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Biomedical subjects

W Sun

Publications and source records attributed to W Sun.

At least 109 records · Page 6Linked to original sources
PubMed2000

In vitro demonstration of IgE antibody to folate-albumin in anaphylaxis from folic acid.

BACKGROUND: Folic acid (the synthetic form of folate B vitamins in foods) is widely used in vitamin supplements. Anaphylaxis from ingestion or injection of folic acid suggests IgE antibody-mediated mechanisms, but this has not been demonstrated previously in vitro. OBJECTIVE: This study was conducted to better define the mechanism of folic acid hypersensitivity and cross-reactivity among folic acid congeners. METHODS: Skin testing was performed with folic acid congeners in a woman who developed anaphylaxis after ingestion of 2 different multivitamin preparations containing folic acid. In vitro immunologic serum studies were conducted using a folate-human serum albumin (HSA) conjugate prepared by a novel application of carbodiimide condensation. RESULTS: The patient had positive immediate-type skin test reactions to folic acid and several folate analogues including leucovorin (folinic acid). Urticaria developed during graded oral test dosing with leucovorin. Using a dot immunoblot assay or an ELISA for IgE antibody to folate-HSA, results of the patient's serum testing were positive, whereas results of sera from normal control subjects were negative, the first in vitro demonstration of IgE to a folic acid-protein conjugate. By ELISA, the positive result of the patient's serum was inhibited significantly by serum coincubation with folate-HSA, but not HSA or folic acid. CONCLUSIONS: Immediate hypersensitivity to folic acid and possibly other vitamins can be mediated by IgE antibody to conjugates formed between vitamins and self-proteins or polypeptides. Leucovorin can have clinically important immunologic cross-reactivity with folic acid. A diet rich in natural folates (pteroylpolyglutamates) appears useful as a management strategy for providing adequate nutrition to patients with folic acid hypersensitivity.

Adult↗
PubMed2000

A novel secretory protein produced by rat spongiotrophoblast.

The placenta secretes various factors in stage- and cell-specific manners. We have identified a cDNA encoding a novel protein with 124 amino acids, which was named spongiotrophoblast specific protein (SSP). SSP is highly homologous to mouse 4311, showing 81% and 59% similarity at the nucleotide and amino acid levels, respectively. Northern blot analysis showed that SSP mRNA was first detected on Day 14 of pregnancy, peaked on Day 16, and remained elevated until term. In situ hybridization analysis showed that SSP mRNA was specifically expressed in spongiotrophoblast cells of Day 20 placenta but not in Day 12 placenta. No expression was detected from the differentiated or undifferentiated rat choriocarcinoma Rcho-1 cell line. Native SSP was detected as a 19-kDa molecule by Western blotting in cell extracts prepared from the junctional zone. SSP was predicted to be a secretory protein, because 1) a hydropathy test revealed that SSP contained an N-terminal hydrophobic region and 2) native SSP was also detected in the cultured media of junctional zone explants. To further investigate a potential signal peptide of this protein, sets of recombinant SSP were generated using a COS7 transfection system. The N-terminal amino acid sequence of secreted recombinant SSP confirmed that the N-terminal 17 amino acids had been cleaved to produce a secretory protein. Thus, we have identified and cloned a novel secretory protein, SSP, which is specifically expressed by rat spongiotrophoblast cells during the latter half of pregnancy.

Amino Acid Sequence↗
PubMed2000

An uncommon phenotype of poor inducibility of CYP1A1 in human lung is not ascribable to polymorphisms in the AHR, ARNT, or CYP1A1 genes.

Cigarette smoking can induce CYP1A1 in the lung. Induction requires the aryl hydrocarbon receptor (AHR) and aryl hydrocarbon receptor nuclear translocator (ARNT) proteins. Lung samples from seven of 75 Finnish patients who smoked until the time of surgery exhibited absent or low levels of CYP1A1 protein, mRNA and enzymatic activity, suggesting that these individuals might be genetically non or poorly inducible for CYP1A1. All seven lung samples expressed normal levels of AHR mRNA and ARNT mRNA, indicating that they did not carry inactivating polymorphisms in the 5' upstream regulatory regions of these genes. Sequencing of cDNAs encompassing the complete coding regions of AHR and ARNT identified a previously known codon 554 polymorphism in AHR, which was present in the homozygous state in one individual. This polymorphism, which leads to an amino acid substitution, has previously been reported either to have no effect or to enhance CYP1A1 induction. Previously unreported silent single nucleotide polymorphisms were identified in codon 44 of AHR and codon 189 of ARNT. 1500 bp of genomic sequence from the 5' upstream regulatory sequence of the CYP1A1 gene was also sequenced in the non-inducible individuals. A nucleotide substitution polymorphism at position -459 was detected in the heterozygous state in two individuals. This polymorphic site does not reside in any known regulatory sequence. The complete CYP1A1 coding sequence and intron/exon boundaries were then sequenced. None of the non or poorly inducible individuals exhibited any polymorphisms, either homozygous or heterozygous compared to representative inducible individuals or the previously published CYP1A1 sequence. Thus, no polymorphisms in the AHR, ARNT or CYP1A1 genes were identified that could be responsible for the non/low inducibility phenotype observed.

Aryl Hydrocarbon Receptor Nuclear Translocator↗
PubMed2000

Endoscopic goniotomy with the free electron laser in congenital glaucoma rabbits.

PURPOSE: Goniotomy is a surgical treatment of choice to treat primary infantile glaucoma. Goniotomy has been studied in vitro in animal and human cadaver eyes with several lasers. The objective of this study was to investigate the functional and morphologic effectiveness of goniotomy with the free electron laser in comparison with conventional needle goniotomy in early congenital glaucoma rabbits. MATERIALS AND METHODS: Ten rabbits with early congenital glaucoma underwent goniotomy over 100 to 120 degrees with a needle or the free electron laser. The wavelength was 6.45 microm, and the energy level ranged from 2.2 to 3.5 mJ at 30 Hz. Because most corneas were edematous in these rabbits, an Olympus 0.8-mm diameter endoscope was coupled to the laser waveguide or the needle and inserted into the anterior chamber filled with a viscoelastic material to perform the goniotomy. Intraocular pressures were followed up to 3 weeks before an acute goniotomy was performed in the contralateral eye. All eye specimens were processed for light microscopic evaluation. RESULTS: Incision of the pectinate ligaments and underlying trabecular meshwork was visualized through the endoscope on a video monitor during the surgeries. The mean intraocular pressure decreased after free electron laser goniotomy and after needle goniotomy, and the edematous corneas became clear in some cases. Histologic study showed successful lysing of the pectinate ligaments by the free electron laser with no obvious collateral thermal damage. However, some areas of peripheral anterior synechiae occurred. Similar results were observed in needle goniotomy cases. CONCLUSIONS: The free electron laser is capable of performing goniotomy in rabbit eyes with lower intraocular pressures in treated eyes 3 weeks after surgery. The histologic results of free electron laser goniotomy are comparable to those of conventional goniotomy. The endoscope provides beneficial visualization to perform the goniotomy in eyes with edematous corneas. The rabbit with early congenital glaucoma is also a useful infantile glaucoma surgical model.

Animals↗
PubMed2000

P wave and far-field R wave detection in pacemaker patient atrial electrograms.

This study was undertaken to develop and test a morphology-based adaptive algorithm for real-time detection of P waves and far-field R waves (FFRWs) in pacemaker patient atrial electrograms. Cardiac event discrimination in right atrial electrograms has been a problem resulting in improper atrial sensing in implantable devices; potentially requiring clinical evaluation and device reprogramming. A morphology-based adaptive algorithm was first evaluated with electrograms recorded from 25 dual chamber pacemaker implant patients. A digital signal processing (DSP) system was designed to implement the algorithm and test real-time detection. In the second phase, the DSP implementation was evaluated in 13 patients. Atrial and ventricular electrograms were processed in real-time following algorithm training performed in the first few seconds for each patient. Electrograms were later manually annotated for comparative analysis. The sensitivity for FFRW detection in the atrial electrogram during off-line analysis was 92.5% (+/- 10.9) and the positive predictive value was 99.1% (+/- 1.8). Real-time P wave detection using a DSP system had a sensitivity of 98.9% (+/- 1.3) and a positive predictivity of 97.3% (+/- 3.5). FFRW detection had a sensitivity of 91.0% (+/- 12.4) and a positive predictivity of 97.1% (+/- 4.2) in atrial electrograms. DSP algorithm tested can accurately detect both P waves and FFRWs in right atrium real-time. Advanced signal processing techniques can be applied to arrhythmia detection and may eventually improve detection, reduce clinician interventions, and improve unipolar and bipolar lead sensing.

Adolescent↗
PubMed2000

VIP and PACAP induce shift to a Th2 response by upregulating B7.2 expression.

VIP and PACAP, two structurally related neuropeptides produced within the lymphoid microenvironment, modulate several immunological functions. Although primarily anti-inflammatory in nature, VIP and PACAP also affect resting macrophages. In this study, we report on the role of VIP and PACAP on macrophage B7 expression and costimulatory function for antigen-primed CD4+ T cells, and on the macrophage-induced regulation of Th1/Th2 differentiation in vitro and in vivo. VIP and PACAP upregulate B7.2, but not B7.1, MHC class II, or ICAM-1 expression, and activate macrophages to stimulate the proliferation of naïve T cells in response to soluble anti-CD3 or allogeneic stimulation. The stimulatory effect is mediated through the specific receptor VPAC1, and involves the cAMP/PKA pathway as second messengers. The enhancement in B7.2 expression occurs at both mRNA and protein levels, and correlates with the VIP/PACAP induced upregulation of the costimulatory activity of macrophages for antigen-primed CD4+ T cells. VIP/PACAP-treated macrophages gain the ability to induce Th2-type cytokines such as IL-4 and IL-5, and to reduce Th1-type cytokines such as IFN gamma and IL-2. In vivo administration of VIP or PACAP in antigen-immunized mice reduces the numbers of IFN gamma-secreting cells, enhances the numbers of IL-4-secreting cells, and affects the pattern of antigen-specific Ig isotypes. The preferential differentiation into Th2 effector cells induced by VIP/PACAP-treated macrophages is mediated through the upregulation of B7.2 expression. Since Th1-dominated responses are associated with some autoimmune diseases and inflammatory reactions typical of cell-mediated immunity, the VIP/PACAP inhibition of Th1 development may represent an additional mechanism for the general anti-inflammatory activity of the two neuropeptides.

Animals↗
PubMed2000

Identification of exon-deleted progesterone receptor mRNAs in human uterine endometrial cancers.

We demonstrated the expression of various exon-deleted progesterone receptor (PR) variant mRNAs in human uterine endometrial cancers using the reverse transcription-polymerase chain reaction-DNA sequencing analyses. In addition to PR wild-type mRNA, exon 4-deleted, exon 6-deleted, exon 3,4-deleted, exon 5,6-deleted, exon 4,5,6-deleted and exon 3,4,5,6-deleted PR variant mRNAs were identified. The exon 6-deleted and exon 5,6-deleted PR variant mRNAs lacked encoding for the steroid-binding domain. The exon 4-deleted, exon 3,4-deleted, exon 4,5,6-deleted and exon 3,4,5,6-deleted PR variant mRNAs lacked encoding for the DNA-binding domain in addition to encoding for the steroid-binding domain. While the exon 4-deleted, exon 6-deleted and exon 3,4-deleted PR variant mRNAs were observed in all samples analyzed, the exon 5,6-deleted, exon 4,5,6-deleted and/or exon 3,4,5,6-deleted PR variant mRNAs could not be detected in some cases, especially in poorly differentiated adenocarcinoma as compared with well-differentiated and moderately differentiated adenocarcinomas. The present study demonstrates the coexpression of PR exon-deleted variant mRNAs with the wild-type in uterine endometrial cancers. All translated variant proteins might possess functional diversity and might modify the progestational action of wild-type PR, and the expression of some PR variant mRNAs may be lost as endometrial cancer cells undergo dedifferentiation.

Endometrial Neoplasms↗
PubMed2000

Blood pressure, LDL cholesterol, and intima-media thickness: a test of the "response to injury" hypothesis of atherosclerosis.

The "response to injury" hypothesis is a plausible model of the development of atherosclerosis supported by observations from animal models. The present study uses epidemiological data to investigate the hypothesis that wall damage due to hypertension is a precursor of low density lipoprotein cholesterol (LDL-C)-mediated atherosclerosis. The Los Angeles Atherosclerosis Study is following a cohort of 576 participants who were aged 40 to 60 years and were free of symptomatic cardiovascular disease at recruitment. Common carotid artery intima-media thickness (IMT) was assessed by B-mode ultrasonography. After exclusion for nonfasting blood draw and other missing data, 511 subjects were available for analysis. IMT was regressed on LDL-C within tertiles of systolic blood pressure (SBP): low (93 to 122 mm Hg), middle (123 to 132 mm Hg), and high (133 to 175 mm Hg). Covariates were age, sex, body height, body mass index, ethnicity, smoking status, diabetes, and pharmacological treatment for hypertension or hypercholesterolemia. IMT was significantly related to LDL-C in the high SBP group (beta=0.025+/-0.008, where beta values are IMT [mm]/LDL-C [mmol/L]; P=0.002) but not in the middle (beta=-0.006+/-0.008, P=0.39) or low (beta=-0.004+/-0.009, P=0.64) SBP group. The slope in the high SBP group was significantly greater than in the middle (P=0.004) or low (P=0.014) SBP group. Results were similar for women and men, and after the exclusion of diabetics and persons using antihypertensive or lipid-lowering medications. Elevated LDL-C was associated with increased IMT in the upper tertile of SBP but not in the lower tertiles. These findings are consistent with the hypothesis that wall injury due to elevated SBP increases the susceptibility of the artery wall to LDL-C-mediated atherogenesis.

Adult↗
PubMed2000

The replication capacity of intact mammalian nuclei in Xenopus egg extracts declines with quiescence, but the residual DNA synthesis is independent of Xenopus MCM proteins.

In eukaryotes, the initiation of DNA synthesis requires the assembly of a pre-replicative complex (pre-RC) at origins of replication. This involves the sequential binding of ORC (origin-recognition-complex), Cdc6 and MCM proteins, a process referred to as licensing. After origin firing, the Cdc6 and MCM proteins dissociate from the chromatin, and do not rebind until after the completion of mitosis, thereby restricting replication to a single round in each cell cycle. Although nuclei normally become licensed for replication as they enter G(1), the extent to which the license is retained when cells enter the quiescent state (G(0)) is controversial. Here we show that the replication capacity of nuclei from Swiss 3T3 cells, in Xenopus egg extracts, is not lost abruptly with the onset of quiescence, but instead declines gradually. The decline in replication capacity, which affects both the number of nuclei induced to replicate and their subsequent rate of DNA synthesis, is accompanied by a fall in the level of chromatin-bound MCM2. When quiescent nuclei are incubated in egg extracts, they do not bind further MCMs unless the nuclei are first permeabilized. The residual replication capacity of intact nuclei must therefore be dependent on the remaining endogenous MCMs. Although high levels of Cdk activity are known to block MCM binding, we show that the failure of intact nuclei in egg extracts to increase their bound MCMs is not due to their uptake and accumulation of Cdk complexes. Instead, the failure of binding must be due to exclusion of some other binding factor from the nucleus, or to the presence within nuclei of an inhibitor of binding other than Cdk activity. In contrast to the situation in Xenopus egg extracts, following serum stimulation of intact quiescent cells, the level of bound MCMs does increase before the cells reach S phase, without any disruption of the nuclear envelope.

3T3 Cells↗
PubMed2000

Effect of electromagnetic field exposure on chemically induced differentiation of friend erythroleukemia cells.

Whether exposure of humans to extremely low frequency electromagnetic fields (ELF-EMF) can cause cancer is controversial and therefore needs further research. We used a Friend erythroleukemia cell line that can be chemically induced to differentiate to determine whether ELF-EMF could alter proliferation and differentiation in these cells in a manner similar to that of a chemical tumor promoter. Exposure of this cell line to 60 Hz ELF-EMF resulted in a dose dependent inhibition of differentiation, with maximal inhibition peaking at 40% and 40 mG (4 microT). ELF-EMF at 10 mG (1.0 microT) and 25 mG (2.5 microT) inhibited differentiation at 0 and 20%, respectively. ELF-EMF at 1.0 (100) and 10.0 G (1,000 microT) stimulated cell proliferation 50% above the sham-treated cells. The activity of telomerase, a marker of undifferentiated cells, decreased 100[times] when the cells were induced to differentiate under sham conditions, but when the cells were exposed to 0.5 G (50 microT) there was only a 10[times] decrease. In summary, ELF-EMF can partially block the differentiation of Friend erythroleukemia cells, and this results in a larger population of cells remaining in the undifferentiated, proliferative state, which is similar to the published results of Friend erythroleukemia cells treated with chemical-tumor promoters.

Cell Differentiation↗
PubMed2000

Gene therapy for murine liver cancer by adenovirus-mediated cytosine deaminase gene.

OBJECTIVE: To investigate anti-tumor effects of AdCD/5FC system on mice bearing MM45T.Li liver cancer. METHODS: IC(50), bystander effect and cell apoptosis were observed in vitro. After treatment of the tumor with AdCD in situ and injection of 5FC peritoneally into the mice, the anti-tumor effects were observed. RESULTS: When MOI=100, AdCD infected MM45T.Li was sensitive to 5FC, and the IC(50) was less than 50 micromol/L. When 10% MM45T.Li cells were infected with AdCD, 72% cells died after 5FC treatment, which showed significant bystander effect. Through TUNEL test and Hoechst 33258 staining, it was demonstrated that there was cell apoptosis after AdCD/5FC treatment of the MM45T.Li cell 21 day after treatment of the mice bearing tumor. The tumor volume was reduced significantly (F=20.33, P<0.05), and the median survival time was prolonged from 41-43 day to 49 day. CONCLUSION: AdCD/5FC system shows significant anti-tumor effects.

Adenoviridae↗
PubMed2000

Irinotecan and UFT/leucovorin in patients with advanced cancers.

The combination of irinotecan and fluorouracil (5-FU) is synergistic when applied to human colon cancer cell lines in vitro and appears to be schedule-dependent: maximal activity occurs when irinotecan is administered prior to 5-FU. In this phase I study, irinotecan is administered in combination with UFT and leucovorin in patients with advanced solid tumors. Irinotecan is given as a 90-minute intravenous infusion on day 1 followed by twice-daily UFT plus oral leucovorin on days 2 through 15. Cycles are repeated every 21 days. Five patients have been treated to date; four are evaluable for toxicity. Starting doses were irinotecan 200 mg/m2/day, UFT 200 mg/m2/day, and leucovorin 60 mg/day. Preliminary results indicate that irinotecan in combination with UFT plus leucovorin is well tolerated at the initial doses (described in this article).

Administration, Oral↗
PubMed2000

Effect of nifedipine on proliferation and DNA synthesis of human gingival fibroblasts.

OBJECTIVE: To investigate the effect of Nifedipine, a calcium channel blocker, on cellular proliferation in gingival fibroblasts in vitro. METHODS: Gingival fibroblasts were cultured and incubated with various concentrations of Nifedipine (23.5, 108, 360, and 1200 ng/mL) for up to 7 days. RESULTS: Cell numbers were significantly different among these groups on the sixth and seventh days, especially between the 1200 ng/mL or 360 ng/mL and the other concentrations. CONCLUSION: Nifedipine can influence proliferation of gingival fibroblasts in high concentrations.

Adolescent↗
PubMed2000

[Detection and significance of lymph node micrometastases in patients with histologically node-negative gastric carcinoma].

OBJECTIVE: To study micrometastasis in lymph nodes from patients with node-negative gastric carcinoma according to routine histologic examination and its relevance to prognosis. METHODS: A total of 1,245 perigastric lymph nodes histologically free of metastasis from 105 patients were immunohistochemically stained with monoclonal antibody AE1 against low molecular weight cytokeratin for micrometastases. RESULTS: Micrometastases were observed in 81 lymph nodes(6.5%) of 31 patients (29.5%). The incidence of lymph node micrometastases was significantly higher in the diffuse type(22 of 53 cases, 41.5%) than in the intestinal type of gastric carcinoma (9 of 51 cases, 17.6%, P < 0.01). The presence of micrometastases was closely correlated with the size and invasion depth of primary tumor, but was not correlated with age, sex and location of the primary tumor. The 5-year survival rate after surgery was 61.3% and 82.4%, respectively in patients with and without micrometastases (P = 0.0116). When the number of lymph node with micrometastases was > or = 3, the 5-year survival rate significantly decreased. CONCLUSION: The detection of lymph node micrometastases is necessary to more accurately determine the clinical staging and prognosis of patients with node-negative gastric carcinoma by routine histologic examination.

Adult↗
PubMed2000

[The effects of the enameloplasty on the penetration and adaptation of sealant].

OBJECTIVE: To study the mechanism of enameloplasty technique by observing penetration and adaptation of sealant. METHODS: 60 extracted molars were selected and divided into three groups: pits and fissures of the samples in group A were prepared with bur(EST); those in group B were cleaned with cup-shaped brush(CST); group C, as control. RESULTS: The penetration of EST was (83.75 +/- 13.11)%, CST was (55.30 +/- 11.98)%. The presence of defects between sealants and inclines of cusp of EST and CST were 7.32% and 19.05% respectively, and between sealants and lateral walls of fissures were 16.07% and 38.93%. CONCLUSION: The penetration and adaptation of EST was superior to CST.

Dental Cavity Preparation↗
PubMed2000

[Simultaneous intrusion and retraction of the anterior teeth using a three-piece base arch].

OBJECTIVE: To evaluate the effects of the three-piece base arch on overbite correction of Class II malocclusion. METHODS: 20 patients with high angle, flared incisors were treated using a three-piece base arch appliance. The intrusion force of four upper incisors was adjusted to approximately 50 g. The line of force action was 2 mm distally to the resistant center(RC) and the retraction force was 20 g, the right and left posterior segments were joined by a palatal bar. Cephalograms were taken before treatment (T1) and six months after treatment (T2). RESULTS: The upper molars moved mesially 0.60 +/- 0.35 mm and the distance of the vertical extrusion was 0.80 +/- 0.52 mm. The distances of the upper central incisor retraction and intrusion were -4.20 +/- 2.12 mm and 3.10 +/- 0.54 mm respectively. The RC of the central incisor retracted -4.12 +/- 1.96 mm and intruded 3.20 +/- 0.66 mm. The axial inclination of the upper incisor-palatal plane changed from 123.21 degrees +/- 4.26 degrees to 116.00 degrees +/- 3.96 degrees. CONCLUSION: The three-piece segmented approach can effectively intrude and retract the upper anterior teeth for flared incisors and deep overbite.

Adolescent↗
PubMed2000

[Screening and fermentation conditions of a bacterial strain over-producing xylanase].

A xylanase producer WXULI-11 was isolated and identified as Pseudomonas sp. By combination treatment of WXULI-11 with UV and NTG, a mutant WLUN024 was obtained and its enzyme activity reached 354 IU/mL in 36 h by shaking flask. The mechanism of its xylanase production was primarily studied. The results showed that this enzyme was induced by xylan, xylose and some other xylosic material, while xylose had "two-way effect" on xylanase synthesis. Effects of nitrogen and other factors on enzyme production were also investigated.

Culture Media↗