Biomedical subjects

D Luo

Publications and source records attributed to D Luo.

At least 37 records · Page 2Linked to original sources

PubMed2001

[Clinical and pathological characteristics of head and neck malignant melanoma].

OBJECTIVE: To investigate the clinical and pathological characteristics of head and neck malignant melanoma. METHODS: Sixty-eight cases of head and neck malignant melanoma were reviewed. There were 33 patients with melanoma in the nasal cavity and oral cavity, 35 patients with melanoma in the skin. The age fastigium of the patients was from 41 to 60 years. Surgical specimens in 52 cases and biopsy specimens in 16 cases were studied pathologically. S-100, HMB45 and NSE were examined immunohistochemically. RESULTS: Histopathology studies showed that the cell morphology was pleomorphic as well as polymorphic both in shape and size of the cells. Immunohistochemical studies helped diagnosis as all of the 42 melanoma specimens were posture for S-100 and 90.5% positive for HMB45. In 52 of the 68 cases, the tumor was excised surgically, with additional radiotherapy in 13 cases or chemotherapy in 21 cases. Ten cases were treated with radiotherapy alone. In 56 patients followed-up, 12 survived for 5 years, including 9 cases of skin melanoma and 3 cases of nasal and oral melanoma. CONCLUSION: The histo-pathological features of malignant melanoma vary significantly. Immunohistochemical staining helps diagnosis and differential diagnosis. The prognosis of malignant melanoma in nasal cavity and oral cavity is poor as compared to that in the skin of head and neck region.

Adolescent↗

PubMed2001

[A contour map segmentation for laser scanning confocal microscopic biomedical images].

We propose a contour map segmentation method for laser scanning confocal microscopic (LSCM) biomedical images. In this method, an image is first segmented into sub-regions by contour map. Then the sub-regions are merged from top to bottom or from bottom to top, according to a segmentation criterion of intensity homogeneity. The merging procedures continue until no region needs to be merged. The advantage of this method is that the objects with wide intensity ranges and different intensity homogeneity can be segmented properly. In this paper, the region segmentation by contour map is first addressed. Next a region merging according to a segmentation criterion of intensity homogeneity is presented, and then the design of a linear intensity homogeneity segmentation criterion is introduced. Two examples of image segmentation by this method are given at the end of this paper.

Algorithms↗

PubMed2001

[A study of hepatitis B virus(HBV) anti-genome and its inhibitory effect on HBV replication].

OBJECTIVE: To study the combination of triplex forming oligodeoxynucleotides (TFO) with hepatitis B virus gene and its effect on replication of HBV. METHODS: An oligodeoxynucleotide (TFO20) which can form triplex with SP1 sites in HBV core promoter was synthesized and was linked with biotin. Both the liposome-TFO20 and naked TFO20 were transfected to HepG2.2.15 cells, which was detected by SABC assay and showed signals that TFO20 was combined with HBV DNA. ELISA, reverse transcript (RT)-PCR and fluorescence quantitative PCR were used to investigate the change of HBV DNA, 3.5 kb/3.4 kb RNA, 2.4 kb/2.1 kb RNA, HBsAg and HBeAg in HepG2.2.15 cells before and after treatment with TFO20. RESULTS: The ratio of liposome-TFO20 and naked TFO20 transfected to HepG2.2.15 cells were 80% and 40%, respectively. TFO20 signals mainly distributed in the nucleus and cytoplasm. After treatment with TFO20, the level of HBV DNA was reduced from 10(7.01) to 10(4.94), while 3.5 kb/3.4 kb RNA, 2.4 kb/2.1 kb RNA, HBsAg and HBeAg were also reduced by 70.2%, 31.6%, 37.0%, 78.2% respectively. CONCLUSIONS: TFO20 can be transfected into cells by packing with liposome and can be combined with HBV DNA. TFO20 can effectively inhibit replication of HBV.

DNA Viruses↗

PubMed2001

[Research on the immunological cause of auricular pseudocyst].

OBJECTIVE: To elucidate the relationship between the auricular pseudocyst and the immunological function of patients. METHOD: The cyst fluid and blood sample had been detected for contents of IgG, IgA, IgM and complement C3 by radial immunodiffusion, immunocomplex (IC) contents by polyethylene glycol turbidimetry in 55 cases, anti-nuclear antibody (ANA) by immuno-fluorescent technique in 23 cases, extractable nuclear antibody (ENA) by immunotransfer technique in 24 cases. The frozen sections of cyst wall tissue of 24 cases had been detected for immunocomplex by immunoenzyme histochemistric method. The reactions were observed separately between the auricle tissue of healthy white rat, human embryo and cyst fluid, serum of patient and normal serum. RESULT: Contents of IgG, IgA, IgM and C3 in the cyst fluid were lower than the serum significantly (P < 0.01). No IC, ANA and ENA could been found both in serum and cyst fluid, but reactive immunocomplex was discovered on the auricle cartilagous tissue of patient, immunocomplex also be observed on human embryo aurical tissue when it reacted with cyst fluid, but complex hadn't be found when the auricle tissue of white rat and human embryo reacted with serum of patient and normal people. CONCLUSION: The reason of auricular pseudocyst may be related with the local autoimmune status of patient.

Adult↗

PubMed2001

[Histopathological observation of acute facial nerve impairment in rabbits].

OBJECTIVE: To investigate histopathological changes of acute facial nerve impairment. METHODS: Ligation of facial nerve outside stylomastoid foramen with 3-0 silk, observation of histopathological changes of facial nerve on the 1st day, 3rd day and 5th day after ligation. RESULTS: The facial nerve showed all kinds and various degrees of histopathological changes, from swelling to degeneration, in myeline and axon respectively. CONCLUSION: All kinds and various degrees of pathological changes have been observed in myeline and axon after the ligation of facial nerve in rabbits. This study demonstrates that such injuries to the facial nerve become increasingly serious as the ligation lasts day after day.

Animals↗

PubMed2000

Signaling pathways underlying muscarinic receptor-induced [Ca2+]i oscillations in HEK293 cells.

We have investigated the signaling pathways underlying muscarinic receptor-induced calcium oscillations in human embryonic kidney (HEK293) cells. Activation of muscarinic receptors with a maximal concentration of carbachol (100 microm) induced a biphasic rise in cytoplasmic calcium ([Ca2+]i) comprised of release of Ca2+ from intracellular stores and influx of Ca2+ from the extracellular space. A lower concentration of carbachol (5 microm) induced repetitive [Ca2+]i spikes or oscillations, the continuation of which was dependent on extracellular Ca2+. The entry of Ca2+ with 100 microm carbachol and with the sarcoplasmic-endoplasmic reticulum calcium ATPase inhibitor, thapsigargin, was completely blocked by 1 microm Gd3+, as well as 30-100 microm concentrations of the membrane-permeant inositol 1,4,5-trisphosphate receptor inhibitor, 2-aminoethyoxydiphenyl borane (2-APB). Sensitivity to these inhibitors is indicative of capacitative calcium entry. Arachidonic acid, a candidate signal for Ca2+ entry associated with [Ca2+]i oscillations in HEK293 cells, induced entry that was inhibited only by much higher concentrations of Gd3+ and was unaffected by 100 microm 2-APB. Like arachidonic acid-induced entry, the entry associated with [Ca2)]i oscillations was insensitive to inhibition by Gd3+ but was completely blocked by 100 microm 2-APB. These findings indicate that the signaling pathway responsible for the Ca2+) entry driving [Ca2+]i oscillations in HEK293 cells is more complex than originally thought, and may involve neither capacitative calcium entry nor a role for PLA2 and arachidonic acid.

Arachidonic Acid↗

PubMed2000

Characterization and transcriptional profiles of two rice MADS-box genes.

The plant MADS-box gene family plays a key role in plant development, especially in flower development. We designed degenerate primer according to the MADS-box conserved region and isolated two cDNA from rice, FDRMADS6 and FDRMADS7, which are homologous to AP1. RT-PCR expression analyses by using total RNA isolated from root, shoot and flower showed that the FDRMADS6 transcript was detectable only in flower while FDRMADS7 was expressed in all three tissues. In situ hybridization experiments indicated that at the early stage of rice flower development, the transcripts of FDRMADS6 and FDRMADS7 were detected in the spikelet apical meristem, which were same as AP1. At the late stage, when flower organ primordia started differentiating, the expression of FDRMADS6 appeared to be specifically localized in developing stamens and the pistil primordia, while the transcripts of FDRMADS7 were detectable abundantly throughout the organ primordia. Our results suggest the two MADS-box genes may be members of the AP1 family, but may have different functions.

Journal Article↗

PubMed2000

In vitro expression of hepatitis C virus non-structure 5 antigen in the HepG2 cell line.

To establish a cell line as a model system for HCV infection and propagation in vitro, a human HepG2 cell line was incubated with a HCV RNA positive serum. The sABC immunological techniques and gold-labeled colloid electron microscopy method were employed to examine the viral proteins in those cells. The HCV non-structure 5 antigen was first detected in the HepG2 cells 72 h after incubation. The antigen was continuously observed in the cytoplasm as well on the membrane of the HepG2 cells even after 1, 2, 3 and 4 weeks after incubation. The observation of HCV non-structure 5 antigen continuously expressed in the HepG2 cells strongly indicates that the cells may have been infected by HCV virus. Therefore, the HepG2 cell line may serve as a potential host for establishment of HCV infection and propagation in vitro.

Animals↗

PubMed2000

Study on biologic activity for membrane of normal bone marrow cells with infection of epidemic hemorrhagic fever virus.

Using DPH fluorescence probe, the membrane of normal bone marrow cells with infection of epidemic hemorrhagic fever virus (EHFV) was labeled. The membrane lipid fluidity was obviously decreased from the membrane lipid fluorescence polarization. The membrane lipid fluidity of lymphocyte, monocyte and neutrophilic granulocyte was dynamically observed. After culturing the cells for 1, 6, 24 and 72 h, it was found that all the membrane lipid fluidity of the infected cells was decreased obviously with the longer the culturing time, the more obvious it. Compared with the normal control groups, there was a significant difference statistically (P < 0.05-0.01). It was suggested that the decrease of the membrane lipid fludity of normal bone marrow cell with infection of EHFV had correlation with the degree of virus invading and cell-function injury.

Bone Marrow Cells↗

PubMed2000

Effects of three different Ca(2+) pump ATPase inhibitors on evoked contractions in rabbit aorta and activities of Ca(2+) pump ATPases in porcine aorta.

Using vascular smooth muscle, we describe the actions of three pharmacological tools, cyclopiazonic acid (CPA), thapsigargin (TG) and 2,5-di-(tert-butyl)-1,4-benzohydroquinone (tBHQ), which are presumed to act as selective inhibitors of the sarco-endoplasmic reticulum Ca(2+)-ATPases (SERCAs). In porcine aortic smooth muscle microsomes two Ca(2+)-ATPase activities have been described, one vanadate-sensitive and one vanadate-resistant, representing the Ca(2+)-ATPase activities of the plasma membrane and SERCAs, respectively. In agreement, CPA, TG and tBHQ, in the concentration range 0.1 microM to 0.1 mM, dose-dependently inhibit the Ca(2+)-ATPase activity only in the vanadate-resistant microsomes. However, 0.1 mM tBHQ also significantly inhibited the Ca(2+)-ATPase activity of vanadate-sensitive microsomes. In rabbit aortic rings, all three SERCA inhibitors produced a dose-dependant inhibition of contractions evoked by 20 mM caffeine or 1 microM phenylephrine (PE) in a Ca(2+)-free physiological solution. However, in PE-contracted rings, tBHQ (> or =30 microM) also significantly inhibited the ability of cromakalim to induce relaxation. In conclusion, the data suggest that CPA, TG and tBHQ can all act as selective SERCA inhibitors in both porcine and rabbit aortic smooth muscle. However, in contrast to CPA and TG, high concentrations of tBHQ can exhibit some nonspecific effects, which include inhibition of the plasma membrane Ca(2+)-ATPase and possibly K(+) channels regulated by cromakalim.

Animals↗

PubMed2000

Synthetic DNA delivery systems.

The ability to safely and efficiently transfer foreign DNA into cells is a fundamental goal in biotechnology. Toward this end, rapid advances have recently been made in our understanding of mechanisms for DNA stability and transport within cells. Current synthetic DNA delivery systems are versatile and safe, but substantially less efficient than viruses. Indeed, most current systems address only one of the obstacles to DNA delivery by enhancing DNA uptake. In fact, the effectiveness of gene expression is also dependent on several additional factors, including the release of intracellular DNA, stability of DNA in the cytoplasm, unpackaging of the DNA-vector complex, and the targeting of DNA to the nucleus. Delivery systems of the future must fully accommodate all these processes to effectively shepherd DNA across the plasma membrane, through the hostile intracellular environment, and into the nucleus.

Animals↗

PubMed2000

Enhancement of transfection by physical concentration of DNA at the cell surface.

Efficient DNA transfection is critical for biological research and new clinical therapies, but the mechanisms responsible for DNA uptake are unknown. Current nonviral transfection methods, empirically designed to maximize DNA complexation and/or membrane fusion, are amenable to enhancement by a variety of chemicals. These chemicals include particulates, lipids, and polymer complexes that optimize DNA complexation/condensation, membrane fusion, endosomal release, or nuclear targeting, which are the presumed barriers to gene delivery. Most chemical enhancements produce a moderate increase in gene delivery and a limited increase in gene expression. As a result, the efficiency of transfection and level of gene expression after nonviral DNA delivery remain low, suggesting the existence of additional unidentified barriers. Here, we tested the hypothesis that DNA transfection efficiency is limited by a simple physical barrier: low DNA concentration at the cell surface. We used dense silica nanoparticles to concentrate DNA-vector (i.e. DNA-transfection reagent) complexes at the surface of cell monolayers; manipulations that increased complex concentration at the cell surface enhanced transfection efficiency by up to 8.5-fold over the best commercially available transfection reagents. We predict that manipulations aimed at optimizing DNA complexation or membrane fusion have a fundamental physical limit; new methods designed to increase transfection efficiency must increase DNA concentration at the target cell surface without adding to the toxicity.

Animals↗

PubMed2000

Molecular mimicry of human tumor antigen by heavy chain CDR3 sequence of the anti-idiotypic antibody.

We isolated and characterized an anti-idiotype monoclonal antibody (AR42.1) which is capable of mimicking a distinct and specific epitope of MUC-1 antigen. The cDNA sequences coding for the AR42.1 variable regions were determined. We found significant amino acid homology between complementary determining regions 3 (CDR3) in the heavy chain of AR42.1 and the determinant epitope sequence of MUC-1. This 10 amino acid sequence may represent an "internal image" of the anti-idiotype antibody to the MUC-1 antigen, and could be used for development of a MUC-1 surrogate for immunotherapy.

Animals↗

PubMed2000

Effects of Bcl-2 and Bcl-XL protein levels on chemoresistance of hepatoblastoma HepG2 cell line.

The ratio between apoptotic promoters and repressors in the Bcl-2 family determines the chemosensitivity of cells to apoptotic stimuli. This study examines the chemoresistance of a transfected human hepatoblastoma HepG2 cell-line during Taxol and Doxorubicin application. Sense bcl-2, and anti-sense bcl-XL gene fragments were separately inserted into HepG2 cells via stable transfection. The expression profile of the Bcl-2 family proteins was determined by Western blot analysis. Chemosensitivity of the transfected cells was measured by Trypan blue exclusion assay and XTT reduction assay during drug application. In the absence of Bax protein, HepG2 cells with elevated Bcl-2 protein levels did not exhibit any significant increase in chemosensitivity towards the drugs. Transfected cells with reduced Bcl-XL levels became more sensitive to the drugs, and a significant difference in IC50 values was observed. The chemosensitivity of HepG2 cells to Taxol and Doxorubicin was not affected by Bcl-2 levels, while reduction of Bcl-XL levels rendered the cells more sensitive to the drugs. This suggests that the Bcl-2 protein alone could not protect HepG2 cells from drug-induced apoptosis, and that the Bcl-XL protein may be a target for gene therapy in hepatoblastoma treatment.

Antineoplastic Agents↗

PubMed2000

Measuring continuity of elders' posthospital care.

Continuity of care is a critical component of quality patient care, yet the paucity of reliable and valid measures of continuity of care make it difficult to ascertain the extent to which continuity has been achieved. The purpose of this article is to describe the development of an instrument to measure continuity of care that incorporates the perspectives of elders hospitalized for a chronic illness and their family caregivers. The instrument was used, and its reliability and validity examined, in a series of studies related to elders' posthospital transition. Elders in the studies ranged in age from 55 to 94 years. The findings supported content and construct validity, internal consistency reliability, and ability to detect changes in the same subjects at different points in time for the care management and services subscales. With further refinement, the continuity of provider and conflicting information subscales might also facilitate assessment of care continuity.

Aftercare↗

PubMed2000

[Mutations of Q20L and G247D improved the specific-activity and optimum pH of glucose isomerase].

The mutants of Q20L and G247D of glucose isomerase (GI) were constructed by in vitro site-directed mutagenesis of GI gene with double-primersmethod. The recombinant plasmids pTKD-GIQ20L and pTKD-GIG247D were expressed in E. coli K38 strain. The comparison experiments of mutant enzymes with wild-type GI showed that: (1) the optimum temperature of GIQ20L was decreased by 5 degrees C. Its thermostability was only 78% half-time of the wild type. But its substrate affinity was enhanced. (2) The specific-activity of GIG247D was increased by 33%, and the optimum pH was lowered by 0.6 unit. However, the thermostability of GIG247D was decreased. We supposed, based on the above facts and 0.19 nm resolution crystal structure of SM33GI, that Gln20 locates between alpha 0-helix and alpha 1-helix, the substitution of hydrophobic side chain of Leu for hydrophilic side chain of Gln may enhance the hydrophobic interaction of the molecular surface, leading to the decrease of the stability and thermostability of GIQ20L. Gly247 which is the last amino acid of a beta-sheet from 242 to 247 residues locates in the active core of GI. After replacement, Asp247 which has strong negative electricity may change the electrostatic distribution and influence the charge transfer processes of the active core. So the specific-activity of GIG247D was increased. The introduced charge could alter the pKa of dissociable groups and make the optimum pH lower. In addition, the side chain of Asp247 seems to be very crowded in the surrounding space conformation and is easy to exclude with the other side chains, therefore influences the stability of beta-sheet. Furthermore, Asp247 is in the vicinity of the interface of subunits, so it could interfere with the stability of the interaction between subunits. Thus, the GIG247D decreased the thermostability of SM33GI. The higher enzyme activity and the lower optimum pH will be very useful for industrial production of GI.

Aldose-Ketose Isomerases↗

PubMed2000

Anti-hepatoma activity of taxol in vitro.

AIM: To investigate the in vitro anti-hepatoma activity of taxol against SMMC-7721 human hepatoma cells. METHODS: The hepatoma cell growth was measured by MTT-microculture tetrazolium assay. Cell-cycle kinetics and apoptosis were analyzed by flow cytometry and microscopic examination. RESULTS: Taxol inhibited the hepatoma cell growth in concentration- and time-dependent manners with IC50 of 18.96 nmol.L-1. Marked cell accumulation in G2/M phase and multinucleated cells were also observed after treatment with taxol 10 nmol.L-1. In addition, taxol at 10 nmol.L-1 could induce the apoptosis of hepatoma cells. CONCLUSION: Taxol suppresses the growth of SMMC-7721 human hepatoma cells in vitro by causing cell-cycle arrest, aberrant mitosis, and apoptosis of the human hepatoma cells.

Antineoplastic Agents, Phytogenic↗

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↗