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Biomedical subjects

M Gold

Publications and source records attributed to M Gold.

At least 181 records · Page 10Linked to original sources
PubMed1987

The control of lambda DNA terminase synthesis.

Nu1 and A, the genes coding for bacteriophage lambda DNA terminase, rank among the most poorly translated genes expressed in E. coli. To understand the reason for this low level of translation the genes were cloned into plasmids and their expression measured. In addition, the wild type DNA sequences immediately preceding the genes were reduced and modified. It was found that the elements that control translation are contained in the 100 base pairs upstream from the initiation codon. Interchanging these upstream sequences with those of an efficiently translated gene dramatically increased the translation of terminase subunits. It seems unlikely that the rare codons present in the genes, and any feature of their mRNA secondary structure play a role in the control of their translation. The elimination of cos from plasmids containing Nu1 and A also resulted in an increase in terminase production. This result suggests a role for cos in the control of late gene expression. The terminase subunit overproducer strains are potentially very useful for the design of improved DNA packaging and cosmid mapping techniques.

Bacteriophage lambda↗
PubMed1987

A novel in vitro DNA packaging system demonstrating a direct role for the bacteriophage lambda FI gene product.

A new in vitro bacteriophage lambda DNA packaging system is described in which all the proteins necessary for head morphogenesis are supplied by extracts of plasmid-transformed cells. This assay is used to demonstrate that the lambda FI gene product (gpFI) is necessary for maximal packaging efficiency when proheads and terminase are present in limiting amounts. A 100- to 200-fold decrease in packaging is seen when gpFI is omitted. gpFI is shown to act at and/or after the stage in packaging where proheads bind to the DNA:terminase complex.

Bacteriophage lambda↗
PubMed1987

Enkephalinase inhibitors potentiate substance P-induced secretion of 35SO4-macromolecules from ferret trachea.

To study the roles of substance P (SP) and endogenous peptidases in regulating mucus secretion from ferret trachea, we measured the SP-induced release of 35SO4-labeled macromolecules after incubating segments of trachea in Ussing chambers in the presence and absence of selected inhibitors of proteolytic enzymes. Our strategy was based on the idea that if endogenous peptidases degrade SP, then inhibitors of these enzymes should potentiate SP-induced secretion. We found that tracheas of ferrets contained SP-like immunoreactivity, and that SP stimulated the release of bound 35SO4 with rapid onset and offset. Eighty-five percent of the total macromolecular radioactivity released was contained in fractions of molecular weights greater than 10(6). The response to SP was concentration-dependent and reproducible. Thiorphan potentiated the secretory response to SP in a concentration-dependent fashion and phosphoramidon potentiated SP-induced secretion, whereas other inhibitors of proteinases and peptidases were without effects. These results suggest that substance P may regulate mucus secretion in ferrets, and that enkephalinase (dipeptidyl carboxypeptidase II, EC 3.4.24.11) in the airway degrades SP in a physiologically significant fashion, and thereby regulates peptide-induced secretion.

Animals↗
PubMed1986

A bacterial protein requirement for the bacteriophage lambda terminase reaction.

The bacteriophage lambda terminase enzyme cleaves the cohesive-end sites of lambda DNA to yield the protruding 5'-termini of the mature molecule. In vitro, this endonucleolytic event requires a protein factor which has been isolated and purified from extracts of uninfected E. coli. The terminase host factor (THF) is a heat stable basic protein of M.W. approximately 22,000. The integration host factor (IHF) protein of E. coli can efficiently substitute for THF in the terminase reaction; however, THF can be demonstrated to be physically present in, and isolated with full biological activity from extracts of cells defective or deficient in IHF.

Bacterial Proteins↗
PubMed1986

Comparison of novice and experienced pilots using analog and digital flight displays.

Using 2 computer generated flight displays, 38 flight-naive persons and 18 experienced pilots were taught to perform 5 basic flight maneuvers. One display type used analog tapes to display the flight parameters while the other used digits. After learning to perform the maneuvers to the preset criteria using each of the display types, the subjects had to perform the same maneuvers to the same criterion level with the same displays while performing an aural side task. Overall, the digital displays were more difficult to learn to fly with than the analog displays, and the analog displays resulted in superior performances while under side task loading.

Aerospace Medicine↗
PubMed1984

The accuracy of self-reported regulatory data: the case of coal mine dust.

Coal-mine owners are required to measure miner exposures to respirable dust so that compliance with Federal health regulations can be monitored. This study analyzes the problem of possible underreporting of dust exposures. Using two statistical approaches, data for three mining occupations in 54 large underground coal mines during 1976-1978 are examined for evidence of underreporting. First, regression estimates compare dust concentrations reported by coal-mine owners with those reported by government health inspectors. Then, the statistical distribution of concentrations reported by coal-mine owners are examined for the size and nature of their deviation from log-normality. Both approaches suggest widespread underreporting.

Air Pollutants, Occupational↗
PubMed1984

The demand for hospital outpatient services.

In an investigation of the role played by hospital outpatient services in medical care delivery, objectives were to identify the factors which influence the demand for these services; and to determine the relationship between outpatient service volume and the availability and price of alternative sources of care, particularly office-based physicians and hospital inpatient services. Data were from a merged national data set containing population, socioeconomic, health services, manpower supply, and cost information. Two methods were used to examine demand for hospital outpatient services. The first replicated the earlier work by Davis and Russell using more recent (1978 versus 1969) and more geographically defined (Health Service Area versus state) data. The second extended this work, using the improved availability of data to estimate demand equations, distinguishing between emergency room and other outpatient visits. The results confirmed and extended the findings of earlier efforts. The level of hospital outpatient services appears related both to the availability and the price of other sources of care, as well as to insurance coverage and other factors. These findings have implications for reform of hospital outpatient reimbursement, for cost containment under Medicaid, and in related areas.

Catchment Area, Health↗
PubMed1983

The bacteriophage lambda terminase. Partial purification and preliminary characterization of properties.

The maturation of bacteriophage lambda DNA and its packaging into preformed heads to produce infectious phage is under the control of the two leftmost genes on the lambda chromosome, i.e., Nu1 and A. Based on its ability to complement lambda A- phage-infected cell extracts for packaging of lambda DNA in vitro, a single protein, designated terminase (ter) has been extensively purified using adsorption, ion exchange, and affinity column chromatography. The final preparation represents an approximately 60,000-fold purification over the activity found in crude extracts and is about 30 to 80% homogeneous as judged by visualizing the protein after electrophoresis in sodium dodecyl sulfate-polyacrylamide gel. In addition to packaging, terminase can also catalyze the endonucleolytic cleavage of lambda cohesive-end site DNA; both of these reactions require ATP. In some preparations, certain terminase fractions of extreme purity require protein factors present in extracts of uninfected Escherichia coli in order to catalyze the cohesive-end site cleavage reaction. On ion exchange columns purified terminase co-chromatographs with a DNA-dependent ATPase activity, hydrolyzing ATP to ADP and Pi in the presence of any of several types of DNA tested including those of non-lambda origin. The molecular weight of the native enzyme is 117,000 and appears to be a hetero-oligomer composed of 2 nonidentical subunits. The most likely composition of terminase is one gpA (gene product of A), Mr = 74,000 and two gpNu1, Mr = 21,000.

Adenosine Triphosphatases↗