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Biomedical subjects

D H Dean

Publications and source records attributed to D H Dean.

At least 91 records · Page 5Linked to original sources
PubMed1984

Reorienting and expanding the physical map of temperate Bacillus subtilis bacteriophage phi 105.

During the course of extending the physical map of Bacillus subtilis temperate bacteriophage phi 105 to include SstI, XhoI, and HpaI, we recognized that the previous physical map for EcoRI was incorrect. The new enzyme maps were determined by single, double, and partial enzyme digestions, redigestion of purified phage fragments, end joint analysis, and DNA-DNA hybridization. The EcoRI physical map was corrected by double digestion of isolated fragments, DNA hybridization, and physical mapping by partial digestion of end-labeled fragments. EcoRI fragment G was repositioned to give the order D-G-I-E-B-H-F-C.

Bacillus subtilis↗
PubMed1984

Decreased plasma testosterone and total thyroxine in desalivated male rats.

Plasma testosterone and total thyroxine were decreased by 50 and 35%, respectively, in submandibular gland extirpated or parotid duct ligated rats treated 27 days earlier. Sixty-two days after surgery, testosterone and total thyroxine were decreased by 20 and 40%, respectively. These changes occurred in the absence of evidence of nutritional impairment or signs of stress, such as adrenal enlargement or thymic involution.

Animals↗
PubMed1983

Similarity of genetic distance determined from DNA thermal denaturation profiles to standard estimates of bacteriophage relatedness.

High resolution thermal denaturation profiles of a series of potentially related bacteriophages of Bacillus subtilis contain a multitude of distinctive features that permit them to be divided into at least four groups. In addition, the profiles can be used to derive the quantitative parameter, genetic distance, defined by Soumpasis (Soumpasis, D. (1980) J. Theor. Biol. 86, 137-147). Both the quantitative and the qualitative intercomparisons of profiles are in general agreement with the results of standard techniques for estimating genetic relatedness.

Bacillus subtilis↗
PubMed1983

Transfection of Bacillus subtilis protoplasts by bacteriophage phi do7 DNA.

DNA from the Bacillus subtilis temperate bacteriophage phi do7 was found to efficiently transfect B. subtilis protoplasts; protoplast transfection was more efficient than competent cell transfection by a magnitude of 10(3). Unlike competent cell transfection, protoplast transfection did not require primary recombination, suggesting that phi do7 DNA enters the protoplast as double-stranded molecules.

Bacillus subtilis↗
PubMed1981

A genetic engineering manifesto for the genus Bacillus.

The genus Bacillus is widely studied in industry and academia because of the secretion of enzymes and antibiotics. Genetic manipulation is available in several species and genetic engineering capabilities are presently developed or under construction. Bacteriophage cloning vehicles are available which facilitate isolation and selection of individual genes and plasmid cloning vehicles are available for amplification of genes and gene products. The application of these techniques to industrially important genes is just beginning in Bacillus and continued genetic engineering in this genus promises to enhance production of numerous products in the near future.

Anti-Bacterial Agents↗
PubMed1981

Transformation of Bacillus thuringiensis protoplasts by plasmid deoxyribonucleic acid.

A method has been developed to transform plasmid deoxyribonucleic acid into protoplasts of the insect pathogen Bacillus thuringiensis. Protoplasts were formed by treatment of cells with lysozyme. The efficiency of formation of protoplasts was affected by the strain, the media, and the cell density. Deoxyribonucleic acid uptake was induced by polyethylene glycol. Deoxyribonucleic acid from the Staphylococcus aureus plasmid pC194 was used for transformation. Although this plasmid could not be isolated as a stable extrachromosomal element, its chloramphenicol resistance was transferred to the recipient protoplasts. This was confirmed by assay for the enzyme chloramphenicol acetyltransferase, which confers resistance to chloramphenicol. This suggested that pC194 acts as an insertion element in B. thuringiensis.

Acetyltransferases↗
PubMed1980

Physical mapping of Bacillus subtilis phage rho14 cloning vehicles: heteroduplex and restriction enzyme analyses.

Four deletion mutants of temperate Bacillus subtilis bacteriophage rho14 have been examined utilizing restriction enzyme and DNA heteroduplex methods. This has allowed the orientation and mapping of the deletions on the rho14 physical map. A continuous 15% of the genome contains functions not essential for bacteriophage viability. A 7% subsection of this region contains phage immunity functions. The deletions were found to range in size from about 2.2-3.3 kilobases. In addition, the deletion mutants retain a single Sal I restriction site, which is currently being used as a cloning site for recombinant DNA. We have located the Sal I site to be 400 basepairs from the immunity region. Thus, the clear- and turbid-plaque deletion mutants are all capable of being utilized as molecular cloning vehicles for Bacillus subtilis.

Bacillus subtilis↗
PubMed1978

Restriction endonuclease mapping of bacteriophage phi105 and closely related temperate Bacillus subtilis bacteriophages rho10 and rho14.

Cleavage maps of the three similar Bacillus subtilis temperate bacteriophages, phi105, rho10, and rho14, were constructed by partial digestion analysis utilizing the restriction endonuclease EcoRI. Comparison of the topography of these maps indicates that all phage DNAs posses cohesive ends and a number of EcoRI restriction sites; the fragments are conserved, and the estimated base substitution/nucleotide divergence between these phages is 0.03 to 0.07 based on conserved fragments or between 0.03 and 0.11 based on conserved cleavage sites. These lines of evidence indicate that phi105, rho10, and rho14 are closely related. Double-enzyme digestion analysis reveals that rho14 DNA has unique SalGI and BglII restriction sites and phi105 DNA has a unique SalGI restriction site, making these phages possible cloning vectors for B. subtilis.

Bacillus subtilis↗
PubMed1977

Fragmentation of Bacillus bacteriophage phi105 DNA by complementary single-stranded DNA in the cohesive ends of the molecule.

The structure of DNA from the temperate Bacillus subtilis phage phi105 was examined by using the restriction endonuclease EcoRI and by sedimentation analysis. The DNA contains six EcoRI cleavage sites. Although eight DNA fragments were identified in the EcoRI digests, the largest of these was shown to consist of the two fragments that carry the cohesive ends of the phage DNA. In neutral gradients, the majority of whole phi105 DNA sedimented as nicked circles and the remainder as oligomers. No unit-length linear structures were detected. The associated cohesive ends could be sealed by DNA ligase from Escherichia coli and could be cleaved by S1 nuclease. On the basis of these results and previously reported studies, it appears that, as isolated from phage particles, phi105 DNA is a circular molecule that is formed from the linear structure by the association of complementary single-stranded DNA.

Bacillus subtilis↗
PubMed1976

Population cancer screening.

Controlled trials to evaluate mass screening programs for cancer detection have been singularly lacking. High cost, lack of medical manpower, and low yield have contributed to this problem. A new program in cancer detection (CANSCREEN) has been developed jointly by The Fox Chase Cancer Center in Philadelphia and the Preventive Medicine Institute in New York City. This program attempts to provide a quality cancer-detection examination with increased cost effectiveness. Features include: 1) a self-administered questionnaire on medical history, symptoms, and risk factors; 2) nonphysican examiners; 3) risk-facotr analysis with a predetermined decision logic to determine type and periodicity of examination; and 4) primary intervention (health education). This collaborative program between two institutions in two cities demonstrates the feasibility of introducing similar programs elsewhere. A data base shared by cooperating centers permits information on all patients to be used for evaluation of new techniques, end results, etc. A randomized controlled trial has been designed to evaluate the effectiveness and efficiency of the questionnaire alone and of the questionnaire and examination.

Breast Neoplasms↗
PubMed1976

New temperate bacteriophage for Bacillus subtilis, rho 11.

A new temperate bacteriophage, rho11, isolated by J. Hoch, has been characterized. This new phage is very similar to the temperate phage phi3T in size (380 nm), host range, homoimmunity, DNA buoyant density (1.694 g/ml), antigenicity, and molecular weight (around 6.0 X 10(7)) as determined in gels. Like phi3T, rho11 converts thymine auxotrophs to prototrophy at high frequency (250 out of 250 tested). Phage rho11 differs from phi3T in plaque morphology and in the endonuclease R-EcoRI digest pattern. Sixteen of the 20 rho11 DNA fragments have migration patterns corresponding to those of the 21 fragments of phi3T. The close similarities yet clear differences between these phages suggest that the two phages have a common ancestor.

Bacillus subtilis↗