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Biomedical subjects

X Shi

Publications and source records attributed to X Shi.

At least 217 records · Page 12Linked to original sources
PubMed1999

Critical role of glass fiber length in TNF-alpha production and transcription factor activation in macrophages.

Recent studies have demonstrated that dielectrophoresis is an efficient method for the separation of fibers according to fiber length. This method allows the investigation of fiber-cell interactions with fiber samples of the same composition but of different lengths. In the present study, we analyzed the effects of length on the interaction between glass fibers and macrophages by focusing on production of the inflammatory cytokine tumor necrosis factor (TNF)-alpha in a mouse macrophage cell line (RAW 264.7). The underlying molecular mechanisms controlling TNF-alpha production were investigated at the gene transcription level. The results show that glass fibers induced TNF-alpha production in macrophages and that this induction was associated with activation of the gene promoter. Activation of the transcription factor nuclear factor (NF)-kappaB was responsible for this induced promoter activity. The inhibition of both TNF-alpha production and NF-kappaB activation by N-acetyl-L-cysteine, an antioxidant, indicates that generation of oxidants may contribute to the induction of this cytokine and activation of this transcription factor by glass fibers. Long fibers (17 micrometer) were significantly more potent than short fibers (7 micrometer) in inducing NF-kappaB activation, the gene promoter activity, and the production of TNF-alpha. This fiber length-dependent difference in the stimulatory potency correlated with the fact that macrophages were able to completely engulf short glass fibers, whereas phagocytosis of long glass fibers was incomplete. These results suggest that fiber length plays a critical role in the potential pathogenicity of glass fibers.

Acetylcysteine↗
PubMed1999

Detection of high-intensity focused ultrasound liver lesions using dynamic elastometry.

A novel ultrasound technique was developed for detecting the distribution of stiffness in biological tissue. The method, which we call 'dynamic elastometry,' involves applying a low-frequency vibration (< or = 5 Hz) to the tissue and measuring the resulting velocity pattern within the sample using Doppler spectral analysis. Based upon the velocity differences, an elastically stiff region can be differentiated from surrounding soft tissue. Dynamic elastometry was used to both detect and quantify lesions produced by high-intensity focused ultrasound (HIFU) in porcine livers. Measurements of the lesion position and length agreed well with independent geometric measurements. The mean and standard deviation of the differences between the two types of measurement were -0.01 cm and 0.10 cm for lesion position, and -0.05 cm and 0.12 cm for lesion length, respectively. The relative stiffness between lesions and normal liver tissue was estimated by the velocity gradient ratio. Results were compared with the Young's modulus ratios between lesion and normal liver tissue obtained from mechanical measurement. The dynamic elastometric estimates had a strong linear correlation with the mechanical measurements (r = 0.93) but were smaller than the latter by 26%.

Animals↗
PubMed1999

Scavenging of superoxide anion radical by chaparral.

Chaparral is considered to act as an antioxidant. However, the inhibitory effects of chaparral on specific radical species are not well understood. Using electron paramagnetic resonance (EPR) spectroscopy in combination with spin trapping techniques, we have found that chaparral scavenges superoxide anion radical (O2*-) in a dose-dependent manner. 5,5-dimethyl-lpyrroline-N-oxide (DMPO) was used as a spin trapping agent and the reaction of xanthine and xanthine oxidase as a source of O2*-. The kinetic parameters, IC50 and Vmax, for chaparral scavenging of O2*- were found to be 0.899 microg/mL and 8.4 ng/mL/sec, respectively. The rate constant for chaparral scavenging O2*- was found to be 1.22 x 10(6) g(-1) s(-1). Our studies suggest that the antioxidant properties of chaparral may involve a direct scavenging effect of the primary oxygen radical, O2*-.

Electron Spin Resonance Spectroscopy↗
PubMed1999

Redox-dependent regulation of interleukin-8 by tumor necrosis factor-alpha in lung epithelial cells.

Increasing evidence supports a major role for interleukin-8 (IL-8), a potent neutrophil chemoattractant, in the chronic progression of inflammatory lung diseases. The present studies were designed to characterize the molecular events involved in IL-8 induction in pulmonary epithelial cells in response to tumor necrosis factor-alpha (TNF-alpha). IL-8 induction by TNF-alpha was redox sensitive, as indicated by electron spin resonance analysis and inhibition with membrane permeable hydroxyl scavengers. Furthermore using cell transfection and mobility shift assays, it was found that transcriptional activation of the IL-8 gene required TNF-alpha-induced activation and binding of nuclear factor-kappaB (NF-kappaB)- and NF-IL-6, nuclear transcription factors to regulatory elements in the IL-8 promoter. Activation of the IL-8 promoter by these transcription factors was also redox-sensitive. This response was mediated through the TNF-R1 receptor (p55), and not the TNF-R2 (p75) receptor, although both receptors can be found on pulmonary epithelial cells. Taken together these studies indicate that TNF-alpha-induced redox changes in lung epithelial cells are responsible for the transcriptional activation of IL-8 and that coordinate activation of NF-kappaB and NF-IL-6 mediate the response.

Antigens, CD↗
PubMed1999

Detection of cyclophosphamide-induced mutations at the Hprt but not the lacI locus in splenic lymphocytes of exposed mice.

The relative sensitivities and specificities of the endogenous Hprt gene and the lacI transgene as mutational targets were evaluated in splenic lymphocytes from male standard B6C3F1 mice (only Hprt assayed) and from lacI transgenic B6C3F1 mice treated at 6-7 weeks- of-age with the indirect-acting agent, cyclophosphamide (CP). To define the effects of the time elapsed since CP treatment on Hprt mutant frequencies (Mfs), nontransgenic mice were given single i.p. injections of 25 mg CP/kg or vehicle (PBS) alone and then necropsied 2, 4, 6, 8, or 10 weeks after treatment. Peak Mfs were found at 6 weeks postexposure, with mean Mf values ranging from 2.27 to 3.27 x 10(-5) using two different lots of CP in standard packaging (compared with mean control Mf values of 0.14 to 0.26 x 10(-5) in various experiments). To determine the dose response for Hprt Mfs, nontransgenic mice were given single doses of 0, 12.5, 25, 50, or 100 mg CP/kg and necropsied 4 weeks postexposure. These treatments produced a supralinear dose response curve for CP-induced Hprt Mfs. Based on these experiments, CP mutagenicities at Hprt and lacI were compared in transgenic mice treated with 0, 25, or 100 mg CP/kg (using another lot of CP in ISOPAC((R)) bottles; Sigma) and necropsied 6 weeks later. There was a significant increase in Hprt Mfs in treated transgenic mice (100 mg CP/kg: 0.75 +/- 0.09 x 10(-5); 25 mg CP/kg: 0.39 +/- 0.05 x 10(-5)) versus controls (0.10 +/- 0.01 x 10(-5)); however, the Mfs in lacI of lymphocytes from the same CP-treated animals were not significantly different from controls (100 mg CP/kg: 9.4 +/- 1.1 x 10(-5); 25 mg CP/kg: 6.7 +/- 0. 8 x 10(-5); control: 7.7 +/- 0.7 x 10(-5)). Hprt mutational spectra data in CP-treated transgenic and nontransgenic mice were different from those of control mice, whereas the spectra of mutations in lacI of lymphocytes from Big Blue((R)) transgenic mice were not significantly changed after CP treatment. These data indicate that, under these treatment conditions, CP-induced mutations in splenic lymphocytes were detectable in the Hprt gene but not the lacI transgene of this nontarget tissue for CP-induced cancer.

Animals↗
PubMed1999

Insecticidal activity of transgenic tobacco plants expressing both Bt and CpTI genes on cotton bollworm (Helicoverpa armigera).

Transgenic tobacco plants expressing both Bacillus thuringiensis (Bt) insecticidal protein and cowpea trypsin inhibitor (CpTI) genes was used to evaluate the insecticidal activity on the cotton bollworm (Helicoverpa armigera) compared with transgenic tobacco with Bt insecticidal protein gene alone. Mortality of first to third instar larvae fed on transgenic two genes tobacco for three days was significantly higher than that fed on transgenic Bt tobacco. First to fourth instar larvae fed on transgenic two genes tobacco continuously could not survive until pupation. Second instar larvae were fed on transgenic tobacco plants for three days and then were transferred to an artificial diet. The efficacy of transgenic two genes tobacco on mortality, larvae weight, percentage of pupation, and time to pupation were significantly higher than that of transgenic tobacco with Bt insecticidal protein gene alone. The results with transgenic tobacco as model plant were valuable for other crops both for the enhancement of insecticidal efficacy and for the delay of insect adaptation to transgenic Bt crops.

Animals↗
PubMed1999

Subgingival access and artificial plaque removal by a sonic cleaning device.

A sonic subgingival cleaning device (soniPick Sonic Interdental Plaque Remover) has recently been marketed with three bristle tips varying in size lengths and bundle diameters. The purpose of this study was to evaluate the ability of these bristle tips to remove subgingival artificial plaque deposits in a laboratory method used for toothbrushes. The laboratory method has been modified for testing the sonic device, to simulate the directions for using the product at home. The dimensions (length x bundle width) of three tips tested were: 0.007" x 0.040"; 0.007" x 0.062"; and 0.009" x 0.062". The tips used with the sonic device were placed on the tooth surface at a 20 degrees angle according to directions, and inserted 3 mm under simulated gingivae. The device was turned on and the tip was moved in a maximum 10 mm stroke for 15 seconds with the brushing machine. For control purposes, a flat, multi-tufted, ADA-accepted manual toothbrush (Oral-B P35) was also tested. The manual toothbrush was tested using the standard methods for evaluating toothbrushes, i.e., with the bristle tips placed at the gingival margin, then brushed at a 45 degrees angle at 250 g weight, using 15 mm strokes for 60 seconds. The depth of subgingival deposit removal was recorded as the maximum depth of the artificial plaque deposit removed from the pressure-sensitive paper under the simulated gingivae over anterior- or posterior-shaped teeth. In the assays conducted, the three bristle tips on the sonic device removed artificial plaque deposits under the simulated gingival at depths of 1.9-2.7 mm. The manual toothbrush had a mean subgingival cleaning depth of 0.6 mm. Differences between the three bristle tips used with the sonic device and the manual toothbrush were significant (p < 0.001 ANOVA). In this laboratory assay, all 3 bristle tips provided with the sonic cleaning device maintained access into and subsequent removal of artificial plaque from the subgingival space.

Analysis of Variance↗
PubMed1999

Expression of leukocyte adhesion molecules CD11b, L-selectin and CD45 during hemodialysis.

OBJECTIVE: To examine the gene and protein expression of CD11b, L-selectin and CD45, and the relationship between their expression and leukocytopenia during a hemodialysis session. METHODS: Ten maintenance hemodialysis patients, 20 uremic non-dialysis patients and 10 healthy volunteers were included in this study. The mRNA expression of CD11b, L-selectin and CD45 in peripheral blood mononuclear cells was detected by RT-PCR, while cell surface expression of these molecules on monocytes was detected by flow cytometry and leukocyte number was counted manually. RESULTS: After the start of dialysis, both mRNA expression and cell surface expression of CD11b increased rapidly, while those of L-selectin and leukocyte number fell. The mRNA expression of CD45 first decreased and the cell surface expression increased, followed by a return to pre-dialysis levels, by the end of dialysis. CONCLUSIONS: Hemodialysis using a cuprophane membrane can induce rapid upregulation of CD11b and down-regulation of L-selectin, which might influence the normal adhesion and anti-inflammatory response of leukocytes. In this process CD45 may play a role in regulating and/or transducing activation signal.

Adult↗
PubMed1999

[Experimental studies on improving heart preservation effect of Astragalus saponins].

OBJECTIVE: To observe the effect of heart preservation of Astragalus saponins (AS) in modified Euro-Collins solution (mEC) containing AS. METHODS: Wistar rats were randomly divided into mEC and AS group. After preserving isolated rat hearts 6 hours by simple cold storage with mEC and mEC containing AS respectively, Langendorff's isolated rat heart model was used to reperfuse for 30 minutes to study cardiac function after preservation and the effect of preventing oxygen free radical injury. RESULTS: To compare AS group with mEC group, cardiac function and coronary flow of the hearts after preservation were better than mEC group (P < 0.05), in AS group the water content of myocardium was decreased very significantly (P < 0.01), myocardial lactate dehydrogenase and creatine phosphokinase release were reduced greatly (P < 0.05 and P < 0.01), myocardial superoxide dismutase activity was increased very significantly (P < 0.01) and the content of lipid peroxide was decreased significantly (P < 0.05). CONCLUSION: AS could improve the effect of heart preservation of mEC solution, its mechanism might be associated with the effect of negative contractile strength and preventing oxygen free radical injury.

Animals↗
PubMed1999

[Total removal of craniopharyngioma].

OBJECTIVE: To study the better method of surgical management of craniopharygioma. METHODS: We treated 30 patients with craniopharyngioma ranged in age from 15 to 55 years (mean: 34.13 years old). MR image showed that the tumors' diameter varied from 2.0 cm to 6.0 cm (mean, 3.34 cm). 17 patients had the tumor in suprasellar region, 11 had tumor extension in the third ventricle 2 and had the tumor down to insellar. Complete cystic tumor was seen in 5 patients, partial cystic tumor in 17, and solid tumor in 8. Calcified tumor was found in 18 patients. Frontal temporal craniotomy was performed in all patients. The tumor was dissected in the parachiasmal opticocarotid, carotidotentorial spaces and lamina terminals. Great attention was paid to the preservation of the perforating arteries from the carotid, posterior and anterior communication and anterior choroidal arteries to the structure of the hypothalamus. The solid portion of the tumor was removed by piecemeal. RESULTS: The tumor was totally removed in 29 patients and subtotally removed in 1 patient by second surgery. Follow-up showed that 27 patients resat normal life, 1 patient needed assistance, 1 died 7 days after surgery from inhalation asphyxia, and 1 died from complications of diabetes insipidus. CONCLUSIONS: Many different surgical approaches can be used in the treatment of carniopharyngioma according to the localization and extension of the tumor. However, avoidance of the neural structures injury in the third ventricle and preservation of the perforating arteries to hypothalamus are essential to achieving a good surgical result.

Adolescent↗
PubMed1999

[Expression and regulation of p16 in osteosarcoma].

OBJECTIVE: To study the expression and regulation of p16 and related factors in osteosarcoma. METHODS: The levels of p16 protein and related factors were explored by Western blot analysis in 12 cases of osteosarcoma tissues and in cells of different phases of osteosarcoma cell line OS732. The status of p16 protein in osteosarcoma cells was revealed by immunofluorescence analysis. RESULTS: p16 protein was detected in 10 of 12 osteosarcoma tissues. pRb was found in all of the specimens, but 8 of them were hyperphosphorylated. p16 protein was the least in G1 phase. Localized in cytoplasm during G1 phase, p16 protein gathered around nuclear envelope in S phase and entered the nucleus in G2 phase. CONCLUSIONS: The expression rate of p16 protein was 83.3% in osteosarcoma tissues. The expression of p16 protein was unable to inhibit the phosphorylation of pRb in most osteosarcomas; p16 protein was extremely low in G1 phase, presumably it was sufficient to inhibit the phosphorylation of pRb, causing abnormal proliferation of the cells.

Adolescent↗
PubMed1999

[Optical coherence tomography of macular holes].

OBJECTIVE: To study the characteristics and clinical application value of the optical coherence tomography (OCT) of macular holes. METHOD: A total of 35 patients with the clinical diagnosis of macular hole were examined with OCT between September and December 1998. OCT imaging was conducted through a dilated pupil, and the OCT images were analyzed and measured. RESULTS: Of the 35 patients examined with OCT, there were pseudohole and epimacular membrane in one eye, vitreofoveal traction in one eye, macular holes in 36 eyes, and 3 patients had macular hole in bilateral eyes. In 4 eyes, there were partial-thickness macular holes, and the defect of partial thickness of neural epithelium in the fovea without halo of retinal detachment was shown in the OCT image. In 32 eyes, there were full-thickness holes; the OCT displayed complete losing of the whole thickness of the neural epithelium in the fovea, sharp edge of the hole and the halo of retinal detachment around the hole. Sometimes nonreflective cavities could be seen within the retina, and the retinal thickness around the hole was increased. According to Gass stage classification of macular hole, there were 2 eyes with impending hole, 3 eyes in stage 2, 15 eyes in stage 3 and 6 eyes in stage 4. 4 eyes underwent vitrectomy. The OCT imaging after the surgery demonstrated the closure of hole and the disappearance of halo surrounding the hole. Through quantitative measurement, the diameter of the hole was (565.88 +/- 40.35) microm, the diameter of the halo was (1,338.76 +/- 147.57) microm, and the retinal thickness surrounding the hole was (391.87 +/- 18.97) microm. The sizes of the hole and the halo and the retinal thickness around the hole were correlated with the vision. CONCLUSION: OCT is a novel noninvasive, noncontact imaging technique. It is helpful in the diagnosis and differential diagnosis of the macular hole; the progress of the hole can be quantitatively estimated, and it is also helpful in selection of operation and assessment of operative therapeutic effects.

Adult↗
PubMed1999

[Effects and applications of ascorbic acid on the proliferation of Chlamydia trachomatis].

Two hundred and eighty-eight samples of patients with nongonococcal urethritis (NGU) and prostatitis were detected by cell culture and immunofluorescence assay for Chlamydia trachomatis (CT) and the effects of ascorbic acid(vitC) on the formation rate of inclusion of CT in positive samples were also studied. The results showed that the formation rate of inclusion of CT was 29.5% when the concentration of vitC was 5 micrograms.ml-1. The difference between test group and control group which contained cycloheximide in the media was insignificant (P > 0.05). The results suggested that vitC was a kind of nutrient needed for CT. The proliferation of CT in the cell can be promoted by vitC. We can replace cycloheximide by vitC in McCoy cell culture to detect clinic samples with CT.

Adult↗
PubMed1999

[Study on etiology of nongonococcal urethritis].

One thousand one hundred and fifty-seven samples from urogenital tract were detected by isolating culture and immunofluorescence. The positive rates of Chlamydia trachomatis (CT), Ureaplasma Urealyticum (UU), Mycoplasma hominis (Mh), Candida (Cd), Staphylococcus aureus were 27.8%, 33.5%, 25.6%, 11.5%, 23% respectively. The rate of mixed infection caused by at least two pathogens was 19.8%. About 90% of the infected patients were from 20 to 40 years old. The related factors of pathogen detection were also studied.

Adolescent↗
PubMed1999

[Experience of endoscopic sinus operation on 74 cases].

OBJECTIVE: To improve the curative effect of endoscopic sinus operation. METHOD: The clinical data of nasal cavity and nasal sinus via endoscopic sinus operation on 74 cases (115 sides) were in summary. Of those 74 cases, 65 were followed-up over six mothes. RESULT: It showed that 44 cases were cured, 18 were improved, 3 were ineffective. The effective rate was 95.4%. The disappearance rate of four symptons-nasal obstruction, headache, purulent nasal discharge and loss of smelling was 95.2%, 92%, 66.7% and 42.5%, respectively. The serious operative complication was absent. CONCLUSION: It helped to raise thd effect of anesthetization to apply nasal cavity surface anesthesia, nerve block anesthesia. Paying attention to the distinguish of dissection label can help to decrease the occurance of the serious complication of the sinus ethmoidal operation. The operation which was alternatively conducted between endoscope and cavascope, according to the operation requirement, can be carried out more thoroughly and more safely. Cleaning the operation cavity after operation can promote healing.

Adult↗
PubMed1999

[Determination of benzidine in cotton cloth by high performance liquid chromatography(HPLC)].

In this paper, a method for determination of benzidine in cotton cloth by HPLC was studied. First, cotton cloth was treated by sodium dithionite at the temperature of (70 +/- 2) degrees C. On this condition, azo dyes in cotton cloth were reduced to benzidine. Then benzidine was extracted by diethyl ether in sodium hydroxide solution. Benzidine originating from cotton cloth was analysed by HPLC with a column of Hypersil ODS (5 microns, 15 cm x 4.6 mm i.d.), mobile phase of V (MeOH):V(H2O) = 75:25, flow rate of 0.6 mL/min, pressure of 17.7 MPa and detection at 254 nm. By comparison with the standard sample, the retention time of benzidine was about 2.5 min. Benzidine in three samples was determined through parallel experiment. The mass ratio of benzidine in cotton cloth was 94.01, 86.9 and 120.8 micrograms/g, and the average was 100.57 micrograms/g. The average recovery was 84.7%. The experiment expressed that benzidine originating from cotton cloth could be qualitatively and quantitatively determined by HPLC. The accuracy of the results of parallel experiments was related to the reducing process. When the reducing conditions were completely consistent, the result would be more accurate.

English Abstract↗
PubMed1999

[Determination of monensin residue in chicken by HPLC with post-column derivatization].

The monensin residue was extracted from the tissue by homogenization with methanol-water and the extract was filtered and partitioned with dichloromethane. The dichloromethane extract is concentrated and clean up by passing through a silica gel cartridge. The analyte on the cartridge is then eluted with dichloromethane-methanol. The eluate is collected and evaporated to dryness. The residue is dissolved and made to a definite volume with 1 mL methanol and the solution is used for post-column derivatization-HPLC determination. Monensin is separated on mu-Bondapak C18 column (3.9 mm i.d. x 300 mm) with methanol-water-phosphoric acid as a mobile phase and the flow rate was 0.7 mL/min. The eluted monensin was reacted with vaniline under acidic and heated condition in post-column derivatization system then detected at 520 nm and quantitated by external standard method. The derivatization reagent consisted of 20 mL concentrated sulfuric acid, 950 mL methanol and 30 g vaniline. The flow rate was 0.7 mL/min. The reactor was a stainless steel coil (300 cm x 1 mm i.d.) set in a 90 degrees C oven. The response values was linear between 20-200 ng. The recovery was 88.1%-101.3%. The coefficient of variation was 0.1%-0.73%.

Animals↗