Search PubMed⌕ Search

Biomedical subjects

G Sun

Publications and source records attributed to G Sun.

At least 91 records · Page 5Linked to original sources
PubMed2000

NPC1-containing compartment of human granulosa-lutein cells: a role in the intracellular trafficking of cholesterol supporting steroidogenesis.

Steroidogenic cells represent unique systems for the exploration of intracellular cholesterol trafficking. We employed cytochemical and biochemical methods to explore the expression, regulation, and function of the Niemann-Pick C1 protein (NPC1) in human granulosa-lutein cells. NPC1 was localized in a subset of lysosome-associated membrane glycoprotein 2 (LAMP-2)-positive vesicles. By analyzing the sensitivity of NPC1 N-linked oligosaccharide chains to glycosidases and neuraminidase, evidence was obtained for movement of nascent NPC1 from the endoplasmic reticulum through the medial and trans compartments of the Golgi apparatus prior to its appearance in cytoplasmic vesicles. NPC1 protein content and the morphology and cellular distribution of NPC1-containing vesicles were not affected by treatment of the granulosa-lutein cells with 8-Br-cAMP, which stimulates cholesterol metabolism into progesterone. In contrast, steroidogenic acute regulatory (StAR) protein levels were increased by 8-Br-cAMP. Incubation of granulosa-lutein cells with low-density lipoprotein (LDL) in the presence of the hydrophobic amine, U18666A, caused accumulation of free cholesterol in granules, identified by filipin staining, that contained LAMP-2 and NPC1. These granules also stained for neutral lipid with Nile red, reflecting accumulation of LDL-derived cholesterol esters. LDL-stimulated progesterone synthesis was completely blocked by U18666A, leaving steroid output at levels similar to those of cells incubated in the absence of LDL. The hydrophobic amine also blocked the LDL augmentation of 8-Br-cAMP-stimulated progesterone synthesis, reducing steroid production to levels seen in cells stimulated with 8-Br-cAMP in the absence of LDL. Steroidogenesis recovered after U18666A was removed from the culture medium. U18666A treatment caused a 2-fold or more increase in NPC1 protein and mRNA levels, suggesting that disruption of NPC1's function activates a compensatory mechanism resulting in increased NPC1 synthesis. We conclude that the NPC1 compartment plays an important role in the trafficking of LDL-derived substrate in steroidogenic cells; that NPC1 expression is up-regulated when NPC1 action is blocked; and that the NPC1 compartment can be functionally separated from other intracellular pathways contributing substrate for steroidogenesis.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2000

Lecithin vesicular carriers for transdermal delivery of cyclosporin A.

Two kinds of vesicles with and without the presence of sodium cholate (flexible vesicles and conventional vesicles) were prepared, using cyclosporin A as model drug. When applied onto the excised abdominal skin of mice non-occlusively, the enhancing effects of vesicles on the penetration of cyclosporin A were assessed by an in vitro permeation technique. The effect of sodium cholate micelles was also studied. In vivo study was carried out by topical application of vesicles onto the mice skin and drug serum concentration was detected. Results showed that after 8 h of administration, flexible vesicles transported 1.16 microg of cyclosporin A through per cm(2) mice skin and amounted to 1.88 microg 24 h later. The residual amount in the skin was 1.78+/-0.51 microg/cm(2). However, flexible vesicles failed to transport measurable amount of drug through pre-hydrated skin while deposited 2.39+/-0.26 microg/cm(2) into the skin. Conventional vesicles failed to transfer cyclosporin A into the receiver while accumulated 0. 72+/-0.19 microg/cm(2) of drug in the skin. Furthermore, 1 and 40% sodium cholate micelles precluded the transport of cyclosporin A. In vivo studies indicated that with the application of flexible vesicles, serum drug concentration of 53.43+/-9.24 ng/ml was detected 2 h later. After the stratum corneum of mouse skin has been destroyed by shaving, flexible vesicles transferred large amount of drug into blood, up to 187.32+/-53.21 ng/ml after 1 h of application. Conventional vesicles failed to deliver measurable amount of drug into the blood under normal skin condition. In conclusion, flexible vesicle is better than conventional vesicle as the carrier for transdermal delivery of cyclosporin A. Penetration and fusion have been suggested to be two major functional mechanisms. Hydration is detrimental to the enhancement effect. Stratum corneum constitutes main barrier to the transport of lipophilic cyclosporin A.

Administration, Cutaneous↗
PubMed2000

A common polymorphism in the human insulin-like growth factor binding protein 3 gene.

A common polymorphism generated by an A to C transition at nucleotide 7580 in the third intron of the insulin-like growth factor binding protein 3 gene was found. This polymorphism can be identified by Nde 1 restriction of genomic DNA amplified with a specifically designed restriction enzyme site-generating oligonucleotide primer. The frequency of the A and C alleles was estimated at 0.6 and 0.4 in the Caucasians, 0.63 and 0.37 in Blacks, respectively.

Amino Acid Substitution↗
PubMed2000

Pore sizes in hydrated dextran microspheres.

The average pore size of hydrated dextran microspheres is derived from rheological and protein release data. The microspheres were prepared by cross-linking an aqueous solution of methacrylated dextran emulsified in a continuous poly(ethylene glycol) phase. The rheological data were obtained using a novel micromanipulation technique, which enables the compression of a single microsphere. The so obtained pseudoelasticity moduli of the microspheres were derived from these compression data and corresponded well with the elasticity moduli of macroscopic hydrogels of the same composition, as determined with dynamic mechanical analysis. The modulus increased with decreasing water contents of the microspheres and with increasing degrees of methacrylate substitution of the dextran used. Furthermore, the average pore sizes calculated from the pseudoelasticity moduli were in good agreement with the pore sizes derived from protein release data. In conclusion, this study shows that micromanipulation provides insight into the average pore sizes of dextran microspheres, which is an important characteristic that will modulate the release of encapsulated proteins.

Dextrans↗
PubMed2000

Distribution of three HIV-1 resistance-conferring polymorphisms (SDF1-3'A, CCR2-641, and CCR5-delta32) in global populations.

Chemokine receptors (CCR5, CXCR4 and CCR2) have been shown to be important co-receptors for HIV infection. Mutations at CCR5 (CCR5-delta2), CCR2 (CCR2-641), and stromal-derived factor SDF1 (SDF1-3'A), a primary ligand for CXCR4, are known to have protective effects against HIV-1 infection and the onset of AIDS symptoms. We studied the three-locus genotype frequency distributions in 70worldwide populations from a sample of 2341 individuals without any known history of HIV-1 infection and AIDS symptoms. From these data, we estimated the risk of AIDS onset (relative hazard, RH) of each population. This survey shows that the substantial allele frequency differences of each of these mutations translate into an extensive variation in relative hazards for AIDS in worldwide populations. However, no evidence of natural selection against the mutant gene carriers is detected. Finally, the combined three-locus genotype data predict the highest relative hazard (RH) in South-East Asia and Africa where AIDS is known to be more prevalent.

Chemokine CXCL12↗
PubMed2000

Interactions among the alpha2-, beta2-, and beta3-adrenergic receptor genes and obesity-related phenotypes in the Quebec Family Study.

The gene-gene interactions between markers in the alpha2-, beta2-, and beta3-adrenergic receptor (ADR) genes and obesity-related phenotypes were studied in the Quebec Family Study (QFS) cohort. The prevalence of the Arg allele of the Arg16Gly polymorphism in the beta2-ADR gene was higher (49%) in males with a body mass index (BMI) of 35 kg/m2 or higher versus those with a BMI less than 35 kg/m2 (33%; P = .010). The beta2-ADR gene Arg16Gly and Gln27Glu polymorphisms were associated with plasma total and low-density lipoprotein (LDL) cholesterol concentrations. In addition, the homozygotes for the 6.3-kb allele of DraI polymorphism in the alpha2-ADR gene had the lowest mean abdominal subcutaneous fat area (P = .012) and total fat area (P = .003), as well as insulin area, under the curve during an oral glucose tolerance test ([OGTT] P = .004). Several ADR gene-gene interaction effects on abdominal fat distribution and plasma lipids were detected. First, significant interactions between alpha2- and beta3-ADR genes were observed on total (P = .015) and subcutaneous (P = .004) abdominal fat. Second, interaction effects between alpha2- and beta2-ADR gene variants influenced total, high-density lipoprotein (HDL), and LDL cholesterol concentrations. Finally, there were interactions between markers within the beta2-ADR gene affecting plasma triglyceride concentrations and subcutaneous abdominal fat. From these results, we conclude that polymorphisms in the ADR genes contribute to body fat and plasma lipid variability in men. Gene-gene interactions among the ADR genes contribute to the phenotypic variability in abdominal obesity and plasma lipid and lipoprotein, but not in visceral fat levels.

Abdomen↗
PubMed2000

Long-term survey of outcome in acute promyelocytic leukemia.

OBJECTIVE: To investigate all-trans retinoic acid (ATRA) and As2O3 which were found to be able to selectively induce differentiation and apoptosis in acute promyelocytic leukemia (APL) and recently became standard treatment for de novo or relapsed APL. The results of long-term follow up in 72 APL patients were presented and prognostic factors discussed. METHODS: Seventy-two newly-diagnosed patients with APL entering CR with ATRA were consolidated with chemotherapy alone (31 patients), ATRA + chemotherapy (30 patients) and ATRA alone (11 patients). Univariate analysis was done to identify the potential prognostic factors. A total of 40 cases of patients relapsed after their first complete remission, including 3 groups of patients: group A, patients treated with ATRA and chemotherapy after relapse (8 patients); group B patients treated with As2O3 alone for 2nd CR and consolidation (21 patients); group C patients treated with As2O3 for 2nd CR and both As2O3 and chemotherapy for consolidation (11 patients). Univariate analysis was also done to identify the potential prognostic factors. RESULTS: With a median follow-up of 45 months (5-75 months), the median event-free survival was 21 months and median overall survival was not achieved. The estimated 3- and 5-year event-free survival (EFS) and over-all survival (OS) were 32.5 +/- 10.5%, 18.4 +/- 7.5% and 73.8 +/- 17.5%, 58.5 +/- 15.2%. In denovo patients, the combination of ATRA and chemotherapy in both induction and post-remission treatment was found to be statistically significant for EFS (P = 0.023), and initial peripheral leukocyte count was significantly related to OS. In relapsed patients, only the treatment of As2O3 with or without chemotherapy in consolidation after relapse was statistically significant for CR and both EFS (P = 0.0061) and OS (P = 0.0013). CONCLUSION: ATRA is an effective induction therapy and can be considered as first choice of treatment in denovo APL. Addition of chemotherapy in both induction and post-remission therapy can delay or decrease the possibility of relapse compared to ATRA alone. As2O3 is an effective agent for relapsed APL and remains an important prognostic factor for relapsed APL.

Adolescent↗
PubMed2000

Superoxide generation and tyrosine kinase.

NADPH oxidase is a multi-subunit enzyme complex responsible for superoxide generation in many cells, for example, B-lymphocytes and osteoclasts. NADPH oxidase is localized on the cell surface and generates superoxide extracellularly. After synthesis, components of this oxidase are transported to the cell membrane where the functional NADPH oxidase complex is assembled. The mechanism by which the membrane-bound components are transported to the cell surface of osteoclasts remains unclear. In this study, we examined the role of tyrosine kinase activity in the transport of NADPH oxidase components. When B-lymphocytes and osteoclasts were treated with herbimycin A, a specific inhibitor of tyrosine kinase, superoxide production was significantly decreased. The amount of p91, the catalytic subunit of NADPH oxidase, was decreased in the cellular membrane of herbimycin A treated cells compared to untreated controls. Similar results were obtained for the movement of a regulatory subunit of the NADPH oxidase complex, p47, in B-lymphocytes. Thus, inhibition of tyrosine kinase decreases superoxide production by disrupting the translocation of the NADPH oxidase complex.

Animals↗
PubMed2000

[The application of polymerase chain reaction-single strain conformation polymorphism in the pedigree analysis of familial hypercholerolemia patients].

OBJECTIVE: To discuss the value of polymerase chain reaction-single strand conformation polymorphism(PCR-SSCP) in the pedigree analysis of familial hypercholesterolemia(FH) patients. METHODS: For 4 patients with FH detected by PCR-SSCP and DNA sequence analysis (1 homozygote has point mutation in exon 7, 1 heterozygote in exon 14, and 2 heterozygotes in 3' part of exon 4 ), members of each pedigree, altogether 23 individuals, were analysed using PCR-SSCP. RESULTS: Every member of the 4 pedigrees was examined genetically. Besides the 4 probands, another 1 homozygote and 8 heterozygotes were found. CONCLUSION: The PCR-SSCP method can be used in the pedigree analysis of FH probands. The early diagnosis of siblings and relatives can help to provide genetic consultation and direction so as to pay attention to development of hypercholesterolemia.

Adolescent↗
PubMed2000

The role of lasers in cosmetic dentistry.

Dental lasers contribute significantly to the field of cosmetic dentistry, providing an invaluable resource for clinicians who perform different types of esthetic procedures. Practitioners in this specialized field not only help patients acquire beautiful and ideal smiles and dental health, but also they assist patients in benefiting from tremendous clinical advantages, such as sterile surgical sites and increased comfort levels. Tooth whitening will always be an important component of cosmetic dentistry. Developing the most efficient and safe method of tooth whitening is the goal of power bleaching. Currently the argon laser has proved to be the most valuable energy source for power bleaching. Clinicians need to learn more about constantly updated technology and apply newly discovered methods and protocols to clinical situations to benefit patients and clinicians.

Adolescent↗
PubMed2000

[The diagnosis and treatment of microgenia].

OBJECTIVE: This article is to elucidate the indications of horizontal advancement osteotomy of the mandible or bone grafting for microgenia. METHODS: After understanding the characteristics of a patient's inferior one-third facial malformation through physical and cephalometric measurement, we correct the malformation of moderate or serious degree with osteotomy genioplasty. RESULTS: Eight patients received the operation and obtained good results. CONCLUSION: Understanding the characteristics of microgenia and choosing a rational method is the prerequisite for a good operative result.

Adult↗
PubMed2000

[Response of wheat seedlings with different drought resistance to water deficiency and NaCl stresses].

The growth, photosynthesis, transpiration and antioxidative defence system of the seedlings of drought-tolerant wheat strain 8139 and drought-sensitive strain Ganmai No. 8 at 20% PEG 6000 and 1.2% NaCl stresses were compared. The results showed that strain 8139 had a strong drought resistance, but a weak salt resistance. The root growth of both wheat strains was inhibited significantly under salt stress, but stimulated slightly under drought stress. The net photosynthetic rate and water use efficiency of strain 8139 were significantly different from those of Ganmai No. 8 at every stage under both drought and salt stresses, and its transpiration rate was significantly different from that of Ganmai No. 8 only at 7th and 14th day after being stressed. The MDA content in strain 8139 after being stressed for 7 days was much lower than that in Ganmai No. 8 under drought stress, but there was no significant difference between the two strains under NaCl stress. Correspondingly, there was no significant difference in the fructan content and SOD and APX activities between strain 8139 and Ganmai No. 8, but a significant difference in GSH content was found under salt stress. Under drought stress, the contents of fructan and GSH and the activities of SOD and APX in strain 8139 were much higher than those in Ganmai No. 8 at different stage, and strain 8139 exhibited a strong antioxidative defence ability.

Disasters↗
PubMed2000

[A comparative study on chlorophyll content, chlorophyll fluorescence and diurnal course of leaf gas exchange of two ecotypes of banyan].

The morphological differences, chlorophyll contents, fluorescence and diurnal course of leaf gas exchange between terrestrial banyan and amphibious banyan were compared with pot culture. The amphibious banyan possesses well developed aerial and hydro-adventitious roots, and wider leaf with inclination of evolution toward mesophytic traits. The chlorophyll content of terrestrial banyan was higher than that of amphibious banyan. The diurnal course of leaf gas exchange indicated that net photosynthetic rate of terrestrial banyan was slightly higher than that of amphibious banyan grown in water, but much higher than that grown in soil. The amphibious banyan grown in water had the highest transpiration rate, the terrestrial banyan had a lower one, and the amphibious banyan grown in soil had the lowest. Linear regression analysis showed a positive correlation between net photosynthetic rate and stomatal conductance, implying that the stomatal conductance was dominant factor controlling the gas exchange. In this study, the term of intrinsic water use efficiency (net photosynthetic rate/stomatal conductance ratio, Intrinsic WUE) was applied to describe the photosynthesis and water properties, and the result showed that it was a more suitable measure compared to the usual WUE(net photosynthetic rate/transpiration rate). Among the three banyan plants examined, the amphibious banyan had the highest intrinsic WUE.

Adaptation, Physiological↗
PubMed2000

Impact of RT-PCR monitoring on the long-term survival in acute promyelocytic leukemia.

OBJECTIVE: To evaluate the impact of kinetics of molecular remission via retro-transcriptase polymerase chain reaction (RT-PCR) assay on the long-term survival in patients with acute promyelocytic leukemia (APL). METHODS: Seventy patients with newly-diagnosed APL in remission were involved in this study. Monitoring of minimal residual disease (MRD) was performed regularly by RT-PCR assay for PML-RAR alpha during consolidation. RESULTS: A 5-year relapse-free survival (RFS) and overall-survival (OS) were estimated as 46.8% +/- 8.4% and 69.9% +/- 9.4% for the whole group. Fifty-two (74.3%) patients got negative RT-PCR result at least once. Serial monitoring of RT-PCR was available in 38 cases and 24 (63.2%) patients presented with persistent negative PCR results. The achievement and continuous negative RT-PCR result was significantly related to the RFS. CONCLUSIONS: Achievement of negative RT-PCR in remission is associated with favorable RFS and OS. Continuous negative RT-PCR results are associated with long-term relapse-free survival and may be considered as potentially curative. RT-PCR assay for detection of MRD should be performed regularly during post-remission period as an important prognostic factor.

Adolescent↗
PubMed2000

[Influence of feiliuping No. 2 on platelet surface glycoprotein expression in mid-late stage lung cancer patients].

OBJECTIVE: To explore the influence of Feiliuping NO. 2 (FLP), a Chinese herbal preparation for reinforcing Qi, nourishing Yin, activating blood circulation and detoxifying, on surface glycoprotein expression (SGPE) and activated condition of platelet in mid-late stage lung cancer patients. METHODS: Changes of platelet surface expression of CD41/CD42a, CD36/TSP, CD62/CD63, CD9 and CD31 were measured before and after FLP treatment by using flow cytometer in 30 cases of mid-late stage lung cancer. RESULTS: The SGPE and activated condition of platelet in mid-late stage lung cancer patients were significantly higher than those of healthy person, and both could be reduced partly by FLP. CONCLUSION: FLP could influence the SGPE and activate condition of platelet in lung cancer patients.

Adult↗
PubMed2000

[Microcirculation of thoraco-acromial flaps: monitoring and clinical application].

OBJECTIVE: To monitor the microcirculation of thoraco-acromial flaps. METHODS: The microcirculation in 12 thoraco-acromial flaps was monitored continuously by laser Doppler flowmetry (LDF). RESULTS: The microcirculatory changes in thoraco-acromial flaps were divided into two phases: rapid rising (2 - 4 days after operation) and plateaurising (4 - 7 days after operation). PU values were 7.4 +/- 2.0, 7.6 +/- 2.3 and 7.3 +/- 1.6. CONCLUSIONS: In division of the thoraco-acromial flaps within the plateau, the value (PU) returned to or exceeded 50% of that before application of the tourniquet. All flaps survived. The time of division was decreased to 6 - 8 after operation days.

Adolescent↗
PubMed2000

[Acute mesenteric vein thrombosis: diagnosis and management].

OBJECTIVE: To evaluate the progress in diagnosis and management of acute mesenteric vein thrombosis (AMVT). METHODS: Fifteen patients with AMVT treated from January 1983 to November 1998 were reviewed retrospectively. They were 7 men and 8 women, aged on average 42 years. The duration from onset of symptoms to admission was 24 - 168 hours (mean 84 hours). RESULTS: Six patients were diagnosed before operation, while 9 during laparotomy. Two patients received conservative treatment and the rest underwent surgery. The average length of bowel resection was 300 cm. All the patients received anticoagulation therapy with heparin immediately after operation. Local thrombolytic therapy was given to 4 patients. Four patients died in hospital and two had sequelae of short bowel syndrome. CONCLUSIONS: AMVT is rare but a potentially lethal emergency disease. Early diagnosis, anticoagulation and appropriate surgical approach are essential to improve the prognosis. It is important to keep vigilance for AMVT in the patients in the hypercoagulation status, especially when the symptoms are inconsistent with abdominal signs. Color-US and CT appear to be sensitive in the diagnosis of this condition. Local thrombolytic therapy will be effective. Second-look is a necessarily procedure for reserving the bowel that may be alive. Laparoscopy technique will play an important role in the diagnosis and treatment for AMVT.

Acute Disease↗