Search PubMed⌕ Search

Biomedical subjects

L Y Chang

Publications and source records attributed to L Y Chang.

At least 19 recordsLinked to original sources
PubMed2006

Detecting genetic predisposition for complicated clinical outcomes after burn injury.

Sepsis, septic shock and organ failure are common among patients with moderate to severe burns. The inability of demographic and clinical factors to identify patients at high risk for such complications suggests that genetic variation may influence clinical outcome. Moreover, the genetic predisposition to death from infection has been estimated to be greater than for cardiovascular disease or cancer . While it is widely accepted that genetic factors influence many complex disease processes, controversy has emerged regarding the most appropriate methods for detection and even the validity of many published allelic associations . This article will review the few studies of genetic predisposition that have been conducted in the setting of burn injury, then discuss some of the obstacles and potential approaches for the discovery of additional allelic associations.

Burns↗
PubMed2006

HREM of the [111] surfaces of iron oxide nanoparticles.

Mixed phase Fe3O4-gamma-Fe2O3 (magnetite-maghemite) iron oxide nanoparticles have been fabricated by colloidal routes. HRTEM/HRSTEM images of the nanoparticles show the presence of [111] facets that terminate with enhanced contrast, which is shown to be caused by the presence of additional cations at the edges of the nanoparticles. HRTEM images were taken on a FEI CM200 FEGTEM, a JEOL 3100 with a LaB6 source, and a double aberration corrected JEOL-JEM 2200FS FEGTEM. The enhanced contrast effect was observed on the [111] surface atomic layers resolved using each machine. HRSTEM images, taken on an aberration corrected STEM, resolved enhanced contrast at specific surface sites. Exit wave reconstruction was also carried out on focal series taken on a double aberration corrected JEOL-JEM 2200FS and showed similar highly resolved enhanced contrast at specific surface cation sites. It is apparent that additional cations are occupying the [111] terminating layers of these nanoparticle surfaces. The use of different microscopes and techniques in this paper provides strong evidence that the enhanced contrast is a real effect and not an effect caused by microscope aberrations.

Journal Article↗
PubMed2006

Expression of a thermostable xylanase gene from Bacillus coagulans ST-6 in Lactococcus lactis.

AIMS: The aim of the study is to evaluate whether xylanase can be used as a potential reporter gene for cloning and expression studies in Lactococcus. METHODS AND RESULTS: The 750 bp xylanase gene was amplified and subcloned into the unique NheI restriction enzyme site of pMG36e and subsequently transformed into competent Escherichia coli XLI-blue MRF cells and Lactococcus lactis cells. Bacterial culture containing pMG36e-Xy has an enzyme activity of 390 microg xylose ml(-1) culture 30 min(-1), respectively, when compared with 40 microg xylose ml(-1) culture 30 min(-1) for the negative control (plasmidless strain). CONCLUSIONS: The thermostable xylanase gene was successfully expressed in both E. coli and L. lactis. The activity of xylanase can be easily detected by the formation of visible clearing zones around the transformed colonies on Remazol Brilliant Blue-Xylan (RBB-Xylan) agar media. However, there were some significant differences in the optimum growth temperature and plasmid stability in the new clones. SIGNIFICANCE AND IMPACT OF THE STUDY: The constructed reporter vector has the potential to be used as a reporter system for Lactococcus as well as E. coli, and it is an addition to the pool of lactococcal vector systems.

Bacillus↗
PubMed2005

On the importance of fifth-order spherical aberration for a fully corrected electron microscope.

Next generation aberration correctors will not only eliminate the third-order spherical aberration, but also improve the information limit by correction of chromatic aberration. As a result of these improvements, higher order aberrations, which have largely been neglected in image analysis, will become important. In this paper, we concern ourselves with situations where sub-A resolution can be achieved, and where the third-order spherical aberration is corrected and the fifth-order spherical aberration is measurable. We derive formulae to explore the maximum value of the fifth-order spherical aberration for directly interpretable imaging and discuss the optimum imaging conditions and their applicable range.

Journal Article↗
PubMed2005

Osteopontin gene expression in the aorta and the heart of propylthiouracil-induced hypothyroid mice.

It is known that there is abnormal osteopontin (OPN) expression at the sites of atherosclerotic lesions. In the Apolipoprotein E gene knockout (ApoE-KO) mouse, a model of the atherosclerotic process, altered cholesterol metabolism with associated increase in OPN expression is evident at 12-22 weeks in the aorta and at 22 weeks in the heart. In this study, we analyzed another animal model of hypothyroid mice created by ingestion of propylthiouracil (PTU). After 2 weeks of PTU ingestion, the animals had significant decreases in thyroid hormones (T3 and T4) and immediate increases in blood lipids/cholesterol. Hypothyroid mice showed 1.3-, 1.5-, 2-fold increases in blood levels of total cholesterol, triglycerides, and low density lipoprotein-cholesterol respectively. Semi-quantitative RT-PCR analysis showed that hypothyroid mice had 1.4- to 2-fold increases of OPN mRNA expression in the aorta and 1.5-fold increases in the heart. Hypothyroid animals treated with T3 (5 microg/day for 6 days) or statin (0.2 mg/30 g for 2 weeks) reduce blood lipids and aortic OPN mRNA expression. Data obtained with ELISA analyses showed 1.5- and 1.7-fold increases in OPN protein in the aorta (10 weeks) and the heart (22 weeks), respectively. This increase is close to the mRNA expression in both tissues of hypothyroid mice. In addition, western blots showed several variants of OPN protein expressed in the aorta and the heart. The decrease in the 70 kDa OPN is accompanied by an increase in 45 kDa OPN in the aorta of hypothyroid mice. In contrast, only 45 kDa OPN is found in the heart of control and hypothyroid mice. These data indicate that the increase of OPN mRNA and protein expression occurs in cardiovascular tissues of hypothyroid mice.

Animals↗
PubMed2005

Scoring system for empyema thoracis and help in management.

OBJECTIVE: To evaluate the implications of a newly defined severity scoring of empyema in children for the prediction of surgical management and to compare the length of hospitalization as an outcome measure of patients treated using medical therapy, salvage video-assisted thoracoscopic surgery (VATS) vs early elective VATS. METHODS: A retrospective chart review of parapneumonic empyema of patients below 18 years of age admitted to a tertiary children's hospital in northern Taiwan from April 1993 to December 2002 was performed. Patients were categorized into a medical group who received antibiotic therapy, needle aspirations with/without tube thoracostomy; a salvage VATS group when the patients required surgery for the relief of persistent fever > 38 degrees C, chest pains or dyspneic respirations despite initial medical therapy; an early VATS group when the patients received elective surgery early after admission. The demographic data, clinical features, laboratory findings, and duration of hospitalization were compared using a severity score of empyema (SSE). RESULTS: Streptococcus pneumoniae was the most common infecting organism, followed by Staphylococcus aureus, Pseudomonas aeruginosa. No organisms were recovered in 39% of patients. A pleural pH < 7.1 increases the odds of requiring surgical intervention by 6 times among this cohort. Children who required decortication of empyema had a higher severity score (mean 4.8 vs 3.0, p < 0.005). The duration of hospitalization for patients having early VATS showed a shortening stay (mean 18 vs 28 days) as compared to salvage VATS. CONCLUSION: A pleural pH < 7.1 and a newly designed clinical severity score of empyema 4 are two predictors of surgical intervention for fibrinopurulent empyema in the present study. Early elective VATS may be adopted not later than 7 days after failure of appropriate antibiotic therapy and adequate drainage of empyema to decrease the length of stay and minimize morbidity.

Adolescent↗
PubMed2005

Calculations of HREM image intensity using Monte Carlo integration.

We have developed a numerical approach for the accurate and efficient calculation of HREM image intensity formed using a partially coherent source. The approach is based on Monte Carlo integration, and is suitable for use in general image restoration methods using a series of images. The accuracy of this approach is compared with calculations based on the transmission cross coefficient (TCC) for strong scattering objects, as a function of the number of sampling points, defocus, atomic number and specimen thickness. Its efficiency is compared with that of exact TCC calculations based on equally-spaced sampling of the beam divergence and focal spread distributions. The results indicate that the Monte Carlo approach is particularly advantageous for nonlinear image restoration algorithms.

Journal Article↗
PubMed2002

Different proinflammatory reactions in fatal and non-fatal enterovirus 71 infections: implications for early recognition and therapy.

AIM: The mechanism of pulmonary oedema, a life-threatening manifestation of enterovirus 71 (EV71) encephalitis, is unclear. Our aim was to assess the relationship of proinflammatory cytokines to EV71-related pulmonary oedema. METHODS: Proinflammatory responses in 33 EV71 patients with various complications and 21 normal healthy children were measured using an enzyme-linked immunosorbent assay. RESULTS: EV71 patients with both encephalitis and pulmonary oedema were found to have much higher levels of blood interleukin-6 (IL-6) (947 +/- 1239 vs 4.9 +/- 3.1 pg/ml, p = 0.0003), tumour necrosis factor-alpha (TNF-alpha) (22.4 +/- 29.5 vs 5.3 +/- 1.0 pg/ml, p = 0.0035), interleukin Ibeta (IL-1beta) (48.4 +/- 85.2 vs 4.9 +/- 10.1 pg/ml, p = 0.01), white blood cell count (28.3 +/- 7.6 vs 15.5 +/- 6.8 10(9)/L, p > or = 0.0001) and blood glucose (501 +/- 186 vs 165 +/- 117 mg/dL, p = 0.0009) than patients with EV71 encephalitis alone. In fact, the cytokine levels in patients with encephalitis only or in those without complications were not significantly different from the levels found in normal children. The sensitivity, specificity, positive and negative predictive values of IL-6 > 70 pg/ml for EV71 encephalitis with pulmonary oedema were all 100%. CONCLUSION: Patients with EV71-related encephalitis combined with pulmonary oedema were found to have significantly elevated levels of proinflammatory cytokines and the best predictor for this complicated condition was found to be the level of serum IL-6.

Analysis of Variance↗
PubMed2001

DGT as an in situ tool for measuring radiocesium in natural waters.

The application of diffusive gradients in thin-films (DGT) samplers for the measurement of cesium radionuclides in solution, using an ammonium molybdophosphate (AMP) binding agent, was tested under both laboratory and field conditions. In the former they proved able to reproduce known 134Cs concentrations (60 Bq L(-1)) with a high degree of accuracy and precision over periods up to approximately 1 d, in freshwaters over a wide range of pH and temperature, and in saline water. In field trials in a freshwater lake receiving nuclear power station discharges, mean concentrations of 137CS (47-61 mBq L(-1)) were measured over periods from 5 d to 1 month. These agreed, within error, with mean concentrations determined from grab samples but rigorous field validation of long-term (month) deployments of DGT devices proved impossible using conventional sampling procedures, due to loss of 137Cs to container walls. Identified limitations of the DGT technique included probable AMP degradation over longer periods and calibration problems if large changes in temperature and concentration occurred together. Potential limitations due to biofilm growth were considered not to be significant. Despite the limitations, the technique appears to measure concentrations accurately for deployment times of 1 month or less. It has several advantages over traditional sampling methods for monitoring radionuclides in the solution/dissolved phase, including its simplicity, provision of time-averaged mean concentrations, and automatic in-situ concentration onto a medium with ideal counting geometry for gamma spectrometry.

Cesium Radioisotopes↗
PubMed2001

Normotopic and heterotopic cortical representations of mystacial vibrissae in rats with subcortical band heterotopia.

The tish rat is a neurological mutant exhibiting bilateral cortical heterotopia similar to those found in certain epileptic patients. Previous work has shown that thalamocortical fibers originating in the ventroposteromedial nucleus, which in normal animals segregate as 'barrel' representations for individual whiskers, terminate in both normotopic and heterotopic areas of the tish cortex (Schottler et al., 1998). Thalamocortical innervation terminates as barrels in layer IV and diffusely in layer VI of the normotopic area. Discrete patches of terminals are also observed in the underlying heterotopic area suggesting that representations of individual vibrissa may be present in the heterotopic somatosensory areas. The present study examines this issue by investigating the organization of the vibrissal somatosensory system in the tish cortex. Staining for cytochrome oxidase or Nissl substance reveals a normal complement of vibrissal barrels in the normotopic area of the tish cortex. Dense patches of cytochrome oxidase staining are also found in the underlying lateral portions of the heterotopic area (i.e. the same area that is innervated by the ventroposteromedial nucleus). Injections of retrograde tracers into vibrissal areas of either the normotopic or heterotopic area produce topographically organized labeling of neurons restricted to one or a small number of barreloids within the ventroposteromedial nucleus of the thalamus. Physical stimulation of a single whisker (D3 or E3) elicits enhanced uptake of [(14)C]2-deoxyglucose in restricted zones of both the normotopic and heterotopic areas, demonstrating that single whisker stimulation can increase functional activity in both normotopic and heterotopic neurons. These findings indicate that the barrels are intact in the normotopic area and are most consistent with the hypothesis that at least some of the individual vibrissae are 'dually' represented in normotopic and heterotopic positions in the primary somatosensory areas of the tish cortex.

Animals↗
PubMed2001

A 60-kilodalton immunodominant glycoprotein is essential for cell wall integrity and the maintenance of cell shape in Streptococcus mutans.

We have demonstrated previously by Western blotting that in naturally sensitized humans, the serum or salivary antibody response to Streptococcus mutans was directed predominantly to a protein antigen with a size of approximately 60-kDa. To identify this immunodominant antigen, specific serum antibodies were eluted from immunoblots and five positive clones with inserts ranging in length from 3 to 8 kb from identical chromosomal loci were obtained by screening a genomic expression library of Streptococcus mutans GS-5. Amino acid sequencing established the identity of this immunodominant antigen, a 60-kDa immunodominant glycoprotein (IDG-60), to be a cell wall-associated general stress protein GSP-781, which was originally predicted to have a molecular mass of approximately 45 kDa based on the derived nucleotide sequence. Discrepancy in the molecular mass was also observed in recombinant his-tagged IDG-60 (rIDG-60) expressed from Escherichia coli. Glycosylation, consisting of sialic acid, mannose galactose, and N-acetylgalactosamine, was detected by lectin binding to IDG-60 in cell wall extracts from S. mutans and rIDG-60 expressed in vivo or translated in vitro. Despite the presence of multiple Asn or Ser or Thr glycosylation sites, IDG-60 was resistant to the effect of N-glycosidase F and multiple O-glycosidase molecules but not to beta-galactosidase. Insertional inactivation of the gene encoding IDG-60, sagA, resulted in a retarded growth rate, destabilization of the cell wall, and pleiomorphic cell shape with multifold ingrowth of cell wall. In addition, distinct from the parental GS-5 strain, the isogenic mutant GS-51 was unable to survive the challenge of low pH and high osmotic pressure or high temperature. Expression of the wild-type gene in trans within GS-51 from plasmid pDL277 complemented the growth defect and restored normal cell shape. These results suggested that IDG-60 is essential for maintaining the integrity of the cell wall and the uniformity of cell shape, both of which are indispensable for bacteria survival under stress conditions.

Adult↗
PubMed2001

Glutamine protects mitochondrial structure and function in oxygen toxicity.

Glutamine is an important mitochondrial substrate implicated in the protection of cells from oxidant injury, but the mechanisms of its action are incompletely understood. Human pulmonary epithelial-like (A549) cells were exposed to 95% O2 for 4 days in the absence and presence of glutamine. Cell proliferation in normoxia was dependent on glutamine, and glutamine deprivation markedly accelerated cell death in hyperoxia. Glutamine significantly increased cellular ATP levels in normoxia and prevented the loss of ATP in hyperoxia seen in glutamine-deprived cells. Mitochondrial membrane potential as assessed by flow cytometry with chloromethyltetramethylrosamine was increased by glutamine in hyperoxia-exposed A549 cells, and a glutamine dose-dependent increase in mitochondrial membrane potential was detected. Glutamine-supplemented, hyperoxia-exposed cells had a higher O2 consumption rate and GSH content. Electron and fluorescence microscopy revealed that, in hyperoxia, glutamine protected cellular structures, especially mitochondria, from damage. In hyperoxia, activity of the tricarboxylic acid cycle enzyme alpha-ketoglutarate dehydrogenase was partially protected by its indirect substrate, glutamine, indicating a mechanism of mitochondrial protection.

Adenosine Triphosphate↗
PubMed2001

Attenuation of bleomycin-induced pulmonary fibrosis by a catalytic antioxidant metalloporphyrin.

Oxidative stress plays an important role in the development of fibrotic responses in the lung. However, it is not clear whether inhibiting oxidative stress with antioxidants can attenuate fibrotic processes in the lung. The objective of these studies was to test whether the catalytic antioxidant porphyrin manganese (III) tetrakis (4-benzoic acid) porphyrin (MnTBAP) could protect mice against bleomycin-induced lung fibrosis. A 10 mg/kg intraperitoneal dose of MnTBAP was established as safe and had a serum and lung half-life of 9.5 h in mice. Based on this data, four groups of mice were given one dose of bleomycin (3.2 U/kg, intratracheal) or saline and MnTBAP (5 mg/kg, intraperitoneal) or saline twice daily for 14 d. Lung fibrosis was assessed by measuring (1) lung hydroxyproline content as an index of collagen accumulation, (2) airway dysfunction by whole body plethysmography, and (3) histopathology. Bleomycin produced a 20% loss in body weight that was only 10% in the bleomycin/MnTBAP group. Bleomycin produced a twofold increase in hydroxyproline content that was decreased 23% by MnTBAP. Bleomycin produced a twofold increase in airway dysfunction that was also attenuated 30% by MnTBAP. Histopathologic analysis of the lungs of mice treated with bleomycin demonstrated a severe fibrotic response that was attenuated 28% by MnTBAP. Future studies on the oxidant mechanisms that MnTBAP is affecting in this bleomycin model of lung fibrosis may shed light on potential new therapeutic approaches for treating interstitial lung diseases.

Animals↗
PubMed2001

Duration of enterovirus shedding in stool.

Excretion of enterovirus (EV) may persist for months after an EV infection; the exact duration of excretion, however, is not yet known. Twelve children who were infected with EV between September 1998 and June 1999 were enrolled into this study. The patients included 4 boys and 8 girls, aged from 1 month to 5 years. Six patients were asked to join this virus isolation program, and the other 6 were followed-up regularly. Only 2 of the patients were infected with EV 71. To delineate the duration of EV shedding in each case, throat swabs for virus isolation were performed every 1 or 2 weeks for at least 1 month, and stools were analyzed for at least 2 months following the same schedule. After the infection, EV was identifiable in the throat in 4 patients for 1 to 2 weeks. Excretion of EV through stool was evidenced for up to 7 weeks in 6 patients, 8 weeks in 3, and 11 weeks in 1. In the 2 patients who failed to show up for follow-up visits from the 7th week, excretion of EV through stool was recorded for at least 7 weeks. Different serotypes of EV could be isolated from the same patient who was not experiencing febrile illness in 2 instances in a series of virus cultures. Coexistence of vaccine poliovirus and non-polio EV, both isolated from stool, was evidenced in 2 patients. Results from this study suggest that EV may not be identified from the throat 2 weeks after the infection, but its excretion through stool can persist for up to 11 weeks. This study also demonstrated that subclinical EV coinfection could occur, and that live vaccine poliovirus did not interfere with the invasion of other non-polio EV.

Child, Preschool↗
PubMed2001

Characteristics of group A streptococcal bacteremia with comparison between children and adults.

This retrospective study aimed to compare the characteristics of group A streptococcal bacteremia in children and adults. A total of 76 (12 children and 64 adults) patients with group A streptococcal bacteremia treated from October 1995 through September 2000 at the Linko Chang Gung Memorial Hospital were included. The mean age was 47.6 years (range, 12 days-90 years). Forty-four (57.9%) patients had predisposing medical conditions. Malignant cancer (23.7%) and diabetes (22.4%) were the 2 most common conditions, which occurred only in adults. Two (16.7%) children had chickenpox associated with secondary group A streptococcal bacteremia. Skin and soft tissue infection (60.5%) was the most common clinical manifestation. The mortality rate related to group A streptococcal bacteremia was 25%. Twelve patients met the criteria of streptococcal toxic shock syndrome and 6 (50%) were children (p<0.05). Despite immediate and aggressive treatment, mortality due to streptococcal toxic shock syndrome was 66.7%. The incidence of streptococcal toxic shock syndrome was much higher in children (50%) than in adults (9.4%). Early diagnosis of invasive group A streptococcal infections and streptococcal toxic shock syndrome requires awareness of the presentations and a high level of suspicion. For fulminant group A streptococcal infection, a combination of a beta-lactam antibiotic plus clindamycin and/or adjuvant therapy with intravenous immunoglobulin is recommended.

Adolescent↗
PubMed2001

Deep neck infections in children.

From December 1989 through 1998, a total of 68 children with deep neck infection were enrolled into this study. The mean age was 5.9 years (range, 1 month-15.8 years). Infections in the retropharyngeal space (36.7%) were most common, followed by parapharyngeal space (30.8%), peritonsillar space (20.6%), and submandibular space (11.9%). Fever, neck pain, and swelling were the most frequent symptoms. The most common pathogens were viridans streptococci (41%, 16/39) and Staphylococcus aureus (26%, 10/39). Other isolates included Prevotella spp., Veillonella spp., Klebsiella pneumoniae, Escherichia coli, Morganella spp., and Enterobacter spp. Mixed infection was found in 46% (18/39) of patients. The mean duration of hospitalization was 12.4 days (range, 2-45 days). Complete resolution was achieved in 61 (89.7%) children. Complications occurred in 7 patients, including recurrence, mediastinal spread, bacteremia, and suppurative thyroiditis; the patient with mediastinal spread plus bacteremia died. Five patients had congenital cyst and 4 of them had complications or recurrence/relapse. In conclusion, infections in the retropharyngeal space and polymicrobial infections were most common in deep neck infection of Taiwan children.

Anti-Bacterial Agents↗
PubMed2000

Functional complementation by wheat eIF2alpha in the yeast GCN2-mediated pathway.

Translational control by specific eIF2alpha phosphorylation on serine 51 has been characterized in all eukaryotes with the significant exception of plants. In order to evaluate the capability of plant eIF2alpha to functionally control translation, the wild type (51S) and a nonphosphorylatable mutant (51A) of wheat eIF2alpha were expressed in a yeast genetic system. Expression of either wheat protein did not handicap growth under conditions that repress the eIF2alpha phosphorylation pathway. However, under conditions that induce specific eIF2alpha phosphorylation only strains expressing wheat 51S were able to grow between 2 and 4 days. Growth was dependent upon activity of yeast eIF2alpha kinase GCN2 and resulted in the increased translation of GCN4. The association between plant eIF2alpha and yeast eIF2B is supported by their specific coimmunoprecipitation from transgenic yeast cells. These data support the similarity among eukaryotic translational initiation processes and strengthen the concept that plants may contain an eIF2alpha phosphorylation pathway.

DNA-Binding Proteins↗