Elevated level of endothelin-1 in cerebrospinal fluid and lack of nitric oxide in basilar arterial plasma associated with cerebral vasospasm after subarachnoid haemorrhage in rabbits

Background: The role of endothelin-1 (ET-1) and nitric oxide (NO) as two important mediators in the development of cerebral vasospasm (CVS) after subarachnoid haemorrhage (SAH) is controversial. The objective of this study was to determine whether local levels of ET-1 and NO in cerebral arterial plasma and/or in cerebrospinal fluid (CSF) are associated with the occurrence of CVS after SAH. Methods: CVS was induced using the one-haemorrhage rabbit model and confirmed by digital subtraction angiography of the rabbits' basilar artery on day 5. Prior to sacrifice, local CSF and basilar arterial plasma samples were obtained by a transclival approach to the basilar artery. Systemic arterial plasma samples were obtained. ET-1 levels were determined by immunometric technique (pg/ml ± SEM) and total nitrate/nitrite level spectrophotometrically (µmol/l ± SEM). Findings: Angiographic CVS was documented after SAH induction (n = 12, P < 0.05). The ET-1 level in CSF was significantly elevated by 27.3% to 0.84 ± 0.08pg/ml in SAH animals (n = 7) in comparison to controls (0.66 ± 0.04pg/ml, n = 7, P < 0.05). There was no significant difference in ET-1 levels in systemic and basilar arterial plasma samples of SAH animals compared to controls. A significant lack of local NO metabolites was documented in basilar arterial plasma after SAH (36.8 ± 3.1µmol/l, n = 6) compared to controls (61.8 ± 6.2µmol/l, n = 6, P < 0.01). Conclusion: This study demonstrates that an elevated ET-1 level in CSF and local lack of NO in the basilar arterial plasma samples are associated with CVS after experimental SA

Prevention of delayed cerebral vasospasm by continuous intrathecal infusion of glyceroltrinitrate and nimodipine in the rabbit model in vivo

Objective: Intrathecal bolus administration of nitric oxide donors and calcium channel antagonists has been proposed to reduce cerebral vasospasm (CVS) in animal subarachnoid hemorrhage (SAH) models. Intrathecal continuous administration of these substances for CVS prevention has not been extensively evaluated. This study compared the efficacy of continuous intrathecal infusions of the NO donor glyceroltrinitrate and nimodipine in preventing delayed CVS associated with SAH in an animal model in vivo. Methods: New Zealand White rabbits were randomly assigned to six groups: no SAH/NaCl, no SAH/NO, no SAH/nimodipine, SAH/NaCl, SAH/NO, or SAH/nimodipine. Glyceroltrinitrate (GTN) at 0.5 μg/μl (0.5 μl/h) or nimodipine at 0.2 μg/μl (10 μl/h) or NaCl was continuously infused into the cisterna magna via an Alzet osmotic pump from day0 to day5 after injection of 1.0 ml autologous blood. The magnitude of spasm in the basilar artery was determined by comparison of pre- and posttreatment angiography and was calculated as proportional change in intraluminal diameter based on automatic measurements. Results: Atotal of 55 experiments and 110 angiograms were performed. SAH was associated with vasoconstriction of the basilar artery (SAH/NaCl group 19.85 ± 2.94%). Continuous intrathecal injection of GTN and nimodipine prevented SAH-induced CVS. There was significant prevention of CVS in animals treated with GTN (SAH/NO group 5.93 ± 5.2%, n = 11) and nimodipine (SAH/nimodipine group: 0.55 ± 2.66%, n = 9). There was no significant difference between the treatment groups and controls in prevention of CVS. Conclusions: This study demonstrates that prophylactic continuous intrathecal administration of either GTN or nimodipine equally prevents SAH-associated CVS in an animal mode

Norepinephrine-induced hypertension dilates vasospastic basilar artery after subarachnoid haemorrhage in rabbits

Background: Vasopressor-induced hypertension is routinely indicated for prevention and treatment of cerebral vasospasm (CVS) after subarachnoid haemorrhage (SAH). Mechanisms underlying patients' clinical improvement during vasopressor-induced hypertension remain incompletely understood. The aim of this study was to evaluate angiographic effects of normovolaemic Norepinephrine (NE)-induced hypertension therapy on the rabbit basilar artery (BA) after SAH. Methods: Cerebral vasospasm was induced using the one-haemorrhage rabbit model; sham-operated animals served as controls. Five days later the animals underwent follow-up angiography prior to and during NE-induced hypertension. Changes in diameter of the BA were digitally calculated in mean µm ± SEM (standard error of mean). Findings: Significant CVS of 14.2% was documented in the BA of the SAH animals on day 5 compared to the baseline angiogram on day 0 (n = 12, p  0.05). During systemic administration of NE, mean arterial pressure increased from 70.0 ± 1.9mmHg to 136.0 ± 2.1mmHg in the SAH group (n = 12, p < 0.001) and from 72.0 ± 3.1 to 137.8 ± 1.3 in the control group (n = 12, p < 0.001). On day 5 after SAH, a significant dilatation of the BA in response to norepinephrine could be demonstrated in both groups. The diameter of the BA in the SAH group increased from 640.5 ± 17.5 µm to 722.5 ± 23.7 µm (n = 12, p < 0.05; ). In the control group the diameter increased from 716.8 ± 15.5 µm to 779.9 ± 24.1 µm (n = 12, p < 0.05). Conclusion: This study demonstrated that NE-induced hypertension causes angiographic dilatation of the BA in the SAH rabbit model. Based on these observations, it can be hypothesised that clinical improvement during vasopressor-induced hypertension therapy after SAH might be explained with cerebral vasodilatation mechanisms that lead to improvement of cerebral blood flo

Prevention of delayed cerebral vasospasm by continuous intrathecal infusion of glyceroltrinitrate and nimodipine in the rabbit model in vivo

OBJECTIVE: Intrathecal bolus administration of nitric oxide donors and calcium channel antagonists has been proposed to reduce cerebral vasospasm (CVS) in animal subarachnoid hemorrhage (SAH) models. Intrathecal continuous administration of these substances for CVS prevention has not been extensively evaluated. This study compared the efficacy of continuous intrathecal infusions of the NO donor glyceroltrinitrate and nimodipine in preventing delayed CVS associated with SAH in an animal model in vivo. METHODS: New Zealand White rabbits were randomly assigned to six groups: no SAH/NaCl, no SAH/NO, no SAH/nimodipine, SAH/NaCl, SAH/NO, or SAH/nimodipine. Glyceroltrinitrate (GTN) at 0.5 microg/microl (0.5 microl/h) or nimodipine at 0.2 microg/microl (10 microl/h) or NaCl was continuously infused into the cisterna magna via an Alzet osmotic pump from day 0 to day 5 after injection of 1.0 ml autologous blood. The magnitude of spasm in the basilar artery was determined by comparison of pre- and posttreatment angiography and was calculated as proportional change in intraluminal diameter based on automatic measurements. RESULTS: A total of 55 experiments and 110 angiograms were performed. SAH was associated with vasoconstriction of the basilar artery (SAH/NaCl group 19.85+/-2.94%). Continuous intrathecal injection of GTN and nimodipine prevented SAH-induced CVS. There was significant prevention of CVS in animals treated with GTN (SAH/NO group 5.93+/-5.2%, n=11) and nimodipine (SAH/nimodipine group: 0.55+/-2.66%, n=9). There was no significant difference between the treatment groups and controls in prevention of CVS. CONCLUSIONS: This study demonstrates that prophylactic continuous intrathecal administration of either GTN or nimodipine equally prevents SAH-associated CVS in an animal model

Rapid, label-free classification of glioblastoma differentiation status combining confocal Raman spectroscopy and machine learning

Label-free identification of tumor cells using spectroscopic assays has emerged as a technological innovation with a proven ability for rapid implementation in clinical care. Machine learning facilitates the optimization of processing and interpretation of extensive data, such as various spectroscopy data obtained from surgical samples. The here-described preclinical work investigates the potential of machine learning algorithms combining confocal Raman spectroscopy to distinguish non-differentiated glioblastoma cells and their respective isogenic differentiated phenotype by means of confocal ultra-rapid measurements. For this purpose, we measured and correlated modalities of 1146 intracellular single-point measurements and sustainingly clustered cell components to predict tumor stem cell existence. By further narrowing a few selected peaks, we found indicative evidence that using our computational imaging technology is a powerful approach to detect tumor stem cells in vitro with an accuracy of 91.7% in distinct cell compartments, mainly because of greater lipid content and putative different protein structures. We also demonstrate that the presented technology can overcome intra- and intertumoral cellular heterogeneity of our disease models, verifying the elevated physiological relevance of our applied disease modeling technology despite intracellular noise limitations for future translational evaluatio

Artificial-intelligence-based molecular classification of diffuse gliomas using rapid, label-free optical imaging

Molecular classification has transformed the management of brain tumors by enabling more accurate prognostication and personalized treatment. However, timely molecular diagnostic testing for patients with brain tumors is limited, complicating surgical and adjuvant treatment and obstructing clinical trial enrollment. In this study, we developed DeepGlioma, a rapid ($< 90$ seconds), artificial-intelligence-based diagnostic screening system to streamline the molecular diagnosis of diffuse gliomas. DeepGlioma is trained using a multimodal dataset that includes stimulated Raman histology (SRH); a rapid, label-free, non-consumptive, optical imaging method; and large-scale, public genomic data. In a prospective, multicenter, international testing cohort of patients with diffuse glioma ($n=153$) who underwent real-time SRH imaging, we demonstrate that DeepGlioma can predict the molecular alterations used by the World Health Organization to define the adult-type diffuse glioma taxonomy (IDH mutation, 1p19q co-deletion and ATRX mutation), achieving a mean molecular classification accuracy of $93.3\pm 1.6\%$. Our results represent how artificial intelligence and optical histology can be used to provide a rapid and scalable adjunct to wet lab methods for the molecular screening of patients with diffuse glioma.Comment: Paper published in Nature Medicin

Dynamic F-18-FDG PET Lymphography for In Vivo Identification of Lymph Node Metastases in Murine Melanoma

Positron lymphography using F-18-FDG followed by Cerenkov-guided resection of lymph nodes in healthy mice has previously been introduced by our group. Our aim in this study was to further assess the technique's potential beyond merely localizing sentinel lymph nodes. We now aimed to evaluate the potential of positron lymphography to characterize the nodes with respect to their tumor status in order to identify metastatic lymph nodes. We explored whether metastatic nodes could be distinguished from normal nodes via dynamic F-18-FDG lymphography, to then be resected under Cerenkov imaging guidance. Methods: A murine melanoma cell line highly metastatic to lymph nodes (B16F10) was implanted subcutaneously on the dorsal hind paw of C57 mice while the tumor-free contralateral leg served as an intraindividual control. A model of reactive lymph nodes after concanavalin A challenge served as an additional control to provide nonmalignant inflammatory lymphadenopathy. Dynamic PET/CT imaging was performed immediately after injection of F-18-FDG around the tumor or intracutaneously in the contralateral footpad. Furthermore, PET/CT and Cerenkov studies were performed repeatedly over time to follow the course of metastatic spread. In selected mice, popliteal lymph nodes underwent Cerenkov luminescence imaging. Hematoxylin and eosin staining was done to verify the presence of lymphatic melanoma infiltration. Results: Positron lymphography using F-18-FDG was successfully performed on tumor-bearing and non-tumor-bearing mice, as well as on controls bearing sites of inflammation; the results clearly identified the sentinel lymph node basin and delineated the lymphatic drainage. Significantly prolonged retention of activity was evident in metastatic nodes as compared with controls without tumor. On the basis of these results, the contrast in detection and identification of metastatic lymph nodes was distinct and could be used for guided lymph node resection, such as by using Cerenkov luminescence imaging. However, retention after F-18-FDG lymphography was also seen in acute inflammatory lymphadenopathy. Conclusion: In a tumor model, significantly longer retention of the radiotracer during F-18-FDG lymphography was seen in metastatic than nonmetastatic lymph nodes, allowing for differentiation between the two and for selective resection of tumor-bearing nodes using Cerenkov imaging. Inflammation can be better differentiated in a subacute state

Comparison between routine cylindrical cerebral aneurysm volume approximation and three-dimensional volume measurements in experimental aneurysms.

OBJECTIVES Aneurysm volume is routinely approximated calculating cylindrical volumes. Exact aneurysm volume assessment is crucial for liquid polymer embolization. The aim of this study was to compare simple cylindrical volume approximations with direct multiplanar reconstruction (MPR) segmentational volumetry in a saccular/complex experimental rabbit bifurcation aneurysm model. METHODS In 12 female New Zealand white rabbits, saccular, broad-based, bilobular, and bisaccular aneurysms (three of each) were created using the rabbit venous pouch bifurcation model. Contrast-enhanced magnetic resonance angiography (CE-MRA) was performed, and maximal intensity projection (MIP) reconstructions as well as an MPR dataset were acquired. Aneurysm width and length were measured in MIP images, and the volume was approximated calculating cylindrical volumes. Three-dimensional (3D) segmentational volumetry using the MPR dataset was performed in a semi-automated manner. RESULTS Maximal intensity projection cylindrical volumes ranged from 53·6 to 503·5 mm(3) (mean 186·5±118 mm(3)). Multiplanar reconstruction segmentation-based volumes ranged from 74·7 to 581·0 mm(3) (mean 202·2±133 mm(3)). The mean relative difference between MIP cylindrical and MPR segmentation volume calculation was 24·7% (range -77·5 to +50·8%). Only 4 of 12 MPR segmentational volumes were within a 10% range of results calculated for MIP cylindrical volume, and 3 of those were in broad-based aneurysms. CONCLUSION This descriptive study demonstrates that estimated MIP cylindrical volumes differ from those measured by MPR segmentation volumetry. With the increasing acquisition of 3D data as 3D-MRA and the increasing need for exact volume determination, studies on the accuracy of computational segmentational volumetry of CE-MRA are necessary

Aneurysm Volume in the Rabbit Bifurcation Model-Calculation with Cylindric Volume Formula versus Multiplanar Reconstruction-Volumetry in Contrast-Enhanced Magnet Resonance Angiography

Background: So far, aneurysm volume was expressed by using aneurysm width and length. Using these parameters received from magnetic resonance angiography (MRA)- maximum intensity projection (MIP) images, volume of aneurysms was estimated using the cylindric volume formula: (3.14×[width/2]2×length). Determination of exact aneurysm volume gains importance in testing liquid embolic polymers. We compare the calculatively derived volume in saccular, bilobular, broad-based, or bisaccular aneurysms of the rabbit bifurcation model with MPR segmentational volumetry. Methods: In 12 female New Zealand white rabbits three of each saccular, broad-based, bilobular, and bisaccular aneurysms were created using the rabbit venous pouch bifurcation model. Contrast-enhanced magnetic resonance angiography (CE-MRA) was performed. For all aneurysms and MIP reconstructions as well as an MPR dataset acquired. Aneurysm width and length were measured in MIP images, and the volume was calculated using the cylindrical volume formula. Three-dimensional (3-D) segmentational volumetry using the MPR dataset was in a semiautomated manner. Results: The 12 aneurysms had a calculated volume ranging from 53.6 to 503.5 mm3 (mean 186.5±118 mm3) and the MPR segmentational volume ranging from 74.7 to 581.0 mm3 (mean 202.2±133 mm3). The mean relative difference to the MIP cylindrical volume calculation was 24.7% (range, −77.5±50.8). Only 4 of 12 of the MPR segmentational volumes were within the 10% range of cylindrical volume calculated results, three of these were in broad-based aneurysms. Conclusions: This descriptive study demonstrates that an approximate calculation of aneurysm volume from MRA-MIP images show high differences to MPR segmentational volumetry. With the increasing acquisition of 3-D data as 3-D-MRA and the rising need of exact volume determination, studies on the accuracy of computational segmentational volumetry of CE-MRA have to be undertaken