Markus Haas | PubMed Health

PubMed2004

Evaluation of pulpal blood flow after tooth splinting of luxated permanent maxillary incisors.

Laser Doppler flowmetry (LDF) is a non-invasive method to assess pulpal blood flow (PBF). Dental injury has been associated with losses of pulpal sensibility. The purpose of this study was to assess whether LDF could be used to detect short- and long-term changes of PBF values of luxated permanent maxillary central incisors after repositioning and splinting. In 18 trauma patients, a single maxillary incisor treated by repositioning and splinting, and the respective contralateral homologous tooth were investigated by LDF to assess local PBF values. Perfusion units (PU) were taken in four sessions: on the day of splint removal, and 12, 24, and 36 weeks after splint removal. Analysis of the luxation type-related PBF measurements revealed intrusion type-related PBF values to be associated with a significant decrease in PBF values (P < 0.05), while lateral luxation and extrusion type-related PBF values showed no significant difference between the session-related values (P > 0.05). PBF measurements did not change over time for the contralateral incisors (P > 0.05). Teeth affected by an intrusion-type luxation injury remained unresponsive to sensitivity testing at follow up, while 3 (60%) developed grey discoloration of the crown. LDF may become useful in the detection of ischemic episodes of luxated maxillary central incisors after repositioning and splinting. Further studies are warranted to assess the validity of post-traumatic 'ischemic episodes' by comparing it to histological tooth pulp changes.

Adolescent↗

PubMed2002

Escherichia coli insertion sequence IS150: transposition via circular and linear intermediates.

IS150, a member of the widespread IS3 family, contains two consecutive out-of-phase open reading frames, orfA and orfB, that partially overlap. These open reading frames encode three proteins, InsA, InsB, and the InsAB protein, which is jointly encoded by both open reading frames by means of programmed translational frameshifting. We demonstrate that the InsAB protein represents the IS150 element's transposase. In vivo, the wild-type IS150 element generates circular excision products and linear IS150 molecules. Circular and linear species have previously been detected with mutant derivatives of other members of the IS3 family. Our finding supports the assumption that these products represent true transposition intermediates of members of this family. Analysis of the molecular nature of these two species suggested that the circular forms are precursors of the linear molecules. Elimination of InsA synthesis within the otherwise intact element led to accumulation of large amounts of the linear species, indicating that the primary role of InsA may be to prevent abortive production of the linear species and to couple generation of these species to productive insertion events.

DNA Transposable Elements↗