Biomedical subjects

Yun Liu

Publications and source records attributed to Yun Liu.

At least 91 records · Page 5Linked to original sources

PubMed2004

Neuregulin-2 is developmentally regulated and targeted to dendrites of central neurons.

Neuregulin-1 (NRG-1) regulates numerous aspects of neural development and synaptic plasticity; the functions of NRG-2 and NRG-3 are presently unknown. As a first step toward understanding how NRGs contribute to distinct aspects of neural development and function, we characterized their regional and subcellular expression patterns in developing brain. The expression of NRG-1-3 mRNAs was compared postnatally (P0, P7, adult) by using in situ hybridization. NRG-1 expression is highest at birth, whereas NRG-2 mRNA levels increase with development; expression of both genes is restricted to distinct brain regions. In contrast, NRG-3 transcripts are abundant in most brain regions throughout development. NRG-2 antibodies were generated to analyze protein processing, expression, and subcellular distribution. As with NRG-1, the transmembrane NRG-2 proprotein is proteolytically processed in transfected HEK 293 cells and in neural tissues, and its ectodomain is exposed and accumulates on the neuron surface. Despite the structural similarities between NRG-1 and NRG-2, we unexpectedly found that NRG-2 colocalizes with MAP2 in proximal primary dendrites of hippocampal neurons in culture and in vivo, although it is not detectable in axons or in axon terminals. These findings were confirmed with NRG-2 ectodomain antisera and epitope-tagged recombinant protein. In cerebellum, NRG-2 colocalizes with calbindin in proximal dendrites and soma of Purkinje cells. In contrast, NRG-1 is highly expressed in axons of dissociated hippocampal neurons, as well as in somas and dendrites. The distinct temporal, regional, and subcellular expression of NRG-2 suggests its unique and nonredundant role in neural function.

Animals↗

PubMed2004

Safety and efficacy of dose-intensive oral vitamin A in subjects with sun-damaged skin.

PURPOSE: Previously, we reported the results of a Phase III, placebo-controlled trial in 2297 randomized participants with moderately severe actinic keratoses wherein 25000 IU/day vitamin A caused a 32% risk reduction in squamous cell skin cancers. We hypothesized that dose escalation of vitamin A to 50000 or 75000 IU/day would be both safe and more efficacious in skin cancer chemoprevention. EXPERIMENTAL DESIGN: One hundred and twenty-nine participants with severely sun-damaged skin on their lateral forearms were randomized to receive placebo or 25000, 50000, or 75000 IU/day vitamin A for 12 months. The primary study end points were the clinical and laboratory safety of vitamin A, and the secondary end points included quantitative, karyometric image analysis and assessment of retinoid and rexinoid receptors in sun-damaged skin. RESULTS: There were no significant differences in expected clinical and laboratory toxicities between the groups of participants randomized to placebo, 25000 IU/day, 50000 IU/day, and 75000 IU/day. Karyometric features were computed from the basal cell layer of skin biopsies, and a total of 22600 nuclei from 113 participants were examined, showing statistically significant, dose-response effects for vitamin A at the 25000 and 50000 IU/day doses. These karyometric changes correlated with increases in retinoic acid receptor alpha, retinoic acid receptor beta, and retinoid X receptor alpha at the 50000 IU/day vitamin A dose. CONCLUSIONS: The vitamin A doses of 50000 and 75000 IU/day for 1 year proved safe and equally more efficacious than the 25000 IU/day dose and can be recommended for future skin cancer chemoprevention studies.

Administration, Oral↗

PubMed2004

Calculation of 19F and 27Al NMR parameters for rosenbergite, AlF[F0.5(H2O)0.5]4.H2O, a possible model for Al hydroxyfluorides in solution.

(19)F and (27)Al NMR chemical shifts are calculated for the F and Al atoms of the mineral rosenbergite, AlF[F(0.5)(H(2)O)(0.5)](4).H(2)O The structure of rosenbergite consists of infinite chains of F-corner-sharing Al[F(4)(H(2)O)(2)] octahedra and isolated water molecules. An F-centered molecular cluster of composition Al(2)F(3)(OH(2))(8) (3+) was initially used to model the mineral, with geometries taken both from the two different available x-ray crystal structures and from equilibrium geometries calculated at the 6-31G* B3LYP level (both with and without polarizable continuum solvation). Related Al(F)F(n) em leader clusters, with additional F(-) replacing H(2)O, were also studied. A larger Al-centered cluster model Al(3)F(4)(OH(2))(12) (5+) was also generated from one of the x-ray geometries and produced very similar bridging F shieldings but slightly different Al shieldings. The NMR shieldings were calculated using both HF and B3LYP GIAO methods, with 6-311+G(2df,p) basis sets, and the HF and B3LYP results averaged for the F shieldings as described in previous work. Calculated (19)F NMR shifts (relative to CCl(3)F) using this procedure were within a few ppm of experiment when either set of x-ray crystal structure coordinates was used, but differed by as much as 20 ppm for the energy-optimized geometries. Rosenbergite-like fragments with geometries optimized in water, simulated by a PCM, were used to model Al hydroxyfluoride species in solution. The (19)F NMR shifts for the bridging F atoms in several such model complexes are very similar to those usually attributed to monomeric species such as Al(OH(2))(5)F(2+) in solution, suggesting that the solution species are actually corner bridging oligomers. The F in the monomeric Al(OH(2))(5)F(2+) solution species is too strongly shielded by about 20 ppm to match the experimental peak usually assigned to it.

Journal Article↗

PubMed2004

The development of the lymphoid organs of flounder, Paralichthys olivaceus, from hatching to 13 months.

The growth of the lymphoid organs, such as head kidney, spleen and thymus were studied in flounder, Paralichthys olivaceus Temminck & Schlegel, from hatching to 13 months of age. Except for the thymus, all organs grew as the fish grew. By 2 months of age the lymphoid organs attained their maximum relative weight. The organ weight showed a closer correlation to body weight than they did to age. The total number of leucocytes in the lymphoid organs increased with age, but the number per milligram of lymphoid organ remained constant. A micro and ultrastructural study of the lymphoid organs showed that the full development of the lymphoid organs was not achieved until the juvenile stage. The spleen and head kidney had mixed populations of "red" and "white" cells. The head kidney was more lymphoid than the spleen. The thymus involuted quickly during the first 6 months. The blood components had no obvious relationship with age or season during the period studied.

Age Factors↗

PubMed2004

Comparative and evolutionary analysis of the cytochrome b sequences in cyprinids with different ploidy levels derived from crosses.

The mitochondrial cyt b genes in the allotetraploid and triploid crucian carp as well as triploid common carp were isolated and completely sequenced. Their DNA sequences were compared with those derived from the cyt b genes of the red crucian carp, Japanese crucian carp, and common carp with MEGA 1.0 software. Phylogenetic analysis revealed the sister relationships between allotetraploid and diploid red crucian carp, between the triploid crucian carp and diploid Japanese crucian carp, and between triploid common carp and diploid common carp. Our results indicated the cyt b genes in the allotetraploid, triploid crucian carp, and triploid common carp were maternally inherited. Through maternal inheritance, the cyt b gene in the F11 tetraploid displayed extremely high similarity to that in the female parent red crucian carp after 11 generations (from F1 to F11 hybrids). Since the establishment of the new tetraploid stocks has great significance in analyzing evolutionary theory of vertebrate and in improving aquaculture industry, analysis of the cyt b gene and the elucidation of the variation of the cyt b gene DNA in different cyprinids prove that cyt b is a useful genetic marker to monitor the variations in the progeny of the crosses.

Amino Acid Sequence↗

PubMed2004

Review of the pharmacological and clinical profile of rimcazole.

Rimcazole is a carbazole derivative that acts in part as a sigma receptor antagonist. Wellcome Research Laboratories introduced this compound during the 1980s when it was hypothesized to be a novel antipsychotic with an improved side effect profile. However, subsequent clinical trials demonstrated that rimcazole lacked efficacy in schizophrenic patients and it is now primarily used as an experimental tool. In addition to its actions as a sigma receptor antagonist, rimcazole also has high affinity for dopamine transporters, and in recent years it has served as a lead compound for the development of novel dopamine transporter ligands. Although rimcazole cannot be considered a selective ligand for sigma receptors, the recent development of other selective agonists and antagonists for sigma receptors have aided in clarifying the involvement of these receptors in the actions of rimcazole. Many of the physiological and behavioral effects of rimcazole can in fact be ascribed to its action as a sigma receptor antagonist, although there are exceptions. Rimcazole is likely to have a continued role in elucidating sigma receptor function in either in vitro or in vivo systems where sigma receptor-mediated effects can be studied independently of the influence of dopamine and serotonin transporters.

Animals↗

PubMed2004

Human papillomavirus type 16 E6 amino acid 83 variants enhance E6-mediated MAPK signaling and differentially regulate tumorigenesis by notch signaling and oncogenic Ras.

Oncogenically high-risk human papillomaviruses (HPVs) are causally associated with the progression of major human neoplasia-like cancers of the cervix. Several studies have defined functions of the key E6 and E7 oncoproteins in epithelial cell immortalization. The roles of these oncogenes in the progression of immortalized epithelial cells to invasive tumors are still poorly understood. Here, we establish a novel link between the E6 oncoprotein and activation of mitogen-activated protein kinase (MAPK) signaling and show that this signaling involves Rap1. We find that activated MAPK signaling cooperates with deregulated Notch1 signaling to recreate features of HPV-driven invasive cervical carcinomas. We extend our analysis to evaluate an E6 (amino acid [aa] 83) variant that has been linked to invasive tumors. The variant enhances MAPK signaling and cooperative transformation with deregulated Notch1 signaling. Unlike E6, this variant surprisingly inhibits oncogenic Ras-mediated transformation. Our data reveal that the quantitative differences in activation of MAPK signaling by E6 and its variant correlate with differences in cooperative transformation with other signaling pathways, thus suggesting that thresholds of MAPK activation may define permissive conditions for other signaling pathways in tumorigenesis. Epidemiological studies have suggested the importance of E6 aa 83 variants in invasive carcinomas; our data support a key deterministic role for this variant in human cervical tumorigenesis. These observations, along with our recent data showing that deregulated Notch signaling activates phosphatidylinositol 3-kinase signaling, strengthen the possibility of the existence of Ras-independent mechanisms to recreate signaling through classical Ras effector pathways.

Animals↗

PubMed2004

Synthesis of titanate nanofibers and nanotubes.

A simple, mild and low-cost refluxing method was successfully used to synthesize titanate nanofibers and nanotubes. Properties of the as-prepared samples were characterized by means of TEM and XRD techniques. Optimization of the experimental conditions allowed, respectively, the preparation of titanate nanofibers and nanotubes. The photocatalytic activities of the prepared products were also investigated. The results indicated that titanate nanofibers and nanotubes had no photocatalytic activities for the degradation of methyl orange. Calcined at different temperature, the photocatalytic activities of the products increased, accompanying the change of structures.

Catalysis↗

PubMed2004

[Fine needle aspiration cytology of eyelid sebaceous gland carcinoma and its differential diagnosis].

OBJECTIVE: To investigate the fine needle aspiration cytology (FNAC) features and differential diagnosis of eyelid sebaceous gland carcinoma. METHODS: Four cases of eyelid sebaceous gland carcinoma diagnosed by FNAC were reported and confirmed by biopsy. Three of the cases were in early stages with tumor sizes smaller than 10 mm in diameter and without metastasis. The smears were stained by routine H & E and SudanIII methods. The cytologic findings were described and compared to corresponding histological features, and moreover, compared to chalazion, pilomatrixoma and eyelid basal cell carcinoma. RESULTS: Neither hemorrhage nor infection were found after the examination. Abundant cells were observed in the sebaceous carcinoma FNAC smears. Two types of tumor cells were found: one showed tumor cells differentiating toward sebaceous gland, with large pale cells and vacuolated cytoplasm, the other demonstrated poorly-differentiated cell with dark and irregular nuclei. Numerous vacuoles with inequality of size were found in cytoplasm or in background in all four cases, and the SudanIII stain showed that these vacuoles contained lipid. Some smears demonstrated cells with basaloid, fusiform or squamous features, corresponding to various histopathological types. In contrast, smears of chalazion displayed inflammatory granuloma, containing several types of inflammatory cells without malignant cells. Smears of pilomatrixoma were cellular with three cell populations, which included bland sheets of basaloid cells, nucleated basophilic cells and anucleated keratinized "ghost cells", along with calcific debris. The smears of basal cell carcinoma were typically less cellular, more tightly cohesive and had smaller clusters of uniform hyperchromatic basaloid cells without vacuolization in cytoplasm or background. Overall, the cytological features of eyelid sebaceous carcinoma were distinct from those of chalazion, pilomatricoma and basal cell carcinoma. CONCLUSIONS: FNAC is a safe and effective approach for the diagnosis of eyelid sebaceous carcinoma and lipid stain is useful in differential diagnosis. The application of FNAC may be important in reaching an early diagnosis and initial treatment of eyelid nodule.

Adult↗

PubMed2004

[Temporal and spatial structure of carabid community in agricultural landscape of Dongbeiwang, Beijing].

From May to October 2000, the carabid beetles in the habitats of woodland, field margin and crop field in Dong-beiwang agroecosystem in Beijing were investigated by pitfall traps, and the temporal and spatial structure of carabid community was analyzed. The results indicated that the numbers of both carabid species and individuals were much higher in the field margin and woodland than in the crop field. Both dominant species and rare species tended to live in field margin and/or woodland. Field margins had a positive effect on the diversity and richness of carabid community in their adjacent crop fields. The modest disturbance (plowing in autumn) in the field margin was beneficial for the increase of the individual number of carabid community, and the treatments of irrigation, fertilization and straw return in field had no effects on both the individual and species number of carabid community. Furthermore, the threatening condition to some carabid species was discussed, based on the analysis of the temporal and spatial dynamics of carabid community.

Agriculture↗

PubMed2004

Karyometric image analysis for intraepithelial and invasive cervical lesions.

OBJECTIVE: To derive an objective, numeric measure for the progression of intraepithelial and invasive squamous cell cervical lesions. STUDY DESIGN: Thin-layer cervical cytology preparations from colposcopically confirmed normal cervix, low grade squamous intraepithelial lesions, high grade squamous intraepithelial lesions and carcinoma were identified from a cross-sectional study. Fifty-nine cases representing 4 diagnostic categories were selected, and 2,375 nuclei from epithelial cells representative of the diagnostic category were randomly selected for imaging and measurement from these cases. Additionally, 1,378 visually normal appearing intermediate cells from low and high grade squamous intraepithelial lesions, as well as from carcinoma cases, were identified for analysis. The nuclei were quantitatively characterized, and discriminant analyses were performed to derive a progression curve from normal cytology to carcinoma. RESULTS: The lesion signatures show a clear increase in nuclear abnormality with increasing progression. A progression curve was derived based on mean discriminant function scores for each diagnostic category and on the mean nuclear abnormality values for the nuclei in each category, as expressed by their deviation in feature values from normal reference nuclei. CONCLUSION: A numeric assessment of lesion progression for cervical precancerous and cancerous lesions based on karyometric measurements is possible and may provide an objective, precise characterization of each lesion as well as a basis for improved performance in automated cytology-based cervical cancer screening.

Cell Nucleus↗

PubMed2004

Karyometric analysis of actinic damage in unexposed and sun-exposed skin and in actinic keratoses in untreated individuals.

OBJECTIVE: To assess the ability of karyometric analysis to demonstrate progression of actinic damage as a function of sun exposure in individuals with actinic keratoses (AKs) and to evaluate the stability of that assessment over a 3-month period. STUDY DESIGN: Biopsies from subjects with AKs were obtained from unexposed skin, sun-exposed skin and AK lesions. Subjects used an SPF 50 sunscreen, and 3 months later additional biopsies were taken from sun-exposed and AK sites. A total of 13,300 nuclei were recorded from 31 subjects. RESULTS: Measures of nuclear abnormality (NA) and effects of sun damage based on discriminant function (DF) scores were derived. Actinic damage levels varied significantly across biopsy site, demonstrating the method's sensitivity. Accrual of actinic damage was demonstrated in sun-exposed skin and AK lesions when all nuclei were examined over 3 months but only for sun-exposed skin when the worst-damaged nuclei were examined. This suggests a ceiling effect of nuclear damage in the progression to abnormality. Within-subject variability was similar for both NA and DF when all nuclei were considered. Among the worst-damaged nuclei (as defined by high DF), DF showed lower within-case variability than NA, perhaps due to a reduction in nuclear heterogeneity. CONCLUSION: Karyometry's ability to detect subtle levels of actinic damage in nuclear chromatin patterns may make it useful in screening agents for possible use in cancer chemoprevention.

Actins↗

PubMed2004

[Analysis of Camellia rosthorniana populations fecundity].

With the method of space substituting time, the structure of Camellia rosthorniana populations in three forest communities, i.e., Jiant bamboo forest, coniferous and broad-leaved mixed forest, and evergreen broad-leaved forest in Mt. Jinyun was investigated, and based on static life-tables, the fecundity tables and reproductive value tables of C. rosthorniana populations were constructed. Each reproductive parameter and its relation to bionomic strategies of C. rosthorniana populations were also analyzed. The results indicated that in evergreen broad-leaved forest, C. rosthorniana population had the longest life span and the greatest fitness. The stage of maximum reproductive value increased with increasing stability of the community. The sum of each population's reproductive value, residual reproductive value and total reproductive value for the whole life-history of C. rosthorniana also increased with increasing maturity of the community, showing their inherent relationships with reproductive fitness. As regards to bionomic strategy, C. rosthorniana showed mainly the characteristics of a k-strategies, but in less stable community, the reproductive parameters were greatly changed, showing some characteristics of a r-strategies.

Camellia↗

PubMed2004

[Physiological and ecological effects of potassium on expansion of crocus corm].

The corm size of Crocus sativus, a well-known medicine, is a key limiting factor for its stigma harvest. A water cultural experiment with four different potassium (K) concentrations showed that the K content, chlorophyll content, relative ATP content and net photosynthetic rate in C. sativus leaves increased with improving K concentration, which enhanced the function of leaves to be metabolic source. On the other hand, the K absorbing ability and the contents of soluble sugars, vitamin C (Vc) and protein in new-born corms were increased with improving K concentration, which also strengthened the function of new-born corms to be metabolic sink. This study also showed that K could promote the new-born corm growth rate of C. sativus through strengthening the function of "source" and "sink".

Adenosine Triphosphate↗

PubMed2004

[Effect of different ecological factors on ricefield eel (Monopterus albus) hatching rate].

This paper studied the effects, of some ecological factors (temperature, pH, hatching method and ammonia) on the embryonic development of ricefield eel. The results indicated that the optimum hatching temperature of ricefield eel was 25-28 degrees C, and no significant difference was found about the effects of pH within the range of pH 5.5-9.5 on the hatching rate of oosperm. Dripping water incubation had a higher hatching rate of oosperm than staticing water incubation, and the hatching rate of oosperm decreased with increasing ammonia content. The present study provided an available suggestion for the all-artificial and half-artificial breeding of ricefield eel.

Ammonia↗

PubMed2004

Preneoplastic changes in ovarian tissues.

OBJECTIVE: To test whether histologically normal epithelium within ovarian inclusion cysts and stroma exhibit changes in nuclear chromatin pattern that indicate the presence of occult ovarian lesions. STUDY DESIGN: Ovaries were collected from 10 low-risk women,from 7 high-risk women and from 3 women with ovarian cancer. Histologic sections were cut at 5 microm and hematoxylin and eosin stained. High-resolution images were recorded from the epithelium lining inclusion cysts and from the underlying stroma of ovaries from these 20 subjects. A total of 2860 epithelial nuclei and 3610 stromal nuclei were recorded. Karyometric features and nuclear abnormality were computed. Discriminant analyses and unsupervised learning algorithms defined deviations from normal that were designated "above threshold" and used to compute average nuclear abnormality of a second nuclear phenotype. RESULTS: Histologically normal epithelium from inclusion cysts of ovaries harboring a malignant lesion was shown to exhibit changes in the nuclear chromatin pattern that were statistically significant using quantitative image analysis procedures. Similar changes were seen in the inclusion cyst epithelia of high-risk ovaries. A subpopulation of cells representing a new phenotype was detected in the underlying stroma of women harboring a malignant ovarian lesion and in women at high risk of ovarian cancer. CONCLUSION: The karyometric changes observed in the epithelia lining inclusion cysts and in the underlying stroma of ovaries either with ovarian cancer or at high risk of ovarian cancer suggest the presence of preneoplastic changes in histologically normal tissue.

Cell Nucleus↗

PubMed2004

[Triploid crucain carp-allotetraploid hybrids (male) x goldfish( hermaphrodite)].

A new type of triploid crucian carp was generated by mating the males of the allotetraploid hybrids of red crucian carp (Carassius auratus red var.) (female) x common carp (Cyprinus carpio L.) (male), with the females the goldfish( Carassius auratus red var.) which was red in color and possessed the biforked tails. The biological characteristics of one-year old triploid crucian carp including the number and karotype of chromosome, gonadosomatic indices and gonadal structures, appearance and growth rate were investigated. The results indicated that the triploid crucian carp possessed 150 chromosomes with the karyotype: 33m + 51sm + 33st + 33t. In the breeding season, the gonadosomatic indices (GSI) of the ovaries and testes in the triplpoid crcuian carp were, respectively, lower than those in the diploid red crucian carp, and the tissue sections showed that both the ovaries and the testes in the triploid cruican carp were not able to produce the mature ova and sperm, respectively, indicating that they were sterile during one year. The triploid crucian carp was gray in color and had a single fork tail. They had other morphological traits intermediate to the paternal allotetraploid hybrids and the maternal goldfish, for example, one pair of very short and not readily visible barbells, the formula of lateral line scales: 31-6/7, 18 dorsal fin spines, and 0.5 in ratio of the width to the length of the body which was evidently higher than that (0.41) in another kind of triploid crucian carp called Xiangyun crucian carp, generated by crossing the males of the allotetraploid hybrids with the females of the Japanese crucain carp (Carassius auratus cuvieri T. et S.). Following 8-month culture, the triploid crucian carp averagely reached 350 gram in which the maximum individual weighed 550 gram. Among one- year old triploid crucian carp, the females grew faster than the males. Compared with Xiangyun crucian carp, the new type of triploid crucian carp not only presented some advantages the Xiangyun crucian carp had, for example, fast growth rate and potential sterility, but also got some new good performances like the high ratio of the width to the length of the body and the sweet flesh, suggesting they will be very potential in the commercial interest.

Animals↗

PubMed2004

[New progresses on mitochondrial DNA in fish].

The study on mitochondrial DNA (mtDNA) is a hot field in recent molecular biology. With some special characteristics, mitochondrial DNA as an ideal genetic marker has been successfully applied to the research of population and evolutionary biology of fish. Many scientific achievements on mtDNA in fish have been made, however, a number of issues need to be further studied and explored. In the present paper, the research progresses on the complete mtDNA sequences, the structures and characteristics of mtDNA, the mtDNA control region structures, and mtDNA polymorphisms and detecting methods are introduced. Furthermore,we review the applications in the recent years in the fields of systematic evolution, hybridization and introgression, biogeography and population genetics of fish.

Animals↗