH 5.5), while retaining heavy and transition metals on a selective chelating resin (MetPac CC-1 column). Then, they were disabsorbed and transferred to a sulfonated cation exchanger (TMC-1 column). Finally, the concentrated trace metals were separated on a bifunctional ion-exchange column (CS5A) by a concentration gradient of oxalic acid and sodium nitrate eluents, coupled with post-column spectrophotometric detection with 2-[(5-bromo-2-pyridyl)azo]-5-diethylaminophenol (5-Br-PADAP) at 560 nm. The separation and color-development conditions were optimized. The detection limits for the method (signal-to-noise ratio = 3:1) were at or below the microgram l-1 level. The results of drinking water analyses were satisfactory.

Cadmium↗

PubMed1998

[Study on the determination of trace metals in complex matrices by chelation ion chromatography].

In this paper, a new method for determination of trace metal ions in complex matrices by chelation ion chromatography has been developed. In accordance to different analysis purpose, different interference should be selectively eliminated. On the chelating resins, all anions, alkali and alkaline earth metals could be eluted by ammonium acetate eluent (pH 5.5), tervalent cations could be eluted by pyrophosphoric acid/ammonium acetate eluent (pH 5.5). On sulfonated cation exchanger, heavy metals, transition metals, iron and aluminum could be eluted by hydrochloric acid/ethanol and oxalic acid/nitric acid eluents. Then, the concentrated lanthanides and transition metals (Pb, Cu, Cd, Ni, Zn and Co) were separated on bifunctional ion-exchange ion-exchange column by a proper concentration gradient of eluents, coupled with post-column spectrophotometric detection. Test samples could be injected directly into the column for analysis after the sample digestion. The detection limits of the method (signal-to-noise = 3:1) were at or below microgram/L level. The method has been systematically applied in rock, alloy, soil, plant and animal samples.

Chelating Agents↗

PubMed1997

Lyn associates with the juxtamembrane region of c-Kit and is activated by stem cell factor in hematopoietic cell lines and normal progenitor cells.

Stem cell factor (SCF) is a cytokine critical for normal hematopoiesis. The receptor for SCF is c-Kit, a receptor tyrosine kinase. Our laboratory is interested in delineating critical components of the SCF signal transduction pathway in hematopoietic tissue. The present study examines activation of Src family members in response to SCF. Stimulation of cell lines as well as normal progenitor cells with SCF rapidly increased tyrosine phosphorylation of the Src family member Lyn. Peak responses were noted 10-20 min after SCF treatment, and phosphorylation of Lyn returned to basal levels 60-90 min after stimulation. SCF also induced increases in Lyn kinase activity in vitro. Lyn coimmunoprecipitated with c-Kit, and studies with GST fusion proteins demonstrated that Lyn readily associated with the juxtamembrane region of c-Kit. Treatment of cells with either Lyn antisense oligonucleotides or PP1, a Src family inhibitor, resulted in dramatic inhibition of SCF-induced proliferation. These data demonstrate that SCF rapidly activates Lyn and suggest that Lyn is critical in SCF-induced proliferation in hematopoietic cells.

Binding Sites↗

PubMed1997

Stat1 associates with c-kit and is activated in response to stem cell factor.

Interaction of stem cell factor (SCF), a haematopoietic growth factor, with the receptor tyrosine kinase c-kit leads to autophosphorylation of c-kit as well as tyrosine phosphorylation of various substrates. Little is known about the role of the JAK/STAT pathway in signal transduction via receptor tyrosine kinases, although this pathway has been well characterized in cytokine receptor signal transduction. We recently found that the Janus kinase Jak2 associates with c-kit and that SCF induces rapid and transient phosphorylation of Jak2. Here we present evidence that SCF activates the transcription factor Stat1. Phosphorylated c-kit co-immunoprecipitates with Stat1 within 1 min of SCF stimulation of the human cell line MO7e. Co-precipitation experiments using glutathione S-transferase fusion proteins indicate that association with c-kit is mediated by the Stat1 SH2 domain. Stat1 is rapidly tyrosine-phosphorylated in response to SCF in MO7e cells, the murine cell line FDCP-1 and normal progenitor cells. SCF-induced phosphorylation of Jak2 and Stat1 was also observed in murine 3T3 fibroblasts stably transfected with full-length human c-kit receptor. Furthermore c-kit directly phosphorylates Stat1 fusion proteins in in vitro kinase assays. Electrophoretic mobility-shift assays with nuclear extracts from SCF-stimulated cell lines and normal progenitor cells indicate that activated Stat1 binds the m67 oligonucleotide, a high-affinity SIE promoter sequence. These results demonstrate that Stat1 is activated in response to SCF, and suggest that Stat1 is a component of the SCF signal-transduction pathway.

Animals↗

PubMed1997

Mortality in Chicago attributed to the July 1995 heat wave.

OBJECTIVES: This study assessed mortality associated with the mid-July 1995 heat wave in Chicago. METHODS: Analyses focused on heat-related deaths, as designated by the medical examiner, and on the number of excess deaths. RESULTS: In July 1995, there were 514 heat-related deaths and 696 excess deaths. People 65 years of age or older were overrepresented and Hispanic people underrepresented. During the most intense heat (July 14 through 20), there were 485 heat-related deaths and 739 excess deaths. CONCLUSIONS: The methods used here provide insight into the great impact of the Chicago heat wave on selected populations, but the lack of methodological standards makes comparisons across geographical areas problematic.

Age Distribution↗

PubMed1997

Stem cell factor, the JAK-STAT pathway and signal transduction.

Recent work has demonstrated the importance of Janus family kinases (JAKs) and signal transducers and activators of transcription (STATs) in the stimulus-response coupling of receptors lacking intrinsic tyrosine kinase activity. In particular, the JAK-STAT pathway appears critical in signal transduction by interferon as well as numerous hematopoietic growth factors interacting with members of the hemapoietin receptor superfamily. Although ligands that interact with receptor tyrosine kinases (RTK), such as epidermal growth factor (EGF), platelet-derived growth factor (PDGF) and colony stimulating factor-1 (CSF-1), have been shown to induce increases in phosphorylation of both JAKs and STATs, little is known about activation of this pathway by stem cell factor (SCF). This review will summarize what is known about the JAK/STAT pathway in relation to SCF signal transduction.

Animals↗

PubMed1997

[Study on the analysis of organogermanium compounds by ion chromatography].

A new high performance ion exchange chromatographic method for separation and determination of three organogermanium compounds beta-carboxyethylgermanium sesquioxide (I), beta-(alpha-methyl) carboxyethylgermanium sesquioxide (II) and di-(beta-carboxyethyl) germanium hydroxide (III) has been developed. A Dionex DX-300 Ion Chromatograph equipped with a Dionex PED-II pulsed electrochemical detector (conductivity mode), a Dionex AMMS-1 anion micromembrane suppressor, and a Dionex ACI advanced computer interface coupled with AI-450 chromatographic software was employed. The separation was achieved by using a Dionex IonPac AS4A-SC column as analytical column, sodium tetraborate solution as eluent, and sulfuric acid solution as regenerant. For reducing run time, a gradient program was chosen. The detection limits (S/N = 3, expressed as germanium) for the three compounds were 0.038mg/L (I), 0.035mg/L (II) and 0.025mg/L (III), respectively. The method has been applied to the analysis of two tonic oral drinks, and the average recoveries for the three compounds ranged from 95%-101%. The results obtained were in agreement with those of hydride generation atomic fluorescence spectrometry (HG-AFS).

Chromatography, Ion Exchange↗