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Biomedical subjects

C H Cheng

Publications and source records attributed to C H Cheng.

At least 55 records · Page 3Linked to original sources
PubMed2000

Inhibition of xanthine oxidase by liquiritigenin and isoliquiritigenin isolated from Sinofranchetia chinensis.

The methanol extract of the stem of Sinofranchetia inhibited the activity of xanthine oxidase in vitro. Bioassay-guided purification led to the isolation ofliquiritigenin and isoliquiritigenin as the main xanthine oxidase inhibitors. This inhibition of enzyme activity was found to be dose dependent, with an IC50 value of approximately 49.3 microM for liquiritigenin and 55.8 microM for isoliquiritigenin. Lineweaver-Burk transformation of the inhibition data indicated that the inhibition was of a mixed type for both liquiritigenin and isoliquiritigenin. For liquiritigenin, the Ki and K(I) were determined to be 14.0 microM and 151.6 microM, respectively. For isoliquiritigenin, the Ki and K(I) were determined to be 17.4 microM and 81.9 microM, respectively. These results suggest that these natural products could be used to treat conditions where the inhibition of xanthine oxidase is warranted.

Animals↗
PubMed2000

TNP-470 inhibits intraabdominal adhesion formation.

BACKGROUND/PURPOSE: Angiogenesis plays an integral role in wound healing and tissue remodeling. The authors hypothesized that inhibition of angiogenesis would reduce intraabdominal adhesion formation. METHODS: In 98 C57BL6/J mice, a 2-cm midline laparotomy was performed and a 5 mm2 SILASTIC (Dow Corning, Midland, MI) patch fixed to the right side of the peritoneum. Mice were injected with normal saline (n = 54) or TNP-470, an inhibitor of angiogenesis (n = 44; 30 mg/kg every other day over 6 days before surgery until 10 days after surgery). Animals were killed on postoperative days 10, 15, 35, and 55. Adhesions to the SILASTIC (Dow Corning) patch were scored based on their extent, type, and tenacity. Angiogenesis was quantified digitally as the area of vascularized peritoneum over the patch. RESULTS: At day 10, when TNP-470 was stopped, the percentage of vascularized peritoneum over the patch was less in treatment animals than in controls (P = .004). At day 35, the patch in treatment animals was completely covered by vascularized peritoneum, similar to controls. Adhesions in TNP-470 animals were reduced at day 10 compared with controls (P<.05) and remained reduced off treatment at day 55. CONCLUSIONS: Angiogenesis appears to play an important role in the development of intraabdominal adhesions, because the extent of early neovascularization correlates with adhesion formation. Perioperative treatment with TNP-470, a potent endothelial cell inhibitor, reduced vessel ingrowth over the patch and was associated with a sustained reduction in adhesion formation.

Abdomen↗
PubMed2000

Molecular cloning and expression studies of a prolactin receptor in goldfish (Carassius auratus).

A full-length cDNA clone, of a size of 4.6 kb, for the goldfish prolactin receptor has been isolated. This cDNA clone encodes a protein of 600 amino acids homologous to prolactin receptors of other species. A Kyte-Doolittle hydropathy analysis of the receptor indicates that the translated protein consists of a signal peptide of 22 amino acids, an extracellular domain of 228 amino acids, a single transmembrane domain of 24 amino acids, and an intracellular domain of 346 amino acids. Several characteristic landmarks of prolactin receptor could be identified in this clone. These include the four conserved cysteine residues and the WS motif within the extracellular domain, and the box 1 and box 2 regions of the intracellular domain. Among all the prolactin receptor sequences known to date, this clone bears the closest resemblance to the tilapia prolactin receptor, although homology between these two fish prolactin receptors is rather low. There are only 57.4% of nucleotide and 48.3% of amino acid sequence identities between these two fish receptors. This receptor cDNA was transfected into CHO-K1 cells for functional analysis. RT-PCR analysis with a pair of gene specific primers indicate that the receptor was transcribed in the transfected cells. Using a cell proliferation assay based on the reduction of the tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, the receptor transfected CHO-K1 cells can be stimulated to proliferate upon the addition of ovine prolactin in the culture medium. The tissue distribution of the prolactin receptor in goldfish was studied by RT-PCR/Southern analysis and by Northern analysis. The results indicated that the receptor is expressed mostly in the kidney, the gill and the intestine of goldfish, corroborating with the osmoregulatory role of prolactin in fish. In addition, an appreciable level of the receptor is also found in the brain and gonads of goldfish. Northern analysis showed that there are two transcript sizes, a major 4.6 kb and a minor 3.5 kb mRNAs, in the kidney, gill and intestine.

3' Untranslated Regions↗
PubMed2000

Prevalence of subclinical cryoglobulinemia in maintenance hemodialysis patients and kidney transplant recipients.

We studied the prevalence and the clinical spectrum of cryoglobulinemia (Cryo) among 101 maintenance hemodialysis (HD) patients and 148 kidney transplant (KT) recipients, with or without chronic hepatitis C virus (HCV) infection. Cryo was present in 32% (16 of 50) of the HCV-positive HD patients, 5.9% (3 of 51) of the HCV-negative HD patients, 37.8% (28 of 74) of the HCV-positive KT recipients, and 27% (20 of 74) of the HCV-negative KT recipients. Cryoprecipitate in 56.3% (9 of 16) of the HCV-positive Cryo HD patients and 53.8% (14 of 26) of the HCV-positive Cryo KT recipients contained HCV-RNA. Interestingly, the cryocrit values among HD and KT patients were much lower than these in other reports on nonrenal failure cases. Also, the cryoglobulinemic syndrome (with purpura, arthralgia, etc.) in HD and KT patients with Cryo were not common (Tables 1 and 2). There was not correlation between Cryo and age,sex, and liver function. Only longer duration of end-stage renal disease was noted in these patients. In addition, we suggested that KT patients are more susceptible to having Cryo. Further studies are necessary to better define whether any other subclinical viral or nonviral chronic infection may induce Cryo in HCV-negative KT recipients.

Adult↗
PubMed2000

Muscle regulatory factor gene: zebrafish (Danio rerio) myogenin cDNA.

Myogenin is one of the basic helix-loop-helix proteins that regulate muscle-specific gene expression. Using reverse transciption-polymerase chain reaction (RT-PCR), 5'- and 3'-rapid amplification of cDNA ends (RACE), zebrafish myogenin cDNA was cloned from mRNA of embryos at 10-96 h post-fertilization. The cDNA, at 1384 base pairs (bp), contained a 771-bp open reading frame with 113- and 500-bp flanking regions at the 5'- and 3'-ends, respectively. The deduced amino acid sequences of zebrafish myogenin encoded a 256-amino-acid polypeptide. In a comparison with myogenin of carp, trout, Xenopus, chicken and human, zebrafish myogenin shared 90.9, 77.6, 70.3, 62.9 and 51.5% amino acid identity, respectively. The basic helix-loop-helix domains in myogenin are all conserved. The molecular phylogenic tree demonstrated that myogenin of zebrafish is more closely related to that of fish than to the myogenin of other vertebrates.

Amino Acid Sequence↗
PubMed2000

Effects of porcine reproductive and respiratory syndrome virus (isolate tw91) on porcine alveolar macrophages in vitro.

To verify the role of porcine reproductive and respiratory syndrome virus (PRRSV) infection on pulmonary defense mechanisms, alterations in the viability, morphology, and various functions of porcine alveolar macrophages (AMs) were evaluated in vitro for 2-72 h after exposure to a Taiwan isolate, tw91, at a multiplicity of infection (MOI) of 0.1. A low but constant rate of infection, around 5%, was seen in AMs from the PRRSV-infected group throughout the study. When compared with a mock-infected group, AMs from the PRRSV-infected group had a significantly lower viability at 18-72 h post-infection (HPI) as determined by trypan blue dye exclusion. Also during this time period, the cells showed morphological changes, including rounding, bleb formation, and rupture. The phagocytic and microbicidal capacity of AMs against Candida albicans was significantly inhibited after 6 HPI. Although the total amount of superoxide anion (O2-) and hydrogen peroxide (H2O2) produced by the AMs was reduced after 18 and 12 HPI, respectively, the amount of production was enhanced in both reactive oxygen species on a per viable cell basis after 12 HPI. In contrast, the level of bioactive tumor necrosis factor alpha (TNF-alpha) secretion, either total or on a per viable cell basis, was markedly reduced soon after PRRSV infection, up to 36 HPI, followed by a rebound thereafter. Prostaglandin E2 (PGE2) production was enhanced, both in total and on a per viable cell basis, in the first 6 h of infection, especially at 2 HPI. However, it became lower than that of the control after 36 HPI. The results indicated that PRRSV infection could cause, directly and/or indirectly, not only death of AMs but also adverse alterations in their morphology and function, although some of the effects seemed to be reversible. Because AMs are crucial to the host against airborne pathogens, PRRSV infection may potentially predispose pigs to secondary pulmonary infections.

Animals↗
PubMed2000

Inhibition of xanthine oxidase by some Chinese medicinal plants used to treat gout.

The enzyme xanthine oxidase catalyses the oxidation of hypoxanthine to xanthine and then to uric acid, which plays a crucial role in gout. A total of 122 traditional Chinese medicinal plants, selected according to the clinical efficacy and prescription frequency for the treatment of gout and other hyperuricemia-related disorders, have been evaluated for the enzyme inhibitory activity. Among the 122 methanol extracts derived from these species, 69 were shown to be inhibitory at 100 microg/ml, with 29 having greater than 50% inhibition. As to the equal amount of water extracts, 40 were disclosed to be active at 100 microg/ml, with 13 possessing more than 50% inhibition. At 50 microg/ml, 58 methanol and 24 water extracts exhibited inhibitory activity, with 15 of the former and two of the latter showing greater than 50% inhibition. The most active was the methanol extract of the twig of Cinnamomum cassia (Lauraceae) (IC(50), 18 microg/ml), which was followed immediately by those of the flower of Chrysanthemum indicum (Asteraceae) (IC(50), 22 microg/ml) and the leaves of Lycopus europaeus (Lamiatae) (IC(50), 26 microg/ml). Among the water extracts, the strongest inhibition of the enzyme was observed with that of the rhizome of Polygonum cuspidatum (Polygonaceae) (IC(50), 38 microg/ml). The IC(50) value of allopurinol used as a positive control was 1.06 microg/ml. The study demonstrated that the effects for these medicinal plants used for the gout treatment were based, at least in part, on the xanthine oxidase inhibitory action.

Enzyme Inhibitors↗
PubMed2000

Impact of interleukin-1 receptor antagonist and tumor necrosis factor-alpha gene polymorphism on IgA nephropathy.

BACKGROUND: It is evident that cytokines play an important role in the pathogenesis as well as disease progression in IgA nephropathy (IgAN). The level of cytokine production is influenced by different genotypes that reflect gene polymorphism of the pertinent cytokine. Interleukin-1 receptor antagonist (IL-1ra) and tumor necrosis factor-alpha (TNF-alpha) gene polymorphism have been found to affect disease susceptibility and activity in several inflammatory diseases. However, the impact of these polymorphisms in IgAN patients has not previously been thoroughly studied. METHODS: We investigated 111 cases of biopsy-proven IgAN and 100 healthy, normal controls for their IL-1ra and TNF-alpha gene polymorphism. IL-1ra gene polymorphism was characterized as a variable number of tandem repeats of a 86 bp sequence within intron 2. Five alleles were identified and were designated as IL1RN*1, IL1RN*2, IL1RN*3, IL1RN*4, and IL1RN*5, corresponding to 4, 2, 5, 3, 6 repeats, respectively. A polymorphism in the promoter region of the TNF-alpha gene was also studied. This polymorphism involved a guanidine to adenosine transition at position -308 and was designated as TNF1 (-308G) and TNF2 (-308A). RESULTS: There were 54 male and 57 female patients with a mean age of 30.3 +/- 12.5 years and a disease duration of 66. 8 +/- 47.2 months. The mean duration of the follow-up period was 47. 3 +/- 32.6 months. In the patient group, the allele frequencies of IL1RN*1, IL1RN*2, IL1RN*3, IL1RN*4, and IL1RN*5 were 89.6%, 9.9%, 0%, 0.5%, and 0%, respectively, whereas the corresponding carriage rates were 100%, 19.8%, 0%, 0.9%, and 0%, respectively. An excessive carriage of IL2RN*2 was found in the patients when compared with normal controls (allele frequency, 9.9 vs. 2.5%, P < 0.0001). The allele frequencies of TNF1 and TNF2 were 94.1 and 5.9%, respectively, and the carriage rates were 99.1 and 10.8%, respectively, in the patients, which was not significantly different from those of normal controls. When the patients were stratified into mild and severe groups according to their initial presentation, none of the studied alleles correlated with the severity. However, patients with gross hematuria were associated with a higher carriage rate of TNF2 when compared with patients without gross hematuria (allele frequency, 15. 4 vs. 4.6%, P = 0.0552; carriage rate, 30.8% vs. 8.2%, P = 0.0272). Renal survival analysis revealed that the TNF2 carrier had a renal survival comparable with TNF2 (-) patients. However, the carriage of the IL1RN*2 allele was associated with a significantly poorer long-term outcome with a median survival time of 72 months, as compared with those without IL1RN*2 (134 months, P < 0.01). CONCLUSION: IL-1ra and TNF-alpha gene polymorphism may affect disease susceptibility as well as disease activity and long-term outcome in human IgAN. Treatment with an IL-1ra or IL-1 blocking agent may be relevant in those carrying the IL1RN*2 allele.

Adolescent↗
PubMed2000

Nutritional status of mechanically ventilated critically ill patients: comparison of different types of nutritional support.

Malnutrition is a common problem in hospitalized patients. Early assessment of nutritional status may help in identifying patients for whom nutritional interventions are needed. The purpose of this study was to assess and compare the nutritional status of mechanically ventilated critically ill patients who were receiving nutritional support. Forty-nine patients were divided into either enteral nutrition, total parenteral nutrition or combined (enteral plus total parenteral nutrition) groups. Anthropometric and biochemical measurements, and medical status (APACHE II score) were assessed at the 1st day and 14th day of admission in the intensive care unit (ICU) of Taichung Veteran General Hospital. The length of ventilator dependency was significantly positively correlated with calorie and carbohydrate intake in the pooled group. Patients receiving enteral and combined nutrition showed significantly lower anthropometric measurements at the 14th day after admission. Patients in all groups had abnormal mean biochemical values at the 1st day of admission. Subjects in the combined group showed a significant increase in prealbumin and the Maastricht Index levels after 14 days. Patients in all three groups were malnourished when admitted to the ICU. Patients showed a slightly improvement of nutritional status after receiving nutritional support for 14 days.

APACHE↗
PubMed2000

Assessment of nutritional status in continuous ambulatory peritoneal dialysis patients: a comparison of bioelectric impedance and conventional methods.

BACKGROUND: Nutritional status is an important factor in long term continuous ambulatory peritoneal dialysis (CAPD) prognoses. Conventionally, serum albumin is an indicator of nutritional status. More recently, protein catabolic rate and lean body mass have been calculated during peritoneal equilibrium testing to assess nutritional status. These have the advantage of providing an early indication of malnutrition before the serum albumin decreases. Bioelectric impedance analysis (BIA) of nutrition has the advantage of being the simplest procedure among all nutritional assessments. Standard nutritional assessments was compared with the BIA method. METHODS: The protein catabolic rate and lean body mass was measured by the Keshaviah method. At the same time BIA was used to assess lean body mass, fat mass and fixed percentage of fat in 27 long-term CAPD patients, with and without peritoneal fluids. RESULTS: Among the 27 patients, the protein catabolic rate was 0.95+/-0.5 g/kg/day and lean body mass was 37.4+/-0.5 kg measured by the conventional method. Using BIA, the lean body mass was 37.8+/-11.0 kg with peritoneal dialysate, which was strongly correlated with the conventional method (p<0.001). BIA of lean body mass was 37.4+/-9.2 kg without peritoneal dialysate, which was also significantly correlated to the conventional method (p<0.001). CONCLUSIONS: BIA nutritional assessment of lean body mass was comparable to the conventional method of nutritional assessment. The presence or absence of peritoneal dialysate did not influence the BIA method for detection of lean body mass. BIA has the advantage of being a more simple procedure and can be used for the long-term assessment of nutritional status in CAPD patients.

Blood Urea Nitrogen↗
PubMed2000

In vitro inhibition of rat monoamine oxidase by liquiritigenin and isoliquiritigenin isolated from Sinofranchetia chinensis.

AIM: To study the inhibition of liquiritigenin (1) and isoliquiritigenin (2) isolated from Sinofranchetia chinensis on rat monoamine oxidase A and B (MAO A and B). METHODS: Rat brain mitochondrial fraction, prepared by differential centrifugation, was utilized as a source of MAO activity. MAO activity was determined radiochemically with [14C]5-hydroxytryptamine (5-HT) and [14C]beta-phenylethylamine (beta-PEA) used as MAO A or B specific radiolabled substrates, respectively. The Ki and KI values were obtained from Lineweaver-Burk plot using linear regression analysis. RESULTS: Liquiritigenin and isoliquiritigenin were found to be inhibitory against both MAO A and B in a dose-dependent manner. IC50 (95% of confidence limits) of liquiritigenin and isoliquiritigenin were 32 (26-36) and 13.9 (12.8-15.6) mumol/L for the inhibition of MAO A, and 104.6 (89.0-118.9) and 47.2 (39.5-54.5) mumol/L for that of MAO B, respectively. Lineweaver-Burk transformation of the MAO A inhibition data indicated that the inhibition was non-competitive for both liquiritigenin and isoliquiritigenin whereas their inhibition of MAO B was of mixed type. Regarding MAO A inhibition, the Ki values of liquiritigenin and isoliquiritigenin were 31.5 mumol/L and 14.3 mumol/L, respectively. As to the inhibition of MAO B, the Ki and KI data for liquiritigenin were 164.7 and 15.2 mumol/L, and those for isoliquiritigenin were 62.2 and 9.3 mumol/L, respectively. CONCLUSION: Liquiritigenin and isoliquiritigen inhibited the activity of MAO A and B in rat brain mitochondria, and the latter was more active than the former.

Animals↗
PubMed1999

C(60) and water-soluble fullerene derivatives as antioxidants against radical-initiated lipid peroxidation.

C(60), vitamin E, and three C(60) derivatives (polar 1 and water-soluble C(3)/D(3)C(60)s) were examined for their antioxidant effects on prevention of lipid peroxidation induced by superoxide and hydroxyl radicals. The protection effect on lipid peroxidation was found to be in the sequence: C(60) >/= vitamin E > 1 > none, for liposoluble antioxidants, and C(3)C(60) >> D(3)C(60) > none, for water-soluble ones. Fluorescence quenching of PyCH(2)COOH (Py = pyrene) by both C(3)- and D(3)C(60)s shows that the Stern-Volmer constant, K(SV), is about the same for both quenchers in aqueous solution. Upon addition of liposomes, the fluorescence quenching becomes more efficient: 5-fold higher in K(SV) for C(3)C(60) than for D(3)C(60). When Py(CH(2))(n)()COOH (n = 1, 3, 5, 9, or 15) was incorporated in lipid membranes, the K(SV)s all were small and nearly equal for D(3)C(60) but were quite large and different for C(3)C(60) with the sequence: n = 1 < 3 < 5 < 9 < 15. The better protection effect of C(3)C(60) on lipid peroxidation than that of D(3)C(60) is attributed to its stronger interaction with membranes. Overall, the antioxidation abilities of the compounds examined were rationalized in terms of the number of reactive sites, the location of antioxidant in lipid membranes, and the strength of interactions between antioxidants and membranes.

Antioxidants↗
PubMed1999

Suppression of ultraviolet irradiation-induced apoptosis by overexpression of focal adhesion kinase in Madin-Darby canine kidney cells.

Focal adhesion kinase (FAK) has been implicated to play a role in suppression of apoptosis. In this study, we have demonstrated that UV irradiation induced cleavage of FAK and two of its interacting proteins Src and p130(Cas) in Madin-Darby canine kidney cells, concomitant with an increase in cell death. The cleavage of these proteins upon UV irradiation was completely inhibited by ZVAD-FMK, a broad range inhibitor of caspases, and apparently delayed by Bcl2 overexpression. To examine if FAK plays a role in suppressing UV-induced apoptosis, stable Madin-Darby canine kidney cell lines overexpressing FAK were established. Our results showed that a marked (30-40%) increase in cell survival upon UV irradiation was achieved by this strategy. In our efforts to determine the mechanism by which FAK transduces survival signals to the downstream, we found that a FAK mutant deficient in binding to phosphatidylinositol 3-kinase failed to promote cell survival. Moreover, the expression of the Src homology 3 domain of p130(Cas), which competed with endogenous p130(Cas) for FAK binding, abrogated the FAK-promoted cell survival. Together, these results suggest that the integrity of FAK and its binding to phosphatidylinositol 3-kinase and p130(Cas) are required for FAK to exert its antiapoptotic function.

Animals↗
PubMed1999

Modulation of emesis by fentanyl and opioid receptor antagonists in Suncus murinus (house musk shrew).

The anti-emetic mechanism of action of fentanyl to inhibit nicotine (5 mg/kg, s.c.)-induced emesis was investigated in Suncus murinus. The anti-emetic action of fentanyl (40 microg/kg, s.c.) was antagonised by the opioid receptor antagonists naltrexone (1 mg/kg, s.c.), naloxone (1 mg/kg, s.c.), M8008 (16S-methylcyprenorphine; 1 mg/kg, s.c.) and MR 2266 (5,9-diethyl-2-(3-furylmethyl)2'-hydroxy-7,7-benzomorphan; 1 mg/kg) but not by naloxone methylbromide (1 mg/kg, s.c.), naloxone methyliodide (1 mg/kg, s.c.), naltrindole (1 mg/kg, s.c.), DIPPA (2-(3,4-dichlorophenyl)-N-methyl-N-[1S)-1-(3-isothiocyanatophenyl)-2-(1- pyrrolidinyl)-ethyl]acetamide; 3 mg/kg, i.p.) or naloxonazine (35 mg/kg, i.p.). This indicates an involvement of mu2-opioid receptors within the brain to mediate the anti-emetic effect of fentanyl. In other studies, naloxone 10-60 mg/kg, s.c. induced dose-related emesis but naltrexone was only emetic at 60 mg/kg, s.c. and naloxone methylbromide failed to induce emesis at doses up to 60 mg/kg, s.c. The emesis induced by a high dose of naloxone 60 mg/kg, s.c. was antagonized by CP-99,994 ((+)-(2S,3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine; 3-30 mg/kg, i.p.), 8-OH-DPAT, ((+/-)-8-hydroxy-dipropylaminotetralin; 0.003-0.3 mg/kg, s.c.), buspirone (3 mg/kg, s.c.) and fluphenazine (1-3 mg/kg, i.p.) but not by naltrexone (1-30 mg/kg, s.c.), metoclopramide (0.3-3 mg/kg, i.p.), sulpiride (0.3-3 mg/kg, i.p.), domperidone (0.1-3 mg/kg, i.p.), ondansetron (0.3-3 mg/kg, i.p.), granisetron (0.3-3 mg/kg, i.p.), scopolamine (0.3-3 mg/kg, i.p.) or promethazine (0.3-3 mg/kg, i.p.). The data is discussed in relation to opioid receptor mechanisms moderating emesis and the identification of potential sites of drug action available to inhibit the emetic reflex.

Animals↗