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Edjah K. Nduom, Stuart Walbridge, and Russell R. Lonser

Object

Although pulsatile and continuous infusion paradigms have been described for convective delivery of drugs, the effectiveness and properties of each flow paradigm are unknown. To determine the effectiveness and properties of pulsatile and continuous convective infusion paradigms, the authors compared these convective flow methods in the gray and white matter of primates.

Methods

Six primates (Macaca mulatta) underwent convective infusion of Gd-DPTA (5 mM) into the cerebral gray matter (thalamus) or white matter (frontal lobe) using pulsed (intermittent pulses of 15 μl/min) or continuous (1 μl/min) convective flow. Results were assessed by clinical MRI and histological analyses.

Results

Distribution of Gd-DTPA infusate in gray and white matter by pulsed and continuous flow was clearly identified using MRI, which revealed that both convective flow methods demonstrated an increase in the volume of distribution (Vd) with increasing volume of infusion (Vi) in the surrounding gray and white matter. Although the mean (± SD) gray matter Vd:Vi ratio for the pulsed infusions (4.2 ± 0.5) was significantly lower than the mean Vd:Vi ratio for continuous infusions (5.4 ± 0.5; a 22% difference [p = 0.0006]), the difference between pulsed (3.8 ± 0.4) and continuous (4.3 ± 1.2) infusions in white matter was not significantly different (p = 0.3). Pulsed infusions were associated with more leakback (12.3% ± 6.4% of Vi) than continuous infusions (3.9% ± 7.8%), although this difference was not significant (p = 0.2). All animals tolerated the infusions and there was no histological evidence of tissue injury at the infusion sites.

Conclusions

Although pulsed and continuous infusion flow paradigms can be safely and effectively used for convective delivery into both gray and white matter, continuous infusion is associated with a higher Vd:Vi ratio than pulsatile infusion in gray matter. High rates of infusion (15 μl/min) can be used to deliver infusate without any significant leakback and without any clinical or histological evidence of injury.

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Edjah K. Nduom, Chunzhang Yang, Marsha J. Merrill, Zhengping Zhuang, and Russell R. Lonser

Object

The astrocytic contribution to the blood-brain barrier (BBB) in metastatic and primary malignant brain tumors is not well understood. To better understand the vascular properties associated with metastatic and primary malignant brain tumors, the authors systematically analyzed the astrocytic component of the BBB in brain neoplasms.

Methods

Twelve patients who underwent resection of metastatic or primary brain neoplasms (4 metastatic lesions, 2 low-grade astrocytomas, 2 anaplastic astrocytomas, and 4 glioblastoma multiforme) were included. Clinical, MRI, operative, histopathological and immunohistochemical (glial fibrillary acidic protein [GFAP], CD31, and aquaporin 4 [AQ4]) findings were analyzed.

Results

Intratumoral regions of MRI enhancement corresponded with breakdown of the normal astrocyte–endothelial cell relationship in the BBB in metastatic deposits and malignant gliomas. Metastases demonstrated lack of perivascular GFAP and AQ4 on CD31-positive intratumoral vessels. At the metastasis-brain interface, normalization of GFAP and AQ4 staining associated with intraparenchymal vessels was observed. Intratumoral vasculature in enhancing regions of high-grade gliomas revealed gaps in GFAP and AQ4 staining consistent with disintegration of the normal astrocyte–endothelial cell association in the BBB. Intratumoral vasculature in low-grade and nonenhancing regions of high-grade gliomas maintained the normal astrocyte–endothelial cell relationship seen in an intact BBB, with GFAP- and AQ4-positive glial processes that were uniformly associated with the CD31-positive vasculature.

Conclusions

Regions of MRI enhancement in metastatic and primary malignancies correspond to areas of breakdown of the physiological astrocyte–endothelial cell relationship of the BBB, including loss of normal perivascular astrocytic architecture on GFAP and AQ4 immunohistochemistry. Nonenhancing areas are associated with preservation of the normal astrocyte–endothelial cell relationship of the intact BBB.

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Dueng-Yuan Hueng and Huey-Kang Sytwu

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Nima Hamidi, Brij Karmur, Stephanie Sperrazza, Julia Alexieva, Liz Salmi, Brad E. Zacharia, Edjah K. Nduom, Aaron A. Cohen-Gadol, James T. Rutka, and Alireza Mansouri

OBJECTIVE

Effective use of social media (SM) by medical professionals is vital for better connections with patients and dissemination of evidence-based information. A study of SM utilization by different stakeholders in the brain tumor community may help determine guidelines for optimal use.

METHODS

Facebook, Twitter, and YouTube were searched by using the term “Brain Tumor.” Platform-specific metrics were determined, including audience size, as a measure of popularity, and mean annual increase in audience size, as a measure of performance on SM. Accounts were categorized on the basis of apparent ownership and content, with as many as two qualitative themes assigned to each account. Correlations of content themes and posting behavior with popularity and performance metrics were assessed by using the Pearson’s test.

RESULTS

Facebook (67 pages and 304,581 likes) was predominantly used by organizations (64% of pages). Top themes on Facebook, Twitter, and YouTube were charity and fundraising (67% of pages), education and research (72% of accounts), and experience sharing and support seeking (48% of videos, 60% of views, and 82% of user engagement), respectively. On Facebook, only the presence of other concurrent platforms influenced a page’s performance (rho = 0.59) and popularity (rho = 0.61) (p < 0.05). On Twitter, the number of monthly tweets (rho = 0.66) and media utilization (rho = 0.78) were significantly correlated with increased popularity and performance (both p < 0.05). Personal YouTube videos (30% of videos and 61% of views) with the theme of experience sharing and support seeking had the highest level of engagement (60% of views, 70% of comments, and 87% of likes).

CONCLUSIONS

Popularity and prevalence of qualitative themes differ among SM platforms. Thus, optimal audience engagement on each platform can be achieved with thematic considerations. Such considerations, along with optimal SM behavior such as media utilization and multiplatform presence, may help increase content popularity and thus increase community access to neurooncology content provided by medical professionals.

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Langston T. Holly, William W. Ashley Jr., Edjah K. Nduom, Brenton Pennicooke, Caple A. Spence, and Babu G. Welch

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Nima Hamidi, Brij Karmur, Stephanie Sperrazza, Julia Alexieva, Liz Salmi, Brad E. Zacharia, Edjah K. Nduom, Aaron A. Cohen-Gadol, James T. Rutka, and Alireza Mansouri

OBJECTIVE

Effective use of social media (SM) by medical professionals is vital for better connections with patients and dissemination of evidence-based information. A study of SM utilization by different stakeholders in the brain tumor community may help determine guidelines for optimal use.

METHODS

Facebook, Twitter, and YouTube were searched by using the term “Brain Tumor.” Platform-specific metrics were determined, including audience size, as a measure of popularity, and mean annual increase in audience size, as a measure of performance on SM. Accounts were categorized on the basis of apparent ownership and content, with as many as two qualitative themes assigned to each account. Correlations of content themes and posting behavior with popularity and performance metrics were assessed by using the Pearson’s test.

RESULTS

Facebook (67 pages and 304,581 likes) was predominantly used by organizations (64% of pages). Top themes on Facebook, Twitter, and YouTube were charity and fundraising (67% of pages), education and research (72% of accounts), and experience sharing and support seeking (48% of videos, 60% of views, and 82% of user engagement), respectively. On Facebook, only the presence of other concurrent platforms influenced a page’s performance (rho = 0.59) and popularity (rho = 0.61) (p < 0.05). On Twitter, the number of monthly tweets (rho = 0.66) and media utilization (rho = 0.78) were significantly correlated with increased popularity and performance (both p < 0.05). Personal YouTube videos (30% of videos and 61% of views) with the theme of experience sharing and support seeking had the highest level of engagement (60% of views, 70% of comments, and 87% of likes).

CONCLUSIONS

Popularity and prevalence of qualitative themes differ among SM platforms. Thus, optimal audience engagement on each platform can be achieved with thematic considerations. Such considerations, along with optimal SM behavior such as media utilization and multiplatform presence, may help increase content popularity and thus increase community access to neurooncology content provided by medical professionals.