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Biomedical subjects

Peter Petersen

Publications and source records attributed to Peter Petersen.

5 recordsLinked to original sources
PubMed2005

Centralization: its prognostic value in patients with referred symptoms and sciatica.

STUDY DESIGN: Prospective, comparative cohort study. OBJECTIVE: To investigate the prognostic significance of centralization in patients with subacute sciatica and referred symptoms. SUMMARY OF BACKGROUND DATA: Previous studies have shown that centralization occurs commonly in the nonspecific low back population, and its occurrence is associated with a good prognosis. The phenomenon has never been evaluated in a population with sciatica and referred symptoms. METHODS: The sample pool was 104 consecutive patients referred for investigation of possible disc herniation. Of these patients, 60 were recruited into the study and underwent a standardized mechanical evaluation using repeated end-range movements, while symptom response was monitored to expose 2 groups: centralization group (CG) and noncentralization group (NCG). All patients were treated in the same way and were followed for one year. If patients did not have improvement surgery was considered. Outcomes included back and leg pain, disability, Nottingham Health Profile, and surgical outcome. RESULTS: There were 25 patients who were classified in the CG, 35 in the NCG, and other baseline characteristics were similar between groups. At 1, 2, and 3 months, the CG had significantly better outcomes than the NCG. At 2 months, the CG had more improvements in leg pain (P = 0.007), disability (P = <0.001), and Nottingham Health Profile (P = 0.001). After 1 year, disability was less in the CG (P = 0.029). In the CG, 3 patients underwent surgery, in the NCG, 16 (P = 0.01). The odds ratio for surgery in the NCG was 6.2. CONCLUSION: Patients with sciatica and suspected disc herniation who have a centralization response to a mechanical evaluation will have significantly better outcomes. Patients who do not have centralization will be 6 times more likely to undergo surgery.

Adolescent↗
PubMed2005

A novel MATE family efflux pump contributes to the reduced susceptibility of laboratory-derived Staphylococcus aureus mutants to tigecycline.

Tigecycline, an expanded-broad-spectrum glycylcycline antibiotic is not affected by the classical tetracycline resistance determinants found in Staphylococcus aureus. The in vitro selection of mutants with reduced susceptibility to tigecycline was evaluated for two methicillin-resistant S. aureus strains by serial passage in increasing concentrations of tigecycline. Both strains showed a stepwise elevation in tigecycline MIC over a period of 16 days, resulting in an increase in tigecycline MIC of 16- and 32-fold for N315 and Mu3, respectively. Transcriptional profiling revealed that both mutants exhibited over 100-fold increased expression of a gene cluster, mepRAB (multidrug export protein), encoding a MarR-like transcriptional regulator (mepR), a novel MATE family efflux pump (mepA), and a hypothetical protein of unknown function (mepB). Sequencing of the mepR gene in the mutant strains identified changes that presumably inactivated the MepR protein, which suggested that MepR functions as a repressor of mepA. Overexpression of mepA in a wild-type background caused a decrease in susceptibility to tigecycline and other substrates for MATE-type efflux pumps, although it was not sufficient to confer high-level resistance to tigecycline. Complementation of the mepR defect by overexpressing a wild-type mepR gene reduced mepA transcription and lowered the tigecycline MIC in the mutants. Transcription of tet(M) also increased by over 40-fold in the Mu3 mutant. This was attributed to a deletion in the promoter region of the gene that removed a stem-loop responsible for transcriptional attenuation. However, overexpression of the tet(M) transcript in a tigecycline-susceptible strain was not enough to significantly increase the MIC of tigecycline. These results suggest that the overexpression of mepA but not tet(M) may contribute to decreased susceptibility of tigecycline in S. aureus.

Anti-Bacterial Agents↗