Search PubMed⌕ Search

Biomedical subjects

S P Chen

Publications and source records attributed to S P Chen.

At least 19 recordsLinked to original sources
PubMed2004

Group I metabotropic glutamate receptors in spiral ganglion neurons contribute to excitatory neurotransmissions in the cochlea.

Evidence has accumulated over the years supporting glutamate as the primary neurotransmitter used by hair cells in afferent cochlear neurotransmission. Besides acting on ionotropic glutamate receptors, glutamate also activates second messenger systems via G-protein-coupled metabotropic glutamate receptors (mGluRs) to modulate neuronal excitability. However, it is unclear whether mGluRs participate in cochlear neurotransmission. We present evidence directly supporting a functional role for group I metabotropic glutamate receptors (mGluRIs) in spiral ganglion (SG) neurons. The presence of mGluRI and downstream G-protein subunits was demonstrated by molecular biology and immunolabeling methods. Direct activation of mGluRIs in cultured SG neurons resulted in transient increases of intracellular Ca(++) concentration and transient inward currents that gave rise to firings of multiple action potentials. These responses showed mGluRI pharmacological specificity and quickly desensitized. We next examined changes in cochlear function after noise exposure as a result of pharmacologically manipulating cochlear glutamate neurotransmission. These in vivo tests showed that blocking non-N-methyl-D-aspartic acid glutamate receptors was sufficient to eliminate compound action potentials of the auditory nerve, and pharmacologically inhibiting mGluRIs in the cochlea did not significantly affect the hearing threshold. In contrast, blocking mGluRIs lowered the amplitude of compound action potentials at louder sound levels and reduced the noise-induced temporary threshold shift. Our results suggest that although mGluRIs did not initiate fast excitatory cochlear neurotransmission, their activation contributed to the growth of excitatory responses of the cochlea. As a result, the cochlea was more resistant to noise-induced temporary hearing losses without the activation of mGluRIs in SG neurons.

Action Potentials↗
PubMed2003

Childhood nephrotic syndrome in relapse is associated with down-regulation of monocyte CD14 expression and lipopolysaccharide-induced tumour necrosis factor-alpha production.

Interleukin-13 (IL-13) is a known modulator of monocyte function, down-regulating monocyte surface markers such as CD14 and proinflammatory cytokines. We have shown previously that lymphocyte IL-13 gene expression was up-regulated during relapses in children with steroid-responsive nephrotic syndrome (SRNS). In this study, we examined the monocyte mRNA expression and lipopolysaccharide (LPS)-stimulated intracellular production of tumour necrosis factor-alpha (TNF-alpha) and IL-8 in children with SRNS during relapse and remission. Additionally, we investigated CD14 mRNA levels, CD14 surface expression and its soluble component (sCD14) in serum. Our results showed that the percentages of TNF-alpha positive monocytes following LPS stimulation were significantly lower in nephrotic children in relapse (64.4 +/- 13.7%) compared to remission (81.6 +/- 9.0%, P < 0.005). This was associated with down-regulation of CD14 mRNA, as well as both membrane and sCD14 in patients with nephrotic relapse (82.9 +/- 10.1% and 1.23 +/- 0.30 micro g/ml, respectively) compared to remission (93.9 +/- 3.2% and 1.77 +/- 0.82 micro g/ml, respectively) (P < 0.003). Although we demonstrated a decrease in LPS-stimulated intracellular production of TNF-alpha in monocytes from patients with nephrotic relapse, we were unable to show a concomitant decrease in mRNA expression during relapses. This could be explained by down-regulation of gene expression at the translational rather than transcriptional level. In conclusion, it is conceivable that up-regulation of T-cell IL-13 production in children with active nephrotic relapse was associated with suppression of monocyte CD14 expression, down-regulating pro-inflammatory cytokine production, and could account for the increased susceptibility to bacterial sepsis seen in nephrotic children in active relapse.

Adolescent↗
PubMed2003

Validation of a multiplex RT-PCR assay for screening significant oncogene fusion transcripts in children with acute lymphoblastic leukaemia.

In childhood acute lymphoblastic leukaemia (ALL), cytogenetics play an important role in diagnosis, allocation of treatment and prognosis. Conventional cytogenetic analysis, involving mainly karyotyping in our experience, has not been successful in a large proportion of cases due to inadequate metaphase spreads and poor chromosome morphology. Our aim is to develop a highly sensitive and specific method to screen simultaneously for the four most frequent fusion transcripts resulting from specific chromosomal translocations, namely, both the CML- and ALLtype BCR-ABL transcripts of t(9;22), E2A-PBX1 transcript of t(1;19), the MLL-AF4 transcript of t(4;11) and TEL-AML1 (also termed ETV6-CBFA2) of the cryptic t(12;21). A multiplex reverse transcription polymerase chain reaction protocol (RT-PCR) was developed and tested out on archival bone marrow samples and leukaemia cell lines. In all samples with a known translocation detected by cytogenetic techniques, the same translocation was identified by the multiplex-PCR assay. Multiplex RT-PCR assay is an effective, sensitive, accurate and cost-effective diagnostic tool which can improve our ability to accurately and rapidly risk-stratify patients with childhood ALL.

Child↗
PubMed2002

Optimization of foot-and-mouth disease vaccination protocols by surveillance of neutralization antibodies.

An appropriate immunization program for pigs in a foot-and-mouth disease (FMD) endemic area was proposed based on data analysis obtained from serological surveillance in Taiwan, after an intensive vaccination program. To provide an adequate passive immunity for piglets, gilts that have completed two basic vaccinations must be boosted once before breeding. To achieve an efficient response to the FMD vaccine for piglets born to well vaccinated sows, vaccination need to be delayed until 10-12 weeks of ages for the first immunization, followed by a boost 4 weeks later.

Animals↗
PubMed2001

[Expression of bcl-2, c-myc genes and their relationship in patients with acute leukemia].

OBJECTIVE: This paper was to explore the expressions of bcl-2, c-myc genes and the relationship between them in bone marrow from patients with acute leukemia (AL). METHODS: In situ hybridization was used to detect bcl-2 and c-myc mRNA. Immune cytochemistry was used to detect bcl-2 and c-myc protein. RESULTS: The expressions of bcl-2, c-myc mRNA and proteins were significantly increased in AL; There were not significant differences in bcl-2 mRNA and protein, c-myc mRNA and protein between the patients with acute lymphocytic leukemia and acute nonlymphocytic leukemia; There were linear correlations between bcl-2 mRNA and bcl-2 protein, between c-myc mRNA and c-myc protein, between bcl-2 mRNA and c-myc mRNA, between bcl-2 protein and c-myc protein. CONCLUSION: bcl-2 and c-myc genes play an important role in pathogenesis and the development of AL.

Female↗
PubMed2001

Junceol A, a new sesquiterpenoid from the sea pen Virgularia juncea.

A new sesquiterpenoid, junceol A(1), as well as two known diterpenoids, sclerophytin A (2) and cladiellisin (3), have been isolated from the sea pen octocoral Virgularia juncea. The structure of metabolite 1 was determined by extensive spectral analysis. Compounds 1-3 have been shown to exhibit cytotoxicity toward P-388 cancer cells.

Animals↗
PubMed2001

Polymorphism of human HLA-DRB1 antigens generated by genetic exchange between DR2 (DRB1*15011) and DR6 (DRB1*1405) alleles: a novel DRB1 allele (DRB1*1437) identified in a Paiwan tribe member of Taiwan.

We report herein the identification of a new DRB1 allele using sequence-based typing (SBT). This novel allele, HLA-DRB1*1437, was found in an aboriginal individual from the Paiwan tribe in the southern part of Taiwan. This individual was typed by SBT method as having an HLA genotype of HLA-A*02011/0203, HLA-B*15011/3901, HLA-DRB1*11011/1437, HLA-DRB3*0202/0202, and HLA-DPB1*0501/1301. This new allele differs from DRB1*1309 in the 5'-end nucleotide sequence of polymorphic exon 2 at codon 16 (CAT-->CAA; H16Q), codon 37 (AAC-->TTC; R37F), codon 47 (TTC-->TAC; F47Y), and codon 58 (GCC-->GCT; both specify alanine). By sequence comparison, it was found that this new allele has a 5'-end sequence (from amino acid residues 7 to 66) identical to that found in the DRB1*1405 allele and a 3'-end sequence (from amino acid residues 58 to 94) identical to that found in the DRB1*15011 allele. Both DRB1*1405 and DRB1*15011 alleles have been identified among the Paiwan members (Note).

Alleles↗
PubMed2001

New DR5 sequences: a novel DRB1*11122 allele identified in Paiwan tribe members of Taiwan and a corrected sequence for the DRB1*1201 allele.

We report herein the identification of a new DRB1 allele using sequence-based typing (SBT). This novel allele, HLA-DRB1*11122, was found in an aboriginal individual (SWP71) from the Paiwan tribe in the southern part of Taiwan. This individual was typed by SBT method as having an HLA genotype of HLA-A*24021/24021, HLA-B*4001/4002, HLA-DRB1*11122/15011, HLA-DRB3*0202, and HLA-DRB5*01011. This new allele differs from DRB1*1112 in the polymorphic exon 2 only at codon 34 (CAA-->CAG; both specify glutamine) and from DRB1*1110 in the exon 2 sequence only at codon 32 (CAT-->TAT; H32T). The most likely candidate allele which is found in the aboriginal populations of Taiwan and which may mutate into this new allele is DRB1*11011. DRB1*11122 allele differs from DRB1*11011 allele in the polymorphic exon 2 at both codon 34 (CAA-->CAG) and codon 37 (TAC-->TTC; T37F). This novel HLA-DRB1*11122 allele was also found in another aboriginal individual (SWP90) from the same Paiwan tribe. This SWP90 individual was typed by SBT method as having an HLA genotype of HLA-A*24021/24021, HLA-B*4002/5502, HLA-DRB1*11122/1201, and HLA-DRB3*01011/0202. However, the original DRB1*1201 sequence from HERLUFF was found to be erroneously reported and the corrected sequence from SWP90 is now presented herein.

Alleles↗
PubMed2000

Intelligence and event-related potentials for young female human volunteer apolipoprotein E epsilon4 and non-epsilon4 carriers.

The apolipoprotein E (APOE) epsilon4 allele is associated with late-onset Alzheimer's disease and cognitive function in aging normal populations. To study the effect of the presence of the epsilon4 allele on cognitive function, we compared intelligence-test scores and component values for event-related potentials for epsilon4 and non-epsilon4 carriers in a group of 134 young females. The results demonstrate modest increases in performance intelligence quotient (IQ) and N100 amplitude for epsilon4 carriers (P=0.038 and 0.068, respectively). Our findings suggest that cognitive impairment, associated with the presence of the epsilon4 allele, is age-dependent and thus not probable for young women. The higher performance IQ scores demonstrated for epsilon4 carriers require further exploration.

Adult↗
PubMed1999

Competency in community-oriented health care. Instrument development.

To competently deal with changes in the health care system, health professionals for the future must have expanded abilities and new attitudes. Education of health professionals for community-oriented health care (COHC) is being promoted as one approach to achieve this focus. This article reports on the development and testing of the Community-Oriented Health Care Competency Scale, which measures knowledge, attitudes, and intention to practice COHC. Results of testing demonstrate adequate reliability for a new instrument: an alpha coefficient of .95 for the Knowledge subscale, .68 for the Attitude subscale, and .93 for the Intention to Practice subscale. Content Validity of the instrument is based on the literature review, focus group sessions, and expert opinion. The instrument may be used to assess competency of health professions students in COHC, but continued testing is needed.

Community Health Services↗
PubMed1998

Experiences of African American adolescent fathers.

Social and cultural factors influence the experience of fatherhood. This descriptive focus-group study describes the lived experience of fatherhood from the perspectives of 5 unmarried, low-income, African American adolescent fathers in a Midwestern urban area. Naturalistic inquiry approach guided the study. Seven themes of fatherhood emerged: barriers to fatherhood, value of fatherhood, introduction to fatherhood, competencies of fatherhood, role-set relationships, social norms of fatherhood, and father-child contact. This study suggests that nurses should support the involvement of adolescent fathers with their children. Future study may determine the influence of adult female family members on the decisions of adolescent fathers to remain involved with their children.

Adolescent↗
PubMed1998

Noise induced hearing loss among male airport workers in Korea.

The purposes of this study of airport workers were to a) determine the prevalence and symptoms of hearing loss, and b) identify compliance in using hearing protective devices (HPDs) and its relationship with hearing loss. This cross sectional epidemiological study was conducted with 255 noise exposed and 195 non-noise exposed, full time, male workers at a large metropolitan airport in Seoul, Korea. The three measures used were the self administered Occupational Hearing Questionnaire (OHQ), an audiological assessment, and a record review of baseline hearing and noise levels of locations in which the employee worked. The results showed a significant difference in prevalence of hearing loss (more than 25dB) between the noise and the non-noise exposed groups (p < .05). About 60.8% of noise exposed workers reported continuous use of the HPDs. The continuous HPD users had significantly lower rates of hearing loss than the occasional users or non-users. The major symptom for workers with low frequency hearing loss was trouble in communication, whereas tinnitus and fullness in the ear were the most common symptoms for the workers with high frequency hearing loss. The airport workers exposed to excessive noise had a great deal of high frequency hearing loss. The degree of hearing loss present reinforces the need for aggressive hearing conservation programs among airport workers exposed to noise.

Adult↗
PubMed1997

XTT-colorimetric assay as a marker of viability in cryoprocessed cardiac valve.

This study sought to evaluate the use of tetrazolium salt XTT reduction as an indicator of valvular viability in a cryoprocessed porcine cardiac homograft model. The XTT tetrazolium assays was based on the metabolic reduction of Sodium 3'-[1-(phenylamino-carbonyl)-3,4-Tetrazolium]-bis(4-methoxy-6-nitro) benzene sulfonic acid hydrate. The relationship between XTT reduction and: (1) leaflet tissue with various weight (n = 24); (2) morphometric evaluation (n = 30); (3) cadaveric ischemic intervals (n = 30); (4) freeze-thawing (n = 30) has been studied. The measurement of XTT reduction were significantly correlated with the weight of cardiac leaflets, in the range of 30 to 180mg (y=0.015x-0.063; r=0.99). Compared to morphometry of valvular damage, the reduction of mitochondrial enzymatic activity in cardiac leaflets was correlated with matrix cells without irreversible damage (r=0.89, P<0.005). The depletion of XTT reduction occurred dependent of ischemic time intervals. In general, freeze-thawing reduced more than 20% activity of mitochondrial dehydrogenase. We concluded that XTT tetrazolium assay is highly sensitive to determine valvular injury. The study demonstrated its potential for testing of cryopreserved cardiac valve.

Animals↗
PubMed1997

Validity of three lumbar sagittal motion measurement methods: surface inclinometers compared with radiographs.

Three surface methods for measuring lumbar sagittal motion (LSM) were tested for validity using radiographs as the "gold standard" reference. The three methods used were the Pleurimeter V double inclinometer, the carpenter double inclinometer, and the computerized sensor single inclinometer. In this study, 30 volunteers were examined independently by three occupational health professionals. Each volunteer rotated twice through three stations at which LSM was measured by each of the three methods. Radiographs were made during the first rotation. Predictability of the skin marks of T12 and S1 for the corresponding bone measures was acceptable for one examiner, mixed for another, and unacceptable for a third. The intraclass correlation coefficients (ICCs) ranged from 0.81 to 0.99, with half above the acceptable level of 0.90. However, the skin marks and the bone measures showed a linear relationship for all examiners (r > or = 0.89). For flexion and extension, all ICCs between the radiograph and each surface method were far below 0.90, indicating poor validity for each surface method. We concluded that skin placement of T12 and S1 has a linear relationship to bony landmarks, and that each of the tested surface methods does not validly measure LSM.

Adult↗
PubMed1997

Reliability of three lumbar sagittal motion measurement methods: surface inclinometers.

Three surface methods for measuring lumbar sagittal motion (LSM) were tested for reliability. The three methods used were the Pleurimeter V double inclinometer, the carpenter double inclinometer, and the computerized single sensor inclinometer. In this study, 30 volunteers were examined independently by three occupational health professionals. Each volunteer rotated twice through three stations at which LSM was measured by each of the three methods. The intra- and interexaminer reliabilities in identifying the skin levels of T12 and S1 were acceptable, having intraclass correlation coefficients (ICC) greater than or equal to 0.75. With a single exception, all ICC values for the intraexaminer reliability of LSM measurements fell below 0.90 (a clinically desirable level). The interexaminer reliability was poor, with all ICC values below 0.75. The largest source of measurement error was attributable to the examiner and its associated factors. We concluded that the intra- and interexaminer reliabilities varied greatly, limiting the clinical usefulness of the three surface methods.

Adult↗
PubMed1997

[Structure determination of three saponins from the stem bark of Albizzia julibrissin Durazz].

Three new saponins named Julibroside J1, J2 and J3 were isolated from the stem bark of Albizzia julibrissin Durazz (Albizziae Cortex). Based on chemical and spectral methods, e.g. 1H- and 13C-NMR, DEPT, COSY CH-COSY, TOCSY, HMQC-COSY, HMQC-TOCSY, NOESY, HMBC, their structures have been identified as; Julibroside J1 (one triterpene, nine sugars, two monoterpenes I); Julibroside J2(one triterpene, eight sugars two monoterpenes II); Julibroside J3(one triterpene, nine sugars two monoterpenes III).

Antineoplastic Agents↗