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Biomedical subjects

M Lin

Publications and source records attributed to M Lin.

At least 37 records · Page 2Linked to original sources
PubMed2001

PCR genome walking identifies a genetic locus comprising two heat shock genes (hslV and hslU) from Leptospira borgpetersenii serovar hardjobovis.

PCR walking on genomic DNA of Leptospira borgpetersenii serovar hardjobovis has identified a genetic locus comprising two heat shock genes (hslV and hslU). This is the first molecular study on hslV and hslU in a Leptospira species. The hslV gene has an open reading frame (ORF) of 543 bp coding for a 180-amino acid polypeptide (19.476 kD) with 49-62% identity to other bacterial HslV homologs. Forty-three nucleotides downstream from the hslV stop codon was found a second heat shock gene hslU with an ORF of 1401 bp encoding a 53.139-kD polypeptide of 467 amino acids with 49-56% identity to the HslU homologs from other bacteria. An Escherichia coli-like ribosome binding site (RBS) and a final sigma32-like heat shock promoter sequence were present upstream of both heat shock genes. Identification of the hslV and hslU genes in a Leptospira species and the high degree of similarity of the encoded proteins to the E. coli homologs suggest that the encoded HslV and HslU proteins function as forming an ATP-dependent protease complex as in E. coli.

ATP-Dependent Proteases↗
PubMed2001

Diels-Alder type adducts from Morus cathayana.

Two natural Diels-Alder type adducts, cathayanon A (1) and cathayanon B (2), resembling sanggenon C (4) and O (3), were isolated from the root bark of Morus cathayana. Their structures were elucidated on the basis of spectroscopic evidence. The structure of 1 was confirmed by the results of X-ray crystallographic analysis. The absolute configurations of 1 and 2 were determined as 2S, 3R,14S, 19S, 20R and 2S, 3R, 14R, 19S, 20R, respectively. The absolute configurations at C-2 and C-3 of two other known isomeric Diels-Alder adducts sanggenon O (3) and C (4) were deduced as 2R, 3S. Pharmacological tests indicated that 1 and 2 exhibited potent activities on the inhibition of HL-60 cell adhesion to BAEC at concentrations of 10(-5) mol l(-1), with inhibitory rates of 44.72 and 39.02%, respectively.

Anti-Inflammatory Agents↗
PubMed2001

Anti-inflammatory tetramers of resveratrol from the roots of Vitis amurensis and the conformations of the seven-membered ring in some oligostilbenes.

Five resveratrol tetramers, amurensins I-M, were isolated from the roots of Vitis amurensis (Rupr.), together with five known resveratrol tetramers, (+)-hopeaphenol, isohopeaphenol, vitisin A, (+)-vitisifuran A, and heyneanol A. Their structures and stereochemistry were determined by chemical and spectroscopic methods, especially by use of 2D NMR analysis. Some of them had an ampelopsin A or a balanocarpol unit, in which the conformations of the seven-membered carbon ring were described for the first time. The anti-inflammatory activities of the tetramers were also tested. Among them, (+)-hopeaphenol, isohopeaphenol, vitisin A, (+)-vitisifuran A and heyneanol A showed potent inhibition on the biosynthesis of leukotriene B4 (LTB4), and amurensins I and L showed strong antagonism of the histamine acceptor.

Anti-Inflammatory Agents↗
PubMed2001

Stilbenoids from the lianas of Gnetum pendulum.

Two stilbenoids, gnetupendin A and B, were isolated from the lianas of Gnetum pendulum C. Y. Cheng, together with four known compounds, resveratrol, isorhapontigenin, shegansu B and beta-daucosterol. Their structures were determined on the basis of analysis of spectral evidence, especially 2D NMR spectroscopic techniques.

Plants↗
PubMed2001

Equilibrium and kinetics of metal ion adsorption onto a commercial H-type granular activated carbon: experimental and modeling studies.

Systematic studies on metal ion adsorption equilibrium and kinetics by a commercial H-type granular activated carbon were carried out. Titration of the carbon showed that the surface charge density decreased with an increasing pH. Higher copper adsorption was obtained with increasing solution pH and ionic strength. Metal removal was in the descending order: Cu2+ > Zn2+ approximately Co2+. Copper removal was not affected by addition of zinc or cobalt, while copper can reduce both zinc and cobalt removal. Kinetic experiments demonstrated that the copper adsorption rapidly occurred in the first 30-60 min and reached the complete removal in 3-5 h. Removal of zinc and cobalt was slightly slower than that of copper. It was found that the mass transfer is important in the metal adsorption rate. The surface complex formation model was used successfully to describe the surface change density, as well as the single- and multi-species metal adsorption equilibrium. The copper removal was due to adsorption of Cu2+, CuOH+, and CuCl+, while the zinc and cobalt uptake was due to the formation of surface metal complexes of SOM2+ and SOMOH+ (M = Zn and Co). It was found that the diffusion-control model well described the adsorption kinetics with various metal ions and pH values. Finally sensitivity analysis on the kinetic model's parameters was carried out.

Adsorption↗
PubMed2001

Transforming growth factor-beta1 adsorbed to tricalciumphosphate coated implants increases peri-implant bone remodeling.

Increasing experimental interest has emerged for the use of growth factors to stimulate bone healing and bone formation in various clinical situations. We and others have demonstrated that recombinant human transforming growth factor-beta1 (rhTGF-beta1) adsorbed onto tricalcium phosphate (TCP)-coated implants can improve mechanical fixation and bone ongrowth. The present study evaluated bone remodeling in newly formed bone and adjacent trabecular bone around TCP-coated implants with and without rhTGF-beta1 adsorption. Unloaded cylindrical grit-blasted titanium alloy implants coated with TCP were inserted bilaterally into the femoral condyles of 10 skeletally mature mongrel dogs. The implants were initially surrounded by a 2 mm gap. Implants with 0.3 microg rhTGF-beta1 were compared with implants without growth factor. The dogs were sacrificed after six weeks. Bone remodeling was evaluated by histomorphometry on Goldner-stained undecalcified sections. The bone volume in the gap was increased significantly from 17.6% in the control group to 25.6% in the rhTGF-beta1 group (p = 0.03). Also bone surface was increased in the rhTGF-beta1 group. The osteoclast covered surfaces were increased from 3.6% in the control group to 5.9% in the rhTGF-beta1 group (p = 0.02). In the surrounding trabecular bone no significant changes in bone remodeling parameters was demonstrated. This study suggests that rhTGF-beta1 adsorbed onto TCP-ceramic coated implants accelerates repair activity in the newly formed bone close to the implant, but it does not seem to influence bone remodeling in preexisting bone at a greater distance from the implant.

Adsorption↗
PubMed2001

Acute and subacute toxicity and efficacy of S-nitrosylated captopril, an ACE inhibitor possessing nitric oxide activities.

The toxicity and efficacy of S-nitrosocaptopril (CapNO), a novel vasodilator possessing the capacities of both a nitric oxide donor and an angiotensin converting enzyme (ACE) inhibitor, were examined in rodents. In single-dose acute toxicity studies in ICR mice, the median lethal dose (LD(50)) for CapNO was 674+/-94 mg/kg (iv) and 2078+/-100 mg/kg (po), whereas for oral captopril was 4286+/-173 mg/kg. S-nitrosoglutathione, containing the same S-nitroso moiety as CapNO, showed an LD(50) equal to CapNO when the values were expressed by the mol/kg. The cause of acute death by the high doses of CapNO was lethal hypotension. In the subacute toxicity studies, oral CapNO was well tolerated in normotensive and hypertensive rats at doses up to 500 mg/kg/day for 3 months, except for considerable reductions in food consumption and growth rate observed in the 500 mg/kg/day group. Serum chemistry and hematology tests performed in the subacute toxicity studies revealed no adverse effects of oral CapNO except for a significant decrease in cholesterol levels in hypertensive SHR rat. At autopsy, no histopathological changes in major organs were observed over the subacute period. Administration of a therapeutic dose of CapNO (iv, 250 microg/kg which produced 25% decreases in blood pressure) revealed no changes in the hematological parameters. Subchronic treatment of SHR and SS/Jr rats with oral CapNO (50 mg/kg/day) significantly reduced mean arterial pressure to the normotensive level. Considering the absence of adverse effects of CapNO in the subchronic toxicity study, CapNO appears to be a safe drug for further clinical trials, but particular caution must be taken because it can cause hypotension when overdosed.

Administration, Oral↗
PubMed2001

The origin of Minnan and Hakka, the so-called "Taiwanese", inferred by HLA study.

The Minnan and Hakka people groups, the so-called "Taiwanese", are the descendants of early settlers from the southeast coast of China during the last few centuries. Genetically they showed affinities to southern Asian populations, as determined by phylogenetic trees and correspondence analysis calculated from HLA allele frequencies. This corresponds historically with the fact that they are the descendants of the southeast coastal indigenous population (Yueh) of China and should therefore not be considered as descendants of "pure" northern Han Chinese. A33-B58-DRB1*03 (A33-Cw10-B58-DRB1*03-DQB1*02), the most common HLA haplotype among "Taiwanese", with a haplotype frequency of 6.3%, has also been found to be the most common haplotype among Thai-Chinese and Singapore Chinese, two other populations also originating from the southeast coast of China. These observations suggests that this haplotype is the most well-conserved ancient haplotype of the Yueh.

Alleles↗
PubMed2001

Diversity of HLA among Taiwan's indigenous tribes and the Ivatans in the Philippines.

Taiwan's indigenous tribes, especially the east coast tribes are not only closely related to Oceania but also with the Australian aborigines. The Ivatans of the Batan Islands in the Philippines are closely related to the Yami tribe of Taiwan as cultural and anthropological studies have shown. Many DRB1 alleles (*15021, *16021, *0404, *04051, *11011, *12021, *1401, *08032) have high allele frequencies (>20%) in certain tribes, suggesting Taiwan's indigenous tribes are homogeneous populations. These high frequency DRB1 alleles and also some HLA-A-B-DR haplotypes found in Taiwan's indigenous tribes are also found in Oceania, Australian aborigines, south and north east Asians and American Indians, lending further support to our previous findings that Taiwan's indigenous tribes are more or less genetically related to both northern and southern Asians, possibly as well as Amerindians. HLA-A*2402 with a remarkably high frequency among Taiwan's indigenous tribes (52.1% approximately 86.3%), especially the central mountain tribes, possibly represents not only founder effects and population bottlenecks, but also positive selection of the allele. Although the Ami tribe has the highest ever reported frequencies of the DRB1*0404 and DRB1*0405, these alleles have not been found to be associated with rheumatoid arthritis as previously described for Caucasians. In addition, DRB1*1401 has a high frequency in most tribes but is not associated with psoriasis as previously indicated in some studies, suggesting the involvement of some additional genetic and/or environmental factors mechanism in the development of these diseases.

Alleles↗
PubMed2001

Asian American college students as model minorities: an examination of their overall competence.

Educational success among Asian Americans has led to their being labeled the "model minority." At the University of California, Berkeley (UCB), Asian American students have higher grade point averages (GPAs) than Hispanic and African American but not White students, supporting the notion that Asian Americans are more successful compared with other racial minorities. However, success in the classroom does not implicate effective functioning in life, and nonacademic criteria ought to be considered in assessing the validity of the model minority image. Given the increasing diversification of the United States, cross-racial engagement may be an additional contributor to overall competence. This was empirically tested in a group of 642 undergraduates at UCB, including 291 Asian, 197 White, 20 African American, 67 Hispanic, and 56 multiracial students. Overall competence was operationalized by sense of coherence, that is, the extent to which the world is experienced as comprehensible, manageable, and meaningful (A. Antonovsky, 1979, 1987). As predicted, Asian Americans had significantly fewer numbers of cross-racial groups represented in their friendship network than did students of all other races. Lower cross-racial engagement and being Asian (as compared with White) were related to a lower sense of coherence, whereas lower GPA was not. Within the Asian American subsample, cross-racial engagement was again significantly associated with greater coherence, whereas GPA again was not. Thus, extending the definition of success to overall competence, these findings raise questions about the applicability of the model minority label to Asian Americans, despite their academic achievement. Future studies need to assess the reasons for their limited cross-racial engagement and lower sense of coherence and to examine means to assist the development of these strengths.

Achievement↗
PubMed2001

Apolipoprotein B secretion and atherosclerosis are decreased in mice with phospholipid-transfer protein deficiency.

Increased secretion and levels of ApoB-containing lipoproteins (BLp) commonly occur in familial hyperlipidemia, obesity and diabetes. The plasma phospholipid-transfer protein (PLTP) is known to mediate transfer of phospholipids between BLp and HDL during their intravascular metabolism. To address a possible role of PLTP in dyslipidemia and atherogenesis, we bred mice deficient in the gene encoding PLTP (PLTP-deficient mice) using different hyperlipidemic mouse strains. In ApoB-transgenic and ApoE-deficient backgrounds, PLTP deficiency resulted in reduced production and levels of BLp and markedly decreased atherosclerosis. BLp secretion was diminished in hepatocytes from ApoB-transgenic PLTP-deficient mice, a defect that was corrected when PLTP was reintroduced in adenovirus. The studies reveal a major, unexpected role of PLTP in regulating the secretion of BLp and identify PLTP as a therapeutic target.

Animals↗
PubMed2001

Apoptotic response to homoharringtonine in human wt p53 leukemic cells is independent of reactive oxygen species generation and implicates Bax translocation, mitochondrial cytochrome c release and caspase activation.

In the present study, we investigated the in vitro apoptotic response of leukemic cells to the cellular stress induced by homoharringtonine (HHT), a plant alkaloid with antileukemic activity which is currently being tested for treatment of acute and chronic leukemias. A comparison of leukemic cell lines with different p53 gene status revealed a considerably higher sensitivity to HHT-induced apoptosis in the cells with a wt p53, and apoptotic events in wt p53 leukemia cells (MOLT-3 cell line) were studied in more detail. To this end, we examined components of apoptotic cascades including Bax expression and its intracellular localization, changes of mitochondrial membrane potential (MMP), reactive oxygen species (ROS) levels, cytochrome c release from mitochondria and activation of caspases. Bax protein levels did not increase despite an up-regulation of bax at mRNA level. However, Bax translocation from cytosol towards mitochondria was observed. In addition, we observed a release of cytochrome c from the mitochondria, and the localization changes of both Bax and cytochrome c were found already at the early, annexin V-negative stage of HHT-induced apoptosis. HHT-treated MOLT-3 cells revealed loss of MMP as well as activation of caspases demonstrated by DEVD-, IETD- and LEHD-tetrapeptide cleavage activity in the cell lysates. ROS levels only slightly increased in HHT-treated cells and antioxidants did not prevent apoptosis and MMP changes. Therefore, wt p53 leukemic cells respond to HHT-specific cellular stress by induction of ROS-independent apoptotic pathway characterized by translocation of Bax, mitochondrial cytochrome c release and activation of caspases.

Antioxidants↗
PubMed2001

Actin polymerisation during morphogenesis of the acrosome as spermatozoa undergo epididymal maturation in the tammar wallaby (Macropus eugenii).

In the tammar wallaby (Macropus eugenii), post-testicular acrosomal shaping involves a complex infolding and fusion of the anterior and lateral projections of the scoop-shaped acrosome into a compact button-like structure occupying the depression on the anterior end of the sperm nucleus. The present study has generated cytochemical and histological evidence to demonstrate that the occurrence of actin filaments (F-actin, labelled by Phalloidin-FITC) in the acrosome of tammar wallaby spermatozoa is temporally and spatially associated with the process of acrosomal shaping in the epididymis, through a pool of monomeric actin (G-actin, labelled by Rh-DNase I) present in the acrosome throughout all stages of epididymal maturation. F-actin was not detected in the acrosome of testicular spermatozoa, but was found in the infolding and condensing acrosome of caput and corpus epididymal spermatozoa. When the spermatozoa completed acrosome shaping in the cauda epididymidis, F-actin disappeared from the acrosomal area. The strong correlation between the occurrence of F-actin and the events of acrosomal shaping suggested that the post-testicular shaping of the acrosome might depend on a precise succession of assembly and disassembly of F-actin within the acrosome as the spermatozoa transit the epididymis. Thus, actin filaments might play a significant role in the acrosomal transformation, as they are commonly involved in morphological changes in somatic cells.

Acrosome↗
PubMed2001

Polymorphism and distribution of the Secretor alpha(1,2)-fucosyltransferase gene in various Taiwanese populations.

BACKGROUND: The Secretor gene (Se or FUT2), which produces alpha(1,2)-fucosyltransferase, exhibits extensive polymorphism. Six Se genes, including the weak Se (Se(w) or Se385) and three nonsecretor alleles (se571, se685, and se849) have been detected in various populations of Taiwan. The distribution of various Lewis phenotypes among the Taiwanese population groups has been shown to vary considerably. STUDY DESIGN AND METHODS: A PCR-RFLP analysis system, which was based on the nucleotide polymorphism variation of the different Se alleles and which can reveal the Se genotype of an individual easily and accurately, was developed. The distribution of the Se alleles among Taiwanese population groups, including the two major populations, Minnan and Hakka Taiwanese, and 11 indigenous groups, was analyzed by the method. RESULTS: Frequencies of the Se alleles among the Taiwanese populations were revealed. The distribution of the nonsecretor alleles, especially se849, showed a marked variation. A good correlation was observed between a person's Se genotype and Lewis phenotype. CONCLUSION: The Se genes have a polymorphic distribution among various Taiwanese populations, and this agrees with previous results for Lewis phenotype distributions. The Se(w) allele and the three se alleles are responsible for the Le(a+b+) and Le(a+b-) phenotypes, respectively.

Fucosyltransferases↗
PubMed2001

The use of genotyping to predict the phenotypes of human platelet antigens 1 through 5 and of neutrophil antigens in Taiwan.

BACKGROUND: The human platelet antigen (HPA) 1 through 5 and the human neutrophil antigen (HNA-1) systems are relevant to immune-related thrombocytopenia and neutropenia. The alloantigen distribution profiles in the population will aid in estimating the risk of alloimmunization. STUDY DESIGN AND METHODS: Genotyping of the genes that control the expression of the HPA-1 through -5 and HNA-1 systems in Taiwanese (n = 326) and Taiwan's indigenous peoples (n = 608) was performed by PCR with the sequence-specific primer (PCR-SSP) method. RESULTS: In the HPA system, HPA-1b and HPA-4b were absent among Taiwan's indigenous tribes and detected among other Taiwanese only with frequencies of <0.2 percent and <0.5 percent, respectively. The GP1BA*2 (HPA-2b) and GP1A*2 (HPA-5b) allele frequencies range from 1 percent to 7 percent and 0.4 percent to 3.5 percent among the two ethnic groups, respectively. GP2B*1 (HPA-3a) and GP2B*2 (HPA-3b) showed similar allele frequencies. In the HNA-1 system, the FCGR3B*1 (HNA-1a) allele frequency was about twice that of FCGR3B*2 (HNA-1b) in Taiwanese and also in most of the indigenous tribes. Three FCGR3B (HNA-1) null persons were found in one indigenous tribe (Ami tribe), for an FCGR3B null frequency of 19.8 percent. However, no FCGR3B*3 (HNA-1c) allele was detected in Taiwan. CONCLUSION: The frequencies of HPA-1b, -2b, and -5b in the Taiwanese population were much lower than those among whites. In Taiwan, all of the HNA-1 null found was due to the deletion of the FCGR3B gene, and this deletion may be widely distributed in the Ami tribe.

Antigens, Human Platelet↗
PubMed2001

Development of a competitive ELISA using a truncated E2 recombinant protein as antigen for detection of antibodies to classical swine fever virus.

The sequence encoding a truncated E2 glycoprotein of the Alfort/187 strain of classical swine fever virus (CSFV) was expressed in Escherichia coli using the pET expression system and the recombinant product purified by Ni-NTA agarose affinity chromatography. The antigenicity of this recombinant protein was demonstrated by immunoblot using anti- CSFV-specific antibodies. A monoclonal antibody was produced against the truncated E2 protein and used as competitor in an ELISA for the detection of antibodies to CSFV. Specific antibodies were demonstrated by competitive ELISA (C-ELISA) as early as 21 days post-infection (dpi) in experimentally infected pigs. Seroconversion was demonstrated by C-ELISA and neutralising peroxidase-linked assay (NPLA) in all infected animals by 4 weeks. No cross-reaction with antibodies to bovine viral diarrhoea virus (BVDV) was seen in the C-ELISA using sera from experimentally infected pigs. The C-ELISA is not intended as a substitute for the NPLA. However, it is expected it will be useful for monitoring and prevalence studies. It will also assist in testing a large number of samples in the event of an outbreak.

Animals↗