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X Gong

Publications and source records attributed to X Gong.

At least 37 records · Page 2Linked to original sources
PubMed2000

Specificity determinants for the pyruvate dehydrogenase component reaction mapped with mutated and prosthetic group modified lipoyl domains.

Efficient catalysis in the second step of the pyruvate dehydrogenase (E1) component reaction requires a lipoyl group to be attached to a lipoyl domain that displays appropriately positioned specificity residues. As substrates, the human dihydrolipoyl acetyltransferase provides an N-terminal (L1) and an inner (L2) lipoyl domain. We evaluated the specificity requirements for the E1 reaction with 27 mutant L2 (including four substitutions for the lipoylated lysine, Lys(173)), with three analogs substituted for the lipoyl group on Lys(173), and with selected L1 mutants. Besides Lys(173) mutants, only E170Q mutation prevented lipoylation. Based on analysis of the structural stability of mutants by differential scanning calorimetry, alanine substitutions of residues with aromatic side chains in terminal regions outside the folded portion of the L2 domain significantly decreased the stability of mutant L2, suggesting specific interactions of these terminal regions with the folded domain. E1 reaction rates were markedly reduced by the following substitutions in the L2 domain (equivalent site-L1): L140A, S141A (S14A-L1), T143A, E162A, D172N, and E179A (E52A-L1). These mutants gave diverse changes in kinetic parameters. These residues are spread over >24 A on one side of the L2 structure, supporting extensive contact between E1 and L2 domain. Alignment of over 40 lipoyl domain sequences supports Ser(141), Thr(143), and Glu(179) serving as specificity residues for use by E1 from eukaryotic sources. Extensive interactions of the lipoyl-lysine prosthetic group within the active site are supported by the limited inhibition of E1 acetylation of native L2 by L2 domains altered either by mutation of Lys(173) or enzymatic addition of lipoate analogs to Lys(173). Thus, efficient use by mammalian E1 of cognate lipoyl domains derives from unique surface residues with critical interactions contributed by the universal lipoyl-lysine prosthetic group, key specificity residues, and some conserved residues, particularly Asp(172) adjacent to Lys(173).

Animals↗
PubMed2000

Genetic typing and HIV-1 diagnosis by using 96 capillary array electrophoresis and ultraviolet absorption detection.

Current high-throughput approaches to the analysis of PCR products are based primarily on electrophoretic separation and laser-excited fluorescence detection. We show that capillary array electrophoresis can be applied to HIV-1 diagnosis and D1S80 VNTR genetic typing based simply on UV absorption detection. The additive contribution of each base pair to the total absorption signal provides adequate detection sensitivity for analyzing most PCR products. Not only is the use of specialized and potentially toxic fluorescent labels eliminated, but also the complexity and cost of the instrumentation are greatly reduced.

Electrophoresis, Capillary↗
PubMed2000

Lop12, a mutation in mouse Crygd causing lens opacity similar to human Coppock cataract.

A new cataract mutation was discovered in an ongoing program to identify new mouse models of hereditary eye disease. Lens opacity 12 (Lop12) is a semidominant mutation that results in an irregular nuclear lens opacity similar to the human Coppock cataract. Lop12 is associated with a small nonrecombining segment that maps to mouse Chromosome 1 close to the eye lens obsolescence mutation (Cryge(Cat2-Elo)), a member of the gamma-crystallin gene cluster (Cryg). Using a systemic candidate gene approach to analyze the entire Cryg cluster, a G to A transition was found in exon 3 of Crygd associated with the Lop12 mutation and has been designated Crygd(Lop12). The mutation Crygd(Lop12) leads to the formation of an in-frame stop codon that produces a truncated protein of 156 amino acids. It is predicted that the defective gene product alters protein folding of the gamma-crystallin(s) and results in lens opacity.

Animals↗
PubMed2000

Characterization and gene structure of a novel retinoblastoma-protein-associated protein similar to the transcription regulator TFII-I.

Retinoblastoma protein (Rb) is an important regulator of vertebrate cell cycle and development. It functions through a direct interaction with protein factors involved in cell cycle progression and differentiation. In the present study we characterized a novel Rb-associated protein, Cream1, which bound to Rb specifically through a C-terminal region. Cream1 contained 959 amino acid residues and migrated as a protein of approx. 120 kDa on SDS/PAGE. It was a widely expressed nuclear protein with a nuclear localization signal resembling that of the large T antigen of simian virus 40. Its primary sequence was characteristic of five direct repeats that were similar to, but distinct from, those of TFII-I, a multifunctional transcription regulator. Three additional regions were also highly conserved in both proteins. Cream1 exhibited an activation activity that was attributed to its N-terminal portion when assayed in yeast. Its relationship with the muscle-enhancer-binding protein MusTRD1 further suggests a role in regulating gene expression. The structural gene, CREAM1, contained 27 exons and spanned more than 150 kb. It was located at human chromosome 7q11.23 in a region deleted for Williams' syndrome, a neurodevelopmental disease with multisystem abnormalities, implying its involvement in certain disorders. Taken together, our results suggest that Cream1 might serve as a positive transcription regulator under the control of Rb.

Amino Acid Sequence↗
PubMed2000

Mooren's ulcer in China: a study of clinical characteristics and treatment.

AIMS: To investigate the clinical characteristics and compare the effects of several methods of treatment of Mooren's corneal ulcer. METHODS: 550 consecutive cases of Mooren's corneal ulcer were analysed in patients, including age, sex, laterality of eye, ulcer location, perforative rate, cure rate of surgeries, recurrent rate, the effects of conjunctiva excision, lamellar keratoplasty (LKP), and LKP plus 1% cyclosporin A eye drops. RESULTS: The average age of onset was 48.4 years of age. The ratio of males to females was 1:0. 74. 165 (30%) cases had the disease bilaterally, of which 52 (31.5%) occurred in the young age group and 113 (68.5%) in the old age group. Ulcers of 501 eyes (70.1%) were located at the limbus of the palpebral fissure. The perforation rate was 13.3%, with perforation of 41 eyes (43.2%) occurring in the young age group and 54 (56.8%) in the old age group. Postoperative recurrence rate was 25.6%. The cure rate of the first procedure of LKP plus 1% cyclosporin A eye drops was 73.7%. The final cure rate was 95.6%, and the postoperative preservation rate of the eye globe was 99.7%. CONCLUSION: This primary study provided the clinical characteristics of patients with Mooren's corneal ulcer in China. LKP plus 1% cyclosporin A eye drops was an effective treatment.

Administration, Topical↗
PubMed2000

Erhaia (Gastropoda: Rissooidea): phylogenetic relationships and the question of Paragonimus coevolution in Asia.

The human lung fluke Paragonimus is transmitted by gastropod taxa of two superfamilies: Ceritheoidea and Rissooidea. The question whether or not Paragonimus shows the same specificity of host-parasite coevolved relationship as the human blood fluke Schistosoma was inspired by the finding of two sympatric snail species as hosts for Paragonimus skrjabini in Fujian Province, China: Gammatricula and Erhaia. The former species can clearly be classified as Pomatiopsidae: Triculinae. The latter has previously been classified as Pomatiopsidae: Pomatiopsinae. However, this classification based on anatomical characteristics is uncertain. In order to obtain a robust phylogenetic hypothesis for Erhaia, we have studied three gene fragments from this taxon as well as from twelve related taxa. The data show that the species involved represent four families: Pomatiopsidae, Hydrobiidae, Cochliopidae (here raised to family status), and Amnicolidae. Erhaia fits securely into the Amnicolidae. This indicates that P. skrjabini has not coevolved with snail lineages. However, P. skrjabini has so far only been reported from rissooidean snails, whereas members of the Paragonimus westermani complex have only been found in ceritheoidean snails. The implication is that there is a host specificity on the superfamily level. However, Asian freshwater species of the Ceritheoidea and Rissooidea usually are not sympatric and often prefer different habitats. It is therefore possible that ecological niche partitioning plays the primary role for Paragonimus evolution.

Animals↗
PubMed2000

[Tumor infiltrating dendritic cells in relation to prognosis of lung cancer].

OBJECTIVE: To study the degree of infiltration of dendritic cells in lung cancer in relation to prognosis. METHODS: S-100 protein as the marker of tumor-infiltraing dendritic cells (TIDC) was stained immunohistochemically in lung cancer specimens. The degree of infiltration was considered mild and marked according to the criteria reported by Furukawa. The survival rate was obtained by Log-rank test of the data. RESULTS: In 15 of 38 adenocarcinomas, whose TIDC infiltration was marked, the five-year survival rate was 60.0%, while in 23 with mild TIDC infiltration, the five-year survival rate was 21.7% (P < 0.01) Quite similar data were obtained from 44 squamous-cell carcinomas. Significantly higher five-year survival rate (61.1%) was observed in those with marked TIDC than those with mild infiltration (19.2%). CONCLUSION: The degree of TIDC infiltration is positively correlated with the survival rate of lung carcinoma patients.

Dendritic Cells↗
PubMed2000

[Dendritic cell infiltration in lung adenocarcinoma and its effect on prognosis].

OBJECTIVE: To study the infiltration degree of dendritic cells in lung adenocarcinoma and its effect on prognosis. METHODS: S-100 protein was used as the specific marker for dendritic cells, and immunohistochemistry was employed to detect the distribution of dendritic cells in lung adenocarcinoma. RESULTS: Among 46 cases of lung adenocarcinoma, 19 were markedly infiltrated by dendritic cells, the five-year survival rate being 61%; 27 showed slight infiltration, the five-year survival rate being 21%. Among the 46 cases of adenocarcinoma, 26 were low differentiated adenocarcinoma, in which 10 were infiltrated markedly by dendritic cells, five-year survival rate being 57%; and 16 were slightly infiltrated, five-year survival rate being 16%. These data were evaluated with the log-rank test, which showed a significant difference between the markedly infiltrated group and the slightly infiltrated group. CONCLUSION: The prognosis of lung adenocarcinoma which markedly infiltrated by dendritic cells is better than that of slightly infiltrated by dendritic cells.

Adenocarcinoma↗
PubMed2000

Microsurgical treatment of Mooren's ulcer.

OBJECTIVE: To evaluate effect of microsurgery of lamellar keratoplasty (LKP) on Mooren's corneal ulcer. METHODS: The effect, postoperative astigmatism, postoperative vision, ulcer recurrence of postoperation, and surgical complications of two groups of consecutive Mooren's ulcer inpatients treated respectively by non-microsurgery of LKP and microsurgery of LKP were analyzed. RESULTS: There were significant differences of the effect, postoperative astigmatism, postoperative vision, ulcer recurrence of postoperation, and surgical complications between the two groups. The effect and postoperative vision of the microsurgery-treated group were better than those of the non-microsurgery-treated group. The postoperative astigmatism, ulcer recurrence of postoperation, and surgical complications of the microsurgery-treated group were less than those of the nonmicrosurgery-treated group. CONCLUSION: Microsurgery of LKP of Mooren's corneal ulcer can greatly improve the ulcer healing and postoperative vision, and reduce the surgical complication and the ulcer recurrence of postoperation.

Adolescent↗
PubMed2000

[The analysis of the axises of corneal astigmatism and total astigmatism in astigmatic patients].

PURPOSE: The axial amount and the relationship between the axises of corneal astigmatism and total astigmatism were statistically analyzed in ametropic patients, for the purpose of selecting the refractive correction, the base curve of contact lens, the axis of astigmatic contact lens, and providing the reference of operational amount of ecimer laser keratoplasty. METHODS: The refractive state and the corneal curvature of ametropic patients were measured and consecutvely repeated 3 times in the same eye at the same state with the same autorefractometer in 107 cases. The detected axises of total astigmatism and corneal astigmatism were statistically analyzed through the computerized recording. RESULTS: The mean angle between the axis of corneal astigmatism and the axis of total astigmatism was 5.73 degrees +/- 3.97 degrees in myopic patients, 3.13 degrees +/- 2.49 degrees in mixture astigmatism patients and 6.35 degrees +/- 4.20 degrees in hyperopic patients. CONCLUSION: The angle between the axis of corneal astigmatism and the axis of total astigmatism in the refractive state was mainly caused by the difference of the axises of surface astigmatism of lens and cornea.

Adolescent↗
PubMed1999

Ribozyme-mediated down-regulation of ErbB-4 in estrogen receptor-positive breast cancer cells inhibits proliferation both in vitro and in vivo.

ErbB-4 is a recently discovered member of the class I receptor tyrosine kinase family (ErbB). Little is known about its expression and its importance in human malignancy. To delineate the biological function of ErbB-4 receptors in breast cancer, we used a hammerhead ribozyme strategy to achieve down-regulation of ErbB-4 receptors in various breast cancer cell lines. We observed that down-regulation of ErbB-4 in estrogen receptor-positive (ER+) human breast cancer cell lines (MCF-7 and T47D), which express relatively high levels of ErbB-4, significantly inhibited colony formation. No effects were observed in estrogen receptor-negative (ER-) MDA-MB-453 cells, which express low levels of endogenous ErbB4 and high levels of ErbB-2 and ErbB-3. This occurred despite the fact that fluorescence-activated cell sorter analysis of these latter cells revealed that the expression of the ErbB-4 receptor was completely abrogated by ribozyme treatment. Furthermore, down-regulation of ErbB-4 in T47D and MCF-7 cells significantly inhibited tumor formation in athymic nude mice (P < 0.03 and P < 0.001, respectively). In addition, NRG-stimulated phosphorylation of ErbB-4- and NRG-induced colony formation was significantly reduced in ribozyme-transfected T47D cells. These data provide the first evidence that elevation of ErbB-4 expression plays a role in the proliferation of some ER+ human breast cancer cell lines (T47D and MCF-7) that express high levels of ErbB-4. We have also investigated the expression of ErbB-4 in human primary breast carcinoma specimens, using immunohistochemical staining with an anti-ErbB-4 monoclonal antibody. ErbB-4 expression was found in 60% of the 50 primary breast tumors examined, and high intense immunoreactivity of ErbB-4 was detected in 18% of these primary breast tumors. ErbB-4 receptor expression appeared to correlate with ER+ primary breast tumors. A similar correlation was also observed in the human breast cancer cell lines. These results provide a better understanding of the biological significance of ErbB-4 receptor in breast cancer. Our data suggest that elevation of the ErbB-4 receptor plays a role in ER+ breast cancer cell proliferation. Moreover, ribozyme technology provides a useful tool to delineate the role of a particular gene product.

Animals↗
PubMed1999

Neurite outgrowth in PC12 cells. Distinguishing the roles of ubiquitylation and ubiquitin-dependent proteolysis.

Nerve growth factor (NGF)-induced neurite outgrowth from rat PC12 cells was coincident with elevated (>/=2-fold) levels of endogenous ubiquitin (Ub) protein conjugates, elevated rates of formation of 125I-labeled Ub approximately E1 (Ub-activating enzyme) thiol esters and 125I-labeled Ub approximately E2 (Ub carrier protein) thiol esters in vitro, and enhanced capacity to synthesize 125I-labeled Ub-protein conjugates de novo. Activities of at least four E2s were increased in NGF-treated cells, including E2(14K), a component of the N-end rule pathway. Ubiquitylation of 125 I-labeled beta-lactoglobulin was up to 4-fold greater in supernatants from NGF-treated cells versus untreated cells and was selectively inhibited by the dipeptide Leu-Ala, an inhibitor of Ub isopeptide ligase (E3). However, Ub-dependent proteolysis of 125I-labeled beta-lactoglobulin was not increased in supernatants from NGF-treated cells, suggesting that neurite outgrowth is promoted by enhanced rates of synthesis (rather than degradation) of Ub-protein conjugates. Consistent with this observation, neurite outgrowth was induced by proteasome inhibitors (lactacystin and clasto-lactacystin beta-lactone) and was associated with elevated levels of ubiquitylated protein and stabilization of the Ub-dependent substrate, p53. Lactacystin-induced neurite outgrowth was blocked by the dipeptide Leu-Ala (2 mM) but not by His-Ala. These data 1) demonstrate that the enhanced pool of ubiquitylated protein observed during neuritogenesis in PC12 cells reflects coordinated up-regulation of Ub-conjugating activity, 2) suggest that Ub-dependent proteolysis is a negative regulator of neurite outgrowth in vitro, and 3) support a role for E2(14K)/E3-mediated protein ubiquitylation in PC12 cell neurite outgrowth.

Animals↗
PubMed1999

Genetic factors influence cataract formation in alpha 3 connexin knockout mice.

Connexin alpha 3 (Cx46 or Gja3) gene targeted null mice developed lens nuclear cataracts shortly after birth. A large variance in the cataracts was observed in alpha 3 null sibs on a mixed 129SvJae X C57BL/6J F3 background. This suggested that the genetic background might influence the cataract phenotype. Therefore, we placed the alpha 3 null mutation into a 129SvJae background, and also backcrossed the mutation for six generations into 129SvJ and C57BL/6J backgrounds. While alpha 3 nulls on the two 129 backgrounds contained severe cataracts associated with gamma crystallin cleavage, alpha 3 nulls on the C57B16 background had far milder cataracts with no detectable gamma crystallin cleavage. These findings suggest that a genetic modifier exists that influences gamma crystallin stability, and that gamma crystallin breakdown is associated with severe nuclear cataracts.

Animals↗
PubMed1999

Ubiquitin-dependent pathway is up-regulated in differentiating lens cells.

The mammalian eye lens is composed of two distinct types of cells, epithelial cells and fiber cells. The fiber cells are generated throughout life via continuous differentiation of epithelial cells. Differentiation of lens cells involves dramatic changes in cellular components including altered activity of the ubiquitin dependent pathway. The concentration of high mass ubiquitin conjugates in the mitotically active-, differentiating-equatorial epithelial cells was 5-10 fold higher than that observed in mitotically quiescent, non-differentiated, central epithelial cells, even though there was a significant dilution of non-crystallin proteins due to an increase in level of crystallins in the differentiating cells. Similar observations were made when differentiation was modeled by exposure of lens epithelial explants to bFGF in culture. Activities of ubiquitin-activating enzyme (E1) and ubiquitin-conjugating enzymes (E2s) in the differentiating equatorial epithelial cells were also up to 100% higher than those noted in non-differentiated central epithelial cells and E1 appears to be rate controlling for ubiquitinylation. Consistent with the higher concentrations of high mass ubiquitin conjugates, there was a trend of enhanced ability to execute ATP-dependent protein degradation in the differentiating equatorial epithelial cells as compared with degradation in the non-differentiated central epithelial cells. These data indicate that the ubiquitin dependent pathway is up-regulated during differentiation of lens cells. In the differentiated fibers, the concentration of high mass ubiquitin conjugates and relative activities of E1 and E2s were 50% lower than in the non-differentiated central epithelial cells. In comparison, the concentration of the 110 kDa E1 was unchanged in differentiated fibers. However, if the factor of dilution by the significant increase in the level of crystallins was taken into account, the level or activities of the components of ubiquitin pathway in the differentiated cells was higher than the level noted in non-differentiated cells. These data indicate that, as compared with other non-crystallin proteins, there is differential stabilization and/or synthesis of the 110 kDa E1 and some other components of the ubiquitin dependent pathway in differentiated fibers.

Animals↗
PubMed1999

Stroke therapy in traditional Chinese medicine (TCM): prospects for drug discovery and development.

Brain injuries resulting from stroke are a major and increasing public health problem in both developed and developing countries worldwide. China's extensive experience in the use of traditional Chinese medicines (TCMs) in stroke therapy indicates that TCM preparations are effective, with few or no side-effects. There are more than 100 traditional medicines in use for stroke therapy in China. Some of their therapeutic effects in stroke have been confirmed by recent clinical studies. A large number of compounds have been isolated from TCMs and most of these resources have not yet been characterized for pharmacological purposes. Here, this article explains how TCM provides an extensive and knowledge-rich foundation for implementing a strategically focused pharmacological research programme aimed at the development of new drugs.

Anti-Inflammatory Agents↗
PubMed1999

Dynamics and stability analysis of the growth and astaxanthin production system of Haematococcus pluvialis.

This paper investigated high cell density cultivation of Haematococcus pluvialis for astaxanthin production in 3.7-L bioreactors. A biomass concentration of 2.74 g L-1and an astaxanthin yield of 64.4 mg L-1 were obtained. Based on the experimental results, a new and simple dynamic model is proposed, differing from Monod kinetics, to describe cell growth, product formation and substrate consumption. Good agreement was found between the model predictions and experimental data. The model revealed that there was cell growth inhibition on product formation and product feedback compensation for substrate consumption, but no substrate inhibition or product inhibition of cell growth. Stability analysis demonstrated that no multiplicity of steady states was observed; the unique positive steady state was locally asymptotically stable; and the effect of dilution rate on steady states was greater than that of the initial substrate concentration.

Journal Article↗
PubMed1999

In vivo hemodynamic evaluation based on transverse Doppler measurements of blood velocities and vessel diameter.

We have developed a method for simultaneously measuring the blood flow velocity distributions along a line perpendicular to the vessel wall and the instantaneous diameter of the common carotid artery. Thus, the wall shear rates and shear rate distribution across the arterial lumen could be computed accurately. In this method, transverse Doppler technique is combined with ultrasonic A echo-mode, using only one single crystal transducer. In order to satisfy the requirements of high spatial and velocity resolutions, especially extending to a very low velocity range in the case of low signal-to-noise ratio, a combination scheme of 10-MHz operating frequency, sample volume tracking, 12-bit A/D, 512-point fast Fourier transform with 5-kHz sample rate, spectrum average, variable threshold for bandwidth estimation, smoothing of velocity curves, and hardware was carefully designed. The velocity distribution measurements based on transverse Doppler spectrums were also validated under the steady flow conditions using a flow loop system. Results from this study show this ultrasonic system to be capable of measuring the shear rates at wall accurately and shear rate distributions across the common carotid arterial lumen.

Adult↗