PubMed Health⌕ Search

Biomedical subjects

Y Han

Publications and source records attributed to Y Han.

At least 91 records · Page 5Linked to original sources
PubMed2001

Response surface modeling for the inactivation of Escherichia coli O157:H7 on green peppers (Capsicum annuum L.) by chlorine dioxide gas treatments.

The effects of chlorine dioxide (ClO2) gas concentration (0.1 to 0.5 mg/liter), relative humidity (RH) (55 to 95%), treatment time (7 to 135 min), and temperature (5 to 25 degrees C) on inactivation of Escherichia coli O157:H7 on green peppers were studied using response surface methods. A four-factor, central, composite, rotatable design was used. The microbial log reduction was measured as a response. A direct membrane-surface-plating method with tryptic soy agar and sorbitol MacConkey agar was used to resuscitate and enumerate ClO2-treated E. coli O157:H7 cells. The statistical analysis and the predictive model developed in this study suggest that ClO2 gas concentration, treatment time, RH, and temperature all significantly (P < 0.01) increased the inactivation of E. coli O157:H7. ClO2 gas concentration was the most important factor, whereas temperature was the least significant. The interaction between ClO2 gas concentration and RH indicated a synergistic effect. The predictive model was validated, and it could be used to determine effective ClO2 gas treatments to achieve a 5-log reduction of E. coli O157:H7 on green peppers.

Capsicum↗
PubMed2001

[Effect of LAS on physico-chemical properties and microorganism activity in soil environment].

Using a well drained paddy soil and the derived soil under vegetables in the Taihu Lake region, China, experiments of soil capillary rise, colloid dispersion and adsorption of toxic organics and heavy metals by soil under various degrees of LAS addition were conducted. Also incubation experiments of microorganism activity in soil with added LAS in different concentrations were carried out in laboratory. LAS addition resulted in lower capillary rise of soil solution, higher dispersion of soil colloids and lower capacity of soil for organic pollutants but no significant influence on adsorption of heavy metal cations. The nitrification and amonification in soil were very sensitive to LAS stress while denitrification turned to be stimulated. LAS addition gave stronger growth of soil bacteria while decreased growth of fungus. Meanwhile, soil respiration was stimulated in the first week of incubation and compressed afterwards by LAS at concentration over 5 mg/kg. It seemed that some species of microorganisms were tolerant of LAS in the studied soils.

Alkanesulfonic Acids↗
PubMed2001

[Clinical and pathological study of autoimmune hepatopathy].

OBJECTIVE: To study the clinical and histologic characteristics of autoimmune hepatopathy, and to explore the diagnostic criteria and therapy. METHODS: Sixty-two patients with autoimmune hepatopathy were studied between 1996 and 1998 to compare primary biliary cirrhosis (PBC) and autoimmune hepatitis (AIH) in the clinical symptoms, signs, laboratory findings and histologic features. RESULTS: PBC was 59.68% and AIH 40.32% in the autoimmune hepatopathy. The morbidity in middle and old aged female patients with autoimmune hepatopathy was 83.8%. The ratio of male and female was 1:10. Whereas, the ratio of male and female was 1:5 in AIH patients and average age was 35 years old. Seropositive autoimmune antibodies were detected in 53 serum sample (PBC 85.29%; AIH 78.95%). Positive rates of the mitochondrial antibody and subtype-M2 were 100% for PBC. IgM increasing was 80% in PBC (P<0.05) and 82.35% in AIH (P<0.025). Histologic features in PBC group consisted of cholangitis, destruction or proliferation of the bile duct and inflammation within the portal tract; while in AIH group inflammation, necrosis and fibrosis of periportal region, the aggregation of lymphocytes, mononuclear cells and plasma cells in the portal tract or periportal area were found. CONCLUSIONS: PBC and AIH are the most common two types in the patients with autoimmune hepatopathy. AIH-I is more often seen clinically. AMA-M2 is the special autoimmune antibody of PBC. The efficacy of prednisolone is better for AIH than PBC.

Adult↗
PubMed2001

[The effect of p53 gene on p-glycoprotein expression and chemotherapeutic cytotoxicity of hepatocellular carcinoma].

OBJECTIVE: To test the hypothesis that wild-type p53 regulates the expression of p-glycoprotein. METHODS: Hep3B cells which lack the expression of both p53 and retinoblastoma tumor suppressor genes because of deletions, were transfected with a wild-type (wt) p53 cDNA and control vector by a liposome method. RESULTS: After G418 selection, stable wt-p53 transformants and control vector transformants (pNeo) were obtained. Northern and Western blot analysis determined the expression of p53 mRNA and protein in wt-p53 transformants, respectively. In wt-p53 transformants, induction of transcriptionally active p53 was confirmed by the increase of P21(waf1/cip1) protein. Levels of P-gp reduced in the cells expressing wild-type p53 were linked to wt-p53 activity. Cytotoxicity assays revealed that the wt-p53 transfectants were more sensitive to doxorubicin and mitomycin compared with the pNeo transformants. Flow cytometry showed that the accumulation of doxorubicin in wt-p53 transfectants was as 13 times as that of the pNeo transformants. CONCLUSIONS: Restoration of wt-p53 activity in Hep3B leads to sensitiveness to chemotherapeutic agents because of the decrease of p-glycoprotein expression.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

[Rat keratinocyte primary cultures based on conductive polypyrrole primary cell culture technique].

Orthogonal experimental design has been applied to study the suitable cell culture medium and condition of conductive polypyrrole on rat keratinocyte cell cultures. The results showed that one thousand milliliters of complete minimum essential medium(CMEM) which contained 900 ml minimum essential medium(MEM), 10% fetal bovine serum(FBS), 1% NEAA, 6 ml insulin and 10 mg hydrocortisone was fit for keratinocyte cell culture. And the conductive polypyrrole obtained with 10 mA current density for 100 second switching times, given 100 mV electrical stimulation voltage for 2 hours, would stimulate the growth of rat keratinocyte cell in vitro cultures. The cell density under culture conditions described above was 1.30 times as high as that under routine culture conditions.

Animals↗
PubMed2001

[A novel point mutation in the transmembrane domain of platelet glycoprotein IX gene identified in a Bernard-Soulier syndrome patient].

OBJECTIVE: To diagnose a patient with Bernard-Soulier syndrome (BSS) and investigate her gene abnormality. METHODS: Platelet size and structure were studied under light and electron microscopies. Platelet membrane glycoproteins (GP) were measured by flow cytometry. PCR and DNA sequencing were used to identify gene abnormality. RESULTS: The patient had thrombocytopenia with giant platelets. Ristocetin-induced platelet agglutination was absent. GP I b/IX complex in the platelet membrane was significantly decreased, which was resulted from an Ala139 Thr substitution in the transmembrane domain of GPIX. CONCLUSION: Ala139 Thr mutation of the GPIX gene in this patient is a novel missense mutation, which has not been reported in BSS.

Adult↗
PubMed2001

[Expression and function of protein kinase C-alpha and beta I isoenzymes in drug-resistant gastric cancer cells].

OBJECTIVE: To study the expression and function of PKC-alpha and beta I isoenzymes in drug-resistant cells of gastric cancer. METHODS: Two tumor cell lines were used in the study: gastric cancer SGC7901 and its drug-resistant counterpart SGC7901/VCR stepwise-selected by various concentrations of vincristine. The expression of PKC-alpha and beta I isoenzymes in SGC7901 and SGC7901/VCR was detected by immunohistochemistry, laser confocal scanning microscopy and Western blot. The effects of anti-PKC-alpha or beta I antibody on adriamycin accumulation in SGC7901/VCR cells were determined by flow cytometric analysis. RESULTS: SGC7901 cells exhibited positive staining of PKC-alpha. The staining of PKC-alpha in SGC7901/VCR was stronger than that in SGC7901 cells. The higher the concentrations of vincristine, the stronger staining of PKC-alpha was observed on SGC7901/VCR cells. Both SGC7901 and SGC7901/VCR cells were positive for PKC-beta I, but without difference in staining intensity. Comparing with SGC7901, SGC7901/VCR cells showed decreased adriamycin accumulation; the decrease was more marked with the increase in concentrations of vincristine for selection of cells. Increased adriamycin accumulation in SGC7901/VCR was observed when co-incubated with anti-PKC-alpha but not anti-PKC-beta I antibodies. CONCLUSION: PKC-alpha may play a role in multidrug resistance of gastric cancer cells SGC7901/VCR.

Blotting, Western↗
PubMed2001

[Detection and diagnosis of small peripheral lung cancers less than 15 mm in diameter].

OBJECTIVE: To assess the value of chest film, conventional CT (CCT), Spiral CT (SCT) and high resolution CT (HRCT) for detection and diagnosis of small peripheral lung cancers less than 15 mm in diameter. METHODS: Chest film, CCT, SCT and HRCT were taken in 59 cases of peripheral lung cancers less than 15 mm in diameter confirmed by operation and pathology. Their value in the diagnosis was analysed retrospectively. RESULTS: In 47% of chest films and 17% of CCT, the small lung cancer was not detected. However no tumor escaped detection by SCT. HRCT was superior for showing density and detailed image signs compared to chest film and CCT. The CT features of small peripheral lung cancers was different from those of larger peripheral lung cancers. CONCLUSION: The SCT is the best method for detection, and HRCT for diagnosis of small peripheral lung cancers less than 15 mm in diameter.

Adult↗
PubMed2001

[A clinical investigation on the relationship between nitric oxide and elevation of intraocular pressure in glaucoma].

OBJECTIVE: To investigate the role of nitric oxide (NO) in the process of intraocular pressure (IOP) elevation in glaucoma. METHODS: The levels of NO in plasma and in aqueous humor which were obtained from 16 patients with acute angle closure glaucoma (10 female, 6 male), 29 cases with cataract (13 female, 16 male) and 30 normal volunteers (13 female, 17 male) were detected by high performance liquid chromatography and expressed with the total NO(2) and NO(3). RESULTS: It was found that the mean level of NO in the plasma in glaucoma group was (l,390.78 +/- 302.95) ng/L that was significantly lower than that in the normal group (2 969.37 +/- 862.85) ng/L (t = 2.853, P < 0.01). But in cataract group it was (4,234.89 +/- 1,495.23) ng/L that was significantly higher than that in the normal group (t = 4.471, P < 0.01). There was no significant difference in the level of NO in the aqueous humor between glaucoma group (2,052.03 +/- 694.74) ng/L and normal group (1,405.83 +/- 602.70) ng/L (t = l.862, P > 0.05). But in cataract group the mean level of NO (2, 454.67 +/- 655.13) ng/L in the aqueous humor was increased remarkably in comparison with that in the normal group (t = 2.752, P < 0.01). The rate of the mean content of NO in normal aqueous humor and plasma (aqueous/plasma) was 47.3%, and that in cataract group, 57.96% (P > 0.05). But in glaucoma group, the rate was 144.0%. CONCLUSION: The content of nitric oxide in the plasma and aqueous humor is related to the elevation of IOP in cases with acute angle closure glaucoma.

Aged↗
PubMed2001

[Study of bone mineral density measuring system with quantitative CT].

This paper introduces a kind of bone mineral density(BMD) measuring system with quantitative CT(QCT). This system includes a self-made solid calibration phantom for BMD and the measuring software. The results of the tests have showed that this system is reliable, cheap and ease of use for BMD measurement.

Absorptiometry, Photon↗
PubMed2001

[The reconstruction of laryngeal function in subtotal laryngectomy by pedicled flaps].

OBJECTIVE: To explore the possibility of subtotal laryngectomy in the treatment of advanced laryngeal cancer and selection of reconstruction. METHODS: Forty patients were treated surgically by subtotal laryngectomy with preservation of arytenoid cartilage and perichondrium. The pedicled flaps between cricoid cartilage and arytenoid cartilage were sewed up. The new larynx was reconstructed by suturing the cricoid or trachea to the hyoid bone or the tongue base. RESULTS: The 3 and 5 year survival rates were 85.0% and 76.2% respectively. Decannulation rate was 92.5%. CONCLUSION: The reconstruction of laryngeal function in subtotal laryngectomy by pedicled flaps not only is safe and beneficial to the patients with the cancers above the cricoid, but also improves the quality of patient's life.

Adult↗
PubMed2000

Cloning and expression of MP13 gene from rat hippocampus, a new factor related to guanosine triphosphate regulation.

C-Fos and the Fos-related antigens (FRA) are induced by various stimuli. A novel 35-37 kDa FRA was induced much longer after the treatment using kainic acid (KA) and may be very important for neuronal survival after brain damage. To identify this long-term FRA, we have constructed a cDNA library derived from hippocampus after KA treatment and screened it with an antibody highly conserved M-peptide region of FRAs. One gene, MP13, was cloned with a 1662 bp open reading frame and coded for a 554-amino acid protein. MP13 has a leucine zipper region, a glutamine repeat region, and has high similarity to the activator of the small guanosine triphosphate (GTP)ase Rab5. Gel retardation analysis revealed that MP13 functions as a GTP regulation related factor.

Amino Acid Sequence↗
PubMed2000

Differences of four catechins in cell cycle arrest and induction of apoptosis in LoVo cells.

(-)-Epigallocatechin-3-gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin-3-gallate (ECG), and (-)-epicatechin (EC) were found to have different cytotoxicities to human colon carcinoma LoVo cells. EGCG and EGC suppressed the growth of LoVo cells in dose-dependent manner; ECG and EC, however, had no obvious effects. At lower concentrations, EC did seem to promote slight proliferation. Similarly, EGCG and EGC, rather than ECG and EC, were found to induce apoptosis in LoVo cells. Moreover, EGCG, EGC, and ECG arrested G(1) phase in the cell cycle progression, whereas EC resulted in S phase arrest. We suggest that there are differences in the cytotoxicities of the four catechins to LoVo cells. They exert the effects by inducing apoptosis and regulating the cell cycle.

Apoptosis↗
PubMed2000

Morphological and electrophysiological properties of dissociated primate retinal cells.

Although isolated retinal cell preparations have been used widely to study retinal function in lower vertebrates, dissociated cells from primate retina have not been developed for routine physiological experiments. In this study, we demonstrated the feasibility of obtaining viable and identifiable dissociated cells from the primate retina. In addition, we characterized voltage-dependent membrane currents in each type of primate retinal cell with the whole-cell patch-clamp technique. Multiple types of ionic conductance with distinctive current profiles were recorded in various types of primate retinal neurons. Photoreceptors exhibited an inward I(H) activated by membrane hyperpolarization and an outward current activated at depolarized potentials. Two types of potassium currents (transient potassium current, I(K(A)), and delayed rectifier potassium current, I(K(V))) were recorded from bipolar cells. I(K(A)) dominated the current response in putative midget bipolar cells, and I(K(V)) was mainly associated with putative rod bipolar cells. L-type calcium currents (I(Ca)) were observed in primate bipolar cells with axon terminals, but not in axotomized bipolar cells. Large voltage-dependent sodium currents (I(Na)) were only recorded from ganglion cells. Muller cells exhibited I(K(V)) and large potassium inward rectifier current (I(K(IR))), and occasionally a small I(Na). Neurons with electrophysiological signatures of amacrine cells and horizontal cells were also studied even though their morphological features were lost during cell dissociation. By using both morphological and physiological criteria outlined in this report, it is possible to use the dissociated retinal cell preparation as an in vitro system for physiological, biochemical and pharmacological studies of the primate visual system.

Amacrine Cells↗
PubMed2000

Protection against ischemic injury in primary cultured mouse astrocytes by bis(7)-tacrine, a novel acetylcholinesterase inhibitor [corrected].

The effects of bis(7)-tacrine, a novel acetylcholinesterase inhibitor, on ischemia-induced cell death and apoptosis were investigated in primary cerebral cortical astrocytes of mice. Following a 6 h in vitro ischemic incubation of the cultures, a marked decrease in the percentage of viable cells was observed by lactate dehydrogenase (LDH) release assay. Furthermore, using bisbenzimide staining, we determined that approximately 65% of the cells underwent apoptosis. Treatment with bis(7)-tacrine (1-10 nM) during ischemic incubation effectively inhibited the ischemia-induced apoptosis, as demonstrated by morphological and biochemical tests. Our results demonstrated that bis(7)-tacrine could protect astrocytes against ischemia-induced cell injury, indicating that the drug might be beneficial for the treatment of vascular dementia, in addition to Alzheimer's disease.

Alzheimer Disease↗
PubMed2000

Conformational difference between PDE4 apoenzyme and holoenzyme.

The type 4 cAMP-specific phosphodiesterases (PDE4s) are Mg(2+)-dependent hydrolases that catalyze the hydrolysis of 3', 5'-cAMP to AMP. Previous studies indicate that PDE4 exists in two conformations that bind the inhibitor rolipram with affinities differing by more than 100-fold. Here we report that these two conformations are the consequence of PDE4 binding to its metal cofactor such as Mg(2+). Using a fluorescence resonance energy transfer (FRET)-based equilibrium binding assay, we identified that L-791,760, a fluorescent inhibitor, binds to the apoenzyme (free enzyme) and the holoenzyme (enzyme bound to Mg(2+)) with comparable affinities (K(d) approximately 30 nM). By measuring the displacement of the bound L-791,760, we have also identified that other inhibitors bind differentially with the apoenzyme and the holoenzyme depending upon their structure. CDP-840, SB-207499, and RP-73401 bind preferentially to the holoenzyme. The conformational-sensitive inhibitor (R)-rolipram binds to the holoenzyme and apoenzyme with affinities (K(d)) of 5 and 300 nM, respectively. In contrast to its high affinity (K(d) approximately 2 microM) and active holoenzyme complex, cAMP binds to the apoenzyme nonproductively with a reduced affinity (K(d) approximately 170 microM). These results demonstrate that cofactor binding to PDE4 is responsible for eliciting its high-affinity interaction with cAMP and the activation of catalysis.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2000

Formation of surface tubules and fluorescent foci in Arabidopsis thaliana protoplasts expressing a fusion between the green fluorescent protein and the cauliflower mosaic virus movement protein.

The movement protein (MP) of cauliflower mosaic virus (CaMV) is a multifunctional protein that potentiates the cell-to-cell and long distance movement of the virus. Functional domains in the CaMV MP were determined by analyzing deletions in green fluorescent protein (GFP)-MP fusions transfected into Arabidopsis thaliana leaf protoplasts. GFP-MP accumulated at fluorescent foci at the cell periphery and in tubular structures extending from the protoplast surface. A region located near the center of MP was required for targeting GFP-MP to foci, whereas a larger region extending nearly to the N-terminus was needed for tubule formation. Cytoskeletal assembly inhibitors did not disrupt tubule formation or the accumulation of GFP-MP at foci, but brefeldin A, which disrupts the plant cell endomembrane system, did interfere with the formation of tubules but not foci.

Antiviral Agents↗