Search PubMed⌕ Search

Biomedical subjects

S Cornain

Publications and source records attributed to S Cornain.

16 recordsLinked to original sources
PubMed2001

Development of a yeast stop codon assay readily and generally applicable to human genes.

We established a yeast-based method to screen chain-terminating mutations that is readily applicable to any gene of interest. Based on the finding that 18- to 24-base-long homologous sequences are sufficient for gap repair in vivo in yeast, we used a strategy to amplify a test-gene fragment with addition of 24-bp sequences homologous to both cut-ends of a yeast expression vector, pMT18. After co-transformation with the amplified fragment and the linearized pMT18, each yeast (Saccharomyces cerevisiae) cell automatically forms a single-copy circular plasmid (because of CEN/ARS), which expresses a test-gene::ADE2 chimera protein. When the reading frame of the test-gene contains a nonsense or frameshift mutation, truncation of the chimera protein results in lack of ADE2 activity, leading to formation of a red colony. By using a nested polymerase chain reaction using proofreading Pfu polymerase to ensure specificity of the product, the assay achieved a low background (false positivity). We applied the assay to BRCA1, APC, hMSH6, and E-cadherin genes, and successfully detected mutations in mRNA and genomic DNA. Because this method--universal stop codon assay--requires only 4 to 5 days to screen a number of samples for any target gene, it may serve as a high-throughput screening system of general utility for chain-terminating mutations that are most prevalent in human genetic diseases.

Adenomatous Polyposis Coli Protein↗
PubMed2000

Fat intake and breast cancer risk in an area where fat intake is low: a case-control study in Indonesia.

BACKGROUND: Associations of fat and other macronutrients with breast cancer risk are not clear in areas where fat intake is low. METHODS: We conducted a hospital-based case-control study from 1992 to 1995 in Jakarta, Indonesia. RESULTS: The study, based on 226 cases and 452 age and socioeconomic status matched controls, provided the following findings. (a) In the pre-marriage period, the greater the fat or protein consumption, the larger the risk, whereas decreasing risk with increasing carbohydrate intake was detected. The odds ratio (OR) for the highest quartile of intake relative to the lowest was 8.47 (95% CI: 4.03-17.8) for fat, 2.19 (95% CI: 1.30-3.69) for protein, and 0.16 (95% CI: 0.08-0.31) for carbohydrate. A positive association with fat and a negative one with carbohydrate were also observed for the post-marriage period, but of weaker magnitude compared to the pre-marriage period. (b) The effects of macronutrient intakes were stronger among premenopausal than among postmenopausal women. (c) Most of the associations of protein and carbohydrate were insignificant after adjustment for fat intake. CONCLUSIONS: These findings suggest that fat intake might be an important determinant of breast cancer among populations with a low fat diet in Indonesia.

Adult↗
PubMed1995

Reduced endothelial cell migratory signal production by endometrial explants from women using Norplant contraception.

Bleeding problems can be one of the major reasons for women to discontinue the use of hormonal contraceptives. Causes of endometrial bleeding can include disturbances in endometrial regeneration and angiogenesis. Endothelial cells migrate and proliferate rapidly as part of the angiogenic process under the influence of appropriate stimuli. The aim of this study is to investigate the production of endothelial cell migratory signals by endometrial explants from women receiving Norplant and to compare it to that of those with a normal menstrual cycle. The subjects were selected from Norplant users with an exposure of 3-9 months. The endothelial cell migratory signal production was assayed using the Folkman method (1989), modified by Rogers (1992). Blood serum concentrations of oestradiol, progesterone and sex hormone binding globulin were monitored for 2 weeks prior to endometrial biopsy. Endothelial cell migration toward endometrial explants of 30 women as control and 46 Norplant acceptors was assayed. The results showed that endothelial cell migratory activity toward endometrial explants from the control group was significantly higher than toward those from Norplant acceptors (z = 3.89, P < 0.001). There were no differences between endometrial endothelial cell migratory activities in Norplant acceptors with bleeding or without bleeding problems.

Adolescent↗
PubMed1987

Immunological changes and recovery in patients with dengue haemorrhagic fever.

In studying the immunological changes in dengue haemorrhagic fever, three phases of investigations had been carried out. During the earlier phase of investigation, significant immunological findings were obtained, namely the elevation of immunoglobulins, activation of complements, formation of circulating-immune-complexes and diminished number of T lymphocytes. The changes tended to recover during the convalescent phase. During the second phase of investigation, the extended studies revealed further confirmation of T cell impairment during the acute phase which tended to recover during the convalescent phase. Elevated number of Fc-receptor- and C3-receptor-bearing cells was also observed in some patients, variedly occurred during the acute or the convalescent phase. Elevated number of B cells was only found in small proportion. Significantly high number of activated RNA-rich lymphocytes was found in almost the half of patients. The virus-lymphocyte interaction has been demonstrated by the detection of viral antigen on the surface of lymphocytes in a proportion of patients. The circulating-immune-complexes was shown to contain viral (DEN-1) antigen. During the third phase of investigation, the impairment of T cells was further analyzed on their regulatory T populations. Impairment of total T lymphocytes, helper-T and suppressor-T was detected during the acute phase and tended to recover during the convalescent phase. The reversed changes occurred on B cells, The immunological changes and recovery are considered to be related to the stimulatory and suppressive effects of the dengue virus and regulatory mechanism.

Antibody Formation↗
PubMed1978

Characteristics and in vitro growth influencing effects of the spleen cell population in a methylcholanthrene induced mouse sarcoma system.

Effects of immunization on the growth of the early passages of two methylcholanthrene induced mouse tumors, MC57 X and MC57 Y, were different. For tumor X, immunization resulted in complete protection, while tumor Y was enhanced. The enhancing effect was individual tumor specific. The spleens of tumor bearing animals were enlarged and the proportion of blasts, EAC- and EA-rosettes were increased. This was the case for the T cell enriched population also. In lesser extent, such findings were also obtained in the lymph nodes. The spleens of control and tumor bearer animals were tested for effect on the in vitro growth of tumor cells. From both sources non-adherent subpopulations enriched in C3 receptor bearing cells substantially reduced the number of tumor cells. Using the T cell fractions, only those derived from tumor bearer spleens were active. The in vitro effects on the growth of the two tumors were cross-reactive. T cells exhibiting growth inhibition in vitro were detectable 13 days after subcutaneous inoculation, when the tumor was already measurable, while earlier the T cells enhanced the growth. The outcome of the in vitro tests reflected only the tumorous status of the animal and did not relate to preimmunization.

Animals↗
PubMed1977

Characterization of human lymphocyte subpopulations for cytotoxicity against tumor-derived monolayer cultures.

Lymphocyte fractions of three healthy donors were tested for cytotoxicity in a 48-h assay on several tumor-derived lines. Analysis of surface markers indicated that a non-T non-B fraction comprising about 50% Fc-receptor-positive cells was most potent. The cell yield in this fraction was on the average 6.5% of the non-fractionated population. Elimination of Slg positive cells did not influence the cytotoxic potential. Pure T cells isolated with E-rosetting subsequent to passage on nylon wool column had no or very low low cytotoxicity. We had indications that cells without conventional markers--"null" cells--were also cytotoxic.

Cell Line↗
PubMed1977

Sensitization of rat T cells to syngeneic tumor cultures by cocultivation in diffusion chambers.

Total population and T cell enriched fractions of rat spleen were cultivated in diffusion chambers implanted intraperitoneally to mice and rats. 10-16% of the input cells were recovered after 5 days. When the chambers were carried in the xenogeneic environment activation occurred as indicated by blastogenesis and non-discriminative cytotoxicity. Specific activation of the T population was induced by mixed lymphocyte-tumor culture in chambers implanted in rats. The presence of tumor cells induced blastogenesis, elevation of the proportion of Fc receptor positive cells and generated cytotoxic cells to the sensitizer tumor. The precursor of cytotoxic cells did not have Fc or C3 receptors since nylon wool colum passed fractions depleted from these cells by elimination of EA- or EAC-rosettes were also activated.

Animals↗
PubMed1977

Fc receptors on human blood B lymphocytes.

The frequency of Fc-receptor positive B lymphocytes in human blood was investigated. Under the conditions used heat-aggregated gammaglobulin binding and EA(ox)-rosette formation labelled the same lymphocyte populations. Using various techniques, double marking and cell separations the proportion of Fc-receptor positive cells within the surface Ig carrying population was estimated to be between 11-8 and 36-2%. The proportion of SIg carrying cells within the population forming EA-rosettes was between 11 and 26-4%. This represents extreme values due to known technical circumstances.

B-Lymphocytes↗
PubMed1976

Search for anti-tumor response in a bone tumor patient with a long clinical history.

Immunological studies are presented on a patient with a long clinical history suggesting the existence of a tumor-specific immune response. His tumor, first considered benign, progressed to a highly malignant osteosarcoma. Cell-mediated immune reactivity against biopsy cells and against tumor extract was detected in vitro by the autologous tumor stimulation test (ATS) and in vivo by the skin test. In one ATS-test with tumor extract, blastogenesis of T-cells was demonstrated. The amount of Ig(s) in consecutive biopsies increased. Biopsies taken in the later period of the disease stimulated only after trypsin treatment. This stimulation was inhibited by autologous serum or acid eluate of the biopsy. The inhibitory factor in the serum was not intact immunoglobin. Blood lymphocytes did not show a discriminatory or disease-related cytotoxicity, either directly or after co-cultivation with the tumor material. Lymphocytes isolated from one biopsy were non-reactive in both the ATS and the cytotoxicity test.

BCG Vaccine↗
PubMed1975

Antibodies and antigen expression in human melanoma detected by the immune adherence test.

By means of a modified immune adherence (IA) technique, sera from melanoma patients were tested for the presence of antimelanoma antibodies. In total 13/73 sera tested showed a positive IA reaction of which 4/6 sera showed a positive reaction in the autologous situation. Sera from 33 patients with other tumors, 7 patients with non-neoplastic diseases and 50 healthy individuals did not show any IA reactivity towards melanoma cells. The reaction seemed to be selectively directed against tumor-associated antigens (TAA) on melanoma cells. No correlation with the stage of the disease could be found. Longitudinal studies indicated that conversions in antibody activity did not correlate with the clinical state of the patients. There was also no correlation with the corresponding in vitro data obtained in cell-mediated immunity tests. Cell lines and short-term cultures originating from tumors from different melanoma patients shared a common antigenicity. The expression of TAA on cells from a melanoma cell line fluctuated significantly during prolonged culture. The expression of TAA was influenced by the culture conditions and the growth state of the cells. A relation between TAA-expression and cell cycle phase was demonstrated.

Antibodies, Neoplasm↗
PubMed1975

Spleen-cell reactivity against transplanted neurogenic rat tumors induced by ethylnitrosourea: uncovering of tumor specificity after removal of complement-receptor-bearing lymphocytes.

Spleen cells from BDIX-rats bearing either GVlAl-tumor (a syngeneic mixed glioma) or NVlAc-tumor (a cloned syngeneic neurinoma of the peripheral nervous system) were cytotoxic to both tumor cells in vitro. However, the tumors displayed individually distinct antigenic specificities by in vivo rejection tests. Their in vitro cross-reactivity disappeared when a particular subpopulation of the spleen cells was used. The procedure of lymphocyte purification included three consecutive steps: treatment with carbonyl iron and magnetism, passage through a nylon wool column, and finally removal of complement receptor-bearing cells present in the colum-excluded population. Cross-reactivity between the syngeneic tumors persisted after the first two steps of lymphocyte purification. In contrast, specific cytotoxic reactions were observed against each individual tumor subsequent to the removal of the remaining C3 receptor-positive but surface Ig-negative cells. While killer cells were present in normal spleen-cell populations, these were almost completely eliminated by passage through the nylon wool column.

Animals↗
PubMedDate not supplied

Human papillomavirus type 18 and other risk factors for cervical cancer in Jakarta, Indonesia.

Infection with human papillomavirus (HPV) has now been established as a necessary cause of cervical cancer. Indonesia is a country with a high cervical cancer incidence and with the world's highest prevalence of HPV 18 in cervical cancer. No information exists about the prevalence of HPV 18 or other HPV types in the Indonesian population. We conducted a hospital-based case-control study in Jakarta, Indonesia. A total of 74 cervical carcinoma cases and 209 control women, recruited from the gynecological outpatient clinic of the same hospital, were included. All women were HPV typed by the line probe assay, and interviews were obtained regarding possible risk factors for cervical cancer. HPV was detected in 95.9% of the cases and in 25.4% of the controls. In the control group, 13.4% was infected with a high-risk HPV type. HPV 16 was detected in 35% of the case group and in 1.9% of the control group and HPV 18 was identified in 28% of the case group and in 2.4% of the control group, suggesting that the oncogenic potentials of HPV 16 and HPV 18 in Indonesia are similar. In addition to HPV infection, young age at first intercourse, having a history of more than one sexual partner, and high parity were significant risk factors for cervical cancer. Within the control group, we did not identify determinants of HPV infection. We hypothesize that the high prevalence of HPV 18 in cervical cancer in Indonesia is caused by the high prevalence of HPV 18 in the Indonesian population.

Adult↗
PubMedDate not supplied

Decreased CD4+/CD8+ ratio in major type of recurrent aphthous ulcers: comparing major to minor types of ulcers.

The etiology of recurrent aphthous ulcers (RAU) has not been clearly defined. However, the results of several studies indicated the evidence of the role of immunological factors. The association between the regulator and effector component of the immune system in RAU needs clarifying by comparing major and minor type of RAU patients. The proportion of peripheral blood lymphocyte subsets were enumerated during active ulcer phase and analyzed in relation to ulcer types. Nineteen patients with RAU (12 minor type and 7 major type) and 8 healthy volunteers, of both sexes, aged 24-54 years old were tested. CD3+ (T cell), CD4+ (helper T cell), CD8+ (suppressor/cytotoxic T cell), CD19+ (B cell), and CD16+/CD56+ (NK cell) were determined by using appropriate monoclonal antibodies in double colored flow cytometry. The results showed that CD4+ was lower in RAU than control (P < 0.01). Comparing both types of RAU, it appeared that CD8+ was higher in the major type than the minor type (p < 0.01); CD4+/CD8+ ratio in the major type was lower than the minor type (P < 0.01). There was no difference in CD19+ and CD16+/CD56+ between any groups compared. The finding indicated that RAU was associated with abnormal proportions of CD4+ and CD8+ cells which was dependent on the severity of the lesion.

Adult↗