CDX2 promotes anchorage-independent growth by transcriptional repression of IGFBP-3

CDX2 is a Drosophila caudal-related homeobox transcription factor that is important for the establishment and maintenance of intestinal epithelial cells. We have reported that CDX2 promotes tumorigenicity in a subset of human colorectal cancer cell lines. Here, we present evidence that CDX2 negatively regulates the well-documented growth inhibitor insulin-like growth factor binding protein-3 (IGFBP-3). Specifically, CDX2 binds to the IGFBP-3 gene promoter and can repress IGFBP-3 transcription, protein expression and secretion. Furthermore, inhibition of IGFBP-3 partially rescues the decreased anchorage-independent growth phenotype observed in CDX2 knockout cells. These data demonstrate for the first time that (1) CDX2 can function as a transcriptional repressor, and (2) one mechanism by which CDX2 promotes anchorage-independent growth is by transcriptional repression of IGFBP-3.

CDX2 does not suppress tumorigenicity in the human gastric cancer cell line MKN45

CDX2 is a Drosophila caudal-related homeobox transcription factor that is expressed specifically in the intestine. In mice, ectopic expression of CDX2 in the gastric mucosa gives rise to intestinal metaplasia and in one model, gastric carcinoma. In humans, increased CDX2 expression is associated with gastric intestinal metaplasia and tubular adenocarcinomas. These patterns of expression have shown that CDX2 is important for the initiation of intestinal metaplasia in the gastric mucosa, but the role of CDX2 in established gastric cancer remains unclear. We sought to determine whether CDX2 contributes to tumorigenic potential in established gastric cancer. The CDX2 gene in MKN45 gastric carcinoma cells was disrupted using targeted homologous recombination. The resulting CDX2-/- cells are essentially identical to their parental cells, with the exception of CDX2 ablation. We found no significant differences in the proliferation of CDX2-/- cells compared to CDX2+/+ cells, in vitro or in vivo. Molecular analyses show that loss of CDX2 predominantly altered the expression of genes involved in intestinal glandular differentiation and adhesion. However, there were no microscopic differences in tumor differentiation. We conclude that disruption of CDX2 in MKN45 cells does not significantly affect their tumorigenic potential.

CDX2 has tumorigenic potential in the human colon cancer cell lines LOVO and SW48

CDX2 is a Drosophila caudal-related homeobox transcription factor that is important for the establishment and maintenance of intestinal epithelial cells. CDX2 is a marker of colon cancer, with strong staining in up to 90% of colonic adenocarcinomas. CDX2 heterozygous-null mice develop colonic neoplasms, which have suggested that CDX2 is a tumor suppressor. However, CDX2 has not been reported to affect xenograft growth. Furthermore, CDX2 is rarely mutated in colon cancer, which has led to suggestions that it may play only a minor role as a tumor suppressor in colon cancer. To understand the functional contributions of CDX2 to colon cancer, we disrupted CDX2 in LOVO and SW48 human colon cancer cell lines by targeted homologous recombination. Consistent with the literature, disruption of CDX2 enhanced anchorage-dependent cell proliferation. However, homozygous loss of CDX2 led to significant inhibition of anchorage-independent growth in LOVO cells, and cell lethality in SW48 cells. Further analyses revealed that disruption of CDX2 led to anchorage-independent G1 to S growth arrest and anoikis. In vivo xenograft studies confirmed that disruption of CDX2 inhibited LOVO tumor growth. These data demonstrate that CDX2 mediates anchorage-independent growth and survival. Thus, CDX2 has tumorigenic potential in the human colon cancer cell lines LOVO and SW48.

The situation of malaria along the Vietnam-Lao PDR border and some related factors

This was a descriptive cross sectional study. It was done in 4 communes along the Vietnam-Lao PDR border of two mountainous provinces: Sonla and Nghean. The cluster multistage sampling technique was applied to choose the study sites. The results of the study show: Among the 2,441 persons given blood tests to find malaria parasites, 0.7% of them carry malaria parasite, of whom 0.6% carry P. falciparum and 0.1% carry P. vivax. The malaria morbidity in the year was 6.9%. The mortality due to malaria is 1.59 per 100,000 population per year. Among the 106 hamlet motivators being interviewed, only 75.5% knew that malaria is transmitted by mosquitos, 71.7% knew that malaria patients are a source of transmission, over 50% of the motivators have mistaken understanding about the living environment of malaria mosquitos. Most of them have had mistakes in diagnosis, treatment of malaria, mosquito-killing spraying. Among the 729 adults being interviewed, 59.0% did not know about the causes of malaria, 30.7% did not take part in malaria control activities. Only 69.3% of the adults regularly sleep inside mosquito nets, 68% of adults buy medicine to cure malaria, 39.9% referred patients to health facilities for cure, and 25% use forest herbs to cure malaria. The factors that increased the malaria morbidity in communes along Vietnam-Lao PDR border have been identified.

The epidemiology and disease burden of rotavirus in Vietnam: sentinel surveillance at 6 hospitals

The disease burden of rotavirus diarrhea in Vietnam was assessed by surveillance of children <5 years old who were hospitalized for diarrhea at 3 centers in the north and 3 centers in the south. Rotavirus was identified in 56% (range, 47%-60%) of the 5768 patients surveyed between July 1998 and June 2000. G-typing of the first 224 strains indicated that only 2% were non-typeable, 9% were in mixed infections, and the remainder were of the common serotypes G1, G2, G3, G4, and G9. In Vietnam, diarrhea accounts for 9880 deaths per year, which is approximately 15% of all deaths among children <5 years old, or 6.5 deaths per 1000 children. If even 50% of these diarrhea-related deaths in Vietnam were due to rotavirus, the number would represent 4%-8% of all deaths among children <5 years old, 2700-5400 rotavirus-related deaths per year, and 1 death per 280-560 children during the first 5 years of life. Thus, the disease burden of rotavirus in Vietnam is substantial, and programs to encourage the use of oral rehydration should be encouraged while efforts to develop vaccines continue.

The epidemiology of typhoid fever in the Dong Thap Province, Mekong Delta region of Vietnam

A population-based surveillance for typhoid fever was conducted in three rural communes of Dong Thap Province in southern Vietnam (population 28,329) for a 12-month-period starting on December 4, 1995. Cases of typhoid fever were detected by obtaining blood for culture from residents with fever > or = 3 days. Among 658 blood cultures, 56 (8.5%) were positive for Salmonella typhi with an overall incidence of 198 per 10(5) population per year. The peak occurrence was at the end of the dry season in March and April. The attack rate was highest among 5-9 year-olds (531/10(5)/year), and lowest in > 30 year-olds (39/10(5)/year). The attack rate was 358/10(5)/year in 2-4 year-olds. The isolation of S. typhi from blood cultures was highest (17.4%) in patients with 5 to 6 days of fever. Typhoid fever is highly endemic in Vietnam and is a significant disease in both preschool and school-aged children.

Occupational exposure and chronic respiratory symptoms--a population based study in Vietnam

In order to investigate the relationship between occupational exposure to dust/chemicals (toxic gases/fumes) and chronic respiratory symptoms in Vietnam, the questionnaire standardized by the American Thoracic Society was applied to 368 subjects living in Ha Thai district of Vietnam. According to the results of multiple logistic regression analyses, the odds ratios of chronic respiratory symptoms by occupational exposure are over unity, except for the relationship between chronic cough and occupational exposure to chemicals. Especially for chronic breathlessness, significantly higher odds ratios are observed among people with a history of occupational exposure to dust or chemicals: 2.925 (95% CI: 1.130-7.574) for dust, and 3.721 (95% CI: 1.412-9.803) for chemicals. As for the interaction between occupational exposure to dust and cigarette smoking, it is considered that occupational exposure leads to an increase in chronic respiratory symptoms independent of the effects of cigarette smoking.

Long-term evaluation of immune status in leprosy patients undergoing multiple drug therapy

A long-term survey of leprosy patients of all clinical types, starting at the time of diagnosis, was carried out to monitor clinical, bacteriological and immunological parameters at regular intervals during multiple drug therapy (MDT). The patients were assigned to two groups for treatment following WHO guidelines: paucibacillary (PB) and multibacillary (MB). Immunoglobulin levels, specific antibodies, skin-test responses to different soluble mycobacterial antigens (new tuberculins), and in vitro proliferative responses to mitogens and to antigens were measured during treatment, as were clinical changes, the bacterial index, and clinical improvement. No exact relations between disease activity and IgM antibody levels, both IgM immunoglobulin and specific IgM antibody to a species-specific antigen (ND-O-BSA), could be seen for MB patients. Changes in in vitro cell-mediated immunity and skin-test response seemed to be more directly related to the bacterial load and could reflect the improvement of bacteriological and clinical parameters during MDT.

Use of a yeast site-specific recombinase to generate embryonic mosaics in Drosophila

An efficient method for generating embryonic mosaics using a yeast site-specific recombinase (FLP), under the control of a heat shock promoter, is described. FLP-recombinase can promote mitotic exchange between homologous chromosomes that contain FRT (FLP Recombination Target) sequences. To demonstrate the efficiency of FLP-recombinase to generate embryonic mosaics, clones of the recessive and cell autonomous mutation armadillo (arm), detected by their ability to differentiate ectopic denticles in the naked cuticle of each abdominal segment, have been induced. We have analyzed the parameters of FLP-recombinase induced embryonic mitotic recombination and have demonstrated that clones can be efficiently induced during the postblastoderm mitotic divisions. We discuss applications of this technique for the analyses of the roles of various mutations during embryonic patterning.

Freeze-etching and freeze-fracture structural features of cell envelopes in mycobacteria and leprosy derived corynebacteria

The structural properties of the cell wall and cell membrane of several mycobacteria and of Leprosy Derived Corynebacteria are investigated by freeze-etching and freeze-fracture. In all cases the freeze-fracture split the cell wall in two asymmetric halves. The cell wall fracture faces of the mycobacteria are characterized by a filamentous network which vary with respect to the amount and complexity among microorganism of the same species and even more of different species. In LDC the structure organization of the cell wall and cell membrane differs from that of mycobacteria. The most stricking difference is the presence on the fracture faces of the LDC cell wall of different classes of particulated entities of yet unknown nature. In the mycobacteria and LDC the periseptal annuli likely provide a potential frame for cell envelope and cell membrane assembly.

The humoral antibody response to Shigella dysenteriae type 1 infection, as determined by ELISA

An enzyme-linked immunosorbent assay (ELISA) for determining the class-specific humoral antibody response to the lipopolysaccharide antigen from Shigella dysenteriae serotype 1 bacteria has been tested. Two or more serum samples from each of 60 persons infected with this organism during a dysentery outbreak in a boarding school for young men near Haiphong, Viet Nam, and single serum samples from 39 healthy Vietnamese and from 20 healthy Swedes were included in the study. Comparison of the titres in the sera from the patients and the Vietnamese controls showed that the patients had significantly elevated IgA titres in sera collected 10, 30 and 45 days after onset of infection, and significantly elevated IgG titres in sera collected 30, 45 and 180 days after the onset. The titres in the patients' sera, compared with those in the Swedish controls, were significantly elevated for IgA and IgM as well as IgG in the samples collected after 10, 30, 45 and 180 days. The use of rabbit antisera, specific for enteropathogenic bacteria, and absorption experiments with human sera indicated that the S. dysenteriae type 1 lipopolysaccharide antigen is specific with respect to the O-antigenic polysaccharide chain.

Rosette-forming cells in patients with treated leprosy

White blood cell counts and the percentages and absolute numbers of lymphocytes in the peripheral blood of active lepromatous (BT, BB, BL) leprosy patients, patients with borderline leprosy, and normal controls were determined. Lepromatous patients showed decreased leukocyte counts and elevated percentages of lymphocytes, resulting in normal absolute lymphocyte counts. The proportion of peripheral blood mononuclear cells forming "active" rosettes, standard (4 degrees C overnight) rosettes, and "high affinity" (29 degrees C for 1 hr) rosettes with sheep erythrocytes, and rosettes with EAC were determined. Lepromatous patients, compared with normal controls, had decreased "active" rosettes, standard rosettes, and "high affinity" rosettes with sheep erythrocytes with an increase in the nonrosetting proportion. Both lepromatous and borderline leprosy patients showed increased percentages of EAC rosettes compared with normal controls.