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Biomedical subjects

T C Chen

Publications and source records attributed to T C Chen.

At least 19 recordsLinked to original sources
PubMed2002

Nuclear beta-catenin expression is closely related to ulcerative growth of colorectal carcinoma.

Although most colorectal cancer develops based on the adenoma-adenocarcinoma sequence, morphologically, colorectal cancer is not a homogeneous disease entity. Generally, there are two distinct morphological types: polypoid and ulcerative colorectal tumours. Previous studies have demonstrated that K-ras codon 12 mutations are preferentially associated with polypoid growth of colorectal cancer; however, little is known about the molecular mechanism that determines ulcerative growth of colorectal cancer. beta-catenin complex plays a critical role both in tumorigenesis and morphogenesis. We examined the differential expression of beta-catenin and its related factors among different types of colorectal cancer in order to determine any relationship with gross tumour morphology. Immunohistochemical staining of beta-catenin, E-cadherin and MMP-7 was performed on 51 tumours, including 26 polypoid tumours and 25 ulcerative tumours. Protein truncation tests and single-strand conformational polymorphism for mutation of the adenomatous polyposis coli tumour suppressor gene, as well as single-strand conformational polymorphism for the mutation of beta-catenin exon 3 were also done. Nuclear expression of beta-catenin was observed in 18 out of 25 (72%) cases of ulcerative colorectal cancer and seven out of 26 (26.9%) cases of polypoid colorectal cancer. A significant relationship of nuclear beta-catenin expression with ulcerative colorectal cancer was found (P<0.001). However, this finding was independent of adenomatous polyposis coli tumour suppressor gene mutation and E-cadherin expression. Together with previous data, we propose that different combinations of genetic alterations may underlie different morphological types of colorectal cancer. These findings should be taken into consideration whenever developing a new genetic diagnosis or therapy for colorectal cancer.

Adenomatous Polyposis Coli↗
PubMed2001

Stabilization of an elevated heavy metal contaminated site.

Heavy metal contamination is a common problem that is encountered at many uncontrolled sites. Immobilization is seen as a promising technology for heavy metal remediation. Here, we report a remediation case study of an elevated and multi-metal contaminated site containing Cd, Cu, Ni, Pb, and Zn. In a laboratory test, when the soil was stabilized with reagent grade stabilizers (CaHPO(4) and CaCO(3)), the toxicity characteristic leaching procedure (TCLP) extractable concentrations of Cd, Cu, Pb, and Zn were reduced by more than 87%. The greatest reduction was shown with Pb (99.8%). In the field, Ca(H(2)PO(4))(2) due to lower cost and higher solubility replaced CaHPO(4). The TCLP results of the field treatment showed that the extractable concentrations of Cd, Cu, Pb, and Zn were significantly reduced after 30 days of stabilization. The reduction ratios were 98% (Cd), 97% (Cu), 99% (Pb), and 96% (Zn). Although, the reduction ratio of Ni was only 65%, the average extractable concentration was still less than 4.0mg/l. The percent reduction can, therefore, be considered reasonable. The significant reduction of extractable metal concentrations showed that the stabilizers, a combination of Ca(H(2)PO(4))(2) and CaCO(3), successfully immobilized heavy metals on the site.

Carbonates↗
PubMed2001

On-line monitoring of trihalomethanes in drinking water using continuous-flow purge and cryofocusing gas chromatography-mass spectrometry.

A continuous-flow purge-and-trap-GC-MS system was developed for on-line monitoring of THMs (trihalomethanes) in drinking water. Three systems with different traps and purging flow-rates are discussed. In order to minimize interference from water vapor, total purge gas volume and injection temperature were controlled during analysis. Shorter sample concentration time and GC separation time reduced total cycle time to less than 5 min. The detection limits of the system could be lowered to 10 ppt, 25 ppt, 40 ppt, and 50 ppt (w/w) for CHCl3, CHCl2Br, CHClBr2, and CHBr3, respectively. This system could detect changes in sample concentration when applied to the on-line monitoring of THMs in drinking water.

Gas Chromatography-Mass Spectrometry↗
PubMed2001

Drop metastasis from sinonasal undifferentiated carcinoma: clinical implications.

STUDY DESIGN: The first reported case of multiple intradural, extramedullary spinal metastasis from sinonasal undifferentiated carcinoma is presented. OBJECTIVES: To elucidate the mechanisms by which metastatic disease invades the spinal axis, and to discuss the possibility of spinal drop metastasis from head and neck tumors that invade the dura. SUMMARY OF BACKGROUND DATA: Sinonasal undifferentiated carcinoma is a rare yet aggressive neoplasm of the upper airways and anterior skull base. This neoplasm is known to invade the cranial vault and brain locally. However, it has not previously been reported to seed the cerebrospinal fluid or result in drop metastasis. Such drop metastasis may result in significant neurologic deficit if not diagnosed and treated in a timely manner. METHODS: This report is based on a single patient treated by a multidisciplinary team from the departments of neurosurgery, otolaryngology, and radiation oncology at the University of Southern California School of Medicine. RESULTS: This patient initially underwent resection and local radiation therapy for sinonasal undifferentiated carcinoma of the anterior skull base. At the time of surgery, the tumor was noted to violate the dura and arachnoid along the subfrontal plane. At 11/2 years after the initial treatment, a bandlike distribution developed at T2 as well as paresthesias and numbness below that level. Imaging of the spine showed an intradural, extramedullary tumor at T2 consistent with a schwannoma or meningioma. The patient underwent a laminectomy and tumor resection, which showed poorly differentiated sinonasal carcinoma. Local radiation therapy was administered, and the patient experienced complete recovery of neurologic function. Bilateral leg pain and weakness developed 14 months later. Magnetic resonance imaging of the spine showed a new intradural, extramedullary lesion at T12, remote from the first lesion. This second metastasis was managed with surgical resection and adjuvant radiation therapy. CONCLUSIONS: This is the first reported case of a sinonasal carcinoma leading to intradural extramedullary metastasis. The primary tumor likely seeded the cerebrospinal fluid, thus resulting in drop metastasis. Patients with sinonasal undifferentiated carcinoma that invades the dura should be monitored closely for evidence of metastasis before symptoms develop.

Carcinoma↗
PubMed2001

25-hydroxyvitamin D-1alpha-hydroxylase in normal and malignant colon tissue.

Vitamin D affects calcium metabolism and prevents proliferation of colon cells in vitro. In human beings the main circulating form of vitamin D is 25-hydroxyvitamin D; to regulate calcium homoeostasis, this form must be converted to 1alpha, 25-dihydroxyvitamin D by 1alpha-hydroxylation in the kidney with 25-hydroxyvitamin D-1alpha-hydroxylase. Cultured transformed colon cancer cells can convert 25-hydroxyvitamin D(3) to 1alpha,25-dihydroxyvitamin D(3). We identified messenger RNA (mRNA) for 25-hydroxyvitamin D-1alpha-hydroxylase in normal colon tissue and in malignant and adjacent normal colon tissue. These findings support the notion that vitamin D might have a role in cell growth regulation and cancer protection, and might be the explanation for why the risk of dying from colorectal cancer is highest in areas with the least amount of sunlight.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed2001

Genome-wide hypomethylation in hepatocellular carcinogenesis.

Aberrant genome-wide hypomethylation has been thought to be related to tumorigenesis. However, its mechanism and implications in hepatocellular carcinogenesis remain to be elucidated. Samples of hepatoma (hepatocellular carcinoma, HCC) and paired non-HCC liver tissues were obtained from 17 HCC patients. Normal liver tissues obtained from three individuals were used as controls. Compared with the paired non-HCC liver tissues, genome-wide 5-methylcytosine content in HCC was reduced in all of the tested HCC samples (P < 0.001). Conversely, genome-wide 5-methylcytosine content did not significantly differ among normal, noncirrhotic, and cirrhotic liver tissues. Moreover, the degree of reduced DNA methylation was related to late histopathological HCC grade (P = 0.005) and large tumor size (P = 0.079). Compared with the paired non-HCC liver tissues, expression of DNA methyltransferases DNMT-1, DNMT-3A, and DNMT-3B and the DNA methyltransferase-like gene, DNMT-2, was up-regulated in 53, 41, 59, and 47% of the HCC samples, respectively. Surprisingly, small amounts of LINE-1 retrotransposon transcripts were detected in HCC and non-HCC as well as normal liver tissues, and the expression levels were not significantly different in HCC compared with the paired non-HCC or normal liver tissues. Of interest, the 3' ends of these LINE-1 transcripts were truncated. Our findings suggest that genome-wide hypomethylation in HCC is a continuing process that persists throughout the lifetime of the tumor cells rather than a historical event occurring in precancer stages or in cell origins for HCC. Up-regulation of DNA methyltransferases might simply be a result of increased cell proliferation in cancer. In addition, our results did not support the hypothesis of activation of transposable elements in HCC via genome-wide hypomethylation.

5-Methylcytosine↗
PubMed2001

Angiomyolipoma of the liver.

BACKGROUND AND OBJECTIVES: Angiomyolipoma is a rare benign tumor that occurs in the liver and other organs. We provide data on eight cases of hepatic angiomyolipoma, regarding clinical presentations, diagnoses, management, and prognosis. METHODS: A retrospective review of medical records of the eight patients with hepatic angiomyolipoma treated at the Chang Gung Memorial Hospital-Taipei between October 1988 and October 1999. RESULTS: Eight female patients with hepatic angiomyolipoma were identified, with ages ranging from 30 to 66 years (mean, 45.3 years). Abdominal pain was the most common symptom, occurring in six of eight patients (75%). Hepatocellular carcinoma was the most common preoperative diagnosis, occurring in three of eight patients (37.5%). Laparotomy was performed in seven of eight patients (87.5%). Among these seven patients, three patients (43%) received hepatic resection with 100% cure rate to date. One of the eight patients (12.5%) was closely follow up after diagnosis made by echo-guided needle biopsy. CONCLUSIONS: Hepatic angiomyolipoma is a rare and benign entity. It has a wide variation and poses a diagnostic challenge clinically, radiologically, and pathologically. Its prognosis is good regardless of management, including hepatic resection or conservative treatment after tissue biopsy by echo-guided needle. To alleviate the mass effect, surgical resection may be needed for hepatic angiomyolipoma in selected cases.

Abdominal Pain↗
PubMed2001

Observations on serum 25-hydroxyvitamin D and calcium concentrations from wild-caught and captive neotropical bats, Artibeus jamaicensis.

Most bats of the suborder Microchiroptera are nocturnal, actively avoid sunlight, and eat mineral-poor diets. In those bats previously studied with respect to mineral metabolism, extensive bone remodeling occurs, and it has been suggested that calcium has been an important constraint on reproduction. There have been no previous studies of vitamin D or its metabolites in microchiropteran bats with respect to calcium metabolism. Reported is the utilization of current advances for the determination of serum levels of the vitamin D metabolite 25-hyroxyvitamin D (25-OH-D) in a neotropical bat, Artibeus jamaicensis. Serum from wild-caught animals contained low levels of 25-OH-D (5.6 +/- 3.0 ng/ml, n = 8). Bats maintained on a vitamin-D-supplemented diet had higher serum 25-OH-D levels and when the diet containing vitamin D was discontinued, mean serum 25-OH-D levels declined significantly after 6 months. Serum calcium concentrations in wild-caught bats (8.5 +/- 0.4 mg%) showed very little variation and were not significantly different in any of the vitamin-D-supplemented animals. A pairwise correlation analysis between 25-OH-D and serum calcium levels revealed no linear correlation. The results indicate either that 25-OH-D does not appear to play a key role or that low levels of 25-OH-D may be adequate in regulating serum calcium levels in this bat.

25-Hydroxyvitamin D 2↗
PubMed2001

Hepatocellular carcinoma associated with focal nodular hyperplasia. Report of a case with clonal analysis.

We describe a hepatocellular carcinoma partially surrounded by focal nodular hyperplasia in a 65-year-old female patient. In order to clarify the relationship of the hepatocellular carcinoma and the adjacent focal nodular hyperplasia, clonal analysis was conducted. The clonal analysis was based on the methylation pattern of the polymorphic X-chromosome-linked androgen receptor gene (HUMARA). The allelic bands from the amplification of the focal nodular hyperplasia and of the hepatocellular carcinoma showed a significant reduction in the intensity of one of the two alleles as compared with two alleles of equal intensity in the buff coat after HhaI digestion, which indicated that these two parts were monoclonal. However, the inactivated allele in the focal nodular hyperplasia and that in the hepatocellular carcinoma were not identical. Therefore, the focal nodular hyperplasia and hepatocellular carcinoma probably derived from the clonal expansion of two different clones.

Aged↗
PubMed2001

Brimonidine 0.2% versus apraclonidine 0.5% for prevention of intraocular pressure elevations after anterior segment laser surgery.

OBJECTIVE: To compare the efficacy of brimonidine 0.2% with apraclonidine 0.5% in preventing intraocular pressure (IOP) elevations after anterior segment laser surgery. DESIGN: Double-masked, randomized clinical trial. PARTICIPANTS: Sixty-six patients underwent either laser peripheral iridotomy, argon laser trabeculoplasty, or neodymium:yttrium-aluminum-garnet laser capsulotomy. INTERVENTION: Eyes received either one drop of brimonidine 0.2% or apraclonidine 0.5% before laser surgery. MAIN OUTCOME MEASURES: Intraocular pressure, heart rate, and blood pressure were measured before laser surgery and at 1 hour, 3 hours, 24 hours, and 1 week after laser surgery. RESULTS: Before the laser treatment, 33 patients (50.0%) received brimonidine 0.2% and 33 patients (50.0%) received apraclonidine 0.5%. Eight of 33 patients (24.2%) in the brimonidine-treated group and 9 of 33 patients (27.3%) in the apraclonidine group had postoperative IOP increases of 5 mmHg or more. This was not statistically different (P = 0.80). By the time of last follow-up examination, 3 of 33 patients (9.1%) in the brimonidine-treated group and 3 of 33 patients (9.1%) in the apraclonidine group had IOP increases of 10 mmHg or more. This was also not statistically different (P > or = 0.95). The mean IOP reduction from baseline in the brimonidine group (-2.8 +/- 2.8 mmHg) was not statistically different (P = 0.55) compared with the mean IOP reduction in the apraclonidine group (-3.6 +/- 3.3 mmHg). There were no statistically significant changes in mean heart rate or blood pressure in either group except for a slight reduction in diastolic blood pressure at 1 hour (P = 0.005) in the brimonidine group (-5.2 +/- 7.4 mmHg) compared with the apraclonidine group (-0.2 +/- 6.4 mmHg). There were no clinically significant side effects noted in either group. CONCLUSIONS: A single preoperative drop of brimonidine 0.2% is as effective as apraclonidine 0.5% in preventing IOP elevation immediately after anterior segment laser surgery.

Adrenergic alpha-Agonists↗
PubMed2001

Follicular dendritic cell tumor of the liver: a clinicopathologic and Epstein-Barr virus study of two cases.

Two cases of hepatic follicular dendritic cell (FDC) tumor are described. Both patients were female, aged 57 and 51 years. They presented with epigastralgia or abdominal fullness and weight loss. The first patient refused surgical resection. She developed progressive polyclonal gammopathy and then bilateral purpura over the legs. Skin biopsy revealed leukocytoclastic vasculitis with granular vascular deposits of IgA and C3. The second patient had marked peripheral blood and tissue eosinophilia. The histological diagnosis was confirmed by positive staining for CD21 and CD23. The stromal lymphocytes were predominantly composed of CD3(+)and CD8(+) cells. In situ hybridization for EBER showed a positive nuclear signal in tumor cells but not in inflammatory cells. Polymerase chain reaction amplification for Exon 3 of the latent membrane protein-1 (LMP-1) gene showed a characteristic 30-bp deletion between nucleotides 168282 and 168253, corresponding to the B95-8 sequence. The unique clinicopathological features of our cases have not been reported for FDC tumors before. The clinical significance of the 30-bp deletion in Exon 3 of the LMP-1 gene in FDC tumor of the liver warrants further investigation.

Complement C3↗
PubMed2001

Intrahepatic cholangiocarcinoma with lymphoepithelioma-like component.

We present two cases of intrahepatic cholangiocarcinoma with lymphoepithelioma-like component. The patients included one woman and one man, aged 67 and 41 years, respectively. They presented with right upper quadrant pain and epigastralgia. Histologically, both tumors showed two distinct histological patterns with dense lymphoplasma cell infiltration. The first pattern was a well to moderately differentiated adenocarcinoma; the second component showed a feature similar to lymphoepithelioma-like carcinoma. Granulomatous reaction was noted in one case. Immunohistochemical study revealed that both tumors were immunoreactive with AE1/AE3, cytokeratin 7, and cytokeratin 19 but negative for carcinoembryonic antigen and cytokeratin 20. The stromal lymphocytes were composed of predominantly CD3(+) T cells. In situ hybridization for Epstein-Barr virus (EBV)-encoded RNA (EBER) showed positive nuclear signal in tumor cells but not in inflammatory cells in one case. The presence or absence of EBV genome was confirmed by polymerase chain reaction of LMP-1 gene in both cases. The LMP-1 gene also had a 30-bp deletion in Exon 3 as compared with the products from B95-8 cells. We further sequenced the PCR product and confirmed a 30-bp deletion between Nucleotide (nt) 168,282 and nt 168,253 corresponding to the B95-8 sequence. The clinical significance of 30-bp deletion in Exon 3 of the LMP-1 gene in lymphoepithelioma-like carcinoma of the liver warrants further investigation.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Enhancing 1 alpha-hydroxylase activity with the 25-hydroxyvitamin D-1 alpha-hydroxylase gene in cultured human keratinocytes and mouse skin.

1 alpha,25-Dihydroxyvitamin D(3) (1 alpha,25(OH(2))D(3)) and its analogs are used to treat psoriasis because of their potent antiproliferative activity. They have the potential for causing hypercalcemia, however, and patients often become resistant to the drug. We examined the feasibility of enhancing the cutaneous production of 1 alpha,25(OH(2))D(3) using a human 25-hydroxyvitamin D-1 alpha-hydroxylase (1 alpha-OHase) plasmid. The 1 alpha-OHase gene was fused to the green fluorescent protein gene (1 alpha-OHase-GFP) driven by the cytomegalovirus promoter. Transfection of cultured normal human keratinocytes with the 1 alpha-OHase-GFP plasmid resulted in a marked increase in the expression of 1 alpha-OHase-GFP in the mitochondria. Transfection of keratinocytes with 1 alpha-OHase-GFP or 1 alpha-OHase plasmids in vitro enhanced the 1 alpha-OHase activity substantially and increased the sensitivity of the keratinocytes to the antiproliferative effect of 25(OH)D(3). The 1 alpha-OHase-GFP plasmid was topically applied to shaved C57/BL6 mice. Twenty-four hours after topical application, immunohistochemical analysis of the skin for 1 alpha-OHase-GFP revealed the presence of 1 alpha-OHase-GFP in the epidermis and epidermal appendages including the hair follicles. The results from this study offer a unique new approach for the topical treatment of hyperproliferative disorders such as psoriasis and skin cancer using the 1 alpha-OHase gene that could locally increase the production of 1 alpha,25(OH(2))D(3) without causing hypercalcemia or resistance.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed2001

Treatment of vitamin D deficiency due to Crohn's disease with tanning bed ultraviolet B radiation.

In Crohn's disease, severe skeletal demineralization, secondary hyperparathyroidism, and muscle weakness can occur. This may be caused by impaired vitamin D absorption, resulting from extensive intestinal disease and resection of duodenum and jejunum, where vitamin D is absorbed. We report a 57-year-old woman with a long history of Crohn's disease and short-bowel syndrome who had only 2 feet of small intestine remaining after 3 bowel resections. She was taking a daily multivitamin containing 400 IU of vitamin D(3) and was dependent on total parenteral nutrition that contained 200 IU of vitamin D and calcium (18 mEq in a 1-L bag infused over 8 hours daily) for a period of 36 months. Despite the above replacement, she complained of bone pain and muscle weakness, and she continued to be vitamin D-deficient with a 25(OH)D level <20 ng/mL. She was then exposed to ultraviolet B (UVB) radiation in a tanning bed wearing a 1-piece bathing suit for 10 minutes, 3 times a week for 6 months at the General Clinical Research Center, Boston University Medical Center. She tolerated the irradiation well without evidence of erythema. After 4 weeks, her serum 25(OH)D level increased by 357% from 7 to 32 ng/mL, parathyroid hormone level decreased by 52% from 92 to 44 pg/mL, and the serum calcium level increased from 7.8 to 8.5 mg/dL. After 6 months of UVB treatment, her serum 25(OH)D level was maintained in the normal range and was free of muscle weakness, and bone and muscle pain.

Bone and Bones↗