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Biomedical subjects

D W Frank

Publications and source records attributed to D W Frank.

At least 73 records · Page 4Linked to original sources
PubMed1989

Differential regulation by iron of regA and toxA transcript accumulation in Pseudomonas aeruginosa.

Iron regulation of toxA and regA transcript accumulation was examined in Pseudomonas aeruginosa PA103 containing the regA gene on a multicopy plasmid. The patterns of transcript accumulation for toxA and regA were found to be positively correlated. Dot blot and Northern (RNA) blot analysis of total RNA isolated throughout the bacterial growth cycle indicated that multiple copies of the regA gene uncoupled iron repression of the first phase of transcript accumulation for both regA and toxA genes. However, regulation by iron of the second phase of transcript accumulation for each gene was unaffected by several regA gene copies. Total toxin production was increased in cells with multiple copies of regA grown in either low- or high-iron medium. Primer extension analysis of regA mRNA extracted from cells grown in high- and low-iron medium and examined at different points in the cell growth cycle supported the hypothesis that iron regulation of regA transcription occurs at the level of transcriptional initiation. Two start sites were shown for regA transcription at -164 and -75 base pairs from the ATG start codon. The differential regulation of regA transcript accumulation when regA is present in single or multiple copy and the mapping of independent start sites for regA mRNA support the evidence that regA transcription is directed by independently regulated promoter regions.

ADP Ribose Transferases↗
PubMed1988

Kinetics of toxA and regA mRNA accumulation in Pseudomonas aeruginosa.

DNA probes specific for an internal portion of the toxA and regA genes were used to examine the synthesis of mRNA during the growth cycle of P. aeruginosa PA103. RNA dot blot analysis revealed that in a low-iron growth medium, the synthesis of regA and toxA mRNA followed a biphasic expression pattern. Analysis of ADP-ribosyltransferase activity also indicated that an early and late phase of exotoxin A synthesis occurred. Utilizing an internal SalI probe, examination of the size distribution of the regA mRNA during the cell cycle indicated that a large transcript (T1) was present at early time points, followed by the appearance of a smaller transcript (T2) during late exponential to early stationary phase. An upstream AvaI regA probe was found to hybridize to the T1 transcript but not to the T2 transcript. The data indicate that at least two separate functional regA mRNA species were produced. Analysis of mRNA accumulation for the regA gene when cells were grown in high-iron medium provided additional evidence for two separately controlled transcripts being produced from the regA chromosomal locus. Both regA transcripts were correlated with exotoxin A transcription and production.

Blotting, Northern↗
PubMed1985

Surface antigens of Bordetella pertussis.

Bordetella pertussis and other Bordetella species cause respiratory infections in humans and in a variety of animals. Clinical isolates of B. pertussis have multiple virulence factors, several of which have been reported to induce protective immunity. Using cell surface iodination techniques and monoclonal antibody immunoblots we have identified several proteins which are exposed on the surface of B. pertussis cells, including the filamentous hemagglutinin and outer membrane proteins 91, 18, and 15. Protein 91 is unique to virulent B. pertussis strains. Antibodies to protein 18 are found in convalescent serum of both humans and mice recovering from infection with B. pertussis.

Antibodies, Monoclonal↗
PubMed1985

Role of exoenzyme S in chronic Pseudomonas aeruginosa lung infections.

Exoenzyme S is an extracellular ADP-ribosyltransferase enzyme produced by Pseudomonas aeruginosa. Mutants of Pseudomonas aeruginosa deficient in this enzyme have been shown to have reduced virulence in infections of burned mice. The contribution of exoenzyme S to the pathogenesis of chronic lung infections with this organism was evaluated by examining the incidence of exoenzyme S production by Pseudomonas aeruginosa strains isolated from cystic fibrosis patients and comparing an exoenzyme S deficient mutant and its exoenzyme S producing parent in a rat chronic lung infection model. Of 51 isolates examined, 43% produced detectable levels of exoenzyme S. While both the exoenzyme S deficient mutant and its parent strain were equally capable of colonizing and persisting in rat lungs, the exoenzyme S producing parent elicited a greater degree of lung damage. These data suggest that exoenzyme S contributes to the pathogenesis of chronic lung infections.

ADP Ribose Transferases↗
PubMed1985

Cell surface antigens of Bordetella pertussis.

Cell surface-specific radiolabelling techniques, monoclonal antibody analyses, and chemical and physical isolation of cell fractions were used to study the surface of B. pertussis cells. Four surface specific proteins were identified by radioiodination and monoclonal antibody techniques. These included the filamentous hemagglutinin (FHA), and three outer membrane proteins-OMP91, OMP18 and OMP15. Membrane blebs were isolated from culture supernatants and shown to contain LPSII, pertussis toxin (PT), FHA, OMP91, and OMP18, but not OMP15. The level of LPS I in blebs appeared to be reduced from the level in cell envelopes. Bleb fractions contained enzymatically active adenylate cyclase (AC), and biologically active dermonecrotic toxin (DNT) and PT. Blebs were also toxic for mice, even when heated to 80 degrees C for 30 minutes. To explain these data, we propose that membrane blebs comprise an effective toxin delivery system, and that the cell surface of B. pertussis is composed of at least two domains.

Adenylate Cyclase Toxin↗
PubMed1984

A 6-month dietary toxicity study of acidic sodium aluminium phosphate in beagle dogs.

Sodium aluminium phosphate [NaAl3H14(PO4)8. 4H2O], a leavening acid, was administered to groups of six male and six female beagle dogs at dietary concentrations of 0, 0.3, 1.0 or 3.0% for 6 months. No adverse treatment-related clinical signs were observed. There were no statistically significant differences in mean body weights between test and control groups at any of the weekly determinations. Weekly mean food consumption values of all male treated groups did not differ significantly from those of the control group at any stage of the study. Statistically significant reductions in food consumption occurred sporadically in all treated groups of female dogs. No significant absolute or relative organ-weight differences were found between any of the treated groups and their respective controls. Haematological, blood chemistry and urinalysis data showed no toxicologically significant trends. Histopathological examination revealed no changes considered to be related to treatment. Thus dietary administration of sodium aluminum phosphate for 6 months at concentrations of 3% or lower caused no significant toxicological effects in beagle dogs.

Aluminum↗
PubMed1984

Isolation and characterization of monoclonal antibodies to Bordetella pertussis.

Monoclonal antibodies to Bordetella pertussis were produced by fusion of mouse myeloma cells and spleen cells of immunized mice. Cell lines were examined for specific antibody production against several crude antigen preparations and lipopolysaccharide. Cross reactivity of monoclonal antibodies was assessed by enzyme immunoassay using cell lysates prepared from Bordetella spp. and several other bacteria. Reactivity of monoclonal antibodies to cell surface components was determined by immunofluorescence microscopy. Monoclonal antibodies represent useful probes to study the antigenic profile and distribution of antigens among various species of Bordetella, as well as specific tools to study the structure and function of B. pertussis virulence factors.

Animals↗
PubMed1984

Interaction of monoclonal antibodies with pertussis toxin and its subunits.

The binding of two monoclonal antibodies to crude and pure preparations of pertussis toxin was examined. Antibody P11B10 reacted with an epitope present on the S2 subunit of pertussis toxin by immunoblot techniques. Radioimmunoprecipitation analysis and immunoaffinity chromatography with P11B10 indicated that subunits S2 and S3 were closely associated. Antibody P7B10 was unreactive in immunoblots and radioimmunoprecipitation but was able to bind and retain toxin subunits during affinity chromatography. The P7B10 epitope may thus be labile to detergent treatment or radioiodination; or the epitope may form as a result of subunit association. Neither antibody alone nor both in combination neutralized the histamine-sensitizing activity of pertussis toxin in passive-transfer experiments. However, toxin isolated by immunoaffinity chromatography with either monoclonal antibody was able to sensitize mice to histamine challenge.

Antibodies, Bacterial↗
PubMed1979

Mammary tumors and serum hormones in the bitch treated with medroxyprogesterone acetate or progesterone for four years.

After 4 years of a long-term contraceptive steroid safety study, the incidence and the histologic types of mammary dysplasia produced are shown to be similar in beagles treated with medroxyprogesterone acetate (medroxyprogesterone) or progesterone. Serum insulin, thyroid-stimulating hormone (TSH), triiodothyronine, growth hormone, prolactin, 17 beta-estradiol, progesterone, and cortisol were determined by radioimmunoassay on samples collected after 45 months of treatment. Serum growth hormone and insulin concentrations were elevated in a dose-related manner in both treatment groups. Levels of triiodothyronine, cortisol, and 17 beta-estradiol (medroxyprogesterone only) were lowered. TSH and prolactin concentrations were not changed. Pituitary-gonadal hormone interaction in the pathogenesis of mammary neoplasia of the dog is discussed. Prolonged treatment of beagles with doses of progesterone or medroxyprogesterone 1 to 25 times the human contraceptive dose or luteal phase (dog) levels, respectively, results in a dose-related incidence of mammary nodules.

Adenoma↗
PubMed1978

A comparison of two methods for evaluating drug-induced chromosome alterations.

Evaluating the technique and procedure for mutagenicity testing in mammals is a prerequisite to the development of a broad spectrum mutagenic assessment program. Two techniques, chromosome examination and micronucleus scoring, show promise but their applicability for mass screening is uncertain. We determined the slide observation time for these two techniques in mice treated orally, subcutaneously, intravenously, and intraperitoneally with cyclophosphamide (CY). In each instance, we detected a dose-response in less observation time by counting micronuclei in polychromatophilic erythrocytes. The simplicity of the scoring method, the ease of micronucleus identification and the rapidity of scoring all suggest the micronucleus test may be favorably integrated into a mutagenicity screening program.

Animals↗
PubMed1976

Cyclodextrin nephrosis in the rat.

The renal toxicity of the Schardinger dextrins, alpha and beta-cyclodextrin, is manifested as a series of alterations in the vacuolar organelles of the proximal convoluted tubule. These changes begin as an increase of apical vacuoles and the appearance of giant lysosomes. The giant lysosomes characteristic of cyclodextrin nephrosis are notable because of the prominent acicular microcrystals embedded in the lysosomal matrix. Giant vacuoles devoid of acid phosphatase reaction product are found in advanced lesions. The vacuolar apparatus shows advanced changes prior to manifestation of lesions in mitochondria and other organelles. These observations indicate a role of the vacuologenic apparatus in the nephrotic process. Intracellular concentration of toxin via the lysosomal pathway represents a perversion of the physiologic function of the proximal tubule which ultimately leads to cell death.

Animals↗