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Biomedical subjects

M A Hauser

Publications and source records attributed to M A Hauser.

8 recordsLinked to original sources
PubMed1995

Expression of full-length and truncated dystrophin mini-genes in transgenic mdx mice.

Duchenne and Becker muscular dystrophy are caused by defects in the dystrophin gene, and are candidates for treatment by gene therapy. We have shown previously that overexpression of a full-length dystrophin cDNA prevents the development of dystrophic symptoms in mdx mice. We show here that this functional correction can be achieved by expressing the full-length muscle isoform at a lower level than is present in control animals. Gene therapy for DMD may necessitate the use of truncated dystrophin mini-genes to accommodate the limited cloning capacity of current-generation viral delivery vectors. We have constructed both murine and human mini-genes deleted for exons 17-48, and have demonstrated that expression of either mini-gene can almost completely prevent the development of dystrophic symptoms in transgenic mdx mice. These results suggest that viral-mediated expression of moderate levels of a truncated dystrophin could be an effective treatment for DMD.

Animals↗
PubMed1992

Site-specific integration of the Haemophilus influenzae bacteriophage HP1. Identification of the points of recombinational strand exchange and the limits of the host attachment site.

Isotopic transfer experiments and boundary replacement studies were used to define the size and cleavage points of the Haemophilus influenzae attB site for phage HP1 integration. The points of strand cleavage and transfer were separated by 5' extensions with a spacing or overlap region most probably 7 residues long. The complete HP1 attB site is included within an 18-base pair (bp) sequence surrounding the cleavage sites. The sequence of HP1 attB is remarkably symmetric. Two 8-bp inverted repeats surround the central residue of the 7-bp overlap sequence; this central residue is the second residue of the anticodon sequence of the H. influenzae tRNA(leu)(UUR) gene which contains attB, and this symmetric segment encodes the anticodon stem and loop.

Anticodon↗
PubMed1992

Site-specific integration of the Haemophilus influenzae bacteriophage HP1: location of the boundaries of the phage attachment site.

Plasmids containing DNA segments from the attachment region of phage HP1 were constructed and tested for the ability to replace the phage attachment site substrate in site-specific recombination reactions. The distance separating the boundaries of the functional site was 418 bp. Replacements within the 11-residue segment 5'-GGCGGTTATCG at the left boundary or within the 12-residue segment 5'-GGATTTTTTGAA at the right boundary abolished substrate activity. A segment of the 418-residue sequence preserves the integrity of an operon of three Haemophilus influenzae tRNA genes after HP1 insertion within the coding sequence.

Attachment Sites, Microbiological↗
PubMed1991

Plasmids for recombination-based screening.

To facilitate recombination-based screening, we constructed the ColE1-based plasmid, pi G4, that confers chloramphenicol resistance, contains a polylinker with multiple unique restriction enzyme recognition sequences, and contains the genetic marker, supF. To facilitate recombination-based screening followed by rapid DNA sequencing, we inserted the selectable marker, supF, into each of 20 high-copy-number (hcn) pUC-derived NoC plasmids that were designed for multiplex DNA sequencing. To facilitate recombination-based screening of common cDNA libraries that often contain ColE1 sequences, we constructed a supF-carrying plasmid whose replication was driven from an R6K replicon that does not share sequence homology with ColE1. Furthermore, we incorporated a useful polylinker and increased the copy number of this plasmid to create the 4.4-kb hcn plasmid, pMAD1. Thus, these plasmids allow: (1) background-free transformation of cells by a supF plasmid carrying an antibiotic-resistance marker; (2) simultaneous performance of the recombination-based assay and DNA sequencing; and (3) screening bacteriophage cDNA libraries that contain ColE1 sequences by recombination with a supF plasmid that is not homologous to ColE1 derivatives.

Bacteriophage lambda↗
PubMed1986

Variation of neutrophil function with age in calves.

Neutrophil function was evaluated on 2 occasions in 5 calves from each of the following age groups: 4 to 5 weeks, 9 to 11 weeks, 16 to 19 weeks, and 12 to 14 months. Of the neutrophil functions examined, the iodination reaction, which evaluates the activity of the myeloperoxidase-hydrogen peroxide-halide antibacterial system of the neutrophil, reflected the most marked differences among age groups. The iodination values for the 2 youngest age groups were approximately 52% of the value for the oldest cattle. This difference could not be attributed to the amount of myeloperoxidase in the neutrophil granules. Antibody-dependent cell-mediated cytotoxicity also tended to be lower in neutrophils from the 3 younger age groups. Nitroblue tetrazolium reduction, a measure of superoxide anion generation by neutrophils, was lower in the youngest age group only. The capability of neutrophils to ingest Staphylococcus aureus was higher in the 3 youngest groups of calves than in the oldest group. The observed differences in neutrophil function in young vs older calves may be partially responsible for the increased susceptibility of young calves to infectious disease.

Aging↗