Biomedical subjects

G O Ness

Publications and source records attributed to G O Ness.

8 recordsLinked to original sources

PubMed1996

Stimulation of glioma-cell migration by laminin and inhibition by anti-alpha3 and anti-beta1 integrin antibodies.

An induction of laminin in the confrontation zone between tumor cells and normal brain tissue has been observed in our model systems in vivo and in vitro. In order to study the effects of ECM components on glioma-cell migration and invasion, we have used 2 lacZ-transfected glioma cell lines, AN1/lacZ and U-251 /lacZ. Cell migration from multicellular spheroids was studied using different types of media: DMEM with 10% serum, Ultra Culture medium, and filtrated DMEM with serum in which the protein fraction > 100 kDa had been removed by ultrafiltration. Laminin, fibronectin and collagen type-IV were individually added to the different media, and cell migration from the spheroids was studied. The results show that cell migration in both cell lines, was stimulated by laminin and fibronectin. Collagen type-IV stimulated only cell migration of U-251/lacZ cells. Scanning electron microscopy revealed an extensive change in cell shape as a result of laminin stimulation. Flowcytometric studies showed that both AN1/lacZ and U-251/lacZ strongly express the alpha3 beta1 integrin receptor, which can bind to several ECM components (laminin, fibronectin, collagen). Immunofluorescence microscopy demonstrated that the same integrin sub-units were expressed in multicellular spheroids. When monoclonal antibodies to alpha3 and beta1 were added to the laminin-stimulated cultures, cell migration was significantly reduced. This indicates that the alpha3 beta1 integrin receptor plays an important role during glioma-cell migration.

Antigens, CD↗

PubMed1996

Cytoplasmic localization of EGF receptor in papillary thyroid carcinomas: association with the 150-kDa receptor form.

We have previously reported that papillary thyroid carcinomas show an increased expression of EGFR mRNA and protein, compared to non-tumorous thyroid tissue. EGFR immunoreactivity was localized to the cytoplasm as well as to the membrane in papillary carcinomas. To further study EGFR protein expression in human thyroid tissue, we performed immunohistochemistry and Western blots of 64 different thyroid tissue samples from 36 patients, including 23 patients with papillary carcinomas. Two receptor forms were identified in human thyroid tissue, a 170-kDa and a 150-kDa form. The 150-kDa receptor form was more pronounced in papillary carcinomas, while the 170-kDa receptor was the dominant form in non-malignant thyroid tissues. Predominance of the 150-kDa EGFR in the tumour samples was associated with strong cytoplasmic EGFR staining. EGFR gene structure, protein synthesis and maturation were found to be normal. Immunoprecipitation and Western-blot analysis of EGFR from the human thyroid SGHTL-34 cells after increased ligand concentration showed a decreased amount of the mature 170-kDa receptor and a relative increase in the 150-kDa receptor. We have previously demonstrated the presence of a TGF-alpha-EGFR autocrine loop in papillary thyroid carcinomas, and this may explain increased receptor turnover and accumulation of a cytoplasmic degradation product.

Blotting, Western↗

PubMed1994

Heterogeneous response to the growth factors [EGF, PDGF (bb), TGF-alpha, bFGF, IL-2] on glioma spheroid growth, migration and invasion.

The effects of 5 different growth factors [EGF, PDGF(bb), TGF-alpha, bFGF and IL-2] were studied on tumour spheroids obtained from 5 different human glioma cell lines (U-251MG, D-263MG, D-37MG, D-54MG, GaMG). The expression of EGF and PDGF receptors as well as the endogenous production of TGF-alpha and PDGF were studied by Northern blot analyses. After growth-factor-exposure, tumour spheroid volume growth, and directional cell migration from the spheroids were studied. In addition, tumour-cell invasion was studied in vitro, where foetal rat-brain aggregates were used as a target for the tumour cells. In all the assays a common stimulator for most of the cell lines was EGF. The other growth factors had a more heterogeneous stimulatory effect. Tumour-cell invasion, cell growth and cell migration are biological properties which are not necessarily related to each other. This may explain why the tumours often responded differently to the growth factors in the various assay systems. Two of the cell lines studied were non-invasive (U-251MG, D-263MG). It is shown that these were stimulated both in the directional migration assay and in the spheroid-volume-growth assay. However, their non-invasive behaviour was not influenced by the growth factors studied.

Animals↗

PubMed1994

Three-dimensional growth of glial cell lines affects growth factor and growth factor receptor mRNA levels.

We have studied, at the mRNA level, the influence of various defined growth conditions on the expression of TGF-alpha, PDGF-BB, EGF-R, PDGF-R alpha, and PDGF-R beta in five different glioma cell lines (D-37MG, D-54MG, D-263MG, GaMG, and U-251MG). RNA isolated from logarithmically growing, confluent monolayer cells or multicellular spheroids was analyzed. Northern blot experiments show that with a few exceptions, specific mRNA steady-state levels were considerably higher in cells grown in a three-dimensional organization relative to cells in the logarithmic growth phase.

Glioma↗

PubMed1993

Growth requirements and oncogene expression in the human thyroid cell line SGHTL-34.

The SV40 T-antigen-transfected human thyroid cell line SGHTL-34 was used to investigate the effect of thyrotropin (TSH), insulin-like growth factor-1 (IGF-1) and epidermal growth factor (EGF) on c-fos and c-erbB/EGF receptor (EGF-R) mRNA expression and their role in human thyroid cell proliferation. EGF caused a transient 8- and 4-fold increase in c-fos mRNA level after 30 min in serum/hormone-deprived and in logarithmically growing cells, respectively. EGF was only mitogenic in the presence of serum, as measured by 3H-thymidine incorporation and cell counting. TSH had no detectable effect on c-fos mRNA expression and no mitogenic effect on the SGHTL-34 cells. IGF-1 showed no effect alone or in combination with EGF or TSH on either proliferation or c-fos mRNA expression. Our data suggest that increased c-fos mRNA levels are part of the mitogenic pathway, but are insufficient to engender a mitogenic response. SGHTL-34 cells produced high levels of transforming growth factor-alpha (TGF-alpha) and c-erbB/EGF-R mRNA, also seen in thyroid papillary carcinomas. The TGF-alpha protein was detected in conditioned medium from the SGHTL-34 cells, indicating that TGF-alpha may function as an autocrine growth factor. Our data show that the c-erbB/EGF-R mRNA level is regulated by growth factors and hormones in the SGHTL-34 cell line. The SGHTL-34 cells may therefore represent a useful model system for studying the role of TGF-alpha and EGF-R in thyroid carcinogenesis.

Antigens, Polyomavirus Transforming↗

PubMed1988

A retrospective cohort mortality study of males mining and milling attapulgite clay.

To evaluate the possible health effects of occupational exposure to a nonasbestos mineral fiber, a cohort of 2,302 males employed for at least 1 month between 1940 and 1975 at an attapulgite (clay fiber) mining and milling facility was followed through 1975. A significant deficit of mortality (SMR = 43, 90% CI 23-76) from nonmalignant respiratory disease (NMRD) was observed for the cohort based on age-, calendar year-, and race-specific rates for U.S. males. A marked deficit of NMRD was seen regardless of presumed dust exposure level, induction-latency period, or duration employed. A statistically significant excess of mortality from lung cancer was observed among whites (SMR = 193, 90% CI 121-293), but a deficit occurred among nonwhites (SMR = 53, 90% CI 21-112). Lung cancer risk in either race was not altered substantially with presumed dust exposure level, induction-latency period, or duration employed with one exception-those employed for at least 5 years in high-exposure-level jobs.

Dust↗

PubMed1983

A modified life-table analysis system for cohort studies.

A person-years at risk life-table analysis system of computer programs has been developed by the National Institute for Occupational Safety and Health (NIOSH) and is available with detailed documentation. The system was specifically designed to analyze occupational cohort mortality data. These programs require more computer core space and processing time than other available life-table programs. However, the NIOSH programs are advantageous because they include the following: (1) input data editing and modification, (2) mortality rates for 89 cause-of-death categories, (3) assignment of cumulative doses to specific person-years based on either personal or area exposure data, and (4) simultaneous examination of observed and expected deaths by duration of employment (or dose), latency, age, and calendar time.

Actuarial Analysis↗

PubMed1982

Mortality patterns of rock and slag mineral wool production workers: an epidemiological and environmental study.

An epidemiological and environmental study of rock and slag mineral wool production workers was undertaken at a plant that has been in operation since the early 1900s. Size characteristics of fibres produced by each process at the plant and data from industrial hygiene surveys were used to evaluate current and past exposures. These data suggest that the average historical airborne fibre concentration probably did not exceed 2.5 fibres/cc before 1935 and 1.0 fibre/cc after 1935. A retrospective cohort mortality study was designed to assess mortality patterns. Detailed occupational histories were compiled on all plant employees. All jobs in the plant were assigned to one of eight potential exposure categories to assess the extent and severity of mineral wool exposure and the effect of other significant exposures on employee mortality. Findings included an increase in the number of deaths due to cancer of the digestive system and non-malignant respiratory disease among workers who had over 20 years' exposure to mineral wool or who had survived 20 years since their first exposure to mineral wool. These findings are not inconsistent with those of Enterline's (Symposium on Biological Effects of Mineral Fibres, Lyon, France, September 1979) in the Thermal Insulation Manufacturers' Association's mortality study of men employed in four mineral wool plants.

Adult↗