Biomedical subjects

C Y Chang

Publications and source records attributed to C Y Chang.

At least 91 records · Page 5Linked to original sources

PubMed2000

Lipopolysaccharide-stimulated nitric oxide production and inhibition of cell proliferation is antagonized by ethanol in a clonal macrophage cell line.

Both chronic and acute ethanol exposure have been shown to be cytotoxic and also to disrupt normal cell function or responses in a variety of cell types. Macrophage function has specifically been shown to be disrupted by chronic ethanol exposure by mechanisms that have not been elucidated. It is known that exposure of macrophages to lipopolysaccharide (LPS) from gram-negative bacteria will decrease the number of cells. Since increased exposure to endotoxin is often associated with chronic alcoholism, this may be one mechanism to account for loss of macrophages in alcoholic patients. The loss of macrophages, as a consequence of endotoxin treatment, appears to be linked to cell activation and, in particular, LPS-stimulated synthesis of nitric oxide which has been suggested to cause an increase in apoptosis. Ethanol also increases apoptosis in some cell types but, in general, ethanol inhibits activation of macrophages. Thus, the overall effect on cell numbers and cell proliferation elicited by treating macrophages concomitantly with ethanol and LPS depends on the balance between inhibiting LPS-mediated activation and the actions of ethanol. The interaction between ethanol and LPS was investigated in a macrophage cell line (RAW 264.7 cells) by measuring nitric oxide production and cell proliferation. A 24-h exposure to ethanol (100 mM) decreased [3H]-thymidine incorporation significantly. LPS treatment elicited a concentration-dependent decrease in [3H]-thymidine incorporation at LPS concentrations of 0.1 ng/ml to 1000 ng/ml and stimulated nitric oxide production at concentrations above 1 ng/ml. LPS-stimulated nitric oxide production was inhibited by ethanol (20 to 100 mM) and the nitric oxide synthesis inhibitor, N(G)Nitro-L-arginine methyl L-NAME) ester (100 and 500 microM). However, LPS-inhibited [3H]-thymidine incorporation was not be totally reversed by ethanol- or L-NAME-treatment. A direct correlation between nitric oxide production and inhibition of cell proliferation could not be demonstrated. However, it appears that ethanol and LPS do affect some common mechanism(s) in this cell line.

Animals↗

PubMed2000

Migration of intradural epidermoid matrix: embryologic implications.

The migratory behavior of acquired cholesteatoma matrices (those arising from the tympanic membrane) has been described previously. This tissue is derived embryologically from the first branchial groove and represents the only migratory epithelium arising from the branchial groove system. If the matrix from a cerebellopontine angle (CPA) epidermoid tumor exhibits migratory behavior similar to that of acquired cholesteatomas, a first branchial groove site of origin for CPA epidermoids would be supported. Intradural CPA epidermoid cells were grown in alpha-minimum essential medium. The cultures were examined daily, and cell mass migration rates were measured. It was observed that intradural epidermoid tumor matrix harvested from the CPA exhibited migration in vitro. Its migratory properties were indistinguishable from those of acquired cholesteatomas, which are embryologically derived from the first branchial groove. These data support the theory that purely intradural epidermoids are derived from cells of the first branchial groove.

Adult↗

PubMed2000

Two new gene cassettes, dfr17 (for trimethoprim resistance) and aadA4 (for spectinomycin/streptomycin resistance), inserted in an Escherichia coli class 1 integron.

Two new gene cassettes, dfr17 and aadA4, inserted in a class 1 integron of Escherichia coli EC107, are described here. The dfr17 cassette encodes trimethoprim resistance and has 91% identity with the dfrVII dihydrofolate reductase gene. The aadA4 cassette confers resistance to spectinomycin and streptomycin and shows 94% identity with the aadA3 gene. The integron carrying the dfr17 and aadA4 cassettes was located on a conjugative plasmid, pEC1072.

DNA Transposable Elements↗

PubMed2000

Crystallization and preliminary X-ray analysis of CTLA-4 (CD152) membrane-external domain.

CTLA-4 (CD152) is involved in T-lymphocyte co-stimulatory pathways modulating both humoral and cellular immune response. The membrane-external domain has been prepared and crystallized. The unit-cell parameters are a = b = 43, c = 143 A with the symmetry of space group P3(1)21 or its enantiomer and the crystals diffract to 2. 7 A resolution at synchrotron beamlines.

Abatacept↗

PubMed2000

The oxidative metabolism of circulating phagocytes in ankylosing spondylitis: determination by whole blood chemiluminescence.

OBJECTIVE: Superoxide anion radicals within the human body are regarded as a major cause of inflammation. However, their role in the pathogenesis of ankylosing spondylitis (AS) has not been well identified. This study aimed at investigating the relation between AS and the oxidative metabolism of phagocytes in whole blood. METHODS: 24 patients with classic AS were examined to determine their clinical status; complete blood count, erythrocyte sedimentation rate (ESR), and C reactive protein (CRP) were determined, and levels of the superoxide anion radicals in the patients with AS and 21 healthy subjects were assessed by the ultraweak chemiluminescence method. Subsequently, the relation between this disease and phagocytes was examined by using N-formyl-methionyl-leucyl-phenylalanine (fMLP) and phorbol-12-myristate-13-acetate (PMA) stimulants. RESULTS: In clinical assessments, patients with AS had abnormally raised serum CRP (>10 mg/l) and ESR (>15 mm/1st h) levels. In contrast with healthy subjects, patients with AS had significantly increased rates of superoxide anion radical production in their whole blood either in the resting state or with either fMLP or PMA stimulation. In addition, chemiluminescence maximum light intensity was significantly higher in patients with AS than in healthy subjects after fMLP or PMA stimulation. CONCLUSIONS: Our results suggest that the phagocytes of patients with AS are partly activated in the resting state, and are sensitive to fMLP or PMA stimulation. The priming of phagocytes in the bloodstream is likely to be a causative factor in the onset of AS.

Adult↗

PubMed2000

Development of peptide antagonists that target estrogen receptor beta-coactivator interactions.

The biological actions of estrogen are manifest through two genetically distinct estrogen receptors (ER alpha and ER beta) that display nonidentical expression patterns in target tissues. The phenotypic alterations in response to estrogens in mice disrupted for either or both of these receptors are not identical, suggesting that each subtype plays a unique role in ER-action. However, the lack of subtype-specific agonists and antagonists has made it difficult to define the processes that are regulated by ER alpha and/or ER beta. Previously, we have reported the identification and characterization of a series of LXXLL-containing peptide antagonists that block estrogen signaling by preventing the association of ER alpha with required coactivators. As expected, given the similarity of the coactivator binding pockets among nuclear receptors, most of the peptide antagonists identified inhibited the activity of multiple receptors. However, by altering sequences flanking the core LXXLL motif, some receptor selectivity was afforded. Building on this observation, we have screened combinatorial phage libraries, expressing peptides in the format X7LXXLLX7, for peptides that interact in a specific manner with ER beta. Using this approach, a series of highly specific, potent peptide antagonists have been identified that efficiently inhibit ER beta-mediated estrogen signaling when introduced into target cells. Interestingly, in cells where both ER subtypes were expressed, these ER beta antagonists were capable of attenuating ER action, suggesting that ER alpha and ER beta do indeed form functional heterodimeric complexes. We believe that suitably formulated versions of these peptides can be used to study ER beta action in vitro and in vivo. In addition, the unanticipated specificity of the peptides identified should serve as an impetus to investigate the use of this approach to develop peptide antagonists of other nuclear receptors and unrelated transcription factors.

Amino Acid Motifs↗

PubMed2000

Temporally distinct and ligand-specific recruitment of nuclear receptor-interacting peptides and cofactors to subnuclear domains containing the estrogen receptor.

Ligand binding to estrogen receptor (ER) is presumed to regulate the type and timing of ER interactions with different cofactors. Using fluorescence microscopy in living cells, we characterized the recruitment of five different green fluorescent protein (GFP)-labeled ER-interacting peptides to the distinct subnuclear compartment occupied by blue fluorescent protein (BFP)-labeled ER alpha. Different ligands promoted the recruitment of different peptides. One peptide was recruited in response to estradiol (E2), tamoxifen, raloxifene, or ICI 182,780 incubation whereas other peptides were recruited specifically by E2 or tamoxifen. Peptides containing different sequences surrounding the ER-interacting motif LXXLL were recruited with different time courses after E2 addition. Complex temporal kinetics also were observed for recruitment of the full-length, ER cofactor glucocorticoid receptor-interacting protein 1 (GRIP1); rapid, E2-dependent recruitment of GRIP1 was blocked by mutation of the GRIP1 LXXLL motifs to LXXAA whereas slower E2 recruitment persisted for the GRIP1 LXXAA mutant. This suggested the presence of multiple, temporally distinct GRIP 1 recruitment mechanisms. E2 recruitment of GRIP1 and LXXLL peptides was blocked by coincubation with excess ICI 182,780. In contrast, preformed E2/ER/GRIP1 and E2/ER/LXXLL complexes were resistant to subsequent ICI 182,780 addition whereas ICI 182,780 dispersed preformed complexes containing the GRIP1 LXXAA mutant. This suggested that E2-induced LXXLL binding altered subsequent ligand/ER interactions. Thus, alternative, ligand-selective recruitment and dissociation mechanisms with distinct temporal sequences are available for ER alpha action in vivo.

Active Transport, Cell Nucleus↗

PubMed2000

Synthesis and anti-platelet, anti-inflammatory and anti-allergic activities of methoxyisoflavanquinone and related compounds.

In a continuation of our search for novel anti-platelet agents, isoflavone quinone and isoflavanquinone were selected as lead compounds and the synthesis of their methoxy derivatives was carried out. Among them, the 4'- and 7-methoxy derivatives were successfully prepared, whereas the attempt to obtain 3'-methoxy derivatives resulted in their isomers, 3'-methoxyflavone quinone and 3'-methoxyflavanquinone, instead. After screening for their anti-platelet, anti-inflammatory and anti-allergic activities, a preliminary structure-activity relationship was established. Compounds 6c, 7a-c, 8c and 9a-c were found to exhibit significant activities. In particular, compound 7c demonstrated very potent anti-platelet, anti-inflammatory and anti-allergic activities and was then recommended for further pharmacological investigation.

Animals↗

PubMed2000

An unusual case of organophosphate intoxication of a worker in a plastic bottle recycling plant: an important reminder.

A young man was sent to our emergency unit because he had suffered from vomiting and cold sweating for 2 days. At the time he was admitted, he had no acute abdominal pains or gastrointestinal symptoms, and a physical examination revealed nothing but a faster heart rate and moist, flushing skin. The patient had worked for 6 years at a plastic bottle-recycling factory, but none of his co-workers had the same symptoms. Nevertheless, because the plant also recycled pesticide bottles, we suspected organophosphate pesticide intoxication. The patient's plasma acetylcholinesterase level was checked, revealing 1498.6 microU/L (normal range: 2,000-5, 000) on the first day and 1,379 microU/L on the second day. Upon questioning, the patient recalled that one of his shoe soles had been damaged and that his foot had been wet from walking all day in rain collected on the factory floor on the day that his symptoms first occurred. We conducted a study in the change of preshift and postshift acetylcholinesterase levels among six of his co-workers on a rainy day. We used the Wilcoxon signed rank test to compare the preshift and postshift plasma acetylcholinesterase levels; no significant difference was revealed (p = 0.600), leaving contamination via the damaged shoe sole suspect. We reviewed the literature on organophosphate intoxication; pesticide bottle-recycling factories were reported to be at a low risk of organophosphate toxicity in the working environment. However, because the potential risk of intoxication is still present, protective equipment such as clothing, gloves, and water-proof shoes should be worn, and employees should be educated on the potential risks.

Acetylcholinesterase↗

PubMed2000

Evaluation of the regenerative effect of a 25% doxycycline-loaded biodegradable membrane for guided tissue regeneration.

BACKGROUND: Biodegradable materials have been successfully utilized for guided tissue regeneration (GTR) and local delivery systems (LDS) because they are biocompatible, less cytotoxic, and do not require removal. Several studies have demonstrated that tetracyclines (TCs), when applied topically, stimulated osteogenesis in experimental bone defects. The purpose of this study was to evaluate the regenerative effect of a 25% doxycycline-loaded biodegradable GTR membrane (Doxy-M) in dogs. METHODS: Doxy-M was made by coating the inner surface of a biodegradable membrane (BD-M) with 25% doxycycline. Five male mongrel dogs with 20 created osseous defects were enrolled. The plain BD-M was used as the control membrane. Either Doxy-M or BD-M was applied in 20 randomly selected defects (10 Doxy-M, 10 BD-M) for 12 weeks with the GTR technique. The histometric analysis was evaluated with the following parameters: defect height (DH), apical extension of junctional epithelium (AEJP), new cementum height (NCH), new bone height (NBH), and new bone area (NBA). RESULTS: The Doxy-M-treated defects showed more pronounced new bone formation and less crestal bone resorption than the BD-M-treated defects. There were no statistically significant differences between the two groups in DH, AEJP, and NCH. Statistically significantly larger NBH (P <0.05) and NBA (P<0.005) were seen in the Doxy-M-treated defects. CONCLUSIONS: The results strongly suggest that Doxy-M may have a beneficial effect on osteogenesis to favor periodontal regeneration.

Absorbable Implants↗

PubMed2000

Imaging of invasiveness of pituitary adenomas.

The purpose of our study was to examine the tumor size, imaging invasiveness of the pituitary macroadenomas (PMA) and to evaluate the directions of PMA spread. One hundred and thirty-five patients with PMA were examined with MRI and/or CT for pre-operative evaluation. We retrospectively reviewed the CT and MRI to identify tumor size, extension and to evaluate the directions of tumor spread. One hundred and seventeen patients (87%) had suprasellar extension with compression of optic apparatuses, twelve patients (9%) had extension of tumor upward to hypothalamus and third ventricle. Infrasellar extension via the floor of the sella and sphenoid sinus was found in thirty-eight patients (28%), and further downward extension to ethmoid sinus, nasopharynx and/or skull base was depicted in five patients (4%). Twenty-two patients (16%) had lateral invasion to the cavernous sinus and associated cranial nerves. Temporal and frontal extensions were depicted in seven patients (5%) and six patients (4%), respectively. Five patients (4%) had posterior subtentorial extension to posterior fossa. Histologically, only two patients showed microscopic invasive features. There was no correlation between histologic features and imaging invasiveness. The PMA had the potential of multi-directional extension. This experience indicated any type of pituitary adenoma could invade surrounding structures. Suprasellar invasion was the most common direction of pituitary adenoma spread, followed by infrasellar, lateral, anterior and posterior routes.

Adenoma↗

PubMed2000

Endovascular embolization of intractable epistaxis.

BACKGROUND: We undertook this study to define the role of angiography and endovascular embolization in the treatment of patients with intractable epistaxis. METHODS: A series of 19 patients with massive intractable epistaxis, all treated with endovascular embolization were reviewed. There were 15 males and four females ranging in age from 18 to 70 years, with a mean age of 38 years. The predisposing factors of intractable epistaxis were head and neck tumors (n = 11), idiopathic symptoms (n = 3), surgical complications (n = 2), arteriovenous malformation of the face (n = 1), thrombocytopenia (n = 1) and trauma (n = 1). Polyvinyl alcohol (PVA) particles and gelfoam plugs were used as embolic agents in 11 patients for devascularization; detachable balloons with N-butyl-2-cyanoacrylate (NBCA) were used in four patients for vascular occlusion; NBCA and/or coils were used in four patients in the carotid and subclavian arteries for obliteration of pseudoaneurysms. RESULTS: Complete cessation of epistaxis was achieved in all 19 patients immediately after embolization. Seven patients had also undergone surgical tumor removal at two to five days after embolization. Two patients experienced mild to moderate facial pain on the first day after the procedure, but the symptoms later subsided. No significant complication or recurrence was observed in 18 patients. One patient with advanced hypopharyngeal carcinoma died two weeks after embolization due to another episode of massive epistaxis. Clinical follow-up for these patients was 15 days to eight years, with a mean of 41 months. CONCLUSIONS: Therapeutic endovascular embolization of intractable epistaxis is both efficient and safe. It should be considered as the primary treatment modality in intractable epistaxis.

Adolescent↗

PubMed2000

High resolution MRI of adrenal glands in patients with primary aldosteronism.

BACKGROUND: We studied the role of high-resolution magnetic resonance imaging (MRI) of the adrenal glands using a surface coil in patients with primary aldosteronism to differentiate aldosterone-producing adenomas (APA) from idiopathic hyperplasia of the adrenal gland (IHA). The data obtained were used to decide on surgical or nonsurgical treatment for patients. METHODS: High-resolution MRI with SE T1WI, FSE T2WI and paired in- and out-phase images of the adrenal glands of 41 patients with clinically documented primary aldosteronism were collected. The images were reviewed in comparison with other differentiating tests. RESULTS: Nineteen of the 41 patients were diagnosed with APA on MRI. Surgical and pathologic proof of APA was obtained in 10 cases and solitary macronodular hyperplasia was found in one case. Among these 11 cases, there were no false positive findings on MRI, while correct detectability of high-resolution computerized tomography (CT) was 62.5% (5/8); for adrenal venous sampling, it was 37.5% (3/8); and for NP-59 adrenal scanning, it was 42.9% (3/7). In eight cases with biochemically favored APA and no surgical proof, MRI and CT showed the same lesion detection rate, while there was no concordance with venous sampling, and concordance of only 33.3% (2/6) for adrenal scanning. In the remaining 22 patients without focal lesions on MRI, there was poor concordance among the four test modalities, with frequently conflicting results. CONCLUSIONS: In patients with definitive results of noninvasive biochemical tests for APA, and positive findings of unilateral, focal adrenal lesion on MRI or CT, unilateral adrenalectomy may be justified without further tedious and invasive examinations. CT should still be the first screening test; however, high-resolution MRI is a useful diagnostic supplement for patients with strong clinical evidence of APA and negative or equivocal findings on CT.

Adrenal Glands↗

PubMed2000

Cavernous sinus gas.

Gas within the cavernous sinus is an unusual finding. We report three patients who demonstrated gas in the cavernous sinus on computerized tomography (CT). The clinical information of these patients was reviewed for the possible source of the gas and the symptoms induced by the gas. Cavernous sinus gas was seen in two patients with sphenoid sinus fracture and in one patient after intravenous fluid infusion. None of the patients had symptoms referable to the cavernous sinus gas, but one patient had a grave prognosis due to trauma. Identification of cavernous sinus gas on CT and correlation with the clinical information is mandatory for further management.

Adult↗

PubMed2000

Cervical carcinoma: assessment of parametrial invasion and lymph node metastasis with magnetic resonance imaging.

BACKGROUND: Clinical tumor staging of cervical carcinoma has its limitations. The purpose of this study was to stage cervical carcinoma by magnetic resonance imaging (MRI), with an emphasis on the assessment of parametrial invasion and pelvic lymph node metastasis. METHODS: MRI was performed in 51 women with tissue-proven cervical carcinoma 2 weeks prior to surgery. Images were analyzed for parametrial invasion, pelvic lymph node metastasis and tumor stage. The results were compared with the histopathologic findings after surgery in all patients. RESULTS: In assessing parametrial invasion, MRI had an accuracy of 94%. In assessing pelvic lymph node metastases, MRI was accurate in 86.3% of cases. In determining stage of disease, MRI had an accuracy of 76.5%. The accuracy of MRI in differentiating localized (< or = stage IIA) from advanced disease (> or = stage IIB) was 94.1%. CONCLUSIONS: MRI is accurate in the evaluation of parametrial invasion and lymph node metastases and in the differentiation of localized and advanced disease. MRI is beneficial in planning treatment for patients with cervical cancer.

Adult↗

PubMed2000

Aberrant cervical carotid artery.

Aberrant cervical carotid artery is an uncommon anomaly. Because this anomaly can lie in close proximity to the midline of the posterior part of the pharynx, it poses a significant risk during both major pharyngeal tumor resection and less extensive procedures such as tonsillectomy, adenoidectomy and palatopharyngoplasty. Five cases of aberrant cervical carotid artery were encountered and diagnosed using computerized tomography. In all five cases, the anomalous finding did not correlate with the presenting symptoms. Computerized tomographic images of these cases are provided. A review of the literature and the embryology of the aberrant carotid artery are presented. Awareness of the anomaly by radiologists and surgeons is essential to avoid accidental injury to the vessel during surgery.

Adult↗

PubMed2000

Double-balloon technique for embolization of carotid cavernous fistulas.

Embolization of a carotid cavernous fistula (CCF) by means of a detachable balloon is an established method for treating CCFs while preserving a patent parent internal carotid artery (ICA). However, failure to embolize the CCF may occur on a few occasions, such as when the balloon cannot pass through the fistula into the cavernous sinus by blood flow, or when the inflated balloon in the cavernous sinus retracts to the carotid artery. Under these circumstances, the ICA may have to be sacrificed in order to treat the CCF. Herein we describe a double-balloon technique for embolization of a CCF. By applying this technique, we successfully treated nine of 11 CCFs, without compromise of the parent ICA when the conventional one-balloon technique failed.

Balloon Occlusion↗

PubMed2000

Lack of association between angiotensin I-converting enzyme gene deletion polymorphism and cerebrovascular disease in Taiwanese.

BACKGROUND AND PURPOSE: Angiotensin I-converting enzyme (ACE) gene deletion polymorphism (D) has recently been suggested as a significant risk factor for cerebrovascular disease in studies involving Japanese and white populations. We investigated the role of ACE D polymorphism in the pathogenesis of cerebrovascular disease in Taiwanese. METHODS: To examine the association of ACE genotype and allele frequency with cerebrovascular disease, we conducted a study of 306 stroke patients and 300 control subjects matched by age and sex. RESULTS: Although the frequencies of both the homozygous deletion (DD) genotype and the D allele were greater in stroke patients than in control subjects, these differences were not significant. Further comparison of the frequencies of the DD genotype and the D allele in the three stroke subgroups (intracerebral hemorrhage, probable large-vessel disease, and probable small-vessel lacunar infarction) with the control group revealed no significant associations. Moreover, ACE gene polymorphism was not significantly associated with age of onset of stroke. Stepwise logistic regression analysis of the presence of the D allele and data on risk factors confirmed the lack of significant association between ACE deletion polymorphism and cerebrovascular disease. Moreover, no association was identified between ACE genotypes and any of the relative risk factors for cerebral infarction or severity of carotid atherosclerosis. CONCLUSIONS: Our results suggest that deletion polymorphism of the ACE gene is not associated with the pathogenesis of cerebrovascular disease in Taiwanese.

Alleles↗