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Biomedical subjects

C C Hu

Publications and source records attributed to C C Hu.

At least 19 recordsLinked to original sources
PubMed2005

Treatments of oil-refinery and steel-mill wastewaters by mesocosm constructed wetland systems.

In this study, two types of industrial wastewater, oil-refining and steel-milling, were selected for investigating their feasibility of treatment by mesocosm constructed wetland systems. The secondly treated effluents from the wastewater treatment plants were directly discharged into the systems controlled at different flow rates. Three wetland mesocosms were installed in the two industries: mesocosms A and B were in the oil refinery, and mesocosm C was in the steel mill. The substratum media used in wetland systems were sand (mesocosm A) and gravel (mesocosms B and C), while the vegetation types selected were reeds (mesocosms A and B) and mixed species of reeds and cattails (mesocosm C). The flow regimes were controlled as free water surface (FWS) and subsurface flow (SSF) for the sand- and gravel-beds, respectively. According to the experimental results, we found that the system treating oil-refining wastewater performed better than that treating steel-milling wastewater learned by comparing the removal efficiencies of COD, total N and total P. In addition, it was found that for oil-refining wastewater treatments, the SSF wetland system (mesocosm B) performed better than FWS (mesocosm A) wetland system when comparing both of their removal of pollutants and growth of vegetation. Besides, the effluents from these two industrial wetland treatment systems might be reclaimed and reused for boiler water, cooling, cleaning and miscellaneous purposes in industries. Further treatments are required if the constructed wetland effluents are thought about being reused for processing in industries.

Ecosystem↗
PubMed2002

Pig amelogenin gene expresses a unique exon 4.

The pig amelogenin gene was isolated from a Lambda genomic library, and a 6.3 kb SalI/XbaI restriction fragment, inclusive of exons 3 through 7, was subcloned into a plasmid vector. DNA sequencing revealed two putative exon 4 sequences. The derived amino acid sequence of exon 4a, KSGRWGARLTAFVSSVQ, had previously been identified in a 190-amino-acid amelogenin isoform by protein sequencing. Exon 4b encoded the peptide DLYLEAIRIDRTAF, which is homologous to exon 4-encoded segments reported for human, mouse, and rat. Oligonucleotides from both of these exons were used to amplify cDNA generated from developing teeth. Amplification products were analyzed by agarose gel electrophoresis, cloned, and characterized by DNA sequencing. Exon 4a was found in transcripts encoding amelogenin isoforms having 190 and 73 amino acids. Exon 4b was found only in apparent splicing intermediates that retained intron 3, but was not detected in any final mRNA transcripts. Pig amelogenin having apparent molecular mass of 23 kD were isolated from the enamel matrix and characterized by mass spectrometry. Two mass values, 18,512.5, and 18,571.2 Da, were measured that match the values predicted for the 162-amino-acid cleavage product of the 173-amino-acid amelogenin, and the 165-amino-acid cleavage product of the 190-amino-acid amelogenin, which includes 17 amino acids encoded by exon 4a. We conclude that the pig amelogenin gene expresses a unique exon 4 that is not homologous to, or evolved from, the exon 4 segment expressed in humans and rodents.

Alternative Splicing↗
PubMed2001

Synergistic effect of cadmium chloride and acetaldehyde on cytotoxicity and its prevention by quercetin and glycyrrhizin.

Cadmium chloride at concentrations of 10-50mM and acetaldehyde (AA) at 1-5mM showed synergistic toxic effects on V79 cells in vitro. Furthermore, synergistic effects of these chemicals were also observed in mutagenicities of the Hprt gene within certain dose ranges (cadmium chloride 5-10mM, and AA 1-2.5mM). Moreover, lipid peroxide formation, malondialdehyde (MDA) formation, detected by 2-thiobarbituric acid (TBA) reaction and the mitochondrial membrane potentials detected by rhodamine 123 uptake were significantly increased with the combined effect of cadmium and AA in V79. Thus, the cytotoxicity and genotoxicity displayed by combination of these chemicals can be considered to be associated with oxidative stress. Further, these effects were efficiently reduced by quercetin and less efficiently with glycyrrhizin.

Acetaldehyde↗
PubMed2001

Caspase activation in response to cytotoxic Rana catesbeiana ribonuclease in MCF-7 cells.

Rana catesbeiana ribonuclease (RC-RNase) and onconase were proven to own anti-tumor activity. While molecular determinants of onconase-induced cell death have become more explicit, the RC-RNase-induced death pathway remains presently unknown. Here we demonstrated that RC-RNase-induced molecular cascades in caspase-3-deficient MCF-7 cells did not include activation of initiation caspase-8 and -9. Cleavage timing suggested that procaspase-2 and -6 might be processed by active caspase-7 in MCF-7 cells. Caspase-7 was also responsible for cleavage of the poly(ADP-ribose) polymerase. Furthermore, we reported that overexpression of Bcl-X(L) could raise the survival rates of MCF-7 cells treated with RC-RNase and onconase.

Amphibian Proteins↗
PubMed2001

Synergistic cytotoxicity of Rana catesbeiana ribonuclease and IFN-gamma on hepatoma cells.

RC-RNase purified from Rana catesbeiana (bullfrog) oocytes is a pyrimidine-guanine sequence-specific ribonuclease. RC-RNase is derived from the RNase superfamily genes exerting distinct ribonucleolytic activity and possesses cytotoxicity to tumor cells, but rarely to primary cells. In this study, we utilized RC-RNase to function with antiproliferative cytokines. The combination with TNF-alpha or TNF-beta would not aggravate cell death. However, the combination with IFN-gamma could induce synergistic cytotoxicity verified by XTT assays toward three hepatoma cell lines bearing different differentiation stages. The distinct cytotoxicity from RC-RNase or RC-RNase/IFN-gamma on different hepatoma cells was correlated with the differentiation extent but not the proliferation rate of the cells. Despite the synergistic cytotoxicity and severe mitochondrial disruptions in the RC-RNase/IFN-gamma-treated cells, we scarcely detected any significant feature of apoptosis or necrosis by FACS analysis on annexin-V/propidium iodide staining. The mechanisms of cell death triggered by RC-RNase or RC-RNase/IFN-gamma require further investigation.

Amphibian Proteins↗
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

Calcium binding of enamel proteins and their derivatives with emphasis on the calcium-binding domain of porcine sheathlin.

Dental enamel is believed to form by the transfer of ions from solution, primarily calcium, phosphate, hydroxyl and carbonate, to the surface of solid-state mineral. Such precipitation phenomena can be controlled by regulating the degree of saturation of the solution with respect to the potential solid phases that can form. The concentration of free calcium is the factor that most affects the degree of saturation for calcium hydroxyapatite, and its buffering by calcium-binding proteins has been proposed as the mechanism that determines the enamel mineral structure. In this study, Stains-all staining was used to identify and isolate calcium-binding proteins from the enamel matrix, and determine their structures and association constants for calcium. Proteolytic cleavage fragments derived from the C-terminus of sheathlin, having apparent molecular weights of 13, 15, 27 and 29 kDa, were characterized by amino-terminal protein sequencing, amino acid analysis, and sugar, phosphate and sulphate determinations. Sheathlin C-terminal cleavage products were shown to have no N-linked glycosylations or phosphorylated amino acids, but Pro(350) was hydroxylated, and there was one sulphated O-linked glycosylation at Thr(386), containing galactose and N-acetylgalactosamine. The calcium-binding association constants for enamel proteins ranged from a high of 1.2 x 10(4) M(-1) to a low of 4.4x10(1) M(-1). The relative strengths of binding in order of decreasing affinity were: 13 and 15 kDa calcium-binding domain of sheathlin >27 and 29 kDa calcium-binding proteins >32 kDa enamelin >89 kDa enamelin >6.5 kDa, 25 kDa, 23 kDa, 20 kDa, 13 kDa, 5.3 kDa amelogenins. It is concluded that if enamel proteins have similar calcium-binding properties in vivo as have been measured in vitro, they would tend to buffer the free calcium ion concentration in enamel fluid.

Acetylgalactosamine↗
PubMed2001

The influence of inserting a Fuji pressure sensitive film between the tibiofemoral joint of knee prosthesis on actual contact characteristics.

OBJECTIVE: To investigate the influence of inserting a Fuji pressure sensitive film between the tibiofemoral joint of knee prosthesis on actual contact characteristics. DESIGN: A finite element analysis was used to investigate the alteration of contact characteristics of the tibiofemoral joint due to inserting a pressure sensitive film between the contacting surfaces. BACKGROUND: The discrepancy between actual contact behaviors of tibiofemoral joint of knee prosthesis and the measurement using Fuji pressure sensitive film was not discussed extensively. The change of direct contact circumstance of the tibiofemoral joint due to inserting a pressure sensitive film was not well reported. METHOD: A two-dimensional finite element model of the tibiofemoral joint of knee prosthesis in the sagittal plane was constructed. Four different radii of the femoral component were used to investigate the conformity effect. Two-layers of plane strain element were used to model the pressure sensitive film. The influence of inserting a pressure sensitive film on the actual contact characteristics was analyzed by comparing the results of the change in contact radius. RESULTS: Inserting a pressure sensitive film between contacting surfaces would disturb the original contact behaviors, especially in the lowest conformity design. The maximum difference of contact radius between the model simulating actual contact circumstance and the model with inserting a pressure sensitive film between contacting surface was 77% in the lowest conformity condition at the smallest load. CONCLUSIONS: This study proposes a quantitative analysis of contact characteristics in the tibiofemoral joint of knee prosthesis between the models with and without inserting a pressure sensitive film into the contact surface. The measurement of contact area in artificial tibiofemoral joints by using Fuji pressure sensitive film is always overestimated its true contact area by 14-77%. RELEVANCE: This study revealed the measurement of contact characteristics of artificial tibiofemoral joints by using Fuji pressure sensitive film which depends on not only the applied load, but also the conformity and material properties of the contact surface. Therefore, the information of the conformity and material properties of the contact surface should be provided as well as the applied load wherever a measurement of contact characteristics using Fuji pressure sensitive film is analyzed and interpreted.

Biomechanical Phenomena↗
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↗
PubMed2000

Differentiation status modulates transcription factor NF-kappaB activity in unstimulated human hepatocellular carcinoma cell lines.

We report herein a novel finding that under an unstimulated condition, a group of four human hepatocellular carcinoma (HCC) cell lines with varying degrees of differentiation, can spontaneously activate NF-KB. The propensity of activation coincided inversely with the differentiation status, with order being SK-Hep-1 > J5 > Hep3B > HepG2. Further studies indicate that this pattern of activation correlates excellently with the descending order of intracellular GSH/GSSG ratios as well as with the ascending order in the ability of these cells to generate hydrogen peroxide. Taken together, our data suggest that differentiation status may play a pivotal role in modulating intracellular thiol redox status and the extent of catalase expression, which may be crucial in the control of NF-kappaB activity in these HCC cells.

Carcinoma, Hepatocellular↗
PubMed2000

Induction of apoptosis in KB cells by pingyangmycin.

Pingyangmycin (PYM; Bleomycin A(5)), an antitumour antibiotic is currently used during anticancer therapy. Previous experiments demonstrated that the therapeutic efficiency of PYM for treatment of malignant tumours is considered to be related to its ability to cause DNA strand breaks in vitro. However, very little is known about the interaction of PYM with the target cells, and it is still unclear how PYM enters the cells. In this study, cell death induced by PYM was studied in a human squamous cell carcinoma cell line (KB cells). In order to determine if cell death occurred by necrosis (reproductive cell death) or apoptosis (programmed cell death), KB cells were exposed to different concentrations of PYM and evaluated by biochemical and morphological criteria. Our results indicate that KB cells displayed an arrest in the G(2)-M phase of the cell cycle and became enlarged and polynucleated before dying at the low concentrations of PYM. In contrast, when cells were exposed to high concentrations of PYM, morphological changes identical to those usually associated with apoptosis were observed as well as internucleosomal digestion of genomic DNA. In conclusion, we demonstrate that PYM is able to induce two distinct modes of cell death depending on the doses of PYM.

Antibiotics, Antineoplastic↗
PubMed2000

Cloning human enamelin cDNA, chromosomal localization, and analysis of expression during tooth development.

Enamelin is the largest protein in the enamel matrix of developing teeth. In the pig, enamelin is secreted as 186-kDa phosphorylated glycoprotein, which is rapidly processed by enamel proteinases into smaller cleavage products. During the secretory stage of enamel formation, enamelin is found among the crystallites in the rod and interrod enamel and comprises roughly 5% of total matrix protein. Although the function of enamelin is unknown, it is thought to participate in enamel crystal nucleation and extension, and the regulation of crystal habit. Here we report the results of enamelin in situ hybridization in a day 1 mouse developing incisor that shows that enamelin is expressed by ameloblasts, but not by odontoblasts or other cells in the dental pulp. The restricted pattern of enamelin expression makes the human enamelin gene a prime candidate in the etiology of amelogenesis imperfecta (AI), a genetic disease in which defects of enamel formation occur in the absence of non-dental symptoms. We have cloned and characterized a full-length human enamelin cDNA and determined by radiation hybrid mapping and fluorescent in situ hybridization (FISH) that the gene is located on chromosome 4q near the ameloblastin gene in a region previously linked to local hypoplastic AI in six families. These findings will facilitate the search for specific mutations in the enamelin gene in kindreds suffering from amelogenesis imperfecta.

Ameloblasts↗
PubMed1999

Molecular characterization of an atypical old world strain of Peanut stunt virus.

Northern blot analyses of RNAs from an Iranian strain of Peanut stunt virus (PSV-I Cucumovirus) using cloned cDNA probes to the genomic RNAs from two PSV strains, PSV-ER (subgroup I) and PSV-W (subgroup II), indicated that PSV-I RNA-3 is derived from a subgroup II strain. No hybridization signals, however, were detected with PSV-I RNAs 1 and 2 suggesting they are distinct from both subgroups I and II. Nucleotide (nt) sequence analysis of cloned cDNA fragments (1-1.5 kbp in size) representing PSV-I RNAs 1 and 2 showed that PSV-I is more closely related to subgroup II strains than to any other sequenced cucumovirus. The percent nt identity between RNA-1 sequences from PSV-I and PSV-ER or between PSV-I and PSV-W were 79.1% and 88.8%, respectively. The corresponding values for RNA-2 were 77.5% and 86.7%. Sequence comparison analyses of deduced amino acid sequence of cloned partial sequences of PSV-I RNAs 1 and 2 indicated that PSV-I 1a and 2a proteins are most closely related to those of subgroup II strains (93% identity). PSV-I supported the replication and encapsidation of PSV G-satellite RNA (G-satRNA), but not cucumber mosaic virus WL1-satRNA. PSV-I may be perceived as an Old World derivative of subgroup II strains, or it may represent a natural reassortment between a subgroup II (RNA-3) and an as yet uncharacterized subgroup of PSV strains (RNAs 1 and 2).

Amino Acid Sequence↗
PubMed1999

Complete nucleotide sequence of bean pod mottle virus RNA1: sequence comparisons and evolutionary relationships to other comoviruses.

The complete nucleotide sequence of bean pod mottle comovirus (BPMV) RNA 1 was determined. It is 5983 nucleotides long, excluding the poly(A) tail, and encodes a polyprotein of 1850 amino acid (aa) residues. Multiple alignments of the deduced aa sequence of BPMV polyprotein with those of cowpea mosaic virus (CPMV), red clover mottle virus (RCMV) and cowpea severe mosaic virus (CPSMV) indicated that BPMV RNA1 encodes the predicted set of five mature proteins: the equivalent of CPMV 32K protease cofactor, 58K putative helicase, VPg, 24K protease and 87K putative RNA-dependent RNA polymerase. Of the four proposed cleavage sites in BPMV RNA1 polyprotein, the one at the 32K/58K site (Q/A) is distinct for BPMV polyprotein and those at the 58K/VPg and VPg/24K junctions (Q/S and Q/M, respectively) are identical in all four comovirus polyproteins. Sequence comparison and phylogenetic analysis revealed that BPMV RNA1 is more closely related to CPSMV than to CPMV or to RCMV.

Amino Acid Sequence↗
PubMed1999

Characterization of recombinant pig enamelysin activity and cleavage of recombinant pig and mouse amelogenins.

Enamelysin (MMP-20) is a tooth-specific matrix metalloproteinase that is initially expressed by ameloblasts and odontoblasts immediately prior to the onset of dentin mineralization, and continues to be expressed throughout the secretory stage of amelogenesis. During the secretory stage, enamel proteins are secreted and rapidly cleaved into a large number of relatively stable cleavage products. Multiple proteinases are present in the developing enamel matrix, and the precise role of enamelysin in the processing of enamel proteins is unknown. We have expressed, activated, and purified the catalytic domain of recombinant pig enamelysin, and expressed a recombinant form of the major secreted pig amelogenin rP172. These proteins were incubated together, and the digestion products were analyzed by SDS-PAGE and mass spectrometric analyses. We assigned amelogenin cleavage products by selecting among the possible polypeptides having a mass within 2 Daltons of the measured values. The polypeptides identified included the intact protein (amino acids 2-173), as well as 2-148, 2-136, 2-107, 2-105, 2-63, 2-45, 46-148, 46-147, 46-107, 46-105, 64-148, 64-147, and 64-136. These fragments of rP172 include virtually all of the major amelogenin cleavage products observed in vivo. We propose that enamelysin is the predominant proteinase that processes enamel proteins during the secretory phase of amelogenesis.

Amelogenesis↗
PubMed1998

Reparative dentin formation in rat molars after direct pulp capping with growth factors.

Growth factors involved in normal wound healing may promote tissue repair when applied as a direct pulp capping medication. A minimal pulp exposure was made in rat molars, a pulp capping medication was placed, and the cavity was sealed. Epidermal growth factor, basic fibroblast growth factor, insulin-like growth factor II, platelet-derived growth factor-BB, and transforming growth factor-beta 1 (TGF-beta 1)--each absorbed onto a sterile collagen membrane (BioMend; Calcitek, Carlsbad, CA)--were used separately as pulpal medicaments. Dycal, unimpregnated collagen membrane, and no medication were used as controls. Eight samples from each treatment regimen were collected 2 and 3 weeks after surgery. Pulpal soft and hard tissue responses were graded. Data were analyzed by one-way ANOVA and Tukey-Kramer tests. No significant differences were detected after 2 wk. Pulp treated with TGF-beta 1 showed significantly improved soft and hard tissue healing at week 3, compared with the procedure control. We conclude that TGF-beta 1 as a pulp-capping medication enhances reparative dentin formation in rat molars.

Analysis of Variance↗