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Biomedical subjects

J H Daams

Publications and source records attributed to J H Daams.

18 recordsLinked to original sources
PubMed1996

The possible control of chaos in chronic inflammation.

Small differences in inbred animals with a gene for arthritis must be the cause that some of them evolve the disease and others not. These differences are partly stochastic, caused by thermal movement of molecules. It is possible that their effect is amplified by a network of cytokines, known to play an important role in arthritis. Here it is supposed that the cytokines form a chaotic system. Such a system is deterministic but extremely sensitive for small perturbations. However, they can also be used for the control of chaos and this may offer a means of therapy.

Animals↗
PubMed1990

The alpha 6 beta 1 (VLA-6) and alpha 6 beta 4 protein complexes: tissue distribution and biochemical properties.

A member of the integrin family, the alpha 6 beta 4 complex was previously identified on human and mouse carcinoma cell lines by using a rat monoclonal antibody to alpha 6. Here we describe two monoclonal antibodies that recognize epitopes on the beta 4 subunit of the human and mouse alpha 6 beta 4 complexes. The monoclonal antibodies against beta 4 were able to preclear alpha 6 beta 4, but not alpha 6 beta 1 from cell line extracts. A substantial fraction of the total beta 4 subunits present on the cell surface was not associated with alpha 6, as it could not be removed by anti-alpha 6 antibodies, but remained precipitable with anti-beta 4 antibodies. There was no evidence for novel alpha subunits associated with beta 4. The alpha 6 subunit consists of disulfide-linked heavy and light chains. The variability in size of these two chains from different cell types is largely due to differences in modifications of N-linked glycans. Additional heterogeneity may be caused by differential proteolytic cleavage of the alpha 6 precursor. Immunoperoxidase staining of tissue sections of neonatal and adult mice revealed that beta 4 expression is limited to epithelial tissues and peripheral nerves. The alpha 6 subunit has a wider distribution that includes all tissues and cells stained by antibodies against beta 4. Cells and tissue that are positive for alpha 6, but negative for beta 4, may express the alpha 6 beta 1 complex.

Animals↗
PubMed1978

[Control of lymphosarcoma or leukaemia in cats and of feline leukaemia virus (author's transl)].

A removal programme, specially designed for catteries or multiple cat households, to reduce the incidence of lymphosarcoma or leukaemia in cats and the spread of feline leukaemia virus (FeLV), is discussed. This removal programme includes annual testing of male stud cats, testing all contacts of FeLV-positive cats they had during the past two years, testing cats imported from abroad and isolation--or, if this is not possible, euthanasia--of cats found to be positive for FeLV-antigen. To detect the FeLV-antigen a simple indirect fluorescent antibody technique (FAT) was used to detect FeLV-antigen. During a period of four years, the following results were obtained when a removal programme was carried out by a large cat breeders' association in the Netherlands. The proportion of catteries, in which FeLV-positive cats were found to be present, decreased from 11.5 per cent in the former half of 1974 to 2.1 per cent in the latter half of 1977. The proportion of FeLV-positive cats and male studs decreased from 4.9 per cent to 1.2 per cent and from 5.9 per cent to 1.0 per cent respectively during this period. It is concluded that the recommended removal programme is a simple and successful procedure.

Animals↗
PubMed1970

Genetic transmission of viruses that incite mammary tumor in mice.

Electron microscopy, immunofluorescence, and bioassay demonstrated the presence of a mammary tumor inciting virus in untreated mice of three different inbred strains, and in irradiated or urethan-treated mice of two other mouse strains, indicating the ubiquitous nature of this group of viruses. In general these viruses are transmitted vertically by the gametes of the mouse strain in which they naturally occur. The virus is present in every cell, although often in an incomplete form. If a mammary tumor inciting virus is introduced into a different mouse strain, only milkborne transmission will take place, after which the virus is found in a limited number of tissues. It has been speculated that mammary tumor inciting viruses are transmitted as genetic factors of the host strain to which they belong. There is some evidence that a repressor, produced by a regulator gene, controls the rate of release of such a genetically transferred virus. Repression can be abrogated by a carcinogenic treatment. The repressor would also cause resistance to a superinfecting mammary tumor inciting virus by interference with its replication.

Animals↗