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S H Yen

Publications and source records attributed to S H Yen.

At least 19 recordsLinked to original sources
PubMed2001

Enhanced neurofibrillary degeneration in transgenic mice expressing mutant tau and APP.

JNPL3 transgenic mice expressing a mutant tau protein, which develop neurofibrillary tangles and progressive motor disturbance, were crossed with Tg2576 transgenic mice expressing mutant beta-amyloid precursor protein (APP), thus modulating the APP-Abeta (beta-amyloid peptide) environment. The resulting double mutant (tau/APP) progeny and the Tg2576 parental strain developed Abeta deposits at the same age; however, relative to JNPL3 mice, the double mutants exhibited neurofibrillary tangle pathology that was substantially enhanced in the limbic system and olfactory cortex. These results indicate that either APP or Abeta influences the formation of neurofibrillary tangles. The interaction between Abeta and tau pathologies in these mice supports the hypothesis that a similar interaction occurs in Alzheimer's disease.

Alzheimer Disease↗
PubMed2001

Relationship of the extended tau haplotype to tau biochemistry and neuropathology in progressive supranuclear palsy.

Two extended haplotypes of the tau gene (H1 and H2) have been described. The frequency of H1 haplotype is increased in progressive supranuclear palsy (PSP). PSP is associated with filamentous tau lesions in neurons and glia, which are reportedly composed exclusively of tau isoforms with four repeats in the microtubule-binding domain (4R tau). To determine the influence of the tau haplotype on tau isoform composition and neuropathology, we studied 25 PSP cases and 6 Alzheimer's disease patients matched for age, sex, and postmortem delay. In the basal ganglia, tau and amyloid burdens were determined to see if there was an effect of concurrent Alzheimer-type pathology, and the ratio of 4R to 3R tau was measured in detergent-insoluble tau fractions. Insoluble tau from PSP was not composed exclusively of 4R tau. All brains had a mixture of 4R and 3R tau, but the ratio was different in Alzheimer's disease and PSP. In Alzheimer's disease there was less 4R than 3R tau, whereas the ratio was reversed in PSP. In PSP cases with concurrent Alzheimer-type pathology, the ratio of 4R to 3R was intermediate between Alzheimer's disease and PSP. The H1 haplotype had no effect on the 4R to 3R ratio or on tau and amyloid burdens. In summary, the H1 haplotype does not have a major influence on the pathological or biochemical phenotype of PSP.

Adult↗
PubMed2001

Efficacy of Re-188-labelled sulphur colloid on prolongation of survival time in melanoma-bearing animals.

UNLABELLED: In this study, the effectiveness of a 188Re labeled sulfur colloid with two particle size ranges was used to evaluate the effectiveness of this agent on melanoma tumors in mice in terms of animal lifespan. METHODS: Two separate group of animals were used for investigating biodistribution and survival time. A total of 188 B16F10-melanoma-bearing BDF(1) mice were injected intraperitoneally with 3.7 MBq (0.1mCi)/2mL of radiolabeled sulfur colloid ten days after intraperitoneal inoculation of 5x10(5) B16F10 melanoma cells/2ml. For group 1, 30 mice were sacrificed at 1, 4, 24, 48 and 72 hours for biodistribution studies. In group 2, 158 mice were divided into 9 groups (n=16 approximately 18/groups)each receiving respectively tumor alone, tumor with normal saline, cold colloid or hot colloid with 16, 23, 31, 46, 62, or 124 MBq activity. Each of these colloid groups was further divided into two groups, one receiving smaller particle sizes (<3 microm:80.4 +/-7.2%, colloid 1) and the other receiving larger particle sizes (<3 microm:12.3+/-1.0%, colloid 2). The animals were checked daily until death and their survival recorded. RESULTS: Colloid 2 showed higher accumulation in almost all tissues, the highest accumulation organ was tumor ( approximately 40%), then spleen ( approximately 20%), stomach ( approximately 15%), diaphragm ( approximately 3%), and liver ( approximately 2%). There was a significant increase in survival time with increasing amount of the larger-particle-size colloid. Administered levels of 16-31 MBq/mouse were most efficacious and with higher amounts the survival times decreased significantly below that of the controls. There was a significant difference in the dose-response curves for the two preparations. Protection factors (1/Relative-risk) of nearly 5 were achieved using the larger colloid size, and nearly 30 using the smaller colloid size. An amount of 16-31 MBq of the colloid 2 was the optimal activity in these studies. On the one hand, the survival data agreed well with the biodistribution data, where higher accumulation was found in tumor with colloid 2. CONCLUSION: Rhenium-188 offers on-site availability, medium half-life, higher beta-particle energy of 2.12 MeV for therapy and emission of 155keV gamma photon suitable for imaging. The present study demonstrated that 188Re-sulfur colloid is an effective agent in controlling tumor cells in the abdominal cavity in animals.

Animals↗
PubMed2001

Analysis of tauopathies with transgenic mice.

Intraneuronal filamentous inclusions composed of the microtubule-associated protein tau are a feature of several neurodegenerative diseases (including Alzheimer's disease) known as tauopathies. A pivotal finding was the identification in 1998 of mutations in tau associated with frontotemporal dementia with parkinsonism linked to chromosome 17. This demonstrated that tau dysfunction is sufficient to cause neurodegeneration, and indicated that tau is likely to play a crucial role in the pathogenesis of other tauopathies. However, the mechanism by which tau filamentous lesions form and their role in neurodegeneration remains uncertain. Recent progress in the development of transgenic mouse models of human tauopathy is allowing these questions to be addressed.

Animals↗
PubMed2001

Frontal lobe dementia with novel tauopathy: sporadic multiple system tauopathy with dementia.

We present a novel tauopathy in a patient with a 10-yr history of progressive frontal lobe dementia and a negative family history. Autopsy revealed mild atrophy of frontal and parietal lobes and severe atrophy of the temporal lobes. There were occasional filamentous tau-positive inclusions, but more interesting were numerous distinctive globular neuronal and glial tau-positive inclusions in both gray and white matter of the neocortex. Affected subcortical regions included substantia nigra, globus pallidus, subthalamic nucleus, and cerebellar dentate nucleus, in a distribution similar to progressive supranuclear palsy (PSP), but without significant accompanying neuronal loss or gliosis. Predominantly straight filaments were detected by electron microscopy (EM), while other inclusions were similar to fingerprint bodies. No twisted ribbons were detected. Immuno-EM studies revealed that only the filamentous inclusions were composed of tau. Immunoblotting of sarkosyl-insoluble tau revealed 2 major bands of 64 and 68 kDa. Blotting analysis after dephosphorylation revealed predominantly 4-repeat tau. Sequence analysis of tau revealed that there were no mutations in either exons 9-13 or the adjacent intronic sequences. The unique cortical tau pathology in this case of sporadic multiple system tauopathy with dementia adds a new pathologic profile to the spectrum of tauopathies.

Aged↗
PubMed2001

Phase II trial of systemic recombinant interleukin-2 in the treatment of refractory nasopharyngeal carcinoma.

BACKGROUND: Interleukin-2 (IL-2) is a cytokine produced by activated T cells, which has shown powerful immunostimulatory and antineoplastic properties. Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus-associated cancer with abundant lymphocyte infiltration histologically. The activity of IL-2 in the treatment of NPC patients is currently unknown. A phase II study was, therefore, initiated to evaluate the efficacy, toxicity and immunological consequences of intravenous bolus IL-2 in patients with recurrent/metastatic NPC. METHODS: Between November 1996 and April 1997, 14 patients with recurrent/metastatic NPC were entered into the study. Recombinant IL-2 (Proleukin, Chiron) was injected by intravenous bolus every 8 h at 72,000 IU/kg for a maximum of 15 doses. After 7 days, patients were retreated with a second identical cycle of therapy. Those patients who were stable or responding to treatment 5-6 weeks later went on to receive another course (two cycles) of therapy. All patients received prophylactic antibiotics and antipyretic medicine. Response and toxicities were evaluated. Serial plasma level of TNF-alpha, IL-6, soluble IL-2 receptor, IL-10 and soluble CD8 were determined. RESULTS: Fourteen patients received a total of 34 cycles of therapy. No response was observed. Fifty percent had stable disease, 50% had progressive disease after a median of two cycles of therapy. There was one treatment-related death from acute myocardial infarction. Body weight increase (>5%) occurred in 80% of cycles, and hypotension (BP <80 mm Hg systolic) occurred in 53%. Serum creatinine increase (>2 mg%) occurred in 24% of cycles, and SGOT/SGPT increase (>3x) in 10% of cycles. Symptoms of somnolence, general malaise, nausea and vomiting, pruritus, xerostomia, desquamation were generally mild to moderate but rapidly reversible. CONCLUSION: The single modality of intravenous bolus IL-2 at the dose level of 72,000 IU/kg is clinically ineffective in NPC patients. Potential mechanisms of the ineffectiveness of IL-2 therapy on NPC patients are discussed.

Adult↗
PubMed2001

Preclinical evaluation of locoregional delivery of radiolabeled iododeoxyuridine and thymidylate synthase inhibitor in a hepatoma model.

UNLABELLED: We report improved incorporation of the radiolabeled-thymidine analog [125I/131I]5-iodo-2'-deoxyuridine ([125I/131I]IdUrd) into DNA by the addition of Thymitaq, a thymidylate synthase inhibitor, as a strategy of molecular radiotherapy for hepatoma treatment. METHODS: The synergistic effect of combination [125I]IdUrd and Thymitaq in clonogenic survival and DNA incorporation was shown on the human hepatoma cell line Hep3B. Radiobiodistribution of intrahepatic arterially injected [125I]IdUrd and Thymitaq was studied in a rat N1S1 hepatoma model. In vivo therapeutic effects of locoregional delivery of both drugs were evaluated in mouse subcutaneous hepatoma and ascitic hepatoma models. RESULTS: In a clonogenic assay, Thymitaq showed a synergistic effect with [125I]IdUrd but not cold IdUrd. Thymitaq had a dose-dependent modulation effect on DNA-[125I]IdUrd incorporation. The biodistribution study indicated a slower clearance rate of [125I]IdUdR in the hepatoma as well as an initially higher uptake of [125I]IdUrd into DNA when the [125I]IdUrd was combined with Thymitaq. In vivo studies showed a superior therapeutic effect of combination Thymitaq and [125I]IdUrd in both subcutaneous and ascites tumor models, but the combination of [131I]IdUrd and [125I]IdUrd may be more effective than Auger electron emitters alone for the treatment of subcutaneous tumor. CONCLUSION: The strategy of locoregional delivery of [125I/131I]IdUrd to a tumor site through an intrahepatic arterial, intratumoral, or intraperitoneal route in combination with Thymitaq is promising and may also have a favorable therapeutic index in vivo.

Animals↗
PubMed2000

Missense tau mutations identified in FTDP-17 have a small effect on tau-microtubule interactions.

Frontotemporal dementia with Parkinsonism linked to chromosome 17 (FTDP-17) is a group of related disorders frequently characterized by the formation of tau inclusions in neurons and glial cells. To determine whether the formation of tau inclusions in FTDP-17 results from an alteration in the ability of mutant tau to maintain the microtubule (MT) system, we compared wild type four-repeat tau with three FTDP-17 mutants (P301L, V337M and R406W) for their ability to bind MT, promote MT assembly and bundling. According to in vitro binding and assembly assays, P301L is the only mutant that demonstrates a small, yet significant reduction, in its affinity for MT while both P301L and R406W have a small reduction in their ability to promote tubulin assembly. Based on studies of neuroblastoma and CHO cells transfected with GFP-tagged tau DNA constructs, both mutant and wild type tau transfectants were indistinguishable in the distribution pattern of tau in terms of co-localization with MT and generation of MT bundles. These results suggest that missense mutation of tau gene do not have an immediate impact on the integrity of MT system, and that exposure of affected neurons to additional insults or factors (e.g., aging) may be needed to initiate the formation of tau inclusions in FTDP-17.

Animals↗
PubMed2000

Distinctive neuropathology revealed by alpha-synuclein antibodies in hereditary parkinsonism and dementia linked to chromosome 4p.

The identification of the alpha-synuclein gene on chromosome 4q as a locus for familial Lewy-body parkinsonism and of alpha-synuclein as a component of Lewy bodies has heralded a new era in the study of Parkinson's disease. We have identified a large family with Lewy body parkinsonism linked to a novel locus on chromosome 4p15 that does not have a mutation in the alpha-synuclein gene. Here we report the clinical and neuropathological findings in an individual from this family and describe unusual high molecular weight alpha-synuclein-immunoreactive proteins in brain homogenates from brain regions with the most marked neuropathology. Distinctive histopathology was revealed with alpha-synuclein immunostaining, including pleomorphic Lewy bodies, synuclein-positive glial inclusions and widespread, severe neuritic dystrophy. We also discuss the relationship of this familial disorder to a Lewy body disease clinical spectrum, ranging from Parkinson's disease to dementia with psychosis.

Brain↗
PubMed2000

A double-labeling immunohistochemical study of tau exon 10 in Alzheimer's disease, progressive supranuclear palsy and Pick's disease.

Neurofibrillary tangles (NFT), one of the histopathological hallmarks of Alzheimer's disease (AD) and progressive supranuclear palsy (PSP), and Pick bodies in Pick's disease (PiD) are composed of microtubule-associated protein tau, which is the product of alternative splicing of a gene on chromosome 17. Alternative expression of exon 10 leads to formation of three- or four-repeat tau isoforms. To study the differential expression of exon 10, we performed double-labeling immunohistochemistry of the hippocampal formation in nine AD, four PSP and three PiD cases. Cryostat sections were processed with and without formic acid (FA) treatment, and double-stained with anti-tau (Alz-50 or PHF-1) or anti-amyloid P component antibodies and one of two specific anti-exon 10 antibodies (E-10). The effect of proteinase-K treatment was also evaluated. The results suggest the following. First, in AD, E-10 immunoreactivity is present in most intracellular NFT, but not in most dystrophic neurites and neuropil threads, suggesting differential expression of tau isoforms in specific cellular domains. Second, in AD, E-10 immunoreactivity is lost or blocked in most extracellular NFT, possibly due to proteolysis. Third, in PSP, E-10 immunoreactivity is hidden or blocked in NFT and tau-positive glial inclusions, but FA treatment exposes the epitope consistent with the hypothesis that PSP inclusions contain four-repeat tau. Fourth, E-10 immunoreactivity is present in dentate fascia NFT in AD and PSP, but not in Pick bodies in the dentate fascia or other areas. The results suggest that expression of exon 10 in tau is specific for cellular domains in a disease-specific manner.

Aged↗
PubMed2000

Dopamine and 7-OH-DPAT may act on D(3) receptors to inhibit tuberoinfundibular dopaminergic neurons.

Whether the tuberoinfundibular dopaminergic (TIDA) neurons resided in the dorsomedial arcuate nucleus (dmARN) can respond to dopamine and a dopamine D(3) receptor agonist, 7-hydroxydipropylaminotetralin (7-OH-DPAT), was the focus of this study. In studies using extracellular single-unit recording of dmARN neurons in brain slices obtained from ovariectomized rats, dopamine and 7-OH-DPAT inhibited 60.1% (n = 141) and 80.9% (n = 47) of recorded dmARN neurons, respectively. Other dopamine D(1) or D(2) receptor agonists were not as effective. Intracerebroventricular injection of 7-OH-DPAT (10(-9) mol/3 microl) in ovariectomized, estrogen-primed rats significantly lowered the TIDA neuronal activity as determined by 3, 4-dihydroxyphenylacetic acid (DOPAC) levels in the median eminence. Co-administration of a putative D(3) receptor antagonist, U-99194A, could prevent the effect of 7-OH-DPAT. Unilateral microinjection of 7-OH-DPAT or dopamine itself (10(-11)-10(-9) mol/0.2 microl) into the right dmARN exhibited the same inhibitory effect on TIDA neurons. In all, dopamine may act on D(3) receptors to exhibit an inhibitory effect on its own release from the TIDA neurons.

Animals↗
PubMed2000

Neurofibrillary tangles, amyotrophy and progressive motor disturbance in mice expressing mutant (P301L) tau protein.

Neurofibrillary tangles (NFT) composed of the microtubule-associated protein tau are prominent in Alzheimer disease (AD), Pick disease, progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). Mutations in the gene (Mtapt) encoding tau protein cause frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), thereby proving that tau dysfunction can directly result in neurodegeneration. Expression of human tau containing the most common FTDP-17 mutation (P301L) results in motor and behavioural deficits in transgenic mice, with age- and gene-dose-dependent development of NFT. This phenotype occurred as early as 6.5 months in hemizygous and 4.5 months in homozygous animals. NFT and Pick-body-like neuronal lesions occurred in the amygdala, septal nuclei, pre-optic nuclei, hypothalamus, midbrain, pons, medulla, deep cerebellar nuclei and spinal cord, with tau-immunoreactive pre-tangles in the cortex, hippocampus and basal ganglia. Areas with the most NFT had reactive gliosis. Spinal cord had axonal spheroids, anterior horn cell loss and axonal degeneration in anterior spinal roots. We also saw peripheral neuropathy and skeletal muscle with neurogenic atrophy. Brain and spinal cord contained insoluble tau that co-migrated with insoluble tau from AD and FTDP-17 brains. The phenotype of mice expressing P301L mutant tau mimics features of human tauopathies and provides a model for investigating the pathogenesis of diseases with NFT.

Amino Acid Substitution↗
PubMed2000

Life-threatening haemorrhage from a sternal metastatic hepatocellular carcinoma.

Rupture of the tumour is a catastrophic complication of hepatocellular carcinoma. The prognosis in patients with a ruptured hepatocellular carcinoma is usually unfavourable. We describe a 46-year-old man who suffered from visible massive tumour haemorrhage due to a hepatitis B-related hepatocellular carcinoma that metastasized to the sternal bone. The prominent tumour mass was bulging over the anterior chest wall on the sternum of the patient, and bled spontaneously. This episode of life-threatening haemorrhage was stopped by surgical ligation of the bleeding site. Palliative radiotherapy shrank the tumour mass size and prevented further possible bleeding. This is likely to be the first reported case with a visible spontaneous tumour bleeding from a sternal metastatic hepatocellular carcinoma.

Bone Neoplasms↗
PubMed2000

Sensitization of neuronal cells to oxidative stress with mutated human alpha-synuclein.

Linkage of alpha-synuclein (alpha-SN) mutations to familial Parkinson's disease (PD) and presence of alpha-SN as a major constituent of Lewy body in both sporadic and familial PD implicate alpha-SN abnormality in PD pathogenesis. Here we demonstrate that overexpression of wild-type or mutant alpha-SN does not cause any deleterious effect on the growth or continued propagation of transfected human cells, but overproduction of mutant alpha-SN heightens their sensitivity to menadione-induced oxidative injury. Such enhanced vulnerability is more pronounced in neuronal transfectants than in their nonneuronal counterparts and is associated with increased production of reactive oxygen species. The data suggest that mutated alpha-SN, especially with an alanine-to-proline substitution at residue 30, sensitizes neuronal cells to oxidative damage.

Cell Line↗
PubMed2000

Successful initial treatment with weekly etoposide, epirubicin, cisplatin, 5-fluorouracil and leucovorin chemotherapy in advanced gastric cancer patients with disseminated intravascular coagulation.

BACKGROUND: Acute disseminated intravascular coagulation (DIC) is a rare but severe complication of gastric adenocarcinoma. Conventional treatments, such as fresh frozen plasma, platelet replacement and heparin injections, are disappointing. The only way to correct this fatal condition is to control the underlying cancer promptly by effective chemotherapy. Here the successful initial control of acute DIC in gastric cancer patients with weekly EEPFL chemotherapy is reported. METHODS: Advanced gastric cancer patients complicated with acute DIC were eligible. Patients were treated with weekly EEPFL therapy (etoposide 40, epirubicin 10, cisplatin 25, 5-fluorouracil 2200 and leucovorin 120 mg/m2 ). Response, survival and toxicity were evaluated. RESULTS: From April 1997 to April 1999, six patients were included in this study. All patients received EEPFL chemotherapy. Clinical and laboratory evidence of acute DIC stabilized quickly after starting chemotherapy. Four patients showed a partial response, one stable disease and one progressive disease. The toxicity was mild and well tolerated. Median survival was 28 weeks (12, 14, 26, 30, 30 and 32 weeks). All patients suffered from a relapse of DIC after initial successful control and died within 30 days of clinical and laboratory evidence of acute DIC relapse. CONCLUSION: EEPFL therapy is an effective chemotherapy regimen for patients with advanced gastric cancer associated with acute DIC. The prognosis is poor if the DIC relapses after the initial successful control.

Acute Disease↗
PubMed2000

Salvage surgery for recurrent nasopharyngeal carcinoma.

OBJECTIVE: To evaluate the efficacy of salvage surgery in the treatment of recurrent nasopharyngeal carcinoma (NPC) at the primary site. STUDY DESIGN: A retrospective investigation of the outcome of salvage surgery for 28 patients with recurrent NPC after definite radiation therapy. METHODS: The nasopharynx was approached anteroposteriorly by the transmaxillary approach (maxillary swing, maxillectomy) or inferior approach (midline mandibulotomy or median labiomandibular glossotomy), or laterally by modified facial translocation or transpterygoid approach; intentional ligation of the internal carotid artery was performed after establishment of extracranial-intracranial (EC-IC) bypass in one patient; postoperative irradiation was given to the patients with positive pathological margins. RESULTS: Nine patients lived without disease for 20 to 93 months (mean interval, 52 mo) after surgery; among them, eight patients had T1 tumors that were resected totally by surgery via anteroposterior approaches and the other patient had postoperative irradiation to control the disease. Seven patients had local recurrence 8 to 21 months after treatment. Four patients developed distant metastases, including one patient with a T2b tumor that was totally resected through modified facial translocation approach with ligation of internal carotid artery. Eight patients died of other causes; internal carotid artery blowout was the cause of death in four of these eight patients. CONCLUSIONS: In most cases of recurrence, T1 nasopharyngeal tumors can be resected totally by anteroposterior approaches; for T2 or larger tumors, postoperative irradiation is usually necessary. Otherwise, facial translocation offers a better chance to completely resect the tumors. Internal carotid artery is better ligated if patients have received greater than 70 Gy irradiation or if the artery must be exposed during the surgery. We suggest that EC-IC bypass be used to avoid the possible complications (or cerebral ischemic stroke) caused by ligation of internal carotid artery. The transmaxillary approach is favored in the management of nasopharyngeal tumor recurrence with nasal cavity extension, and midline mandibulotomy is more suitable for resection of posterior margin of nasopharyngeal tumor recurrence. Facial translocation offers the widest operative field and is the most versatile approach for radical resection of nasopharyngeal tumor recurrence, but the surgeon should be skilled in the management of the facial nerves to reduce morbidity.

Adult↗
PubMed2000

Prognostic role of pericardial fluid cytology in cardiac tamponade associated with non-small cell lung cancer.

BACKGROUND AND STUDY OBJECTIVES: Cardiac tamponade is a life-threatening complication of non-small cell lung cancer (NSCLC). Malignant pericardial effusion signifies advanced disease, but the significance of a negative pericardial fluid cytology in patients with advanced lung cancer is still controversial. The differential diagnosis of cytology-negative pericardial effusion is difficult and sometimes impossible. The purpose of this study is to determine the prognostic role of pericardial fluid cytology in patients with NSCLC and cardiac tamponade. DESIGN: Retrospective review of patients with concurrent NSCLC and cardiac tamponade over a 10-year period. METHODS AND RESULTS: Eighty-two patients were included in this study. Pericardial fluid cytology was positive in 60 patients and negative in 22 patients. The overall median survival was 74.5 days, and 1-year survival was 7.3%, with no survival difference between the two groups (p = 0.2506). However, there was a significant survival difference after different treatment strategies. Patients receiving systemic chemotherapy survived longer than those receiving local therapy (p<0.001), and these patients, in turn, survived longer than those receiving supportive treatment (p<0.001). CONCLUSIONS: When patients have concurrent advanced NSCLC and cardiac tamponade, the most likely cause of the pericardial effusion is the cancer itself, regardless of the results of the cytologic examination. Our results suggest that systemic chemotherapy might prolong survival in such patients, but further prospective, randomized study is necessary.

Aged↗