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Biomedical subjects

M Fan

Publications and source records attributed to M Fan.

At least 73 records · Page 4Linked to original sources
PubMed1999

Immunolabeling of the major cell surface protein antigen of Streptococcus sobrinus with monoclonal antibody.

OBJECTIVE: The purpose of this study was to determine the accessibility of monoclonal antibody (McAb), specific for the major cell surface protein antigen (PAg) of Streptococcus sobrinus, to the surface of its native epitopes. MATERIALS AND METHODS: An indirect immunogold labeling technique was used to detect the reaction of McAb with S. sobrinus 6715. The reactions of polyclonal antibodies (PcAbs) against S. sobrinus 6715 or PAg with S. sobrinus 6715, S. mutans Ingbritt C and S. rattus BHT were studied as controls. RESULTS: The results indicated that PAg was localized on the outer cell surface of S. sobrinus, and McAb was reactive with only a few epitopes of the cell surface, whereas PcAbs were found to be reactive with more epitopes. CONCLUSIONS: McAb was specific for the PAg, but there was cross-reaction with S. mutans. Also there seemed to be an association between the fuzzy coat on the surface of S. sobrinus and PAg.

Adhesins, Bacterial↗
PubMed1999

[Apoptosis in the developing tooth of postnatal rat].

OBJECTIVE: To study apoptosis in the developing tooth of postnatal rat. METHODS: Transferase-mediated, dUTP-biotin nick end labeling(TUNEL) method was utilized to label the paraffin sections of the lower and upper jaws taken from 3 days and 9 days of postnatal rats. RESULTS: Positive stains for the presence of apoptosis were observed in ameloblasts, especially in cervical loop region, and stellate reticulum cells. Odontoblasts at the tip of developing molars in which physiological osteodentin was forming were strongly positive. A few dental pulp cells were labeled. CONCLUSION: Apotosis is a biological process, which play an important role in the formation of teeth. Apoptosis may take place in epithelial derived cells as well as mesenchymal-derived cells.

Animals↗
PubMed1999

[Effect of monoclonal antibody on the colonization of Streptococcus sobrinus and the development of dental caries in rats].

OBJECTIVE: To investigate the effect of local application of monoclonal antibody (McAb) raised against the major cell surface protein antigen of streptococcus sobrinus (PAg) on the colonization of rats' teeth by Streptococcus sobrinus (S. sobrinus) and the development of dental caries. METHODS: 30 wistar rats were divided into three groups: group I received McAb against PAg; group II received unrelated mice ascites; group III received PBS. They were applied on six occasions. After three times of application, streptomycin resistant S. sobrinus 6715 were inoculated onto the teeth and the rats were fed with caries-inducing diet 2000#. The number of colonized S. sobrinus were counted and the presence of caries was examined by the procedure of Keyes'. RESULTS: There was a significant lower level of colonization by S. sobrinus and lower mean caries scores treated with McAb compared with the control groups. CONCLUSION: Local passive immunization with McAb against PAg may be an effective way to prevent the colonization by implanted S. sobrinus and the development of dental caries.

Animals↗
PubMed1999

[Effects of monoclonal antibody against the major cell surface protein on salivary agglutinin mediated aggregation of Streptococcus sobrinus].

OBJECTIVE: To investigate the effects of monoclonal antibody on salivary agglutinin-mediated aggregation of Streptococcus sobrinus in vitro. METHODS: Bacterial aggregation inhibition was measured under OD650 at 10 minutes intervals for 1 hour. RESULTS: It showed that the McAb ZS2/286 raised against the PAg of S. sobrinus 6715 could inhibit the aggregation by some degree, but the effect was not significant. CONCLUSION: The McAb ZS2/286 might not bind directly to the functionally important region of PAg related to aggregation.

Agglutinins↗
PubMed1998

Serial sectioning of sentinel nodes in patients with breast cancer: a pilot study.

BACKGROUND: Recent reports indicate that the sentinel node, defined as the first regional lymph node to receive lymphatic fluid from the breast, accurately represents the metastatic status of the primary breast cancer. However, routine single section examination of the regional nodes, including the sentinel node, underestimates the true incidence of metastases. The goal of this study is to determine whether multiple sectioning of sentinel nodes will detect occult metastases in operable breast cancer. METHODS: Nineteen patients with invasive breast cancers were injected with technetium-99m sulfur colloid solution around the tumor or at the biopsy site before lumpectomy and axillary lymph node dissection (ALND) or mastectomy. The labeled sentinel lymph nodes (SLND) were bivalved, and a central section was taken for hematoxylin and eosin (H & E) examination. The sentinel nodes of 13 patients, which were reported to be negative for metastases, were serially sectioned at 0.5-mm intervals and stained with H & E and a cytokeratin stain, CAM 5.2. RESULTS: In the 13 node-negative patients, occult metastases were found in the sentinel nodes of 3 patients (23%). Two were seen on H & E and one by cytokeratin stain. The mean numbers of SLND and ALND in this series were 2.6 and 12.5, respectively, and the average number of sections for the two groups was 14 and 1, respectively. CONCLUSION: Multiple sectioning of the sentinel node or nodes detects occult metastases and changes the staging of breast cancer.

Adult↗
PubMed1998

Sentinel node biopsy in the staging of breast cancer.

BACKGROUND: The role of axillary lymph node dissection (ALND) in breast cancer is currently being reevaluated. Sentinel node biopsy (SNB) holds promise for replacing full dissection in a large number of patients with breast cancer. MATERIALS: We evaluated SNB utilizing an intraoperative gamma probe localization technique following injection of technetium sulfur colloid in 80 patients with primary breast cancer and clinically negative axillae. Forty-eight patients were evaluated at Baptist Medical Center, Montgomery, Alabama, and 32 at Rush-Presbyterian-St. Luke's Medical Center in Chicago, Illinois. RESULTS: At least one sentinel node was found in 70 of the 80 patients (88%). One patient had a sentinel node in both the axilla and internal mammary chain. The remainder had axillary sentinel nodes only. The sentinel nodes accurately predicted the status of the axilla in 69 of the 70 patients (99%). One of 14 node-positive patients would have been missed with sentinel node biopsy alone, for a false negative rate of 7%. Four node-positive patients would have been missed with routine ALND without serial sectioning (SS) and immunohistochemical staining (IH) of the sentinel node. CONCLUSIONS: Sentinel node biopsy with SS and IH more precisely predicted the status of the axilla than routine ALND in this group of patients. SNB will likely replace full axillary dissection in the majority of patients with breast cancer.

Adult↗
PubMed1998

Optimal harvesting policy for single population with periodic coefficients.

In this paper, we examine the exploitation of single population modeled by time-dependent Logistic equation with periodic coefficients. First, it is shown that the time-dependent periodic Logistic equation has a unique positive periodic solution, which is globally asymptotically stable for positive solutions, and we obtain its explicit representation. Further, we choose the maximum annual-sustainable yield as the management objective, and investigate the optimal harvesting policies for constant harvest and periodic harvest. The optimal harvest effort that maximizes the annual-sustainable yield, the corresponding optimal population level, the corresponding harvesting time-spectrum, and the maximum annual-sustainable yield are determined, and their explicit expressions are obtained in terms of the intrinsic growth rate and the carrying capacity of the considered population. Our interesting and brief results generalize the classical results of Clark for a population described by the autonomous logistic equation in renewable resources management.

Conservation of Natural Resources↗
PubMed1998

Comparison of CoMFA models for Salmonella typhimurium TA98, TA100, TA98 + S9 and TA100 + S9 mutagenicity of nitroaromatics.

Comparative Molecular Field Analysis (CoMFA) was applied to a comprehensive data set of heterogeneous nitroaromatics tested in Salmonella typhimurium TA98 and TA100 with and without S9 microsomal activation. The four CoMFA models developed agree with postulated mechanisms of mutagenicity, and explain over 70% of the corresponding mutagenic variance The standard deviation coefficient contours common in the four models included high electronic density regions equivalent to C4-C5 in the pyrene ring, and an electron deficient site equivalent to C6. These areas are associated with high mutagenicity. Electron deficient areas may be related with the nitroreductive bioactivation of nitroaromatics. Electron rich sites may be involved with oxidative mechanisms analogous to the bioactivation pathway of polycyclic aromatic hydrocarbons. The contribution of steric factors to mutagenicity follows the order TA98 + S9 > TA98 > TA100 + S9 > TA100. The models indicated that increasing bulk perpendicular to the aromatic plane would decrease mutagenicity, but increasing the aromatic ring system along a region corresponding to C6-C7 in 1-nitropyrene would increase mutagenicity.

Models, Theoretical↗
PubMed1998

Inhibition of AP-1 and NF-kappaB by manganese-containing superoxide dismutase in human breast cancer cells.

One of the primary antioxidant enzymes, manganese-containing superoxide dismutase (MnSOD), has shown the ability to reverse malignant phenotypes in a variety of human tumor cells that are low or absent in MnSOD expression. We have observed that overexpression of human MnSOD in human breast cancer MCF-7 cells inhibits tumor growth both in vitro and in vivo. The signaling pathway underlying the MnSOD induced tumor suppression is unknown. We demonstrate here that transcriptional and DNA binding ability of AP-1 and NF-kappaB, but not SP-1, were inhibited (by 50%) in the MCF-7 cell line overexpressing MnSOD. When transiently expressing, MnSOD inhibited AP-1 but increased NF-kappaB transactivation, which can be abolished by sodium pyruvate, a hydrogen peroxide scavenger. To analyze the target genes responsible for MnSOD-induced tumor suppression, genes related to tumor growth and responsive to AP-1 or NF-kappaB were analyzed. AP-1 responsive collagenase I, stromelysin I, and NF-kappaB responsive IL-1 and IL-6 were down-regulated in the MnSOD stable transfectants compared to the control cell lines. Since TPA induces differentiation in human breast cancer cells and up-regulates MnSOD gene in HeLa cells, MnSOD expression and AP-1 and NF-kappaB activity were measured under TPA treatment. The results showed that TPA induced endogenous MnSOD expression and inhibited both AP-1 and NF-kappaB. Together, these results suggest that tumor suppression by overexpressing MnSOD is related to a modulation of AP-1 and NF-kappaB, which causes a down-regulation of genes responsible for tumor malignant phenotype.

Breast Neoplasms↗
PubMed1998

Over-expression of c-fos mRNA in the hippocampal neurons in Alzheimer's disease.

OBJECTIVE: To analyze the relationship between the proto-oncogene c-fos change and neuronal degeneration in the hippocampus of the patients with Alzheimer's disease. METHODS: The post mortem human hippocampal tissues were divided into three groups, namely, the aged, the young and Alzheimer's disease (AD) groups. Each group consisted of 10 patients. The diagnosis of AD was made by clinical manifestation and argentatine (Bodían) staining. Patients of both the young and the aged groups had no neurological disorders. The proto-oncogene c-fos mRNA was investigated in the hippocampal neurons using the method of in situ hybridization. RESULTS: The optical density of stained area and the integral within proto-oncogene c-fos mRNA revealed a significant increase in the hippocampal neurons in cases of Alzheimer's disease as compared with the controls. CONCLUSIONS: The over-expression of the proto-oncogene c-fos might play a role in the pathological process of Alzheimer's disease. These changes might result from a suffering stage of the hippocampal neurons or from a compensatory mechanism in the surviving neurons which are not yet affected-by the pathological process.

Adult↗
PubMed1998

Research on nucleolar organizer regions of hippocampal neuron in Alzheimer's disease.

OBJECTIVE: To understand the cellular genetic expression of the cell's population by studying the nucleolar organizer regions (NORs) of hippocampal neuron of Alzheimer's disease (AD). METHODS: The postmortem human hippocampal tissues were divided into three groups, namely, the young, the elderly and the AD groups. Each group contained tissues from 10 patients. The study was conducted using image pattern analysis of the nucleoli-nucleoplasms ratio of the neurons of Nissl's stained pathological cerebral hippocampal tissues, the area of stain, and the integrating absorption of nucleoli of silver-stained NORs. RESULTS: The nucleoli-nucleoplasms ratio of the neurons of Nissl's stained cerebral hippocampal tissues, the area of stain, and the integrating absorption of the nucleoli of hippocampal neuron were decreased in the elderly and the AD groups as compared with the young group. However, the area of stain and the integrating absorption of the nucleoli of the hippocampal neurons were relatively increased in the AD group in comparison with the elderly group. CONCLUSION: Nissl's stain demonstrates the hypofunction of the hippocampal neurons in the elderly and the AD patients. The Silver stain of NORs shows the decline of rDNA transcription activity of the nucleoli of the hippocampal neurons in the elderly and the AD patients. However, the transcription activity of the nucleoli of the hippocampal neurons of AD patients was relatively improved, and the cellular genetic expression of the cell's population was relatively strengthened. These cellular morphological changes have probably reflected the cellular defensive system.

Adult↗
PubMed1998

[Molecular cloning of a novel human lung cancer-associated antigen cDNA].

OBJECTIVE: To clone the gene of human lung cancer-associated antigen. METHODS: The human lung squamous carcinoma cell line L-78 cDNA expression library was constructed with lambda gt 11 Sfi-Not directional cloning vector and screened with the anti-human lung cancer McAb ALT-04. The cDNA clone named hlc-14 was sequenced and further studied. NIH3T3 cells were transfected with the recombinant pXJ41-hlc14 plasmid, and the expression of hlc-14 cDNA was detected and characterized immunohistochemically. Soft agar colony formation assay of the transfectants was performed. RESULTS: A human lung cancer lambda gt 11 cDNA library of 1.4 x 10(6) pfu/ml was constructed. Six cDNA clones were isolated following 4 rounds of immunoscreening. The largest cDNA clone hlc-14 contained 954 bp with no homology to any known gene when screened through GenBank. In the NIH3T3 cells transfectant of hlc-14 cDNA, the expression of the lung cancer-associated antigen was demonstrated. The ability of colony formation of the transfectant in the soft agar was enhanced. CONCLUSION: The hlc-14 clone is a novel human lung cancer-associated antigen cDNA. It provides clues for the study of carcinogenesis mechanism of lung cancer and a novel target gene for the gene therapy of lung cancer.

Amino Acid Sequence↗
PubMed1998

[Cloning and expression of a gene associated with HL60 cell apoptosis induced by inhibition of polyamine biosynthesis].

OBJECTIVE: To clone the gene associated with apoptosis induced by an inhibitor of polyamine biosynthesis, alpha-difluoromethylomithine (DFMO). METHODS: The differential substraction screening was used for gene cloning. The gene expression and apoptosis of transfected HL60 cells were detected by Northern blot, morphological assay, FCM and ladder map of DNA electrophoresis, respectively. RESULTS: An apoptosis-associated gene named dF4 was cloned from HL60 cells treated with polyamine biosynthesis inhibitor. The programmed cell death was demonstrated in the HL60 cells transfected by dF4 gene. CONCLUSION: dF4 gene cloned in this study could be a gene regulating apoptosis of HL60 cells.

Antineoplastic Agents↗
PubMed1998

[The different responses to anoxia in cultured CA1 and DG neurons from newborn rats].

Tissue culture from hippocampal CA1 or dentate gyrus (DG) region was established on the basis of previous neuronal culture technique. The viability, intracellular calcium concentration and brain-derived neurotrophic factor (BDNF) mRNA expression of the two kinds of neurons after anoxia were observed in the counting in the confocal microscopic field and in situ hybridization. It is found that DG neurons are not only more resistant to anoxia, but also have a stronger ability to keep calcium homeostasis and to express BDNF mRNA than CA1 neurons.

Animals↗
PubMed1998

[The experimental study of immunization with purified surface protein antigen I/II from streptococcus mutans in BALB/c mice].

OBJECTIVE: To study the immunogenicity and immunoreactivity of purified surface protein antigen I/II from streptococcus mutans. METHODS: Purified antigen I/II was used to immune BALB/c mice by subcutaneous injection route, and S. mutans whole cells were used as comparison. RESULTS: ELISA showed immunization with antigen I/II highly induced both specific serum IgG antibody and specific salivary IgA antibody against antigen I/II (P < 0.01), but immunization with whole cells only induced specific serum IgG antibody (P < 0.05). CONCLUSION: The study suggest purified antigen I/II is an effective candidate vaccine.

Animals↗
PubMed1998

[The effect of retinoic acid on crown morphogenesis of mouse tooth germs in vitro].

OBJECTIVE: To study the effects of retinoic acid on crown morphogenesis of early tooth germs. METHODS: Mouse tooth organ culture model was used and the functions of different retinoic acid concentration on the first mandibular molar germs of 14-day old mouse embryo were examined. RESULTS: The first mandibular molar germ of 14-day old mouse was at the bud stage. After 6 days culture, tooth germs in culture medium (not containing retinoic acid) developed from bud stage to bell stage and formed normal cusps. The morphogenesis of tooth germs in medium containing 1 x 10(-7) mol/L retinoic acid was similar to molar germs in the medium without retinoic acid. When the concentration of retinoic acid increased to 1 x 10(-6) mol/L, the mouse tooth germs still developed from bud stage to bell stage, but normal cusps was not formed. CONCLUSION: The results suggest that high concentration of retinoic acid alter crown morphogenesis of tooth germs.

Animals↗