PubMed · 13797249
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
L C BARTLETT, P WARNER, H C MAZERALL. 1959. Notes on aseptic techniques.. https://pubmed.ncbi.nlm.nih.gov/13797249/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
BACKGROUND AND OBJECTIVES: It is established that both pulsed Nd:YAG (1,064 nm) and continuous diode (810 nm) dental lasers kill pathogenic bacteria (laser antisepsis), but a quantitative method for determining clinical dosimetry does not exist. The purpose of this study was to develop a method to quantify the efficacy of ablation of Porphyromonas gingivalis (Pg) in vitro for two different lasers. STUDY DESIGN/MATERIALS AND METHODS: The ablation thresholds for the two lasers were compared in the following manner. The energy density was measured as a function of distance from the output of the fiber-optic delivery system. Pg cultures were grown on blood agar plates under standard anaerobic conditions. Blood agar provides an approximation of gingival tissue for the wavelengths tested in having hemoglobin as a primary absorber. Single pulses of laser energy were delivered to Pg colonies and the energy density was increased until the appearance of a small plume was observed coincident with a laser pulse. The energy density at this point defines the ablation threshold. Ablation thresholds to a single pulse were determined for both Pg and for blood agar alone. RESULTS: The large difference in ablation thresholds between the pigmented pathogen and the host matrix for pulsed-Nd:YAG represented a significant therapeutic ratio and Pg was ablated without visible effect on the blood agar. Near threshold the 810-nm diode laser destroyed both the pathogen and the gel. CONCLUSIONS: Clinically, the pulsed Nd:YAG may selectively destroy pigmented pathogens leaving the surrounding tissue intact. The 810-nm diode laser may not demonstrate this selectivity due to its greater absorption by hemoglobin and/or longer pulse duration.
Neurosurgery for the removal of brain tumours based on localising signs is usually dated from the 1884 operation by Bennett and Godlee. However, within weeks of that operation claims were made on behalf of William Macewen, the Glasgow surgeon, to have been the real pioneer of such surgery. According to Macewen's protagonists, he had conducted seven similar operations earlier than Bennett and Godlee and, in a notable 1888 address, Macewen described these seven pre-1884 cases and a number of others operated on after 1884. This paper, which is in two parts, contains an evaluation of the claims made for the priority of Macewen's pre-1884 operations. Part I deals mainly with Macewen's work in fields other than brain surgery that are relevant to it and sets out the facts of the controversy. It begins with a brief biography of Macewen, describes his pioneering work in antiseptic and aseptic surgery, his work on osteotomy and bone regeneration, and his use in brain surgery of the knowledge so gained. Part I concludes with an examination of the battle waged in the newspapers between Macewen's and Bennett's and Godlee's supporters, and of previously unpublished correspondence between Macewen himself, David Ferrier and Hughes Bennett. The primary records of the patients on whom Macewen operated, together with other materials relevant to the controversy, are examined in Part II.