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Michael O'Brien

Publications and source records attributed to Michael O'Brien.

26 records · Page 2Linked to original sources
PubMed2004

Hereditary haemochromatosis is unlikely to cause movement disorders--a critical review.

Hereditary haemochromatosis (HH) is a common autosomal recessive systemic iron overload disorder in which CNS manifestations, particularly movement disorders, have been reported. We report a 63-year-old woman with familial HH with a four-year history of progressive gait disturbance, chorea, and mild cervical and laryngeal dystonia. Her movement disorder was thought to be related to the haemochromatosis. On further investigation, analysis for the Huntington's disease expansion was positive. A review of the seven published cases of movement disorders associated with HH as well as data concerning brain iron deposition in this condition leads us to debate the causal link between movement disorders and HH. We suggest that movement disorders are rare in association with HH, and that such patients should be thoroughly investigated for another cause for their movement disorder.

Basal Ganglia↗
PubMed2004

Intensity and direction of competitive anxiety as a function of sport type and experience.

Using Jones' (1995) model of control, intensity (level) and direction (interpretation) of symptoms associated with competitive trait anxiety were examined as a function of sport type and competitive experience. Participants from gross explosive and fine motor-skill sports (n = 162) completed a trait version of the Competitive State Anxiety Inventory-2 (Martens et al., 1990a) including intensity and direction subscales (Jones & Swain, 1992). Main effects for experience and sport type were reported with gross explosive sports indicating symptoms associated with competitive anxiety as more facilitative to performance than fine motor-skill sports. Experienced performers also reported more-facilitating interpretations of symptoms than their less-experienced counterparts. The findings provide support from a dispositional context to suggest that sport type and the level of competitive experience influence interpretation of symptoms usually experienced in pressure situations. Implementation of activation, relaxation or restructuring interventions contingent upon the nature of the sport is recommended with consideration of the development of confidence-building strategies in less-experienced performers.

Adult↗
PubMed2004

Rifalazil treats and prevents relapse of clostridium difficile-associated diarrhea in hamsters.

Although vancomycin and metronidazole effectively treat Clostridium difficile-associated diarrhea and colitis (CDAD), their use is associated with a high incidence of relapsing C. difficile infection. Rifalazil is a new benzoxazinorifamycin that possesses activity against Mycobacterium tuberculosis and gram-positive bacteria. Here we compared rifalazil and vancomycin for effectiveness in preventing or treating clindamycin-induced cecitis in a hamster model of CDAD. Golden Syrian hamsters were injected subcutaneously with clindamycin phosphate (10 mg/kg), followed 24 h later by C. difficile gavage. Hamsters received by gavage for 5 days vehicle, vancomycin (50 mg/kg), or rifalazil (20 mg/kg) either simultaneously with (prophylactic protocol) or 24 h after C. difficile administration (treatment protocol). While all vehicle-administered animals became moribund within 48 h of C. difficile administration, no rifalazil- or vancomycin-treated animals in either protocol showed signs of morbidity after 7 days. Ceca of rifalazil-treated animals showed absence of epithelial cell damage, significantly reduced congestion and edema, and less, but not statistically significantly less, neutrophil infiltration compared to those of vehicle-treated animals. In contrast, vancomycin-treated animals demonstrated severe epithelial cell damage and mildly reduced congestion and edema. Moreover, hamsters relapsed and tested C. difficile toxin positive (by enzyme-linked immunosorbent assay) 10 to 15 days after discontinuation of vancomycin treatment. None of the rifalazil-treated hamsters showed signs of disease or presence of toxins in their feces 30 days after discontinuation of treatment. Our results indicate that once daily rifalazil may be superior to vancomycin for curative treatment of CDAD.

Animals↗
PubMed2003

Colonic metaplasia in the ileal pouch is associated with inflammation and is not the result of long-term adaptation.

Ileal pouch-anal anastomosis (IPAA) is the preferred surgical therapy for chronic ulcerative colitis (CUC) and familial adenomatous polyposis (FAP). Previous studies have demonstrated morphologic changes in pouch mucosa such as villous atrophy and crypt hyperplasia. These changes have been labeled "colonic metaplasia." The aims of this study were to determine whether these changes represent "normal" long-term adaptation of the nondiseased pouch or instead are present only in the setting of inflammation. Twenty-four patients were identified, greater than 5 years status post-IPAA for CUC, who underwent pouchoscopy for surveillance and had no history of pouchitis. Thirty-one patients were identified greater than 5 years status post-IPAA for CUC, who had a history of pouchitis and had undergone pouchoscopy at least 5 years status post-IPAA. Eight patients status post-IPAA for FAP were also identified. Biopsy specimens were reevaluated by a single, blinded pathologist for degree of inflammation, the presence of villous atrophy and crypt hyperplasia, and evidence of dysplasia. Among the patients with CUC, the inflammation score was greater in the pouchitis group, 13.2 +/- 1.2, compared to the nonpouchitis group, 4.0 +/- 0.5 (P < 0.0001). Median colonic metaplasia score was greater in the pouchitis group (4 [range 2 to 6]) vs. 2 (9 [range 0 to 6]; P < 0.0001). The colonic metaplasia score correlated with the inflammation score (Spearman coefficient r = 0.83; P < 0.0001). In the eight patients with FAP, the inflammation score was 5.1 +/- 0.9 and the median colonic metaplasia score was 1 (range 0 to 4). There was no evidence of dysplasia in any of the biopsy specimens. Patients without a history of pouchitis or symptoms of pouchitis have only a minimal degree of villous atrophy and crypt hyperplasia. These morphologic changes in the ileal pouch are found primarily in the setting of inflammation, and likely represent a reparative response.

Adaptation, Physiological↗
PubMed2002

Platelet calmodulin levels in adolescent idiopathic scoliosis: do the levels correlate with curve progression and severity?

STUDY DESIGN: This ongoing longitudinal study evaluates simultaneous radiographic and platelet calmodulin determinations for patients with idiopathic scoliosis who are skeletally immature. OBJECTIVES: To determine whether platelet calmodulin levels correlate with curve progression and severity. SUMMARY OF BACKGROUND DATA: A previous study based on a single calmodulin determination and a single radiograph identified higher calmodulin levels in progressive curves and in higher magnitude curves. A longitudinal study was needed to demonstrate the relation of calmodulin to curve changes for individual patients over time during the growth period. METHODS: In this study, 55 patients with idiopathic scoliosis of varying types and severity were followed longitudinally with serial radiographs and platelet calmodulin determinations. A Risser sign was recorded for each radiograph at each visit. RESULTS: Calmodulin levels increased in all the patients with progressive curves (13/13), remained stable in 73% of the patients with nonprogressive curves (11/15), and were higher generally in curves greater than 30 degrees and double structural curves. Calmodulin levels usually decreased in patients undergoing brace treatment (14/17) or spine fusion (9/10). CONCLUSIONS: It appears that platelet calmodulin levels correlate closely with curve progression and stabilization by bracing or spine fusion. Correlation with nonprogressive curves was not as consistent, with 27% noncorrelation. Longer follow-up evaluation and enrollment of additional patients will be necessary to determine whether calmodulin may serve as a biochemical marker of curve progression and to help identify stable and progressive curves.

Adolescent↗
PubMed2002

Central and juxta-endplate vertebral body screw placement: a biomechanical analysis in a human cadaveric model.

STUDY DESIGN: In vitro biomechanical testing of transvertebral body screws in different positions in both axial pull-out and toggle. OBJECTIVES: To determine the relative strength of unicortical versus bicortical screw fixation within the vertebral body and to determine comparative strength of juxta-endplate and central screw positions with and without staples in both axial pull-out and toggle modes. SUMMARY OF BACKGROUND DATA: Loss of fixation is common in centrally placed screws at the rostral end of a construct. To preserve segmental vessels, juxta-endplate screw positions are often used. The biomechanical strength of such screw placement methods has not been measured. METHODS: Eighty-three human cadaveric vertebral bodies were tested for axial pull-out and toggle with and without staples. Screw positions included central, juxta superior, and inferior endplate. Juxta-endplate screws were toggled in both the rostral and caudal directions perpendicular to the screw axes. RESULTS: Unicortical fixation resulted in a 93% decrease in axial pull-out strength compared with bicortical fixation. Centrally placed screws and juxta-endplate screws were equivalent in axial pull-out if no staples were used. The juxta-endplate screw with a staple that was toggled away from the endplate had the highest yield strength, followed by the central screw with a staple, and then the juxta-endplate screw without a staple toggled away from the endplate. CONCLUSIONS: Bicortical fixation is much stronger than unicortical fixation. Centrally placed screws are significantly stronger when used with a staple. When preservation of segmental vessels is desirable, juxta-endplate screws should be placed in such a manner that compressive forces are directed away from the endplate.

Adolescent↗