Biomedical subjects

Lin Li

Publications and source records attributed to Lin Li.

At least 163 records · Page 9Linked to original sources

PubMed2004

Identification and characterization of class 1 integron resistance gene cassettes among Salmonella strains isolated from healthy humans in China.

Twenty-three strains of Salmonella spp. isolated from healthy humans in Guangdong, China, were examined for their susceptibility to ten common antibiotics and the presence of antibiotic resistance integrons. All the strains were resistant to at least one antibiotic, and 4 strains were positive for the intI1 gene. Polymerase chain reaction using in-F and in-B primers showed the existence of amplicons of 1,009 bp in two, 1,664 bp in one, and 1,009 bp and 1,664 bp in one of the intI1 -positive isolates, respectively. Sequence analysis revealed that the 1,009-bp amplicon harbored gene cassette aadA2, conferring resistance to spectinomycin, and the 1,664-bp amplicon harbored genes aadA5 and dfr17, conferring resistance to spectinomycin, streptomycin and trimethoprim. Meanwhile the experiments of plasmid conjugation and Southern hybridization with intI1 as the DNA probe indicated that all the integrons found in these strains were chromosomal. Because the strains carrying class 1 integrons were isolated from healthy humans, it suggests the need for all-round surveillance of the antibiotic resistance of pathogens.

Anti-Bacterial Agents↗

PubMed2004

The LRP5 high-bone-mass G171V mutation disrupts LRP5 interaction with Mesd.

The mechanism by which the high-bone-mass (HBM) mutation (G171V) of the Wnt coreceptor LRP5 regulates canonical Wnt signaling was investigated. The mutation was previously shown to reduce DKK1-mediated antagonism, suggesting that the first YWTD repeat domain where G171 is located may be responsible for DKK-mediated antagonism. However, we found that the third YWTD repeat, but not the first repeat domain, is required for DKK1-mediated antagonism. Instead, we found that the G171V mutation disrupted the interaction of LRP5 with Mesd, a chaperone protein for LRP5/6 that is required for transport of the coreceptors to cell surfaces, resulting in fewer LRP5 molecules on the cell surface. Although the reduction in the number of cell surface LRP5 molecules led to a reduction in Wnt signaling in a paracrine paradigm, the mutation did not appear to affect the activity of coexpressed Wnt in an autocrine paradigm. Together with the observation that osteoblast cells produce autocrine canonical Wnt, Wnt7b, and that osteocytes produce paracrine DKK1, we think that the G171V mutation may cause an increase in Wnt activity in osteoblasts by reducing the number of targets for paracrine DKK1 to antagonize without affecting the activity of autocrine Wnt.

Amino Acid Substitution↗

PubMed2004

Gene regulation by Sp1 and Sp3.

The Sp family of transcription factors is united by a particular combination of three conserved Cys2His2 zinc fingers that form the sequence-specific DNA-binding domain. Within the Sp family of transcription factors, Sp1 and Sp3 are ubiquitously expressed in mammalian cells. They can bind and act through GC boxes to regulate gene expression of multiple target genes. Although Sp1 and Sp3 have similar structures and high homology in their DNA binding domains, in vitro and in vivo studies reveal that these transcription factors have strikingly different functions. Sp1 and Sp3 are able to enhance or repress promoter activity. Regulation of the transcriptional activity of Sp1 and Sp3 occurs largely at the post-translational level. In this review, we focus on the roles of Sp1 and Sp3 in the regulation of gene expression.

Animals↗

PubMed2004

Individual subtypes of enteroendocrine cells in the mouse small intestine exhibit unique patterns of inositol 1,4,5-trisphosphate receptor expression.

Enteroendocrine cells are a complex population of intestinal epithelial cells whose hormones play critical roles in regulating gastrointestinal and whole-animal physiology. There are many subpopulations of enteroendocrine cells based on the major hormone(s) produced by individual cells. Intracellular calcium plays a critical role in regulating hormone release. Inositol 1,4,5-trisphophate (IP3) receptors regulate calcium mobilization from endoplasmic reticulum-derived calcium stores in many endocrine and excitatory cells and are expressed in the intestine. However, the specific subtypes of enteroendocrine cells that express these receptors have not been reported. Immunohistochemical (IHC) studies revealed that enteroendocrine cells did not express detectable levels of type 2 IP3 receptors, whereas nearly all enteroendocrine cells that produced chromogranin A and/or serotonin expressed type 1 and type 3 IP3 receptors. Conversely, enteroendocrine cells that produced glucose-dependent insulinotropic polypeptide, glucagon-like peptide-1, cholecystokinin, or somatostatin did not express detectable levels of any IP3 receptors. Subsets of enteroendocrine cells that produced substance P or secretin expressed type 1 (33% or 18%, respectively) and type 3 (10% or 62%, respectively) IP3 receptors. Thus, different subtypes of enteroendocrine cells, as well as individual cells that express a particular hormone, exhibit remarkable heterogeneity in the molecular machineries that regulate hormone release in vivo. These results suggest that therapeutic agents can be developed that could potentially inhibit or promote secretion of hormones from specific subtypes of enteroendocrine cells.

Animals↗

PubMed2004

Factors associated with the initiation and duration of breastfeeding by Chinese mothers in Perth, Western Australia.

To identify determinants of the initiation and duration of breastfeeding by Chinese Australian mothers, a cross-sectional survey of 506 Mandarin-speaking women in Perth, Western Australia, was conducted. Doctors' support of breastfeeding was positively associated with the initiation of breastfeeding both in the mothers' home countries (odds ratio [OR], 9.94; 95% confidence interval [CI], 3.17-31.18) and in Australia (OR, 16.78; 95% CI, 7.12-39.55) and with duration. Mother's level of education was positively associated with the initiation of breastfeeding in the mother's home country (OR, 3.04; 95% CI, 1.36-6.80) and positively associated with the duration of breastfeeding both in the mother's home country and Australia. Father's preference for breastfeeding was positively associated with the initiation of breastfeeding of the mother giving birth in Australia (OR, 4.96; 95% CI, 1.93-12.66). Health professionals can provide invaluable support for mothers initiating and continuing breastfeeding in this population. Prenatal education also needs to emphasize the ways in which fathers can support and contribute to breastfeeding.

Adult↗

PubMed2004

Distribution of T-DNA carrying a Ds element on rice chromosomes.

Over 3000 rice plants with T-DNA carrying a Ds element were constructed by Agrobacterium tumefaciens mediation. Using inverse PCR methodology, 590 unique right flanking sequences of T-DNA (Ds) were retrieved from independent transformants and classified into six main types on the basis of the origin of filler DNA between the right border of T-DNA and flanking sequence of rice genome. Type I sequences were the most common and showed canonical integration that T-DNA right border was followed by rice genome sequence with or without filler DNA of no more than 50 bp, while type II sequences displayed a vector-genome combination that T-DNA right border was followed by a vector fragment and then connected with rice genome sequence. The location and distribution of 340 type I and II flanking sequences on the rice chromosome were determined using BLAST analysis. The 340 Ds insertions at an average interval of 0.8 megabase (Mb) constructed a basic framework of Ds starter points on whole rice chromosomes. The frequency of T-DNA (Ds) inserted into the exons of predicted genes on chromosome one was 21%. Knowledge of T-DNA (Ds) locations on chromosomes will prove to be a useful resource for isolating rice genes by Ds transposon tagging as these Ds insertions can be used as starting lines for further mutagenesis.

Base Sequence↗

PubMed2004

[Effect of ultra-fine powder technique on dissolution rates of andrographolide and dehydroandrographolide in Andrographis paniculata].

OBJECTIVE: To investigate the effects of ultra-fine powder technique on dissolution rates of the components in Andrographis paniculata. METHODS: High performance liquid chromatography was employed to determine the concentration of andrographolide and dehydroandrographolide in common powdered or ultra-fine powdered Andrographis paniculata. RESULTS: The dissolution rates of andrographolide and dehydroandrographolide in ultra-fine powdered Andrographis paniculata were higher than those of the general powder. CONCLUSION: Ultra-fine powder technique promotes the dissolution rates of andrographolide and dehydroandrographolide.

Andrographis↗

PubMed2004

Effect of Maotai liquor on the liver: an experimental study.

BACKGROUND: Epidemiology investigation showed that no worker drunk Maotai liquor for nearly 30 years died of hepatic diseases, and no obvious hepatic fibrosis and cirrhosis were found in 99 workers who had drunk Maotai liquor for a long period by epidemiology investigation and needle biopsy. The same finding was detected in rats that were drunk by Maotai liquor continued for 56 days. This study was to investigate the effects of Maotai liquor on the liver and its mechanism of preventing hepatic fibrosis. METHODS: After ingestion of Maotai for 56 consecutive days, male SD rats were killed for detecting the levels of metallothionein and malondialdehyde (MDA) in liver tissues. Rat hepatic stellate cells (HSCs) and human HSCs were cultured in vitro to observe the effect of Maotai on HSCs proliferation and collagen synthesis. After ingestion of Maotai for 14 consecutive weeks, the livers of male SD rats were harvested for pathohistological examination. RESULTS: The level of metallothionein in the liver of Maotai-induced rats increased by 22 folds, whereas the levels of hepatic lipid peroxide and MDA was decreased significantly (P<0.05) in Maotai-induced animals suffering from CCl4. Maotai demonstrated obvious inhibitory effect on proliferation of HSCs and the inhibition was concentration-dependent. Gene expression and protein secretion of collagens could also be inhibited by Maotai. In alcoholic group, typical liver cirrhosis was observed. In Maotai group, however, though fatty degeneration of hepatocytes and mild fibrosis of the interstitium were observed, no obvious hepatic fibrosis and cirrhosis were found. CONCLUSION: It might be an important mechanism of interfering the progress of hepatic fibrosis that Maotai increases the level of metallothionein in the liver and inhibits the activation of HSCs and the synthesis of collagen proteins.

Alcoholic Beverages↗

PubMed2004

[Change of corneal thickness after laser in situ keratomileusis].

OBJECTIVE: The corneal thickness was measured in and after in situ keratomileusis (LASIK) to investigate the accurate ablation depth on cornea during the operation and the possible mechanism of myopic after operation. METHODS: From August 1999 to June 2000, 650 myopia patients were treated by LASIK. The changes in cornea thickness were measured before, during and 1 week, 1, 3, 6 and 12 month after the surgery. RESULTS: By the measurement of cornea thickness during the operation, the real cornea ablated thickness was (32.15 +/- 7.23) micro m different from the expected value. Central thickness of the cornea and the refraction could be stable in six months after the operation. CONCLUSIONS: The cornea thickness and the refraction would be stable in six months after the operation. Age of the patients is the key factor that influences the stability of ocular refraction.

Age Factors↗

PubMed2004

[Preparation and characterization of monoclonal antibody against N-terminal domain of polycystin 1].

AIM: To prepare and identify monoclonal antibody (mAb) against N-terminal domain of polycystin 1. METHODS: Total RNA was extracted from kidney tissue of a healthy man. Gene sequence encoding polycystin 1 N-terminal domain was amplified by one-step RT-PCR. The target gene was inserted into prokaryotic expression vector pQE30 and transformed into competent cells E. coli M15. The fusion protein was expressed under IPTG induction and purified by affinity chromatography. The purified fusion protein was then used to immunize BALB/c mice. The splenocytes from immunized mice were fused with myeloma cells Sp2/0 by PEG 4000 mediator method and the hybridomas were selected in HAT medium. The hybridoma clones secreting mAb against polycystin 1 amino-terminal domain were detected by ELISA and cloned by limiting dilution. The specificity of mAb against polycystin 1 N-terminal domain was verified by ELISA and Western blot. RESULTS: cDNA encoding polycystin 1 extracellular region was obtained. Fusion protein of polycystin 1 N-terminal domain were expressed in pQE30 expression system. The relative molecular masses (Mr) of the two fusion proteins were 19,800 and 18,900, respectively. One hybridoma cell 7B1 secreting specific mAb was obtained. Western blot analysis showed that the mAb reacted strongly and specifically to polycystin 1 N-terminal domain. CONCLUSION: polycystin 1 N-terminal fusion proteins have been expressed in E.coli M15. Anti-fusion protein mAb with antigen-binding activity has been prepared successfully.

Adult↗

PubMed2004

[Preparation and characterization of anti-morphine antiserum].

OBJECTIVE: To prepare the holoantigens of morphine and morphine-6-succinyl, and to evaluate the efficacy of both of the haptens in eliciting immune responses and their effects on morphine withdrawal symptoms in male mice. METHODS: Morphine-6-succinyl was prepared using acid anhydride mixture, and conjugated, along with morphine, with Blue carrier in the presence of carbodi imide. Immunization of mice with both the holoantigens and Freund adjuvant was performed, followed by determination of the antibody titer in the mouse serum with competitive ELISA and morphine dependence evaluation. RESULTS: The titers of the antibodies exceeded 1:8 000 in the serum of mice immunized with both holoantigens, and morphine- 6-succinyl induced a higher titer that was maintained for a longer period. The inhibition rates of the antisera to morphine and morphine-6-auccinyl had both reached 50%, and increased in a dose-dependent manner. CONCLUSION: Both morphine carrier conjugates can elicit high-titer antibody response in mice and relieve morphine addiction.

Animals↗

PubMed2004

[Study on odors treatment by the combination of bacteria and fungi].

The aim of this study was to establish a novel combined-bioreactor for the treatment of odors. The combined-bioreactor consists of two zones, one bacteria zone and one fungi zone. An experiment for the odor treatment was carried out, and the removal efficiency of acetic acid, ammonia, styrene, hydrogen sulfide, ethyl mercaptan and diethylsulfide which were main material in this experimental odor were 97.1%, 96.7%, 96.6%, 92.1%, 78% and 83%, respectively. The experimental results clearly showed that bacteria and fungi in the combined-bioreactor had a synergistic reaction, therefore, the hydrophilic and hydrophobic compounds can be efficiently removed in this combined-bioreactor. The monitor results indicated that the removals of the compounds with varying water solubility were different in the two zones of the bioreactor.

Bacteria↗

PubMed2004

[Effects of Yizhi capsule, a preparation of traditional Chinese medicines, on delayed neuronal death in hippocampal CA1 region and memory function of rats after ischemia-reperfusion injury].

OBJECTIVE: To observe the effects of Yizhi capsule, a preparation of traditional Chinese drugs on delayed neuronal death in the hippocampal CA1 region and memory function of rats after ischemia-reperfusion injury. METHODS: Rat models of acute reperfusion injury after global cerebral ischemia were induced by vertebral and carotid arteries occlusion, and 1, 2, 4, 8 and 40 d after model establishment, the neurons in the rat hippocampal CA1 region were obtained and immunohistochemically stained for counting. Morris water maze test was performed to observe the learning and memory capacities of the rats 40 d after the injury. RESULTS: The number of normal neurons was significantly higher in the rats treated with Yizhi capsule (100 mg/kg.b.w.) than in those without the treatment, and the former group of rats used significantly shorter time in finding the platform under the water surface in Morris water maze test. CONCLUSION: Yizhi capsule may protect the neurons in the hippocampal CA1 region and improve on the learning and memory dysfunction after global ischemia/reperfusion injury in rats.

Animals↗

PubMed2004

[Pathological study of the therapeutic effect of wen-yang herbs on experimental liver cirrhosis].

OBJECTIVE: To observe the pathological effect of wen-yang herbs on experimental hepatic fibrosis. METHODS: Thirty-two male Wistar rats were used in this study comprising four groups. To start with, 24 rats of three groups were given subcutaneous injection of CCl4 and drinking 10% alcohol so as to make the model of hepatic fibrosis. After the establishment of the pathologic model, the rats were divided into the model group, the pathological control group and the therapeutic group by randomization. The rats of the therapeutic group were given the herbal remedies via gastrogavage, q.d. x 30. The rats of the pathological control group were given normal saline via gastrogavage, q.d. x 30. Then liver tissue Hydroxyproline (Hyp) content was examined in these 3 groups and the normal group. Quantitative marks were done according to a modified semiquantitative scoring system (SSS). The results of SSS marks and Hyp contents were analysed using Pearson's coefficient of correlation. RESULTS: The Hyp content and SSS marks of the therapeutic group decreased remarkably as compared with those of the control group (P<0.01), and the SSS marks had a strong positive correlation with Hyp content (r=0.804). CONCLUSION: Wen-yang herbs can mitigate the rats' hepatic fibrosis and promote a recovery of their experimental illness.

Animals↗

PubMed2004

Procyanidins from grape seeds protect against phorbol ester-induced oxidative cellular and genotoxic damage.

AIM: To evaluate the inhibitory effects of Vitis vinifera procyanidins (PAs) on carcinogen-induced oxidative stress. METHODS: The single cell gel electrophoresis technique (comet assay) was employed to detect DNA damage induced by the carcinogen phorbol-12-myristate-13-acetate (PMA). The release of hydrogen peroxidase from polymorphonuclear leukocytes (PMNs) was assayed by the horseradish peroxidase-mediated oxidation of phenol red. The microplate assay was used to detect the presence of oxidative products by means of 2',7'-dichlorofluorescin-diacetate (DCFH-DA). The superoxide dismutase (SOD) activity of liver mitochondria was assayed, based on the ability of SOD to inhibit the generation of superoxidate anions by the xanthine-xanthine oxidase system. The malondialdehyde (MDA) level was determined by the thiobarbituric acid (TBA) assay. RESULTS: DNA of NIH3T3 cells was significantly damaged after addition of PMA. The length of the comet tail was observed,while in normal cells the comet tail could not be observed. PAs showed significant protective effects on carcinogen PMA-induced DNA damage. Through assessment of DCFH-DA oxidation, PAs were shown to inhibit the PMA-induced release of hydrogen peroxide by PMNs, and to inhibit respiratory burst activity in NIH3T3 mouse fibroblasts. Ex vivo study showed that serum from rats administered with PAs displayed similar effects in a dose-dependent manner. In addition, PAs suppressed liver mitochondrial lipid peroxidation induced by PMA. PAs protected the activity of SOD and decreased the level of MDA in liver mitochondria damaged by PMA. CONCLUSION: Dietary PAs from grape seeds protect against carcinogen-induced oxidative cellular and genotoxic damage.

Animals↗

PubMed2004

[Inhibition of river clam extract LX01 on human lung epithelial carcinoma cell line A549].

OBJECTIVE: To explore the inhibition effect of river clam extract LX01 on human lung epithelial carcinoma (A549) in mice. METHODS: The inhibition ratio of LX01 on A549 was detected by MTT method. A549 was inoculated into BALB/c mice, and 2 days later, LX01 (50, 100, 200 mg/kg.d) or cytoxan (0.02 mg/kg.d) were administrated for 15 days. Tumor weight, survival time and leukocyte count were measured. RESULTS: Tumor growth was markedly inhibited by LX01 in a dose- dependent manner. LX01 could significantly extend the survival time compared with the control group (P<0.01), but LX01 did not reduce leukocyte count of mice transplanted with A549. CONCLUSION: LX01 could efficiently inhibit the growth of A549 transplanted into mice and maintain the normal immunological function.

Adenocarcinoma↗

PubMed2004

[Potential effect of tumor necrosis factor-alpha and its receptor II gene polymorphisms on the pathogenesis of coal worker's pneumoconiosis].

OBJECTIVE: To approach the effect of tumor necrosis factor-alpha (TNF-alpha) and tumor necrosis factor receptor II (TNFRII) gene polymorphisms on genetic susceptibility of coal worker's pneumoconiosis and their relationship with pulmonary fibrosis. METHODS: Two hundred and thirty-four cases of coal worker's pneumoconiosis (CWP) and four hundred and forty coal mine workers (controls) were selected, and the cases of CWP were divided into three subgroups based on the various stages of I, II and III. 3 ml peripheral vein blood was drawn from every subject. Using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) techniques, TNF-alpha and TNFRII gene polymorphisms were analyzed. RESULTS: In both group matching and 1:1 paired matching, there was no significant difference between CWP workers and controls in distribution frequencies of G/A + A/A (TNF-alpha -308) and T/G + G/G (TNFRII 196) genotypes. The distribution frequency of G/A + A/A genotype in CWP with stage III (20.00%) was higher than those in control (10.91%), and CWP cases with stage I (10.34%) and II (7.50%) respectively. The risk of CWP with stage III in those with G/A + A/A genotype was 2-fold higher than with G/G genotype (OR = 3.00, 95% CI: 0.35 approximately 25.84) for 1:1 paired matching. CONCLUSIONS: TNF-alpha and TNFRII gene polymorphisms does not play an important role in susceptibility to CWP of Han race. TNF-alpha gene promoter polymorphisms might be related with the degree of severe pulmonary fibrosis in CWP.

Aged↗

PubMed2004

[Correlation between local hormones and CD36 transcription level in women with polycystic ovary].

OBJECTIVE: To detect CD(36) expressions in polycystic ovary (PCO), and to explore its correlation with local androgen and insulin at transcription level. METHODS: From August 2002 to February 2003, 12 patients with asymmetric PCO, 15 primary or secondary infertile patients without endocrine disorders and 8 polycystic ovary syndrome (PCOS) with bilateral PCO were recruited. Extraction of follicular fluid and detection of testosterone (T), dehydroepiandrosterone sulfate (DHEAS), insulin (INS) and androstenedione (A(2)) were performed. Relative CD(36) mRNA expression level of human ovarian inner thecal cells was analyzed by auto image analysis system (IAS) after RT-PCR. RESULTS: The level of CD(36) mRNA expression in thecal cells was 0.24 +/- 0.07 in polycystic ovary of PCO group and 0.21 +/- 0.05 in bilateral ovaries of PCOS group, respectively, which were significantly lower than 0.83 +/- 0.13 in normal ovaries (P < 0.01). T and INS levels of follicle fluid in PCO were significantly higher than that in normal ovaries (P < 0.01). T and INS levels of follicle fluid were negatively related to CD(36) mRNA expression of follicular theca interna (r = -0.6810, r = -0.6708, P < 0.01). CONCLUSION: Decrease of scavenger receptor gene CD(36) mRNA may play a role in the pathogenesis of PCO by increasing the level of T and INS in follicular fluid.

Adult↗