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Biomedical subjects

Fan Li

Publications and source records attributed to Fan Li.

At least 37 records · Page 2Linked to original sources
PubMed2005

Use of ramification amplification assay for detection of Escherichia coli O157:H7 and other E. coli Shiga toxin-producing strains.

Escherichia coli O157:H7 and other Shiga toxin-producing E. coli (STEC) strains are important human pathogens that are mainly transmitted through the food chain. These pathogens have a low infectious dose and may cause life-threatening illnesses. However, detection of this microorganism in contaminated food or a patient's stool specimens presents a diagnostic challenge because of the low copy number in the sample. Often, a more sensitive nucleic acid amplification method, such as PCR, is required for rapid detection of this microorganism. Ramification amplification (RAM) is a recently introduced isothermal DNA amplification technique that utilizes a circular probe for target detection and achieves exponential amplification through the mechanism of primer extension, strand displacement, and ramification. In this study, we synthesized a circular probe specific for the Shiga toxin 2 gene (stx(2)). Our results showed that as few as 10 copies of stx(2) could be detected, indicating that the RAM assay was as sensitive as conventional PCR. We further tested 33 isolates of E coli O157:H7, STEC, Shigella dysenteriae, and nonpathogenic E. coli by RAM assay. Results showed that all 27 STEC isolates containing the stx(2) gene were identified by RAM assay, while S. dysenteriae and nonpathogenic E. coli isolates were undetected. The RAM results were 100% in concordance with those of PCR. Because of its simplicity and isothermal amplification, the RAM assay could be a useful method for detecting STEC in food and human specimens.

Animals↗
PubMed2005

Designs in partially controlled studies: messages from a review.

The ability to evaluate effects of factors on outcomes is increasingly important for studies that control some but not all of the factors. Although important advances have been made in methods of analysis for such partially controlled studies, work on designs has been limited. To help understand why, we review the main designs that have been used for such partially controlled studies. Based on the review, we give two complementary reasons that explain the limited work on such designs, and suggest a new direction in this area.

Cluster Analysis↗
PubMed2005

[Cloning of human telomerase reverse transcriptase promoter for targeted cancer therapy].

OBJECTIVE: An human telomerase reverse transcriptase (hTERT) promoter was cloned to investigate the effect of simplex virus-thymidine kinase (HSV-tk) gene-ganciclovir (GCV) system under control of this promoter on lung cancer cells A549. METHODS: Specific primers were designed to amplify the core hTERT promoter from HepG2 genome. A set of expression vectors encoding LacZ or tk gene under control of hTERT or hCMV promoter was constructed through standard molecular cloning methods. After the transfection with lipofectamine 2000, reverse transcriptional PCR (RT-PCR) and beta-Gal staining were performed to examine the activity of the hTERT promoter. The cytotoxic effects of GCV/tk on A549 and MRC5 cells transfected with the plasmids encoding tk gene were evaluated by MTT assay. RESULTS: The hTERT promoter containing -208-+40 bp of the upstream sequence of human telomerase was successfully cloned. beta-Gal staining and RT-PCR were used to detect the expression of Lac Z and the transcription of tk gene under control of the hTERT promoter, respectively, in A549 rather than MRC5 cells. Cyototoxic effect of GCV was observed only in the A549 but not MRC5 cells after the transfection with pDC511 hTERT/tk, and the effect was dose-dependent. The effect, however, was observed in cells transfected with pDC518 hCMV/tk. CONCLUSION: The hTERT promoter cloned in this study can specifically control the target gene expression in telomerase-positive tumor cells but not the normal cells, suggesting that the HSV-tk/GCV system under control of the hTERT promoter is a promising targeted gene therapy for malignant tumors.

Cloning, Molecular↗
PubMed2005

[A clinical study of presurgical nasoalveolar molding in infants with complete cleft lip and palate].

OBJECTIVE: To observe the clinical effect of presurgical nasoalveolar molding in infants with complete cleft lip and palate. METHODS: Presurgical nasoalveolar molding was performed in 38 infants with cleft lip and palate (26 patients with unilateral cleft lip and palate, 12 patients with bilateral cleft lip and palate), aged between 5 and 30 days. The width of alveolar cleft was measured before and after the operation and the effect of treatment was assessed. RESULTS: After 108 - 152 days of therapy, the average width of alveolar cleft decreased by 5.3 mm in 26 patients with unilateral cleft lip and palate. Nasal profile was improved in 76 percent of cases. In 12 patients with bilateral cleft lip and palate, the average width of left cleft decreased by 4.7 mm and that of the right decreased by 4.2 mm. The distance between right and left cleft increased by 5.1 mm. Nasal profile was improved in 66 percent of cases. CONCLUSION: Presurgical nasoalveolar molding in complete cleft lip and palate can improve nasal profile and decrease the width of alveolar cleft.

Alveolar Process↗
PubMed2005

[Mutation of mitochondrial 12S rRNA in gastric carcinomas and its significance].

OBJECTIVE: To detect the alterations of mitochondrial 12S rRNA in patients with gastric cancer, and further evaluate their effects on development of gastric carcinomas. METHODS: Mitochondrial 12S rRNA of 22 samples of gastric cancer tissues and 22 corresponding normal gastric mucosa taken from the distal portion of surgical specimens were PCR amplified, followed by direct DNA sequencing. Laser capture microdissection technique (LCM) was used to isolate cancerous cells and dysplastic cells from patients with specific mutations. Denaturing high-performance liquid chromatography (DHPLC) plus allele-specific PCR (AS-PCR), nest-PCR and polyacrylamide gel electrophoresis (PAGE) were applied to further evaluate this mutant property and quantitative difference of mutant type between cancerous and dysplastic cells. Finally, RNAdraw bio-soft was used to analyze the RNA secondary structure of mutant type 12S rRNA. RESULTS: Compared with mitomap database, some variations were firstly found, among which np652 G insertion and np716 T-G transversion were only found in cancers. There existed statistically significant difference in variant frequency of 12S rRNA between intestinal type and diffuse type of gastric carcinoma, 5/17 (29.4%) and 12/17 (70.6%) respectively (P < 0.05). DHPLC analysis showed that 12S rRNA np652 G insertion and np716 T-G transversion were heteroplasmic mutation. Variant frequency of 12S rRNA in cancer was higher than that in dysplasia (P < 0.01). 12S rRNA 652G insertion had more adverse effect on secondary structure stability of 12S rRNA than T-G transversion did. CONCLUSION: Highly variant frequency of mitochondrial 12S rRNA may be associated with intestinal type of gastric cancer. Most parts of variations exist in both cancer and normal tissues and may not be characteristic of tumor specificity. However np652 G insertion and np716 T-G transversion may possess some molecular significance on gastric cancerogenesis. During the process of progression from normality through dysplasia to cancer, 12S rRNA tended to transit from homoplasmy (wild type) and heteroplasmy to homoplasmy (mutant type, np717 T-G).

Base Sequence↗
PubMed2005

[Presurgical orthodontic treatment of complete unilateral cleft lip and palate in 100 infants].

OBJECTIVE: To investigate the application and curative effect of naso-alveolar molding plate in the presurgical orthodontic treatment of complete unilateral cleft lip and palate in infants. METHODS: From January 2003 to March 2004, 100 infants with complete unilateral cleft lip and palate received presurgical orthopedics by using naso-alveolar molding plate. According to the age, 100 infants (aging 10 days to 3 months, including 60 males and 40 females) were divided into the test group (10 days to 1 month) and the control group (1-3 months). The widths of lip cleft and dentoalveolar cleft and the rate of satisfaction for nose wing were compared between 2 groups before treatment and after the treatment. RESULTS: The widths of cleft lip and dentoalveolar cleft before orthodontic (5.0 +/- 1.6 mm, 6.9 +/- 2.6 mm) and after orthodontics (4.1 +/- 2.7 mm, 6.4 +/- 2.9 mm)in the test group were less than those in the control group (7.5 3.1 mm, 12.5 +/- 4.0 mm and 8.3 +/- 3.0 mm, 10.8 +/- 2.6 mm), being statistically different (P < 0.05). The satisfactory rate of nose wing in the test group (86.3%) was significantly higher than that in the control group (62.4%, P < 0.05). CONCLUSION: The advantages of presurgical orthodontic treatment of complete unilateral cleft lip and palate in infants are as follows: repositioning the premaxillary segment, reducing the width of palate cleft, correcting the nasal deformities and facilitating surgical repair of cleft lip and palate.

Cleft Lip↗
PubMed2005

[Prokaryotic expression, antiserum preparation and cytochemical analysis of TaMlo3 in wheat].

Mlo gene in wheat is critical to determine wheat broad spectrum disease resistance against the pathogenic powdery mildew fungus. According to wheat TaMlo3 cDNA sequence, the two DNA fragments encoding the intracellular loop 2 and C-terminus of wheat Mlo protein were cloned respectively into the vector pET-30a, and then the fusion polypeptides were expressed in E. coli BL21. The recombinant proteins were purified by Ni2+ -NTA agarose column, and then were used to immunize the rabbits respectively. Two polyclonal antisera were obtained and they could be specifically bound on the extrahaustorial membrane and extrahaustorial matrix of the powdery mildew fungus by immuno-gold labeling.

Animals↗
PubMed2004

Dysregulation of insulin receptor substrate 2 in beta cells and brain causes obesity and diabetes.

The molecular link between obesity and beta cell failure that causes diabetes is difficult to establish. Here we show that a conditional knockout of insulin receptor substrate 2 (Irs2) in mouse pancreas beta cells and parts of the brain--including the hypothalamus--increased appetite, lean and fat body mass, linear growth, and insulin resistance that progressed to diabetes. Diabetes resolved when the mice were between 6 and 10 months of age: functional beta cells expressing Irs2 repopulated the pancreas, restoring sufficient beta cell function to compensate for insulin resistance in the obese mice. Thus, Irs2 signaling promotes regeneration of adult beta cells and central control of nutrient homeostasis, which can prevent obesity and diabetes in mice.

Animals↗
PubMed2004

[Quantitation and detection of deletion in tumor mitochondrial DNA by microarray technique].

OBJECTIVE: To develop a method to rapidly quantitate and detect deletion of mitochondrial DNA (mtDNA) by microarray technique as a tool to study its relationship to tumorigenesis. METHODS: A modified PCR was used to amplify full length mtDNA sequence in two samples of normal human blood leukocytes and five samples of gastric cancerous tissues, which were simultaneously labeled with fluorescin. The amplified products were verified by polyacrylamide gel electrophoresis (PAGE) and silver staining. Then, 17 pairs of overlapping primers of mtDNA were designed and their PCR products were used as mitochondrial probes. They were spotted onto amino-slides as microarray and hybridized. Hybridization image was scanned with GeneTAC laser, mtDNA copy number was counted by ScanAnalyzer software. RESULTS: PAGE analysis showed that the designed probes were quite reasonable and strongly specific. The modified PCR method was efficient to amplify the whole mitochondrial genome with high-yield specific bands. The hybridizing spots were distinct, and background was clear. The signals of negative probes were close to those of background, and there was no significant difference between them (P > 0.05). The results were identical to those in the designed experiment. There were no significant differences between the results when the same sample of blood leucocytes or cancer tissues repeatedly examined with the same positive probes (P > 0.05), while there were significant differences when different types of samples were examined (P < 0.01). The hybridizing signals were stable and most of the data distributed in the range of mean +/- 2xSD. CONCLUSION: The method here reported can rapidly, correctly and massively determine whether there exist special deletion and/or quantitative changes of mtDNA in patients with tumors. It will be helpful for the study of the relationship between mtDNA alteration and tumor development.

DNA, Mitochondrial↗
PubMed2004

[Influence of sodium butyrate on growth of HT-29 colon carcinoma cells and expression of inducible nitric oxide synthase (iNOS)].

BACKGROUND & OBJECTIVE: Sodium butyrate could inhibit several cancer cell lines in vitro. This study was designed to investigate the effects of sodium butyrate on the growth of HT-29 colon carcinoma cells, the expression of iNOS, and the excretion of NO. METHODS: The HT-29 cells were co-incubated with sodium butyrate at various concentration. The cell proliferation was determined by MTT test, and the iNOS protein of HT-29 cells was stained by immunochemical SP method. The absorbance value (A value) of iNOS was measured by automatic image analysis system. Griess's technique was used to examine the excretion of nitric oxide (NO). RESULTS: The survival rates of HT-29 cells treated by sodium butyrate decreased in a time-dependent and dose-dependent manner. IC(50) value of sodium butyrate was decreased with prolonged incubation time (15.4 mmol/L at 12 hours, 5.7 mmol/L at 24 hours, 2.5 mmol/L at 36 hours, 0.9 mmol/L at 48 hours). Simultaneously sodium butyrate decreased the expression of iNOS in the cytoplasm and the excretion of NO in a similar manner. CONCLUSION: Sodium butyrate could inhibit the expression of iNOS, consequently reduce the excretion of NO. It may play an important role in the mechanism that sodium butyrate inhibits the growth of HT-29 colon carcinoma cells.

Butyrates↗
PubMed2004

Recovering genetic regulatory networks from micro-array data and location analysis data.

Learning large network (with hundreds of variables) is gaining interest of many researchers with the emergence of high-throughput biological data sources such as micro-array data. In this paper, we investigated the two popular large scale network structure learning algorithms, sparse candidate hill climbing (SCHC) and Grow-Shrinkage(GS) algorithm. The experiments show that in fact both of them have serious effectiveness problems when the number of variables(genes) is large compared to the number of instances(experimental conditions), which is a common case in micro-array data. We further propose a new large scale structure learning algorithm based on Lasso regression. Theoretical analysis in [10] suggested that the L1-norm in lasso regression could make our algorithm especially suitable in the cases that the number of variables and instances is unbalance. Our algorithm achieves much better results than SCHC and GS on the synthetic data. We also show the effectiveness of our algorithm by learning genetic regulatory network modules from a real micro-array data (with more than 6000 genes), combined with the genome-wide location analysis data. The learned results are consistent well with biological knowledge.

Algorithms↗
PubMed2003

The influenza virus gene pool in a poultry market in South central china.

We surveyed influenza activity in a live poultry market in Central China for 16 months, isolating viruses from 1% of 6360 fecal samples. We obtained multiple H3N6, H9N2, H2N9, H3N3, and H4N6 isolates and single H1N1 and H3N2 isolates. Two distinct H3 molecules were identified; other hemagglutinin subtypes were phylogenetically homogeneous. The H3N6 viruses (9 genotypes) and H9N2 viruses (4 genotypes) were genetically heterogeneous, whereas the H2N9, H3N3 and H4N6 viruses had single genotypes. Thirteen representative viruses were tested for their ability to replicate in quail and chickens. All tested viruses replicated in the respiratory tract of quail. Only nine of the viruses were shed in detectable levels in infected chickens, and four of these were detected in less than 50% of infected birds. A single H4N6 isolate caused disease and systemic spread in chickens. These findings show that quail are broadly susceptible to different subtypes of influenza A virus.

Animals↗
PubMed2003

Bone that best matches the properties of the mandible.

OBJECTIVE: The main advantage of primary oromandibular reconstruction using free vascularized bone-containing flaps is improved oral function from (1) the maintenance of mandibular and soft tissue architecture and (2) dental rehabilitation through osseointegrated implants. Bone dimensions, volume, quality, and the ability of the bone to withstand masticatory forces are important factors in achieving successful osseointegration. Previous studies have objectively examined the dimensions of bones used in oromandibular reconstruction, but few have addressed their biomechanical properties. The purpose of this study was to compare the dimensional and biomechanical properties of the bones commonly used in oromandibular reconstruction with those of the mandible. METHODS: Eleven formalin-fixed cadavers were used. The mandibles, fibulae, iliac crests, scapulae, clavicles, second metatarsals, radii, and anterior ribs were harvested. Measurements of the dimensions of the bones were made with calipers at multiple sites. Three-point break strength and screw pulling force tests were then performed on all of the bones. RESULTS: The fibulae, iliac crests, and clavicles had dimensions that best matched those of the mandible. The three-point break strength and screw pulling force tests were consistently the highest for the mandibles and fibulae, followed by the clavicles, scapulae, iliac crests, metatarsals, radii, and ribs, in that order. CONCLUSIONS: The fibula is the bone that best matches the properties of the mandible.

Aged↗
PubMed2003

Variations of mitochondrial D-loop region plus downstream gene 1 2S rRNA-tRNA(phe) and gastric carcinomas.

AIM: To explore the instabilities, polymorphisms and other variations of mitochondrial D-loop region and downstream gene 12S rRNA-tRNA(phe) in gastric cancers, and to study their relationship with gastric cancer. METHODS: Three adjacent regions (D-loop, tRNA(phe) and 12S rRNA) were detected for instabilities, polymorphisms and other variations via PCR amplification followed by direct DNA sequencing in 22 matched gastric cancerous tissues and para-cancerous normal tissues. RESULTS: PolyC or (CA) (n) instabilities were detected in 13/22(59.1 %) gastric cancers and 9/22(40.9 %) in the control (P>0.05). There existed 2/12(16.7 %) and 6/10(60 %) alterations of 12S rRNA-tRNA(phe) in well differentiated gastric cancers and poorly differentiated ones, respectively (P<0.05). Some new variations were found, among which np 318 and np 321 C-T transitions in D-loop region were two of the five bases for H-strand replication primer. np 523 AC-deletion and np 527 C-T transition occurred at mtTF1 binding site (mtTFBS), which were associated with the transcription of downstream mitochondrial genome. Seven samples showed the np 16 182 polyC instabilities, five of which simultaneously showed np 16 189 T-C transitions. CONCLUSION: There is no statistic significance of instabilities and polymorphisms in mitochondrial D-loop region between gastric cancerous and para-cancerous normal tissues, which suggests that the instability might relate to heredity or be dependent on aging. There is a significant correlation between differentiation degree of gastric cancer and variant frequencies of 12S rRNA-tRNA(phe). The poorly differentiated gastric cancers are more prone to 12S rRNA-tRNA(phe) variations, or gastric cancers with 12S rRNA-tRNA(phe) variations are more likely to be poorly differentiated. np 16 189 T-C transition may be one of the important reasons for polyC instability in gastric cancer.

Base Sequence↗
PubMed2003

[Clinical study on fistula incidence of early cleft palate repair].

OBJECTIVE: To study the regularity of fistula incidence after early cleft palate repair METHODS: 531 patients aged 2-12 months at the operation were included in the retrospective study, who underwent cleft palate repair during July 1995 to September 2001. RESULTS: The overall frequency of fistulas was 4.9%. The fistula incidence of bilateral complete cleft palate was obviously higher (7.8%) than that of incomplete cleft palate (4.4%) and the unilateral complete group (4.3%) (P < 0.005). There was no significant difference between the latter two. Fistula incidence was irrelevant to the patient age and the operation method. Seventy percent of fistulas in complete cleft palate occurred on the hard palate, which was significantly higher than that on the other parts. CONCLUSION: Infant cleft palate repair did not increase fistula incidence. We recommend preoperative orthodontics for bilateral cleft palate infants.

Cleft Palate↗
PubMed2002

[Primary biliary cirrhosis: an analysis of 153 cases].

OBJECTIVE: To study the clinical, immunological and pathological features of primary biliary cirrhosis (PBC). METHODS: Clinical and laboratory data of 153 patients with PBC treated in our hospital were retrospectively analyzed. Of these patients, 35 underwent hepatic biopsy. RESULTS: Typical manifestations such as itch of skin and hepatosplenomegaly etc. were found in only 39.2% to 46.4% of the patients and jaundice was seen in 84.3%. The serum level of SB was gradually increased while that of CHE decreased along with progression of PBC (P < 0.01). The level of serum Albumin and ALT was significantly lower in late stage than in the early stages (P < 0.05). ALT and CHE were not correlated with SB. AST level was markedly higher in the late stage than in the early stage (P < 0.05). The levels of ALP and GGT rose at the early stage but remarkably decreased at the middle stage (ALP, P < 0.05) and at the late stage (GGT, P < 0.01). The positive rate of AMA was 83.7% and that of M2 69.3%. As for the 35 patients receiving hepatic biopsy, 10 were AMA positive and the other 25 AMA negative. CONCLUSION: More than half of the patients with PBC do not exhibit typical clinical symptoms and over 80% of the cases of PBC can be diagnosed by investigation of clinical features and detection of AMA and M2. For some cases that can not be definitely diagnosed by observation of clinical features, the final diagnosis should be determined by hepatic biopsy.

Adolescent↗
PubMed2002

[Simultaneous repair of complete cleft lip and palatein infancy-preliminary observation (271 cases report)].

OBJECTIVE: To Verify the safety and reliability of one-stage repair of complete cleft Lip and palate in infancy and to obtain the primary result. METHODS: The simultaneous repair of complete cleft Lip and palate in infants 3 to 12 months of age were performed in 271 cases. The deformities include 185 cases of typical complete unilateral clefts and 75 cases of complete bilateral clefts, and other 11 atypical cleft infants. The preoperative orthopedic treatment for wide alveolar cleft was undertaken in 24 infants and the lip appearance and speech outcome were evaluated in 116 children by 1 to 4 years' postoperative follow-up. RESULTS: All infants, except for dyspnea in 2 babies, palatal fistula formation in 6 cases and temporary wound hemorrhage in 5 infants, were recovered without complications. After orthopedic treatment, the width of the alveolar cleft was reduced 6.1 mm in average. The evaluation showed that 93.1% of children had got good or excellent lip appearance. And the acceptable or excellent speech was found in 94.8% children. CONCLUSIONS: Simultaneous repair of complete cleft lip and palate in infancy is safety and reliable. The preoperative orthopedic procedure is able to reduce the wide alveolar cleft and to achieve alignment of alveolar segments. The acceptable and or excellent lip appearance and speech function could be obtained in this one-stage operative procedure in infants.

Cleft Lip↗