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Biomedical subjects

Y S Lin

Publications and source records attributed to Y S Lin.

At least 55 records · Page 3Linked to original sources
PubMed2000

Antagonism between members of the CNC-bZIP family and the immediate-early protein IE2 of human cytomegalovirus.

The HCMV IE2 protein negatively autoregulates its own expression as well as represses the transactivation activity of p53. Using the repression domain of IE2 as bait in the yeast two-hybrid system, Nrf1 and Nrf2, members of the CNC-bZIP family, were found to be IE2-interacting proteins. Residues 331-448 encompassing the DNA-binding and the dimerization domains of Nrf1 are sufficient for the interaction. The interaction was further confirmed in vitro by a glutathione S-transferase pull-down assay and in vivo by co-immunoprecipitation. In transient transfection studies, transcription driven by six copies of an NF-E2 site or by chimeric proteins between the DNA-binding domain of LexA and members of the CNC-bZIP family is repressed by IE2. Importantly, the DNA binding activity of the Nrf1/MafK heterodimer is not impeded by IE2. In a parallel study, CNC-bZIP factors attenuate the negative autoregulation of IE2. The attenuation could be explained by the finding that Nrf1 functions alone and synergistically with its heterodimerization partner, MafK, in inhibiting the DNA binding activity of IE2. Taken together, these results demonstrate the existence of antagonism between members of the CNC-bZIP family and IE2.

Cell Line↗
PubMed2000

In vivo staphylococcal enterotoxin B (SEB)-primed murine splenocytes secrete mediators which suppress CD25(hi) expression and cell cycle progression of naive splenocytes in response to SEB in vitro.

Administration of bacterial superantigen results in clonal activation of T cells followed by a state of hyporesponsiveness to subsequent antigen stimulation. Using a coculture system, we showed that the splenocytes from staphylococcal enterotoxin B (SEB)-injected BALB/c mice suppressed the proliferative response of naive splenocytes to SEB stimulation. The suppressive effect also occurred in Fas-deficient MRL-lpr/lpr mice. When naive responder cells were separated by a semipermeable membrane from SEB-primed effector cells, the suppressive effect remained apparent. The hyporesponsiveness of responder cells did not result from excessive induction of apoptosis, but rather from prevention of entering the S and G2/M phases of the cell cycle. The IL-2 levels in culture supernatants were low with the presence of SEB-primed effector cells. However, addition of IL-2 to the cocultures only partially reversed the inhibitory effect. Further studies revealed a reduced level of the CD25(hi) subpopulation in responder cells when cultured in the transwell with the presence of SEB-primed effector cells compared to that with saline-primed controls. This inhibitory effect was not observed for SEB-induced activation of CD25(int) and CD69 expression. Taken together, using a transwell culture system, we show in this study an inhibition of CD25(hi) expression and cell cycle arrest in target cells, which may serve at least in part the mechanisms of SEB-induced hyporesponsiveness.

Animals↗
PubMed2000

Acute neurogenic airway plasma exudation and edema induced by inhaled wood smoke in guinea pigs: role of tachykinins and hydroxyl radical.

We studied the mechanisms underlying the wood smoke-induced acute airway injury in 120 anaesthetized guinea pigs. Five minutes after airway exposure, various doses of wood smoke produced a dose-dependent increase in Evans blue dye contents at all airway levels measured. Additionally, inhaled wood smoke produced submucosal edema of the trachea and bronchus, and peribronchial edema. These acute airway responses were nearly abolished by pretreatment with CP-96,345 alone [a tachykinin NK(1) receptor antagonist; (2S, 3S)-cis-2-(diphenylmethyl)-N-((2-methoxyphenyl)-methyl)-1-azabicyc lo( 2.2.2.)-octan-3-amine] or with a combination of CP-96,345 and dimethylthiourea (a hydroxyl radical scavenger), and were attenuated by pretreatment with dimethylthiourea alone, yet were not affected by pretreatment with SR-48,968 [a tachykinin NK(2) receptor antagonist; (S)-N-methyl-N(4-(4-acetylamino-4-phenylpiperidino)-2-(3, 4-dichlorophenyl)-butyl)benzamide], with a combination of CP-96,344 and SR-48,965 (inactive enantiomers), with MK-886 [a leukotriene biosynthesis inhibitor; L-663, 536(3-(1-(4-chlorobenzyl)-3-t-butyl-thio-5-isopropylindol-2-yl)-2, 2-dimethylpropanoic acid], with indomethacin (a cyclooxygenase inhibitor), or with N(G)-nitro-L-arginine methyl ester (a nitric oxide (NO) synthase inhibitor). The activity of airway neutral endopeptidase (an enzyme for tachykinin degradation) was not influenced by wood smoke at 5-min post-exposure. We conclude that both endogenous tachykinins and hydroxyl radical play an important role in producing smoke-induced acute airway plasma exudation and airway edema in guinea pigs. The contribution of tachykinins to these neurogenic responses is mediated via the activation of tachykinin NK(1) receptors and partly via a hydroxyl radical mechanism, and is not associated with inactivation of neutral endopeptidase.

Animals↗
PubMed2000

Laryngeal C-fiber afferents are not involved in the apneic response to laryngeal wood smoke in anesthetized rats.

Laryngeal exposure to wood smoke in rats evokes a reflex apnea which is mediated through superior laryngeal afferents (J. Appl. Physiol. 83: 723-730, 1997). To study the role of laryngeal C-fiber afferents in eliciting this response, capsaicin aerosol (0.05 - 0.2 microg/ml) and 5 ml of wood smoke were delivered separately into a functionally isolated larynx of anesthetized Sprague-Dawley rats at a constant flow rate of 1.4 ml/s, while animals breathed spontaneously. Studies were repeated after either an intravenous injection of ruthenium red (2 mg/kg; n = 8), a perineural capsaicin treatment (200 microg/ml for 5 min; n = 8) of the superior laryngeal nerves, or a perineural sham treatment (n = 8); Ruthenium red inhibits the stimulation of afferent C-fiber nerve endings by capsaicin, whereas perineural capsaicin treatment selective blocks the conduction of C-fiber afferents. Either ruthenium red or perineural capsaicin treatment abolished the apneic response to laryngeal capsaicin, but did not significantly affect the apneic response to laryngeal wood smoke. Furthermore, the apneic responses to both types of irritants were not significantly altered by perineural sham treatment, yet were completely eliminated by a subsequent denervation of superior laryngeal nerves. Our results suggest that superior laryngeal C-fiber afferents are not involved in eliciting the reflex apneic response to laryngeal wood smoke in anesthetized rats. It is speculated that this response may result mainly from the stimulation of myelinated afferents, possibly laryngeal irritant receptors.

Aerosols↗
PubMed2000

Intra-striatal infusion of D-amphetamine induces hydroxyl radical formation: inhibition by MK-801 pretreatment.

Recent evidence suggests that free radicals can be produced in the brain following systemic administration of repeated or high doses of D-amphetamine (AMPH). However, it has been proposed that the toxic effects of AMPH are mostly secondary to AMPH-induced hyperthermia, and agents that protect against AMPH neurotoxicity do so by blocking AMPH-induced hyperthermia or causing hypothermia. In this study, we examined the effects of AMPH on the formation of hydroxyl radicals (*OH) following its infusion into the rat striatum via a microdialysis probe. We found that intra-striatal perfusion of AMPH (10 microM) caused an increased formation of hydroxyl radicals but did not raise the core temperatures of the rats. Pretreatment with the NMDA antagonist MK-801 (0.5 mg/kg) attenuated hydroxyl radical production elicited by AMPH infusion, although core body temperatures in AMPH-treated rats were not significantly altered. Additionally, infusion of AMPH in the striatum increased extracellular dopamine concentration and this effect was potentiated by MK-801 pretreatment. Thus, these results demonstrate that direct infusion of AMPH in the striatum induces hydroxyl radical production without causing hyperthermia, and also imply that activation of glutamate NMDA receptors mediates, at least in part, AMPH-induced hydroxyl radical formation in the rat striatum.

Animals↗
PubMed2000

Infection of five human liver cell lines by dengue-2 virus.

Elevated serum transaminase levels of dengue patients indicate the possible impact of dengue virus infection on liver function. To elucidate the action of dengue virus infection in liver cells, an in vitro cell line system was established that mimicked the liver status of diverse clinical patients. Briefly, four hepatoma cell lines (HA22T, Huh7, Hep3B, and PLC) and one nonmalignant hepatocyte cell line (Chang liver) were included, representing various levels of tumorigenicity and differentiation. Our data showed that in these five cell lines, dengue-2 virus attached to each cell type equally well; however, this virus had higher replication rates and levels of virion production in differentiated Huh7, PLC, Hep3B, and Chang liver cells. Likewise, a lower replication rate was observed in the de-differentiated HA22T cells. Differentiation-related factors seem to play an important role in dengue virus replication. Further study showed that sodium butyrate (NaB, a differentiation inducer) treatment enhanced dengue virus replication in HA22T cells. Moreover, we found that the severity of morphologic aberration and the increase in aspartate aminotransferase (AST) levels correlated with the virus replication rate in the four infected hepatoma cells. In conclusion, we showed that dengue virus can infect diverse liver cells with differing replication efficiency, which causes cytopathic effects (CPEs) of diverse severity. Among the CPEs, the increased AST levels correlated with the clinical results from 24 dengue fever patients, who showed increased AST levels at the onset of fever. In summary, we find that dengue-2 virus replicates actively and causes severe CPEs in differentiated hepatoma cells. Factors related to differentiation as well as tumorigenicity seem to play critical roles, though the mechanisms of action remain unclear.

Adolescent↗
PubMed2000

Detection of tumor cells in leukapheresis products from patients with breast cancer using immunocytochemical staining method.

We used a combination of 4 monoclonal antibodies (BM7, BM8 against MUC1, 5D3 against CK8,18,19 and HEA125 against human epithelial antigen) and a sensitive immunocytochemical staining using cytospin preparation to identify breast tumor cells in leukapheresis products (LP). This assay allowed detection of one tumor cell in 1x10(6) mononuclear cells (MC). In clinical specimens, tumor cells were detected in LP from 6 of 42 (14.3%) patients in the adjuvant treatment group, from 2 of 11 (18.2%) patients in the neoadjuvant treatment group and from 9 of 43 (20.1%) in the group of patients with metastatic disease. Tumor cell counts ranged from 0.25-5 cells in 1x10(6) normal cells per LP. The median tumor cell concentration was higher in specimens from patients with metastatic disease (median=0.96) than in specimens from patients in the adjuvant and neoadjuvant treatment groups (median=0.5 and 0.75). No significant differences between the epithelial cell positive group and the epithelial cell negative group with respect to tumor size, lymph nodes involvement, tumor grade, histological type and receptor were found. We conclude that immunocytochemical staining of cytospin preparation is a sensitive and simple method to detect and quantitate breast cancer cells in LP.

Adult↗
PubMed2000

Sensitive detection of micrometastases in bone marrow from patients with breast cancer using immunomagnetic isolation of tumor cells in combination with reverse transcriptase/polymerase chain reaction for cytokeratin-19.

We report a highly sensitive method to detect rare human breast cancer cells, which combines an immunomagnetic separation (IMS) using antibody BM2 against MUC-1 with cytokeratin-19 (CK19) and the reverse transcriptase/polymerase chain reaction (RT-PCR). The IMS-RT-PCR technique allows the detection of 1 tumor cell/10(7)-10(8) mononuclear cells. This is at least ten times more sensitive than CK19 RT-PCR alone, or immunocytochemistry. All 117 peripheral blood and 8 bone marrow samples obtained from healthy donors as negative controls were positive for beta2-microglobulin by RT-PCR but negative for CK19 by IMS-RT-PCR or RT-PCR alone. Out of 26 bone marrow samples from breast cancer patients, 18 had CK19 transcripts detectable by IMS-RT-PCR. In contrast, only 14 and 13 samples from the 26 were found to be positive by RT-PCR alone or by routine immunocytochemical staining. In conclusion, IMS-RT-PCR for CK19 is a highly sensitive and specific method for detecting very low numbers of micrometastatic breast cancer cells in bone marrow amidst an excess of nonmalignant cells. For the early diagnosis of disseminating disease, this assay is more efficient than RT-PCR alone and routine immunocytochemistry.

Bone Marrow↗
PubMed2000

Diagnosis of MRSA with neural networks and logistic regression approach.

Antibiotic-resistant pathogens are increasingly prevalent in the hospitals and community. A timely and accurate diagnosis of the infection would greatly help physicians effectively treat patients. In this research we investigate the potential of using neural networks (NN) and logistic regression (LR) approach in diagnosing methicillin-resistant Staphylococcus aureus (MRSA). Receiver-Operating Characteristic (ROC) curve and the cross-validation method are used to compare the performances of both systems. We found that NN is better than the logistic regression approach, in terms of both the discriminatory power and the robustness. With modeling flexibility inherent in its techniques, NN is effective in dealing with MRSA and other classification problems involving large numbers of variables and interaction complexity. On the other hand, logistic regression in our case is slightly inferior, offers more clarity and less perplexity. It could be a method of choice when fewer variables are involved and/or justification of the results is desired.

Decision Support Techniques↗
PubMed2000

Competition with TATA box-binding protein for binding to the TATA box implicated in human cytomegalovirus IE2-mediated transcriptional repression of cellular promoters.

The human cytomegalovirus IE2 is a sequence-specific DNA-binding protein. A consensus IE2-binding site (IBS) contains two copies of the dinucleotide CG separated by 10 not well-conserved but AT-rich nucleotides. In this report, we demonstrated that the TATA box of the insulin-like growth factor binding protein 4 (IGFBP4) promoter is embedded in an IBS. In a transient transfection study, IE2-mediated repression of a reporter driven either by a synthetic promoter containing the IGFBP4 TATA/IBS element or by the native IGFBP4 promoter was dependent on the intactness of the IBS. Competition with TBP for binding to the IGFBP4 TATA/IBS element may underlie the mechanism for the IE2-mediated repression, because IE2 and TATA box-binding protein (TBP) binding to the IGFBP4 TATA/IBS element are mutually elusive. Moreover, the TATA boxes of several other genes, including ADA and CPH-70, are likewise confined in IBS-like sequences. The IE2 interacts with those TATA/IBS elements in vitro and inhibits transcription driven by them in vivo, supporting the idea that competitive inhibition of TBP binding to the TATA box represents a novel mechanism exploited by IE2 to repress cellular gene expression.

Binding Sites↗
PubMed2000

Depressive mood and suicide among middle-aged workers: findings from a prospective cohort study in Nagoya, Japan.

BACKGROUND: In Japan, mortality from suicide has peaked around 50 years old among men, with increasing trend after 65 years old, and this peak became more apparent in recent years. Beside this, "psychological autopsy" has revealed depression as one of the most important risk factors for suicide. There is, however, no cohort study which examined the relationship between depressive mood measured by simple method and suicide in middle-aged general population. METHODS: In 1989, baseline information was collected by a self-administered questionnaire, and 18,450 workers were followed up to March 31, 1995. All deaths observed during active service were identified, and when retired, its date was recorded. Among 5,352 male workers aged between 40 to 54, 11 committed suicide during follow-up period of 5 years. Analysis were carried out by Cox's proportional hazard model, controlling for age. RESULTS: Those who slept 9 hours or more per night demonstrated 12.14-fold risk of suicide compared with those who slept less than 9 hours. Smokers were more likely to commit suicide than non-smokers. Those who answered affirmatively to more than 7 out of 12 questions, which were derived from Zung self-rating depression scale, experienced an increased risk of suicide (RR 9.95; 95%CI: 1.89-52.44), even after adjusting for other confounding factors. CONCLUSION: We found an association between depressive mood and subsequent suicide in a middle-aged workers. Detailed observation and follow-up of those with depressive mood should be systematically organized with due attention and caution.

Adult↗
PubMed2000

Sensitive and specific detection of carcinoembryonic antigen cDNA using the hot start polymerase chain reaction technique.

This study evaluated the specificity and sensitivity of hot start polymerase chain reaction (RT-PCR) for identification of carcinoembryonic antigen (CEA) cDNA. Hot Start Storage and Reaction Tubes provide a simple mechanism for synchronizing hot start amplifications without the need for manual intervention. A wax barrier uses a layer of solid wax to separate the retained reagents and the test sample from the bulk of the reagents until the first heating step of automated thermal cycling melts the wax and convectively mixes the two aqueous layers. Wax-mediated hot start PCR greatly increases the specificity and sensitivity of amplifying CEA cDNA. 12 out of 12 samples were positive for CEA cDNA from 10 CEA mRNA positive tumor cells in 10(7) normal cells by hot start CEA-PCR, and 8 out of these samples were positive for CEA cDNA by CEA-PCR without hot start. The hot start PCR showed the single specific product band, but PCR without hot start showed the specific product band and the other non-specific product band. We conclude that the hot start PCR technique could sensitively and specifically detect CEA cDNA after reverse transcription of CEA mRNA and minimize primer dimers by amplification.

Breast Neoplasms↗
PubMed2000

[The study and manufacture of multifunctional brain microsurgery operation dilator].

The dilator consists of fixative clasp-handle, fixative platform, support arm, spatula and handle. The dilator may be fixed on the edge of bone window easily in the brain operation. The functions of the dilator include localization, dilation, expose, washing, lighting and suction. The spatula of the dilator may be prepared according to the different depth and width of the operation field.

Brain↗
PubMed1999

Characterization of ADP-glucose pyrophosphorylase from Rhodobacter sphaeroides 2.4.1: evidence for the involvement of arginine in allosteric regulation.

ADP-glucose pyrophosphorylase (ADPGlc PPase, EC 2.7.7.27) from Rhodobacter sphaeroides 2.4.1 has been purified to near homogeneity. The enzyme reacted in Western blots to polyclonal antibodies raised against other bacterial ADPGlc PPases. The purified enzyme was found to be activated by fructose 6-phosphate, fructose 1,6-bisphosphate, and pyruvate and inhibited by phosphate, phosphoenolpyruvate, ADP, and pyridoxal phosphate. Kinetic studies indicate that AMP, while having little effect on kinetic parameters at pH 8 in the absence of effectors, is a specific ligand for an allosteric site(s). Treatment of the purified enzyme with the arginyl reagents 2,3-butanedione and phenylglyoxal resulted in desensitization of the enzyme to both activation and inhibition by metabolites. Phosphate, fructose 6-phosphate, and AMP were found to protect the enzyme against allosteric desensitization supportive of these metabolites interacting at common site(s) or with a common enzyme form. As a first step in cloning the gene coding for this enzyme, a polymerase chain reaction fragment was generated from genomic DNA using primers based on amino terminal sequencing data and a highly conserved region in known ADPGlc PPases. The sequence of this fragment and position of amino terminal arginines in comparison to other known ADPGlc PPases is discussed in relation to the kinetic and chemical modification data.

Allosteric Regulation↗
PubMed1999

Bad overexpression sensitizes NIH/3T3 cells to undergo apoptosis which involves caspase activation and ERK inactivation.

The effect of Bad overexpression on apoptosis was demonstrated by a mouse Bad transgene stably expressed in NIH/3T3 cells. The cells overexpressing Bad treated with either serum starvation or ceramide showed apoptotic characteristics evident at 18 and 8 h, respectively. Whether serum deprivation and ceramide utilize a common death pathway requires further investigation. The time for the first apoptosis detection was shortened to 2 h and was prominent at 4 h, while above that time cells were maintained under serum-depleted conditions in the presence of ceramide (40 microM). Further investigation revealed that the activity of caspase-3 (CPP32) was elevated after ceramide treatment in Bad-transfected cells compared to that of the cells without Bad transfection, indicating the involvement of caspase cascade. Furthermore, the Bad-transfected cells showed reduced phosphorylation of extracellular signal-regulated kinase (ERK). Taken together, we hypothesize that Bad-overexpressing NIH/3T3 cells in the presence of ceramide undergo apoptosis by activating caspase cascade. Simultaneously, the cell survival pathway was blocked possibly by inactivation of the MAPK pathway such as the down-regulation of ERK.

3T3 Cells↗
PubMed1999

Neonatal capsaicin treatment alters immediate ventilatory responses to inhaled wood smoke in rats.

Neonatal capsaicin treatment chronically ablates unmyelinated C fibers, yet also destroys a small amount of myelinated fibers. Inhalation of wood smoke evokes respiratory reflexes resulting from stimulation of both lung C-fiber nerve endings (unmyelinated afferents) and irritant receptors (myelinated afferents). This study investigated the influences of neonatal capsaicin treatment on the immediate ventilatory responses to inhaled wood smoke in adult rats. Inhalation of wood smoke (approximately 6 ml) via a tracheostomy immediately triggered only an augmented inspiration in 16 rats neonatally treated with capsaicin (50 mg/kg, subcutaneous injection). In contrast, inhaled wood smoke evoked a slowing of respiration in 11 neonatal vehicle-treated rats and an augmented inspiration in another five. The inability to exhibit the slowing of respiration and the persistence of the augmented inspiration in capsaicin-treated rats are consistent with our hypothesis that these two reflex responses originate from stimulation of lung vagal C-fiber afferents and irritant receptors, respectively. Since all capsaicin-treated rats responded to smoke with an augmented inspiration, it is further suggested that neonatal capsaicin treatment selectively impairs the reflex functions of C-fiber afferents and well preserves the reflex functions of lung irritant receptors.

Animals↗
PubMed1999

Antagonism of p53-dependent apoptosis by mitogen signals.

p53-mediated apoptosis is antagonized by growth factor stimulation. Here, we show that p53-dependent cell death induced by DNA damage was effectively prevented by mitogen activation. The levels of Bcl-2, Bcl-xL, and Bax were not altered by cisplatin treatment and mitogen rescue. Instead, the protection against p53-regulated apoptosis was mediated by at least three distinct signaling pathways. Either phosphatidylinositol (PI) 3-kinase or mitogen-activated protein kinase kinase (MEK) antagonized p53-induced apoptosis, and an additive preventive effect was observed when both kinases were activated. However, the combination of PI 3-kinase and MEK was not sufficient to completely prevent apoptosis induced by DNA damage. Mitogen activation further suppressed cisplatin-induced p53 expression, and the inhibition was mainly dependent on the Ca2+ pathway. Our results demonstrate that effective antagonism of p53-dependent apoptosis by mitogenic activation requires the presence of multiple signal pathways, including PI 3-kinase, MEK, and Ca2+.

Animals↗