Biomedical subjects

D Yu

Publications and source records attributed to D Yu.

At least 91 records · Page 5Linked to original sources

PubMed2000

Human immunodeficiency virus Env-independent infection of human CD4(-) cells.

CD4(-) epithelial cells covering mucosal surfaces serve as the primary barrier to prevent human immunodeficiency virus type 1 (HIV-1) infection. We used HIV-1 vectors carrying the enhanced green fluorescent protein gene as a reporter gene to demonstrate that HIV-1 can infect some CD4(-) human epithelial cell lines with low but significant efficiencies. Importantly, HIV-1 infection of these cell lines is independent of HIV-1 envelope proteins. The Env-independent infection of CD4(-) cells by HIV-1 suggests an alternative pathway for HIV-1 transmission. Even on virions bearing Env, a neutralizing antibody directed against gp120 is incapable of neutralizing the infection of these cells, thus raising potential implications for HIV-1 vaccine development.

CD4 Antigens↗

PubMed2000

E1A-mediated paclitaxel sensitization in HER-2/neu-overexpressing ovarian cancer SKOV3.ip1 through apoptosis involving the caspase-3 pathway.

HER-2/neu-overexpressing breast cancer cells are more resistant to the chemotherapeutic agent paclitaxel (Taxol) than low-HER-2/neu-expressing breast cancer cells, and the adenoviral type 5 EIA can down-regulate HER-2/neu overexpression. Therefore, in this study, we asked (a) whether EIA might sensitize response to paclitaxel in human HER-2/neu-overexpressing ovarian cancer cells, and, if so, what is the mechanism responsible; and (b) whether this enhanced chemosensitivity would translate into a therapeutic effect in an ovarian cancer xenograft model. Consequently, we demonstrated that: (a) adenovirus type 5 E1A could enhance the sensitivity of paclitaxel in paclitaxel-resistant HER-2/neu-overexpressing human ovarian cancer cells in vitro by inducing apoptosis, (b) this induction was heavily dependent on activation of the caspase-3 pathway, and (c) nude mice bearing i.p. HER-2/neu-overexpressing human ovarian cancer cells and treated with both paclitaxel and E1A gene therapy survived significantly longer than did mice treated only with paclitaxel or E1A gene therapy. Thus, we concluded that the E1A gene enhanced both the in vitro and in vivo sensitivity of paclitaxel in paclitaxel-resistant HER-2/ neu-overexpressing ovarian cancer SKOV3.ipl cells. Because a Phase I clinical trial using E1A gene targeted to HER-2/neu down-regulation has recently been completed, the current study also provided a scientific basis to further develop a novel therapy that combines paclitaxel and E1A gene therapy and its testing in a Phase II trial.

Adenovirus E1A Proteins↗

PubMed2000

The evidence regarding the drugs used for ventricular rate control.

OBJECTIVE: Our goal was to determine what drugs are most efficacious for controlling the ventricular rate in patients with atrial fibrillation. SEARCH STRATEGY: We conducted a systematic review of the literature published before May 1998, beginning with searches of The Cochrane Collaboration's CENTRAL database and MEDLINE. SELECTION CRITERIA: We included English-language articles describing randomized controlled trials of drugs used for heart rate control in adults with atrial fibrillation. DATA COLLECTION/ANALYSIS: Abstracts of trials were reviewed independently by 2 members of the study team. We reviewed English-language abstracts of non-English-language publications to assess qualitative consistency with our results. MAIN RESULTS: Forty-five articles evaluating 17 drugs met our criteria for review. In the 5 trials of verapamil and 5 of diltiazem, heart rate was reduced significantly (P <.05), both at rest and with exercise, compared with placebo, with equivalent or improved exercise tolerance in 6 of 7 comparisons. In 7 of 12 comparisons of a beta-blocker with placebo, the beta-blocker was efficacious for control of resting heart rate, with evidence that the effect is drug specific, as nadolol and atenolol proved to be most efficacious. All 9 comparisons demonstrated good heart rate control with beta-blockers during exercise, although exercise tolerance was compromised in 3 of 9 comparisons. In 7 of 8 trials, digoxin administered alone slowed the resting heart rate more than placebo, but it did not significantly slow the rate during exercise in 4 studies. The trials evaluating other drugs yielded insufficient evidence to support their use, but those drugs may yet be promising. CONCLUSIONS: The calcium-channel blockers verapamil or diltiazem, or select beta-blockers are efficacious for heart rate control at rest and during exercise for patients with atrial fibrillation without a clinically important decrease in exercise tolerance. Digoxin is useful when rate control during exercise is less a concern.

Adrenergic beta-Antagonists↗

PubMed2000

An in vivo function for the transforming Myc protein: elicitation of the angiogenic phenotype.

The ability of neoplastic cells to recruit blood vasculature is crucial to their survival in the host organism. However, the evidence linking dominant oncogenes to the angiogenic switch remains incomplete. We demonstrate here that Myc, an oncoprotein implicated in many human malignancies, stimulates neovascularization. As an experimental model, we used Rat-1A fibroblasts that form vascular tumors upon transformation by Myc in immunocompromised mice. Our previous work and the use of neutralizing antibodies reveal that in these cells, the angiogenic switch is achieved via down-modulation of thrombospondin-1, a secreted inhibitor of angiogenesis, whereas the levels of vascular endothelial growth factor, a major activator of angiogenesis, remain high and unaffected by Myc. Consistent with this finding, overexpression of Myc confers upon the conditioned media the ability to promote migration of adjacent endothelial cells in vitro and corneal neovascularization in vivo. Furthermore, mobilization of estrogen-dependent Myc in vivo with the appropriate steroid provokes neovascularization of cell implants embedded in Matrigel. These data suggest that Myc is fully competent to trigger the angiogenic switch in vivo and that secondary events may not be required for neovascularization of Myc-induced tumors.

Animals↗

PubMed2000

[The cloning and expression of soluble HLA-B27 gene].

OBJECTIVE: To clone and express the soluble HLA-B27 (sB27) gene in human B lymphoid cell line. METHODS: Soluble B27 cDNA was constructed by 3 consecutive rounds of PCR and then cloned into the RSV5neo vector. The construct was transfected into C1R cells. RESULTS: Restriction enzyme digestion and DNA sequencing confirmed that the construct was the HLA-B27 gene lacking exon 5 which encodes the transmembrane domain of HLA molecule. The expression of aHLA-B27 was verified successfully in the culture supernatant of C1R cells. The level of sHLA-B27 changed with variable culture conditions, such as temperature and concentration of fetal calf serum. CONCLUSION: The sHLA-B27 molecules can be generated by alternative splicing of HLA-B27 pre-mRNA. Our construct provide a useful model for studying the effect of environmental factors such as bacterial infections and cytokine stimulation on the expression of soluble HLA-B27 molecule. It will also provide clues for the role of HLA-B27 molecule in the pathogenesis of spondyloarthropathies.

Cell Line↗

PubMed2000

Potent induction of apoptosis by beta-lapachone in human multiple myeloma cell lines and patient cells.

BACKGROUND: Human multiple myeloma (MM) remains an incurable hematological malignancy. We have reported that beta-lapachone, a pure compound derived from a plant, can induce cell death in a variety of human carcinoma cells, including ovary, colon, lung, prostate, pancreas, and breast, suggesting a wide spectrum of anticancer activity. MATERIALS AND METHODS: We first studied antisurvival effects of beta-lapachone in human MM cells by colony formation assay. To determine whether the differential inhibition of colony formation occurs through antiproliferative activity, we performed MTT assays. The cytotoxicity of beta-lapachone on human peripheral blood mononuclear cells was also measured by MTT assay. To determine whether the cell death induced by beta-lapachone occurs through necrosis or apoptosis, we used the propidium iodide staining procedure to determine the sub-GI fraction, Annexin-V staining for externalization of phosphatidylserine, and fragmentation of cellular genomic DNA subjected to gel electrophoresis. To investigate the mechanism of anti-MM activity, we examined Bcl-2 expression, cytochrome C release, and poly (ADP ribose) polymerase cleavage by Western blot assay. RESULTS: We found that beta-lapachone (less than 4 microM) inhibits cell survival and proliferation by triggering cell death with characteristics of apoptosis in ARH-77, HS Sultan, and MM.1S cell lines, in freshly derived patient MM cells (MM.As), MM cell lines resistant to dexamethasone (MM.1R), doxorubicin (DOX.40), mitoxantrone (MR.20), and mephalan (LR5). Importantly, after treatment with beta-lapachone, we observed no apoptosis in peripheral blood mononuclear cells in either quiescent or proliferative states, freshly isolated from healthy donors. In beta-lapachone treated ARH-77, cytochrome C was released from mitochondria to cytosol, and poly (ADP ribose) polymerase was cleaved, signature events of apoptosis. Finally, the apoptosis induced by beta-lapachone in MM cells was not blocked by either interleukin-6 or Bcl-2, which confer multidrug resistance in MM. CONCLUSIONS: Our results suggest potential therapeutic application of beta-lapachone against MM, particularly to overcome drug resistance in relapsed patients.

Antibiotics, Antineoplastic↗

PubMed2000

Anticalculus effect of two zinc citrate/essential oil-containing dentifrices.

PURPOSE: To assess the feasibility of incorporating zinc citrate, a known anticalculus ingredient, into a dentifrice formulation containing a fixed combination of essential oils, a known antiplaque/antigingivitis agent. MATERIALS AND METHODS: This randomized, parallel, double-blind study evaluated the potential of two essential oil dentifrice formulations containing different levels of zinc citrate (1.0% and 2.0% ZCT) to reduce supragingival calculus formation compared to a marketed control dentifrice, Crest Regular. Following a 3-month pre-test phase, subjects received a dental prophylaxis, were stratified into three balanced groups on the basis of Volpe-Manhold calculus scores and brushed twice daily with their assigned dentifrice for 3 months. RESULTS: One hundred ninety-six evaluable subjects completed all phases of the study. ANCOVA revealed that the 1.0% ZCT and 2.0% ZCT essential oil dentifrice formulations provided significant reductions in calculus formation of 26.4% and 29.0% (P< 0.001), respectively, compared to the control dentifrice, Crest Regular. The magnitude of calculus reductions is similar to those levels obtained by other zinc salt formulations.

Adolescent↗

PubMed2000

Caries inhibition efficacy of an antiplaque/antigingivitis dentifrice.

PURPOSE: To evaluate the efficacy of a fluoride dentifrice containing a fixed combination of essential oils (Thymol, Menthol, Eucalyptol, and Methyl Salicylate) in preventing caries in Sprague Dawley rats. MATERIALS AND METHODS: The dentifrice contains 0.76% sodium monofluorophosphate (SMFP) as the fluoride source and a silica abrasive system. A fluoride-free placebo and a clinically proven USP dentifrice reference standard for SMFP/silica were included as controls. Three groups of 45 SDV-free Sprague Dawley weanlings were infected by a cariogenic strain of Streptococcus sobrinus and fed cariogenic diet NIH 2000 ad libitum. Animals were treated twice daily (once on weekends) with the assigned dentifrice using a cotton-tipped applicator, for 5 wks, after which they were terminated and caries scored using Larson's modification of the Keyes method. RESULTS: Analyses of variance were used to compare inter-group means, the total E lesion score was the primary efficacy variable. Compared with the fluoride-free vehicle control, the experimental dentifrice and USP reference standard dentifrice produced a statistically significant reductions of 18.3% and 12.2% respectively for total caries score (P<0.001). Compared with the clinically tested USP positive control dentifrice, the experimental dentifrice produced a statistically significant reduction in the total caries score of 6.9% (P=0.028). The results of this study show that 1) both the new dentifrice containing essential oils and USP dentifrice are statistically significantly effective in reducing caries in the rat model, 2) the anticaries activity of the SMFP dentifrice is not adversely affected with the addition of essential oils.

Analysis of Variance↗

PubMed2000

Stain removal efficacy of two new fluoride dentifrices containing essential oils.

PURPOSE: To assess in vitro the stain removal efficacy of two new antiplaque/antigingivitis dentifrices utilizing a modification of a previously validated Stookey method. MATERIALS AND METHODS: The modifications to the original Stookey method are the following: (1) study design; three 5 x 5 Latin Squares were employed to minimize bias stemming from position or test run in the study. (2) statistical success criteria; a test formulation was judged to be effective if the lower one-sided 95% confidence limit was "equal to or higher than" 50 since a minimum PCR (pellicle cleaning ratio) score of 50 is needed for a dentifrice to show clinical efficacy. The two test dentifrice formulations contained a fluoride source, a silica abrasive system, and four essential oils. The ADA reference abrasive material (calcium pyrophosphate) and placebo toothpaste were included as positive and negative controls, respectively. RESULTS: Compared to the negative control, the positive control exhibited a statistically higher PCR score; therefore, the validity of this modified Stookey method was confirmed. Additionally, the lower limits of the one-sided 95% confidence interval for the two dentifrice formulations were above the threshold PCR of 50; therefore, this modified Stookey method should predict that both essential oil-containing dentifrices possess acceptable stain removal power.

Analysis of Variance↗

PubMed2000

P16 overexpression in pituitary adenomas studied by immunohistochemistry and in situ hybridization.

OBJECTIVES: To examine the expression of p16 gene and the clinicopathological characteristics of 31 pituitary adenomas. To investigate the relationship between p16 expression and cell proliferative activity by analyzing the expression of proliferating cell nuclear antigens (PCNA). METHODS: Immunohistochemistry and in situ hybridization were performed on freshly-prepared paraffin-embedded specimens of 31 pituitary adenomas. RESULTS: Varying degrees of overexpression of the p16 gene was found in the tumors specimens. A higher proportion of p16 positive tumor cells was associated with bigger size, more frequent invasion and higher recurrence of the tumors. The expression of p16 was found to be significantly associated with the degree of PCNA expression. CONCLUSION: Though inactivation of the p16 gene is known in wide range of tumors, our study suggested that p16 overexpression might play a role in the development and progression of pituitary adenomas.

Adenoma↗

PubMed2000

[Study on the application of random amplified polymorphic DNA in Yersinia pestis genotyping].

OBJECTIVE: To study the type of 103 Y. pestis strains that isolated from different plague foci and different ecological types. METHOD: Random amplified polymorphic DNA (RAPD) was used. RESULTS: Y. pestis were divided into two RAPD types: most strains that isolated from elsewhere in the country belonged to RAPD-1 type, while most strains that isolated from Qinghai province were RAPD-2 type. CONCLUSION: The genome structures of different ecotype Y. pestis were different providing the foundation of further research and prevention of plague.

Animals↗

PubMed2000

[Drinking water types, microcystins and colorectal cancer].

OBJECTIVE: To assess the relationship between microcystins (a blue-green algal toxin) in drinking water and colorectal cancer. METHODS: Eight townships were randomly selected as study sites in Haining city of Zhejiang province, China. Four hundred and eight colon and rectum carcinoma cases diagnosed from 1977 to 1996 were identified from cancer registry in the study sites. A retrospective survey on types of drinking water of all 408 cases was conducted. Population data and drinking water sources data were provided by local household registration and local health institution, respectively. Water samples from different sources (well, tap-water, river and pond) were collected and microcystins concentrations were measured by an indirect competitive ELISA method. RESULTS: The incidence rates of colorectal cancer were significantly higher among people drinking river or pond water than those who drank well water or tap-water in both males and females. And comparing with other sources to well water, the relative risks (RR) were much higher for people using river water (7.94) and pond water (7.70). The positive detection rates (> 50 pg/ml) of microcystin in well, tap-water, river and pond water were 0.00%, 0.00%, 36.23% and 17.14% respectively. The highest concentrations of microcystins were 1 083.43 pg/ml (river) and 1 937.94 pg/ml (pond) in the positive samples. Microcystins concentrations in river and pond were significantly higher than the concentrations in well and tap water (P < 0.01). The Spearman rank correlation analysis showed that in the study sites, the microcystins concentrations of river and pond water were positively correlated with the incidence of colorectal cancer (r = 0.881, P < 0.01). CONCLUSION: Drinking surface water (river or pond) is one of the risk factors for colorectal cancer. Microcystins may be associated with incidence of colorectal cancer. It is suggested that further study should be carried out to clarify the relationship between colorectal cancer and microcystin in drinking water.

Bacterial Toxins↗

PubMed2000

[Effects of fluoride on the expression of c-fos and c-jun genes and cell proliferation of rat osteoblasts].

OBJECTIVE: To investigate the effects of sodium fluoride (NaF) on the expression of c-Fos and c-Jun genes and osteoblast cell proliferation of rat osteoblasts. METHODS: Osteoblastic cells were isolated from baby rat calvaria, and cultured in the presence of different doses of NaF (10(-5) mol/L, 10(-4) mol/L, and 10(-3) mol/L). Cell proliferation was measured by the MTT method, and c-Fos and c-Jun expression was detected by the immunohistochemistry combined with image analysis compute system. RESULTS RESULTS: from the MTT assay showed that NaF increased the proliferation of rat osteoblast and induced the expression of c-Fos and c-Jun genes. The increases of c-Fos and c-Jun expression by the 3 different doses of NaF were 5.4%, 15.4% and 42.3% for the c-Fos gene and 12.1%, 14.4% and 38.6% for c-Jun gene respectively (P < 0.05 and P < 0.01). CONCLUSION: NaF increased rat osteoblastic cell proliferation and the expression of genes involved in cell proliferation.

Animals↗

PubMed2000

[The outcome of 1268 cases of endoscopic sinus surgery].

OBJECTIVE: To evaluate the curative effect of endoscopic sinus surgery (ESS). METHODS: One thousand two hundred and sixty-eight cases with chronic sinusitis and nasal polyps undergone ESS from 1989 to 1997 were appraised with the standard criteria (Chinese ENT Association, 1997). There were 366 cases(28.9%) in type 1, 646 cases(50.9%) in type 2 and 256 cases(20.2%) in type 3. One thousand two hundred and sixty-two cases underwent ESS under intranasal local anesthesia and sedation; 182 cases underwent submucous resection of nasal septum or septoplasty. Long-term follow-up was performed at 9 to 42 months(mean = 15 months). RESULTS: The results showed that cure rate was 93.7% for type 1, 81.6% for type 2 and 68.4% for type 3. There was significant difference in cure rate among different types (P < 0.01). Complication of ESS in 1,268 cases occurred in 2.3%. CONCLUSION: ESS is efficacy and safe in the treatment of nasal polyps and chronic sinusitis. The cure result is directly related to the types of the disease.

Adult↗

PubMed2000

[T-lymphocyte subsets and inflammatory cytokines of interleukin-5 and interleukin-10 expression in human nasal polyp tissue].

OBJECTIVE: To investigate the distribution of T-lymphocyte subsets (CD4+ and CD8+ cells) and the expression of IL-5 and IL-10 protein-positive cells in nasal polyps. METHODS: The specimens of thirty-two nasal polyps and six control subjects were studied by Immunohistochemical method to detect CD4+, CD8+, IL-5+ and IL-10+ cells. A mean numbers of positive cells per high power field (10 x 40) were counted. All data were analyzed with t-test and correl-test. RESULTS: There were significantly large number of CD4+ and CD8+ cells in nasal polyps (P < 0.001). A significant predominance of CD4+ cells over CD8+ cells was found in the two subgroups (subepithelia, arounding glands and blood vessels) of nasal polyp (P < 0.001). There were an abundant number of IL-5+ IL-10+ cells, whereas significantly difference higher concentrations than that in the controls (P < 0.001). IL-5+ cells were more than IL-10+ cells in nasal polyps (P < 0.05), and most of IL-5+ cells were plasmacytes and lymphocytes. There was a significant correlation between the counts of CD4+/CD8+ and IL-5+/IL-10+ in the subgroup of nasal polyps arounding glands and blood vessels (r = 0.78, P < 0.01). CONCLUSIONS: This study indicated that CD4+ T-lymphocytes and IL-5 high expression may play an important role in the nasal polyps. Migration of plasmacytes and lymphocytes in polyps may participate in the inflammatory reaction. The disturbance of cellular and humoral immunity and imbalance of cytokines distribution may play a crucial role in the pathogenesis of nasal polyps.

Adult↗

PubMed2000

[Calcium activated non-selective cation channel in endothelial cell line ECV304 and inhibition of tumor necrosis factor-alpha].

OBJECTIVE: To study the character of non-selective cation channel in human umbilical cord vein endothelial cell line ECV304 and the effect of tumor necrosis factor-alpha (TNF-alpha) on channel activity. METHOD: Patch clamp technique was used to record single channel and whole cell currents. RESULTS: This channel can be activated by calcium, channel conductance was (19.74 +/- 2.35) pS and its Po was 0.260 +/- 0.006 (n = 5). 100 U/ml TNF-alpha inhibited channel activity, showing that conductance reduced to (10.69 +/- 4.68) pS and Po reduced to 0.230 +/- 0.051 (n = 5). Results in whole-cell configuration were consistent with that in cell-attached patches. Currents were obviously blocked by Cl- channel inhibitor anthracene-9-carboxylic acid (A9C). In order to testify the character of this channel further, KCl and NaCl were exchanged by K(+)-Aspartate in pipette solution. Under this condition, the single channel activities as before were recorded again. Its conductance was (18.33 +/- 2.98) pS(n = 8), and TNF-alpha as well as A9C could inhibit channel activity. But this channel activity could not be blocked by another Cl- channel blocker Zn2+. In the condition of K-Asparate replaced by CsCl in solution, identical channel activity as before could not be recorded. It seemed that Cs+ could not pass through this cation channel. CONCLUSION: It is inferred that calcium-activated non-selective-action channel recorded in endothelial cell ECV304, can be inhibited by TNF-alpha and A9C.

Anthracenes↗

PubMed2000

Inhibitory effect of fluvastatin on aortic intimal thickening in normocholesterolemic rabbits.

OBJECTIVE: The anti-atherosclerotic effect of fluvastatin at does insufficient to lower serum cholesterol on the catheter-induced intimal thickering and possible mechanism were investigated in abdominal aorta of rabbits. METHODS: Fifty-six rabbits were randomly divided into eight groups (n = 7, each). Fluvastatin was given mixed with food at daily dose of 8 mg/kg starting 5 days before catheterization. Light microscope, immunohistochemistry, transmission electron microscope and RT-PCR assay were applied to assess vascular smooth muscle cell (VSMC) proliferation and apoptosis, as well as oncogene expression in vascular wall. RESULTS: At day 10 and day 15 after catheter induced denudation intima/media (I/M) thickness ratio was obviously higher, and also the percentage of PCNA-positive cells and TUNEL-positive cells in media was significantly higher compared with controls. The intimal hyperplasia was mostly composed of alpha-SM-actin-positive cells. In rabbits given fluvastatin I/M ratio and the percentage of these positive cells significantly decreased compared with those without fluvastatin. The overexpression of proto-oncogene H-ras mRNA and decreased expression of anti-oncogene p53 mRNA were found after vascular injury, whereas fluvastatin significantly reduced H-ras mRNA and increased p53 mRNA expression. CONCLUSION: Proliferation of VSMC in the media and the migration to the intima can be inhibited, and apoptosis of VSMC be induced by short-term use of fluvastatin after balloon catheter denudation, independent of serum lipid change. The underlying mechanism is presumably associated with the influence of fluvastatin on oncogene expression in the injured vascular wall.

Animals↗

PubMed2000

Nitric oxide inhibits a rise of ATP-introduced cytosolic free Ca2+ concentration and release from intracellular stored Ca2+.

OBJECTIVE: The effects of ATP-introduced a rise in cytosolic free Ca2+ concentration and inhibition of nitric oxide were investigated. METHOD: Measurement of free Ca2+ ([Ca2+]i) of cultured rat tail arterial smooth muscle cells using Fura-2/AM dual excitation wavelength spectrofluorometer. RESULTS: There are two components of [Ca2+]i can be evoked by ATP. One part is Ca2+ entry from Ca2+ channel and formed a plateau. The another part is a peak that released from Ca2+ store. Both of them can be inhibited by NO. CONCLUSION: The ATP induced [Ca2+]i rise that release Ca2+ from both Insp3 and ryanochine receptors and Ca2+ entry through calcium channels. The inhibition of NO on ATP induced [Ca2+]i rise that was mediated by cGMP.

Adenosine Triphosphate↗