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Biomedical subjects

C M Chen

Publications and source records attributed to C M Chen.

At least 55 records · Page 3Linked to original sources
PubMed2001

Microsomal monooxygenase activity in Tilapia (Oreochromis mossambicus) exposed to a bleached kraft mill effluent using different exposure systems.

Bleached kraft pulp and paper mill effluents (BKMEs) are known to have adverse effects on aquatic organisms. One of the effects of BKMEs is its ability to induce cytochrome P4501A activity in exposed fish. 7-Ethoxyresorufin O-deethylase (EROD) activity is the most common biomarker used to measure the mixed-function monooxygenase activity. In this study, Tilapia were exposed to BKMEs using different exposure systems and their hepatic EROD activity, as well as liver/somatic index (LSI), were determined. In the Phase I study, Tilapia treated with betaNF and a whole (100%) BKME using a static, non-renewal system exhibited statistically significant EROD induction, but LSI values were not altered. In the Phase II study, fish were either caged in the mill's fishpond with the whole effluent passing through or cultured in tanks receiving 100% of the BKME continuously using a flow-through system in the laboratory. Their EROD activities were then compared with the non-exposed fish (control). The EROD activities in both groups of fish were elevated significantly with the greatest induction being observed in the field-exposed group. The LSI values in all of the field-exposed fish were significantly greater than the control Tilapia. The EROD assay was sensitive in detecting biological changes in fish exposed to the BKME. Further studies are warranted to better understand the impacts of BKMEs on aquatic organisms in Taiwan.

Animals↗
PubMed2001

A textural approach based on Gabor functions for texture edge detection in ultrasound images.

Edge detection is an important, but difficult, step in quantitative ultrasound (US) image analysis. In this paper, we present a new textural approach for detecting a class of edges in US images; namely, the texture edges with a weak regional mean gray-level difference (RMGD) between adjacent regions. The proposed approach comprises a vision model-based texture edge detector using Gabor functions and a new texture-enhancement scheme. The experimental results on the synthetic edge images have shown that the performances of the four tested textural and nontextural edge detectors are about 20%-95% worse than that of the proposed approach. Moreover, the texture enhancement may improve the performance of the proposed texture edge detector by as much as 40%. The experiments on 20 clinical US images have shown that the proposed approach can find reasonable edges for real objects of interest with the performance of 0.4 +/- 0.08 in terms of the Pratt's figure.

Algorithms↗
PubMed2001

A dual-snake model of high penetrability for ultrasound image boundary extraction.

Most deformable models require the initial contour to be placed close to the boundary of the object of interest for boundary extraction of ultrasound (US) images, which is impractical in many clinical applications. To allow a distant initial contour, a new dual-snake model promising high penetrability through the interference of the noises is proposed in this paper. The proposed dual-snake model features a new far-reaching external force, called the discrete gradient flow, a connected component-weighted image force, and an effective stability evaluation of two underlying snakes. The experimental results show that, with a distant initial contour, the mean distance from the derived boundary to the desired boundary is less than 1.4 pixels, and most snake elements are within 2.7 pixels of the desired boundaries for the synthetic images with CNR > or =1. For the clinical US images, the mean distance is less than 1.9 pixels, and most snake elements are within 3 pixels of the desired boundaries.

Algorithms↗
PubMed2001

Constituents of the root bark of Severinia buxifolia collected in Hainan.

Two new tetranortriterpenoids, 7-isovaleroylcycloseverinolide (1) and 7-isovaleroylcycloepiatalantin (2), together with 28 known compounds, were isolated and characterized from the root bark of Severinia buxifolia collected in Hainan. The structures of 1 and 2 were elucidated on the basis of spectral evidence including 2D NMR and X-ray techniques. The cytotoxicity of several acridone alkaloid isolates (3-8) was evaluated against a small tumor cell panel.

Acridines↗
PubMed2001

Prosthetic patch durability in congenital diaphragmatic hernia: a long-term follow-up study.

BACKGROUND/PURPOSE: The purpose of this study is to assess the durability of prosthetic patch repair of congenital diaphragmatic hernia (CDH) over time. METHODS: The authors retrospectively reviewed the records of 109 children who had surgical repair of CDH between January 1989 and December 1996. Prosthetic patches were used for diaphragmatic agenesis or when the diaphragmatic defect was too large for primary closure after mobilizing the posterior leaf. Forty-five (41%) children required a prosthetic patch to repair the diaphragmatic defect, and 29 (64%) of these children survived. RESULTS: Twelve (41%) of the 29 survivors required 1 or more operations for diaphragmatic reherniation. First-time reherniations occurred between 1 and 36 months postoperatively, median, 12 months. There was a bimodal distribution of first-time reherniations, with 4 children experiencing reherniation between 1 and 3 months, median age, 2 months and 8 children experiencing reherniation between 10 and 36 months, median age, 20 months. Three children returned for surgical repair of second reherniation between 21 and 39 months. Patients who had reherniation presented with bowel obstruction (n = 7), respiratory distress (n = 2), or were asymptomatic (n = 3). Revision of the reherniated patch consisted of placing an additional domed patch to fill the defect. CONCLUSIONS: About half of all prosthetic patches used to repair CDH show evidence of reherniation and require revision within 3 years. Prosthetic patch repair is not a long-term solution for the child with CDH.

Female↗
PubMed2001

The effect of hydration on adsorption and desorption of heavy metals in soils.

Cr, Ni, and Cd adsorption-desorption on five characterized Taiwan soils was studied. The potential for toxicity and the fate of metals in the soils is dependent upon the ability of the metals to desorb into the aqueous phase. To simulate field conditions, the soils were subjected to wet-dry cycles. The amount and rate of desorption was found to decrease with increasing number of cycles. The wet-dry cycle effect in the desorption of metals from soils is related to the soil composition, with desorption being easiest from sandy soil with low organic content. The desorption process is much slower than adsorption process. More than 95% of each metal adsorption takes place within one hour, and the amount of metal adsorbed from solution reached equilibrium in one day. In contrast, less than 20% metal desorption could be attained after 3 days each of four wet-dry cycles for Cr, Ni, and Cd.

Adsorption↗
PubMed2001

Surfactant and corticosteroid effects on lung function in a rat model of acute lung injury.

OBJECTIVES: To evaluate pulmonary responses to intratracheal administration of surfactant with and without dexamethasone in rats with paraquat-induced lung injury. DESIGN: Prospective, randomized, controlled study. SETTING: University research facility. SUBJECTS: Adult male Sprague Dawley rats. INTERVENTIONS: Rats were anesthetized and underwent a tracheostomy and arterial catheter insertion 3 days after intraperitoneal injection of paraquat (35 mg/kg). The rats were ventilated for 90 mins after sequential designation as controls or as recipients of intratracheal surfactant alone (50 or 100 mg/kg) or surfactant (50 or 100 mg/kg) plus dexamethasone (0.5 mg/kg). MEASUREMENTS AND MAIN RESULTS: Arterial blood gases were determined at 15, 30, 60, and 90 mins. After 90 mins of ventilation, a static pressure-volume curve was performed, and inflammatory cells, total protein content, and cytokines were measured in bronchoalveolar lavage fluid. Postmortem histology was then examined. Treatment with 50 mg/kg dexamethasone/Survanta and 100 mg/kg Survanta with and without dexamethasone significantly increased oxygenation shortly after instillation when compared with the control group, with the response maintained throughout the study period. Static pressure-volume curves showed that the group receiving 100 mg/kg dexamethasone/Survanta had significantly higher lung volumes than the control group. Total cell, neutrophil, and macrophage counts were decreased significantly in the animals treated with 100 mg/kg dexamethasone/Survanta compared with untreated control rats. Total protein recovered from bronchoalveolar lavage fluid in the animals treated with 100 mg/kg Survanta with and without dexamethasone was decreased significantly compared with control animals. The histologic appearance of the lungs was markedly better in the groups treated with surfactant with or without dexamethasone. CONCLUSIONS: Results suggest that the combined administration of high doses of intratracheal surfactant and dexamethasone improves gas exchange, ameliorates lung inflammation, and alleviates lung damage after paraquat-induced lung injury. Surfactant alone and lower doses of surfactant plus dexamethasone had a lesser effect on these measures.

Animals↗
PubMed2001

Clinical validation of the related factors and defining characteristics of impaired swallowing for patients with stroke.

This exploratory study was conducted to examine the reliability and validity of related factors and defining characteristics of impaired swallowing for stroke patients. Sample of the study included (1) 12 nursing experts, (2) 52 nurses who work in neurological wards, and (3) 107 stroke patients who were divided into a BDST (Burks Dysphagia Screening Test)-positive group (n = 51) and a BDST-negative group (n = 56). Data were collected and validated based on expert validity, diagnostic content validity (DCV), construct validity, and discriminate validity. Results showed that the DCV scores of 17 related factors and 12 defining characteristics were all greater than 0.5. The internal consistency of the 12 defining characteristics was demonstrated by a Cronbach alpha coefficient of 0.89. Two factors were extracted from the 12 defining characteristics after factor analysis; these were "high risk of aspiration with speech disorder" and "ineffectiveness of swallowing". Five major defining characteristics, i.e. pocketing of food, signs of acute aspiration, burning or tickling at the back of the throat, spitting food or food leaking from the mouth, and weak or hoarse cough, were determined by logistic regression. The findings of this study suggest that the 17 related factors and 12 defining characteristics are reliable and valid in diagnosing the problem of impaired swallowing for stroke patients.

Aged↗
PubMed2001

Selection and characterization of varicella-zoster virus variants resistant to (R)-9-[4-hydroxy-2-(hydroxymethy)butyl]guanine.

(R)-9-[4-Hydroxy-2-(hydroxymethy)butyl]guanine (H2G) is a potent and selective inhibitor of herpesvirus replication. It is a nucleoside analog, and its triphosphate derivative (H2G-TP) is a competitive inhibitor of herpesvirus DNA polymerases. In this study, the antiviral activities of H2G and acyclovir (ACV) and the development of viral resistance to these agents were compared in varicella-zoster virus (VZV)-infected cells. In plaque reduction assays, the 50% effective concentration of H2G for VZV was 60- to 400-fold lower than that of ACV, depending on the virus strain and the cell line tested. The enhanced efficacy of H2G against VZV can be accounted for in part by the fact that the intaracellular H2G-TP level (>170 pmol/10(6) cells) is higher than the intracellular ACV-TP level (<1 pmol/10(6) cells). In addition, H2G-TP has extended half-lives of 3.9 and 8.6 h in VZV-infected MRC-5 and MeWo cells, respectively. To assess the emergence of H2G-resistant VZV in vitro, VZV was passaged in the presence of increasing concentrations of H2G. Earlier in the passage, when the concentration of H2G was relatively low, the predominant variant had the (A)76 deletion in the viral thymidine kinase (TK) gene. This mutant was identical to an ACV-resistant mutant generated in parallel experiments. However, higher concentrations of H2G appeared to favor a novel mutant, which had deletions of two consecutive nucleotides at positions 805 and 806 of the TK gene. All of these changes introduced frameshift mutations in the TK gene resulting in the expression of truncated polypeptides. H2G-resistant viruses were cross-resistant to ACV, and vice versa.

Acyclovir↗
PubMed2001

Cefuroxime-impregnated cement at primary total knee arthroplasty in diabetes mellitus. A prospective, randomised study.

We have performed a prospective single-blinded randomised study to evaluate the role of antibiotic-impregnated cement in the prevention of deep infection at primary total knee arthroplasty (TKA) in patients with diabetes mellitus. We studied prospectively 78 arthroplasties performed for osteoarthritis in such patients. They were randomly separated into two groups. In group 1 (41 knees), cefuroxime-impregnated cement was used while in group 2 (37 knees) cefuroxime was not added to the cement. The preoperative, intraoperative and postoperative management was the same for both groups. The mean follow-up was 50 months (26 to 88). There were no cases of deep infection in group 1, but five (13.5%) occurred in group 2 (p = 0.021). We conclude that cefuroxime-impregnated cement is effective in the prevention of deep infection at primary TKA in patients with diabetes mellitus.

Aged↗
PubMed2001

Effect of rennet coagulation time on composition, yield, and quality of reduced-fat cheddar cheese.

This study compared the effect of coagulum firmness at cutting on composition of 50% reduced-fat Cheddar cheese. Coagulum firmness was determined by subjective evaluation by the cheese maker. Three firmness levels were tested, and these corresponded to average times of coagulant addition to cutting the curd of 25, 48, and 65 min. A slow acid-producing culture was used, and ripening times were altered to give similar curd pH values throughout cheese making. A longer rennet coagulation time (firmer coagulum at cutting) resulted in an increase in cheese moisture as well as an increase in cheese yield. The percentages of fat recovered in the cheese decreased with increasing curd firmness. The percentage of nitrogen recovered in the cheese was similar among the treatments. The amount of whey collected from the curd after milling increased as the coagulum firmness at cutting increased. Higher moisture content and lower pH of cheese made from the firmer curd at cutting contributed to softer, smoother-bodied cheeses, but the Cheddar flavor intensity was not affected.

Cheese↗
PubMed2001

Measurement of the size and orientation of human masseter and medial pterygoid muscles.

To gain a better understanding of biting and chewing performance, the size and orientation of the masseter and medial pterygoid muscles in living humans were studied. Twenty-seven young males having complete dentition, class I dental occlusion and normal muscle and jaw function were examined using magnetic resonance images of the head between the zygomatic arch and hyoid bone. The sections were parallel to the palatal plane, and the thickness was 3 mm without a gap. A computer software program (Medical Dental Image, MDI) was developed to identify and calculate the area of each cross section of the muscle, and the volume of the muscle was then estimated. The axis of the muscle was determined by connecting the centroids of the sections in the lower and upper 1/3 of the whole muscle. The effective muscle cross section area was then calculated by resectioning the muscle perpendicularly to the muscle axis. It was found that the mean masseter muscle volume was around 31 cm3, and that the mean medial pterygoid muscle volume was 11 cm3. Their mean effective cross section areas were around 6.2 cm2 and 3.5 cm2, respectively. The axis of the masseter muscle was more perpendicular to the palatal plane and parallel to the sagittal plane than was the medial pterygoid muscle. The results suggest that the use of magnetic resonance images (MRI) is an effective noninvasive measurement technique for determining the size and orientation of masseter and medial pterygoid muscles. This technique can be employed in future studies on human bite force evaluation and masticatory function.

Adolescent↗
PubMed2001

Increased toxicity of textile effluents by a chlorination process using sodium hypochlorite.

Chlorinated textile effluents were tested for their toxicity using different bioassays. These assays were the Microtox assay, daphnia (Daphnia similis) 48-hr survival test, medaka embryo 14-day and juvenile 96-hr survival tests, and tilapia (Oreochromis mossambicus) juvenile 96-hr survival test. By comparing the results of toxicity tests on water samples collected at the instream prior to the chlorination process and at the outlet of the wastewater treatment facility, we found that wastewater toxicity was obviously increased by chlorination using NaOCl as the oxidant, as evidenced by the different bioassays used. Because no significant difference was observed in water chemistry, such as pH, DO, and conductivity, the induced-toxicity may be partially attributable to residue chlorine or other chlorinated compounds generated by chlorination. Future studies are warranted to identify the cause of the increase in the textile wastewater toxicity.

Animals↗
PubMed2001

Predicting soil-water partition coefficients for Hg(II) from soil properties.

The metal adsorption characteristics for fifteen Taiwan soils by Hg(II), were evaluated using pH as the major variable. The soil samples were thoroughly characterized for their physical chemical properties and composition, particularly organic matter and metal oxides. The adsorption of Hg(II) increased with increasing pH between pH 2.5 and 5.5, whereas the adsorption significantly decreased above around pH 5.5. Below pH 5.5, greater adsorption was found for soils with a higher organic matter content at constant pH and metal concentration. To better understand the mechanism of adsorption, the experimental results for Hg (II) were tested in a partition coefficient model to relate the adsorption of the Hg(II) by the different soils with soil components: organic matter, iron oxide, aluminium oxide and manganese oxide. This model was not successful when applied to measurements at the differing natural soil pHs because of the importance of pH. At pH greater than 5.5 the model fails because of the complexation of Hg by the dissolved organic matter. However, partition coefficients obtained from experimental data were highly correlated with those calculated for a partition coefficient between mercury and organic matter alone at lower pH. Normalization of the partition coefficients, Kd, for the organic matter content of the soils, Kom, greatly improved the correlation between the partition coefficient and pH under pH 5.5 (R2 increased from 0.484 to 0.716). This suggests that the surficial adsorption sites are principally due to organic matter for pH less than 5.5. For the 24-hour equilibration period employed, diffusion of Hg through this superficial organic matter coating to underlying sorptive materials, including metal oxides, is not important in the partitioning of Hg. At pH above 5, a decrease of mercury adsorption with increasing solution pH was also found. This result may be explained in part by the complexation of mercury by soil dissolved organic matter whose concentration increased with increasing pH.

Adsorption↗
PubMed2001

Sonographic features of breast abscesses with emphasis on "hypoechoic rim" sign.

BACKGROUND: There are only limited reports on the ultrasound (US) features of breast abscess. The purpose of this paper is to review the US features of breast abscess with emphasis on "hypoechoic rim" sign which is more commonly seen in chronic abscess. METHODS: In a period of 10 years, 20,998 patients were referred for breast US examinations. Medical records identified 204 patients in whom breast abscess was diagnosed. All patients were examined using high-resolution real-time US scanners. The initial ultrasound reports and hard copy images were all carefully reviewed. The grading of the echogenicity of the abscess was classified from grade 0 to grade 5. The contours of the lesions were described as smooth, macrolobulated, microlobulated, irregular, zigzag, spiculate or indistinct. The wall thickness was measured to document the presence of "hypoechoic rim" which denoted a wall thickness greater than 2 mm. The associated findings and other acoustic phenomena related to the lesion were recorded. RESULTS: One hundred and thirty-six patients (136/204) having specific aspiration and/or biopsy/histopathological results were included in the study. All of the 136 patients showed abnormal US findings (100%). Most lesions showed grade 1 or grade 2 echogenicity (117, 86%). The contour of the abscess was usually smooth (42, 31%), macrolobulated (42, 31%), or irregular (22, 16%). A hypoechoic rim was noticed in 18 lesions (13%). Focal skin thickening was chiefly noticed in 91% of superficial abscesses (39/43) and 17% of intramammary abscesses (14/84). Diffuse skin thickening was exclusively evident in the breasts coexisting with mastitis. Hypoechoic interstitial streaks were not a common finding (7%), occurring in acute abscesses. The other findings included surrounding hypoechoic amorphous tissue (26%), posterior wall enhancement (71%), distal enhancement (60%) and lateral shadows (57%). CONCLUSIONS: US plays an important role in confirmation of the clinical diagnosis of breast abscess and aids significantly in the management of inflammatory breast diseases. Presence of the hypoechoic rim surrounding a fluid space or a central area of low-level echoes (i.e., grade 1 to grade 3) is indicative of a chronic abscess.

Abscess↗