Biomedical subjects

Garnette R Sutherland

Publications and source records attributed to Garnette R Sutherland.

6 recordsLinked to original sources

PubMed2003

Chronic endothelin antagonism restores cerebrovascular function in diabetes.

OBJECTIVE: Diabetes profoundly alters vascular function and is a risk factor for cerebrovascular disease. Diabetes increases myogenic tone and decreases responsiveness to adenosine triphosphatase (ATP)-sensitive K(+) (K(ATP)) channel openers and endothelium-dependent vasodilators. The mechanism(s) by which diabetes impairs cerebrovascular function remain obscure. In the present study, the effects of the potent vasoactive peptide endothelin-1 on myogenic tone and endothelium-dependent and potassium channel-mediated vasodilation in middle cerebral arteries from diabetic and nondiabetic rats were investigated. METHODS: Twenty-eight Wistar rats were divided into four experimental groups (n = 7 per group): control (C), control treated with bosentan (an endothelin A/B receptor antagonist) (CB), diabetic (D), and diabetic bosentan-treated (DB). Diabetes was induced with streptozotocin (D and DB groups), after which chronic bosentan treatment was initiated (CB and DB groups). Middle cerebral arteries were mounted in a pressure myograph, and myogenic responses were recorded. In addition, endothelium-dependent and -independent responses and the effects of the K(ATP) channel opener pinacidil were examined. RESULTS: Cerebral arteries from the diabetic and nondiabetic rats constricted in response to graded pressure increases. Maximum myogenic responses (percent constriction at 60 mm Hg) were significantly greater in the D group (38 +/- 3% versus 25 +/- 3% in C; P < 0.02). The enhanced myogenic tone in the D group was completely prevented by bosentan treatment (DB, 23 +/- 5% versus D; P < 0.003) without an effect on the CB group. In addition, bosentan treatment improved endothelium-dependent vasomotion and improved K(ATP)-mediated vasodilation in the DB group (P < 0.001). CONCLUSION: These data describe, for the first time, the interaction between endothelin-1, myogenic tone, and endothelial function in diabetes. Chronic endothelin antagonism restores cerebrovascular function in this model of diabetes and has global implications for the management of cerebrovascular disease in diabetes.

Animals↗

PubMed2003

From microscopic to astronomic, the legacy of Carl Zeiss.

IN 1846, CARL ZEISS established a workshop to make lenses for microscopes, cameras, binoculars, and astronomical observatories. He was a master craftsman and was intolerant of any flaw, destroying microscopes with only minor inaccuracies. His relentless pursuit of perfection brought him into contact with a brilliant physicist, Ernst Abbe. Zeiss combined Abbe's new optical laws with his own technical skills; together, they created a colossus. Their company came to be known not only for exquisite technical standards but also for labor relations that were and remain progressive. The development of microneurosurgery was aided by the active participation of Carl Zeiss, Inc. The history of this company provides a lesson in the power of entrepreneurship and the benefits to humanity that can accrue from a fruitful partnership between medical science and industry.

Astronomy↗

PubMed2003

Aneurysm clips.

This communication outlines the development of aneurysm clips, from those originally used by Walter Dandy to those in use today. The history is rich, with many contributions from neurosurgical pioneers and innovators. As a result, the modern neurosurgeon has a wide selection of biocompatible aneurysm clips from which to choose, clips that have known closing pressures and various sizes and shapes, as well as a selection of clip applicators that do not obstruct the surgical field.

Aneurysm↗

PubMed2002

Intraoperative mobile magnetic resonance imaging for craniotomy lengthens the procedure but does not increase morbidity.

PURPOSE: To evaluate anesthetic aspects of care provided for craniotomy using mobile intraoperative magnetic resonance imaging (iMRI). METHODS: Anesthetic factors were studied using a retrospective case-control design. The primary outcome measures were the duration of the surgical intervention; the recovery score and body temperature on arrival; and length of stay in the post-anesthetic care unit. Secondary outcome measures were estimated blood loss, perioperative transfusion requirements, and fluids administered. RESULTS: Seventy-six patients undergoing craniotomy in the MRI theatre were compared with a case-matched control group of patients who underwent neurosurgical interventions in the conventional operating room during the same time period. The only outcome measure that differed between the two groups of patients was the duration of surgery: the mean duration of procedures for patients who underwent imaging was 407 +/- 143 min compared to 285 +/- 122 min in the conventional operating theatre (P < 0.000). Actual time spent imaging accounted for approximately 100 min (83%) of the increased duration. CONCLUSION: Our results do not support concerns that the iMRI suite is a "hostile" environment for the delivery of anesthesia for craniotomy. With the exception of an increased duration of the procedure, patients undergoing anesthesia with iMRI showed no differences from those operated in the conventional operating theatres.

Adult↗

PubMed2002

Optimizing epilepsy surgery with intraoperative MR imaging.

PURPOSE: The surgical treatment of medically intractable temporal lobe epilepsy includes the resection of temporal lobe structures. Although the reported seizure-free outcomes are highly variable, there is growing evidence that the extent of resection of the mesiotemporal lobe directly correlates with seizure control. METHODS: A moveable, high-field intraoperative magnetic resonance (MR) system was used to monitor and optimize the resection of the amygdala and hippocampus in 14 epilepsy patients. Fourteen patients with intractable seizures of temporal lobe origin underwent standard preoperative investigations including MR imaging, EEG telemetry, single-photon emission computed tomography, and neuropsychologic and sodium amytal testing. Anterior temporal lobectomy was performed on 10 patients, whereas four were treated with selective amygdalohippocampectomy. Intraoperative electrocorticography was applied as required. For all procedures, the objective was to resect the amygdala completely, and hippocampus to the posterior margin of the brainstem. RESULTS: Interdissection intraoperative MR imaging taken when optimal resection was thought to have been achieved revealed residual unresected amygdala or hippocampus in seven of 14 patients. An unexpected acute hematoma was found in one patient. At 17 months' follow-up, 13 (93%) of 14 patients are seizure free or have significantly improved seizure control. CONCLUSIONS: The mobile high-field intraoperative MR system provides high-resolution images without restriction on surgical instruments or techniques. The ability to identify and resect residual mesial temporal lobe targets before craniotomy closure is of potentially tremendous value in optimizing seizure control.

Adult↗

PubMed2002

Intraoperative assessment of aneurysm clipping using magnetic resonance angiography and diffusion-weighted imaging: technical case report.

OBJECTIVE AND IMPORTANCE: To use intraoperative magnetic resonance imaging, including magnetic resonance angiography and diffusion-weighted imaging, to monitor the surgical treatment of a patient with an intracranial aneurysm. TECHNIQUE: Intraoperative imaging was performed with a ceiling-mounted, mobile, 1.5-T magnet (developed in collaboration with Innovative Magnetic Resonance Imaging Systems, Inc., Winnipeg, MB, Canada) that included high-performance 20-mT/m gradients. Pre- and postclipping, intraoperative, T1-weighted, angiographic and diffusion-weighted magnetic resonance images were obtained from a patient with an incidental, 8-mm, anterior communicating artery aneurysm. RESULTS: T1-weighted images demonstrated brain anatomic features, with visible shifts induced by surgery. Magnetic resonance angiography demonstrated the aneurysm and indicated that, after clipping, the A1 and A2 anterior cerebral artery branches were patent. Diffusion-weighted studies demonstrated no evidence of brain ischemia. CONCLUSION: For the first time, intraoperative magnetic resonance imaging has been used to monitor the surgical treatment of a patient with an intracranial aneurysm.

Humans↗