PubMed Health⌕ Search

Biomedical subjects

L De Ridder

Publications and source records attributed to L De Ridder.

71 records · Page 4Linked to original sources
PubMed1978

Morphology and 125I-concentration of embryonic chick thyroids cultured in an atmosphere of oxygen.

In vitro culture of whole thyroid glands may lead to loss of differentiation and function. Comparison by histology, histoautoradiography and gammacounting of 125I-concentration, of 12 to 13 days old embryonic chick thyroids, cultured on a gyratory shaker either in an atmosphere of 5% CO2 and air or of 95% O2 and 5% CO2, shows that a high concentration of O2 maintains the morphological and functional integrity of the thyroids for at least 4 days.

Animals↗
PubMed1975

Characterization of spontaneous, chemicak, and viral transformants of a C3H/3T3-type mouse cell line by transplantation into young chick blastoderms.

Cells from a C3H/3T3-type cell line were transplanted into defects of the lower layer of stage-4 chick blastoderms before and after "spontaneous," chemical, and viral transformation. To check the validity of inhibition of lower-layer defect closure as a criterion of malignancy, we compared the behavior of the lower layer toward these cells with their in vitro growth pattern, their capacity to invade embryonic chick skin explants that were organotypicaly cultured, and their tumorigenicity in syngeneic mice. No false-positive results were observed with either test. The study of the in vitro growth pattern gave false-negative results during the early phase of spontaneous transformation, whereas these cells, exhibiting an untransformed growth pattern, were shown to be malignant by the other tests. We concluded that the inhibition of lower-layer defect closure is a reliable, sensitive and rapid test for the detection of malignancy in tissue-cultured cells from any source.

Animals↗
PubMedDate not supplied

Behaviour of gliomas in vitro vs histopathological grading.

Infiltration of primary cultured human gliomas into host tissue in vitro is correlated to the histological grade of tumours they are derived from. The higher the malignancy grade, following the WHO classification, the higher the number of tumours expressing an infiltrative pattern in vitro. To select the putative infiltrative cells from freshly collected brain tumour material, tumour fragments are explanted in vitro and primary monolayers are grown. From these cultures flaps of viable and proliferating tumour-derived cells are placed in contact with embryonic host tissue forming a confrontation culture. If infiltrative cells are present in the monolayer, they will infiltrate into the host tissue and replace it in a progressive way: they express an infiltrative pattern. If no infiltrative cells are present, host and tumour-derived cells will stay together expressing a noninfiltrative pattern. So analysis of the confrontation pattern in vitro observed for individual gliomas, collected by a stereotactic biopsy, might help the neurosurgeon to set up a surgical strategy.

Brain Neoplasms↗
PubMedDate not supplied

Interphase death in human peripheral blood lymphocytes after moderate and high doses of low and high LET radiation: an electron microscopic approach.

Peripheral blood lymphocytes irradiated with low and moderate doses of low linear energy transfer (LET) gamma-rays are known to die by an apoptotic process. In the present study, the type of interphase death occuring after administration of moderate and high doses of low LET gamma-rays and high LET fast neutrons was investigated. Lymphocytes were irradiated in vitro with radiation doses of 5 and 20 gray (Gy) of both radiation qualities. They were cultured for 24 or 48 hours and the type of cell death induced was determined by electron microscopy. After neutron irradiation, a slight increase in the incidence of apoptosis from 5 to 20 Gy was found, whereas after gamma-irradiation, the incidence of apoptosis was lower at 20 Gy as compared to 5 Gy. However, unlike the other radiation doses, the 20 Gy dose of gamma-rays, besides apoptosis also induced oncosis (classical necrosis). According to our experiments, membranes are probably an important target for the induction of interphase death. It is suggested that a great amount of ionisations distributed all over the cell surface, as caused by high doses of gamma-rays, lead to a high influx of Ca++ which induces oncosis instead of apoptosis.

Cell Death↗
PubMedDate not supplied

PCNA, Ki-67 and hTERT in residual benign meningiomas.

BACKGROUND: Relapse in individual patients after incomplete/residual removal of meningiomas cannot be predicted by histology alone as re-growth occurs even in histologically benign meningiomas. MATERIALS AND METHODS: Proliferating cell nuclear antigen (PCNA), Ki-67 and human telomerase reverse transcriptase (hTERT) labelling indices were measured in histological sections derived from residual meningiomas in 37 patients to assess their relationship to relapse. The labelling index (LI) expressed the percentage of tumour cell nuclei immunoreactive for PCNA, Ki-67 or hTERT in 1,000 tumour cells counted per section. The histological specimens comprised the following 2 groups: (i) stable for at least 10 years after initial partial resection of residual meningiomas: 20 specimens; (ii) relapsing between 11 and 145 months after initial resection of residual meningiomas: 17 specimens. RESULTS: The proliferative activity and hTERT expression do not directly correlate with every relapse. The PCNA LI significantly differed in the relapsing group (10.8%) compared to the stable group (5.5%) (p=0.08). The Ki-67 LI also was higher in the relapsing group (2.5%) than in the stable group (2.0%), but not statistically significantly (p=0.9). hTERT LI was significantly higher in the relapsing group (27.8%) than in the stable group (7.2%) (p<0.01). CONCLUSION: The mean PCNA, Ki-67 and hTERT LI were higher in the relapsing group of residual meningiomas than in the stable group, although no statistical difference was found for PCNA and Ki-67. On the other hand, a statistical difference between the two groups of meningiomas was found for hTERT; however, it is no absolute predictor for relapse at the individual patient level.

Adult↗
PubMedDate not supplied

Oncogene transfection of mink lung cells: effect on growth characteristics in vitro and in vivo.

Three sublines have been derived from the parental line Mv1Lu by transfection with normal and mutated Ha-ras, and myc oncogenes, and subsequent cloning. All the oncogenes have increased the growth rate of the cell in vitro, increased their plating efficiency in monolayer and suspension, and reduced their serum dependence. Growth in vivo as xenografts in nude mice has also been increased. Very few tumours were generated from the parental line and those that did form did so after a prolonged lag period, while the transfected lines produced tumours with 100% efficiency, and a short lag period. In general the effects of ras transfection were more extreme, with the highest growth rates and plating efficiencies in vitro and the shortest lag period and doubling times in vivo. There was no increase in plasminogen activator activity as a result of transfection, and the invasive behaviour of the lines in organotypic culture was broadly similar.

Animals↗
PubMedDate not supplied

Transmission electron microscopy of malignant neurogenic rat cells during invasion into embryonic chick heart fragments in vitro.

Invasion of chemically induced brain tumour cells from BD IX-rats into precultured fragments of embryonic chick heart (PHF) was studied by transmission electron microscopy. The malignant cells from monolayer cultures were suspended and allowed to form aggregates for 24 hours on a gyratory shaker. The single aggregates were allowed ro attach to a single PHF and thereafter incubated in a confronting culture on a gyratory shaker. Invasion into the PHF started with cytoplasmic cell extensions between PHF cells and vanishing of heart cell junctions. Irreversible intracellular alterations in heart cells followed the disruption of intracellular contact by the malignant neurogenic cells. The latter exhibited fewer microvilli when invading the PHF than when located at the periphery. No junctions connecting heart cells with neurogenic cells were observed. Malignant cells were lying between the PHF and no extensions were seen in PHF cells. Hetero/autophagosomes were regularly present in the malignant cells and also in PHF cells. The aggregates of the 13 tumourigenic neurogenic cell lines tested, all produced the same alterations in the PHF cells.

Animals↗
PubMedDate not supplied

Invasive pattern and phenotypic properties of malignant neurogenic rats cells in vivo and in vitro.

Twelve malignant neurogenic rat cell lines induced by the carcinogen ethylnitrosourea (EtNU) have been investigated for invasiveness in an in vitro three-dimensional culture system. The histological pattern of invasiveness into embryonic chick heart fragments has been compared to the morphology in subcutaneous and intracerebral solid tumours as well as to other phenotypic properties of the cells. In all the cell lines invasiveness was seen both in vivo and in vitro. The site of in vivo transplantation seemed to influence the tumour-host tissue interface, since intracerebral tumours were more sharply delimited than subcutaneous tumours and primary EtNU-induced CNS tumours. The histological patterns in vivo (glioma versus neurinoma-like) were in most cases similar to invasive growth in vitro. The pattern of invasiveness did not correlate to other phenotypic properties of the cells (e.g. ploidy, doubling time, latency for tumour formation and surface microarchitecture). A rat fibroblastic cell line, RE-E was non-tumourigenic in rats and non-invasive in culture, but formed small subcutaneous tumours in nude mice.

Animals↗
PubMedDate not supplied

In vitro and in vivo models for the study of brain tumour invasion.

Since it is difficult to study the dynamic biological aspects of brain tumour invasion using histological sections of surgical biopsy and autopsy tissues, various laboratory systems have been devised. Animal models are less than ideal as chemically-induced brain tumours suffer from the fact that they have a low incidence and a long latency, while transplanted tumours grow predominantly by expansion, due to high proliferative activity, and not by diffuse local invasion as in human brain tumours. Various in vitro assays have, therefore, been established for both migration and invasion. These include the simple scratch technique in a confluent cell monolayer, the use of cloning rings and the "Transwell" modified Boyden chamber technique. More complex, three-dimensional culture model systems have also been developed, using chick heart, optic nerve or reaggregated fetal brain as "targets" for the invasion of neoplastic glia. Each method has yielded important information on the mechanisms which underlie brain tumour invasion. Moreover, individual microenvironmental factors may be modulated in these laboratory systems to determine their influence on the migration/invasion process.

Animals↗