Penn Dental Medicine

Established in 1878, Penn Dental Medicine is among the oldest university-affiliated dental schools in the nation. The school's mission is to transform global oral health and well-being through exceptional clinical care, innovation, education, and research.

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Now showing 1 - 4 of 4
  • Publication
    Transformation of the Cyanobacterium Anacystis Nidulans 6301 with the Escherichia Coli Plasmid pBR322
    (1986-04-01) Daniell, Henry; McFadden, B. A.
    Anacystis nidulans 6301 has been transformed in the light to ampicillin resistance with the plasmid pBR322. Permeaplasts prepared by 2-hr treatment of cells with lysozyme and EDTA are transformed with a 50-fold higher efficiency than that observed for cells. beta-Lactamase is present in A. nidulans transformed either with pBR322 or the plasmid pCH1 as evidenced by hydrolysis of the beta-lactam ring of Nitrocefin in extracts of transformants. beta-Lactamase also can be immunoprecipitated from extracts of [35S]methionine-labeled pBR322 transformants and coprecipitates with ribulose-bisphosphate carboxylase. Expression of the carboxylase is apparently amplified in pBR322 transformants as is that for several soluble proteins in pCH1 transformants. Chromosomal DNA per cell is increased about 6-fold after transformation of A. nidulans 6301 with either pBR322 or pCH1. A 4.3-kilobase-pair plasmid can be isolated from pBR322 transformants in addition to the endogenous plasmids pUH24 and pUH25.
  • Publication
    Intra-Oral Colonization of Macaque Monkeys by Actinobacillus Actinomycetemcomitans
    (1989-03-01) Beighton, David; Taichman, Norton S.; Simpson, David L.; Dirienzo, Joseph M.; Johnson, Newell
    Actinobacillus actinomycetemcomitans was acquired by captive Macaca fascicularis 3 to 6 months after birth, and all monkeys aged over 6 months harbored detectable levels. This microorganism was most frequently isolated from the gingival plaque of the incisor (and other) teeth compared with other oral sites. Strains were leukotoxic by bioassay and Western blot analysis. Antibodies in macaque serum contained neutralized the leukotoxin of a human A. actinomycetemcomitans strain. High titres of maternal neutralizing anti-leukotoxin antibodies were detected in neonates; the titre then fell rapidly so that by 6 months the antibody titer was zero. Antileukotoxin antibody production was detected after 6 months of age, rapidly reaching a high level within 2 years after birth. The presence of leukotoxic strains of A. actinomycetemcomitans in the gingival region did not appear to be correlated with an increase in susceptibility to periodontal disease.
  • Publication
    Studies on Histamine Secretion From Enzymically Dispersed Cutaneous Mast Cells of the Rat.
    (1985) Barrett, Kim E; Ali, Hydar; Pearce, Frederick L
    A method has been developed for the enzymic dissociation of rat skin into its component cells. The resulting suspensions contained 3–5% mast cells. The latter were intact as judged by light microscopy and exhibited a low spontaneous release of histamine. Cells obtained from actively sensitized animals released histamine on challenge with specific antigen. The process was rapid, being essentially complete within 1 mm and was both calcium-and temperature-dependent. The cells also responded to antirat IgE and to calcium ionophores but showed a selective, time-dependent reactivity toward defined chemical histamine liberators. On the basis of these results the properties of the cutaneous mast cell are compared with those previously reported for mastocytes from other sources and discussed in terms of the general heterogeneity of this cell population.
  • Publication
    Isolation of a Major Cell Envelope Protein from Fusobacterium Nucleatum
    (1984-05-01) DiRienzo, J. M.; Rosan, B.
    A major, heat-modifiable cell envelope protein was identified in Fusobacterium nucleatum FDC 364 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This protein, designated HM-1, had apparent molecular weights of 38,500 and 50,000 when heated in sodium dodecyl sulfate at 50 and 100 degrees C, respectively. Whole cells were labeled with 125I, and the results suggested that the HM-1 protein may be exposed on the bacterial surface. The HM-1 protein was isolated in association with the peptidoglycan by extraction of whole cells or cell envelopes with 2% sodium dodecyl sulfate at 55 degrees C. Heating the peptidoglycan-HM-1 protein complex in the detergent at 100 degrees C resulted in the quantitative release of the protein. Isoelectric focusing experiments and amino acid analysis revealed that the HM-1 protein had a basic character and was moderately hydrophilic. Various strains of F. nucleatum as well as three oral fusiform isolates contained a serologically related protein. The abundance and location of the HM-1 protein in F. nucleatum suggest that it has the potential to participate in cell surface-related interactions of this bacterium.