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Biomedical subjects

W F Chen

Publications and source records attributed to W F Chen.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Multiple types of cytokines secreted by a mouse fetal liver stromal cell line].

A murine fetal liver stromal cell line, called MFLC, has been established and maintained in DME supplemented with 10%NCS for 2 years. Without exogenous stimulation, the MFLC cells spontaneously secreted several types of cytokines, including IL-6, GM-CSF and chemotactic factor. Of which, IL-6 and chemotactic factor were abundant, GM-CSF at low level. Biological activities of IL-7 and IL-3 were not detected in the MFLC cell's supernatants. MFLC-SN induced colony formation of murine bone marrow cells in a dose dependent fashion in which mixed granulocyte/macrophage/megakaryocyte colonies(CFU-GMM) and granulocyte/macrophage colonies(CFU-GM) were dominant. MFLC-SN also sustained colony formation of bone marrow cells taken from 5-Fu injected mice, suggesting that there was a biological activity similar to SCF in MFLC-SN. The cytokines secreted by MFLC might play an important role in T cell early development in fetal liver. These results will be useful for us to analyse the mechanism of T cell development in fetal liver and to study the cytokine network regulation.

Animals↗
PubMed1997

Surgical management of grades III and IV primary vesicoureteral reflux in children with and without acute pyelonephritis as breakthrough infections: a comparative analysis.

PURPOSE: Although high grade vesicoureteral reflux associated with breakthrough infection may be an indication for surgical intervention, it remains uncertain whether acute pyelonephritis as breakthrough infection is a risk for renal scar formation and whether surgery performed without it has any advantage. We assessed the results of antireflux surgery for high grade vesicoureteral reflux in children with and without acute pyelonephritis as breakthrough infections. MATERIALS AND METHODS: A total of 33 boys and 27 girls (102 refluxing units) less than 3 years old with grades III and IV vesicoureteral reflux who underwent surgical management because of breakthrough infections were retrospectively studied in a 3-year period. Of the 60 patients 30 (group 1) presented with breakthrough infections of acute pyelonephritis, although they were maintained on prophylactic antibacterials. The remaining 30 patients (group 2) underwent surgery without acute pyelonephritis as the breakthrough infections. There was no renal scar formation at the diagnosis of vesicoureteral reflux in either group. Patients with renal scars were excluded from study. There was no significant difference in patient gender (p = 0.795) or distribution of bilateral vesicoureteral reflux (p = 0.781) in the groups. Group 1 patients were significantly younger at the diagnosis of vesicoureteral reflux (p = 0.006). RESULTS: Although 55 patients presented with a febrile urinary tract infection at the diagnosis of vesicoureteral reflux, the infection was not significantly related to the development of renal scars (p = 0.066). Of the 55 patients 12 presented with acute pyelonephritis as the initial episode of urinary tract infection. The presence of acute pyelonephritis at the diagnosis of vesicoureteral reflux was also not significantly related to renal scar formation (p = 0.207). Postoperative urinary tract infections developed in 34 patients but there was no significant correlation between postoperative urinary tract infections and renal scar formation (p = 0.235). At followup 17 group 1 and 7 group 2 patients (29 renal units) were found to have renal scars. CONCLUSIONS: Renal scars were significantly more common in younger children with than without acute pyelonephritis as breakthrough infections (p = 0.010). Although breakthrough infections in high grade reflux may be an indication for antireflux surgery, the most appropriate results were achieved when acute pyelonephritis was not a breakthrough infection.

Acute Disease↗
PubMed1996

Alteration of cerebral microcirculation by hemodilution with hemosome in awake rats.

Our study showed that hemodilution with modified fluid gelatin resulted in an increase in local cerebral blood flow (LCBF), but no change at all in local cerebral oxygen delivery (LCOD) in rats. Hemosome, a lecithin encapsulated hemoglobin having the oxygen-carrying capacity, was developed to improve LCOD by hemodilution. Therefore, we have hypothesized that LCBF & LCOD would be increased by hemodilution with hemosome. To test this hypothesis, adult male Sprague-Dawley rats weighing approximately 350g were used and divided into the hemodilution and the control groups. Hemosome was made from pig red blood cells and lecithin. It's mean diameter was approximately 0.3 um and hemoglobin concentration was approximately 4g/dl. Isovolemic hemodilution, which lowered the systemic hematocrit from approximately 50% to approximately 30%, was achieved by rapidly replacing blood with the same volume of hemosome. Ten min later, LCBF in 14 brain structures were measured using the 14C-iodoantipyrine technique. Our results showed that LCBF of the control group ranged from 115 +/- 11 ml/100g/min in the medulla to 260 +/- 31 ml/100g/min in the occipital cortex. LCBFs were generally higher (p < 0.05, MANOVA) by 16% in the hemodilution group than in the control group. However LCODs were generally decreased (p < 0.05, MANOVA) by 18% in the hemodilution group than in the control. In conclusion, hemodilution with hemosome indeed improves LCBF but lowers LCOD in awake rats.

Analysis of Variance↗
PubMed1996

Isolation of a lymphocyte chemotactic factor produced by the murine thymic epithelial cell line MTEC1: identification as a 30 kDa glycosylated form of MCP-1.

A medullary-type murine thymic epithelial cell line (MTEC1) established in our laboratory constitutively produces multiple species of chemotactic factors, which attract lymphocytes, neutrophils, and monocytes. Chemotactic proteins were isolated from MTEC1 supernatant and purified to homogeneity by adsorption to controlled pore glass, heparin-Sepharose chromatography, cation-exchange FPLC and RP-HPLC. A chemotactic factor for both lymphocytes and monocytes was identified as a 30 kDa protein by SDS-PAGE analysis under reducing conditions. After cleavage of the NH2-terminally blocked protein with formic acid, the amino acid sequence of the internal fragment was analysed and found to be identical to the amino acid sequence of mouse MCP-1/JE. The protein is hence identified as a glycosylated natural form of MCP-1/JE secreted by thymic epithelial cells. The 30 kDa glycosylated form of MCP-1 shows lower specific chemotactic activity (CA) for both lymphocytes and monocytes than the 6-7 kDa unglycosylated form of MCP-1.

Amino Acid Sequence↗
PubMed1996

[Analysis of chemokine (S) produced by mouse thymic stromal cell lines].

By using Boyden Chamber and PACS methods, we analysed the chemotactic activity of five mouse thymic stromal cell (MTSC) lines' culture supernatant for neutrophil, monocyte/macrophage and lymphocyte, and the phenotype of the attracted lymphocyes, MTEC 1, MTEC 2, MTEC 3, MTEC 5 are mouse thymus epithelial cell lines. MTDC 4 is a mouse thymus dendritic cell line. The results indicate that all of the five MTSC supernatants have chemotactic activity for the target cells mentioned above but in different degree. Chemokines produced by the MTSC cells can be classified into three categories: (1) Chemokines produced by MTEC 1 and MTEC 2 are more potent for the attraction of neutrophils and lymphocytes. (2) MTDC 4 derived chemokines are highly potent for the attraction of monocytes/macrophages. (3) Chemokines produced by MTEC 3 and MTEC 5 are equally attractive to neutrophils, lymphocytes and monocytes/macrophages. Most of the MTSC-SN are more potent for the migration of B lymphocyte than for T lymphocyte. The MTSC-SN exhibits higher chemotactic activity to CD4-CD8+ T cell subset than to CD4+CD8-T cell subset. The characterization of chemokines in MTSC-SN will benefit the finding of new chemokines and the analysis of the mechanism of thymus homing.

Animals↗
PubMed1996

[CD4-CD8- to CD4-CD8+ transition induced by anti-CD3 mAb in vitro cell culture system].

In our experiments, we have observed the effect of anti-CD3 mAb in inducing the differentiation of CD4-CD8- (double negative, DN) thymocytes into CD4+ CD8+ (double positive, DP) cells in an in vitro cell culture system including IL-7 for maintaining the growth of TN thymocytes. When TN thymocytes were stimulated by immobilized anti-CD3 mAb for 3 days, CD4-CD8+ cells generated, which were mostly immediate precursors of CD4+CD8+ thymocytes according to their surface TCR beta expression. The transition from DN to DP thymocytes accompanied with downregulation of interleukin 2 receptor (IL-2 R) alpha chain, and the TCR alpha beta-CD3 expression induced by IL-7 was also inhibited. Anti-CD3 mAb was effective only before the appearance of functional TCR-alpha beta-CD3 complex. Taking together, the results strongly suggest that anti-CD3 mAb induced DN thymocyte defferentiation is through the pre-TCR complex.

Animals↗
PubMed1995

Two-stage orchiopexy with laparoscopic clip ligation of the spermatic vessels in prune-belly syndrome.

A 1-year-old boy with prune-belly syndrome underwent unilateral laparoscopic clip ligation of the spermatic vessels with the hope of developing vasal collateral circulation. Six months later, the patient underwent ipsilateral second-stage orchiopexy on the right testis after division if the ligated spermatic vessels and contralateral Fowler-Stephens orchiopexy on the left testis in combination with major urinary tract reconstructions and abdominoplasty. For the following 1-year period, both testes were growing and comparable in size.

Cryptorchidism↗
PubMed1995

Pollakiuria: extraordinary daytime urinary frequency a common problem in pediatric practice.

Forty-eight children (28 males and 20 females) with acute onset of isolated daytime urinary frequency were retrospectively reviewed. Their age at the onset of symptom ranged from 4 to 7.8 years (median 6.3 years). Clinical evaluations by noninvasive means are completely normal in all patients. Treatment with anticholinergics or antibiotics did not relieve the symptom. In all patients, urinary frequency was resolved spontaneously after an average of 1.8 months from time of onset. There was no particular relationship between the season and the occurrence of the symptoms. Although the actual cause of pollakiuria is still not known, some kinds of psychophysiologic reaction has been implicated. In only 19 out of 48 patients, the possible trigger factor could be obtained. It should be emphasized that this clinical entity is a benign, self-limited situation that requires no invasive investigation or management other than reassurance.

Child↗
PubMed1995

Epizootic of low-virulence hepatotropic murine hepatitis virus in a nude mice breeding colony in Taiwan.

A natural outbreak of mouse hepatitis virus infection developed in a breeding colony of nude mice in Taiwan. The outbreak was unique in that morbidity was high in both adult and suckling mice, but only sucklings died. In contrast, all suckling heterozygous (nu/+) mice survived, and no lesions were found in adult female heterozygous (nu/+) mice. Adult male nude mice had chronic, active, necrotizing hepatitis with syncytial giant cells, but no lesions were detected in other tissues. Immunohistochemistry with anti-A59 and anti-JHM serum revealed mouse hepatitis virus antigen in the liver of infected adult and suckling nude mice, although less intensively in the kidney of adult nude mice. Suckling BALB/c mice inoculated with filtrates of the liver of adult nude mice developed hepatitis similar to that in the naturally infected nude mice. Virus was isolated by inoculating cell-free liver filtrate from infected adult nude mice onto 3T3 cells. Electron microscopy of purified virus revealed 100-nm-diameter enveloped particles with characteristic petal-shaped surface projections. We conclude that the outbreak was caused by a weakly virulent, highly hepatotropic murine hepatitis virus.

Animals↗
PubMed1995

[Excitation of hypothalamic nucleus arcuatus neuron induced decrease of plasma sialic acid level in rats].

The effect of sodium glutamate (Glu) on plasma sialic acid (SA) level was studied by means of microinjection into the nucleus arcuatus (ARC) and ultraviolet spectrophotometry. The results indicate: (1) The plasma SA level was significantly decreased after microinjection of Glu into the ARC (P < 0.01). With increasing Glu concentration, the onset of the decrease occurred earlier. (2) When Glu was microinjected into ARC after intraventricular injection of apomorphine, the plasma SA level was significantly decreased (P < 0.01) and the time required to cause the decrease was shortened. (3) When Glu was microinjected into ARC after intraventricular injection of spiperone, no change was found in the plasma SA level (P > 0.05). The above results suggest that the mechanism underlying the decrease of plasma SA level is probably related to modulated dopamine (DA) release of hypothalamic dopaminergic neurons by DA-D2 receptor.

Animals↗
PubMed1994

Effects of green tea and black tea on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone bioactivation, DNA methylation, and lung tumorigenesis in A/J mice.

Previous studies in our laboratory showed that decaffeinated green tea and black tea extracts inhibited 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced tumorigenicity in A/J female mice. In order to understand the mechanism of the inhibitory action, we examined the effects of decaffeinated green tea, black tea, and tea components on the metabolic activation of NNK in vitro and in vivo in this animal model. When added to incubation mixtures containing mouse lung microsomes, decaffeinated green tea and black tea extracts and their fractions, at concentrations up to 0.4 mg/ml, inhibited NNK oxidation and NNK-induced DNA methylation. Among the tea components examined, (-)-epigallocatechin-3-gallate was the most potent inhibitor with 50% inhibitory concentrations of about 0.12 mM for both NNK oxidation and DNA methylation. At these concentrations, (-)-epigallocatechin-3-gallate inhibited the catalytic activities of several P450 enzymes and was more potent against P450 1A and 2B1 than 2E1. When decaffeinated green or black tea extracts were given to female A/J mice as the sole source of drinking fluid before an i.p. injection of NNK (100 mg/kg body weight), a statistically significant inhibition of lung DNA methylation, however, was not observed, although a significant reduction in lung tumor multiplicity was observed. The results suggest that, although inhibition of the metabolic activation of NNK and the subsequent DNA alkylation by tea extracts can be demonstrated in vitro, this mechanism may not be important for the inhibitory action of tea against lung tumorigenesis.

Animals↗
PubMed1994

[Cytokine production by MTSC 4 cells, an established mouse thymic dendritic cell line].

The cytokine production by MTSC 4 cells, a murine thymic dendritic cell line established in our laboratory, has been investigated. Without exogenous stimulation, the MTSC 4 cells constitutively produce multiple types of cytokines, including IL-1, IL-6, IL-7, CSF, IFN and Chemotactic factor (CF). Of which, IL-6 and IFN were abundant: IL-1 and Chemokine, moderate: IL-7 and CSF at low level. MTSC4 cells could not produce detectable either IL-3 of TNF alpha. The establishment of MTSC 4 may be useful in the analysis of the mechanism of thymus selection, and in the study of the network regulation of autocrined cytokines.

Animals↗
PubMed1994

[Functional roles of LFA-1 involved in signal transduction for thymocyte activation].

The biological significance of the signals triggered by the interaction of cell surface expressed LFA-1 and ICAM-1 has been investigated in Con A and immobilized anti-CD3 mAb stimulated cultures. When added at the beginning of activation in the presence of Con A, soluble anti-LFA-1 and anti-ICAM-1 mAbs could strongly inhibit cell proliferation. Such inhibitory effect was also exhibited in the proliferative response of thymocytes to immobilized anti-CD 3 mAb activation. However, the soluble anti-LFA-1 mAb was unable to inhibit the proliferation of primed thymocytes preactivated with Con A for 24 h or of IL-1 + IL-2 activated fresh thymocytes. Anti-LFA-1 mAb could profoundly inhibit Con A-induced thymocytes to produce IL-2 and IL-6 and to reduce IL-2 receptor expression. By contrast, anti-LFA-immobilized on plastic plates together with immobilized anti-CD 3 mAbs or CD 3 cross-linking with LFA-1 by secondary antibodies resulted in an enhanced activation signals for thymocytes to proliferate compared with that activated by anti-CD 3 alone. Thus, mAb to LFA-1 is a functional molecule for thymocyte activation, mediating signals contributed to very early phases of signal transduction through TCR/CD 3 pathway, and that LFA-1 might provide a costimulatory signal for expression of IL-2 R and IL-2 production.

Animals↗
PubMed1994

[Role of LFA-1/ICAM-1 in the activation of murine thymocytes stimulated by Con A].

The biological significance of the signals triggered by the interaction of cell surface expressed LFA-1 and ICAM-1 has been investigated in Con A stimulated murine thymocytes. Addition of anti-LFA-1 or/and anti-ICAM-1 McAb to the thymocyte culture in the presence of Con A, the cell proliferation was profoundly inhibited. Such inhibitory effect was more significant by the addition of anti-LFA-1 than by the addition of anti-ICAM-1 McAb. FACS analysis revealed that the proliferation of CD8+ T cells was more sensitive to the inhibitory effect of anti-LFA-1 McAb than did the proliferation of CD4+ T cells. The anti-LFA-1 McAb imposed inhibitory effect, however, could be reversed by the supplementation of IL-2 in the initiation of the culture. The proliferation of cultured Con A activated T blast cells could no longer be inhibited by the addition of anti-LFA-1 McAb. Furthermore, neither anti-LFA-1 nor anti-ICAM-1 McAb could block PMA+A23187 induced thymocyte proliferation. The results imply that the ligand-receptor pair of LFA-1-ICAM-1 molecules also takes part in the early events of Con A activated signal transduction pathway which leads to the proliferation of thymocytes.

Animals↗
PubMed1994

Increased production of interleukin 4 in children with simple idiopathic nephrotic syndrome.

Sera and peripheral blood mononuclear cells (PBMC) were collected from 42 children with simple idiopathic nephrotic syndrome (INS) aged from 1.5 to 14 years and 28 age and sex-matched healthy children. The levels of IgE in serum and interleukin 4 (IL-4) in supernatant of PHA-activated PBMC were tested by ELISA. A significantly high incidence of allergic diseases was noted in INS children and their first-degree relatives, and there was a close association between atopy and INS. Besides, the levels of IgE and IL-4 were increased in nephrotic state (P < 0.001 both). IgE normal and IL-4 slightly lower in remission state (P < 0.2, P < 0.01 respectively). A positive correlation was noticed between IL-4 and IgE, and between IL-4 and 24-hour proteinuria (r = 0.472, r = 0.562; P < 005, P < 0.01 respectively). These showed a close association between atopy and INS. Both IL-4 and IgE, the important mediators in atopy, showed abnormal change in patients. The increased IL-4 production of T cells might account for the elevated serum IgE level. IL-4 may have a pathogenetic role in INS, but it still remains speculative.

Adolescent↗
PubMed1994

Osteogenesis imperfecta in a family.

Osteogenesis imperfecta (OI) is a rare, inherited condition in which not only the bones are abnormally brittle but also abnormalities in the ligamentous structures, of the eye, ear and skin coexist. Three members of the same family experienced the pathologic fractures with squaring deformity, but no blue sclerae or deafness. They presented with a relatively benign course treated conservatively.

Adult↗