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David G Walker

Publications and source records attributed to David G Walker.

9 recordsLinked to original sources
PubMed2006

T-cell apoptosis in human glioblastoma multiforme: implications for immunotherapy.

We used immunohistochemistry and flow cytometry to assess apoptosis in human glioblastoma multiforme (GBM). Our immunohistochemical study revealed apoptosis of glioma cells expressing glial fibrillary acidic protein and of CD3(+) T cells infiltrating GBM. To quantify and phenotype the apoptotic T cells, we performed flow cytometry on lymphocytes separated from GBM. The cells were stained with annexin-V-FLUOS/propidium iodide to identify apoptosis. We found that high proportions of both the CD4(+) and CD8(+) T cells were apoptotic. In particular, we found that T cells expressing Fas ligand (Fas-L, CD95L) were eight times more vulnerable to apoptosis than those not expressing Fas-L, which suggests that the T-cell apoptosis is induced by overactivation of the T-cell receptor, possibly in the absence of appropriate costimulation. Our results have implications for the design of immunotherapies for GBM.

Apoptosis↗
PubMed2004

More than one dilemma.

We present an unusual case that highlights a number of management dilemmas: the cause, investigation and treatment of subarachnoid hemmorrhage in patients iwth vascular connective tissue diseases; the further investigation of small aneurysms identified on CT angiography; and the difficulties associated with anticoagulation, mechanical cardiac valves and cerebral hemorrhage.

Adult↗
PubMed2002

Intraoperative magnetic resonance: the future of surgery.

Intraoperative magnetic resonance imaging (iMRI) is a new development in medicine that bridges the specialties of surgery and radiology. Deficiencies in the visualization of anatomical architecture and the perception of tumour boundaries in conventional open surgery have led to the integration of imaging within surgery. The superior soft tissue and multiplanar imaging features of magnetic resonance (MR) make this imaging modality superior to that of alternatives. The unique properties of MR to detect heat change and perfusion, and diffusion characteristics of tissue enhance the usefulness of this medium. Concurrent developments in computer aided image guidance and thermoablative technology, herald the era of minimally invasive tumour ablation. Applications have been developed for areas such as neurosurgery, general surgery, gynaecology and urology.

Australia↗
PubMed2002

Frameless stereotaxy as an alternative to fluoroscopy for transsphenoidal surgery: use of the InstaTrak-3000 and a novel headset.

Our aim was to evaluate the applicability of an electromagnetic-based frameless stereotactic system for use in transsphenoidal surgery. The system utilizes a novel headset that acts as a replaceable fiducial frame as well as a fixation point for the system's transmitter. It can replace the fluoroscope as a guide to navigation in the sphenoid sinus and sella. The system was used in a consecutive series of 11 patients undergoing transsphenoidal surgery. It was used in conjunction with intraoperative fluoroscopy. We found the Instatrak-3000 to correlate well with lateral fluoroscopic images, and provide additional information in the axial and coronal planes. The InstaTrak-3000 frameless stereotactic system is accurate and obviates the need for intraoperative fluoroscopy during transsphenoidal surgery. Compared to other frameless systems, it avoids the use of fiducial skin markers and head fixation. In common with other frameless stereotactic systems, it provides additional information important for safely approaching the sella and avoids intraoperative radiation exposure for the patient and operating room staff.

Adenoma↗
PubMed2002

Intraoperative magnetic resonance for the surgical treatment of lesions producing seizures.

Seizures are a major presenting feature of several non-neoplastic cerebral lesions. We reviewed the experience at the Brigham and Women's Hospital, Boston, on the surgical management of benign intracerebral lesions presenting with seizures with intraoperative magnetic resonance imaging (iMRI) guidance. Our aim was to demonstrate that this is an effective and efficient treatment for these lesions. The histories of thirteen patients who presented with seizures secondary to benign intraaxial lesions treated by craniotomy and resection within the iMRI unit at our institution were reviewed. The surgical results, histology and clinical outcomes were reviewed. The mean follow-up was 22.1 months (range 2-48). In all cases, lesions were accurately located with iMRI. After initial macroscopic resection, 5 cases were found to have residual lesion. All had complete radiological resection at the end of the procedure. At follow-up, five patients had no seizures, 5 had rare seizures and the remaining 3 had worthwhile improvement in seizure frequency. Intraoperative MRI is a safe and effective adjunct for the surgical treatment of benign intracerebral lesions presenting with seizures. It provides effective and efficient intraoperative guidance for planning and approach to the lesion and the assurance that the lesion is totally removed. Surgical resection with iMRI may, therefore, provide a useful approach to these lesions.

Adolescent↗
PubMedDate not supplied

The role of cranial expansion for craniocephalic disproportion.

The appropriate treatment for craniocephalic disproportion, such as caused by slit ventricle syndrome, is uncertain. We have reviewed the treatment and outcomes of 4 children who underwent cranial expansion over a period of 5 years. The ages at cranial expansion were 16 months, 3 years 6 months and 2 at 6 years. Two children had slit ventricle syndrome and were treated with bilateral parietal expansions. Two children had non-syndromic craniosynostosis, one of these having vitamin D-resistant rickets. The latter 2 were treated with posterior cranial vault expansion, and one also had a craniocervical junction decompression performed. Post-operatively, symptoms of raised intracranial pressure resolved in all cases, and there was radiological evidence of re-establishment of normal CSF pathways. Although a rare condition, cranial expansion operations can be successful in appropriately selected cases of craniocephalic disproportion.

Cephalometry↗