Use Of Brain Tissue Research Articles

Modeling Gamma Knife Radiosurgical Toxicity for Multiple Brain Metastases

Dosing for single fraction radiosurgery has traditionally relied on tumor measurements from a single maximum diameter. Most protocols recommend setting dosing criteria based on assumed risk of radionecrosis roughly correlating with tumor size. However, the risk of radionecrosis after radiosurgery is best modeled by a function of dose and volume treated, with the largest body of evidence supporting the use of brain tissue receiving ≥12 Gy in one fraction (V12, i.e., > 10.9 cm3). Here we show that tumor surface area (SA) and second order dimensions are superior predictors for Gamma Knife radiosurgical toxicity and can be used to estimate V12. A total of 1217 brain metastases from 245 patients treated with a prescribed dose from 13 to 27 Gy in one fraction were retrospectively reviewed. Eight independent modeling parameters were considered; 3 geometric tumor characteristics: SA, volume (V), and largest axial dimension (LAD) and 5 treatment planning variables: prescription dose (Rx), coverage, selectivity, gradient index, and number of shots. Linear regression and power-law formulations were performed to determine which parameters were the most accurate predictors of V12. The power model is dependent on a conceptualized "pseudo surface area" (PSA), defined as the surface area of a sphere with a diameter of LAD of a lesion (PSA = π*LAD2). At the aggregate patient level, the model predicts total brain V12 by summing the V12 values for each singular lesion only by using LAD and Rx as input variables. Tumor SA was the best univariate linear predictor of V12 (adjR2 = 0.770), followed by LAD (adjR2 = 0.755) and V (adjR2 = 0.745). The SA predictive model improves for lesions that have high sphericity > 0.85 (adjR2 = 0.837), with a measure of 1 indicating a perfect sphere. Using bivariable regression analysis, we formulated a single term power model that even more accurately predicts for V12 (V12 = 0.0137 * Rx1.5 * LAD2, adjR2 = 0.906) and is proportional to PSA. At the patient level, this model also accurately predicts for total brain V12 (adjR2 = 0.896) and V12 > 10.9 cm3 (Sensitivity = 99.1%, Specificity = 90.5%). Conceptually, SA univariately predicts for V12 more accurately than other tumor physical dimensions or treatment planning parameters, while the best bivariable power model involves PSA. We provide a preplan model for brain metastases that can help better estimate radionecrosis risk, determine prescription doses given a target V12, and provide safe dose escalation strategies without the use of any planning software.

Perceptions and attitudes towards companion animal brain banking in pet owners: A UK pilot study.

BackgroundDetailed analysis of archived brain tissue is fundamental to advancing the understanding of neurological disease. The development of the UK Brain Bank Network (UBBN) has provided an invaluable resource to facilitate such research in the human medical field. Similar resources are needed in veterinary medicine. However, collection and archiving of companion animal brain tissue is a potentially sensitive area for pet owners and veterinary professionals.MethodsUsing an online survey, we aimed to study pet owners’ perceptions of brain banking. The survey included information on respondents, their views on organ donation, the UBBN and the Royal Veterinary College's Companion Animal Brain Bank (RVC CABB).ResultsIn total 185 respondents were included. The use of brain tissue from pets for research was supported by 87% of respondents, and 66% of respondents felt that they were highly likely or likely to donate their pet's brain tissue to a CABB. Furthermore, 94% felt that more information on tissue banking in companion animals should be readily available.ConclusionsWe found that the perceptions of companion animal brain banking were positive in our respondents. Open dialogue and clear information provision on the process and benefits of the CABB could enhance awareness and thus facilitate brain donation for translational research.

Embryonic assembly of auditory circuits: spiral ganglion and brainstem

During early development, peripheral sensory systems generate physiological activity prior to exposure to normal environmental stimuli. This activity is thought to facilitate maturation of these neurons and their connections, perhaps even promoting efficacy or modifying downstream circuitry. In the mammalian auditory system, initial connections form at embryonic ages, but the functional characteristics of these early neural connections have not been assayed. We investigated processes of embryonic auditory development using a whole-head slice preparation that preserved connectivity between peripheral and brainstem stations of the auditory pathway. Transgenic mice expressing fluorescent protein provided observation of spiral ganglion and cochlear nucleus neurons to facilitate targeted electrophysiological recording. Here we demonstrate an apparent peripheral-to-central order for circuit maturation. Spiral ganglion cells acquire action potential-generating capacity at embryonic day 14 (E14), the earliest age tested, and action potential waveforms begin to mature in advance of comparable states for neurons of the ventral cochlear nucleus (VCN) and medial nucleus of the trapezoid body (MNTB). In accordance, auditory nerve synapses in the VCN are functional at E15, prior to VCN connectivity with the MNTB, which occurs at least 1 day later. Spiral ganglion neurons exhibit spontaneous activity at least by E14 and are able to drive third-order auditory brainstem neurons by E17. This activity precedes cochlear-generated wave activity by 4 days and ear canal opening by at least 2 weeks. Together, these findings reveal a previously unknown initial developmental phase for auditory maturation, and further implicate the spiral ganglion as a potential controlling centre in this process.

Laser Capture Microscopy (LCM) and real time RT‐PCR: Gene expression in PVN of transgenic vasopressin‐enhanced green fluorescent protein (VP‐eGFP) rats

Water deprivation decreases plasma volume and increases plasma osmolality and vasopressin (VP) release. Immunohistochemistry and in situ hybridization indicate that osmotic stimuli deplete magnocellular neurons of VP content, while increasing VP gene expression. The current experiments tested feasibility of using LCM and real time RT-PCR to evaluate mRNA expression in hypothalamic paraventricular nucleus (PVN) VP cells. Transgenic VP-eGFP Wistar rats were water deprived for 48 hrs. VP-eGFP expressing cells in the magnocellular PVN from euhydrated (E, n= 3) and dehydrated (D, n= 3) rats were identified in frozen hypothalamic sections (5 μm) with fluorescent microscopy and laser dissected (spot size~7.5 μm; power = 75mW) onto LCM caps (Arcturus). RNA was extracted, cDNA synthesized and real time RT-PCR was performed for mRNA’s of the ribosomal protein L-32 (housekeeper), and VP. Relative expression of VP was increased 3.5 X in the PVN of D compared to E rats. In contrast, expression of GAPDH (another housekeeping gene) relative to L-32 in PVN VP neurons was not different between D and E rats. Thus, the use of brain tissue from VP-eGFP rats circumvents potential RNA degradation during standard post-sectioning immunohistochemistry and allows for evaluation of mRNA expression of target genes in identified VP neurons. (NIH R01 HL36245, CMH and R01 HL68725, JES)

Early visual changes in reflected light on non-stained brain sections after focal ischemia mirror the area of ischemic damage

There is no reliable, simple method for delineation of ischemic regions at early time points after ischemia. We propose that at early times after stroke, ischemic regions can be visualized as a subtle change in reflected light directly in thaw-mounted, dried 20 μm brain sections. In 15 male Sprague–Dawley rats, anesthetized with isoflurane, middle cerebral artery transection and permanent bilateral common carotid artery occlusion was performed and brains were processed in five different ways. Areas of reflective change (RC) on non-stained sections were compared with areas on the adjacent sections delineated by microtubule associated protein 2 (MAP2) antibody, a reliable marker for early post-stroke, in five rats each at 1, 3, and 6 h after focal cerebral ischemia. A statistically significant correlation between ischemic areas (IA) measured on non-stained brain sections (IA RC) and adjacent sections immunostained (IM) with MAP2 Ab (IA IM) (IA RC=0.05+0.88·IA IM; R 2=0.8; n=15; P<0.01) and a small mean difference ±2 S.D. (−0.9±6.0%) indicated that the area measured on non-stained sections reflects the IA measured on MAP2 -IM sections. At 1 and 3 h after ischemia, the ratio between ischemic regions measured on the non-stained sections and on the adjacent sections immunostained with MAP2 Ab were not different from 100% (97.6±1.7%, 100.9±6.0%). At 6 h post-stroke, the IA measured on the non-stained sections was larger than on the IM sections (109.8±2.7%, P<0.01, compared to 100% ratio). Our study demonstrated that this quick and simple method for detection of damaged brain permitted the use of brain tissue for other assays and could be very useful for neuroprotective evaluation and for directed micro-sampling of brain tissue at early times after ischemia.

Behavioral testing does not exacerbate ischemic CA1 damage in gerbils.

Previous research studying ablative lesions has suggested that functional use may exacerbate brain injury. If true, this would have considerable ramifications not only for the mechanistic understanding of neuronal injury but also for the clinical use of physiotherapy. In this report the hypothesis that behavioral use of brain tissue exacerbates ischemic hippocampal injury was tested. Gerbils were subjected to sham operation or 5 minutes of normothermic ischemia. To produce borderline hippocampal CA1 injury and enhance susceptibility to exacerbation, 2 of 3 ischemic groups were cooled (>48 hours) beginning at 6 hours after ischemia. Increased use of the hippocampus was produced by a battery of tests involving 3 novel small mazes, a T maze, and an open field. One hypothermic group was not tested and served as a control. Behavioral testing failed to worsen ischemic damage since neuronal loss in the behaviorally tested and untested hypothermic groups was 12% and 8%, respectively, while that in the untreated ischemic group was 81% at a 1-month survival. Accordingly, protected CA1 cells tolerated the neuronal activity associated with behavioral testing. Concomitant with marked CA1 neuroprotection, a significant reduction in behavioral deficits with the hypothermic treatment was observed. Importantly, behavioral testing was found to transiently elevate brain temperature. CA1 neuronal survival was unaffected by behavioral testing or the associated mild fever. Hypothermia delayed for 6 hours provided sustainable CA1 neuroprotection.

The brain-mind quiddity: ethical issues in the use of human brain tissue for therapeutic and scientific purposes.

The use of human brain tissue in neuroscience research is increasing. Recent developments include transplanting neural tissue, growing or maintaining neural tissue in laboratories and using surgically removed tissue for...

Invasiveness of primary brain tumors.

Primary malignant neoplasms of the nervous system differ from other types of malignancy in several ways. Clinical progression is due to local invasive growth, while metastases outside the skull are rare. The tumors show no sharp delimitation from the surrounding normal tissue. At the edge, an ill-defined area of invasive tumor cells, reacting glial cells and inflammatory cells is present. At the same time the primary brain tumors are biologically heterogeneous. In this review, a short survey of markers for malignancy in primary brain tumors is given, and some properties of importance for invasive behavior, are listed. These include different cellular enzymes, phagocytotic property, locomotive and proliferative characteristics. Studies of primary brain tumors in situ show invasive growth into the surrounding brain tissue, often followed by hemorrhage and necrosis. In addition spread of tumor cells takes place along preexisting intracranial structures. Recently, several systems for the study of brain tumor invasiveness in culture have been elaborated. Both experimental and human gliomas have been tested. The target tissues include organ culture of embryonic chick heart muscle, chorioallantoic membrane, fetal rat brain tissue and reconstructed vessel walls. It has been shown that glioma cells are able to split junctions between normal cells. They destroy and phagocytose the normal cells and penetrate the normal tissue. The use of brain tissue and reaggregated brain cell cultures as target for glioma cells in culture opens the possibility for an elucidation of invasiveness as one of the most important properties of malignancy in the nervous system.