PubMed Health⌕ Search

Biomedical subjects

M Fan

Publications and source records attributed to M Fan.

At least 55 records · Page 3Linked to original sources
PubMed2000

[Differentiation of achondroplasia and other similar genetic dwarfism by FGFR3 gene analysis].

OBJECTIVE: To study the gene mutation of Chinese patients with achondroplasia(ACH) and to set up a simple and rapid molecular diagnostic method to differentiate ACH from other similar genetic dwarfism. METHODS: The specific fragment of fibroblast growth factor receptor 3(FGFR3) transmembrane domain was amplified from dried blood spots of 21 patients with ACH and 6 suspicious patients with ACH by polymerase chain reaction, then mutation was screened and detected by restrictive enzyme analysis, single strand conformation polymorphism(SSCP) and denaturing gradient gel electrophoresis(DGGE). RESULTS: One out of 6 suspicious cases was ACH and 5 were pseudoachondroplasia(PSACH). Twenty-one out of 22 patients with ACH bore a G to A transition at nucleotide 1138 and 1 bore a G to C transversion at this same position. CONCLUSION: The nucleotide 1138 of FGFR3 gene is also the hotspot of mutation in Chinese patients with ACH. A simple and rapid molecular diagnostic method has been set up to differentiate ACH from other similar genetic dwarfism.

Achondroplasia↗
PubMed2000

[Identification of quantitative trait loci associated with fruit traits in watermelon [Citullus lanantus (Thanb) Mansf] and analysis of their genetic effects].

In this study, we mapped and characterized quantitative trait loci (QTL) affecting watermelon fruit traits. A total of 118 F2 progenies derived from the cross 97103 (which is a cultivar with higher total soluble solids concentration, thin rind, susceptible to Fusarium wilt disease) x PI296341(which is a wild germplasm with lower total soluble solids concentration, thick rind, resistant to Fusarium wilt disease) were used to construct a 96-markers map in watermelon. By using interval mapping 4 QTLs for total soluble solids concentration, 5 QTLs for hardness of rind, 2 QTLs for thickness of rind, 3 QTLs for weight of simple fruit, and 6 QTLs for weight of one thousand grain seeds were identified. In addition, the explained variations, additive effects and dominance effects for all detected QTLs were analyzed.

Chromosome Mapping↗
PubMed2000

[Effects of hypoxic preconditioning on anoxic tolerance and IL-1 beta expression in cultured rat hippocampal neurons].

AIM: To study the effects of hypoxic-preconditioning on anoxia-tolerance and IL-1 beta expression in cultured rat hippocampal neurons after anoxia. METHODS: 12 day cultured hippocampal neurons in control and hypoxic-preconditioning group were exposed to anoxic environment(0.9 L/LN2 + 0.1 L/LCO2) for 2, 4, 8 and 12 h. The neurons were immunocytochemically stained using the anti-serum against rhIL-1 beta, The number of survival neurons and the mean optical density (OD) of IL-1 beta expression were investigated. RESULTS: The morphological changes and IL-1 beta expression induced by acute anoxia in hypoxic-preconditioning neurons were significantly less than those in control. The number of survival neurons was higher in the hypoxia-preconditioning group than that in control group after acute hypoxia. CONCLUSION: Hypoxia-preconditioning can induce the development of anoxia-tolerance in cultured hippocampal neurons. The decreased IL-1 beta in hippocampal neurons may be an adaptive reaction to acute anoxia.

Animals↗
PubMed2000

In situ hybridization analysis of transforming growth factor-beta 1 RNA expression during mouse tooth development.

OBJECTIVE: The aim of this study is to investigate the temporal and spatial expression and localization of transforming growth factor-beta 1 mRNA during mouse tooth development. METHODS: The distribution pattern of TGF-beta 1 mRNA during tooth development was analyzed on 5 microns serial sections of paraformaldehyde-fixed and paraffin-embedded embryonic mouse heads or mandibles. RESULTS: The results show that TGF-beta 1 mRNA is expressed during mouse tooth development in a temporally and spatially regulated fashion. Local expression of TGF-beta 1 mRNA in the dental epithelium at budstaged (E13) and capstaged (E15) teeth were observed. During bell stage (E16-18), TGF beta 1 mRNA was very abundant in the ameloblast layer and dental papilla cells. The expression of TGF-beta 1 increased in the layer of odontoblast and ameloblast with the differentiation of these cells. CONCLUSION: These results suggest that TGF-beta 1 may have an important role in odontogenesis and that it acts as a paracrine and autoinducing factor.

Ameloblasts↗
PubMed2000

Immunohistochemistry of bone sialoprotein and osteopontin during reparative dentinogenesis in vivo.

OBJECTIVE: To investigate the stage-specific and tissue expression of bone sialoprotein (BSP) and osteopontin (OPN) during reparative dentinogenesis in vivo. METHODS: Direct pulp-capping with Ca(OH)2 developed a model used for the investigation of reparative dentinogenesis in the exposed dental pulp. In this model, standardized class V cavities were prepared close to the gingival margin on the buccal surface of each tooth. Animals were sacrificed 3, 7, and 10 days post-operation. Immunohistochemical staining determined the tissue-specific expression of BSP and OPN during the process. RESULTS: Odontoblast-like cells and reparative dentin reacted positively with BSP and OPN. The expression of BSP reached a peak at day 7, then gradually decreased, while the expression of OPN showed no significant difference between day 7 and day 10. CONCLUSION: BSP and OPN may play different roles in reparative dentinogenesis. BSP may serve as a nucleator of hydroxyapatite crystal formation.

Animals↗
PubMed2000

Immunolocalization of heat shock protein 70 during reparative dentinogenesis.

OBJECTIVE: To investigate the immunolocalization of heat shock protein 70 (hsp 70) during reparative formation and to discuss the role of heat shock response in dental pulp injury and repair. METHODS: A single cavity was prepared in the mesial surface of the first molars of both maxilla and mandible in Wistar rat. The animals were sacrificed at 3, 15, and 30 days post-operation. After the histological process, the paraffin sections were reacted with monoclonal antibodies against rat hsp 70 using the strept-avidin-biotin-peroxidase complex method. RESULTS: Immunolocalization demonstrated heavy staining for hsp 70 in normal pulp and at different stages of dental pulp repair. In normal pulp, immunoreactivity was visualized in the odontoblasts and the pulp fibroblast. In the group sacrificed at 3 days, heavy staining was located in the odontoblast process and cytoplasm. After 15 days, the newly formed odontoblast-like cells were strongly stained. At 30 days, the same staining intensity was observed in odontoblast-like cells and in pulp cells. No staining was seen in reparative dentin. CONCLUSION: These results demonstrated that heat shock protein 70 might play an important role as a molecular chaperone during reparative dentin formation.

Animals↗
PubMed2000

[Difluoromethylornithine synergizes with antisense bcl-2 RNA in the induction of apoptosis of HL60 cells].

OBJECTIVE: To study the combined effect of difluoromethylornithine (DFMO) and bcl-2 antisense RNA in the induction of apoptosis of HL60 cells. METHODS: HL60 cells were transfected with recombinant retroviral vector expressing bcl-2 antisense RNA. The growth characteristics of transfectants were studied by morphological observation, growth curve, FCM analysis, colony formation in soft agar, DNA electrophoresis, molecular hybridization and immunocytochemical staining. RESULTS: The recombinant retroviral vectors expressing bcl-2 antisense RNA and the cell line producing recombinant virus were constructed. Although the expression of bcl-2 at mRNA and protein levels in the HL60 cells transfected with antisense bcl-2 were down-regulated, there was no change in cell growth, cell cycles and expression of ornithine decarboxylase (ODC) compared with the parental cells albeit some decrease in colony formation. In addition, transfection with antisense bcl-2 did not induce marked apoptosis whereas treatment of the transfectant with low concentration (0.2 mmol/L) of DFMO resulted in enhanced expression inhibition of bcl-2 protein, inhibition of cell growth and induction of apoptosis. CONCLUSION: DFMO synergizes with antiense bcl-2 RNA in the induction of apoptosis of HL60 cells.

Antineoplastic Agents↗
PubMed2000

[Periodontal regeneration by application of the porous beta-TCP/BMP artificial bone to Class II furcation defects].

OBJECTIVE: To study the regeneration of periodontal tissue after the application of beta-TCP/BMP artificial bone to class II furcation defects. METHODS: Periodontal defects were produced surgically around premolar teeth in 4 dogs. The flap surgery was performed and the root surfaces were curetted to remove the periodontal ligament and the cementum. A synthetic bioabsorble barrier manufactured from poly DL-lactide was used. The defects were divided into 3 groups (beta-TCP/BMP + PDLLA, PDLLA, control). 12 weeks after surgery, the animals were sacrificed and the teeth with their supporting periodontium were processed for light microscopic evaluation. RESULTS: The definitive evidences of regeneration were founded both in BMP/GTR group and GTR group, but the BMP/GTR group exhibited more new bone formation, cementum deposition occupying the majority of the furcation defects than the other two groups. CONCLUSION: It was concluded that the beta-TCP/BMP artificial bone can be used in GTR technique to promote periodontal regeneration.

Animals↗
PubMed2000

[The effect of immune bovine whey on cell-associated glucosyltransferase activity of Streptococcus mutans].

OBJECTIVE: To study the effect of immune bovine whey on cell-associated glucosyltransferase (GTF) activity of S. mutans MT8148. METHODS: The immune milk was collected from cows immunized with cell-associated GTF overexpression strain B-29-33 of S. mutans MT8148. The control milk was from non-immunized cows. The immune absorbed whey was gotten from immune bovine whey which was absorbed with lyophilized Formalin-killed B-29 whole cells. Three kinds of whey were subdivided into three groups: 50 microliters, 70 microliters, 90 microliters. The content of insoluble glucan was estimated colorimetrically by anthrone method. RESULTS: The control bovine whey had an enhancing GTF activity (407.00%-485.62%). The immune absorbed whey inhibited partly the enhancing GTF activity (208.74%-273.00%). The immune whey inhibited significantly the GTF activity (70.24%-38.62%) and the inhibition showed a tendency to depend on doses. CONCLUSIONS: The immune bovine whey inhibits significantly the cell-associated GTF activity of S. mutans MT8148.

Animals↗
PubMed2000

[Tissue engineered neo-cartilage using polymer substrates and chondrocytes: experimental study].

OBJECTIVE: To investigate the possibility of using poly beta-hydroxybutyrate (PHB) as a scaffold for chondrocytes and the feasibility of generating tissue engineered cartilage in rabbit animal model. METHODS: The articular cartilage from 4-week-old rabbits was enzymatically dissolved by type II collagenase, and chondrocytes were harvested and seeded into foams of PHB. After incubation for 1 week in vitro, chondrocyte-polymer constructs were implanted subcutaneously into rabbits. Two respective control groups were established by subcutaneous implantation of PHB foams and chondrocytes alone. The rabbits were killed at 4, 8, 12 weeks postoperatively, and the specimens were dissected and examined macroscopically, histologically and immunohistochemically. RESULTS: Specimens harvested from chondrocyte-polymer constructs and subjected to gross morphologic and histologic analysis demonstrated new cartilage formation, and those from control groups showed no cartilage formation. CONCLUSION: These findings demonstrate that the foam of PHB is not only a good "matrix" for cartilage tissue engineering, but also optimal scalffold for the seeding of chondrocytes to generate new cartilage that would be useful in plastic and reconstructive surgery.

Animals↗
PubMed2000

[Responses induced by dopamine in Xenopus laevis oocytes injected with mRNA from heat injured rat striatum].

Poly(A)(+) mRNA isolated from the striatum of normal rats and heat injured rats by RNAgents Total RNA Isolation System and PolyTract mRNA RNAgents Isolation Systems was microinjected into Xenopus laevis oocytes to express functional neurotransmitter receptors. Membrane currents were recorded by the conventional patch clamp technique for measuring the relative amounts of mRNA encoding dopamine receptor in order to study the change in dopamine receptors in heat injured rat striatum. There was no change in resting membrane potentials of the oocytes before and after mRNA injection. Dopamine induced membrane currents were shown to be mediated through Cl( ). The oocytes injected with mRNA from heat injured rat striatum were less sensitive to dopamine than those injected with mRNA from normal rats ( P<0.05). The above result showed that heat injury affected gene expression and signal transduction of dopamine receptors in rat striatum.

Animals↗
PubMed1999

Activation of PPARgamma coactivator-1 through transcription factor docking.

Transcriptional coactivators have been viewed as constitutively active components, using transcription factors mainly to localize their functions. Here, it is shown that PPARgamma coactivator-1 (PGC-1) promotes transcription through the assembly of a complex that includes the histone acetyltransferases steroid receptor coactivator-1 (SRC-1) and CREB binding protein (CBP)/p300. PGC-1 has a low inherent transcriptional activity when it is not bound to a transcription factor. The docking of PGC-1 to peroxisome proliferator-activated receptor gamma (PPARgamma) stimulates an apparent conformational change in PGC-1 that permits binding of SRC-1 and CBP/p300, resulting in a large increase in transcriptional activity. Thus, transcription factor docking switches on the activity of a coactivator protein.

Animals↗
PubMed1999

Occult metastases in the sentinel lymph nodes of patients with early stage breast carcinoma: A preliminary study.

BACKGROUND: Thirty percent of lymph node negative patients with operable breast carcinoma experience disease recurrence within 10 years. Retrospective serial sectioning of axillary lymph nodes has revealed undetected metastases in 9-30% of these patients. These occult metastases have been shown to have an adverse effect on survival. Serial sectioning (SS) is impractical for all axillary lymph nodes harvested from Levels I and II, but it is feasible if applied only to sentinel lymph nodes. METHODS: Sentinel lymph nodes from 52 patients with invasive breast carcinoma were cut at 2 mm intervals, fixed in 10% formalin, and embedded in paraffin. Sections were taken from the blocks, stained with hematoxylin and eosin (H & E), and compared with cytokeratin-stained sections taken at 0.25 mm intervals throughout the entire blocks. RESULTS: Tumor metastases were found in 6 patients (12%) when the sentinel lymph nodes were sectioned at 2 mm intervals and stained with H & E, compared with 30 patients (58%) when the same lymph nodes were serially sectioned at 0.25 mm intervals and stained with cytokeratin. Of 24 patients whose metastases were detected by SS and cytokeratin staining, 12 had isolated tumor cells and 12 had colonies of several thousand malignant cells. CONCLUSIONS: Routine histologic examination of axillary lymph nodes, including sentinel lymph nodes, in cases of breast carcinoma significantly underestimates lymph node metastases. This deficiency may be overcome by SS of the entire lymph nodes and staining with a specific monoclonal antibody. The percentage of patients found to have colonies of cells that were missed by routine sectioning corresponds closely to the percentage of "lymph node negative" patients who would be expected to relapse. The true clinical significance of these occult metastases will be determined by long term follow-up. [See editorial on pages 905-7, this issue.]

Adult↗
PubMed1999

The effect of patient-specific factors on radiation-induced regional lung injury.

PURPOSE: To assess the impact of patient-specific factors on radiation (RT)-induced reductions in regional lung perfusion. METHODS: Fifty patients (32 lung carcinoma, 7 Hodgkin's disease, 9 breast carcinoma and 2 other thoracic tumors) had pre-RT and > or = 24-week post-RT single photon emission computed tomography (SPECT) perfusion images to assess the dose dependence of RT-induced reductions in regional lung perfusion. The SPECT data were analyzed using a normalized and non-normalized approach. Furthermore, two different mathematical methods were used to assess the impact of patient-specific factors on the dose-response curve (DRC). First, DRCs for different patient subgroups were generated and compared. Second, in a more formal statistical approach, individual DRCs for regional lung injury for each patient were fit to a linear-quadratic model (reduction = coefficient 1 x dose + coefficient 2 x dose2). Multiple patient-specific factors including tobacco history, pre-RT diffusion capacity to carbon monoxide (DLCO), transforming growth factor-beta (TGF-beta), chemotherapy exposure, disease type, and mean lung dose were explored in a multivariate analysis to assess their impact on the coefficients. RESULTS: None of the variables tested had a consistent impact on the radiation sensitivity of regional lung (i.e., the slope of the DRC). In the formal statistical analysis, there was a suggestion of a slight increase in radiation sensitivity in the dose range >40 Gy for nonsmokers (vs. smokers) and in those receiving chemotherapy (vs. no chemotherapy). However, this finding was very dependent on the specific statistical and normalization method used. CONCLUSION: Patient-specific factors do not have a dramatic effect on RT-induced reduction in regional lung perfusion. Additional studies are underway to better clarify this issue. We continue to postulate that patient-specific factors will impact on how the summation of regional injury translates into whole organ injury. Refinements in our methods to generate and compare SPECT scans are needed.

Adult↗
PubMed1999

Existence and global attractivity of positive periodic solutions of periodic n-species Lotka-Volterra competition systems with several deviating arguments.

In this paper, we study the existence and global attractivity of positive periodic solutions of periodic n-species Lotka-Volterra competition systems. By using the method of coincidence degree and Lyapunov functional, a set of easily verifiable sufficient conditions are derived for the existence of at least one strictly positive (componentwise) periodic solution of periodic n-species Lotka-Volterra competition systems with several deviating arguments and the existence of a unique globally asymptotically stable periodic solution with strictly positive components of periodic n-species Lotka-Volterra competition system with several delays. Some new results are obtained. As an application, we also examine some special cases of the system we considered, which have been studied extensively in the literature. Some known results are improved and generalized.

Animals↗
PubMed1999

Molecular and idiotypic analyses of the antibody response to Cryptococcus neoformans glucuronoxylomannan-protein conjugate vaccine in autoimmune and nonautoimmune mice.

The antibody response to Cryptococcus neoformans capsular glucuronoxylomannan (GXM) in BALB/c mice frequently expresses the 2H1 idiotype (Id) and is restricted in variable gene usage. This study examined the immunogenicity of GXM-protein conjugates, V (variable)-region usage, and 2H1 Id expression in seven mouse strains: BALB/c, C57BL/6, A/J, C3H, NZB, NZW, and (NZB x NZW)F(1) (NZB/W). All mouse strains responded to vaccination with GXM conjugated to tetanus toxoid (TT), the relative magnitude of the antibody response being BALB/c approximately C3H > C57BL/6 approximately NZB approximately NZW approximately NZB/W > A/J. Analysis of serum antibody responses to GXM with polyclonal and monoclonal antibodies to the 2H1 Id revealed significant inter- and intrastrain differences in idiotype expression. Thirteen monoclonal antibodies (MAbs) (two immunoglobulin M [IgM], three IgG3, one IgG1, three IgG2a, two IgG2b, and two IgA) to GXM were generated from one NZB/W mouse and one C3H/He mouse. The MAbs from the NZB/W mouse were all 2H1 Id positive (Id(+)) and structurally similar to those previously generated in BALB/c mice, including the usage of a V(H) from the 7183 family and Vkappa5.1. Administration of both 2H1 Id(+) and Id(-) MAbs from NZB/W and C3H/H3 mice prolonged survival in a mouse model of cryptococcosis. Our results demonstrate (i) that V-region restriction as indicated by the 2H1 Id is a feature of both primary and secondary responses of several mouse strains; and (ii) that there is conservation of V-region usage and length of the third complementarity-determining region in antibodies from three mouse strains. The results suggest that V-region restriction is a result of antibody structural requirements necessary for binding an immunodominant antigen in GXM.

Animals↗
PubMed1999

Effects of monoclonal antibody on colonization of Streptococcus sobrinus and development of dental caries in rats.

OBJECTIVE: To investigate the effect of local application of monoclonal antibody (McAb) raised against the 210KD cell surface protein antigen (PAg) of Streptococcus sobrinus on the colonization of rats' teeth and the development of dental caries. MATERIALS AND METHODS: Thirty Wistar rats were divided into 3 groups: group 1 received McAb against PAg; group 2 received unrelated mice ascites; group 3 received pure buffered saline. The bacteria were applied 6 times to the occlusal surfaces of molars and to the labial surfaces of incisors. After three applications, streptomycin-resistant S. sobrinus 6715 was applied to the teeth and the rats were fed with caries-inducing diet 2000. The number of colonized S. sobrinus was counted on the streptomycin-supplemented mutans streptocci agar and expressed as a percentage of the total colonies on BHI agar. The presence of caries was examined and scored following Keyes' procedure. RESULTS: There were significantly lower levels of colonization by S. sobrinus on rats' teeth and lower mean caries scores on the teeth treated with McAb compared with those in the control groups. CONCLUSION: Local passive immunization with McAb against PAg may be an effective way to prevent colonization by implanted S. sobrinus and development of dental caries.

Analysis of Variance↗