Biomedical subjects

B Greenhill

Publications and source records attributed to B Greenhill.

3 recordsLinked to original sources

PubMed2001

The critical stage of pinealectomy surgery after which scoliosis is produced in young chickens.

STUDY DESIGN: Stages of the surgical procedure for pinealectomy in chickens were identified. Groups of chickens were selected for each stage. Scoliosis development was identified from radiographs. OBJECTIVES: To determine the critical stage of surgery for pinealectomy after which scoliosis develops in young chickens. SUMMARY OF BACKGROUND DATA: Pinealectomy in young chickens consistently produces scoliosis in young chickens that has many characteristics similar to those seen in patients with adolescent idiopathic scoliosis. The mechanism behind this phenomenon remains unknown. METHODS: Five distinct stages in the pinealectomy surgery were identified. Groups of chickens were selected to undergo surgery to represent these five stages. Scoliosis was determined from weekly radiographs. RESULTS: Cutting the pineal stalk was identified as the critical stage in the surgery after which scoliosis developed. The incidence of scoliosis did not increase after more extensive surgery in which the pineal bulb was removed from the skull. This stage was also correlated with a significant reduction of serum melatonin levels. CONCLUSIONS: Cutting the pineal stalk was identified as the critical stage of pinealectomy surgery after which scoliosis may develop. This stage was also correlated with the significant reduction of average serum melatonin levels. These results allow the focus of attention into the mechanism behind this phenomenon to center on the consequences of cutting the pineal stalk rather than total removal of the pineal gland.

Animals↗

PubMed1995

A transpedicularly implanted anterior spinal support.

This article describes a device that has been developed to augment posterior spinal fracture fixation by providing support for the anterior column of the spine. The device is contracted for insertion through the limited opening provided by the transpedicular approach to the vertebral body. Once in situ it is configured to support physiological loads. In this way the structural limitations of posterior instrumentation and the surgical difficulties of anterior spinal fixation instrumentation are overcome. A preliminary investigation of the new device together with in vitro studies of a prototype are described in this report. In vitro tests to determine the expansion characteristics and structural performance of the device were performed together with tests to determine the efficacy of the support to reduce loading on the posterior fixation device. It is shown that the device has the necessary expansion characteristics and can support physiological loads without failure. Tests using porcine vertebral columns with a simulated vertebral fracture showed a significant reduction in load carried by the posterior fixation plates (44 +/- 16%) when the anterior support was included in the construct. In addition, the difference in loading between the left and right plates was significantly reduced (81 +/- 12%).

Bone Cements↗

PubMed1983

Analysis of vertebral muscle obtained during surgery for correction of a lumbar disc disorder.

Biopsies of erector spinae (sacrospinalis) and multifidus muscles were taken, in a precise manner, adjacent to lumbar vertebra 5, from 18 patients aged 28-73, suffering from acute lumbar disc disorders. The respective muscle fiber characteristics were assessed histologically and histochemically using ATPase and NADH staining procedures. A 'strength factor' component was developed for each muscle by combining measurements of fiber area and fiber type, to introduce a functional indication of force. No obvious signs of muscle pathology were evident histologically or histochemically. While a large difference in muscle characteristics may exist on opposite sides of the vertebral column in individual subjects, these differences do not appear to be related to the side of the disc protrusion. It is therefore suggested that muscle obtained from patients suffering from disc protrusion can be used as representative of normal muscle.

Adult↗