PubMed Health⌕ Search

Biomedical subjects

M Zoller

Publications and source records attributed to M Zoller.

29 records · Page 2Linked to original sources
PubMed1983

Transcription of plasmid DNA in Escherichia coli minicells.

Cellular RNA polymerase in association with plasmid DNA segregates into the minicells of minicell-producing strains. In general, one "plasmid equivalent" of RNA polymerase, reflecting the size of the segregating plasmid DNA and its efficiency of segregation, entered the minicell with the plasmid. The amount of RNA polymerase (measured as the amount of enzyme activity purified from minicells and the rate of RNA synthesis in plasmid-containing minicells), and not the DNA content, appeared to be rate-limiting in plasmid-mediated transcription in minicells. The purified minicell and cellular RNA polymerases showed the same sensitivity to rifampin and streptolydigin; both were associated with sigma factor, although the minicell enzyme appeared to have slightly less than the cellular enzyme. These studies demonstrate that transcription of plasmid DNA in minicells is a function of the efficiency of segregation and the amount of RNA polymerase which enters with the plasmid DNA. Because RNA polymerase is limiting, plasmids with relatively weak promoters for the vector genes should be used when attempting to identify products from inserted foreign DNA.

Aminoglycosides↗
PubMed1983

Deletions and single base pair changes in the yeast mating type locus that prevent homothallic mating type conversions.

Several cis-acting mutations that prevent homothallic mating type conversions in Saccharomyces cerevisiae have been examined. Deletions within the mating type (MAT) locus were obtained by selecting for survivors among homothallic MAT alpha cells carrying the rad52 mutation. The survivors were unable to switch mating type, even in RAD+ derivatives. The deletions varied in size from fewer than 50 to more than 750 base pairs. All of the deletions removed a Hha I site at the border between the alpha-specific sequences (Y alpha) and the adjacent Z region. We also examined several spontaneous inc mutations that prevent MAT switching. Two of these mutations were cloned in recombinant DNA plasmids and their sequences were determined. The MAT alpha-inc 3-7 mutation proved to have an altered Hha I site at the Y alpha/Z border, by virtue of a single base pair substitution G . C leads to A . T in the second base pair of the Z region (Z2). Restriction fragment analysis showed that two other independently isolated strains with MAT alpha-inc mutations had altered the same Hha I site. The MAT a-inc 4-28 mutation contains a single base pair substitution C . G leads to T . A at position Z6. A base pair difference at position Z11 in two MATa strains does not affect MATa conversions. We conclude that the region near the Y/Z border is essential for the efficient switching of MAT alleles and constitutes an enzyme recognition site for a specific nucleolytic cleavage of MAT DNA.

Base Composition↗
PubMed1978

Detection of syphilitic hearing loss.

Syphilis can cause sensorineural hearing loss that is potentially treatable. To determine the incidence of positive serological findings in patients with sensorineural hearing loss, the rapid plasma reagin card test (RPRCT) and the FTA-ABS test were performed in a study group composed of patients with sensorineural hearing loss of obscure origin. Of the 306 patients with sensorineural hearing loss, 20 (6.5%) demonstrated a positive FTA-ABS as compared with two of 100 (2%) of the control group. Considerable variation was found in the rate of the false-negative and the biological false-positive RPRCT as performed by our hospital and state laboratories when compared with the results of the FTA-ABS test. Syphilis should be considered in any patient with sensorineural hearing loss of obscure origin, despite a negative history for syphilis. The FTA-ABS is the preferred test to exclude hearing loss of syphilitic origin.

Adolescent↗
PubMed1978

Guidelines for prognosis in head and neck cancer with nodal metastasis.

Patients with squamous cell carcinoma of the head and neck with cervical node metastasis were studied retrospectively to delineate the prognostic significance of certain clinical and histologic parameters. The patients were divided into radiated and non-radiated groups for analysis purposes. A good prognosis was found in non-radiated patients with an active nodal plasmacytic inflammatory response. No prognostic information was obtainable in observing the inflammatory response of nodes altered by radiation effects. Extranodal spread of the tumor indicated a poor prognosis for radiated and non-radiated patients, being more significant in the non-radiated ones. Patients receiving preoperative radiation must be separated from non-radiated patients in evaluating host response parameters for prognostic purposes.

Adult↗
PubMed1976

Antigen and antibody purification by immunoadsorption: elimination of non-biospecifically bound proteins.

Immunoadsorption is a simple and effective method for purifying antigens and antibodies. The major interfering effect is non-biospecific binding, especially when crude preparations of antibodies or antigens are coupled to the matrix. In this paper various possibilities for eliminating these effects are compared and analysed. It was found that for antigen (AFP) purification pre-elution with a pH 10.0 buffer of high ionic strength (1.0 M) is effective. A major problem in purifying antibodies in the non-biospecific binding of IgG. This can be eliminated by using a non-biospecific immunoadsorbent column, where specific antibodies are not, or only weakly bound and IgG with irrelevant specificity but exhibiting high non-biospecific interaction is retained. This has been applied to preparation of sheep anti-pepsinogen II group protease antibodies.

Absorption↗
PubMedDate not supplied

Treatment of syphilitic hearing loss. Combined penicillin and steroid therapy in 29 patients.

Twenty-nine patients with presumed syphilitic hearing loss, either congenital or acquired, were treated on one or more occasions according to a three-month protocol using penicillin and prednisone. Changes in hearing were carefully followed during treatment and for at least one year thereafter. Of 58 ears studied in 29 patients, 19 demonstrated significant partial improvement in hearing during treatment. However, 11 ears returned to pretreatment hearing levels after therapy, and only 8 ears, or 15%, maintained the hearing gains one year later. Enhanced discrimination occurred more commonly than gains in pure tone threshold. Long-term alternate day prednisone therapy was required to sustain hearing improvement in a small number of patients.

Adult↗
PubMedDate not supplied

Electronystagmography in congenital and acquired syphilitic otitis.

This study is an analysis of the electronystagmogram (ENG) changes in 17 patients with luetic vestibular disease with early and late acquired syphilis and congenital syphilis. Vestibular disturbances occurred in 80% of patients with luetic otitis. Among these patients the ENG gives signs of peripheral rather than central vestibular injury, and reduced vestibular response to caloric stimulation is the most common finding. Congenital syphilis patients have the greatest dysfunction, both in degree of ENG changes and incidence of bilaterality. We found no correlation between FTA-ABS levels and the amount of hearing impairment or vestibular injury. Treatment with penicillin and steroids had a beneficial subjective effect upon the symptoms of vertigo in over half the patients.

Adult↗