PubMed Health⌕ Search

Biomedical subjects

A Sassen

Publications and source records attributed to A Sassen.

At least 19 recordsLinked to original sources
PubMed2005

[Mini-organ cultures of human nasal mucosa. A model for eco-genotoxicological investigations].

BACKGROUND: Volatile and ingestive xenobiotics may induce cancer in the mucosa of the upper aerodigestive tract. A new model is presented combining mini-organ cultures of human mucosa and the Comet assay that allows investigation of tumor initiation steps in vitro. METHOD: Specimens of human mucosa of the inferior nasal turbinates were cultured as mini-organs and exposed to xenobiotics once, twice or three times with consecutive repair intervals. The cultures were monitored for structural integrity (inverse microscopy, histology), DNA fragmentation and repair activity (Comet assay), induction of apoptosis (annexin V assay), and production of IL-8 and GM-CSF (ELISA). RESULTS: Mini-organ cultures showed a good structural integrity during the whole culture period. Exposure to N-nitrosodiethylamine (NDEA) and benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE) induced significant DNA fragmentation. Sodium dichromate (Na2Cr2O7) had an additive DNA fragmentation effect with repetitive exposure. Significant DNA repair was seen after strand break induction by Na2Cr2O7, only. Apoptosis was seen after three exposures to BPDE und Na2Cr2O7, but not NDEA. Inflammatory cytokine release was unaltered by NDEA. However, BPDE and Na2Cr2O7 reduced GM-CSF and Na2Cr2O7 reduced IL-8 excretion. CONCLUSION: This three dimensional mini-organ culture system proved to be very helpful in characterizing volatile and ingestive xenobiotics potentially hazardous to humans. Beside the information concerning genotoxicity, it allows cytological and immunological studies. In contrast to investigations with fresh specimens, repetitive or chronic exposure to xenobiotics is possible in mucosal cells with their epithelial structural integrity. Therefore, mini-organ cultures of human upper aerodigestive tract epithelia represent a model closely resembling the in vivo situation.

Apoptosis↗
PubMed1980

Detection and spontaneous alteration of lymphocyte antigens on slide smears.

Smears of cell suspensions from murine lymphoid organs were prepared on slides, air dried, and processed for detection of immunoglobulin (Ig) and theta (Thy-1) antigens by the unlabeled antibody peroxidase-antiperoxidase (PAP) technique. Satisfactory results were obtained for both antigens on recently made smears. However, slides kept at room temperature showed a progressive decrease in staining of the two antigens with time. Various fixatives and preservation procedures were tested to prevent this alteration. Good conservation of smears was obtained when slides were kept at -18 degrees C and/or air isolated before or after fixation with alcohols. A similar degradation of Ig and/or Thy-1 antigens occurred also in histological tissue sections or in serum spots dried on slides. The major cause for this degradation is thought to be contact with air, residual enzymatic hydrolysis playing a less important role.

Animals↗
PubMed1979

Radioimmunoassay determination of two main cross-reacting viral antigens during radiation and Rauscher induced leukemias.

The two main proteins p 30 and gp 70 from the Rauscher leukemia virus (RLV) have been isolated, labeled with 125I and used in radioimmune competition assays to estimate the amount of cross-reacting antigens produced during the evolution of various leukemias. The Rauscher leukemia in Balb/c mice, the radiation induced leukemia (RadLV) in C57Bl mice and two types derived therefrom by serial passages in mice (RadLV-RS) and in rats (RadLV-rat) were studied. Whereas the p 30 from RLV or RadLV (rat) viruses showed complete identity, the cross-reaction of their gp 70 proteins wasonly partial. The main findings in the tissues were the following: 1. The concentration of p 30 and gp 70 antigens increased much more during the RadLV-rat leukemia than in irradiated or RadLV (RS) treated mice. 2. In the serum, the ratio p 30/gp 70 was in general higher than one in the Rauscher leukemic mice and less than one in all types of RadLV leukemias. 3. In the spleen, RLV and RadLV (RS) infected mice had higher levels of p 30 than of gp 70. The reverse occurred in irradiated mice and in leukemic rats. Finally, the catabolic degradation of labeled RLV gp 70 was similar in normal and leukemic mice.

Animals↗
PubMed1979

Specific precipitation of mouse and rat alpha 2-macroglobulin by immune sera directed against murine leukemia viruses.

Leukemia viruses preparations obtained from plasma of leukemic mice or rats were used to immunize rabbits. By immunoelectrophoresis, these non-absorbed antisera reacted specifically with one single mouse serum alpha 2 globulin which was further identified as alpha 2-macroglobulin by several criteria, including gel chromatography and nitracentrifugation. When mouse plasma derived virions were used as antigen, they gave rise to antibodies cross-reacting completely with the corresponding mouse and guinea pig protein and partially with rat and calf globulin. Immunization of rabbits with rat plasma derived virions induced antibodies directed preferentially against the rat alpha 2-macroglobulin.

Animals↗
PubMed1977

Regulation of the neutral phosphatase in Chlamydomonas reinhardi: an immunogenetic study of wild-type and mutant strains.

In Chlamydomonas reinhardi, the activity of the neutral phosphatase considerably increases when the cells are grown in the absence of inorganic phosphate (Pi). A comparative immunological study of cells grown on media containing Pi or not indicated that the neutral phosphatase was synthesized de novo. Ten mutants lacking the neutral phosphatase and distributed among three genetic loci (PD2, PD3, PD24) were investigated for their ability to produce cross-reacting material (CRM) antigenically related to the wild enzyme. All mutants were shown to form much less CRM than the wild-type strain. It is proposed that the three genes are involved in the regulation of neutral phosphatase synthesis.

Antigens↗
PubMed1975

[Genetic control in the mouse].

Spontaneous mutations and environmental variations are responsible for the biological instability of inbred strains of mice. As far as possible, all external factors should be kept constant in a modern animal house. Several techniques to analyse part of the genome are available. Due to this limitation, it would be useful to have several laboratories participating to the genetic control.

Animals↗