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Biomedical subjects

Mark Richardson

Publications and source records attributed to Mark Richardson.

6 recordsLinked to original sources
PubMed2006

Tracheal reconstruction with porcine small intestine submucosa in a rabbit model.

OBJECTIVE: To evaluate the ability of porcine small intestine submucosa (SIS) to 1) maintain airway patency, 2) integrate, 3) prevent granulation tissue formation, and 4) permit mucosalization when used for tracheal reconstruction. Further studies were performed to evaluate the ability of SIS to support neochondrogenesis and investigate the impact of neochondrogenesis on airway patency. STUDY DESIGN: Prospective, controlled animal trial with SIS used with and without a perichondrial flap to reconstruct a tracheal defect in a rabbit model. Functional, histologic and endoscopic analyses were performed. RESULTS: All animals except 1 control animal were without stridor. The SIS graft supported neochondrogenesis, was completely mucosalized and was well integrated into the neotrachea. There was minimal granulation tissue formation. Endoscopic analyses did not reveal a consistent, significant difference in airway patency when SIS, with or without a perichondrial flap, was used for reconstruction. CONCLUSION: SIS can be used to reconstruct a sublethal rabbit tracheal defect with no mortality and minimal morbidity.

Airway Obstruction↗
PubMed2006

Excess post-exercise oxygen consumption in untrained males: effects of intermittent durations of arm ergometry.

The purpose of this study was to investigate excess post-exercise oxygen consumption (EPOC) following a continuous 30 min bout of upper-body exercise (UBE) compared with 3 consecutive 10 min bouts of UBE. Ten male subjects (age (mean +/- standard deviation), 25.7 +/- 5.83 years; arm VO(2) (peak), 2.2 +/- 0.25 L x min(-1), on separate days (48 h between trials) and in counterbalanced order, performed a continuous 30 min bout of arm exercise at 60% of arm VO2 peak and 3 separate 10 min bouts of arm exercise at 60% of arm VO(2) (peak). Subjects reported to the laboratory rested and after a 12 h fast. Each test was preceded by a 30 min baseline test to determine resting metabolic rate. Post-exercise VO2 was continuously monitored until baseline was re-established. Results showed that the combined magnitude of the EPOCs from the intermittent exercise sessions was significantly (p > .05) greater (4.47 +/- 1.58 L O2) than that elicited from the continuous exercise session (1.54 +/- 1.25 L O2). These data indicate that separating a continuous 30 min arm exercise into 3 equal 10 min arm exercises will elicit a small but significantly higher EPOC, and thus result in greater post-exercise energy expenditure. This could be beneficial for those unable to perform lower-body exercise (LBE), or for those with limited exercise capacities.

Adolescent↗
PubMed2004

Small bowel tumours: a 10 year experience in four Sydney teaching hospitals.

BACKGROUND: Small bowel tumours are uncommon and can have a long delay prior to diagnosis. The present study aims to compare the use of computed tomography (CT) and contrast small bowel series (SBS) in their diagnosis and to outline the clinical features of small bowel tumours. METHODS: A retrospective, case note study was conducted between 1990 and 2000 in four Sydney teaching hospitals. The data collected included clinical features, investigations and tumour characteristics. RESULTS: One hundred and sixty-six people with small bowel tumours were identified (91 malignant; 75 benign). Malignant tumours consisted of adenocarcinomas (31%), carcinoid tumours (12%), lymphomas (7%) and leiomyosarcomas (5%). Benign tumours consisted of adenomas (22%), hamartomas (13%), leiomyomas (4%), inflammatory polyps (4%) and hyperplastic polyps (2%) and a benign schwannoma (1%). Adenocarcinomas were mainly located in the duodenum (P < 0.001) and carcinoid tumours in the ileum (P < 0.001). Malignant tumours were associated with a higher proportion of symptoms (P < 0.01), signs (P < 0.001) and episodes of small bowel obstruction (P < 0.01). Abdominal CT scans demonstrated a greater sensitivity (87.7%) than SBS (72.9%) with a slightly improved sensitivity when both investigations were used (89.3%). Abdominal ultrasound had a lower sensitivity than both of the above investigations of 65%. Gastroduodenoscopy had a sensitivity of 90% for diagnosing duodenal tumours. Operative procedures were performed on 92 patients with a preoperative diagnosis made in 77%. Metastatic spread of malignant tumours was evident in 46%. The sites of spread were to lymph nodes (23%), liver (21%) and distant locations (2%) at diagnosis. CONCLUSIONS: Malignant small bowel tumours are more likely to produce symptoms and signs than benign tumours, particularly caused by small bowel obstruction. Abdominal CT is the best radiological investigation for small bowel tumours and has a slight complimentary effect with SBS in improving the chances of detection. Gastroduodenoscopy remains the best investigation of duodenal tumours.

Adolescent↗
PubMed2003

Identification of the optimal intercondylar starting point for retrograde femoral nailing: an anatomic study.

BACKGROUND: Retrograde nailing of femoral shaft fractures is an effective and increasingly more popular method of fracture fixation. However, concern remains regarding the effect of the intercondylar entry-portal location on knee function. METHODS: The optimal entry-portal location was identified in cadaver femurs. Approximating the clinical intraoperative situation, a threaded guidewire was inserted into each of 26 distal femur specimens and positioned in the center of the femoral shaft as determined by anteroposterior and lateral fluoroscopic imaging. Each guidewire was then overdrilled with a 12-mm cannulated drill bit. All entry-portal locations were recorded relative to the posterior cruciate ligament attachment and the intercondylar groove and mapped relative to the known patellofemoral contact area. RESULTS: The starting holes averaged 6.21 mm anterior to the posterior cruciate ligament attachment and 2.67 mm medial to the intercondylar groove. Overall, 100% of starting portals were located in safe areas relative to the patellofemoral contact area. CONCLUSION: In the vast majority of femurs, the optimal entry portal for retrograde femoral nailing (in line with the long axis of the femur) is located in the expected safe position, anterior to the posterior cruciate ligament insertion and slightly medial to center of the intercondylar groove. However, because of anatomic variability, the ideal starting position occasionally may be located in a patellofemoral contact area. Potential compromise of the patellofemoral contact area by the retrograde nail entry portal can and should be recognized before nailing, allowing the surgeon the option of altering the surgical technique.

Bone Nails↗
PubMed2003

A series of studies--a practical protocol for testing muscular endurance recovery.

The purpose of this series of studies was to use a practical measure to examine the course of muscular endurance recovery after 3 sets to failure in 10 men (ages 18 to 30 years) and then compare those results with 10 men (ages 18 to 30 years) who performed 7 sets and 10 older men (ages 50 to 65 years) who performed 3 sets. Recovery as indicated by number of repetitions performed was observed at 24, 48, 72, and 96 hours. Repeated-measures ANOVA was used to investigate differences in recovery over time. For group means, performance was significantly lower in all 3 groups after 24 hours (p < 0.05). At 48 hours, performance of the groups was not significantly different from baseline (p > 0.05). Number of repetitions performed at 72 hours was significantly higher than that in session 1 (10.2 +/- 1.4 reps in session 1 vs. 11.2 +/- 2.3 at 72 hours, p = 0.022) in the young 3-sets group, but not in the other groups. After 96 hours, only the young 7-sets group was found to be performing at a level approaching significance (10.3 +/- 1.2 reps in session 1 vs. 11.1 +/- 2.0 at 96 hours, p = 0.051). No significant difference was found between the young 3-sets and 7-sets groups at any time (p > 0.05). The young 3-sets group was found to be performing at a significantly higher level than the older group at 72 hours (11.2 +/- 2.3 reps in the younger vs. 9.9 +/- 1.7 in the older group, p = 0.008), a difference that also approached significance at 96 hours (p = 0.06). Large intersubject variability was observed at all time points. The results suggest that individual recovery testing before exercise prescription is practical, and this protocol may be sensitive to differences in training volume and subject age.

Adolescent↗