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Biomedical subjects

M Lin

Publications and source records attributed to M Lin.

At least 19 recordsLinked to original sources
PubMed2002

Change in demographic picture and increase of drug resistance in pulmonarytuberculosis in a 10-year interval in Taiwan.

BACKGROUND: This study was designed to compare the change in demographics, medical characteristics and drug resistance of patients with active pulmonary tuberculosis (TB) between two time periods within a 10-year interval. PATIENTS AND METHODS: We retrospectively reviewed the clinical records and chest radiographs of 1,826 patients with active pulmonary TB for two time periods from 1992-1996 (n = 884) and 1982-1986 (n = 942). RESULTS: The mean age was significantly higher and there were significantly more female patients in the 1992-1996 period than in the 1982-1986 period. In the 1992-1996 period, there were significantly fewer patients with the main complaints of cough, fever and body weight loss at the time of diagnosis but significantly more patients who had diabetes mellitus, obstructive airway disease, cancer other than lung cancer or who were on corticosteroid therapy. During the 1992-1996 period, single drug resistance against isoniazid (INH), rifampin (RIF) and streptomycin increased by 0.5%, 3% and 0.7%, respectively. Multiple drug resistance against both INH and RIF increased by 2% in the 1992-1996 period. A history of pulmonary TB and extensive pulmonary involvement were two significant factors for drug resistance against INH, RIF or ethambutol (EMB). CONCLUSION: In the 1992-1996 period, the mean age of patients and number of female patients significantly increased. There were more patients with diabetes mellitus, obstructive airway diseases, cancer other than lung cancer and prior steroid therapy but fewer patients presenting with classic clinical symptoms of TB. In consideration of the high prevalence and increasing rate of single and multiple drug resistance, we recommend an initial four-drug regimen (INH, RIF, EMB, pyrazinamide) for the treatment of pulmonary TB in Taiwan.

Adolescent↗
PubMed2002

Thymosin-alpha1 and famciclovir combination therapy activates T-cell response in patients with chronic hepatitis B virus infection in immune-tolerant phase.

We examined whether combination therapy with thymosin-alpha1 and famciclovir would induce hepatitis B e antigen seroconversion in patients with chronic hepatitis B infection in the immune-tolerant phase without inducing significant hepatic necro-inflammation. We studied 32 hepatitis B e antigen positive patients in the immune-tolerant phase of infection, treated with 26-weeks combination therapy of famciclovir and thymosin-alpha1 (group 1). Thirty-two patients who received 26-weeks famciclovir monotherapy (group 2) and another 32 patients who received no treatment (group 3), served as controls. Peripheral blood mononuclear cell proliferation and cytokine secretion in response to recombinant HBV core and surface antigen and serial serum HBV-DNA, were assayed. No significant difference in adverse events were observed among the three groups. By week 26, the median reduction in group 1 (0.94 log10 copies/mL) was greater than group 2 (0.70 log10 copies/mL, P < 0.001). Five (15.6%) patients in group 1 at 52 weeks (median range 13-78 weeks) and none in group 2 or 3 experienced hepatitis B e antigen seroconversion (P = 0.053). Sustained serological clearance of hepatitis B e antigen was associated with activation of CD4 positive HBV-specific T-cell reactivity and were of T-helper 1. Hence combination therapy with immunomodulatory agents and nucleoside analogues should be explored.

2-Aminopurine↗
PubMed2002

Niacin treatment of the atherogenic lipid profile and Lp(a) in diabetes.

OBJECTIVE: We tested the hypotheses that niacin is effective for the separate treatments of abnormalities of LDL particle size, HDL2 percentage and Lp(a) without potential negative effects on glycated haemoglobin. RESEARCH DESIGN AND METHODS: The atherogenic lipid profile lipids, such as triglycerides, small, dense LDL cholesterol (LDLc) particle mass, LDL particle size, total HDLc and HDL2 percentage as well as Lp(a), were measured in 42 diabetic patients with abnormalities of LDL particle size, HDL2 percentage and/or Lp(a) levels before and after niacin treatment. LDL particle size and HDL2 were measured using polyacrylamide gradient gel electrophoreses and Lp(a) was measured by enzyme-linked immunoabsorbance assay (ELISA). RESULTS: After niacin treatment, LDL peak particle diameter increased from 252 +/- 7 A to 263 +/- 7 (p < 0.0001), small, dense LDLc particle mass decreased from 27 +/- 11 mg/dL to 15 +/- 4 (p < 0.0001), total HDLc increased from 39 +/- 7 mg/dL to 51 +/- 11 (p < 0.0001), HDL2 as the percentage of total HDLc mass increased from 29 +/- 8% to 45 +/- 10 (p < 0.0001) and Lp(a) decreased from 43 +/- 17 mg/dL to 25 +/- 10 (p < 0.0001). Mean haemoglobin A1c level was improved during treatment from 7.6 +/- 1.8% to 6.5 +/- 1.0 (p < 0.0001) using increased oral agent and insulin treatment doses in more than 90% of the patients. A total of 21% of the patients were unable to tolerate niacin owing to reversible side-effects, and 14% were unable to adhere to the niacin dosing regimen of three times daily. CONCLUSIONS: These data indicate that in diabetic patients, niacin (i) is effective for treating diabetic dyslipidaemias associated with both the atherogenic lipid profile and Lp(a); (ii) must be used with modern and aggressive oral hypoglycaemic agents or insulin treatment; and (iii) is an important drug to treat diabetes dyslipidaemias because of its broad spectrum of effectiveness.

Arteriosclerosis↗
PubMed2002

Expression of a novel reticulon-like gene in human testis.

Identification of genes that are specifically expressed in the adult testis or the fetal testis is important for the study of genes related to the development of the testis. In this study, a human testis cDNA microarray was established. PCR products of 9216 clones from a human testis cDNA library were dotted on a nylon membrane; mRNA from adult and fetal testes were purified and probes were prepared by a reverse transcription reaction with testis mRNA as template. The microarray was hybridized with probes of adult and fetal testes, and 96.8 and 95.4% of clones were positive, respectively. In total, 731 clones were differentially expressed: 592 were highly expressed in adult testis and 139 were highly expressed in fetal testis. Among these genes, a new reticulon (Rtn)-like gene was detected and named Rtn-T. Rtn-T was highly expressed in adult human testis. The cDNA of Rtn-T contains 3491 bp and the putative protein had 968 amino acids. This protein is homologous to the six known members of the Rtn family (KIAA0886, Rtn xL, reticulon 4a, Nogo-A, Nogo-A short form, and brain my043) but was different at the 5' end. All homologues originate from one gene, and result from both different promotor regions and different splicing. Rtn-T lacks the first exon and contains a second exon that is lacking in the other homologues. Rtn-T is shorter than KIAA0886, Rtn xL, reticulon 4a and Nogo-A, but longer than the Nogo-A short form and brain my043. Sequence analysis showed that Rtn-T protein has two hydrophobic regions that may be membrane-spanning domains. Expression profiles showed that Rtn-T is specifically and strongly expressed in testis. The results of the present study indicate that the Rtn-T gene is differentially expressed in adult and fetal testes and encodes a membrane protein that may have a function in testis development.

Adult↗
PubMed2002

Induction of sperm maturation in vitro in epididymal cell cultures of the tammar wallaby (Macropus eugenii): disruption of motility initiation and sperm morphogenesis by inhibition of actin polymerization.

A sperm-epididymal cell co-culture was shown to be capable of inducing the in vitro maturation of spermatozoa from a marsupial species, the tammar wallaby (Macropus eugenii). This system was able to maintain wallaby epididymal epithelial cells in vitro for more than 2 months. The system also enabled immature wallaby spermatozoa to differentiate from a T-shaped to a streamlined form, accompanied by the development of progressive motility after co-culture with epididymal cell monolayers that had been cultured for 7 days. The addition of inhibitors of actin polymerization (latrunculin A or B) to the co-culture system showed that wallaby sperm maturation was impaired by the interruption of actin organization within the immature spermatozoa. These results indicate that actin filaments play a significant role in sperm transformation during post-testicular maturation in marsupials. These observations also indicate that the marsupial co-culture system has the potential to greatly increase understanding of sperm-epididymal cell interactions and the mechanism of sperm maturation in these species.

Actins↗
PubMed2001

Molecular basis of the adult i phenotype and the gene responsible for the expression of the human blood group I antigen.

The human blood group i and I antigens are characterized as linear and branched repeats of N-acetyllactosamine, respectively. Conversion of the i to the I structure requires the activity of I-branching beta-1,6-N-acetylglucosaminyltransferase (IGnT). Thus the blood group I gene is assigned to encode a beta-1,6-N-acetylglucosaminyltransferase; however, its identity has not been confirmed. The null phenotype of I, the adult i phenotype, provides a means to identify the I gene. Interestingly, the adult i phenotype has been noted to be associated with congenital cataracts in Asians. Molecular genetic studies of 3 adult i pedigrees are reported here. The results obtained on mutation detection within the 2 I-branching enzyme encoding genes, segregation analyses, and enzyme function assays identify molecular changes associated with the adult i phenotype. The adult i phenotype in 2 of the pedigrees studied resulted from 1043G-->A and 1148G-->A mutations, which predict Gly348Glu and Arg383His alterations, respectively, in the IGnT gene. These amino acid changes abolished the original GlcNAc-transferase activity. Deletion of the IGnT gene was observed in the person with adult i phenotype in the third pedigree. These findings suggest that the IGnT gene, first reported in 1993, is the candidate for the blood group I gene. Confirmation of the blood group I gene will further assist in the investigations of the molecular genetics that control I antigen expression in secretions and the molecular basis for the association of the adult i phenotype with congenital cataracts in Asians.

Adult↗
PubMed2001

COX-2 expression in dysplasia of the head and neck: correlation with elF4E.

BACKGROUND: COX-2 inhibitors have shown promise in chemoprevention of epithelial tumors. eIF4E is a biomarker that has identified individuals at high risk for relapse after definitive treatment for head and neck squamous cell cancer (HNSCC). Hence, the authors wanted to determine if COX-2 is expressed in dysplasia of the head and neck and to study the correlation of expression of COX-2 with eIF4E as a potential surrogate endpoint for determining response to COX-2 inhibitors. METHODS: The authors studied the expression of COX-2 and eIF4E in normal epithelium (n = 8), dysplasia (n = 51), mucosa adjacent to tumors (n = 11), and cancer of the head and neck (n = 19) using immunohistochemistry. In addition, Western blot analysis was performed on a subset of the above patient samples and HNSCC cell lines. RESULTS: Immunohistochemical analysis showed expression of COX-2 and eIF4E in all cancers and no expression in normal tissues. In dysplastic epithelium, there was a significant correlation between the expression of eIF4E and COX-2 for all groups of dysplasia combined (chi-square = 40.3, P < 0.001). A Cochran-Armitage trend test showed a significant increase in the proportion of cases that expressed both molecular markers with increasing grades of dysplasia (P = 0.001). Western blot analysis showed increased expression of COX-2 and eIF4E in tumors compared with adjacent mucosa. All three HNSCC cell lines analyzed had increased expression of eIF4E, although only two had increased COX-2 expression. CONCLUSIONS: Expression of COX-2 in dysplasia suggested that COX-2 inhibitors may play a role in chemoprevention of head and neck cancers and that the correlation of Cox-2 with eIF4E indicates that eIF4E can be a potential surrogate marker in chemoprevention trials.

Anticarcinogenic Agents↗
PubMed2001

The S4-S5 linker couples voltage sensing and activation of pacemaker channels.

Voltage-gated channels are normally opened by depolarization and closed by repolarization of the membrane. Despite sharing significant sequence homology with voltage-gated K(+) channels, the gating of hyperpolarization-activated, cyclic-nucleotide-gated (HCN) pacemaker channels has the opposite dependence on membrane potential: hyperpolarization opens, whereas depolarization closes, these channels. The mechanism and structural basis of the process that couples voltage sensor movement to HCN channel opening and closing is not understood. On the basis of our previous studies of a mutant HERG (human ether-a-go-go-related gene) channel, we hypothesized that the intracellular linker that connects the fourth and fifth transmembrane domains (S4-S5 linker) of HCN channels might be important for channel gating. Here, we used alanine-scanning mutagenesis of the HCN2 S4-S5 linker to identify three residues, E324, Y331, and R339, that when mutated disrupted normal channel closing. Mutation of a basic residue in the S4 domain (R318Q) prevented channel opening, presumably by disrupting S4 movement. However, channels with R318Q and Y331S mutations were constitutively open, suggesting that these channels can open without a functioning S4 domain. We conclude that the S4-S5 linker mediates coupling between voltage sensing and HCN channel activation. Our findings also suggest that opening of HCN and related channels corresponds to activation of a gate located near the inner pore, rather than recovery of channels from a C-type inactivated state.

Alanine↗
PubMed2001

Long-QT syndrome-associated missense mutations in the pore helix of the HERG potassium channel.

BACKGROUND: Mutations in the human ether-à-go-go-related gene (HERG) cause chromosome 7-linked long-QT syndrome (LQTS), an inherited disorder of cardiac repolarization that predisposes affected individuals to arrhythmia and sudden death. METHODS AND RESULTS: Here, we characterize the physiological consequences of 3 LQTS-associated missense mutations (V612L, T613M, and L615V) located in the pore helix of the HERG channel subunit. Mutant HERG subunits were heterologously expressed in Xenopus oocytes alone or in combination with wild-type HERG subunits. Two-microelectrode voltage-clamp techniques were used to record currents, and a single oocyte chemiluminescence assay was used to assay surface expression of epitope-tagged subunits. When expressed alone, V612L and T613M HERG subunits did not induce detectable currents, and L615V induced very small currents. Coexpression of mutant and wild-type HERG subunits caused a dominant-negative effect that varied for each mutation. CONCLUSIONS: These findings define the physiological consequences of mutations in HERG that cause LQTS and indicate the importance of the pore helix of HERG for normal channel function.

Animals↗
PubMed2001

Local cerebral glucose utilization decreases after heatstroke onset in rats.

The quantitative autoradiographic 2-[(14)C]-deoxy-D-glucose methods were used to assess the local cerebral glucose utilization (LCGU) in 46 brain structures in rats suffering from heatstroke. Heatstroke was induced by exposing the animals to an ambient temperature of 42 degrees C. The time at which the local cerebral blood flow (CBF) and mean arterial pressure (MAP) decreased from their peak levels was taken as the onset of heatstroke. Control rats were exposed to a temperature of 24 degrees C. The values of local CBF, MAP and means of total LCGU after heatstroke onset were all significantly lower than those in control rats. However, the values of colonic temperature were greater. Thus, it appears that the decreased cerebral metabolism and perfusion can be due to secondary effect of hypertension after heatstroke onset.

Animals↗
PubMed2001

Peptide mimetic HIV protease inhibitors are ligands for the orphan receptor SXR.

The orphan nuclear receptor SXR coordinately regulates drug clearance in response to a wide variety of xenobiotic compounds. This signaling system protects the body from exposure to toxic compounds; however, it can also pose a severe barrier to drug therapy. We now demonstrate that the human immunodeficiency virus (HIV) protease inhibitor ritonavir binds SXR and activates its target genes. This represents an example of a commonly used therapeutic agent that effectively activates SXR. We also show that other protease inhibitors are weaker (saquinavir) or unable to activate SXR (nelfinavir, indinavir) thus defining analogs that fail to induce SXR-regulated clearance pathways. Interestingly, HIV protease inhibitors are distinct from previously known SXR ligands in that they are peptide mimetic compounds. This expands the ligand specificity of SXR to include this unique chemical class whose pharmaceutical significance is expanding. Finally, we show that SXR ligands activate expression of multiple resistance protein 2, a critical regulator of bile flow and biliary drug excretion. These findings have important implications for the role of SXR in regulating drug clearance and hepatic disorders associated with impaired bile flow.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2001

[Unrelated donor allogenetic marrow transplantation in treatment of acute and chronic leukemia].

OBJECTIVE: To evaluate the clinical efficacy against acute and chronic leukemia of unrelated donor allogenetic marrow transplantation (URD-BMT) and to develop methods of preventing and treating complications of URD-BMT. METHODS: Eleven patients, 2 with acute lymphatic leukemia, 2 with acute myelocytic leukemia, and 7 with chronic myelocytic leukemia, were treated by URD-BMT. The median age of the 11 patients, 6 male and 5 females, were 26 years. The conditioning regimen for 10 patients was: BU 4 mg.kg(-1).d(-1) x 4 + CTX 60 mg.kg(-1).d(-1)1 x or TBI 7.5 Gy + CTX 60 mg.kg(-1).d(-1) x 2. Bone marrow with karyocytes in the dose of (2.6 approximately 4.8) x 10(8)/kg, including CD34+ cells in the dose of (3.82 approximately 12.8) x 10(6)/kg, and with the CFU-CM in the dose of (1.71 approximately 3.68) x 10(5)/kg, were transfused. Mycophenolate mofitil, cyclosporine, and methotrexate were given to prevent acute graft-versus-host disease (aGVHD). Continuous intravenous drip of heparin in low dose with Lipo protaglandin E1 was given to prevent hepatic veno-occlusive disease (VOD). Ganciclovir was used to prevent CMV infection. HLA phenotype was matched in 8 cases, mismatched in one locus in 2 cases, and mismatched in 2 loci in one case. RESULTS: Hematopoietic reconstruction was successful in all of the patients with the neutrophil count of 0.5 x 10(9)/L on the 10th day after transplantation and the platelet count of more than 20 x 10(9)/L on the 27(th) day. Analysis of DNA short series repeated sequence polymorphism showed the survival of bone marrow after transplantation in ten cases. One case of IV grade aGVHD, one case of II grade aGVHD, one case of serious VOD and III grade artrioventricular block, three cases of hemorrhagic cystitis, and one case of interstitial pneumonia occurred, the last case being died. Recurrence of leukemia occurred in one case seven months after the transplantation. That case was given the transfusion of donor's lymphocytes and has been so far under treated. Ten cases are alive in disease-free situation till now. CONCLUSION: URD-BMT is an effective method for the treatment of acute and chronic leukemia. The prophylaxis regimen against aGVHD, VOD, and CMV that we use is effective and safe.

Adolescent↗
PubMed2001

Gadolinium chloride-induced hepatocyte proliferation is prevented by antibodies to tumor necrosis factor alpha.

Gadolinium chloride (GdCl(3)) destroys large Kupffer cells and has been used extensively in mechanistic studies in a number of disease and toxicity processes; however, it cannot be used to study hepatocyte turnover since it increases cell proliferation itself. The mechanism by which GdCl(3) activates cell turnover in liver is unknown, but several possibilities exist. Here it was demonstrated that a direct mitogenic action on hepatocytes is unlikely since GdCl(3) did not stimulate the growth of primary rat hepatocyte in vitro. Therefore, it was hypothesized that GdCl(3) acts indirectly through mitogenic cytokines of nonparenchymal cell origin. Antibodies to tumor necrosis factor alpha (TNFalpha) were used to evaluate if TNFalpha is causally responsible for GdCl(3)-induced cell proliferation. GdCl(3) treatment of rats in vivo increased hepatocyte replication 5-fold in 24 h and 3-fold in 48 h. Pretreatment with specific anti-TNFalpha antibodies completely prevented these effects. However, when antibody treatment was delayed until 24 h after GdCl(3), increased cell proliferation was not prevented, suggesting that TNFalpha production during the first 24 h after treatment is responsible for activation of a signaling cascade involving other mitogens that sustain hepatocyte replication at 48 h. Twenty-four hours after treatment with GdCl(3), TNFalpha mRNA transcripts were increased 2-fold over control, an effect that was prevented by pretreatment with anti-TNFalpha antibody. NFkappaB, which is known to be involved in TNFalpha transcription, was activated by GdCl(3) about 4.5-fold over control 8 h after treatment in vivo, an increase not observed when antibodies to TNFalpha were present. When GdCl(3) was added to macrophages in culture, TNFalpha was nearly doubled 4 h after treatment. Additionally, conditioned media harvested from macrophages treated with GdCl(3) for 2 to 8 h stimulated the growth of HepG2 cells in culture about 2-fold, while antibodies to TNFalpha completely prevented this effect. Taken together, these data are consistent with the hypothesis that TNFalpha released from Kupffer cells at early time points prior to their destruction is causally responsible for triggering a cascade of events responsible for GdCl(3)-induced cell proliferation.

Animals↗
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↗