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K I Matthaei

Publications and source records attributed to K I Matthaei.

53 records · Page 3Linked to original sources
PubMed1997

The isolation and cloning of chromosomal DNA specific for a clonal population of Staphylococcus aureus by subtractive hybridisation.

Subtractive hybridisation was used to screen for and identify conserved DNA sequences associated with clinical, clonal populations of Staphylococcus aureus. DNA from S. aureus strain ISP8 (a clinical isolate) was digested with TaqI and hybridised with randomly fragmented pooled DNA from 10 non-clinical (community) isolates of S. aureus. The mixture of DNA fragments was then ligated to AccI-digested and dephosphorylated pTZ19U. One recombinant plasmid (pWASA) was identified as containing specific DNA from strain ISP8; DNA sequencing revealed a 40-bp TaqI DNA fragment (WASA). PCR amplification and hybridisation analysis, with pWASA as a probe, showed that 84% of clinical isolates from a clonal line present in hospitals in major eastern Australian cities carried sequences homologous to WASA, compared with only 10% of community isolates. The isolates that hybridised were closely related by RFLP analysis to strain ISP8. The plasmid pWASA was used to identify, isolate and clone a 3.5-kb DraI fragment (DSA) from strain ISP8 total DNA. Sequence analysis of the DSA fragment identified two open reading frames (ORFs) of 2475 and 576 bp, respectively; the larger ORF1 contained a series of six tandem repeats, each consisting of 384 nucleotides. The nucleotide sequence of the repeats was 96% identical, and no significant sequence homologies to previously described protein sequences were identified. However, tandem repeats of amino acids are structural motifs characteristic of a number of gram-positive surface proteins, and are thought to play a role in generating genetic and phenotypic diversity in these and other bacteria.

Amino Acid Sequence↗
PubMed1997

Interleukin-4 and interleukin-5 as targets for the inhibition of eosinophilic inflammation and allergic airways hyperreactivity.

Clinical and experimental investigations suggest that allergen-specific CD4+ T-cells, IgE and the cytokines IL-4 and IL-5 play central roles in initiating and sustaining an asthmatic response by regulating the recruitment and/or activation of airways mast cells and eosinophils. IL-5 plays a unique role in eosinophil development and activation and has been strongly implicated in the aetiology of asthma. The present paper summarizes our recent investigations on the role of these cytokines using cytokine knockout mice and a mouse aeroallergen model. Investigations in IL-5-/-mice indicate that this cytokine is critical for regulating aeroallergen-induced eosinophilia, the onset of lung damage and airways hyperreactivity during allergic airways inflammation. While IL-4 and allergen-specific IgE play important roles in the regulation of allergic disease, recent investigations in IL-4-/- mice suggest that allergic airways inflammation can occur via pathways which operate independently of these molecules. Activation of these IL-4 independent pathways are also intimately associated with CD4+ T-cells, IL-5 signal transduction and eosinophilic inflammation. Such IL-5 regulated pathways may also play a substantive role in the aetiology of asthma. Thus, evidence is now emerging that allergic airways disease is regulated by humoral and cell mediated processes. The central role of IL-5 in both components of allergic disease highlights the requirements for highly specific therapeutic agents which inhibit the production or action of this cytokine.

Animals↗
PubMed1997

The role of interleukin-5 (IL-5) in vivo: studies with IL-5 deficient mice.

Eosinophil recruitment is a characteristic feature of a number of pathological conditions and was the topic of the recent International Symposium on allergic inflammation, asthma, parasitic and infectious diseases (Rio de Janeiro, June 3-5, 1996). Since interleukin-5 (IL-5) is believed to regulate the growth, differentiation and activation of eosinophils (Coffman et al. 1989, Sanderson 1992), the role of eosinophils and IL-5 are closely linked. Although IL-5 specifically regulates eosinophilia in vivo and this is its most well established activity, it is becoming clear that IL-5 also has other biological effects. The recent derivation of an IL-5 deficient mouse (Kopf et al. 1996), provides a model for exploring not only the role of IL-5 and eosinophils but also other novel activities of IL-5. Of note is that although the IL-5 deficient mice cannot elicit a pronounced eosinophilia in response to inflammatory stimulation following aeroallergen challenge or parasite infection they still produce basal levels of eosinophils that appear to be morphologically and functionally normal. However, the basal levels of eosinophils appear insufficient for normal host defense as IL-5 deficiency has now been shown to compromise defense against several helminth infections. In addition, IL-5 deficient mice appear to have functional deficiencies in B-1 B lymphocytes and in IgA production.

Animals↗
PubMed1996

Interleukin 5 deficiency abolishes eosinophilia, airways hyperreactivity, and lung damage in a mouse asthma model.

Airways inflammation is thought to play a central role in the pathogenesis of asthma. However, the precise role that individual inflammatory cells and mediators play in the development of airways hyperreactivity and the morphological changes of the lung during allergic pulmonary inflammation is unknown. In this investigation we have used a mouse model of allergic pulmonary inflammation and interleukin (IL) 5-deficient mice to establish the essential role of this cytokine and eosinophils in the initiation of aeroallergen-induced lung damage and the development of airways hyperreactivity. Sensitization and aerosol challenge of mice with ovalbumin results in airways eosinophilia and extensive lung damage analogous to that seen in asthma. Aeroallergen-challenged mice also display airways hyperreactivity to beta-methacholine. In IL-5-deficient mice, the eosinophilia, lung damage, and airways hyperreactivity normally resulting from aeroallergen challenge were abolished. Reconstitution of IL-5 production with recombinant vaccinia viruses engineered to express this factor completely restored aeroallergen-induced eosinophilia and airways dysfunction. These results indicate that IL-5 and eosinophils are central mediators in the pathogenesis of allergic lung disease.

Aerosols↗
PubMed1996

IL-5-deficient mice have a developmental defect in CD5+ B-1 cells and lack eosinophilia but have normal antibody and cytotoxic T cell responses.

Mice deficient in interleukin-5 (IL-5-/- mice) were generated by gene targeting in embryonal stem cells. Contrary to previous studies, no obligatory role for IL-5 was demonstrated in the regulation of conventional B (B-2) cells, in normal T cell-dependent antibody responses or in cytotoxic T cell development. However, CD5+ B cells (B-1 cells) in the peritoneal cavity were reduced by 50%-80% in 2-week-old IL-5-/- mice, returning to normal by 6-8 weeks of age. The IL-5-/- mice did not develop blood and tissue eosinophilia when infected with the helminth Mesocestoides corti, but basal levels of eosinophils with normal morphology were produced in the absence of IL-5. IL-5 deficiency did not affect the worm burden of infected mice, indicating that increased eosinophils do not play a significant role in the host defence in this parasite model.

Animals↗
PubMed1995

Exclusion of defects in the skeletal muscle specific regions of the DHPR alpha 1 subunit as frequent causes of malignant hyperthermia.

The molecular defect predisposing to the majority of malignant hyperthermia (MH) cases is unknown, although various point mutations in the ryanodine receptor gene (RYR1) have been associated with susceptibility in a small proportion of cases. We report here that one of these, the Arg163Cys substitution, does not cosegregate with MH susceptibility. Comparison of cDNA sequences encoding the skeletal muscle specific components of the dihydropyridine receptor alpha 1 subunit between MH susceptible (MHS) and MH non-susceptible (MHN) patients was made in subjects without the reported MH linked RYR1 mutations. There were no differences within the sequence encoding the II-III loop or the IS3/IS3-IS4 segment, excluding defects in these functional segments of the alpha 1 subunit as frequent causes of MH.

Base Sequence↗
PubMed1994

The role of interleukin-6 in mucosal IgA antibody responses in vivo.

In mice with targeted disruption of the gene that encodes interleukin-6 (IL-6), greatly reduced numbers of immunoglobulin A (IgA)-producing cells were observed at mucosae and grossly deficient local antibody responses were recorded after mucosal challenge with either ovalbumin or vaccinia virus. The IgA response in the lungs was completely restored after intranasal infection with recombinant vaccinia viruses engineered to express IL-6. These findings demonstrate a critical role for IL-6 in vivo in the development of local IgA antibody responses and illustrate the effectiveness of vector-directed cytokine gene therapy.

Animals↗
PubMed1991

Association of exogenous DNA with cattle and insect spermatozoa in vitro.

Spermatozoa isolated from domestic cattle (Bos taurus), the Australian sheep blowfly (Lucilia cuprina), and the honeybee (Apis mellifera) are capable of binding exogenous radiolabeled linear DNA. Both motile and nonmotile bovine sperm exhibit four distinct patterns of DNA association. Following treatment with DNase I, the relative proportion of one of these patterns increases specifically in living sperm, suggesting that a small proportion of DNA that associates with bovine sperm may be sequestered within the sperm head.

Animals↗
PubMed1989

Occurrence of the (GATA)n sequences in vertebrate and invertebrate genomes.

Clusters of the tetranucleotide GATA are found throughout the mouse genome with a major concentration on the Y chromosome. In Drosophila melanogaster, by contrast, they have a significant concentration on the X chromosome. Largely on the basis of these sex chromosomal concentrations and on their transcriptional activity in the mouse, these simple sequence tracts have been thought to be important in sex-determining and X inactivation mechanisms in both vertebrates and invertebrates. In every tested case the interpretations of the data have been difficult and sometimes the data themselves have been conflicting. We demonstrate in this paper that significant tracts of (GATA)n are totally absent from ovine and bovine genomes and point out that none of the major clusters of these repetitive sequences are near any of the sex-determining genes in D. melanogaster. We conclude therefore that (GATA)n sequences are not conserved over long evolutionary time periods as has previously been thought. Their absence from at least two mammalian genomes places severe constraints on their possible functions.

Animals↗
PubMed1987

Ornithine aminotransferase turnover in host tissues of tumor-bearing rats.

The activity of ornithine-oxo-acid aminotransferase (OAT) in the liver and kidneys of rats was notably decreased as a consequence of tumor bearing. The decrease in the activity of OAT was closely related to a concomitant decrease in the rate of synthesis of the enzyme in both host tissues, while the rate of enzyme degradation remained unchanged. These results are concluded to be consistent with the proposal that host tissues of tumor-bearing animals may become "dedifferentiated," and in this example the mechanism of the expression of the dedifferentiation involved the significant decrease in specific enzyme production.

Animals↗
PubMed1983

Differentiation-defective mutants of mouse embryonal carcinoma cells: response to hexamethylenebisacetamide and retinoic acid.

We have generated by mutagenesis eight differentiation-defective sublines from three murine embryonal carcinoma (EC) cell lines. These mutants grossly resemble parental cells in the absence of inducers of differentiation. Based upon response to retinoic acid (RA) or hexamethylenebisacetamide (HMBA), the mutants can be grouped into three types: (a) RA-selected cells that lack cellular RA binding protein (cRABP) activity and fail to differentiate in response to RA or HMBA; (b) RA- or HMBA-selected cells that possess cRABP but differentiate poorly, if at all, in the presence of RA or HMBA; and (c) cells originally selected for lack of response to HMBA but which retain cRABP and the ability to differentiate in response to RA.

Acetamides↗
PubMed1983

Retinoid binding protein activities in murine embryonal carcinoma cells and their differentiated derivatives.

It has been proposed that cellular retinoic acid binding protein is essential for retinoid-induced differentiation of embryonal carcinoma line PCC4.aza1R. To assess the generality of this proposal, we have tested for the presence of cellular retinoic acid binding protein activities in several other embryonal carcinoma lines. Cytosolic extracts from all cells were found to possess binding proteins for retinoic acid and also for retinol, although levels varied widely among the different lines. There was no clear quantitative relationship between binding protein activities and the propensity of the cells for differentiation in tumor form or under various in vitro conditions. Our results suggest that other factors might modulate the response of embryonal carcinoma cells to retinoids and/or that alternate pathways for differentiation which do not involve retinoids and retinoid binding proteins exist in these cells. When embryonal carcinoma cells are stimulated to differentiate, the derivatives can possess higher, lower, or similar levels of retinoic acid binding protein activity. These levels appear to reflect the phenotype of the differentiated cells rather than the conversion from a tumorigenic to a nontumorigenic state.

Animals↗
PubMed1981

Studies on the mechanism of induction of embryonal carcinoma cell differentiation by retinoic acid.

On the basis of our studies, we conclude that RA is a potent promoter of differentiation of EC cells. We have demonstrated that the tumorigenicity of PCC4-azalR EC cultures can be effectively reduced following exposure of the cells to RA. This is presumably a result of differentiation of the EC cells to nontumorigenic derivatives. However, even after several weeks of exposure to RA, there remains in the culture a subpopulation of unresponsive EC cells. The reason why these cells do not differentiate in the presence of RA is currently under investigation. We have also derived by mutagen treatment and clonal selection EC cells that fail to respond to RA. Preliminary indications are that these cells have lost the capacity to differentiate when subjected to other manipulations which stimulate differentiation of the parental EC cells. This is an important observation since the mutants were selected only by their lack of response to RA. Unlike the parental cells, which have relatively large amounts of RABP, dif- cells appear either to lack RABP or to possess an altered binding protein which has a greatly reduced affinity for RA. These observations are consistent with the view that some function of the RA-RABP complex is critical in the sequence of events leading to differentiation of EC cells. However, further studies are required before we can establish the generality of this proposal. We are presently investigating whether the level and/or function of RA-RABP complexes in cells from the EC lines listed in TABLE 1 can explain their varying tendencies to differentiate.

Animals↗
PubMed1981

Isolation and characterization of mouse mutant embryonal carcinoma cells which fail to differentiate in response to retinoic acid.

Murine embryonal carcinoma cells from line PCC4.aza1R differentiate readily in response to retinoic acid. By treating PCC4.aza1R cells with the mutagen N-methyl-N' -nitro-N-nitrosoguanidine, we derived two embryonal carcinoma lines in which the cells failed to differentiate during exposure to retinoic acid. Although these dif(RA)- cells maintained the tumorigenic potential of the parental cells, they differentiated poorly in tumor form. Similarly, the tendency of dif(RA)- cells to differentiate when aggregated in vitro was diminished relative to that of PCC4.zaz1R cells. The rate of retinoic acid uptake in cells from the two mutant lines did not appear to be reduced compared with the rate in cells from the parental line; however, specific cytoplasmic retinoic acid-binding protein activity was virtually absent in both mutants. These results strengthen the view that differentiation of embryonal carcinoma cells in response to retinoic acid requires formation of retinoic acid-cytoplasmic retinoic acid-binding protein complexes.

Animals↗