Analogue Special and General Relativity by Optical Multilayer Thin Films: The Rindler Space Case

In this paper, to obtain an analogy between the curved spaces and the linear optics, we expand the idea of Ref.[1, 2] to the multilayer films. We investigate efects of thickness and index of refraction of the films on the Lorentzian transformations. In addition, by using the multilayer films, we suggest very simple experimental set-up which can serve as an analogue computer for testing special relativity. Finally, we draw an analogy between the Rindler space, as an example of the curved spaces, and a suitable multilayer film.Comment: 5 Figure

Notch receptor expression in human brain arteriovenous malformations

The roles of the Notch pathway proteins in normal adult vascular physiology and the pathogenesis of brain arteriovenous malformations are not well-understood. Notch 1 and 4 have been detected in human and mutant mice vascular malformations respectively. Although mutations in the human Notch 3 gene caused a genetic form of vascular stroke and dementia, its role in arteriovenous malformations development has been unknown. In this study, we performed immunohistochemistry screening on tissue microarrays containing eight surgically resected human brain arteriovenous malformations and 10 control surgical epilepsy samples. The tissue microarrays were evaluated for Notch 1-4 expression. We have found that compared to normal brain vascular tissue Notch-3 was dramatically increased in brain arteriovenous malformations. Similarly, Notch 4 labelling was also increased in vascular malformations and was confirmed by western blot analysis. Notch 2 was not detectable in any of the human vessels analysed. Using both immunohistochemistry on microarrays and western blot analysis, we have found that Notch-1 expression was detectable in control vessels, and discovered a significant decrease of Notch 1 expression in vascular malformations. We have demonstrated that Notch 3 and 4, and not Notch 1, were highly increased in human arteriovenous malformations. Our findings suggested that Notch 4, and more importantly, Notch 3, may play a role in the development and pathobiology of human arteriovenous malformations

Internal Maxillary Artery-Middle Cerebral Artery Bypass: Infratemporal Approach for Subcranial-Intracranial (SC-IC) Bypass

BACKGROUND:Internal maxillary artery (IMax)-middle cerebral artery (MCA) bypass has been recently described as an alternative to cervical extracranial-intracranial bypass. This technique uses a keyhole craniectomy in the temporal fossa that requires a technically challenging end-to-side anastomosis.OBJECTIVE:To describe a lateral subtemporal craniectomy of the middle cranial fossa floor to facilitate wide exposure of the IMax to facilitate bypass.METHODS:Orbitozygomatic osteotomy is used followed by frontotemporal craniotomy and subsequently laterotemporal fossa craniectomy, reaching its medial border at a virtual line connecting the foramen rotundum and foramen ovale. The IMax was identified by using established anatomic landmarks, neuronavigation, and micro Doppler probe (Mizuho Inc. Tokyo, Japan). Additionally, we studied the approach in a cadaveric specimen in preparation for microsurgical bypass.RESULTS:There were 4 cases in which the technique was used. One bypass was performed for flow augmentation in a hypoperfused hemisphere. The other 3 were performed as part of treatment paradigms for giant middle cerebral artery aneurysms. Vein grafts were used in all patients. The proximal anastomosis was performed in an end-to-side fashion in 1 patient and end-to-end in 3 patients. Intraoperative graft flow measured with the Transonic flow probe ranged from 20 to 60 mL/min. Postoperative angiography demonstrated good filling of the graft with robust distal flow in all cases. All patients tolerated the procedure well.CONCLUSION:IMax to middle cerebral artery subcranial-intracranial bypass is safe and efficacious. The laterotemporal fossa craniectomy technique resulted in reliable identification and wide exposure of the IMax, facilitating the proximal anastomosis

Multilobar electrocorticography monitoring during intracranial aneurysm surgery

INTRODUCTION: To detect a neuronal threshold of tolerance to ischemia, the usefulness of multilobar electrocorticography (mEcoG) during intracranial aneurysm surgery was compared to the scalp EEG and correlated with the postoperative neurological status and the radiological findings. METHODS: Twenty-one patients harboring intracranial aneurysms were monitored by simultaneous scalp EEG and lobe-dependent mEcoG during surgical clipping. The patients were divided into group A (6 patients with no temporary clipping) and group B (15 patients with temporary clipping). RESULTS: New focal modifications of the mEcoG signal with high frequency (HF)-beta3 and delta waves were observed in none of the patients in group A and all of the patients in group B. These anomalies were followed by focal burst suppression pattern in eight cases (53%) in group B. These changes were detected in only two cases (9%) on the scalp EEG. New corticographic changes resolved in eight patients (53%) in group B. Among the seven patients in group B who had persistent focal burst pattern after clip removal, six (85%) presented with new neurological deficit or new hypodensity on CT. The Glasgow Outcome Scale was good (IV or V) in 85% of cases. CONCLUSION: mEcoG is more sensitive than scalp EEG. The appearance and persistence of the focal burst suppression pattern shown on mEcoG, was associated with a new neurological deficit or new hypodensity, whereas HF-beta3 or delta waves per se were not associated with new changes. A better comprehension of these EEG anomalies could determine the duration of temporary clipping and consequently influence the surgical strategy

Early Metabolic Flare in Squamous Cell Carcinoma after Chemotherapy is a Marker of Treatment Sensitivity In Vitro

PURPOSE: Early metabolic response with a decrease in glucose demand after cytotoxic treatment has been reported to precede tumor volume shrinkage. However, preclinical studies report of a very early rise in metabolism, a flare, following treatment. To elucidate these observations, we performed an experimental study on early metabolic response with sequential analysis of metabolic changes. METHODS: Three squamous cell carcinoma cell lines and one nontumorigenic cell line were exposed to cisplatin. The uptake of the fluorescent glucose analogue 2-NBDG was examined at days 1-6 using fluorescence microscopy. The relation between 2-NBDG-uptake and cell survival was evaluated. RESULTS: The tumor cells exhibited a high uptake of 2-NBDG, whereas the uptake in the nonmalignant cells was low. The more cisplatin sensitive cell lines exhibited a more pronounced metabolic flare than the less sensitive cell line. CONCLUSION: A metabolic flare was a very early sign of treatment response and potentially it could be used as an early marker of treatment sensitivity

Imaging oxygenation of human tumours

Tumour hypoxia represents a significant challenge to the curability of human tumours leading to treatment resistance and enhanced tumour progression. Tumour hypoxia can be detected by non-invasive and invasive techniques but the inter-relationships between these remains largely undefined. (18)F-MISO and Cu-ATSM-PET, and BOLD-MRI are the lead contenders for human application based on their non-invasive nature, ease of use and robustness, measurement of hypoxia status, validity, ability to demonstrate heterogeneity and general availability, these techniques are the primary focus of this review. We discuss where developments are required for hypoxia imaging to become clinically useful and explore potential new uses for hypoxia imaging techniques including biological conformal radiotherapy

Multislice CT angiography in the selection of patients with ruptured intracranial aneurysms suitable for clipping or coiling

Introduction We sought to establish whether CT angiography (CTA) can be applied to the planning and performance of clipping or coiling in ruptured intracranial aneurysms without recourse to intraarterial digital subtraction angiography (IA-DSA). Methods Over the period April 2003 to January 2006 in all patients presenting with a subarachnoid haemorrhage CTA was performed primarily. If CTA demonstrated an aneurysm, coiling or clipping was undertaken. IA-DSA was limited to patients with negative or inconclusive CTA findings. We compared CTA images with findings at surgery or coiling in patients with positive CTA findings and in patients with negative and inconclusive findings in whom IA-DSA had been performed. Results In this study, 224 consecutive patients (mean age 52.7 years, 135 women) were included. In 133 patients (59%) CTA demonstrated an aneurysm, and CTA was followed directly by neurosurgical (n=55) or endovascular treatment (n=78). In 31 patients (14%) CTA findings were categorized as inconclusive, and in 60 (27%) CTA findings were negative. One patient received surgical treatment on the basis of false-positive CTA findings. In 17 patients in whom CTA findings were inconclusive, IA-DSA provided further diagnostic information required for correct patient selection for any therapy. Five ruptured aneurysms in patients with a nonperimesencephalic SAH were negative on CTA, and four of these were also false-negative on IA-DSA. On a patient basis the positive predictive value, negative predictive value, sensitivity, specificity and accuracy of CTA for symptomatic aneurysms were 99%, 90%, 96%, 98% and 96%, respectively. Conclusion CTA should be used as the first diagnostic modality in the selection of patients for surgical or endovascular treatment of ruptured intracranial aneurysms. If CTA renders inconclusive results, IA-DSA should be performed. With negative CTA results the complementary value of IA-DSA is marginal. IA-DSA is not needed in patients with negative CTA and classic perimesencephalic SAH. Repeat IA-DSA or CTA should still be performed in patients with a nonperimesencephalic SAH

Imaging tumour hypoxia with positron emission tomography.

Hypoxia, a hallmark of most solid tumours, is a negative prognostic factor due to its association with an aggressive tumour phenotype and therapeutic resistance. Given its prominent role in oncology, accurate detection of hypoxia is important, as it impacts on prognosis and could influence treatment planning. A variety of approaches have been explored over the years for detecting and monitoring changes in hypoxia in tumours, including biological markers and noninvasive imaging techniques. Positron emission tomography (PET) is the preferred method for imaging tumour hypoxia due to its high specificity and sensitivity to probe physiological processes in vivo, as well as the ability to provide information about intracellular oxygenation levels. This review provides an overview of imaging hypoxia with PET, with an emphasis on the advantages and limitations of the currently available hypoxia radiotracers.Cancer Research UK (CRUK) funded the National Cancer Research Institute (NCRI) PET Research Working party to organise a meeting to discuss imaging cancer with hypoxia tracers and Positron Emission Tomography. IF was funded by CRUK and is also supported by the Chief Scientific Office. ALH is supported by CRUK and the Breast Cancer Research Foundation. RM is funded by NIHR Cambridge Biomedical Research Centre.This is the accepted manuscript. The final version is available from Nature Publishing at http://www.nature.com/bjc/journal/vaop/ncurrent/full/bjc2014610a.html

Imaging with non-FDG PET tracers: outlook for current clinical applications

Apart from the historical and clinical relevance of positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG), various other new tracers are gaining a remarkable place in functional imaging. Their contribution to clinical decision-making is irreplaceable in several disciplines. In this brief review we aimed to describe the main non-FDG PET tracers based on their clinical relevance and application for patient care