Biomedical subjects

D Luo

Publications and source records attributed to D Luo.

At least 55 records · Page 3Linked to original sources

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

Molecular epidemiologic study of Mycoplasma genitalium infection in high risk populations of sexually transmitted diseases in China.

OBJECTIVE: To detect Mycoplasma genitalium (Mg) infection in high risk populations of sexually transmitted diseases (STDs) from several cities in China and to clarify the possible role of Mg in the pathogenesis of non-gonococcal urethritis. METHODS: Polymerase chain reaction (PCR) based on 2 pairs of primers, one for Mg-Pa (adhesion protein) and the other for 16S-rRNA (Mycoplasma genera) was used to detect Mg infection. Urogenital specimens of different high risk populations and urethritis patients, were collected from the Guangdong, Kunming, Shanghai, Nanjing, and Changzhou areas. RESULTS: The positive detection rate of Mg-DNA in high risk populations of STDs was significantly higher than that of the control group (chi 2 = 7.82, P < 0.01). The positive detection rates in Guangdong STD clinics and promiscuous persons from Kunming were higher than those from the Shanghai, Nanjing, and Changzhou areas (chi 2 = 8.54, P < 0.01 and chi 2 = 5.89, P < 0.05). Mg DNA could be detected in those patients without other relevant pathogens. Some patients were simultaneously infected with Mg and other microbes, such as Chlamydia trachomatis and/or Ureaplasma urelyticum. The positive Mg-DNA detection rate in patients with urethritis symptoms was higher than in patients without the symptoms (chi 2 = 11.68, P < 0.01). CONCLUSION: Mg infection exists in high risk populations of STDs in China, and the Mg infection rate is different among different high risk groups.

Adolescent↗

PubMed1999

Transcriptional induction of stromelysin-3 in mesodermal cells is mediated by an upstream CCAAT/enhancer-binding protein element associated with a DNase I-hypersensitive site.

Stromelysin-3 (ST3) is a matrix metalloproteinase whose synthesis is markedly increased in stromal fibroblasts of most invasive human carcinomas. In the present study, we have investigated the molecular mechanisms by which high levels of ST3 expression can be induced. In contrast to the early and transient induction of interstitial collagenase by 12-O-tetradecanoylphorbol-13-acetate (TPA), the fibroblastic induction of ST3 was found to be delayed and to require protein neosynthesis. We demonstrated that this induction is transcriptional and does not result from changes in RNA stability. By looking next to promoter regions accessible to DNase I upon gene induction, we have identified two distal elements and have characterized their role in the transcriptional regulation of ST3. The first one is a TPA-responsive element that controls the base-line ST3 promoter activity but is not required for its activation. We demonstrate that ST3 gene induction is actually mediated by the second element, a C/EBP-binding site, by showing: (i) that this element becomes accessible in cells induced to express ST3, (ii) that endogenous C/EBPbeta binds to the ST3 promoter, and (iii) that this binding leads to ST3 transcriptional activation. Our study provides new insights into the regulation of ST3 and suggests an additional role for C/EBP transcription factors in tissue remodeling processes associated with this MMP.

CCAAT-Enhancer-Binding Proteins↗

PubMed1999

Control of organ asymmetry in flowers of Antirrhinum.

Organ asymmetry is thought to have evolved many times independently in plants. In Antirrhinum, asymmetry of the flower and its component organs requires cyc and dich gene activity. We show that, like cyc, the dich gene encodes a product belonging to the TCP family of DNA-binding proteins that is first expressed in the dorsal domain of early floral meristems. However, whereas cyc continues to be expressed throughout dorsal regions, expression of dich eventually becomes restricted to the most dorsal half of each dorsal petal. This correlates with the effects of dich mutations and ectopic cyc expression on petal shape, providing an indication that plant organ asymmetry can reflect subdomains of gene activity. Taken together, the results indicate that plant organ asymmetry can arise through a series of steps during which early asymmetry in the developing meristem is progressively built upon.

Amino Acid Sequence↗

PubMed1999

Muscarinic receptor-mediated calcium signaling in spiral ganglion neurons of the mammalian cochlea.

Using indo-1 microspectrofluorometry, we examined the effects of cholinergic agonists on the concentration of intracellular Ca(2+) ions ([Ca(2+)](i)) in spiral ganglion neurons, isolated from rat cochleae at different stages of post-natal development (from P3 to P30). Extracellular application of acetylcholine (ACh) or carbamylcholine generated a rapid and transient increase in [Ca(2+)](i). The ACh concentration-response curve indicated an apparent dissociation constant (K(d)) of 8 microM and a Hill coefficient of 1.0. Removing extracellular free Ca(2+) did not suppress the ACh-induced Ca(2+) responses suggesting an intracellular Ca(2+)-release mechanism. When we compared the cholinergic response at different stages of postnatal development, there were no significant differences on the aspect of the Ca(2+) response and the percentage of responsive neurons, which ranged between 50 and 65% per cochlear preparation. The application of muscarine triggered reversible Ca(2+) responses similar to those observed with ACh, with an apparent K(d) of 10 microM and a Hill coefficient of 1.0. The cholinergic-induced Ca(2+)pirenzepine. Nicotine (10 to 100 microM) did not evoke Ca(2+) responses and the nicotinic antagonist curare (10 microM) did not block the ACh-evoked responses. The present study is the first direct demonstration of functional muscarinic receptors (mAChRs) in spiral ganglion neurons. These mAChRs activated by the cholinergic lateral efferent system may participate in the regulation of the electrical activity of the afferent auditory fibers contacting the inner hair cells.

Acetylcholine↗

PubMed1999

Smoking hygiene: a study of attitudes to passive smoking.

AIM: To study the attitudes and knowledge of adults in the Wellington area about the effects of passive smoking and measures to reduce exposure to smoke. METHODS: A sample of 200 people, randomly selected in the Wellington area, answered a telephone survey on passive smoking. RESULTS: Of the 200 respondents, 160 (80%) were males, 40 (20%) were females and approximately one-third (30%) were smokers. Most people (85.5%) thought public and private areas should be smoke-free when there were children around, but only half (53.5%) thought that smoking should be banned in cars when there are passengers. Most people (92.5%) correctly defined passive smoking. Half were aware that passive smoking negatively contributed to all the following diseases (asthma, cancer, heart disease, respiratory problems) and cot death but a higher percentage identified cancer (75.5%) and cot deaths (68.5%) specifically. Most smokers reported that they smoke at home or in their cars rather than in public places. Half the smokers (50.9%) did not smoke in front of children; a further 17.3% reported that they smoked less. CONCLUSIONS: In this sample there was a relatively low level of awareness of the effects of passive smoking on health and a high prevalence of smoking in the presence of children. Smokers and non-smokers were almost equally divided on whether there should be a law restricting smoking in private cars, although the majority agreed that cars carrying children should be smoke-free. Public health efforts to reduce the harm from passive smoking should be focused on discouraging smoking, in settings in which children are exposed, including private cars when children are passengers.

Attitude to Health↗

PubMed1999

Pit cells (Hepatic natural killer cells) of the rat induce apoptosis in colon carcinoma cells by the perforin/granzyme pathway.

The high mortality of colon cancer is to a large extent caused by the frequent occurrence of liver metastasis. This is remarkable, because the liver harbors two distinct cell populations that can eliminate invading cancer cells, namely hepatic natural killer (NK) cells and Kupffer cells. These hepatic NK cells, known as pit cells, are the most cytotoxic cells of the naturally occurring NK cells. However, the mechanism by which pit cells eliminate tumor cells is largely unknown. Because we recently found an indication that apoptosis is involved, we tried to assess the role of this mode of cell death using an in vitro system with isolated pure pit cells (>90%) and CC531s cells, a rat colon carcinoma (CC) cell line. Pit cells induced apoptosis in CC531s cells as shown by quantitative DNA fragmentation, agarose gel electrophoresis, and different modes of microscopy. When extracellular Ca2+ was chelated by ethylene glycol-bis(beta-aminoethyl ether)-N,N,-tetraacetic acid (EGTA) during coincubation or when the pit cells were preincubated with the granzyme inhibitor 3,4-dichloroisocoumarin (DCI), the induction of apoptosis was abolished. These results show that pit cells use the Ca2+-dependent perforin/granzyme pathway to induce apoptosis in the CC531s cells, and not the alternative Ca2+-independent Fas pathway. To further exclude the possibility of the involvement of the Fas pathway, we treated CC531s cells with recombinant Fas ligand. This treatment did not result in the induction of apoptosis, indicating that CC531s cells are resistant to Fas-mediated apoptosis. We conclude therefore that pit cells induce apoptosis in CC cells in vitro by the perforin/granzyme pathway.

Animals↗

PubMed1999

Study on IL-4, IL-5 and IL-10 in liver and bone marrow of mice infected with Schistosomiasis Japonica.

To compare Th2 cytokines levels in livers and bone marrow of mice infected with Schistosomiasis Japonica and understand their implication, ABC immunohistochemical staining technique and multimedia pathologic pictures analysis were used to detect the IL-4, IL-5 and IL-10 derived from livers and bone marrow of infected mice. Results showed that in the livers of infected mice, IL-4, IL-5 and IL-10 were obviously increased over time. The level of IL-4 was increased most among the 3 indicators. In bone marrow of infected mice, however, even though IL-4 was slowly increased over time, it was lower than that of livers in 10th and 12th week. The level of IL-5 was higher than that of livers during 12th weeks. Before 10th weeks IL-10 was elevated. After 12th week IL-10 was decreased and obviously lower than that of livers. It is concluded that in mice infected with Schistosomiasis Japonica, the immune response occurred mainly in the liver. Therefore, in bone marrow, IL-5 showed obvious auto-secretion. It might be related to its biological ability to induce B cell division and eosinophil differentiation.

Animals↗

PubMed1999

Relationship between the clinical features and the viral antigen in the extremity blood of the patients with hemorrhagic fever with renal syndrome.

The direct immunogold silver staining (D-IGSS) method was used to detect the viral antigen in the extremity blood of 67 cases of hemorrhagic fever with renal syndrome. The positive rate of viral antigen was the highest during the fever, hypotension and oligouria phrase; and the rate dropped gradually during the polyuria and convalescent phase. It is suggested that clinical staging was positively related with the percentage of the viral antigen positive cells (P < 0.001). It is concluded that the positive rate was related to the extent of the injuries by direct viral attack and immune reaction. The D-IGSS was proved to be fast, simple, economical, with high sensitivity and specificity.

Adolescent↗

PubMed1999

Involvement of LFA-1 in hepatic NK cell (pit cell)-mediated cytolysis and apoptosis of colon carcinoma cells.

BACKGROUND/AIMS: Previous studies have shown that hepatic natural killer (NK) cells, also called pit cells, have a higher cytotoxicity against certain tumor cells and have a higher expression of the cell adhesion molecule CD11a as compared with blood NK cells. We further investigated the involvement of the adhesion molecules, reported to be involved in target cell killing by blood NK cells, in pit cell-mediated colon carcinoma cell killing. METHODS: 51Cr-release and DNA fragmentation were used to quantify target cell lysis and apoptosis, respectively. Adhesion of pit cells to CC531s monolayers was quantitated. RESULTS: Flow cytometric analysis showed that pit cells expressed CD2, CD11a, CD18 and CD54. CC531s cells expressed only CD54. Treatment of freshly isolated pit cells with monoclonal antibodies (mAbs) to CD11a and CD18 inhibited not only the pit cell-mediated CC531s cytolysis but also the pit cell-induced apoptosis of CC531s cells. The combination of mAbs to CD11a, CD18 and CD54 further increased the inhibition of pit cell-mediated CC531s cytolysis and apoptosis. Anti-CD2 mAb did not affect these processes. The binding of pit cells to CC531s cells was also inhibited by anti-CD11a, and CD18 mAbs, but not by anti-CD2 mAb. Anti-CD54 mAb reduced the target cell killing and the binding only slightly. CONCLUSIONS: These results indicate that CD11a/CD18 (LFA-1) present on pit cells plays an important role in pit cell-mediated target cell adhesion, lysis and apoptosis. This finding might explain why pit cells, which have a higher expression of LFA-1 as compared to blood NK cells, are more cytotoxic against tumor cells as compared to blood NK cells.

Animals↗

PubMed1999

Controlled DNA delivery systems.

PURPOSE: Genes are of increasing interest as pharmaceuticals, but current methods for long-term gene delivery are inadequate. Controlled release systems using biocompatible and/or biodegradable polymers offer many advantages over conventional gene delivery approaches. We have characterized systems for controlled delivery of DNA from implantable polymer matrices (EVAc: poly (ethylene-co-vinyl acetate)) and injectable microspheres (PLGA and PLA: poly (D, L-lactide-co-glycolide) copolymer and poly (L-lactide), respectively). METHODS: Herring sperm DNA and bacteria phage lambda DNA were encapsulated as a model system. Released DNA concentration was determined by fluoroassays. Agarose electrophoresis was used to determine the dependence of release rate on DNA size. The Green Fluorescent Protein (GFP) gene was used to determine the integrity and functionality of released DNA. RESULTS: Both small and large DNA molecules (herring sperm DNA, 0.1-0.6 kb; GFP, 1.9 kb; lambda DNA, 48.5 kb) were successfully encapsulated and released from EVAc matrices, and PLGA or PLA microspheres. The release from DNA-EVAc systems was diffusion-controlled. When co-encapsulated in the same matrix, the larger lambda DNA was released more slowly than herring sperm; the rate of release scaled with the DNA diffusion coefficient in water. The chemical and biological integrity of released DNA was not changed. CONCLUSIONS: These low cost, and adjustable, controlled DNA delivery systems, using FDA-approved biocompatible/biodegradable and implantable/injectable materials, could be useful for in vivo gene delivery, such as DNA vaccination and gene therapy.

Biodegradation, Environmental↗

PubMed1999

Safety of nifedipine in angina pectoris: a meta-analysis.

-Our objective was to compare cardiovascular event rates in patients with stable angina receiving nifedipine as monotherapy or combination therapy and in active drug controls. A MEDLARS search of published articles from 1966 to 1995 in English, French, German, Italian, or Spanish, supplemented by a manual search of bibliographies, identified 60 randomized controlled trials that met protocol criteria. Blinded articles were extracted by 2 physicians. The pooled risks of death, withdrawal, and cardiovascular event were computed and expressed as odds ratios (ORs) for all nifedipine formulations and relative to same study control drug regimens. Thirty cardiovascular events were reported in 2635 nifedipine exposures (1.14%) and 19 events in 2655 other active drug exposures (0.72%). Unadjusted ORs for nifedipine versus controls were 1.40 (95% CI, 0.56 to 3.49) for major events (death, nonfatal myocardial infarction, stroke, revascularization procedure), 1.75 (95% CI, 0.83 to 3.67) for increased angina, and 1.61 (95% CI, 0.91 to 2.87) for all events (major events plus increased angina). Episodes of increased angina were more frequent on immediate-release nifedipine (OR, 4.19 [95% CI, 1.41 to 12.49]) and on nifedipine monotherapy (OR, 2.61 [95% CI, 1.30 to 5.26]). The OR for immediate-release nifedipine was significantly higher than that for sustained-release/extended-release nifedipine (P=0.001), and the OR for nifedipine monotherapy was higher than that for nifedipine combination therapy (P=0.03). Increased risks of cardiovascular events in patients with stable angina on nifedipine were due primarily to more episodes of increased angina, confined to the immediate-release formulation and to nifedipine monotherapy.

Adrenergic beta-Antagonists↗

PubMed1999

L-selectin expression enhances clonogenesis of CD34+ cord blood progenitors.

L-selectin, a surface adhesion glycoprotein expressed on leukocytes, has a well-established role in mediating inflammation and lymphocyte recirculation. Recent evidence suggests that L-selectin may also influence hematopoiesis. We observed that a greater proportion of CD34+ cells express L-selectin in cord blood compared with adult bone marrow, and we hypothesized that L-selectin expression is associated with enhanced clonogenic properties. To test this, we compared CD34+/L-selectin+ cells with CD34+/L-selectin- cells in hematopoietic clonogenic assays. From CD34+/L-selectin+ cell cultures, we observed a 3-fold increase of d 12-14 colony-forming unit-granulocyte/macrophage and multipotent progenitor cells, and a 5-fold enhancement of primitive d 21 high proliferative potential colony-forming cells compared with the progeny of CD34+/L-selectin- cells. We conclude that CD34+ cord blood cells expressing L-selectin are enriched in their clonogenic activity compared with cell fractions lacking L-selectin expression.

Adult↗

PubMed1999

Genetic control of trichome branch number in Arabidopsis: the roles of the FURCA loci.

We are using trichome (hair) morphogenesis as a model to study how plant cell shape is controlled. During a screen for new mutations that affect trichome branch initiation in Arabidopsis, we identified seven new mutants that show a reduction in trichome branch number from three branches to two. These mutations were named furca, after the Latin word for two-pronged fork. These seven recessive mutations were placed into four complementation groups that define four new genes: FURCA1, FURCA2, FURCA3 and FURCA4. The trichome branch number phenotype indicates that the FURCA genes encode positive regulators of trichome branch initiation. Analysis of double mutants suggests that primary and secondary branch initiation events are not genetically distinct, but rely on the levels of partially redundant groups of regulators of trichome branch initiation. Based on the analysis of both epistatic and additive genetic interactions between the FURCA genes and other genes that control trichome branch number, we propose a model that explains how these genes interact to control trichome branch initiation. This model successfully predicts the phenotypes of all the single and double mutants examined and suggests points of control of the trichome branch pathway.

Arabidopsis↗

PubMed1999

[The expression of p16, CDK4 and pRb in hepatocellular carcinomas].

OBJECTIVE: To make an analysis of the expression of p16 gene, CDK4 and retinoblastoma protein(pRb) in human hepatocellular carcinoma(HCC). METHODS: Application of immunohistochemistry to 40 cases of HCC and their adjacent liver tissues. RESULTS: The abnormal expressions of p16, CDK4 and pRb were 94.44%(34/36), 40.00%(16/40) and 45.71%(16/35) respectively. Rb protein was strongly stained in 13/34(38.23%) cases lacking or weak staining with p16, which showed a negative relation between the expressions of Rb and p16. The abnormal expressions of both p16 and Rb were 15/34(44.11%) cases, indicating that except p16, there are some other ways to regulate Rb. In 14 cases of CDK4 overexpression, most of them (92.85%) presented p16 aberration, 50.00% of them were observed with pRb abnormal expression, 46.15% of them were along with the alterations of both p16 and pRb. There was no significant correlation between p16 or CDK4 or pRb abnormal expression and HCC malignant grade. CONCLUSION: The data show that the aberrant expression of p16, CDK4 and pRb may play a role in the carcinogenesis of HCC. The changes of p16 expression is prominent.

Carcinoma, Hepatocellular↗

PubMed1999

Expression of Bcl-2 family proteins during chemotherapeutic agents-induced apoptosis in the hepatoblastoma HepG2 cell line.

This study demonstrates that two anticancer drugs, taxol and doxorubicin (Dox), can kill human hepatoblastoma HepG2 cells in a dose-dependent manner via the induction of apoptosis. Characteristic events, including externalization of phosphatidylserine, cytoplasmic shrinkage, chromatin condensation and DNA degradation, were observed in a large majority of the drug-treated cells. DNA fragmentation showed that a ladder of DNA fragments of approximately 200 bp multiples was observed in taxol-treated, but not in Dox-treated, cells. In addition, the expression patterns of Bcl-2 family members during taxol or Dox treatment were investigated. Results from Western blot analysis indicated that HepG2 cells did not express either the death repressor Bcl-2, or the death promoters Bcl-XS and Bax. However, during the apoptotic process one death repressor, Bcl-XL, and two death promoters, Bak and Bad, were expressed. The expression levels of Bcl-XL and Bak remained unchanged, whereas the level of Bad was down-regulated. As the ratio between death repressors and death promoters in the Bcl-2 family will determine the sensitivity of cells to apoptotic stimuli, the findings suggest that the changed expression patterns of Bcl-2 family proteins caused by anticancer drugs in liver cancer cells may be involved in chemoresistance.

Antineoplastic Agents↗

PubMed1999

[Prevention and treatment of eyelid retraction and ectropion following lower eyelid blepharoplasty with tarsal tuck procedure].

OBJECTIVE: To prevent or decrease eyelid retraction and ectropion following lower eyelid blepharoplasty. METHODS: The tarsal tuck procedure was performed during lower eyelid blepharoplasty to tighten the lower eyelid. This method had been used since 1991. RESULTS: After the operation, the lower eyelid was tensional and steady. The complications of eyelid retraction and ectropion were diminished. CONCLUSION: The pathologic basis of the eyelid bag is that the supporting tissues become lax so that the lower eyelid and lateral canthus move downwards. The exact aim of the tarsal tuck procedure is to correct these pathologic changes.

Blepharoplasty↗

PubMed1999

Isolation and identification of Mycoplasma genitalium from high risk populations of sexually transmitted diseases in China.

OBJECTIVE: To investigate Mycoplasma genitalium (Mg) infection in high risk populations of sexually transmitted diseases (STDs) in China by means of culture, Mg-DNA detection, observation under an electron microscope (EM) and an atomic force microscope (AFM). METHODS: 227 urogenital specimens taken from both patients in clinics and high risk populations of STDs in Beijing, Nanjing and Shanghai areas were cultured in SP-4 medium for isolation of Mg. Suspicious positive strains were identified first by PCR technique which could amplify the special DNA fragments of Mg adhesion protein (Mg-Pa) and 16S-rRNA sequences. The morphologic features of Mg were observed under EM and AFM. RESULTS: Eight strains were isolated from the 227 specimens, the total positive rate was 3.52%. The isolated strains met the criteria of growth and metabolic conditions required by Mg. Specific fragments of Mg-DNA (374 bp based on Mg-Pa and 402 bp on 16S-rRNA primers, respectively) could be amplified from both the isolates and the genital secretions. Under EM and AFM, Mg showed different shapes, including flask, pear, spindle and globe shape. The typical shape of Mg was flask or pear shape with projecting neck portion and broadened terminal structure under EM and with constrictive ring between the neck and body under AFM. CONCLUSION: Mg infection exists in high risk populations of STDs in China. We highly suggest the use of AFM in dermatological study.

Cervix Uteri↗