Biomedical subjects

Y C Chang

Publications and source records attributed to Y C Chang.

At least 37 records · Page 2Linked to original sources

PubMed2001

Working memory of school-aged children with a history of febrile convulsions: a population study.

OBJECTIVE: A prospective, population-based, case-control study was performed to ascertain whether febrile convulsion (FC) in early childhood is associated with specific working memory characteristics in school age. METHODS: From a population survey of 4,340 live-birth newborns in Tainan City, Taiwan, 103 children with confirmed FC by age 3 years were followed-up until they were at least 6 years old. Three analogous searching tasks dissociating the mnemonic and executive aspects of performances were administered to 87 of these school-aged children and to 87 randomly selected age-matched control subjects to assess the learning, spatial, and sequential working memory. RESULTS: The FC group performed significantly and consistently better than control subjects on all but one working memory measure, jumping errors. Multivariate analysis using linear regression revealed that the onset of FC before age 1 year was the only significant risk factor for deficits in mnemonic function. Prior neurodevelopmental delay was the only significant risk factor for deficits in executive function. Factors such as socioeconomic status, family predisposition for seizures, complex FC, recurrent FC, and subsequent unprovoked seizures were not risk factors for working memory deficits. CONCLUSION: The authors found that school-aged children with a history of FC demonstrated significantly better mnemonic capacity, more flexible mental processing, and higher impulsivity than their age-matched control subjects. The underlying mechanism for the facilitated working memory function in children with a history of FC needs further delineation.

Child↗

PubMed2001

Pentaketide melanin biosynthesis in Aspergillus fumigatus requires chain-length shortening of a heptaketide precursor.

Chain lengths and cyclization patterns of microbial polyketides are generally determined by polyketide synthases alone. Fungal polyketide melanins are often derived from a pentaketide 1,8-dihydroxynaphthalene, and pentaketide synthases are used for synthesis of the upstream pentaketide precursor, 1,3,6,8-tetrahydroxynaphthalene (1,3,6,8-THN). However, Aspergillus fumigatus, a human fungal pathogen, uses a heptaketide synthase (Alb1p) to synthesize its conidial pigment through a pentaketide pathway similar to that which produces 1,8-dihydroxynaphthalene-melanin. In this study we demonstrate that a novel protein, Ayg1p, is involved in the formation of 1,3,6,8-THN by chain-length shortening of a heptaketide precursor in A. fumigatus. Deletion of the ayg1 gene prevented the accumulation of 1,3,6,8-THN suggesting the involvement of ayg1 in 1,3,6,8-THN production. Genetic analyses of double-gene deletants suggested that Ayg1p catalyzes a novel biosynthetic step downstream of Alb1p and upstream of Arp2p (1,3,6,8-THN reductase). Further genetic and biochemical analyses of the reconstituted strains carrying alb1, ayg1, or alb1 + ayg1 indicated that Ayg1p is essential for synthesis of 1,3,6,8-THN in addition to Alb1p. Cell-free enzyme assays, using the crude Ayg1p protein extract, revealed that Ayg1p enzymatically shortened the heptaketide product of Alb1p to 1,3,6,8-THN. Thus, the protein Ayg1p facilitates the participation of a heptaketide synthase in a pentaketide pathway via a novel polyketide-shortening mechanism in A. fumigatus.

Alcohol Oxidoreductases↗

PubMed2001

Condensation by DNA looping facilitates transfer of large DNA molecules into mammalian cells.

Experimental studies of complete mammalian genes and other genetic domains are impeded by the difficulty of introducing large DNA molecules into cells in culture. Previously we have shown that GST-Z2, a protein that contains three zinc fingers and a proline-rich multimerization domain from the polydactyl zinc finger protein RIP60 fused to glutathione S-transferase (GST), mediates DNA binding and looping in vitro. Atomic force microscopy showed that GST-Z2 is able to condense 130-150 kb bacterial artificial chromosomes (BACs) into protein-DNA complexes containing multiple DNA loops. Condensation of the DNA loops onto the Z2 protein-BAC DNA core complexes with cationic lipid resulted in particles that were readily transferred into multiple cell types in culture. Transfer of total genomic linear DNA containing amplified DHFR genes into DHFR(-) cells by GST-Z2 resulted in a 10-fold higher transformation rate than calcium phosphate co-precipitation. Chinese hamster ovarian cells transfected with a BAC containing the human TP53 gene locus expressed p53, showing native promoter elements are active after GST-Z2-mediated gene transfer. Because DNA condensation by GST-Z2 does not require the introduction of specific recognition sequences into the DNA substrate, condensation by the Z2 domain of RIP60 may be used in conjunction with a variety of other agents to provide a flexible and efficient non-viral platform for the delivery of large genes into mammalian cells.

Animals↗

PubMed2001

The second STE12 homologue of Cryptococcus neoformans is MATa-specific and plays an important role in virulence.

Cryptococcus neoformans STE12alpha, a homologue of Saccharomyces cerevisiae STE12, exists only in MATalpha strains. We identified another STE12 homologue, STE12a, which is MATa specific. As in the case with Deltaste12alpha, the mating efficiency for Deltaste12a was reduced significantly. The Deltaste12a strains surprisingly still mated with Deltaste12alpha strains. In MATalpha strains, STE12a functionally complemented STE12alpha for mating efficacy, haploid fruiting, and regulation of capsule size in the mouse brain. Furthermore, when STE12a was replaced with two copies of STE12alpha, the resulting MATa strain produced hyphae on filament agar. STE12a regulates mRNA levels of several genes that are important for virulence including CNLAC1 and CAP genes. STE12a also modulates enzyme activities of phospholipase and superoxide dismutase. Importantly, deletion of STE12a markedly reduced the virulence in mice, as is the case with STE12alpha. Brain smears of mice infected with the Deltaste12a strain showed yeast cells with a considerable reduction in capsule size compared with those infected with STE12a strains. When the disrupted locus of ste12a was replaced with a wild-type STE12a gene, both in vivo and in vitro mutant phenotypes were reversed. These results suggest that STE12a and STE12alpha have similar functions, and that the mating type of the cells influences the alleles to exert their biological effects. C. neoformans, thus, is the first fungal species that contains a mating-type-specific STE12 homologue in each mating type. Our results demonstrate that mating-type-specific genes are not only important for saprobic reproduction but also play an important role for survival of the organism in host tissue.

Base Sequence↗

PubMed2001

Dentatorubropallidoluysian atrophy in Chinese.

BACKGROUND: Dentatorubropallidoluysian atrophy (DRPLA) is a rare, autosomal dominant neurodegenerative disease characterized by a range of clinical manifestations, including cerebellar ataxia, epilepsy, myoclonus, choreoathetosis, and dementia. Outside the Japanese population, the prevalence is extremely low worldwide. The reason for different ethnic prevalences of DRPLA is unclear. A previous assumption was that large normal alleles contribute to generation of expanded alleles and the relative frequencies of DRPLA. OBJECTIVES: To describe the clinical, radiological, and genetic features of the first reported Chinese family with DRPLA, to our knowledge, and to compare the size distribution of normal alleles at the DRPLA locus in healthy Chinese individuals with that of other ethnic groups. PATIENTS AND METHODS: Of 80 Chinese kindreds with autosomally dominant spinocerebellar ataxias, 1 pedigree with 2 affected patients was found by polymerase chain reaction to carry the characteristic DRPLA mutation. The allele frequencies of different CAG repeat lengths at the DRPLA locus in 225 healthy Chinese individuals were also analyzed and compared with Japanese, white, and African American distributions. RESULTS: The clinical presentations of the 2 Chinese patients affected with DRPLA are similar to those described in Japanese patients, except that the affected father exhibited myoclonus but not chorea. Although the normal DRPLA allele size is distributed similarly in Chinese and Japanese populations, DRPLA in Chinese individuals is rare. Thus far, to our knowledge, only 1 intermediate-sized allele containing more than 30 CAG repeats has been reported among healthy Chinese individuals, in contrast to 3 among Japanese populations. CONCLUSION: The ethnic prevalence of DRPLA seems to be correlated with the prevalence of intermediate-sized alleles in individual populations.

Adult↗

PubMed2001

Value of chest sonography in the diagnosis and management of acute chest disease.

PURPOSE: The aim of this study was to investigate the value of chest sonography in the diagnosis and management of patients with chest radiograph opacities in an emergency department. METHODS: Seventy-eight patients with acute chest complaints whose chest radiographs showed opacities underwent chest sonography. The initial diagnosis (based on clinical manifestations and the chest radiograph), the sonographic diagnosis (before any invasive procedures), and the final diagnosis were compared. The impact of chest sonography on the management of patients with chest opacities was also analyzed. RESULTS: The initial diagnosis was in concordance with the final diagnosis in 60 (77%) of the 78 patients, while the sonographic diagnosis was in concordance with the final diagnosis in 75 (96%) of the patients. Chest sonography therefore significantly increased the rate of correct diagnoses from 77% (95% confidence interval, 67-87%) to 96% (95% confidence interval, 92-100%; p < 0.0001). Sonography provided new information in 52 patients (67%): a different diagnosis from the initial diagnosis in 18 patients and additional diagnostic information in 34 patients. New information gained from sonography affected the management of 35 patients. Sonography also provided help in guiding 42 (70%) of 60 invasive diagnostic procedures and 22 (73%) of 30 invasive therapeutic procedures for which chest radiography and physical examination had failed to or were unsuitable to provide guidance. Overall, sonography assisted in the management of 64 (82%) of 78 patients. Sonography was of no benefit in 14 patients (18%). CONCLUSIONS: We conclude that chest sonography can complement chest radiography and is of value in the diagnosis and management of emergency department patients with acute chest diseases presenting as opacities on chest radiographs.

Acute Disease↗

PubMed2001

Cytotoxicity and immunogenicity of SACCHACHITIN and its mechanism of action on skin wound healing.

SACCHACHITIN membrane, a weavable skin substitute made from the residual fruiting body of Ganoderma tsugae, has been demonstrated to promote skin wound healing. Prior to its clinical application, it is critical to learn more about any possible cytotoxicity, immunogenicity, or allergy response, and at least some of its mechanism(s) of action(s). In the present studies, it has been found that SACCHACHITIN suspension at less than 0.05% shows no cytotoxicity to the primary culture of rat fibroblasts. However, at higher concentrations (> or = 0.1%), it does reduce the growth of fibroblasts, based on MTT assays. This might be caused by positive charges on chitin molecules that are too strong, and may be harmful to the cell membrane. SACCHACHITIN showed no immunogenicity after it was inoculated into rats three times; however, the unmodified, purified rabbit type I and type II collagens did. Subcutaneous injection of SACCHACHITIN suspension into rats showed no gross allergic responses on skin. Nevertheless, it did cause local acute inflammation, as observed by histological investigation. This is similar to what occurred in the wound site covered with SACCHACHITIN membrane. The chemotactic effect of SACCHACHITIN was exhibited in both intact and wounded skin tissues. This may be one of the initial beneficial effects of SACCHACHITIN membrane to wound healing. The rapid acute inflammatory process was followed by the appearance of angiogenesis and granulation tissue formation, which occurred earlier than it normally would. Coverage of the wound area with SACCHACHITIN membrane also induced an earlier formation of scar tissue to replace the granulation tissue. A 1.5 x 1.5 cm(2) wound area covered by SACCHACHITIN completely healed by 21 days, while that covered with cotton gauze did not. Therefore, SACCHACHITIN is a safe biomaterial for use as a wound dressing for skin healing. Its promoting action for wound healing might be due to its chemotactic effect for inflammatory cells. This, in turn, may facilitate subsequent angiogenesis, granulation tissue formation, and faster new tissue formation, leading to faster wound healing.

Animals↗

PubMed2001

Proteome alterations in human hepatoma cells transfected with antisense epidermal growth factor receptor sequence.

The epidermal growth factor (EGF) is a member of the growth factor superfamily that can stimulate the proliferation of many types of cells. Overexpression of EGF receptor (EGFR) was observed in many types of cancer cells. Anti-EGFR antibodies or antisense nucleic acid sequences of EGFR can suppress the growth of hepatoma cells. In order to further investigate the proteome alterations associated with malignant growth of the human hepatoma cells and the influence of EGFR signal pathway on the cellular proteome, we have comparatively analyzed the proteomes of human hepatoma cells transfected with antisense EGFR sequence (cell strain JX-1) and its control cells (cell strain JX-0) by two-dimensional (2-D) gel electrophoresis and mass spectrometry. Image analysis of silver-stained 2-D gels revealed that 40 protein spots showed significant expression changes in JX-1 cells compared to JX-0 cells. Three of them, including the tumor suppressor protein maspin, changed with tendency to the normal levels. Two protein spots were identified as HSP27 in the same gel, and one of them had a reduced level in JX-1 cells. The apparent alterations of HSP27 in expression level might be the results from their differential chemical modifications, suggesting the effect of dynamic post-translational modifications of proteins on the growth of hepatoma cells. Other proteins such as glutathione peroxidase (GPX-1) and 14-3-3-sigma also exhibited altered expression in JX-1 cells, and their functional implications are discussed.

Amino Acid Sequence↗

PubMed2001

Differences in 99mTc-HMPAO brain SPET perfusion imaging between Tourette's syndrome and chronic tic disorder in children.

Early differential diagnosis between Tourette's syndrome and chronic tic disorder is difficult but important because both the outcome and the treatment of these two childhood-onset diseases are distinct. We assessed the sensitivity and specificity of brain single-photon emission tomography (SPET) perfusion imaging in distinguishing the two diseases, and characterized their different cerebral perfusion patterns. Twenty-seven children with Tourette's syndrome and 11 with chronic tic disorder (mean age 9.5 and 8.6 years, respectively) underwent brain SPET with technetium-99m hexamethylpropylene amine oxime (HMPAO). Visual interpretation and semiquantitative analysis of SPET images were performed. On visual interpretation, 22 of 27 (82%) of the Tourette's syndrome group had lesions characterized by decreased perfusion. The left hemisphere was more frequently involved. None of the children with chronic tic disorder had a visible abnormality. Semi-quantitative analysis showed that, compared with children with chronic tic disorder, children with Tourette's syndrome had significantly lower perfusion in the left lateral temporal area and asymmetric perfusion in the dorsolateral frontal, lateral and medial temporal areas. In conclusion, using the visual approach, brain SPET perfusion imaging is sensitive and specific in differentiating Tourette's syndrome and chronic tic disorder. The perfusion difference between the two groups, demonstrated by semi-quantitative analysis, may be related more to the co-morbidity in Tourette's syndrome than to tics per se.

Adolescent↗

PubMed2001

Quantitative pathology of cutaneous nerve terminal degeneration in the human skin.

Pathological diagnosis of neuropathy has traditionally depended on ultrastructural examinations of nerve biopsy specimens, particularly for sensory neuropathies affecting unmyelinated and small-myelinated nociceptive nerves. These sensory nerves terminate in the epidermis of the skin, and the pathology of neuropathy usually begins from nerve terminals. We investigated the feasibility of diagnosing small-fiber sensory neuropathy by evaluating cutaneous innervation. Skin biopsy specimens of 3-mm in diameter were obtained from the distal leg and the distal forearm of 55 healthy controls and 35 patients with sensory neuropathy. In the healthy controls, conventional intraepidermal nerve fiber densities (IENF densities) as measured using the image analysis system in the distal forearm and in the distal leg were correlated (r=0.55, P<0.0001), with significantly higher values in the distal forearm than in the distal leg (17.07+/-6.51 vs 12.92+/-5.33 fibers/mm, P<0.001). Compared to IENF densities of healthy controls, these values of neuropathic patients were significantly reduced in the distal forearm (5.82+/-6.50 fibers/mm, P<0.01) and in the distal leg (2.40+/-2.30, P<0.001). We further explored the possibility of quantifying skin innervation by counting "ocular intraepidermal nerve fiber density" (ocular nerve fiber density) with no aid of an image analysis system. This was based on the fact that the epidermal length on specifically defined sections was very close to the predicted epidermal length of 3 mm, the diameter of skin punches (P=0.14). Ocular nerve fiber densities were significantly correlated with IENF densities as measured by the image analysis system (r=0.99, P<0.0001). Dermal nerve fibers of neuropathic patients either disappeared or became degenerated. These findings were consistent with the notion of early terminal degeneration in neuropathy, and will facilitate quantitative interpretation of epidermal innervation in human neuropathy.

Adult↗

PubMed2001

Antimicrobial activity of four root canal sealers against endodontic pathogens.

The antibacterial effects of various types of widely used endodontic sealers have not been compared systematically on facultative or obligate anaerobic endodontic pathogens. The aim of this study was to evaluate the antimicrobial properties of four commonly used endodontic sealers: two epoxy-resin-based sealers (AH26, AH plus), one zinc-oxide eugenol-based sealer (N2), and one calcium hydroxide-based sealer (Sealapex). The testing microbes were four facultative anaerobic species (Streptococcus mutans, Streptococcus sanguis, Escherichia coli, and Staphylococcus aureus) and four obligate anaerobic species (Porphyromonas gingivalis, Porphyromonas endodontalis, Fusobacterium nucleatum, and Prevotella intermedia). The freshly mixed sealers were placed into the prepared wells of agar plates inoculated with the test microorganisms. After varying periods of incubation (2 days for facultative anaerobic species and 7 days for obligate anaerobic species), the zones of growth inhibition were observed and measured. All the sealers were distinctly different from each other in their antimicrobial activity. The sealers showed different inhibitory effects depending on the types and bacterial strains. N2 containing formaldehyde and eugenol proved to be the most effective against the microorganisms. The extreme antimicrobial potency of this root canal sealer must be weighted against its pronounced tissue toxic effect.

Analysis of Variance↗

PubMed2001

Cytotoxicity and arecoline mechanisms in human gingival fibroblasts in vitro.

Betel nut chewing, like cigarette smoking, is a popular oral habit which impinges on the daily lives of a population of approximately 200 million. People who chew betel nuts have a higher prevalence of periodontal diseases than those who do not. Many of the undesirable effects of betel nuts have been attributed to arecoline, a major component of the particular alkaloid in betel nuts. In this in vitro study, we have focused on the effects of arecoline and the role it could play in periodontal breakdown via its direct effects on human gingival fibroblasts. Human gingival fibroblasts were derived from three healthy individuals undergoing crown-lengthening procedures. We found that arecoline is cytotoxic to human gingival fibroblasts at a concentration higher than 50 micrograms/ml by depleting intracellular thiols and inhibiting mitochondrial activity (P < 0.05). In addition, the cells displayed a marked arrest at G2/M phase in a dose-dependent manner. Repeated and long-term exposure to arecoline could impair the gingival fibroblast functions. As they are cytotoxic, the use of betel nut products in conjunction with periodontal therapy may interfere with optimal healing and/or lead to further periodontal breakdown.

Adult↗

PubMed2001

Easier hepatic resections with a straight needle.

BACKGROUND: A stainless-sheathed, straight needle with a hook near the top of the inner needle was designed to facilitate hepatic resections. METHODS: First, using this needle, two rows of interlocking mattress sutures were made along the division line; then, hepatic transection was performed between these rows by electrocautery or forceps. RESULTS: Since 1997, we have performed this kind of hepatic resections in 43 cases, including 9 right lobectomies, 5 bisegmentectomies, 7 segmentectomies, 4 subsegmentectomies, 2 partial hepatectomies, 15 left lateral segmentectomies, and 1 hepatorrhaphy. In most cases, intraoperative hemorrhage was minimal. Neither specified inflow nor backflow control procedures were needed. CONCLUSION: Use of this needle may reduce the difficulty of the technique and blood loss for right hepatic lobectomy, left lateral segmentectomy, and some segmental or partial hepatectomy procedures.

Blood Loss, Surgical↗

PubMed2001

In vitro dehalogenation of tetrachloroethylene (PCE) by cell-free extracts of Clostridium bifermentans DPH-1.

Cell-free extracts of Clostridium bifermentans DPH-1 catalyzed tetrachloroethylene (PCE) dechlorination. PCE degradation was stimulated by addition of a variety of electron donors. Ethanol (0.61 mM) was the most effective electron donor for PCE dechlorination. Maximum activity was recorded at 30 degrees C and pH 7.5. Addition of NADH as a cofactor stimulated enzymatic activity but the activity was not stimulated by addition of metal ions. When the cell-free enzyme extract was incubated in the presence of titanium citrate as a reducing agent, the dehalogenase was rapidly inactivated by propyl iodide (0.5 mM). The activity of propyliodide-reacted enzyme was restored by illumination with a 250 W lamp. The dehalogenase activity was also inhibited by cyanide. The substrate spectrum of activity included trichloroethylene (TCE), cis-1,2-dichloroethylene (cDCE), trans-dichloroethylene, 1,1-dichloroethylene, 1,2-dichloroethane, and 1,1,2-trichloroethane. The highest rate of degradation of the chlorinated aliphatic compounds was achieved with PCE, and PCE was principally degraded via TCE to cDCE. Results indicate that the dehalogenase could play a vital role in the breakdown of PCE as well as a variety of other chlorinated aliphatic compounds.

Biodegradation, Environmental↗

PubMed2001

Isolation and characterization of antioxidant compounds from Aspergillus candidus broth filtrate.

The objectives of this study were to isolate the antioxidative components in the broth filtrate of Aspergillus candidus (CCRC 31543), to characterize their antioxidative properties, and to evaluate their safety. Three major compounds were isolated and identified as 3,3' '-dihydroxyterphenyllin, 3-hydroxyterphenyllin, and candidusin B. In the linoleic acid peroxidation system, the inhibition of peroxidation in these three compounds was greater than 95% and was significantly higher than that of alpha-tocopherol but equal to that of BHA at 12.5-200 microg/mL. As measured using the Rancimat method in lard, 3,3' '-di-OH-terphenyllin exhibited a protection factor value of 7.82, which was substantially higher than those of BHA (5.58) and alpha-tocopherol (4.29) at 200 microg/mL. 3,3' '-di-OH-terphenyllin and 3-OH-terphenyllin also exhibited marked scavenging effects on the alpha,alpha-diphenyl-beta-picrylhydrazyl radicals (94.7 and 96.0%, respectively), which were similar to those of BHA and alpha-tocopherol. Safety studies showed that these three compounds were neither cyto- nor geno-toxic toward human intestine 407 (INT 407) cells, nor mutagenic toward Salmonella typhimurium TA98 and TA100.

Antioxidants↗

PubMed2001

Adverse effects of arecoline and nicotine on human periodontal ligament fibroblasts in vitro.

BACKGROUND, AIMS: The habit of betel nut chewing impinges on the daily lives of approximately 200 million people. Betel quid chewers have a higher prevalence of periodontal diseases than non-chewers. This study examined the pathobiological effects of arecoline, a major component of the betel nut alkaloids, on human periodontal ligament fibroblasts (PDLF) in vitro. METHOD: Cell viability, proliferation, protein synthesis, and cellular thiol levels were used to investigate the effects of human PDLF exposed to arecoline levels of 0 to 200 microg/ml. In addition, nicotine was added to test how it modulated the effects of arecoline. RESULTS: Arecoline significantly inhibited cell proliferation in a dose-dependent manner. At concentrations of 10 and 30 microg/ml, arecoline suppressed the growth of PDLF by 20% and 50% (p < 0.05), respectively. Arecoline also decreased protein synthesis in a dose-dependent manner during a 24-h culture period. A 100 microg/ ml concentration level of arecoline significantly inhibited protein synthesis to only 50% of that in the untreated control (p < 0.05). Moreover, arecoline significantly depleted intracellular thiols in a dose-dependent manner. At concentrations of 25 microg/ml and 100 microg/ml, arecoline depleted about 18% and 56% of thiols (p < 0.05), respectively. This suggests that arecoline itself might augment the destruction of periodontium associated with betel nut use. Furthermore, the addition of nicotine acted with a synergistic effect on the arecoline-induced cytotoxicity. At a concentration of 60 microg/ml, arecoline suppressed the growth of PDLF by about 33% and 5 mM nicotine enhanced the arecoline-induced cytotoxic response to cause about 66% cell death. CONCLUSION: During thiol depletion, arecoline may render human PDLF more vulnerable to reactive agents within cigarettes. Taken together, people who combine habits of betel nut chewing with cigarette smoking could be more susceptible to periodontium damage than betel nut chewing alone.

Areca↗

PubMed2001

Synergistic effects of nicotine on arecoline-induced cytotoxicity in human buccal mucosal fibroblasts.

Areca quid chewing has been linked to oral submucous fibrosis and oral cancer. Arecoline, a major areca nut alkaloid, is considered to be the most important etiologic factor in the areca nut. In order to elucidate the pathobiological effects of arecoline, cytotoxicity assays, cellular glutathione S-transferase (GST) activity and lipid peroxidation assay were employed to investigate cultured human buccal mucosal fibroblasts. To date, there is a large proportion of areca quid chewers who are also smokers. Furthermore, nicotine, the major product of cigarette smoking, was added to test how it modulated the cytotoxicity of arecoline. At a concentration higher than 50 microg/ml, arecoline was shown to be cytotoxic to human buccal fibroblasts in a dose-dependent manner by the alamar blue dye colorimetric assay (P<0.05). In addition, arecoline significantly decreased GST activity in a dose-dependent manner (P<0.05). At concentrations of 100 microg/ml and 400 microg/ml, arecoline reduced GST activity about 21% and 46%, respectively, during a 24 h incubation period. However, arecoline at any test dose did not increase lipid peroxidation in the present human buccal fibroblast test system. The addition of extracellular nicotine acted synergistically on the arecoline-induced cytotoxicity. Arecoline at a concentration of 50 microg/ml caused about 30% of cell death over the 24 h incubation period. However, 2.5 mM nicotine enhanced the cytotoxic response and caused about 50% of cell death on 50 microg/ml arecoline-induced cytotoxicity. Taken together, arecoline may render human buccal mucosal fibroblasts more vulnerable to other reactive agents in cigarettes via GST reduction. The compounds of tobacco products may act synergistically in the pathogenesis of oral mucosal lesions in areca quid chewers. The data presented here may partly explain why patients who combined the habits of areca quid chewing and cigarette smoking are at greater risk of contracting oral cancer.

Analysis of Variance↗

PubMed2001

Identifying an interfering factor on chemical oxygen demand (COD) determination in piggery wastewater and eliminating the factor by an indigenous Pseudomonas stutzeri strain.

AIMS: This study attempted to demonstrate nitrite interference on chemical oxygen demand (COD) determination in piggery wastewater, and the capability of aerobic denitrification of the SU2 strain which is capable of promoting the efficiency of nitrogen and COD removal from piggery wastewater. METHODS AND RESULTS: This study was performed in a 17-litre reactor with a 30% packing ratio, with a ratio of immobilized SU2 cells to sludge of 100:1. The ratio of aeration to nonaeration was 4 : 1.5. Removal efficiency of COD was 86.8%. Removal efficiency of BOD and SS was higher than 90%, and removal efficiency of NH4+-N and TKN was almost 100%. CONCLUSIONS: NO2- -N interference is significant when its concentration in piggery wastewater exceeds 100 mg l-1. COD in piggery wastewater can be indirectly reduced following nitrite reduction by SU2 strain. SIGNIFICANCE AND IMPACT OF THE STUDY: Utilizing immobilized SU2 cells in coordination with an SBR system simultaneously reduces nitrite and COD concentrations.

Aerobiosis↗