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Biomedical subjects

D Cheng

Publications and source records attributed to D Cheng.

At least 37 records · Page 2Linked to original sources
PubMed2001

Corrosion properties of nanocrystalline Co-Cr coatings.

Nanocrystalline and conventional Co-Cr (ASTM F75) coatings were prepared by plasma spraying for possible orthopedic implant applications. Scanning electron microscopy and transmission electron microscopy were used to study the macrostructure and microstructure of the resultant sprayed coatings. The corrosion resistance was characterized by an in vitro potentiodynamic anodic polarization technique in a pseudophysiological solution. The nanocrystalline coating has higher porosity, lower corrosion current density, and less localized damage than that of the conventional one, demonstrating better application potential for orthopedic implants. A change in the atomic compositional difference between the grain interior and the grain boundary, the presence of residual strain in the grain interiors, and a change in the repassivation kinetics are discussed as possible explanations for the enhanced corrosion behavior observed.

Alloys↗
PubMed2001

In situ activation of helper T cells in the lung.

To better understand the lung and systemic responses of helper T cells mediating memory immunity to Mycobacterium tuberculosis, we used three- and four-color flow cytometry to study the surface phenotype of CD4(+) lymphocytes. Bronchoalveolar lavage (BAL) fluid and peripheral blood (PB) samples were obtained from a total of 25 subjects, including 10 tuberculosis (TB)-infected subjects, 8 purified-protein-derivative-negative subjects, and 7 purified-protein-derivative-positive subjects. In marked contrast to CD4(+) lymphocytes from PB (9% +/- 5% expressing CD45RA and CD29), the majority (55% +/- 16%) of CD4(+) lymphocytes in BAL (ALs) simultaneously expressed CD45RA, a naïve T-cell marker, and CD29, members of the very late activation family. Further evaluation revealed that CD4(+) ALs expressed both CD45RA and CD45RO, a memory T-cell marker. In addition, the proportion of CD4(+) lymphocytes expressing CD69, an early activation marker, was drastically increased in BAL fluid (83% +/- 9%) compared to PB (1% +/- 1%), whereas no significant difference was seen in the expression of CD25, the low-affinity interleukin 2 receptor (34% +/- 15% versus 40% +/- 16%). More importantly, we identified a minor population of CD69(bright) CD25(bright) CD4(+) lymphocytes in BAL (10% +/- 6%) that were consistently absent from PB (1% +/- 1%). Thus, CD4(+) lymphocytes in the lung paradoxically coexpress surface molecules characteristic of naïve and memory helper T cells as well as surface molecules commonly associated with early and late stages of activation. No difference was observed for ALs obtained from TB-infected and uninfected lung segments in this regard. It remains to be determined if these surface molecules are induced by the alveolar environment or if CD4(+) lymphocytes coexpressing this unusual combination of surface molecules are selectively recruited from the circulation. Our data suggest that ex vivo experiments on helper T-cell subsets that display distinctive phenotypes may be pivotal to studies on the human immune response to potential TB vaccines.

Adult↗
PubMed2001

[The effects of intrapleural anti-TNFalpha antibody on chemical pleurodesis induced by talc slurry or doxycycline].

OBJECTIVE: To determine whether the intrapleural injection of TNFalpha neutralizing Fab antibody fragment (anti-TNFalpha Fab) would prevent the pleurodesis that occurs after the intrapleural injection of talc or doxycycline. METHODS: In a randomized blinded placebo controlled study, 34 New Zealand white rabbits were given 400 mg/kg talc or 10 mg/kg doxycycline intrapleurally as a sclerosant via a chest tube. Half of the rabbits in each group were also given polyclonal affinity purified anti-TNFalpha Fab 2 000 units or saline as placebo immediately before and 12 hours after the injection of the sclerosants. Chest tube were aspirated at 12 hours intervals until their removal at 4 days. Rabbits were sacrificed at 28 days. The pleural fluid volume, cell counts, LDH and pleurodesis scores were compared among groups. RESULTS: Both talc and doxycycline produced an exudative pleural effusion. The pleural fluid volume and LDH levels were significantly greater in the doxycycline group than talc group. However, the pleural fluid leukocyte counts in talc group were higher than doxycycline group. The administration of anti-TNFalpha Fab had no significant effect on pleural fluid volume, LDH or leukocyte counts in either groups. However, the intrapleural administration of anti-TNFalpha Fab results in a significant decrease in the pleurodesis score for the talc group than doxycycline group (1.8 +/- 0.9 vs 3.2 +/- 0.8). In contrast the pleurodesis score was virtually identical in the doxycycline group with (3.5 +/- 0.5) and without (3.4 +/- 0.7) anti-TNFalpha Fab. CONCLUSION: The intrapleural administration of anti-TNFalpha Fab diminishes the pleurodesis induced by talc but not that which results from doxycycline. These findings suggest that different mechanisms are involed with the two different sclerosants.

Animals↗
PubMed2001

[Cardio-pulmonary pathology of sudden death in asthma].

OBJECTIVE: To elucidate the pathological characteristics of the heart and lung in asthmatics with sudden death. METHOD: A detail analysis of pathological data was performed on 14 patients with sudden death in asthma. RESULTS: There was no apparent gender difference among 14 patients. 9 patients were younger than 30 years old. Pathological examination showed that bronchial infiltration of eosinophils in 14 patient (100%), thickened basement membrane of the bronchial mucosa in 12 patients (85.7%), proliferation of smooth muscle cells in 11 patients (78.6%), proliferative mucous gland in 9 patients (64.3%), mucous plug in bronchiole in 8 patients (57.1%), and cicatvization of left ventricle in 10 patients (71.4%). CONCLUSION: Severe nonspecific airway inflammation is demonstrated in asthmatic patients with sudden death. Lesions of the left ventricle and mucous plug in bronchiole may contribute to the main cause leading sudden death.

Adolescent↗
PubMed2001

[The expression of tyrosine-kinase receptor flk-1 and hypoxic pulmonary vascular remodeling in the lung of rats exposed to hypoxia].

OBJECTIVE: To assess the role of tyrosine-kinase receptor flk-1 in the development of hypoxic pulmonary vascular remodeling. METHODS: We divided 20 male Wistar rats into two groups(control vs hypoxia) and exposed them to normoxic condition and isobaric hypoxia for 3 weeks respectively. The pulmonary artery pressure was measured by right cardiac catheterization. The expression of flk-1 in lung tissues was measured by immunohistochemical staining. Histologic sections of the lungs were examined by a computerized image analyser. RESULTS: In hypoxic rats, the pulmonary artery pressure was significantly raised to a higher level, P < 0.01; the cell number of vascular wall was significantly increased. The results also demonstrated that chronic hypoxia brought about the significant increment in thickness of wall with narrowing of lumen of pulmonary arterioles, and the increment in the percent of vascular wall thickness/vascular external diameter (WT%) and the percent of vascular wall area/total vascular area (WA%), P < 0.01. The positive staining of flk-1 in the wall of pulmonary arteriole of rats treated with hypoxia was significantly stronger than that of normal rats, P < 0.01. Positive correlations were seen between the increment of expression of flk-1 with WT% and WA% (r = 0.714, 0.738, P < 0.01). CONCLUSION: Chronic hypoxia can induce an increasing expression of flk-1, and the flk-1 may play an important role in the pathogenesis of hypoxic pulmonary vascular remodeling.

Animals↗
PubMed2000

Treatment of severe systemic lupus erythematosus with high-dose chemotherapy and haemopoietic stem-cell transplantation: a phase I study.

BACKGROUND: Patients with systemic lupus erythematosus (SLE) who experience persistent multiorgan dysfunction, despite standard doses of intravenous cyclophosphamide, represent a subset of patients at high risk of early death. We investigated the safety and efficacy of immune suppression and autologous haemopoietic stem-cell infusion to treat such patients. METHODS: From 1996, we selected patients with persistent SLE despite use of cyclophosphamide. Patients underwent dose-intense immune suppression and autologous haemopoietic stem-cell (CD34) infusion. Peripheral blood lymphocytes were analysed by flow cytometry, ELISA, and T-cell-receptor spectratyping before and after transplantation. We mobilised autologous haemopoietic stem cells with 2.0 g/m2 cyclophosphamide and 10 microg/kg granulocyte colony stimulating factor daily, enriched with CD34-positive selection, and reinfused after immunosuppression with 200 mg/kg cyclophosphamide, 1 g methylprednisolone, and 90 mg/kg equine antithymocyte globulin. RESULTS: Nine patients underwent stem-cell mobilisation but two were excluded before transplantation because of infection. The remaining seven received high-dose chemotherapy and stem-cell infusion. Median time to an absolute neutrophil count higher than 0.5x10(9)/L and nontransfused platelet count higher than 20x10(9)/L was 9 days (range 8-11) and 11 days (10-13), respectively. At a median follow-up of 25 months (12-40), all patients were free from signs of active lupus. Renal, cardiac, pulmonary, and serological markers, and T cell phenotype and repertoire had normalised. INTERPRETATION: Patients remained free from active lupus and improved continuously after transplantation, with no immunosuppressive medication or small residual doses of prednisone. T-cell repertoire diversity and responsiveness was restored. Durability of remission remains to be established.

Adolescent↗
PubMed2000

A controlled study of imagery rehearsal for chronic nightmares in sexual assault survivors with PTSD: a preliminary report.

Imagery-rehearsal therapy for chronic nightmares was assessed in a randomized, controlled study of sexual assault survivors with posttraumatic stress disorder (PTSD). Nightmares, sleep quality, and PTSD were assessed at baseline for 169 women, who were randomized into two groups: treatment (n = 87) and wait-list control (n = 82). Treatment consisted of two 3-hr sessions and one 1-hr session conducted over 5 weeks. Of 169 participants, 91 women (Treatment, n = 43, Control, n = 48) completed a 3-month follow-up and 78 did not. At follow-up, nightmare frequency and PTSD severity decreased and sleep quality improved in the treatment group with small to minimal changes in the control group. Treatment effects were moderate to high (Cohen's d ranged from 0.57 to 1.26). Notwithstanding the large dropout rate, imagery-rehearsal therapy is an effective treatment for chronic nightmares in sexual assault survivors with PTSD and is associated with improvement in sleep quality and decreases in PTSD severity.

Adult↗
PubMed2000

Vascular endothelial growth factor level correlates with transforming growth factor-beta isoform levels in pleural effusions.

BACKGROUND: Recent studies have demonstrated high levels of vascular endothelial growth factor (VEGF) in exudative pleural effusions and a possible etiologic role. The factors regulating VEGF accumulation in the pleural space are unknown. Transforming growth factor (TGF)-beta is a potent stimulator of VEGF expression in vitro. We hypothesized that TGF-beta induces VEGF production in pleural tissues, and, hence, the pleural fluid VEGF levels should correlate with the levels of TGF-beta in pleural fluid of different etiologies. METHODS: Seventy pleural fluid samples were analyzed. These included 20 malignant, 13 post-coronary artery bypass grafting (CABG), 8 parapneumonic, 11 miscellaneous exudative, and 18 congestive heart failure (CHF) pleural effusions. RESULTS: Pleural fluid VEGF levels showed good correlation with those of TGF-beta(1) (r = 0.58; p < 0. 0001), TGF-beta(2) (r = 0.43; p < 0.001), and lactate dehydrogenase (r = 0.65; p < 0.001). The levels of TGF-beta(1) and TGF-beta(2) also were correlated (r = 0.60; p < 0.0001). The median levels of TGF-beta(1) (2,480 pg/mL) and TGF-beta(2) (266 pg/mL) in the CHF group were significantly lower than those in the malignant (TGF-beta(1), 4,902 pg/mL; TGF-beta(2), 428 pg/mL), post-CABG (TGF-beta(1), 5,456 pg/mL; TGF-beta(2), 377 pg/mL), parapneumonic (TGF-beta(1), 5,024 pg/mL; TGF-beta(2), 464 pg/mL), and miscellaneous exudate groups (TGF-beta(1), 7,690 pg/mL; TGF-beta(2), 369 pg/mL). There was no significant difference in TGF-beta(1) and TGF-beta(2) levels among the four exudate groups. CONCLUSIONS: VEGF levels in pleural effusions are significantly correlated with the levels of TGF-beta(1) and beta(2) isoforms. VEGF, TGF-beta(1), and TGF-beta(2) levels were all higher in exudative effusions than in effusions secondary to CHF.

Endothelial Growth Factors↗
PubMed2000

Loss of imprinting of the IGF-II and H19 genes in epithelial ovarian cancer.

To establish a possible role of genomic imprinting in the carcinogenesis of epithelial ovarian cancer, we determined the imprinting status of both IGF-II and H19 genes in 43 ovarian cancers, 7 low malignant potential ovarian tumors, and their matched normal tissues. In ovarian cancer, loss of heterozygosity (LOH) of IGF-II, H19 RsaI, and H19 AluI was found in 4 of 24 (16.7%), 3 of 20 (15%), and 1 of 16 (6.3%) samples, respectively. All patients with tumor specimens exhibiting LOH are of advanced clinical stages. Loss of imprinting (LOI) was found in 5 of 20 (25%) for IGF-II and in 4 of 17 (23.5%) and 1 of 15 (6.7%) for the RsaI and AluI sites of H19 gene with no LOH. However, no LOH was found in low malignant potential tumors, and only one of them showed LOI in H19 AluI site. Overexpression of IGF-II was demonstrated in all five LOI samples with normal expression of H19. Three of the five tumor specimens exhibiting LOI were transcribed from P1 promoter, whereas the remaining two were from the P3 promoter. These results suggested that LOH of both IGF-II and H19 genes was associated with advanced ovarian cancer. LOI of IGF-II and H19 genes may be involved in the development of ovarian cancer. Transcription of IGF-II from the P1 promoter may account for the biallelic expression of the IGF-II gene.

Female↗
PubMed2000

[Study on genetic mutations of the vWF in type 2A von Willebrand disease].

OBJECTIVE: To study the molecular pathological mechanism of the type 2A von Willebrand disease(vWD) and the relationship of the phenotypes with genotypes. METHODS: A total of 126 patients with the hereditary hemorrhagic disease were examined using bleeding time, vWF:Ag, FVIII:CAg, ristocentin induced platelet agglutination assay(RIPA) and multimer analysis of plasma. The exon 28 of authenticity vWF gene was studied by PCR, denaturing gradient gel electrophoresis(DGGE) and sequencing in the type 2A vWD. RESULTS: Fourteen cases were diagnosed as type 2A vWD. Four cases of point mutations resulting in single animo acid substitutions, Arg611His, Ala737Glu, Arg834Trp, were identified in 3 families of type 2A vWD. Ala737Glu substitution in vWF is caused by a novel missense mutation. CONCLUSION: The molecular pathological mechanism of the type 2A vWD is very variant.

Adolescent↗
PubMed2000

The calibration of a 2.5x Galilean focusable telescope as an optometer for refraction.

A 2.5x Selsi achromatic Galilean focusable telescope was calibrated for refraction at 6 m. In its calibration, minus power trial lens was placed at the objective of the telescope to simulate vergence of a target at a finite distance, before the back vertex power (BVP) of the telescope at each setting (telescope length) was measured by a focimeter. By using a graphical presentation of the results, the BVP of the telescope at each setting could be determined at different selected target distances. For a target vergence of -0.167 D or a distance of 6 m, the common testing distance in clinical practice, this calibrated telescope had a BVP or refraction measuring range of -7.27(-)+7.52 D. When this telescope was used to measure simulated manifest refractive errors at 6 m, it yielded a mean error of +0.13 D with a 95% confidence limit of agreement of -0.38(-)+0.64 D. These results indicated that the accuracy and precision of telescopic refraction were comparable to that of retinoscopy. Therefore, the calibrated telescope could be considered as a reliable and inexpensive instrument for determining spherical refractive errors. Telescopic refraction is applicable in refracting economically disadvantaged population in underserved areas where modern equipment and electricity are not available. In addition, it provides an alternative subjective refraction method for low vision population because the magnification of this calibrated telescope has the advantage of allowing low vision patients to be refracted at the common 6 m testing distance in clinical practice.

Adult↗
PubMed2000

The intrauterine device: still misunderstood after all these years.

The intrauterine device (IUD) is one of the most effective, safe, and economic methods of contraception today. It is used by more women worldwide than any other reversible method of birth control, yet less than 1% of women in the United States use the IUD. Still remembering the tragedy of the notorious Dalkon Shield, American pharmaceutical companies and clinicians have been wary about promoting any IUD, leaving most physicians inadequately trained in the two IUDs available in the United States. Most significantly, misconceptions about the IUD's safety, mechanism of action, complication rates, and liability have severely limited the utilization of the IUD by many practitioners and women in the United States who may greatly benefit from it.

Adolescent↗
PubMed2000

P73 gene expression in ovarian cancer tissues and cell lines.

Thep73 gene, a homology of p53, is a new candidate of imprinting and tumor suppressor gene. To investigate the role of p73 in ovarian cancer, we studied the allelic expression in 56 cases of ovarian cancer using StyI polymorphism analysis. We also examined p73 expression by semi-quantitative reverse transcription-PCR as well as by Western blot analysis and DNA methylation study of the CpG island in exon 1 in ovarian cancer tissues and cell lines. Loss of heterozygosity was found in 8.3% (2 of 24) of the cases. Biallelic expression was demonstrated in 91.7% (22 of 24) of the tumor samples, in 70.8% (17 of 24) of the normal samples, and in 1 ovarian cancer cell line. Imbalanced expression and monoallelic expression were found in three and two pairs of matched samples, respectively. Overexpression of p73 was found in advanced ovarian cancer rather than in early-stage disease or in borderline ovarian tumor. No significant difference was found in the p53 expression. Three cell lines with absent p73 protein expression and one tumor sample with monoallelic expression were methylated in the CpG island. Demethylation in SKOV3 cell line using 5-azacytidine can reactivate the expression of this gene in both the mRNA and the protein level. Our results indicated that p73 was not imprinted in most of the ovarian cancer and normal tissues, but it could be involved in the advanced ovarian cancer through overexpression. DNA methylation may contribute to the lack of p73 expression.

Adenocarcinoma, Clear Cell↗
PubMed2000

[The acute effect of tetrandrine pulmonary targeting microspheres on hypoxic pulmonary hypertension in rats].

OBJECTIVE: To investigate the effect of tetrandrine (Tet) pulmonary targeting microspheres on hypoxic pulmonary hypertension and its selective role on pulmonary circulation. METHODS: Tet pulmonary targeting microspheres were synthesized by spraying desiccation, the content of tetrandrine in pulmonary targeting microspheres is 32%. Twenty Wistar rats were exposed to hypoxia for three weeks, the rats were given Tet pulmonary targeting microspheres and Tet aqueous solution respectively and another 10 rats were as normal control. The mean pulmonary arterial pressure (mPAP) was measured by a right cardiac catheterization, mean systemic blood pressure (mSBP) was measured by left femoral catheterization. RESULTS: At the end of hypoxic treatment, rats developed pulmonary hypertension. mPAP in the rats receiving Tet pulmonary targeting microspheres decreased more obviously than the rats receiving Tet aqueous solution (P < 0.05), and the effects maintained for 60 min after administration. However, the mSBP remained normal in rats receiving Tet pulmonary targeting microspheres. CONCLUSION: Tet pulmonary targeting microspheres can improve the effect of Tet on the hypoxic pulmonary hypertension and Tet has the selective role on the pulmonary circulation.

Alkaloids↗
PubMed2000

[Changes of type I collagen in the lungs of rats with hypoxic pulmonary hypertension].

The changes of type I collagen in the lung tissues of rats with hypoxic pulmonary hypertension (HPH) and its relationship to the mean pulmonary arterial pressure (mPAP) were investigated. The blood dynamic indexes of pulmonary circulation were measured by using Swan-Ganz. The distribution of type I collagen in pulmonary arteries, bronchi and plumonary interstitial was observed by using streptavidin peroxidase method (SP). The morphologic changes of small pulmonary arteries and the level of type I collagen were determined by image pattern analysis technique and gray scale scanning, respectively. The results showed, compared with the controls, mPAP of the hypoxic rats elevated (from 2.12 +/- 0.25 to 3.95 +/- 0.43 kPa, P < 0.01), their small pulmonary arteries, walls thickened (MT% from 16.35 +/- 2.64 to 35.83 +/- 3.55, MA% from 26.83 +/- 3.40 to 59.68 +/- 4.90, P < 0.01) and lumen narrowed. The distribution of type I collagen was mainly in the external layer of pulmonary arterial walls; the positive degrees of gray scale scanning increased and had a positive linear relationship to the mPAP and MT%. These findings suggest that the increase of type I collagen contents in pulmonary arteries is closely related to the development of HPH.

Animals↗