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Biomedical subjects

L Hu

Publications and source records attributed to L Hu.

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

Differences in the immunogenicity of latent membrane protein 1 (LMP1) encoded by Epstein-Barr virus genomes derived from LMP1-positive and -negative nasopharyngeal carcinoma.

We have previously shown that an EBV-encoded latent membrane protein 1 (LMP1) gene derived from a nude mouse-propagated nasopharyngeal carcinoma (NPC) tumor and expressed in nonimmunogenic murine mammary carcinoma S6C cells failed to convey immunogenicity (rejectability) in syngeneic mice, whereas the corresponding B-cell derived LMP1 gene made the mice highly immunogenic. This raised the question of whether LMPL-expressing NPCs have been selected for low immunogenicity at the viral gene expression level. If so, LMP1-negative tumors that carry highly methylated LMP1 regulatory sequences may not have been exposed to a similar immunoselection. In the present study, we have compared LMP1 genes derived from two LMP1-positive NPCs and two LMP1-negative NPCs. All four genes were expressed in S6C cells in parallel with the previously tested isolates from a B-cell (B95-8)-derived and a nude mouse-propagated NPC (Cao)-derived gene. As in the previous study, we have found that the B-cell-derived LMP1 isolate was highly immunogenic. LMP1-positive tumor-derived isolates were poorly immunogenic, whereas the isolates from the LMP1-negative NPC tumor had intermediate immunogenicity. Sequence data revealed that LMP1 genes from LMP1-expressing NPC had 16 amino acid substitutions, whereas LMP1 from non-LMP1-expressing NPC had only 9 amino acid changes in the coding region. Three of the changes were at shared sites, but with different modifications. The fact that the gene from non-LMP1-expressing NPC mutated at a low frequency but was more immunogenic than the LMP1 gene derived from LMP1-expressing NPC, which was highly mutated but less immunogenic, favors the idea that LMP1-positive tumors escape immunosurveillance in immunocompetent hosts by either a selective down-regulation of LMP1 expression, methylation in the LMP1 promoter sequence, or mutation of LMP1 in LMP1-expressing samples.

Animals↗
PubMed2000

Refinement of the locus for autosomal dominant hereditary gingival fibromatosis (GINGF) to a 3.8-cM region on 2p21.

Hereditary gingival fibromatosis (HGF, MIM 135300; approved gene symbol GINGF) is an oral disease characterized by enlargement of gingiva. Recently, a locus for autosomal dominant HGF has been mapped to an 11-cM region on chromosome 2p21. In the current investigation, we genotyped four Chinese HGF families using polymorphic microsatellite markers on 2p21. The HOMOG test provided evidence for genetic homogeneity, with evidence for linkage in four families (heterogeneity versus homogeneity test HOMOG, chi(2) = 0. 00). A cumulative maximum two-point lod score of 5.04 was produced with marker D2S390 at a recombination frequency of θ = 0 in the four linked families. Haplotype analysis localized the hereditary gingival fibromatosis locus within the region defined by D2S352 and D2S2163. This region overlaps by 3.8 cM with the previously reported HGF region. Single-strand conformation polymorphism and sequence analysis of the coding region of cytochrome P450 1B1 (CYP1B1) excluded it as a likely candidate gene.

Aryl Hydrocarbon Hydroxylases↗
PubMed2000

Genetic diversity and disease control in rice.

Crop heterogeneity is a possible solution to the vulnerability of monocultured crops to disease. Both theory and observation indicate that genetic heterogeneity provides greater disease suppression when used over large areas, though experimental data are lacking. Here we report a unique cooperation among farmers, researchers and extension personnel in Yunnan Province, China--genetically diversified rice crops were planted in all the rice fields in five townships in 1998 and ten townships in 1999. Control plots of monocultured crops allowed us to calculate the effect of diversity on the severity of rice blast, the major disease of rice. Disease-susceptible rice varieties planted in mixtures with resistant varieties had 89% greater yield and blast was 94% less severe than when they were grown in monoculture. The experiment was so successful that fungicidal sprays were no longer applied by the end of the two-year programme. Our results support the view that intraspecific crop diversification provides an ecological approach to disease control that can be highly effective over a large area and contribute to the sustainability of crop production.

Agriculture↗
PubMed2000

5'-[2-(2-Nitrophenyl)-2-methylpropionyl]-2'-deoxy-5-fluorouridine as a potential bioreductively activated prodrug of FUDR: synthesis, stability and reductive activation.

5'-[2-(2-Nitrophenyl)-2-methylpropionyl]-2'-deoxy-5-fluorouridine was synthesized as a potential bioreductively activated prodrug of 5-fluoro-2'-deoxyuridine (FUDR). The target compound was stable in both phosphate buffer and human serum and was found to release quickly the parent drug FUDR in quantitative yield upon mild chemical reduction.

Biological Availability↗
PubMed2000

Change of coagulation factor VIII and antithrombin III activity in bank-stored blood.

Coagulation factor VIII and antithrombin III activity were detected in 15 health donors. It was found that antithrombin III activity decreased obviously 12 h after blood drawing. It lost 56% of the activity at the 3rd day, and 70% of the activity at the 7th day. FVIII:c showed no obvious change after 24 h, until the 3rd day. It lost 40%-60% of the activity after 36 h and was reduced to the 30% of the original activity at the 5th day. Our results suggested that at the 3rd day coagulation factor VIII of bank-stored blood can be used to replenish antithrombin III, while bank-stored blood in one day can be used to replenish F VIII.

Adolescent↗
PubMed2000

Experiments on gene transferring to primary hematopoietic cells by liposome.

Liposomes have showed many advantages in mediating exogenous gene into many cell types in vitro and in vivo. But few data are available concerning gene transfer into hematopoietic cells. In this report, we described two-marker genes (Neo R and Lac Z) co-transferred into hematopoietic cells of human and mouse by using liposome in vitro. The efficiency of gene transfer was tested by X-gal staining and observation of colony formation. The X-gal blue staining rate of transduced cells was about (13.33 +/- 2.68)% in human and about (16.28 +/- 2.95)% in mouse without G418 selection. After G418 selection, the blue cell rate was (46.06 +/- 3.47)% in human and (43.45 +/- 4.1)% in mouse, which were markedly higher than those before selection, suggesting that high-efficiency gene transfer and expression could be attained in primary hematopoietic cells using this easy and harmless transduction protocol. At the same time, this protocol provided experimental data for clinicians to investigate the biology of marrow reconstitution and trace the origin of relapse after autologous bone marrow transplantation for the patients with leukemia.

Animals↗
PubMed2000

Vitamin A deficiency injures lung and liver parenchyma and impairs function of rat type II pneumocytes.

The purpose of this research was to determine the effects of vitamin A deficiency on liver and lung morphology and type II pneumocyte function. Weanling rats were fed a retinol-adequate (control) or -deficient diet for 6 wk. Average food intakes and body weights were not different between the vitamin A-deficient and -adequate rats. Histologic examination revealed that the lungs of vitamin A-deficient rats had less collagen in the adventitia of small caliber arteries and arterioles and in the alveolar septa, which appeared thinner than that of controls. Many areas of the lungs of the same rats were also emphysematous (increased size of air spaces distal to the terminal bronchiole, with thinning and partial or total destruction of septal wall). Content of elastin also was lower in the lung parenchyma, as well as in the small arteries and arterioles, but not in the larger ones. Peribronchial collagen was not affected by the deficient diet. Scattered inflammation was observed in most of the vitamin A-deficient rats; a mild inflammatory reaction also was seen in one of the controls. Vitamin A-deficient rats also exhibited hepatocyte vacuolization and mild inflammation in the liver, specifically in the periportal tracts. Surfactant synthesis and ornithine decarboxylase activity were significantly lower in type II pneumocytes isolated from vitamin A-deficient rats. In conclusion, our data provide evidence that vitamin A deficiency produces profound morphologic alterations in liver and lung parenchyma and impairs pneumocyte function.

Animals↗
PubMed2000

Differential bacterial survival, replication, and apoptosis-inducing ability of Salmonella serovars within human and murine macrophages.

Salmonella serovars are associated with human diseases that range from mild gastroenteritis to host-disseminated enteric fever. Human infections by Salmonella enterica serovar Typhi can lead to typhoid fever, but this serovar does not typically cause disease in mice or other animals. In contrast, S. enterica serovar Typhimurium and S. enterica serovar Enteritidis, which are usually linked to localized gastroenteritis in humans and some animal species, elicit a systemic infection in mice. To better understand these observations, multiple strains of each of several chosen serovars of Salmonella were tested for the ability in the nonopsonized state to enter, survive, and replicate within human macrophage cells (U937 and elutriated primary cells) compared with murine macrophage cells (J774A.1 and primary peritoneal cells); in addition, death of the infected macrophages was monitored. The serovar Typhimurium strains all demonstrated enhanced survival within J774A.1 cells and murine peritoneal macrophages, compared with the significant, almost 100-fold declines in viable counts noted for serovar Typhi strains. Viable counts for serovar Enteritidis either matched the level of serovar Typhi (J774A. 1 macrophages) or were comparable to counts for serovar Typhimurium (murine peritoneal macrophages). Apoptosis was significantly higher in J774A.1 cells infected with serovar Typhimurium strain LT2 compared to serovar Typhi strain Ty2. On the other hand, serovar Typhi survived at a level up to 100-fold higher in elutriated human macrophages and 2- to 3-fold higher in U937 cells compared to the serovar Typhimurium and Enteritidis strains tested. Despite the differential multiplication of serovar Typhi during infection of U937 cells, serovar Typhi caused significantly less apoptosis than infections with serovar Typhimurium. These observations indicate variability in intramacrophage survival and host cytotoxicity among the various serovars and are the first to show differences in the apoptotic response of distinct Salmonella serovars residing in human macrophage cells. These studies suggest that nonopsonized serovar Typhimurium enters, multiplies within, and causes considerable, acute death of macrophages, leading to a highly virulent infection in mice (resulting in death within 14 days). In striking contrast, nonopsonized serovar Typhi survives silently and chronically within human macrophages, causing little cell death, which allows for intrahost dissemination and typhoid fever (low host mortality). The type of disease associated with any particular serovar of Salmonella is linked to the ability of that serovar both to persist within and to elicit damage in a specific host's macrophage cells.

Animals↗
PubMed2000

Involvement of a plasmid in virulence of Campylobacter jejuni 81-176.

Campylobacter jejuni strain 81-176 contains two, previously undescribed plasmids, each of which is approximately 35 kb in size. Although one of the plasmids, termed pTet, carries a tetO gene, conjugative transfer of tetracycline resistance to another strain of C. jejuni could not be demonstrated. Partial sequence analysis of the second plasmid, pVir, revealed the presence of four open reading frames which encode proteins with significant sequence similarity to Helicobacter pylori proteins, including one encoded by the cag pathogenicity island. All four of these plasmid-encoded proteins show some level of homology to components of type IV secretion systems. Mutation of one of these plasmid genes, comB3, reduced both adherence to and invasion of INT407 cells to approximately one-third that seen with wild-type strain 81-176. Mutation of comB3 also reduced the natural transformation frequency. A mutation in a second plasmid gene, a virB11 homolog, resulted in a 6-fold reduction in adherence and an 11-fold reduction in invasion compared to the wild type. The isogenic virB11 mutant of strain 81-176 also demonstrated significantly reduced virulence in the ferret diarrheal disease model. The virB11 homolog was detected on plasmids in 6 out of 58 fresh clinical isolates of C. jejuni, suggesting that plasmids are involved in the virulence of a subset of C. jejuni pathogens.

Animals↗
PubMed2000

Cpc2, a fission yeast homologue of mammalian RACK1 protein, interacts with Ran1 (Pat1) kinase To regulate cell cycle progression and meiotic development.

The Schizosaccharomyces pombe ran1/pat1 gene regulates the transition between mitosis and meiosis. Inactivation of Ran1 (Pat1) kinase is necessary and sufficient for cells to exit the cell cycle and undergo meiosis. The yeast two-hybrid interaction trap was used to identify protein partners for Ran1/Pat1. Here we report the identification of one of these, Cpc2. Cpc2 encodes a homologue of RACK1, a WD protein with homology to the beta subunit of heterotrimeric G proteins. RACK1 is a highly conserved protein, although its function remains undefined. In mammalian cells, RACK1 physically associates with some signal transduction proteins, including Src and protein kinase C. Fission yeast cells containing a cpc2 null allele are viable but cell cycle delayed. cpc2Delta cells fail to accumulate in G(1) when starved of nitrogen. This leads to defects in conjugation and meiosis. Copurification studies show that although Cpc2 and Ran1 (Pat1) physically associate, Cpc2 does not alter Ran1 (Pat1) kinase activity in vitro. Using a Ran1 (Pat1) fusion to green fluorescent protein, we show that localization of the kinase is impaired in cpc2Delta cells. Thus, in parallel with the proposed role of RACK1 in mammalian cells, fission yeast cpc2 may function as an anchoring protein for Ran1 (Pat1) kinase. All defects associated with loss of cpc2 are reversed in cells expressing mammalian RACK1, demonstrating that the fission yeast and mammalian gene products are indeed functional homologues.

Amino Acid Sequence↗
PubMed2000

In vivo and in vitro ovarian carcinoma growth inhibition by a phosphatidylinositol 3-kinase inhibitor (LY294002).

Phosphatidylinositol 3-kinase (PI3-K) induces mitogenesis, cell growth, and cell transformation. Amplification of the gene encoding the P110alpha subunit likely is an important event in ovarian cancer progression, and PI3-K inhibitors are possible therapeutic agents for this disease. We evaluated effects of LY294002, a potent inhibitor of PI3-K, on growth of ovarian carcinoma in vivo and in vitro, and on ascites formation in vivo. Athymic mice were inoculated i.p. with the ovarian cancer cell line OVCAR-3. Seven days after inoculation, mice were treated with or without LY294002 (100 mg/kg of body weight) for 3 weeks. Body weight and abdominal circumference were measured twice weekly. At the end of the experiment, mice were sacrificed, ascites volume was measured, and tumors were excised. Mean tumor burden in the LY294002-treated group was reduced by approximately 65% versus controls. Virtually no ascites developed in the treatment group; mean volume of ascites in controls was 3.3 +/- 0.38 ml. OVCAR-3 cells also were cultured in vitro without and with LY294002 (1, 5, and 10 microM) for 24 h. The number of cells in 1, 5, and 10 microM LY294002-treated wells was reduced by 27, 56, and 75%, respectively, versus controls. In vivo and in vitro morphological studies demonstrated that LY294002 induced marked nuclear pyknosis and diminished cytoplasmic volume in the tumor cells, confirmed as apoptosis. Thus, LY294002 significantly inhibits growth and ascites formation of ovarian carcinoma in vivo and markedly inhibits ovarian cancer cell proliferation in vitro, suggesting an important role of PI3-K inhibitors as a potentially useful treatment for women with ovarian carcinoma.

Animals↗
PubMed2000

14-3-3 proteins and survival kinases cooperate to inactivate BAD by BH3 domain phosphorylation.

The Bcl-2 homology 3 (BH3) domain of prodeath Bcl-2 family members mediates their interaction with prosurvival Bcl-2 family members and promotes apoptosis. We report that survival factors trigger the phosphorylation of the proapoptotic Bcl-2 family member BAD at a site (Ser-155) within the BAD BH3 domain. When BAD is bound to prosurvival Bcl-2 family members, BAD Ser-155 phosphorylation requires the prior phosphorylation of Ser-136, which recruits 14-3-3 proteins that then function to increase the accessibility of Ser-155 to survival-promoting kinases. Ser-155 phosphorylation disrupts the binding of BAD to prosurvival Bcl-2 proteins and thereby promotes cell survival. These findings define a mechanism by which survival signals inactivate a proapoptotic Bcl-2 family member, and suggest a role for 14-3-3 proteins as cofactors that regulate sequential protein phosphorylation events.

14-3-3 Proteins↗
PubMed2000

Bcl-2 and Bax are differentially expressed in hyperplastic, premalignant, and malignant lesions of mammary carcinogenesis.

Previously, we found that vorozole (Vz), a nonsteroidal aromatase inhibitor, suppresses the development and progression of mammary tumors in rats. Here we evaluated for the first time the expression of cell death-related proteins Bcl-2 and Bax in hyperplastic, premalignant (carcinoma in situ), or malignant (carcinoma) lesions of mammary carcinogenesis; we also assessed whether these proteins are involved in mediating Vz-induced cell death in tumors. We found that Bcl-2 and Bax were equally expressed in epithelial cells of terminal end buds, ducts, and alveoli. However, in myoepithelial cells, the level of Bax expression was much higher than the level of Bcl-2 expression. Bcl-2 and Bax levels in hyperplastic lesions were similar to those of normal mammary epithelial cells but lower in most carcinomas in situ and carcinomas. In animals with established mammary tumors, Vz induced apoptotic cell death, which was primarily associated with a decrease in Bcl-2 and, to a lesser extent, with a decrease in Bax. These data support the hypothesis that Bcl-2 loss is more potent than Bax gain in regulating apoptotic cell death in mammary tumors.

Animals↗
PubMed2000

[Study on the FcepsilonRI-beta polymorphism and susceptibility of asthma in a Chinese population].

OBJECTIVE: To investigate the linkage between the polymorphisms of FcepsilonRI-beta gene and susceptibility of asthma in a Chinese population. METHODS: Thirty-two families with 192 samples and 122 cases of childhood asthma were studied. A coding variant of E237G was detected by PCR/XmnI restriction endonuclease digestion. Two RsaI polymorphic sites within non-coding region were tested by PCR/RsaI restriction endonuclease digestion. RESULTS: The allele frequencies for all three polymorphisms of FcepsilonRI-beta gene in the Chinese population were markedly different from those published results of Caucasians and Japanese. Comparing asthma family samples with normal control, we found that genotypes containing A allele within intron 2 polymorphic site were associated with asthma (P < 0.05, OR = 2.039). The level of total serum IgE showed significant difference among three genotypes of intron 2 polymorphic site (P < 0.05). The association between A allele and elevated total serum IgE was also significant (P < 0.05, RR = 1.361). We could not find any significant results from the other two polymorphisms, even in the coding variant E237G. CONCLUSION: We were unable to confirm that the FcepsilonRI-beta gene was crucial to the susceptibility of asthma and atopy and did not contribute substantially to variation in IgE levels from both sample groups.

Adolescent↗
PubMed2000

[Cervical spine operation using coralline hydroxyapatite].

OBJECTIVE: To study the result of using coralline hydroxyapatite (CHA) in cervical anterior fusion and posterior laminoplasty operation. METHODS: 45 patients of cervical operation using CHA were followed up. Of these patients, 27 received anterior fusion and titanium plate fixation (34 levels fused). 18 with spinal stenosis at least at 3 levels, (posterior spinal process-splitting laminoplasty) had 79 split spinal processes fused by CHA. The average follow-up time was 25.9 months. RESULTS: The union rate of CHA was 85.3% in average by anterior approach. The height and angle of the fused level and the anterior salient were well maintained. The JOA score improvement rate was 58.7%. The CHA grafts were kept well between the split spinous processes with a union rate of 70.9%. After operation, the spinal cord moved dorsally, and the flat rate was improved from 0.19 to 0.41. No apparent posterior salient occurred. The JOA score improvement rate was 51%. CONCLUSION: The effect of CHA in cervical antero posterior operation is similar to that of autograft bone, and it is unnecessary to resect a piece of bone from a health region of the body.

Adult↗
PubMed2000

[Seven years' summary report on the treatment of acute promyelocytic leukemia with arsenic trioxide--an analysis of 242 cases].

OBJECTIVE: To observe the effectiveness of arsenic trioxide (As(2)O(3)) in the treatment of acute promyelocytic leukemia (APL). METHODS: Data of clinical observation, seven year follow-up survey were analysed with American SAS system software, concentration of arsenic in cerebrospinal fluid (CSF) was determined by atomic absorbing spectrum. RESULTS: The complete remission (CR) and effectiveness rates were 87.9% and 94.4% for the previously untreated group; 60.0% and 65.0% for the relapsed in As(2)O(3) maintenance treatment group; 69.5% and 84.8% for the relapsed in other than As(2)O(3) maintenance treatment group; and 48.7% and 94.1% for the refractory group, respectively. In the previously untreated group, the relapse rate at 3 years after CR was 26.7%. The probability of survival in 136 follow-up survey patients was 92.0% and 76.7% at 5 years and 7 years, respectively. There were mild side effects. Central nervous system leukemia (CNSL) occurred in 138 out of 412 cases in 6 years, including some refractory leukemia, extramedullary residual leukemia and extramedullary relapse. Prophylactic intrathecal injection could reduce the incidence rate of CNSL. Determination of arsenic concentration indicated that it was difficult for arsenic to penetrate the blood-brain barrier. CONCLUSION: The CR rate and long-term survival are high and the relapse rate is low in APL patients treated with As(2)O(3). There is no cross-resistance between ATRA and As(2)O(3) and other chemotherapeutic agents. As(2)O(3)-resistance occurs scarcely. It can also be used in maintenance treatment.

Adolescent↗