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Biomedical subjects

C W Lin

Publications and source records attributed to C W Lin.

At least 19 recordsLinked to original sources

Differential expression of human topoisomerase IIIalpha during the cell cycle progression in HL-60 leukemia cells and human peripheral blood lymphocytes.

Human topoisomerase IIIalpha (huTop IIIalpha) has been demonstrated to belong to type IA subfamily. In this study, we found that huTop IIIalpha expressed constitutively and remained at high levels throughout the cell cycle in HL-60 cells when compared to the cell-cycle-dependent expression of huTop IIIalpha in phytohemagglutinin-activated peripheral blood lymphocytes. During the cell cycle progression, this protein remained accentuated in the nucleolus without significant translocation from the nucleolus to the nucleoplasm. In addition, during the course of granulocytic maturation in DMSO-treated HL-60 cells, huTop IIIalpha levels decreased when cells stopped proliferation and nucleoli diminished in size. However, its level remained unchanged during the course of monocytic maturation of vitamin D(3)-treated HL-60 cells which still retained its proliferative capacity and did not change the size of the nucleolus. The data suggested that huTop IIIalpha is involved in rDNA metabolism, such as rDNA transcription. Its cellular level appeared to be under control during the cell cycle progression of normal lymphocytes, but was found to be deregulated in HL-60 cells which may be associated with the tumor transformed cell phenotypes.

Amino Acid Sequence↗

Expression of cyclin-dependent kinase 6 (cdk6) and frequent loss of CD44 in nasal-nasopharyngeal NK/T-cell lymphomas: comparison with CD56-negative peripheral T-cell lymphomas.

Lymphomas involving the nasal and nasopharyngeal region mainly include CD56-positive natural killer (NK)/T-cell lymphomas, CD56-negative peripheral T-cell lymphomas (PTL), and B-cell lymphomas. Among these, the CD56-positive lymphoma, presumably of an NK/T-cell nature, is frequently seen in Asian, Mexican, and South American patients. NK cells are proposed to be closer developmentally to T cells than to other lymphoid cells, because bipotential common progenitor cells of NK/T-cell lineage have been isolated. In this study, we collected 47 cases of nasal lymphoma and investigated the phenotypic difference between NK/T-cell lymphoma and PTL by examining the pattern of the developmentally differentially expressed molecules cdk6 (cyclin-dependent kinase 6), CD44, CD117, and by examining the rearrangement of the T-cell receptor gene (TcR-GR). cdk6, an essential regulator of the cell cycle in G1 progression, was over-expressed in a subset of cortical thymocytes, but absent in mature thymocytes. In contrast, CD44, a glycosylated adhesion molecule, was absent in cortical thymocytes, but present in mature thymocytes and peripheral activated T cells. We found both over-expression of nuclear cdk6 (n-cdk6) and frequent absence of CD44 in nasal CD56-positive NK/T-cell lymphomas, in contrast to most nasal CD56-negative PTL, which were CD44-immunoreactive with weak or no expression of n-cdk6. Almost all tested cases of NK/T-cell lymphoma displayed a germ-line configuration of TcR, without evidence of gene rearrangement. Thus, there seems to be a useful distinction between the classical NK/T type of nasal lymphoma (CD56+/n-cdk6+/CD44-/TcR-GR-) and PTL (CD56-/n-cdk6-/CD44+/TcR-GR+) involving the nasal region. The presence of Epstein-Barr virus does not seem to be a good marker for distinguishing between NK/T lymphoma and PTL involving the nasal region.

Adult↗

Genetic analysis and clinical evaluation of vacuolating cytotoxin gene A and cytotoxin-associated gene A in Taiwanese Helicobacter pylori isolates from peptic ulcer patients.

The aims of this study were to investigate the cytotoxin-associated gene A (cagA) and vacuolating cytotoxin gene A (vacA) subtype in Taiwanese H. pylori isolates from patients with gastroduodenal diseases and to assess the relationship between genotypes of isolates and clinical features. The vacA s1a allele was found in all isolates and vacA m1 allele was found in 15% of isolates. The cagA gene was found in 82.5% of isolates. The vacA s1a/m2 strains had a significantly higher prevalence rate than vacA s1a/m1 strains in Taiwan (p < 0.05). By aligning and comparing the nucleotide and amino acid sequences of vacA from the Taiwanese isolates, the signal sequence and N-terminal region were found to be highly conserved, but the middle region was found to be highly heterogeneous. Determining the relationship between the genotypes and clinical features, we found that the cagA gene was more closely associated with duodenal ulcer than with gastric ulcer and the vacA s1a/m2 strain was more closely associated with active chronic gastritis and atrophic gastritis than with chronic gastritis. Together, our results indicated that (i) the middle region of vacA gene in Taiwanese isolates was heterogeneous; (ii) s1a/m2 vacA strains had a high prevalence in Taiwanese peptic ulcers; and (iii) the cagA gene was significantly associated with duodenal ulcer.

Acute Disease↗

Cysteine modification of a putative pore residue in ClC-0: implication for the pore stoichiometry of ClC chloride channels.

The ClC channel family consists of chloride channels important for various physiological functions. Two members in this family, ClC-0 and ClC-1, share approximately 50-60% amino acid identity and show similar gating behaviors. Although they both contain two subunits, the number of pores present in the homodimeric channel is controversial. The double-barrel model proposed for ClC-0 was recently challenged by a one-pore model partly based on experiments with ClC-1 exploiting cysteine mutagenesis followed by modification with methanethiosulfonate (MTS) reagents. To investigate the pore stoichiometry of ClC-0 more rigorously, we applied a similar strategy of MTS modification in an inactivation-suppressed mutant (C212S) of ClC-0. Mutation of lysine 165 to cysteine (K165C) rendered the channel nonfunctional, but modification of the introduced cysteine by 2-aminoethyl MTS (MTSEA) recovered functional channels with altered properties of gating-permeation coupling. The fast gate of the MTSEA-modified K165C homodimer responded to external Cl(-) less effectively, so the P(o)-V curve was shifted to a more depolarized potential by approximately 45 mV. The K165C-K165 heterodimer showed double-barrel-like channel activity after MTSEA modification, with the fast-gating behaviors mimicking a combination of those of the mutant and the wild-type pore, as expected for the two-pore model. Without MTSEA modification, the heterodimer showed only one pore, and was easier to inactivate than the two-pore channel. These results showed that K165 is important for both the fast and slow gating of ClC-0. Therefore, the effects of MTS reagents on channel gating need to be carefully considered when interpreting the apparent modification rate.

Animals↗

Astrocytes modulate thapsigargin-induced changes in calcium concentration and neuronal survival.

When mature cerebellar granule neurons (CGN) grown in high K+ (25 mM K+, HK)-serum containing medium are subjected to the HK/serum deprivation, they are destined for neuronal death. In this study, we attempted to elucidate the roles of endoplasmic reticular (ER) Ca2+-store and co-cultured astrocytes in HK/serum deprivation induced neuronal death. Thapsigargin (TG), an inhibitor of ER Ca2+-ATPase was simultaneously applied with normal K+ (5 mM K+, NK) serum free medium, and its effects on neuronal death in either astrocyte-poor or astrocyterich culture were examined. By means of the fura-2 microfluorimetric technique, we monitored the changes of the intracellular Ca2+ concentration, [Ca2+]i, associated with neuronal death under various treatments. The results obtained showed that in astrocyte-poor cultures of mature CGN (10 days in vitro, DIV), the basal level of [Ca2+]i markedly decreased from 184 +/- 5 to 89.7 +/- 5 nM 24 h after HK/serum deprivation. Although treatment with TG slightly increased the [Ca2+]i to 117.6 +/- 4 nM, the survival rate of the neurons was even worse; it was reduced from 49 +/- 4% to 28 +/- 2%. In the astrocyte-rich cultures, HK/serum deprivation also caused a profound reduction of neuronal [Ca2+]i, from 166 +/- 3 to 90.2 +/- 6 nM, accompanied by even more serious neuronal death (95.5 +/- 1%). On the other hand, treatment with TG in astrocyterich cultures further lowered the [Ca2+]i to 65 +/- 2 nM but markedly improved the neuronal survival rate from 4.5 +/- 1% to 60 +/- 2% in a concentration-dependent manner. The strong implication of these findings is that ER Ca2+-store and astrocytes participate in modulating the responses of neurons to stress stimulation.

Animals↗

Immunolocalization of the keratinocyte growth factor in benign and neoplastic human prostate and its relation to androgen receptor.

BACKGROUND: Growth and development of the prostate are androgen-dependent. Keratinocyte growth factor (KGF), widely expressed by mesenchymal cells, is thought to act like an andromedin between stroma and epithelium of the prostate. Since KGF has recently emerged as an autocrine mediator in prostate cancer, we investigated the role KGF plays in the human prostate and its relationship to androgen receptor (AR). METHODS: Normal (n = 13), benign hyperplastic (n = 5), and neoplastic (n = 14) human prostate tissues as well as cultured epithelial and stromal cells were analyzed using polymerase chain reaction (PCR), Western blot analysis, and immunohistochemistry. RESULTS: Reverse transcriptase polymerase chain reaction and Western blotting showed KGF expression in stromal cultured cells of the normal prostate but not in epithelial cells. Using immunohistochemistry, KGF was found to be localized in fibroblasts and smooth muscle cells, independent of prostate disease. There was KGF expression in epithelial cells of BPH and prostate cancer. Human androgen receptor was uniformly expressed in the same secretory glandular cells that were positive for KGF in BPH and prostate cancer. CONCLUSIONS: Our results provide evidence that KGF is a stromal-derived mediator, recently shown to act in a paracrine manner in normal prostate but now detected in epithelial cells in prostate cancer and BPH. These findings support the hypothesis that KGF might act as an autocrine factor in prostate cancer and BPH.

Antibody Specificity↗

trans-2,6-,3,6- and 4,6-diaza-5,6,6a,7,8,12b-hexahydro-benzo[c]phenanthrene-10,11- diols as dopamine agonists.

The title compounds were synthesized by replacing the thiophene moiety of A-86929(2a) with variously substituted pyridines. Dopamine D-1 and D-2 binding and adenylate cyclase assays indicate that 4,6-diaza compounds 15 are potent and selective full D1 agonists when R1 is H or a small substituent and R2 = H, with D1 binding affinity and adenylate cyclase functional potency equivalent to that of A-86929(2a).

Dopamine Agonists↗

Roles of thapsigargin-sensitive Ca2+ stores in the survival of developing cultured neurons.

The roles of the intracellular calcium pool involved in regulating the Ca2+ profile and the neuronal survival rate during development were studied by using thapsigargin (TG), a specific inhibitor of endoplasmic reticulum (ER) Ca2+-ATPase in cultured cerebellar granule neurons. Measuring the neuronal [Ca2+]i directly in the culture medium, we found a bell-shaped curve for [Ca2+]i versus cultured days in cerebellar granule neurons maintained in medium containing serum and 25 mM K+. The progressive increase in [Ca2+]i of the immature granule neurons (1-4 days in vitro) was abolished by TG, which resulted in massive neuronal apoptosis. When the [K+] was lowered from 25 to 5 mM, neither the progressively increasing [Ca2+]i nor the survival of immature granule neurons was significantly changed over 24-h incubation. Similarly, TG caused a dramatic decrease in the [Ca2+]i and survival rate of these immature neurons when switched to 5 mM K+ medium. Following maturation, the granule neurons became less sensitive to TG for both [Ca2+]i and neuronal survival. However, TG can protect mature granule neurons from the detrimental effect of switching to a 5 mM K+ serum-free medium by decreasing [Ca2+]i to an even lower level than in the respective TG-free group. Based on these findings, we propose that during the immature stage, TG-sensitive ER Ca2+-ATPase plays a pivotal role in the progressive increase of [Ca2+]i, which is essential for the growth and maturation of cultured granule neurons.

Animals↗

Endemic burkholderia cepacia bacteraemia: clinical features and antimicrobial susceptibilities of isolates.

Burkholderia cepacia has emerged as a nosocomial pathogen, causing numerous outbreaks, particularly among cystic fibrosis (CF) patients. Reports of clinical features of endemic B. cepacia bacteraemia in non-CF patients are rare. Twenty-five patients with B. cepacia bacteraemia were matched with 25 controls with nosocomial Escherichia coli bacteraemia at China Medical College Hospital, Taichung, Taiwan, over a period of 3 y. Case-patients included 16 men and 9 women, from 13 to 75 y. All had severe underlying diseases, most commonly malignancy (44%). Twenty-four patients (96%) had nosocomial infections. Five patients (20%) had polymicrobial bacteraemia. Our controls included 11 men and 14 women, age range 18-80 y. The most common underlying disease was malignancy (44%). Multivariate analysis revealed that indwelling central venous catheter was the significant risk factor predisposing to B. cepacia bacteraemia (p= 0.025). Eleven case-patients met the definition of catheter-related bloodstream infection. Fifteen patients (60%) received appropriate antimicrobial therapy after notification of positive blood cultures and susceptibility patterns. The overall case-fatality rate was 12% (3/25), only 1 of whom died of B. cepacia bacteraemia. There was no statistically significant difference in overall mortality rate between case-patients and controls. All isolates were susceptible to ceftazidime, piperacillin and minocycline and 84% of the isolates were susceptible to imipenem. B. cepacia should be considered a potential pathogen in hospitalized patients with severe underlying diseases, particularly those with indwelling central venous catheters.

Adolescent↗

Elimination of the slow gating of ClC-0 chloride channel by a point mutation.

The inactivation of the ClC-0 chloride channel is very temperature sensitive and is greatly facilitated by the binding of a zinc ion (Zn2+) from the extracellular side, leading to a Zn2+-induced current inhibition. To further explore the relation of Zn2+ inhibition and the ClC-0 inactivation, we mutated all 12 cysteine amino acids in the channel and assayed the effect of Zn2+ on these mutants. With this approach, we found that C212 appears to be important for the sensitivity of the Zn2+ inhibition. Upon mutating C212 to serine or alanine, the inactivation of the channel in macroscopic current recordings disappears and the channel does not show detectable inactivation events at the single-channel level. At the same time, the channel's sensitivity to Zn2+ inhibition is also greatly reduced. The other two cysteine mutants, C213G and C480S, as well as a previously identified mutant, S123T, also affect the inactivation of the channel to some degree, but the temperature-dependent inactivation process is still present, likewise the high sensitivity of the Zn2+ inhibition. These results further support the assertion that the inhibition of Zn2+ on ClC-0 is indeed due to an effect on the inactivation of the channel. The absence of inactivation in C212S mutants may provide a better defined system to study the fast gating and the ion permeation of ClC-0.

Amino Acid Sequence↗

De novo CD5+ Burkitt lymphoma/leukemia.

CD5 is a T-cell marker aberrantly expressed in B-cell chronic lymphocytic leukemia and mantle cell lymphoma. Other B-cell neoplasms, including Burkitt lymphoma, are usually CD5-. We report 4 cases of de novo CD5+ Burkitt lymphoma/leukemia in elderly patients, all of whom were in a leukemic phase and had variable lymph node and splenic involvement. The blasts were typically medium sized, with folded nuclei, distinct but not prominent nucleoli, and moderate amounts of somewhat vacuolated basophilic cytoplasm; they were terminal deoxynucleotidyl transferase--negative and surface immunoglobulin--positive. All 4 cases demonstrated c-myc rearrangement, but none had t(14;18), t(11;14), or cyclin D1 overexpression or rearrangement. Only 1 patient achieved complete remission after hyper-CVAD (hyperfractionated cyclophosphamide, vincristine, doxorubicin, dexamethasone) therapy. One patient responded poorly to hyper-CVAD, and 2 patients died during induction chemotherapy. These rare cases of aggressive lymphoid malignancy with CD5 positivity and molecular features associated with Burkitt lymphoma/leukemia are best classified as Burkitt leukemia. However, the morphologic and immunophenotypic similarity to the blastoid variant of mantle cell lymphoma are diagnostically challenging. The diseases can be distinguished at the genetic level, since Burkitt lymphoma involves the rearrangement of c-myc, and mantle cell lymphoma usually the overexpression or rearrangement of cyclin D1.

Aged↗

Identification of an activin-follistatin growth modulatory system in the human prostate: secretion and biological activity in primary cultures of prostatic epithelial cells.

PURPOSE: To determine if the activin/follistatin system is present in human prostate tissue and primary cultures of prostatic epithelium and if these growth factors play a role in the control of epithelial cell growth. MATERIALS AND METHODS: Cells derived directly from human prostates were studied to determine: a) if they secrete activin and follistatin, and b) if they are growth inhibited by activin. Primary cell cultures were established from tissues removed from 13 unselected prostate carcinoma patients in order to examine the secretion of activin and follistatin and test the effects of these proteins on cell proliferation. RESULTS: Both primary explant cells and epithelial cells isolated and sub-cultured from explant cultures secreted activin A and follistatin. Treatment of cultured cells with recombinant human activin A resulted in a dose-dependent inhibition of thymidine incorporation, with an IC50 of 0.22 nM. Recombinant follistatin neutralized the inhibitory effects of activin A on cell proliferation whilst adding follistatin alone enhanced thymidine incorporation, suggesting a similar neutralizing effect on the endogenous activin produced by these cells. CONCLUSION: These results demonstrate that cells derived from human prostate tissue secrete activin and follistatin and, as observed in human prostate cancer cell lines, activin inhibited the growth of prostatic epithelial cells. Also consistent with our earlier studies of prostate cancer cell lines, the biological activity of activin was neutralized by follistatin. These observations support the hypothesis that the activin/follistatin system plays an important role in the local regulation of human prostate cell growth.

Activins↗

Pulse oximeter-associated toe injuries in a premature neonate: a case report.

Pulse oximetry is noninvasive and widely used in the intensive care unit and during surgery. Complications associated with the use of pulse oximetry have been reported, including burns, pressure erosion, skin necrosis and digital sensory loss. The causes of these complications may be due to the incompatibilities between the probes and the monitors used from different companies, pressure duration for too long on a single skin site or overheating induced by a short circuit of the probe cable. We report a 940-g premature infant who had severe pulse oximetry-associated injury to the oximetry site. This may have been due to the infant's susceptibility to injury resulting from his critical condition, including low cardiac output, poor peripheral circulation and poor heat dissemination. Our experience shows that, when pulse oximetry is used, especially in critically ill, premature infants, frequent checking of the sensor and the site where the sensor is applied is required to avoid burn injury or pressure erosion of the skin.

Burns↗

Altered intracellular calcium level in association with neuronal death induced by lithium chloride.

In this study, we examined the effects of lithium chloride (LiCl) on the intracellular calcium levels ([Ca2+]i), and the survival of immature and mature cultured cerebellar granule neurons (CGNs) grown in medium containing high (25 mmol/L) or normal (5 mmol/L) potassium (K+) levels. LiCl dramatically reduced [Ca2+]i in immature CGNs maintained in high K+ (HK) medium and in those switched to serum containing normal K+ (NK) medium for 1 to 2 days. This reduction in [Ca2+]i led to massive neuronal death of immature neurons developed in both HK and NK medium. In mature (cultured 5-8 days in vitro) CGNs, LiCl exhibited potent toxicity when cells were grown in HK medium, and led to increased [Ca2+]i. Exposing mature CGNs to serum deprivation and normal extracellular K+ concentrations decreased [Ca2+]i and induced cell death, while the addition of LiCl in these conditions further decreased [Ca2+]i but prevented cell death. The morphologic features revealed by Nomarski optics further confirmed these effects of LiCl on neuronal survival. Together, these findings indicate that the effects of LiCl on [Ca2+]i and neuronal death, and the association between [Ca2+]i and cell death, depend on the developmental stage of CGNs and the growth conditions to which they are subjected. These findings may help in understanding the mechanism of neurotoxicity of LiCl during therapy.

Animals↗

Identification and expression of the Na+/H+ exchanger in mammalian cerebrovascular and choroidal tissues: characterization by amiloride-sensitive [3H]MIA binding and RT-PCR analysis.

We report the initial characterization of [3H]5-(N-methyl-N-isobutyl)amiloride (MIA) binding to the Na+/H+ exchanger (NHE) and expression of its gene in mammalian cerebrovascular, choroidal and neocortical tissues. [3H]MIA bound reversibly to particulate fractions of rat, pig and human cerebral microvessels, choroid plexus and cerebral cortex. Scatchard analyses revealed binding to a single amiloride-sensitive site with dissociation constants (Kd) ranging from 20 to 90 nM for the various tissue preparations. The maximal binding capacities (Bmax) were between 2 to 17 pmol/mg protein and were several-fold greater in cerebral microvessels compared to the cerebral cortex. Amiloride, MIA, 5-(N, N-hexamethylene)amiloride (HMA), 5-(N, N-dimethyl)amiloride (DMA) and 5-(N-methyl-N-isopropyl)amiloride (IPA) variably displaced [3H]MIA binding to the microvessels in the following rank order: MIA>HMA>/=IPA>DMA>amiloride. Benzamil, a potent ligand of the Na+/Ca+ transporter was the least sensitive. These binding results were most compatible with the existence of the amiloride-sensitive NHE type 1 in the brain vascular and choroidal tissues. To substantiate this, we utilized reverse transcription polymerase chain reaction (RT-PCR) techniques to search for NHE-1 mRNA. Using primers corresponding to conserved sequences of the human growth factor-activatable NHE gene, RT-PCR revealed strong expression of NHE-1 mRNA in cerebral microvessels, choroid plexus, pial vessels and vascular smooth muscle cells relative to neocortical tissues from several species including rat, pig, cow, monkey and human subjects. Further confirmation of NHE-1 isoform mRNA expression in the cerebrovascular tissues was obtained by HpaII restriction digestion analysis and by subcloning and sequencing of the PCR amplified products. Our study suggests that mammalian cerebrovascular and choroidal tissues contain high amounts of the ubiquitous amiloride-sensitive [3H]MIA binding proteins consistent with the expression of NHE type 1 mRNA.

Amiloride↗

Induced expression of neuronal membrane attack complex and cell death by Alzheimer's beta-amyloid peptide.

beta-amyloid peptide (A beta) and complement-derived membrane attack complex (MAC) are co-localized in senile plaques of brains from Alzheimer's disease (AD) patients. But the relationship between A beta and complement activation is unclear. We have used human neurotypic cells, differentiated SH-SY5Y, as a model system to examine regulation of neuronal MAC expression and cell death by A beta. We demonstrated that mRNAs (C1q, C2, C3, C4, C5, C6, C7, C8 and C9) and proteins (C1q, C3 and C9) for the major components of the classical complement cascade are present in the SH-SY5Y neurotypic cells, indicating that neuronal cells can synthesize the necessary proteins required for MAC formation. Furthermore, immunocytochemical studies showed the A beta-induced neuronal MAC expression on the SH-SY5Y cells after CD59 was removed by PIPLC or blocked by anti-CD59 antibody. Meanwhile, increased A beta-induced neuronal cell death was observed following treatment with anti-CD59. Taken together, these results suggest that A beta activates neuronal complement cascade to induce MAC, and a deficiency of endogenous complement regulatory proteins, e.g., CD59, may increase the vulnerability of neurons to complement-mediated cytotoxicity.

Alzheimer Disease↗

Androgen responsiveness of stromal cells of the human prostate: regulation of cell proliferation and keratinocyte growth factor by androgen.

PURPOSE: Growth and development of the prostate are androgen dependent and mainly influenced by stromal-epithelial interaction. It is believed that indirect androgenic activation of paracrine factors like keratinocyte growth factor (KGF) in the prostatic stroma influences the growth of epithelial cells. In this study we investigated the role androgen plays in stromal cell growth and stimulation of KGF in the human prostate. MATERIALS AND METHODS: Stromal cells were derived from explant primary culture of human normal or benign prostatic tissue. The effect of different dihydrotestosterone (DHT) concentrations on cell proliferation was measured using 3[H]thymidine incorporation assay. The effect of DHT on levels of KGF protein was determined by Western blotting. The effect of DHT on levels of KGF gene expression was measured by various cycles of polymerase-chain-reaction (PCR) and multiplex PCR. RESULTS: Characterization of stromal cells showed epithelial cells less than 9.5% in all passages. DHT stimulated human prostate stromal cells in a dose dependent fashion over a concentration range of 0.001-10 nM. Immunocytochemical evaluation of KGF after DHT exposure showed a higher staining intensity. Relative quantitation of Western blotting showed a 1.93-fold increase in KGF protein in the androgen treated stromal cells. At 1 nM DHT conventional and multiplex PCR revealed a significant stimulation of the KGF mRNA expression. CONCLUSIONS: These data show for the first time that androgen stimulates cell proliferation as well as KGF protein and gene expression in human prostate stromal cells. This supports the hypothesis that androgen-induced stromal-derived KGF stimulates prostate epithelial cell growth.

Aged↗