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Y C Chang

Publications and source records attributed to Y C Chang.

At least 181 records · Page 10Linked to original sources
PubMed1997

Structure and biological activities of acapsular Cryptococcus neoformans 602 complemented with the CAP64 gene.

The extracellular polysaccharide capsule of Cryptococcus neoformans is a well-recognized virulence factor. Strain 602 is an acapsular clinical isolate of unknown serotype which has been widely used in studies of virulence and host-parasite interactions. In previous studies, strain 602 was compared with genetically unrelated strains of various serotypes because the wild-type equivalent of strain 602 was not available. We created an encapsulated strain, TYCC38-602, by transforming strain 602 with the CAP64 gene which was isolated from a serotype D strain. Serological tests and chemical analysis of the major polysaccharide capsule of TYCC38-602 indicated that strain 602 was originally derived from a serotype A strain. Restoration of the ability to produce a capsule enabled strain 602 to cause fatal infection in mice, whereas the acapsular strain 602 remained avirulent. Capsule-restored yeast cells of strain 602 activated the human complement system and bound C3 fragments in a manner that is characteristic of encapsulated cryptococci. In addition, the capsule in TYCC38-602 masked the ability of the organism to induce tumor necrosis factor alpha and subsequent nitric oxide synthase production in primed macrophage-like cells. These results indicate that the lack of capsule in strain 602 is the reason for its inability to cause fatal infection. Moreover, the acapsular phenotype accounts for differences in various biological activities of strain 602 compared to encapsulated strains. The results also indicate that the gene product of CAP64 does not contribute to serotype specificity of capsules in C. neoformans.

Animals↗
PubMed1997

A simple, secure and universal pancreaticojejunostomy following pancreaticoduodenectomy.

Although the operative mortality of pancreaticoduodenal resection has decreased recently, the operative morbidity resulting from a leaking pancreatic anastomosis remains high. We described our experience in 50 consecutive cases with a simple, secure end to side pancreaticojejunostomy. We used a paediatric nasogastric tube in the pancreatic remnant duct as a temporary external pancreatic drain. There were 29 men and 21 women ranging from 12 to 84 years with a median age of 61 years. Forty-two patients underwent a standard Whipple procedure and eight a pylorus preserving pancreaticoduodenectomy. Average operating time was 270 minutes with a range of 170 to 480 minutes. The pancreaticojejunostomy could be constructed in a mean of 8 minutes. Intraoperative blood loss ranged from 150 to 3500 mL with a mean of 910 mL. Twenty-five patients (50%) received no blood transfusion. The consistency of the pancreatic remnant was hard in 12 patients (24%) and normal in 38 patients (76%). The pancreatic duct was dilated (> 4 mm) in 15 patients (30%). There was no operative mortality and only three (6.0%) minor leaks from the pancreatic anastomosis which healed spontaneously. It was difficult to determine if the leaks were related to the consistency of the pancreatic remnant, the size of the pancreatic duct, the amount of intraoperative blood loss, operating time, sex of the patient or experience of the surgeon, as there were only three leaks. We concluded that our technique for pancreaticojejunal anastomosis following pancreaticoduodenectomy was safe and applicable to, standard Whipple or pylorus preserving pancreaticoduodenectomy, small or dilated pancreatic ducts, normal or fibrotic pancreas.

Adolescent↗
PubMed1997

Subtypes of ischemic stroke. A hospital-based stroke registry in Taiwan (SCAN-IV).

BACKGROUND AND PURPOSE: To better understand the clinical pattern and further elucidate the risk factors and outcome in different subtypes of cerebral infarction (CI) of the Chinese in Taiwan, we analyzed the National Taiwan University Hospital Stroke Registry in 1995 and performed an ethnic comparison with similar data banks. METHODS: From the National Taiwan University Hospital Stroke Registry in 1995, 676 patients (383 men and 293 women; mean age, 64.9 years; SD, 13.8 years; range, 1 to 98 years) with CI were recruited for this analysis. CI was classified into five subtypes based on clinical manifestations, ultrasonographic studies, and neuroimaging findings: large-artery atherosclerosis, lacunae, cardioembolism, other less common determined causes, and undetermined cause. Vascular risk factors, extracranial carotid artery atherosclerosis, and 30-day case-fatality rates were investigated in each subtype of CI. RESULTS: Of all CI patients, 17%, 29%, 20%, 6%, and 29% were classified as large-artery atherosclerosis, lacunae, cardioembolism, other determined causes, and undetermined cause subtypes, respectively. The present results were compared with those from eight similar Western stroke registries. The relative incidence of lacunar CI in Chinese patients was more common, but large-artery atherosclerotic CI was less common than in whites. Hypertension was frequently seen in CI patients, especially in those with lacunae (85%) and large-artery atherosclerosis (69%). Patients with cardioembolism had a higher percentage of atrial fibrillation (69%), left ventricular hypertrophy, and ischemic heart disease than the other patients. Patients with large-artery atherosclerosis had more vascular risk factors, such as hypertension, diabetes mellitus, smoking, and carotid stenosis. Cardioembolic patients had higher case-fatality rates than other CI patients. Of the cardioembolic patients, 17.3% and 21.8% died within 30 days and during hospitalization, respectively. CONCLUSIONS: The proportion of CI subtypes varied in different stroke registries. This may be partly due to applied classification criteria and racial-ethnic differences. Awareness of the risk factors and outcome in each subtype of stroke may afford further insights into the surveillance and treatment of cerebrovascular disease.

Adolescent↗
PubMed1997

Environmental risk factors and Parkinson's disease: a case-control study in Taiwan.

To explore environmental risk factors for Parkinson's disease (PD) in Taiwan, we investigated 120 patients with PD and 240 hospital control subjects matched with patients on age (+/-2 years) and sex. Based on a structured open-ended questionnaire, we carried out standardized interviews to obtain history of exposure to environmental factors, including place of residence, source of drinking water, and environmental and occupational exposures to various agricultural chemicals. In the univariate analysis, the history of living in a rural environment, farming, use of herbicides/pesticides, and use of paraquat were associated with an increased PD risk in a dose-response relationship. After adjustment for multiple risk factors through conditional logistic regression, the biological gradient between PD and previous uses of herbicides/pesticides and paraquat remained significant. The PD risk was greater among subjects who had used paraquat and other herbicides/pesticides than those who had used herbicides/pesticides other than paraquat. There were no significant differences in occupational exposures to chemicals, heavy metals, and minerals between PD patients and matched control subjects. The duration of drinking well water and alcohol consumption was not significantly associated with PD. There was an inverse relationship between cigarette smoking and PD. Environmental factors, especially exposures to paraquat and herbicides/pesticides, may play important roles in the development of PD in Taiwan.

Adult↗
PubMed1997

Prenatal diagnosis of a deletion of 18q in a fetus associated with multiple-marker screen positive results.

We report here the observations of positive maternal serum screening tests for Down syndrome, cytogenetic and molecular analysis, and dysmorphic fetal features in a pregnancy with 18q-syndrome. A 33-year-old primigravida was referred for genetic counselling because of multiple-marker screen positive results. At 14 weeks' gestation, the woman had a Down syndrome risk of 1:107 calculated from a maternal serum alpha-fetoprotein (MSAFP) level of 1.49 multiples of the median (MOM), a total human chorionic gonadotrophin (hCG) level of 2.42 MOM, and a serum unconjugated oestriol (uE3) level of 0.55 MOM. At 17 weeks' gestation, a repeat test showed a Down syndrome risk of 1:10 calculated from an MSAFP level of 1.09 MOM and a free beta-hCG level of 12.3 MOM. Genetic amniocentesis revealed a de novo deletion of 18q22.2-qter. Intrauterine fetal death occurred at 21 weeks' gestation. At birth, the fetus manifested clinical findings of the 18q-syndrome. The phenotype was correlated with the extent of the deletion. Linkage analysis of the family confirmed the extent and paternal origin of the deletion.

Adult↗
PubMed1996

A study of the oligomeric state of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-preferring glutamate receptors in the synaptic junctions of porcine brain.

The number of the subunits in an alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-preferring L-glutamate receptor in the synaptic junctions of porcine brain was investigated in this study. Upon incubation of the synaptic junctions with three cross-linking regents, dimethyl adipimidate (DMA), dimethyl suberimidate (DMS) and N-succinimidyl-(4-azidophenyl)-1,3'-dithiopropionate (SADP), AMPA receptor subunits in higher-molecular-mass aggregates were detected by immunoblotting. These aggregates migrated as proteins of approx. 200, 300 and 400 kDa. The number and identity of the subunits in a solubilized AMPA receptor were also investigated here. Two samples, W1 and W2, enriched in AMPA receptors were prepared from synaptic junctions by a combination of detergent-solubilization, anion-exchange chromatography and wheatgerm agglutinin affinity chromatography. Hydrodynamic behaviour analyses revealed that the majority of the AMPA receptors in either one of these samples were asymmetrical detergent-surrounded particles with a protein mass around 350 kDa. SDS/PAGE analysis revealed that the majority of AMPA receptors in the W1 sample were comprised of dimers of 106 kDa subunits which were covalently linked by disulphide bonds. Cross-linking these receptors with SADP yielded a new band of approx. 400 kDa. The results obtained here, either from the studies of AMPA receptors embedding in synaptic junctions or from those of detergent-solubilized and partially purified receptors, suggest that AMPA receptors contain a basic core structure comprising of four 106 kDa subunits.

Animals↗
PubMed1996

Clinicopathologic, cytogenetic, and molecular studies of 13 Chinese Patients with Ki-1 anaplastic large cell lymphoma. Special emphasis on the tumor response to 13-cis retinoic acid.

BACKGROUND: The clinicopathologic and molecular features of the newly characterized Ki-1 lymphoma, although well studied in Western countries, are less well described in Asia. METHODS: Pathology material of lymphoma cases, consecutively diagnosed at our institution between 1986 and 1994, was reviewed. The cases fulfilling the diagnostic criteria of Ki-1 lymphoma were selected, and their clinicopathologic features were studied. Immunohistochemistry and cytogenetic studies of the lymphoma tissues, and molecular analysis for nucleophosmin (NPM) gene translocation were performed. RESULTS: A total of 13 cases (2.3%) of Ki-1 large cell lymphoma were identified from a total of 572 cases of non-Hodgkin's lymphoma diagnosed during this period of time. There were 10 men and 3 women with a median age of 43 years (range, 18 to 61 years). The initial presenting sites included the skin alone in five cases, lymph node alone in one case, both skin and lymph node in five cases, and the stomach in one case. All cases had large cell morphology, with the majority of the neoplastic cells expressing Ki-1 antigen (CD30). Except for the case with gastric involvement, all other cases were T-cell lymphomas. One of seven cases examined had chromosomal abnormality of t (2;5). Rearrangement of the NPM gene at chromosome 5 was detected by Southern blot analysis in three of nine cases. Two of seven cases tested by reverse-transcriptase polymerase chain reaction showed fusion of the NPM gene and anaplastic lymphoma kinase gene. Seven (78%) of 9 patients who had received systemic chemotherapy with a standard cyclophosphamide, doxorubicin, vincristine, and prednisolone regimen obtained a complete remission (CR). The median duration of remission was 33 months. Three (60%) of 5 patients, of whom 4 recurred from previous intensive chemotherapy, achieved a prolonged CR with treatment with 13-cis retinoic acid (RA). The median survival of the whole group has not yet been reached at a median follow-up of 40 months. CONCLUSIONS: The clinicopathologic and molecular features of Ki-1 lymphoma of Chinese patients are comparable to those reported from Western countries. 13-cis RA appears to be an effective treatment of Ki-1 lymphoma.

Adult↗
PubMed1996

Purification and biochemical characterization of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainate-sensitive L-glutamate receptors of pig brain.

Two preparations of glutamate receptors were purified from the synaptic junctions of pig brain by a combination of detergent solubilization, anion-exchange chromatography, wheat-germ agglutinin affinity chromatography and sedimentation through sucrose gradients. These preparations were enriched in specific L-[3H]glutamate binding activity (> 5000 pmol of glutamate binding sites/mg of protein), and the rank order of ligand affinity for binding to these preparations was: quisqualate > 6-cyano-7- nitroquinoxaline-2,3-dione > alpha-amino-3-hydroxy-5-methyl-4- isoxazolepropionic acid (AMPA) > L-glutamate > kainate > > N-methyl-D-aspartate approximately L-2-amino-4-phosphonobutyrate. SDS/PAGE analysis revealed that more than 80% of the protein in either of these preparations appeared as a single protein band of 106 kDa. Two-dimensional gel electrophoresis further revealed that these 106 kDa proteins consisted of a series of acidic proteins which were recognized by antibodies against rat AMPA receptor subunits. These 106 kDa proteins were also recognized by wheatgerm agglutinin and concanavalin A; in addition, peptide N-glycosidase F treatment of these preparations decreased their size to 99 kDa. Our results suggest that the putative glutamate receptors isolated here are likely to belong to the AMPA subtype of glutamate receptors in pig brain. Using the purification procedure reported here, 5 micrograms of AMPA receptor proteins can be isolated from 250 g of pig brain tissue.

Animals↗
PubMed1996

Is ataxic gait the predominant presenting manifestation of Creutzfeldt-Jakob disease? Experience of 14 Chinese cases from Taiwan.

Creutzfeldt-Jakob disease (CJD) is caused by an unusual prion protein. Rare CJD cases have been reported in Chinese individuals. This report describes the clinical manifestations of 14 Chinese individuals with clinically definite CJD from the National Taiwan University Hospital during the period 1976-1995. It is the largest case series of Chinese CJD up to now. All these patients fulfil the clinical definite diagnosis of CJD proposed by Brown et al. (1986), including rapidly evolving dementia, myoclonus, periodic electroencephalographic (EEG) activity (0.5-2 Hz) and death within 12 months. The clinical characteristics of the present series, including age at onset, sex ratio, duration, initial symptoms, neurological signs, EEG abnormalities, and neuroimaging studies were similar to those reported in other countries. However, there is a high incidence of initial ataxic gait as the presentation in our patients. Eight (57%) out of 14 patients initially had gait ataxia alone or in association with dementia. CJD should be considered in the differential provisional diagnosis of any middle-aged patient with a progressive ataxic syndrome.

Aged↗
PubMed1996

Renal neural response to ischemic renal failure in chronic hypoxic rats.

This report was designed to assess response of the renal nerve activity (RNA) during and after renal ischemia in chronic hypoxic rats. Hypoxia was induced by placing the female Wistar rats in an altitude chamber set at 5500 m for 4 weeks. Simultaneous recordings of left renal efferent (RENA) and afferent (RANA) nerve activity were performed in each pentobarbital-anesthetized rat throughout the experiment. Ischemic renal failure was induced by complete occlusion of the left renal artery for 45 min. During renal arterial occlusion (RAO), RENA gradually decreased while RANA enhanced initially and then this decreased gradually in both sea level (SL) controls and chronic hypoxic (high-altitude; HA) rats. During 45 min of reperfusion, RENA depressed more in comparison with RANA in both groups of animals. In addition, RANA returned to baseline level in SL rats, while it remained elevated in HA rats. In the second experiment, six groups of renal ischemic rats were challenged by rapid intravenous infusion of 10 ml of saline, and urine was collected for 90 min from the left ureter. Baseline RENA was low in rats 4 h after RAO of SL (4SL) and of HA (4HA) groups. The effects of saline loading on RENA and RANA were different in HA and SL rats. Saline loading significantly decreased RENA but increased RANA more in SL rats. Following saline loading, RENA in 4SL and 4HA rats, as well as animals 24 h after RAO of SL (24SL) and HA (24HA) were comparable to their respective SL or HA animals. In 4SL rats, RANA was significantly enhanced, and remained elevated during saline loading and the recovery period. In 4HA, 24HA and 24SL rats, RANA reduced significantly during saline loading, then its activity returned to the baseline value. The insulted kidneys showed increased renal excretion of water and sodium in 4SL and 4HA rats. Urinary excretion reduced significantly in 24SL rats but was almost normal in 24HA rats. These results indicate that a decrease in RENA may play a protective role in response to renal ischemia in both SL and HA rats. In response to renal ischemia and saline loading, different alterations of RANA in SL and HA rats may reflect a beneficial mechanism located in the hypoxia-pretreated kidney.

Animals↗
PubMed1996

Secretion of active subtilisin YaB by a simultaneous expression of separate pre-pro and pre-mature polypeptides in Bacillus subtilis.

Alkaline elastase YaB, produced by alkalophilic Bacillus YaB, is an extracellular serine protease having 55% homology to subtilisin BPN' and thus could be called subtilisin YaB. It is synthesized as a 378-amino acid preproenzyme and secreted into the culture medium as a 265-amino acid mature protease. To examine if the pro-peptide of subtilisin YaB functions in trans to guide the folding of secreted subtilisin YaB in vivo, we made genes encoding the pre-pro, pro and pre-mature portions and placed them under the control of the spac-1 promoter on a multi-copy plasmid. When simultaneous expression in Bacillus subtilis of both the pre-pro and pre-mature genes was induced with 0.5 mM isopropyl-1-thio-beta-D-galactopyranoside (IPTG), protease activity was detected in the medium. On the other hand, we could not detect protease activity when the expression of either the pre-mature gene alone or both the pro and pre-mature genes was induced. From these results, we concluded that the pro region functions in trans and outside the cells for the proper folding and activation of the enzyme.

Bacillus subtilis↗
PubMed1996

Comparison of skeletal muscle microcirculation between clamp ischemia and microsurgical ischemia.

We compared ischemia reperfusion injury-associated vasospasm and perfused capillary density (PCD) at the microcirculatory level between clamp ischemia and microsurgical ischemia in rat skeletal muscle. Rat cremaster muscle was prepared as an island flap, attached only with pudic-epigastric vessels branching from external iliac vessels. Two types of ischemia, with clamping only or with microvascular anastomosis, were applied at the external iliac vessels for 2 hours followed by 1-hour reperfusion before in vivo microscopic examination for hemodynamic changes. At the end of observation, small segments of the vessels at the clamping site and microsurgical anastomoses site were also harvested for histological examination. It was found that the first- and second-order arterioles had about 12-15% diameter reductions in both groups, whereas diameter reductions of the third-order arterioles were up to 37.8% in the microsurgical ischemia group, much greater than that in the clamp ischemia group (2.3%). There was also no significant difference in PCD reduction between the two groups, although the red blood cell velocity was much slower in the microsurgical ischemia group. Histological examination of the anastomosis site showed massive accumulation of polymorphonuclear neutrophils on the venous endothelium. These results suggested a different degree of endothelial damage and local leukocyte activation between microsurgical ischemia and clamp ischemia. Therefore, we conclude that clamp ischemia cannot replace microsurgical ischemia for studying microcirculatory changes in free tissue transfer.

Anastomosis, Surgical↗
PubMed1996

Effects of paraquat on the substantia nigra of the wistar rats: neurochemical, histological, and behavioral studies.

Effects of paraquat on the substantia nigra of the male Wistar rats we re studied pharmacologically by a intracerebral injection of paraquat. The neurochemical, morphological, and behavioral changes observed after a unilateral intranigral injection of paraquat (1-5 microgram) were as follows: (1) neurochemically, paraquat caused dose-dependent depletion of dopamine in the ipsilateral striatum starting 2 weeks after treatment; this effect was long-lasting and irreversible. The ipsilateral striatal dopamine level in animals treated with 3 microgram paraquat was even decreased by 91.5%. (2) Morphologically, 2 microgram of paraquat produced marked loss of Nissl substances and prominent glial reaction in the substantia nigra, while 3 microgram of paraquat caused a severe loss of neurons. (3) Behaviorally, paraquat caused a vigorous rotational behavior in rats contralateral to the lesioned side in response to apomorphine administration (0.5 mg/kg, sc). This effect was dose-dependent and lasted for the entire 16-week experimental period. Taken together, these data indicate that intranigrally injected paraquat may possess marked neurotoxicity and induce degeneration of the rat nigrostriatal dopaminergic system.

Animals↗
PubMed1996

Epidermal denervation and its effects on keratinocytes and Langerhans cells.

Skin innervation has been considered to subserve sensory perception only, but several lines of evidence suggest that there are "effector' influences of skin innervation on the immune system and keratotinocytes. In this study, we transected the sciatic nerves of rats and examined the effects of denervation on the epidermis. In normal skin, the epidermis was densely innervated by fine axons that were immunostained with several axonal markers, including neuronal ubiquitin carboxyl terminal hydrolase (protein gene product 9.5). All of the epidermal axons in the regions innervated by sciatic nerve disappeared within 24-48 h after transection of sciatic nerve, and remained absent as long as subsequent reinnervation by regenerating axonal sprouts was prevented. Denervation produced changes in both the keratinocytes and the Langerhans cells, the bone marrow-derived antigen-presenting cells of the epidermis. The thickness of epidermis decreased within 7 days. By 48 h after transection, the Langerhans cells and their dendritic processes became intensely immunoreactive for protein gene product. Protein gene product 9.5 expression on Langerhans cells remained prominent as long as skin was denervated, but disappeared with reinnervation. By reverse transcription-polymerase chain reaction, we demonstrated the presence of the transcripts for protein gene product 9.5 in epidermis, consistent with the synthesis of the protein by the Langerhans cells. We conclude that epidermal sensory fibres have novel influences on both keratinocytes and Langerhans cells of the epidermis.

Animals↗
PubMed1996

Molecular cloning of a cDNA encoding enolase from the filamentous fungus, Aspergillus oryzae.

A 1.6-kbp full-length cDNA for the Aspergillus oryzae enolase gene (enoA) was cloned. The sequenced insert contained a continuous open reading frame of 1314 bp encoding a protein of molecular weight 47 405. Among all enolases sequenced to-date, the deduced amino-acid sequence showed the highest homology (74.9%) with Candida albicans enolase (ENO1). Strong codon biases and multiple transcription start sites downstream from CT-blocks in the 5'-flanking region suggested strong expression. enoA mRNA was found to occupy approximately 3% (w/w) of total mRNA of A. oryzae by quantitative RT-PCR. This strong transcription was dependent on the carbon source in the medium and correlated with the growth rate of the mycelium.

Amino Acid Sequence↗
PubMed1996

Assaying the activity of HIV-1 integrase with DNA-coated plates.

Integration of reverse transcribed viral DNA of HIV into host chromosomes is mediated by the viral enzyme, integrase. This enzymatic activity can be monitored in vitro by integration of a small labeled DNA (donor) into a second unlabeled DNA (target). The methodology usually involves isotope labeling and gel electrophoresis. To simplify the measurement, a method mimicking enzyme-linked immunosorbent assay (ELISA) procedures was developed. Fragments of DNA were adsorbed directly on 96-well plates and used as the target DNA. The donor was a synthetic 21-bp DNA duplex of HIV-1 U5 LTR; biotin was incorporated into the 5' end of one strand whose two nucleotides at the 3' end were specifically removed during the integration. As a result of integration, the biotin-labeled donor DNA was joined with the target DNA and became immobilized on plates. These integration products were then measured by binding of avidin-alkaline phosphatase on plates. The method is simple and straightforward and can easily be adapted for high throughput screening of integrase inhibitors.

DNA↗
PubMed1996

Effects of castration and androgen replacement on tumour growth of human hepatocellular carcinoma in nude mice.

BACKGROUND/AIMS: Previous clinical investigations suggest that androgen and its receptor (AR) may play an important role in the growth of hepatocellular carcinoma. Few studies are available concerning the effect of androgen manipulation on the growth of AR-positive hepatocellular carcinoma in vivo. METHODS: AR-positive (SM10) and AR-negative (SM2) sublines derived from a human hepatocellular carcinoma line KYN-1 were implanted subcutaneously in the lower abdomen of nude mice. The tumour size and expression of proliferating cell nuclear antigen and Lewis Y antigen were examined in intact males, castrated males, intact females, and castrated males with androgen replacement. AR of the tumour was measured with binding assay, ultracentrifugation, and Western blotting. RESULTS: The growth of SM10 was significantly better in intact males and castrated males with 5a-dihydrotestosterone injection than in intact females and castrated males. Castration did not suppress the growth of SM2. The tumour AR level was reduced by castration but maintained by the hormone substitution. Although proliferating cell nuclear antigen expression was closely associated with tumour growth, Lewis Y antigen expression did not differ among the groups. CONCLUSIONS: These data may indicate that this hepatocellular carcinoma subline (SM10) is androgen-responsive and that androgen ablation can cause the inhibition of the tumour growth, which might be due to decreased proliferative and not increased apoptotic activities. In addition, such androgen-stimulated tumour growth seems to be mediated through AR.

Androgens↗