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Biomedical subjects

T C Chen

Publications and source records attributed to T C Chen.

At least 127 records · Page 7Linked to original sources
PubMed1997

Soluble TNF-alpha receptors are constitutively shed and downregulate adhesion molecule expression in malignant gliomas.

The regulation of adhesion molecule expression in malignant gliomas by tumor necrosis factor-alpha (TNF) and soluble TNF receptors (TNFR) was examined in the malignant glioma cell line A-172 and in 2 primary glioblastoma cell cultures (LA-492 and LA-567). A-172 cells expressed only the p55 TNF receptor transcripts and protein. The 2 primary cell cultures expressed both the p55 and p75 TNF receptors. In A-172 cells and in 1 of 2 primary glioma cell cultures, TNF upregulated the expression of ICAM-1 and VCAM-1, A-172 and both primary glioma cultures also shed their TNF receptors in the absence of activation by stimulating agents. Soluble p55 (sp55) receptors, but not soluble p75 (sp75) receptors, were found to reduce the TNF induced VCAM-1 and ICAM-1 expression in both the glioma cell line and the primary cell culture. Immunostaining of malignant glioma sections confirmed the presence of soluble TNFR and adhesion molecule expression in glioma cells in situ. These data suggest that soluble TNF receptors may play a role in the mechanism by which malignant gliomas downregulate the effects of infiltrating immune-competent cells.

Cell Adhesion Molecules↗
PubMed1997

Pediatric intracranial hemangioendotheliomas: case report.

OBJECTIVE AND IMPORTANCE: Intracranial hemangioendotheliomas are rare lesions, especially in the pediatric age group. Recognizing hemangioendotheliomas as a differential in intracranial tumors of vascular origin is important; complete excision results in a cure, and medical therapy for those lesions that are not resectable produces long-term survival. CLINICAL PRESENTATION: We report two patients, a 7-year-old female patient with a lesion in the right gasserian ganglion and a 3-month-old male patient with a cervicomedullary junction tumor. INTERVENTION: The 7-year-old underwent a gross total removal with no recurrence. The 3-month-old underwent a partial resection followed by treatment with interferon alpha-2a, with a decrease in the size of the residual tumor. Both patients have been followed for more than 4 years without a recurrence or progression of the tumor. CONCLUSION: Hemangioendotheliomas are fairly indolent tumors and may be treated with complete surgical resection, resulting in a cure. In cases in which complete tumor removal is not possible, adjunctive therapy with interferon alpha-2a may control residual tumor growth.

Brain Neoplasms↗
PubMed1997

Histopathology and pathobiology of hepatotropic virus-induced liver injury.

The present report concerns current knowledge regarding immunopathogenesis that can be applied in the interpretation of histopathological changes in acute and chronic viral hepatitis. The histopathological features of viral hepatitis have not been changed and light microscopic examination remains essential for making a diagnosis and classification of chronic hepatitis and for the provision of objective parameters on grading and staging. However, new understanding and knowledge of viral pathogenesis, host immune responses, the biological behaviour of the causative viral agents and, in particular, viral interference in multiple hepatotropic viral infections must be taken into consideration in the interpretation of histopathological and immunopathological findings of liver tissues. This report also presents some histopathological analyses on multiple hepatotropic viral infections. It can be concluded that the diagnostic histological criteria for acute hepatitis remain applicable in such settings. However, the cause of acute flare up in chronic hepatitis could not be determined without clinical, virological and serological information. Routine histopathology cannot distinguish a new infection from an acute exacerbation due to a high level of viral replication or mutant virus. A repertoire of immunocytochemical stainings for viral antigens is helpful, but caution must be exercised in suggesting a specific viral aetiology due to the fact that suppression of pre-existing viral antigens can be pronounced when the new or concurrent infection is hepatitis C virus related.

Animals↗
PubMed1997

Expression of integrin subunits and CD44 isoforms in psoriatic skin and effects of topical calcitriol application.

Increasing evidence suggests involvement of integrins and CD44 isoforms in the pathogenesis of psoriasis, contributing to uncontrolled keratinocyte proliferation, neovascularization, and invasion of inflammatory cells. We have analyzed immunohistochemically in situ expression of integrins (CD29, CDw49b, CDw49c, CDw49e, CDw49f) and CD44 isoforms (CD44 standard, CD44 var/v6, CD44 v10) on frozen sections of normal and psoriatic skin (nonlesional skin, lesional skin before and along with topical calcitriol treatment). We did not observe visual changes of immunoreactivity in normal as compared to nonlesional psoriatic skin, while the staining pattern of CDw49c, CDw49f, and CD29 was severely altered in untreated lesional psoriatic skin. Most markedly, CDw49c, CDw49f, and CD29 were focally upregulated in suprapapillar epidermal compartments of lesional psoriatic skin, a staining pattern that is in accordance with the phenomenon that was described by Pinkus as "squirting papilla". Additionally, an increased proportion of inflammatory and endothelial cells revealed immunoreactivity for CD44(std.) in untreated lesional psoriatic as compared to nonlesional psoriatic or normal skin. After 8 weeks of topical calcitriol treatment (15 micrograms/g ointment), the staining pattern for CDw49c, CDw49f and CD29 was markedly changed in epidermis of lesional psoriatic skin, reverting to the staining pattern characteristic for the nonlesional psoriatic or normal human skin, although epidermal expression of CDw49f was still upregulated and CDw49e-, CDw49f-, CD29-, and CD44(std.)-immunoreactive inflammatory and endothelial cells were still to be found in the dermal compartment.

Administration, Topical↗
PubMed1997

Novel and frequent mutations of hepatitis B virus coincide with a major histocompatibility complex class I-restricted T-cell epitope of the surface antigen.

We examined the full-length hepatitis B virus (HBV) envelope (surface antigen or HBV small surface antigen [HBsAg]) sequences of 12 different liver samples from 10 different hepatoma-containing chronic carriers. Surprisingly, novel and frequent mutations occurred predominantly at amino acids 40 and 47 of HBsAg, in addition to within a known protective B-cell epitope (so-called group a determinant of HBsAg 124-148). Approximately 58% of chronic carriers contain mutations at the group a determinant. The mutation frequency at the hotspot codons 40 and 47 is approximately 83%, 1 order of magnitude higher than at the known polymorphic sites of subtype-specific determinants at codons 122 and 160, which is approximately 4%. This new mutational domain is found to coincide with a major histocompatibility complex class I-restricted T-cell epitope. The potential biological significance of this novel mutation in the immunopathogenesis of HBV chronic carriers is discussed.

Adult↗
PubMed1997

Calcium absorptive effects of vitamin D and its major metabolites.

The absorptive response to graded doses of vitamin D3, 25(OH)D, and 1,25(OH)2D was measured in healthy adult men after treatment periods of eight, four, and two weeks, respectively. While no relationship was found between baseline absorption and serum vitamin D metabolite levels, all three vitamin D compounds significantly elevated 45Ca absorption from a 300 mg calcium load given as part of a standard test meal. 1,25(OH)2D was active even at the lowest dose (0.5 microgram/day), and the slope was such that doubling of absorption would occur at an oral dose of approximately 3 micrograms/day. 25(OH)D was also active in elevating absorption and did so without raising total 1,25(OH)2D levels. On the basis of the dose response curves for 1,25(OH)2D and 25(OH)D, the two compounds exhibited a molar ratio for physiological potency of approximately 100:1. The absorptive effect of vitamin D3 was seen only at the highest dose level (1250 micrograms, or 50,000 IU/day) and was apparently mediated by conversion to 25(OH)D. Analysis of the pooled 25(OH)D data from both the 25(OH)D- and vitamin D3-treated groups suggests that approximately one eighth of circulating vitamin D-like absorptive activity under untreated conditions in winter may reside in 25(OH)D. This is a substantially larger share than has been predicted from studies of in vitro receptor binding.

Absorption↗
PubMed1997

Tuberculoma of the liver presenting as a hyperechoic mass on ultrasound.

An unusual case of hepatic macronodular tuberculoma is presented. As demonstrated by CT, the tuberculoma replaced the entire lateral segment of the left lobe of liver and resembled an infiltrative tumour. On ultrasound, the tuberculoma presented as a hyperechoic lesion, in contrast to a round hypoechoic mass which is usually seen in this condition. Hepatic macronodular tuberculomas are not uncommonly misdiagnosed as primary or secondary liver tumours by imaging studies, and the definite diagnosis is usually established by liver biopsy. The prognosis of hepatic macronodular tuberculoma is usually very good with effective treatment.

Adult↗
PubMed1997

Topical calcitriol (1,25-dihydroxyvitamin D3) treatment of psoriasis: an immunohistological evaluation.

The potent calciotropic hormone calcitriol (1,25-dihydroxyvitamin D3, 1,25(OH)2D3) has been shown to be very effective and safe in the topical treatment of psoriasis. In vitro, 1,25(OH)2D3 inhibits proliferation and stimulates differentiation of human keratinocytes. Increasing evidence suggests an immunoregulatory function of this potent steroid hormone. To further characterize the biological effects of topical calcitriol treatment in psoriasis, we have analyzed immunohistochemically the expression of markers for epidermal proliferation (proliferating cell nuclear antigen=PCNA) and differentiation (transglutaminase K, involucrin, cytokeratin 16), as well as inflammation (CD1a, 55 kDa TNF-receptor, NAP-1/IL-8) in calcitriol-treated psoriatic skin in situ. Our findings strongly support the hypothesis that calcitriol modulates keratinocyte proliferation/differentiation as well as inflammation in human skin in vivo. The immunoreactivity of markers for epidermal proliferation and differentiation, as well as of CD1a and NAP-1/IL-8, changed after 8 weeks of calcitriol treatment almost completely to the pattern characteristic for non-lesional psoriatic skin, while a large number of 55 kDa TNF-receptor positive cells could be found in the dermal compartment.

Administration, Topical↗
PubMed1997

Ménétrier's disease: a new variant with duodenal involvement.

Ménétrier's disease is a rare cause of hypertrophic gastropathy, usually confined to gastric body and fundus, which is characterized by giant rugae, hypoalbuminemia, and foveolar hyperplasia. The etiology of this disease is still unknown. We report a case of a 74-yr-old man who had dyspepsia, hypoalbuminemia, weight loss, and diffuse polypoid, nodular lesions affecting the whole stomach and proximal duodenum on gastroscopy and barium meal study. The histology of gastric and duodenal mucosal lesions fulfilled the diagnosis of Ménétrier's disease, that was not described to involve duodenum in the literature. The disease resolved clinically, endoscopically, and pathologically after therapy with famotidine for 3 months. We speculated that extensive pyloric metaplasia and then foveolar hyperplasia of duodenum in this patient might be a variant of Ménétrier's disease with favorable clinical course.

Aged↗
PubMed1997

[Cognition, needs, satisfaction, and emotional responses for home care in bone marrow transplantation patients].

Bone marrow transplantation (BMT) is an aggressive treatment which can induce considerable physical and psychological stresses. Patients face various problems in self care and psychological adjustment after discharge from the hospital. The purpose of this study was to explore the cognition, needs, satisfaction, and emotional responses toward home care in BMT patients and the factors influencing them. Forth BMT patients were enrolled from the outpatient clinic of BMT in a medical center. A descriptive research design was adopted. Cognition, needs, satisfaction, anxiety and depression for home care in these patients were collected by questionaires. The results showed that BMT patients had inadequate knowledge about how to care for themselves at home. High need and low satisfaction on disease adjustment and home care were found in these patients. All patients experienced anxiety and depression. Occupation, education, and socioeconomic status were found to affect patient's cognition. Religious belief influenced needs and satisfaction for home care in these patients. Sex and social-economic status emotional reaction of patients. This study will help health personnel understand the cognition, needs and satisfaction for home care in BMT patients. It can be used as a reference for organizing discharge plan and extending the continuity of care for BMT patients.

Adolescent↗
PubMed1996

p53 mutations in gastric cancers from Taiwan.

Mutations of the p53 gene were investigated in 80 surgical specimens of primary gastric cancer by polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis. Mutations were detected in 18 tumors (22.5%) and localized to exons 5, 7 and 8. Mutations did not follow a random distribution among different subtypes, but instead clustered in the group of papillary adenocarcinomas, in which 7/12 (58.3%) cases were mutated. Positivity for p53 mutation was significantly higher in intestinal-type (37.5%) than in diffuse-type carcinomas (12.5%). These results suggest that gene alterations of p53 are not rare and may participate in the carcinogenesis of intestinal-type carcinomas of the stomach. Twenty of 21 p53 mutations were represented by single nucleotide changes, mostly missense mutations (19 events) and one nonsense mutation. Transversional mutations constitute the majority of p53 mutations (65%) and only 20% of mutations show G:C to A:T transitions. It is possible that the etiologies of gastric cancer in different geographical areas are different.

Adult↗
PubMed1996

Regulation of the last two enzymatic reactions in cholesterol biosynthesis in rats: effects of BM 15.766, cholesterol, cholic acid, lovastatin, and their combinations.

The Smith-Lemli-Opitz syndrome is a common inherited birth disorder caused by markedly reduced 7-dehydrocholesterol delta 7-reductase activity, the final enzyme in the cholesterol biosynthetic pathway. BM 15.766 (4-[2-[1-(4-chlorocinnamyl)piperazin-4-yl]ethyl]-benzoic acid) inhibits 7-dehydrocholesterol delta 7-reductase activity, reduces plasma cholesterol levels, and increases 7-dehydrocholesterol levels to reproduce the biochemical abnormalities of the syndrome in rats. Cholesterol, cholic acid, and lovastatin, alone or in combinations, were fed to rats given BM 15.766, and hepatic activities of the last two enzymes in the cholesterol biosynthetic pathway, lathosterol 5-dehydrogenase and 7-dehydrocholesterol delta 7-reductase, were measured. After feeding BM 15.766, hepatic 7-dehydrocholesterol delta 7-reductase activity decreased by 77% while lathosterol 5-dehydrogenase activity tended to increase, so that the ratio of 5-dehydrogenase to delta 7-reductase activities increased from 0.33 to 2.8. In BM 15.766-fed rats, treatment with cholesterol suppressed both 5-dehydrogenase and delta 7-reductase activities by 76% and 66%, respectively, and decreased the 5-dehydrogenase: delta 7-reductase activities ratio from 2.8 to 2.2. In contrast, treatment with cholic acid and BM 15.766 further inhibited delta 7-reductase activity by 67% without changing significantly the 5-dehydrogenase activity that had increased the ratio to 5.5. Combining BM 15.766 with lovastatin increased 5-dehydrogenase activity fivefold but did not change delta 7-reductase activity, raising the ratio to 14.3. In BM 15.766-treated rats, the first and last two enzymatic reactions in the cholesterol biosynthetic pathway catalyzed by 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, lathosterol 5-dehydrogenase, and 7-dehydrocholesterol delta 7-reductase are down-regulated by cholesterol. Thus, only cholesterol and not cholic acid or lovastatin could reduce elevated plasma 7-dehydrocholesterol levels induced by BM 15.766.

Animals↗
PubMed1996

Management of perineal endometriosis.

OBJECTIVE: To demonstrate the appropriate diagnosis and management of perineal endometriosis. METHOD: Six patients with perineal endometriosis were diagnosed according to their clinical symptoms and signs which included cyclic perineal pain and a tender perineal mass coinciding with the menstrual cycle. Diagnostic tools used included ultrasonography, computerized tomography, fine needle aspiration cytology and laparoscopy. Management comprised both surgical and medical treatment. Postoperative follow-up was carried out at 3-monthly intervals. RESULTS: All six patients were cured following surgical excision of the endometrioma. CONCLUSION: A detailed history, thorough pelvic examination and sonographic investigation are essential in diagnosing perineal endometriosis. The role of other diagnostic tools remains controversial. Treatment of extrapelvic endometriosis includes surgical intervention and hormonal suppression. If hormonal suppression fails, surgical excision of the perineal endometrioma should be carried out.

Adult↗
PubMed1996

Long-term results of trabeculectomy in eyes that were initially successful.

A number of published case series provide short-term and intermediate success rates for the surgical treatment of glaucoma with trabeculectomy. There is little information, however, regarding long-term outcomes that extend beyond 10 years. Therefore, we conducted a retrospective study to determine the long-term outcome of eyes that had successful trabeculectomy surgery at 1 year (IOP < 21 mmHg, or lowering by 33% if preoperative IOP was < 21 mm Hg) and had been followed up for at least 10 years. We found 40 such eyes. With respect to IOP control, 83% were still considered to be successful at 5 years, 73% at 10 years, but only 42% at 15 years. Ten percent required additional glaucoma surgery by 5 years, 25% by 10 years, and 58% by 15 years. Forty percent of the eyes had cataract surgery by the time of the last follow-up examination. It appears that there is a significant late failure rate of trabeculectomy in eyes that were initially successful.

Adolescent↗
PubMed1996

Cellular uptake and transport of methylprednisolone at the blood-brain barrier.

Methylprednisolone (MP) is one of the most widely used neuroprotective drugs in neurosurgery. Our knowledge of its pharmacokinetics in the brain and, in particular, whether it can penetrate the blood-brain barrier (BBB) and act in the brain parenchyma is still limited. In this study, we used a vascular brain perfusion technique in guinea pigs, combined with a capillary depletion method, to determine brain uptake and transport of MP at the BBB. 3H-Labeled MP was delivered to the brain by carotid arterial infusions lasting from 1 to 10 minutes; the effects of plasma protein binding, different concentrations of MP, and the glucocorticoid receptor inhibitor, RU486, were examined. The existence of a transport system was inferred from the observation that the volume of distribution of MP in the brain after perfusion exceeded by 2.6 to 6.3 times the plasma volume of the cerebrovascular space marker, sucrose. The rates of undirectional [3H]MP blood-to-brain transport of 0.5 to 0.7 microliters per minute per gram indicated significant but slow transfer. MP available for BBB transport was not restricted to its free plasma fraction but, instead, included the albumin- and globulin-bound fractions. A portion of steroid remained concentrated (sequestered) by the capillary endothelium, and from there, the label was distributed into brain parenchyma. Both MP binding and transport at the BBB exhibited saturable kinetics. RU486 produced an inhibition of MP BBB transport and binding with an affinity that seemed to be 30 to 60% higher than that of the steroid itself. We concluded that MP first binds to the brain capillaries and then crosses the BBB at a low rate, most likely by using a saturable mechanism that may involve a cytoplasmic endothelial glucocorticoid receptor.

Animals↗