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C Liu

Publications and source records attributed to C Liu.

At least 145 records · Page 8Linked to original sources
PubMed2001

Cloning and pharmacological characterization of a fourth histamine receptor (H(4)) expressed in bone marrow.

Histamine is a multifunctional hormone that regulates smooth muscle contraction in the airways, acid secretion in the gut, and neurotransmitter release in the central nervous system through three well characterized receptor subtypes, H(1), H(2), H(3), respectively. As part of a directed effort to discover novel G-protein-coupled receptors through homology searching of genomic databases, we identified a partial clone (GPCR105) that had significant homology to the recently identified histamine H(3) receptor cDNA. Expression of the full-length human GPCR105 in cells confers the ability to bind [(3)H]histamine with high affinity (K(D) = 5 nM). GPCR105 is pharmacologically similar to the histamine H(3) receptor in that it binds many of the known H(3) agonists and antagonists, albeit with a different rank order of affinity/potency. GPCR105 does not bind (i.e., K(D) > 10 microM) all tested H(1) and H(2) receptor antagonists such as diphenhydramine, loratadine, ranitidine, and cimetidine, but has modest affinity for the H(2) receptor agonist, dimaprit (377 nM). Whereas the H(3) receptor is expressed almost exclusively in nervous tissues, GPRC105 is expressed primarily in bone marrow and eosinophils. Together, these data demonstrate that GPCR105 is a novel histamine receptor structurally and pharmacologically related to the H(3) receptor. However, its unique expression profile and physiological role suggest that GPCR105 is a fourth histamine receptor subtype (H(4)) and may be a therapeutic target for the regulation of immune function, particularly with respect to allergy and asthma.

Adenylyl Cyclases↗
PubMed2001

Induction of caspase-dependent apoptosis in cultured cells by the avian coronavirus infectious bronchitis virus.

Avian coronavirus infectious bronchitis virus (IBV) is the causative agent of chicken infectious bronchitis, an acute, highly contagious viral respiratory disease. Replication of IBV in Vero cells causes extensive cytopathic effects (CPE), leading to destruction of the entire monolayer and the death of infected cells. In this study, we investigated the cell death processes during acute IBV infection and the underlying mechanisms. The results show that both necrosis and apoptosis may contribute to the death of infected cells in lytic IBV infection. Caspase-dependent apoptosis, as characterized by chromosomal condensation, DNA fragmentation, caspase-3 activation, and poly(ADP-ribose) polymerase degradation, was detected in IBV-infected Vero cells. Addition of the general caspase inhibitor z-VAD-FMK to the culture media showed inhibition of the hallmarks of apoptosis and increase of the release of virus to the culture media at 16 h postinfection. However, neither the necrotic process nor the productive replication of IBV in Vero cells was severely affected by the inhibition of apoptosis. Screening of 11 IBV-encoded proteins suggested that a 58-kDa mature cleavage product could induce apoptotic changes in cells transiently expressing the protein. This study adds one more example to the growing list of animal viruses that induce apoptosis during their replication cycles.

Amino Acid Chloromethyl Ketones↗
PubMed2001

Human herpesvirus 8 (HHV-8)-encoded cytokines induce expression of and autocrine signaling by vascular endothelial growth factor (VEGF) in HHV-8-infected primary-effusion lymphoma cell lines and mediate VEGF-independent antiapoptotic effects.

The potential roles of human herpesvirus 8 (HHV-8) cytokines in HHV-8 pathogenesis were investigated by determining the expression of the HHV-8 chemokines viral macrophage inflammatory protein 1A (vMIP-1A) and vMIP-1B in primary effusion lymphoma (PEL)-derived cell lines and examining the signaling activities of these chemokines and HHV-8-encoded vIL-6 in these cells. Secreted vMIP-1A and vMIP-1B were detected in biologically significant concentrations following tetradecanoyl phorbol acetate treatment, which induces productive replication. vIL-6 and vMIP-1A, added exogenously to cultures of four different PEL cell lines, induced the expression of vascular endothelial growth factor type B (VEGF-B) and VEGF-A, respectively. These cells were found to express VEGF receptor 1 (Flt-1) protein, and signaling by recombinant VEGF-A(165) was demonstrated for two of the PEL cell lines, indicating the potential for autocrine, as well as paracrine, effects of viral cytokine-induced VEGF. In addition, vMIP-1A and vMIP-1B, but not VEGF-A(165), were found to inhibit chemically induced apoptosis in PEL cells. Our data suggest that vIL-6 and vMIP-1A may influence PEL through VEGF autocrine and paracrine signaling that promotes PEL cell growth and extravascular effusion and that vMIP-1A and vMIP-1B can act independently of VEGF as antiapoptotic factors.

Animals↗
PubMed2001

Primary polypseudophakia for cataract surgery in hypermetropic eyes: refractive results and long term stability of the implants within the capsular bag.

AIM: To determine the long term visual and refractive results, and stability and complications of primary polypseudophakia using poly(methylmethacrylate) (PMMA) intraocular lenses (IOLs) for cataract surgery in hypermetropic eyes. METHODS: Prospective study of 15 short or hypermetropic eyes undergoing phacoemulsification with primary polypseudophakia with two PMMA IOLs implanted within the capsular bag. RESULTS: The spherical equivalent was reduced from a mean +4.87 (SD 3.00) dioptres (D) to -0.12 (1.40 D), and the deviation from the intended refraction was +0.005 (1.30) D, 23.6 (12.36) months post-implantation. The deviation from intended refraction was not statistically significant (p = 0.989; paired t test). Postoperative best corrected visual acuity (BCVA) was 6/12 or better in all eyes without macular or optic nerve co-morbidity. Interlenticular opacification (ILO) in the form of peripheral Elschnig pearls was seen in four (26.67%) eyes. A new type of ILO in the form of usually pigmented deposits in the central interface developed in five (33.33%) eyes and resulted in the appearance of Newton's rings in three. None of the eyes with ILO had any loss of BCVA or hyperopic shift. Six (40%) eyes were within 1 D from the intended refraction and 14 (93.33%) within 2 D. There was no statistically significant difference in the accuracy of the two intraocular lens calculation formulas used (SRK II and SRK/T). CONCLUSION: Peripheral Elschnig pearl-type ILO can occur as a late complication of primary in the bag implantation of two PMMA IOLs. A new type of ILO is described. Both types of ILO have not to date resulted in deterioration of visual acuity in our cohort. Use of appropriate biometry techniques and IOL calculation formulas may yield more accurate refractive results.

Aged↗
PubMed2001

Interlenticular opacification in piggyback AcrySof intraocular lenses: explantation technique and laboratory investigations.

BACKGROUND/AIMS: Interlenticular opacification (ILO) is a recognised complication of piggyback intraocular lenses (IOLs). The aetiology, histopathology, and treatment are not clearly defined, however. METHODS: Two pairs of AcrySof IOLs were explanted from a patient with bilateral ILO. The explantation technique and surgical challenges of IOL exchanges are described. The explanted IOL complexes and a sample of the anterior capsule were examined by phase, polarising, and immunofluorescence microscopy. RESULTS: A 50 year old man developed ILO bilaterally after piggyback AcrySof IOL implantation. A central contact zone was surrounded by a homogeneous paracentral opacity possibly consisting of extracellular matrix previously laid down by proliferating lens epithelial cells (LECs). These opacities were in turn surrounded by interlenticular Elschnig pearl-type opacities contiguous with the same material filling the periphery of the capsular bag. The IOL complexes were very adherent to the capsular bag and they had to be separated with the help of high viscosity viscoelastic before a single one piece PMMA IOL implantation via large limbal incisions. The sample of anterior capsule showed a ridge configuration from the piling of LECs in the site of apposition with the anterior capsule and cells showing different characteristics on either side of the ridge. CONCLUSION: Cellular proliferation, deposition of ECM from proliferating LECs, and capsular changes induced by cell metaplasia may lead to ILO formation in piggyback AcrySof IOLs. Careful separation of the AcrySof IOL complex from the capsule, meticulous clean up of the proliferating material, and implantation of single or dual in the bag PMMA IOLs through a large incision with capsulorrhexis enlargement may help in the prevention of recurrence of interface opacification.

Cataract↗
PubMed2001

Regulation of left-right asymmetry by thresholds of Pitx2c activity.

Although much progress has been made in understanding the molecular mechanisms regulating left-right asymmetry, the final events of asymmetric organ morphogenesis remain poorly understood. The phenotypes of human heterotaxia syndromes, in which organ morphogenesis is uncoupled, have suggested that the early and late events of left-right asymmetry are separable. The Pitx2 homeobox gene plays an important role in the final stages of asymmetry. We have used two new Pitx2 alleles that encode progressively higher levels of Pitx2c in the absence of Pitx2a and Pitx2b, to show that different organs have distinct requirements for Pitx2c dosage. The cardiac atria required low Pitx2c levels, while the duodenum and lungs used higher Pitx2c doses for normal development. As Pitx2c levels were elevated, the duodenum progressed from arrested rotation to randomization, reversal and finally normal morphogenesis. In addition, abnormal duodenal morphogenesis was correlated with bilateral expression of Pitx2c. These data reveal an organ-intrinsic mechanism, dependent upon dosage of Pitx2c, that governs asymmetric organ morphogenesis. They also provide insight into the molecular events that lead to the discordant organ morphogenesis of heterotaxia.

Alleles↗
PubMed2001

Some failure modes of four clinical bone cements.

The fracture or failure behaviours of four commercial acrylic-based bone cements have been examined in tensile, bending and compression modes, and their mechanical properties are reviewed. It was found that Palacos R-40 bone cement had high radiopaque agent concentration, with high surface hardness. It exhibited a much lower bending strength and bending modulus compared with the other three bone cements (CMW1, CMW2000 and Simplex P). The textures of tensile fracture surfaces produced were similar for the four bone cements studied. The fracture surface was fragmented by crevices, which developed through the matrix and around large undissolved polymethylmethacrylate (PMMA) beads. Three bands with different features existed on the bending fracture surfaces, with an abrupt transition between them. It appears that the agglomerates of zirconium dioxide particles are implicated in Palacos R-40 bone cement fracture surface. The examination of compressive failed specimens revealed that a 'yielded crack band' existed across the transverse section. Plastic deformation resulted in the PMMA beads being squashed in the longitudinal direction and dilated in the transverse direction.

Biomechanical Phenomena↗
PubMed2001

Enhanced regeneration of rice (Oryza sativa L.) embryogenic callus by light irradiation in growth phase.

The effect of light irradiation on the growth and regeneration of embryogenic rice calli was investigated. Rice calli grew slightly better in the light than in the dark during the growth stage. When calli subcultured under light irradiation were transferred into a liquid regeneration culture system, the number of plantlets with shoots regenerated from calli subcultured in the light was higher than in the case of those subcultured in the dark, whereas there was no obvious difference between the light and dark subcultures when a solid medium was used for the regeneration. The number of regenerated plantlets increased with increasing light intensity up to 2000 lx, but remained the same when the light intensity was raised further. The maximum number of regenerated plantlets was obtained under a photoperiod of 16 h/d. About 8800 plantlets per liter-medium were regenerated from light-cultured calli, which is 1.5 times more than the number regenerated from calli grown in the conventional dark culture.

Journal Article↗
PubMed2001

Aurintricarboxylic acid exerts insulin-like growth stimulating effects on Chinese hamster ovary cells under serum-free conditions.

When aurintricarboxylic acid (ATA) was added at a concentration of 30 mg/l in DME/F12 medium to Chinese hamster ovary (CHO) NTHU-108 cells in static six-well plates, some of the cells exhibited adherent growth while others grew in suspension. Beyond the critical concentration of ATA, CHO cells grew in single-cell suspension. In the same serum-free medium, insulin at a level of 0.5 mg/l was found to be the most important protein ingredient promoting cell growth. We used the respective kinase inhibitors to investigate their influence on the cell proliferation induces by ATA and insulin. It is interesting that the inhibition by seven kinase inhibitors of ATA-induced proliferation is similar to that of insulin-induced proliferation. It is possible that ATA mimics insulin and influences the mitogen activated signal transduction to induce the proliferation of CHO cells. Although the actual mechanism of the proliferation of CHO cells by ATA is unclear, ATA supported the long-term proliferation of CHO cells under serum-free conditions and thus could be used as a good substitute for insulin in the formulation of protein-free media.

Journal Article↗
PubMed2001

Pentanoic acid, a novel protein synthesis stimulant for Chinese Hamster Ovary (CHO) cells.

Nine carboxylic acids were tested to evaluate their effects on recombinant fusion protein production and cell growth of Chinese Hamster Ovary (CHO) cells. Pentanoic acid was demonstrated to have the highest enhancement effect on the protein biosynthesis of CHO cells among the acids tested. Pentanoic acid also had less growth suppression effects compared with butyrate. The optimal induction time and concentration of pentanoic acid for a 120-h batch culture were 72 h and 1 mM, respectively. Apoptosis (programmed cell death) was observed in the serum-free batch culture of CHO cells using a cell death detection ELISA kit. The addition of butyrate accelerated the rate of apoptosis of CHO cells whereas the addition of pentanoate did not. These results confirmed that pentanoic acid was a better stimulant for protein biosynthesis in animal cell culture than butyrate.

Journal Article↗
PubMed2001

In situ regeneration of rice (Oryza sativa L.) callus immobilized in polyurethane foam.

An in situ regeneration system for rice calli comprised of a callus growth stage and two regeneration stages was developed. After the first stage of regeneration, the medium is changed and the calli are immobilized in polyurethane foam supports, in each of which 3-5 regenerated plantlets develop from the immobilized calli during the second stage. While no significant change in callus size was observed during the first stage of regeneration, in the second stage callus enlargement and shoot regeneration predominated. In the light of these findings, calli were immobilized in the second stage after medium exchange. The use of 10-mm support cubes with an average pore size of 3.6 mm resulted in the most efficient immobilization and in situ regeneration. Medium exchange after 15 d gave the largest number of support cubes with shoots. When rice calli were cultivated in support cubes placed in 60 ml second-stage medium in a 500-ml flask, the immobilization ratio was 83%, and 82% of the support cubes contained 3-5 regenerated plantlets after 25 d. The shoot lengths of the regenerated plantlets obtained from the in situ regeneration culture were longer than those from a suspension culture. When support cubes with 3-5 regenerated plantlets were transferred from the flask to 1 4 MS solid medium supplemented with 10 g/l sorbitol and 5 g/l sucrose, the regenerated plantlets developed quickly into plants with a length above 10 cm after 10 d.

Journal Article↗
PubMed2001

A serodiagnostic ELISA using recombinant antigen of swine transmissible gastroenteritis virus nucleoprotein.

A serodiagnostic ELISA utilizing the recombinant nucleoprotein (rN protein) of transmissible gastroenteritis virus (TGEV) was developed, and evaluated by examining a panel of 141 virus neutralization (VN) positive and 101 negative sera. The rN protein-based ELISA (rnELISA) appeared to be highly sensitive and specific (98.6% and 98.0%, respectively) when it was compared to the VN test. The result was similar to that of an ELISA based on purified viral antigens with showing good correlation (R=0.829). No cross-reaction was detected with antisera against porcine epidemic diarrhea virus, hog cholera virus, type A rotavirus, pseudorabies virus and swine vesicular disease virus in this ELISA. The rnELISA can be an alternative for the diagnosis of TGE with a great advantage in antigen preparation.

Animals↗
PubMed2001

Relationship of aneurysmal subarachnoid hemorrhage to changes in atmospheric pressure: results of a prospective study.

OBJECT: The purpose of this study was to evaluate the relationship between atmospheric pressure and subarachnoid hemorrhage (SAH) in a region in the English Midlands. METHODS: All patients with angiographically proven SAH for the calendar year 1998 were analyzed. A geographical allocation was made based on the patients' origin within the region. The events were then compared with the data available for the local atmospheric pressures. One hundred nine patients had an SAH during the time period studied. The median atmospheric pressure recorded was 1014.5 millibars. Atmospheric pressure was modestly correlated with the number of SAHs per day (Spearman's rank correlation, r = 0.33; p < 0.0001); the daily change in atmospheric pressure also correlated mildly (r = 0.34, p < 0.0001). No other statistically significant association was found. CONCLUSIONS: The authors have shown a relationship between high atmospheric pressure and increased incidence of SAH. The underlying reason for this remains obscure.

Atmospheric Pressure↗
PubMed2001

Expression of metalloproteinases and its inhibitor in later stage of rabbit neointima development.

Neointima formation after arterial de-endothelialization refers not only to smooth muscle cell (SMC) migration and proliferation, but also involves extracellular matrix (ECM) metabolism. Most studies regarding the role of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in neointima have focused on the early phase of vascular remodeling. In this study, we examined the expression of MMP and TIMP in rabbit aortic neointima at a relatively late stage of lesion development, between 4 and 12 weeks after initial de-endothelialization. Northern blot analysis revealed expression of steady-state MMP-9 mRNA was increased up to the 4th week and MMP-2 mRNA to the 12th week after de-endothelialization. In situ hybridization shown that MMP positive cells were predominantly distributed in arterial neointima. Expression of TIMP-1 mRNA was continuously up-regulated up to the 12th week and TIMP-1 positive cells, primarily SMCs, were also localized to the neointimal tissue. Alteration at mRNA level was accompanied by that at protein level, as assessed by SDS-PAGE zymography for MMPs and immunoblotting for TIMP-1. The profile of alteration at protein level correlated well with that at mRNA level. These data suggest that synthesis of MMPs and TIMP is a prolonged process and arterial SMC is a major source of MMP production in arterial neointima. Enhanced synthesis of MMPs and TIMPs at late stage of neointimal development may contribute to arterial ECM metabolism.

Animals↗
PubMed2001

[A study of phenylketonuria heterozygotes screening in married population of Tianjin area].

OBJECTIVE: To find out a method that is simple and reliable for screening phenylketonuria(PKU) heterozygotes. METHODS: Detecting and analyzing plasma phenylalanine(Phe) and tyrosine(Tyr) from 101 known-PKU heterozygotes and 2023 married people by means of a high performance liquid chromatograph. RESULTS: Significant differences were observed between known- PKU heterozygotes and screening population in plasma Phe, Phe/Tyr and Phe(2)/Tyr. The values of plasma Phe, Phe/Tyr and Phe(2)/ Tyr from 94.1% known-PKU heterozygotes were higher than mean+2s of those values from screening population. According to the limits of mean+2s, 81 cases were screened out from the 2023 married people. It was the first time to get the actual heterozygote frequency of 4% from population. CONCLUSION: The biochemical method mentioned above is available for use in screening PKU heterozygotes.

Adult↗
PubMed2001

The structure, frequency, and forensic application of the STR locus D16S543 in the Japanese population.

D16S543 is a complex STR locus consisting of five types of repeat units. The frequency distribution and genetic characteristics of this locus in Japanese were investigated using blood samples from 124 unrelated Japanese and 15 families. Alleles were detected using denatured polyacrylamide gels followed by automated analysis on an ABI 373 sequencer using Genescan software 672. Twenty-one alleles were identified, ranging in size from 281 to 489 bp. An allelic ladder containing the 21 alleles was constructed and used as a typing standard. The repeat unit arrays allowed the 21 alleles to be classified into three distinct groups, including alleles 1 to 7 in group I, alleles 8 to 14 in group II, and alleles 15 to 22 in group III. The alleles in group II were characterized by the insertion of one repeat unit of CAGG, one of AAAG, and three of AAGG, while the group III alleles differed from those of groups I and II by the insertion of a total of 32 repeat units ranging in 5 types. Within each group, the alleles differed from each other only in one 5' side tetranucleotide AAGG. The power of discrimination (Pd) and the estimated heterozygosity were calculated to be 0.989 and 0.934, respectively. Typing of this locus was successfully applied in four old forensic materials. The study presented herein demonstrates that D16S543 is a highly polymorphic and applicable locus in Japanese.

Alleles↗
PubMed2001

Extended photoreceptor viability by light stress in the RCS rats but not in the opsin P23H mutant rats.

PURPOSE: To determine the effect of light stress on retinal function and long-term photoreceptor viability in Royal College of Surgeons (RCS) rats and the applicability of the light treatment to the opsin P23H mutant rats. METHODS: RCS rats at postnatal day (P)23 were illuminated with 120 foot-candles (fc) white light for 10 hours. Photoreceptor survival and basic fibroblast growth factor (bFGF) expression were measured at P60 and P83. Retinal function was evaluated by electroretinography. Opsin P23H transgenic rats were treated with light at P28 and analyzed at P70 for photoreceptor viability, ultrastructure, and bFGF expression. RESULTS: Light-treated RCS rats at P60 had four to five rows of nuclei versus one to two rows in untreated littermates. The average amplitude of the ERG b-wave was 28 microV in treated rats, compared with 6 microV in untreated littermates. By P83 there was still significant preservation of the ONL in treated rats. Immunoblot analysis showed a high expression of bFGF in the treated retinas even 2 months after treatment. Illumination of P23H rats at P28 with 120 fc white light for 10 hours caused substantial photoreceptor cell death, although bFGF expression was upregulated. Lowered illumination dosages continued to cause photoreceptor damage until levels were reached that neither caused damage nor enhanced survival. CONCLUSIONS: Although light stress promotes photoreceptor survival and function in the RCS rat, it elicits death signals in the P23H rats that may not be overcome by survival-promoting factors. Therefore, use of light stress to promote photoreceptor survival should be considered with regard to sensitivity of the mutation to light damage.

Animals↗