Biomedical subjects

J Ponten

Publications and source records attributed to J Ponten.

14 recordsLinked to original sources

PubMed1998

Clonality analysis of cervical cancer on microdissected archival materials by PCR-based X-chromosome inactivation approach.

Clonality of invasive human cervical cancer was assessed in microdissected archival formaldehyde-fixed, paraffin-embedded tissues by PCR-based analysis of X-chromosome inactivation of the androgen receptor gene. In 18 informative cases, cancers from 12 cases including 2 early-invasive cancers were scored as monoclonal. Among them, 8 cases had the combination of random X-chromosome inactivation in normal cervical tissue and non-random in the cancer and in other 4 cases normal and cancer tissue were both non-random but had discordant X-chromosome inactivation. Six cases showed that the non-random inactivation affected the same allele in cancer and normal tissue and thus were considered to be inconclusive. The results suggest the monoclonal origin of cervical cancer and indicate that genetic events are critical in transition of pre-malignant epithelia to invasive cancer in cervical carcinogenesis. Finding of monoclonal early invasive cancer also argues that monoclonality of human tumors is not a late event due to clonal competition or selection. X-chromosome inactivation patterns in normal cervical epithelia and tissues were analyzed in 21 informative cases. When a mixture of normal stroma and epithelium was analyzed, 38% (8/21) of cases showed non-random inactivation pattern, whereas using pure epithelium it was 64% (11/17). The X-chromosome inactivation pattern between mixed epithelium/stroma and matched epithelium differed in 2/8 cases. These results point to a certain amount of overlooked source of error in X-inactivation-based tumor clonality analysis in which peripheral blood monocytes were chosen as control and strongly recommend that control tissues which share close histological origin with analyzed tumors should be selected in any clonality study of human neoplasm. Post-embryological mechanisms of clonal patch in normal cervical epithelia are also discussed.

Carcinoma, Squamous Cell↗

PubMed1989

Histopathological and immunohistochemical analysis of lung tumors: description of a convenient technique for use with fine needle biopsy.

In this paper we describe a convenient procedure for use with fine-needle biopsy in the diagnosis of lung and medistinal tumors. Cells obtained from a fine-needle aspiration are suspended in a formaldehyde solution and allowed to sediment onto a polycarbonate filter, using a filtering device specially designed for this purpose. The filter with the aspirated cells is then embedded in paraffin and thereafter sectioned and stained in a routine manner. The main advantages with this technique, instead of cytology, are: 1. the cells are kept mainly intact, mostly in undisrupted clusters, and this increases the possibility of obtaining a specific diagnosis, a prerequisite for the diversified clinical management of malignant tumors: 2. possibilities exist, when necessary, of further immunohistochemical characterization of tumor cells in order to obtain a specific diagnosis without thoractomy. This could be of major importance when the management of certain tumors and infiltrates (i.e. those preferably treated by radio- and chemotherapy) does not require surgical intervention.

Adult↗

PubMed1984

Nuclear DNA and endocrine activity in carcinomas of the breast.

In a running study of nuclear DNA profiles of female breast carcinomas, 60 consecutive tumors were collected and stained with the Grimelius argyrophil reaction for the identification of endocrine tumor cells. Four (6.7%) tumors were argyrophilic, and they all displayed diploid nuclear DNA values. The argyrophil tumors constituted 20% of the diploid breast carcinomas. One of the tumors was examined electron microscopically and exhibited an abundance of intracytoplasmatic granules of neurohormonal type. In none of the four carcinomas could the endocrine activity be inferred from the morphologic appearance alone, since all could be grouped in regular histopathologic terms. Since the frequency of endocrine cells in unselected materials of breast adenocarcinomas is very low, a relationship exists between diploid nuclear DNA values and with neurohormonal production in these tumors.

Breast Neoplasms↗

PubMed1982

Novel vesicular extrusions during cell spreading.

During the late stages of cell spreading in vitro, the cells extrude a vesicular material into the medium. This phenomenon was observed in human glia and glioma cells as well as in human diploid fibroblasts MRC-5 and WI-38 cells. This extrusion of vesicular material is inhibited by cytochalasin-B and colcemid suggesting the involvement of microfilaments and microtubules and the active nature of this event. It appears that the cells may be excreting damaged surface components by a mechanism similar to patching, capping and endocytosis.

Cell Line↗

PubMed1980

Survival of irradiated glia and glioma cells studied with a new cloning technique.

A method allowing cloning of monolayer cultured cells with a low plating efficiency was developed. Cells were grown in several small palladium squares to obtain a high cell density. These squares were surrounded by non-adhesive agarose to prevent large distance migration and thereby mixing of the clones. By using easily-cloned hamster cells for comparison it was found that the survival curves were similar to the curves obtained with conventional cloning. The new method was used to compare the radiosensitivity of cultured human glia and glioma cells which both have a low plating efficiency (less than 5 per cent) when seeded sparsely. The survival curves for the glioma cells had high Do-values (1.5--2.5 Gy) and large shoulders (extrapolation numbers around 5) indicating that they were rather resistant and had a high capacity for accumulation of sublethal damage. The survival curves for glia cells had lower Do-values (1.3--1.5 Gy) and no shoulders at all, indicating that they were more sensitive than the glioma cells.

Animals↗

PubMed1976

A common cell-type specific surface antigen in cultured human glial cells and fibroblasts: loss in malignant cells.

Fibroblast surface antigen (SFA) is a high molecular weight protein antigen, first shown on the surface of cultured fibroblasts in fibrillar structures. It is shed to the extracellular medium and also present in the circulation (serum and plasma). Fibroblasts transformed by tumor viruses produce SFA but do not retain it on cell surface. In this report we show that SFA is also present in cultured nonestablished astroglial cells. The glial and fibroblast SFAs are immunologically indistinguishable. Glial cells (three different nonestablished lines) contain more SFA per milligram cellular protein than fibroblasts. SFA was located on cell surface in fibrillar striae that frequently extended out from the cell body. Fluorescence was also found intracellularly in the cytoplasm. Malignant gliomas (astrocytomas) established to grow in culture from human tumor material produced SFA into the growth medium but had very little (lines U-105 MG and U-343 MG) or no detectable (lines U-118 MG, U-251 MG, and U-343 MG-a) cell surface SFA. In cultures of the glioma cells many cells, in particular those that appeared to be in the telophase stage, stained strongly positive for intracellular cytoplasmic SFA. These data demonstrate that similar to fibroblasts transformed experimentally by oncogenic viruses, cells grown from naturally occurring human tumors (glioblastomas) produce SFA but lose ability to retain it on cell surface.

Antibodies↗

PubMed1976

Alpha-aminoisobutyric acid transport into human glia and glioma cells in culture.

The AIB transport into human glia and glioma cells in culture has been studied. Because of the high affinity of AIB to the plastic culture dishes, a special washing technique had to be developed. With this technique, it was possible to perform transport experiments in a single plate containing about one million cells. The cells were viable, intact and adhered to the supporting medium throughout the experiment. The AIB transport into both types of cells was Na+-dependent and showed saturation kinetics when the small component of the transport due to diffusion had been subtracted. The AIB transport capacity of neoplastic glioma cells was 3.6 times higher than that of glia cells. This difference was related to the Vmax-values for the two types of cells. The apparent Km-values were the same. Inhibition experiments with other amino acids support the view that AIB is transported via System A in both glia and glioma cells. Sulfhydryl reagents (ethacrynic acid and NEM) and cytochalasin B clearly inhibited the AIB transport into glia cells whereas the effect on glioma cells was minimal.

Amino Acids↗

PubMed1974