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Biomedical subjects

M Yen

Publications and source records attributed to M Yen.

18 recordsLinked to original sources
PubMed2001

MR staging of clinical stage I and IIa cervical carcinoma: a reappraisal of efficacy and pitfalls.

The purpose of this study was to evaluate the diagnostic efficacy and pitfalls of magnetic resonance (MR) imaging in preoperative staging of cervical cancer. MR imaging was performed to determine the tumor staging for 31 patients with cervical carcinoma emphasizing tumor size, parametrial invasion, vaginal invasion and lymph node metastases. Tumor size was 3.23+/-1.75 cm (mean+/-standard deviation) at MR imaging compared with 2.79+/-1.76 cm at surgical-pathologic evaluation. The discrepancy between the tumor size determined by MR imaging and the measured surgical specimens was consistent in tumors larger than 1 cm. In assessing parametrial invasion, vaginal invasion and lymph node metastases, MR imaging had an accuracy of 96.7 and 87%. In determining stage of disease and differentiating operable (< or =stage IIA) from advanced disease (> or =stage IIB), MR imaging had an accuracy of 83.8 and 96.7%. Pitfalls leading to staging errors included difficulties in differentiating cancer foci from surrounding tissue edema and excluding vaginal invasion in the presence of large cervical cancer. In conclusion, MR imaging is accurate in the evaluation of parametrial invasion and useful in the differentiation of operable from advanced disease. The ability of MR imaging to exclude vaginal invasion in the presence of large cervical cancer and differentiate cancer foci from surrounding tissue edema is not as reliable.

Adenocarcinoma↗
PubMed2000

Superantigen-induced CD4 T cell tolerance mediated by myeloid cells and IFN-gamma.

We have previously shown that systemic staphylococcal enterotoxin A (SEA) injections cause CD4 T cells in TCR-transgenic mice to become tolerant to subsequent ex vivo restimulation. An active IFN-gamma-dependent mechanism of suppression was responsible for the apparent unresponsiveness of the CD4 T cells. In this study, we analyze the response of CD4 T cells isolated throughout the first 10 days of the in vivo response to injected SEA. We show that CD4 T cells isolated at the peak of the in vivo response undergo very little activation-induced cell death after sterile FACS sorting or restimulation in the presence of neutralizing Abs to IFN-gamma. We also show that the IFN-gamma-dependent tolerance develops soon after SEA injection in the spleens of both normal and TCR-transgenic mice. This suppression is dependent upon myeloid cells from the SEA-treated mice and is optimal when inducible NO synthase activity and reactive oxygen intermediates are both present. The data indicate that IFN-gamma, myeloid cells, and a combination of NO and reactive oxygen intermediates all contribute to a common pathway of T cell death that targets activated or responding CD4 T cells. Sorted Gr-1(+) cells from SEA-treated mice also directly suppress the response of naive CD4 T cells in mixed cultures, indicating that this tolerance mechanism may play a role in down-regulating other vigorous immune responses.

Animals↗
PubMed2000

Two distinct stages in the transition from naive CD4 T cells to effectors, early antigen-dependent and late cytokine-driven expansion and differentiation.

Efficient peptide presentation by professional APC to naive and effector CD4 T cells in vitro is limited to the first 1-2 days of culture, but is nonetheless optimum for effector expansion and cytokine production. In fact, prolonging Ag presentation leads to high levels of T cell death, decreased effector expansion, and decreased cytokine production by recovered effectors. Despite the absence of Ag presentation beyond day 2, T cell division continues at a constant rate throughout the 4-day culture. The Ag-independent later stage depends on the presence of IL-2, and we conclude optimum effector generation depends on an initial 2 days of TCR stimulation followed by an additional 2 days of Ag-independent, cytokine driven T cell expansion and differentiation.

Amino Acid Sequence↗
PubMed1999

Recurrence and survival analyses of 1,115 cervical cancer patients treated with radical hysterectomy.

Many clinicopathological factors of cervical cancer are still controversial in their prognostic significance. The case records of 1,115 patients who received radical hysterectomy at the Veterans General Hospital, Taipei, from 1980 to 1989 were collected to evaluate prognosis-related factors by univariate and multivariate analyses. The pathology was reviewed retrospectively by one pathologist. Ten parameters known to be prognostic in the literature were included for analysis. Univariate analysis showed that patients with all these factors had higher recurrence rates. However, when the effects of parametrial invasion, progressive stage and stromal invasion were weighed against the presence of lymph node metastasis, their influence on recurrence became unimportant. Nevertheless, these factors still influenced prognosis when there was no lymph node metastasis. Multivariate analysis of both recurrence and survival time in the patients with squamous cell carcinoma shared a consensus that pelvic lymph node metastasis and deep stromal invasion were significant risk factors. We conclude that these simplified and consistent results obtained by multivariate analysis provide a basis for subclassification of patients to predict prognosis and change therapy.

Adenocarcinoma↗
PubMed1999

Granulocyte colony-stimulating factor on the growth of human ovarian carcinoma cells in vitro.

Granulocyte colony-stimulating factor (GCSF) is a member of a family of glycoprotein hormones that stimulates the proliferation and differentiation of hematopoietic cells in vivo and in vitro. In ovarian cancer chemotherapy, GCSF is used clinically to build up bone marrow function after severe cytotoxicity to granulocytes by chemotherapy. Little is known about the effects of these cytokines on the growth of cancer cells. To study the influence of GCSF on the proliferation of ovarian cancer cells in vitro, five established ovarian cancer cell lines (OC-89-VGH, OC-117-VGH, OCPC-2-VGH, NIH-OVCAR-3, and NIH-SK-OV-3) were treated with the concentration ranging from 0.1 pg to 10 ng GCSF for 5 days and compared with vehicle control. In addition, we also examined the effect of GCSF (0. 01-1.0 ng) on eight primary cultures of fresh ovarian cancer tissues. Cell viability after treatment was measured by Cell Titer AQueous assay and expressed as a percentage of untreated control cultures. A decrease in cell growth (75-85%) was observed in OC-89-VGH, OC-117-VGH and OCPC-2-VGH cell lines while NIH-OVCAR-3 and NIH-SK-OV-3 cells showed minimal growth stimulation. However, all dose-response curves were nonsignificant, suggesting indirect effects. In the eight fresh tumor primary cultures treated with GCSF, no statistical significant difference in growth was observed. In conclusion, our data suggest that GCSF has little or no growth-modulatory effect on human ovarian carcinoma in vitro. Therefore, the clinical use of GCSF is unlikely to have a direct effect on tumor growth.

Cell Division↗
PubMed1998

Functional differences between keratins of stratified and simple epithelia.

Dividing populations of stratified and simple epithelial tissues express keratins 5 and 14, and keratins 8 and 18, respectively. It has been suggested that these keratins form a mechanical framework important to cellular integrity, since their absence gives rise to a blistering skin disorder in neonatal epidermis, and hemorrhaging within the embryonic liver. An unresolved fundamental issue is whether different keratins perform unique functions in epithelia. We now address this question using transgenic technology to express a K16-14 hybrid epidermal keratin transgene and a K18 simple epithelial keratin transgene in the epidermis of mice null for K14. Under conditions where the hybrid epidermal keratin restored a wild-type phenotype to newborn epidermis, K18 partially but not fully rescued. The explanation does not appear to reside in an inability of K18 to form 10-nm filaments with K5, which it does in vitro and in vivo. Rather, it appears that the keratin network formed between K5 and K18 is deficient in withstanding mechanical stress, leading to perturbations in the keratin network in regions of the skin that are subjected either to natural or to mechanically induced trauma. Taken together, these findings suggest that the loss of a type I epidermal keratin cannot be fully compensated by its counterpart of simple epithelial cells, and that in vivo, all keratins are not equivalent.

Animals↗
PubMed1998

Pharmacological characteristics of MJ-451, a new benzopyran- derived ATP-sensitive potassium channel opener, in guinea pig isolated trachea.

In this study, we determined the pharmacological activities of MJ-451 (6-cyano-3S,4R-dihydro-2, 2-dimethyl-2H-3-hydroxy-4-[2-oxo-5S-1-hydroxmethyl)-1-pyrrolidinyl ]-1 -benzopyran) in guinea pig isolated trachea and compared its effects with those of cromakalim. MJ-451 (0.1-10 micromol/l) and cromakalim (0.01-1 micromol/l) produced concentration-dependent relaxation of guinea pig isolated trachea precontracted with carbachol (0.5 micromol/l) or histamine (1 micromol/l). MJ-451 (0.03-30 micromol/l), as well as cromakalim (0.03-30 micromol/l), caused a complete and concentration-dependent relaxation of guinea pig isolated trachea precontracted with 20 mmol/l KCl, but did not inhibit the spasmogenic effect of 80 mmol/l KCl. However, theophylline (30-3,000 micromol/l) caused a complete and concentration-dependent relaxation of guinea pig isolated trachea precontracted with either 20 or 80 mmol/l KCl. Propranolol (0.1 micromol/l) markedly antagonized the relaxant action of isoprenaline, but not that of MJ-451 in carbachol-contracted isolated trachea. 8-(p)-sulfophenyltheophylline (150 micromol/l), a selective P1 purinoceptor antagonist, had no effect against the tracheal relaxation induced by MJ-451, but markedly depressed the concentration-response curve of 5'-N-ethylcarboxamidoadenosine. Charybdotoxin (10 micromol/l), a large-conductance Ca2+-activated K+ channel blocker, failed to modify the relaxant activity of MJ-451 in carbachol-contracted isolated trachea. The ATP-sensitive K+ channel blocker, glibenclamide (0.1, 1 and 10 micromol/l) concentration-dependently antagonized the relaxant activity of MJ-451 in carbachol-contracted isolated trachea. It is concluded that MJ-451 is a selective ATP-sensitive K+ channel opener in the tracheal smooth muscle of the guinea pig.

Animals↗
PubMed1997

A generic method for the production of cell lines expressing high levels of 7-transmembrane receptors.

G-protein-coupled or 7-transmembrane receptors (7TMRs) are often studied after heterologous expression in mammalian cells such as COS-7, CHO-K1, or HEK-293s. In this paper, we describe the development of a rapid and generic method for producing stable Chinese hamster ovary cell lines expressing high levels of recombinant 7TMRs by N-terminal tagging these proteins with the hemagglutinin (HA) sequence. To illustrate the broad applicability of this technique, we have presented data from cell lines expressing a glycoprotein hormone receptor for follicle-stimulating hormone (FSHR), CXC- (CXCR-2), and CC-chemokine (CCR-1) receptors and peptide receptors from the somatostatin (SSTR1, 2, 5) and neuropeptide Y (NPY-Y2, -Y4 Rs) families. Typically, cell lines with a receptor density of 1 to 15 pmol/mg protein are produced with this method. The presence of the HA tag does not adversely affect the binding or functional activity of the receptors.

Amino Acid Sequence↗
PubMed1995

Constraints and perspectives of advanced practice nursing in Taiwan, Republic of China.

Although master's-prepared advanced practice nurses (APNs) are used intensively in the United States, they are uncommon in most other countries. Statistics about APNs across the world are difficult to interpret because the term "specialist" does not necessarily equate with graduate preparation. This article focuses on the difficulties of implementing advanced practice nursing in Taiwan. Suggestions for future actions that may decrease these problems are presented. Based on discussions with nurses from other Asian countries, these suggestions may apply to increasing the use of APNs in these countries as well as in Taiwan.

Education, Nursing, Graduate↗
PubMed1995

Integrity of the first metatarsophalangeal joint: a biomechanical analysis.

Five fresh-frozen cadaver feet obtained from traumatic amputations were tested during hyperdorsiflexion stress of the first metatarsophalangeal joint. Three different types of injury were observed: (1) rupture of the capsule proximal to the sesamoids, (2) rupture of the plantar plate distal to the sesamoids, and (3) rupture of the capsular structures medially, allowing a lateral swing of the sesamoids around the metatarsal head. Incomplete dislocation can be associated with significant damage to the plantar plate and other soft tissues of the foot.

Adult↗
PubMed1994

On measuring the third dimension of cultured endothelial cells in shear flow.

The stress in the endothelial cells induced by blood flow depends on the waviness of the blood-endothelium interface and the slopes at the junctions of neighboring cells in the direction of flow. The height and slope in the third dimension of the living endothelial cells cannot be measured by ordinary optical and electron microscopy. Here we show that interference microscopy meets the challenge. We measured the geometry of cultured confluent human vascular endothelial cells in a flow, and we found that in a normal section parallel to the flow, the absolute values of the surface slopes at the cell junctions were 0.70 +/- 0.02 (SE) and 0.80 +/- 0.02 (SE) at the leading and trailing edges of the cells, respectively, in a culture medium of osmolarity 310 mosM with a shear stress of approximately 1 N/m2. A reversal of the flow direction led to a reversal of the slope pattern. An increase in medium osmolarity above 310 mosM induced an initial decrease in the slopes followed by a return to normal, whereas a decrease in the osmolarity had a reversed effect. These results, in light of our previous theoretical analyses, show that tensile stress exists in the endothelial cell membrane, and that the mechanism of tension accumulation is a reality. The accumulation is not 100% because the membranes are not smooth at the cell junctions.

Blood Viscosity↗
PubMed1993

The A-1 antigen: a novel marker in experimental peripheral nerve injury.

Expression of the Schwann cell phenotype is regulated by signals from the adjoining axon. After axotomy, the Schwann cell ceases the production and maintenance of the myelin sheath and assumes phagocytic properties necessary to digest its own myelin. The molecular mechanisms responsible for this behavior remain unclear. A monoclonal antibody termed BIKS was produced after the immunization of mice with guinea pig lymphoid tissue. This antibody recognizes a cytoplasmic vesicle-associated molecule (A-1 antigen) which is abundant in all tissue macrophages but is also expressed in small amounts in normal Schwann cells. Following axotomy, the A-1 antigen appears to be translocated from a perinuclear site to accumulate in large quantities around myelin ovoids in Schwann cells, as well at the nodes of Ranvier-sites where Wallerian degeneration is known to commence. The level of the antigen remains high when axons are prevented from regeneration. During repair of crush injury, however, the level of antigen drops concomitant with the ingrowth of regenerating axons, suggesting axonal control of A-1 antigen expression.

Animals↗
PubMed1993

Epstein-Barr virus and the lacrimal gland pathology of Sjögren's syndrome.

The lacrimal gland (LG) immunopathology of Sjögren's syndrome (SS) consists of a proliferation of B and CD4 lymphocytes surrounding epithelial structures (Pepose JS, et al: Ophthalmology 1990, 97:1599-1605). Based on the detection of EBV genomes in a greater percentage of SS than normal LG biopsies, we previously postulated that Epstein-Barr virus (EBV) is a risk factor for LG lymphoproliferation in SS (Pflugfelder SC, et al: Ophthalmology 1990, 97:976-984). The purpose of this study was to determine the cellular site(s) of infection, virus type, and antigen expression of EBV infecting normal and SS LGs. EBV DNA was detected by in situ hybridization in intraductal epithelia in 13-33% of lobules in 21% of normal LGs and in cells in areas of B lymphoproliferation as well as the majority of epithelia in 86% of SS LGs. EBV genomic sequences were amplified from 36% of normal and 88% of SS LG biopsies by polymerase chain reaction. Only type 1 EBV sequences were amplified in SS LGs; in contrast EBV nuclear antigen 2-deleted but not type 1 sequences were amplified in normal LGs. Immunohistochemistry with EBV-specific monoclonal antibodies was performed on normal and SS LGs. No EBV antigens were detected in normal LGs. In contrast, latent antigens (latent membrane protein, EBV nuclear antigen 2) were detected in lymphocytes in areas of B lymphoproliferation, and early and late lytic cycle antigens were observed in epithelia in SS LGs. These studies suggest that EBV may play a role in the LG B lymphoproliferation and epithelial pathologic changes observed in SS.

Adult↗
PubMed1991

Methotrimeprazine versus meperidine and dimenhydrinate in the treatment of severe migraine: a randomized, controlled trial.

STUDY OBJECTIVE: To compare the effectiveness of IM administration of methotrimeprazine, a non-narcotic, nonaddicting phenothiazine derivative, with that of a combination of meperidine and dimenhydrinate in the treatment of severe migraine. DESIGN: Double-blind, randomized, controlled trial. SETTING: University hospital emergency department. PARTICIPANTS: Consecutive adult patients with migraine who met eligibility criteria. INTERVENTIONS: Random allocation to receive IM injections of either 37.5 mg methotrimeprazine (Levoprome, Nozinan) or 75 mg meperidine (Demerol) combined with 50 mg dimenhydrinate (Dramamine, Gravol). MEASUREMENTS AND MAIN RESULTS: The 37 patients in each group who completed the study were similar in all demographic and clinical characteristics. There were no statistical differences in pain intensity one hour after treatment, change in pain intensity, or pain relief as measured on a visual-analog scale; need for additional analgesia; persistence of nausea or vomiting; adverse effects; or follow-up status, except for prolonged drowsiness, in the group receiving methotrimeprazine. CONCLUSION: Methotrimeprazine is comparable to meperidine with dimenhydrinate for treating severe migraine and may be considered an effective, nonaddicting, IM alternative to narcotics for the management of this problem.

Adolescent↗
PubMed1986

Domperidone, a new dopamine antagonist.

Domperidone is a dopamine antagonist that has recently been released in Canada. Unlike metoclopramide hydrochloride, the other available dopamine antagonist, it does not readily enter the central nervous system. Domperidone acts as both an antiemetic and an upper gastrointestinal tract prokinetic agent. It is rapidly absorbed after oral administration, and few side effects have been reported. Domperidone has been approved for use in Canada for the symptomatic management of upper gastrointestinal tract motility disorders and to prevent gastrointestinal symptoms associated with the use of dopamine agonist agents in Parkinson's disease. The pharmacologic features, indications and side effects of domperidone are reviewed.

Administration, Oral↗
PubMedDate not supplied

Detection of the complement (CD21)/Epstein-Barr virus receptor in human lacrimal gland and ocular surface epithelia.

CD21, the receptor for the C3d complement fragment, has been reported to be the Epstein-Barr virus (EBV) receptor in B lymphocytes and cultured squamous epithelial cells. This receptor has previously been found to be expressed in the epithelia of nonocular mucosal-associated lymphoid tissues (MALT) which are also sites of persistent EBV infection. We recently found evidence of persistent EBV infection in human ocular MALT and hypothesized that the epithelia in these tissues may also express the complement (C3d)/EBV receptor. To test this hypothesis, histologic sections of human lacrimal gland, ocular surface tissue (conjunctiva, limbus, and cornea), and conjunctival impression cytology specimens were stained by immunohistochemical techniques using three different anti-CD21 monoclonal antibodies (HB-5, B2, OKB7). HB-5 stained lacrimal gland ductal and all ocular surface epithelia, except limbus. B2 stained lacrimal gland ductal and limbal epithelia, and OKB7 stained only the limbal and corneal epithelia. The intensity of limbal and corneal epithelial staining with all anti-CD21 antibodies correlated with the level of epithelial differentiation, with the weakest staining noted in the cells which are thought to be the stem and transient amplifying cells of the cornea. These results suggest that external ocular tissues, similar to other MALT, have CD21-positive epithelia which may be potential targets for EBV infection.

Antibodies, Monoclonal↗