Acute changes of pro-inflammatory markers and corticosterone in experimental subarachnoid haemorrhage: A prerequisite for severity assessment.

Many details of the pathophysiology of subarachnoid haemorrhage (SAH) still remain unknown, making animal experiments an indispensable tool for assessment of diagnostics and therapy. For animal protection and project authorization, one needs objective measures to evaluate the severity and burden in each model. Corticosterone is described as a sensitive stress parameter reflecting the acute burden, and inflammatory markers can be used for assessment of the extent of the brain lesion. However, the brain lesion itself may activate the hypothalamic-pituitary-adrenal-axis early after SAH, as shown for ischemic stroke, probably interfering with early inflammatory processes, thus complicating the assessment of severity and burden on the basis of corticosterone and inflammation. To assess the suitability of these markers in SAH, we evaluated the courses of corticosterone, IL-6 and TNF-α up to 6h in an acute model simulating SAH in continuously anaesthetized rats, lacking the pain and stress induced impact on these parameters. Animals were randomly allocated to sham or SAH. SAH was induced by cisterna magna blood-injection, and intracranial pressure and cerebral blood flow were measured under continuous isoflurane/fentanyl anaesthesia. Withdrawn at predetermined time points, blood was analysed by commercial ELISA kits. After 6h the brain was removed for western blot analysis of IL-6 and TNF-α. Serum corticosterone levels were low with no significant difference between sham and SAH. No activation of the HPA-axis was detectable, rendering corticosterone a potentially useful parameter for stress assessment in future chronic studies. Blood IL-6 and TNF-α increased in both groups over time, with IL-6 increasing significantly more in SAH compared to sham towards the end of the observation period. In the basal cortex, IL-6 and TNF-α increased only in SAH. The pro-inflammatory response seems to start locally in the brain, reflected by an increase in peripheral blood. An additional surgery-induced systemic inflammatory response should be considered.

Assessment of cerebral hemodynamics during neurosurgical procedures using laser speckle image analysis.

Aneurysmal subarachnoid hemorrhage (aSAH) is a severe medical condition associated with a significant cause of mortality throughout the world. Cisterna magna injection model is accepted widely to mimic clinical aSAH and is performed on small animal models to study aSAH during neurosurgery. Coherent light scattered from the surface of the rat brain is used to infer information about the variations in blood flow during this condition. We obtained speckle images from the exposed cortex during the entire experiment using an external tissue imaging system. Contrast and fractal analyses are carried out for the recorded speckle pattern time series. Correlation analysis based on Hurst exponent for these images is found to be a more sensitive tool in studying aSAH as compared to routinely used laser speckle contrast analysis for assessing the changes in blood flow velocity. Additionally, our studies provide improved blood flow detection sensitivity with image Hurst exponent in combination with computed fractal dimension, during an event of aSAH.

Can acoustic structural quantification be used to characterize the ultrasound echotexture of the peripheral zone of breast lesions?

BACKGROUND: Besides mammography, breast ultrasound is the most important imaging modality for women with suspected breast cancer. New software tools bear high potential for improved detectability and specification of malignant breast lesions. OBJECTIVE: To compare the halo depicted around malignant breast lesions by ultrasound using Acoustic Structure Quantification (ASQ) of raw image data with the echogenic rim seen in B-mode ultrasound. METHODS: This retrospective study included 37 women for whom conventional B-mode ultrasound of the breast and ASQ were available as well as histopathology findings for comparison. Software tools were used to measure the halo area or echogenic rim and tumor area and calculate halo-to-lesion ratios for the two ultrasound modes. Six inexperienced readers characterized the breast lesions based on this information. Specificity, sensitivity, positive predictive value (PPV), and negative predictive value (NPV) were determined. ANOVA, the Wilcoxon test, and ROC curve analysis were performed. RESULTS: There was a linear relationship between ASQ-based and B-mode-based halo-to-lesion ratios; however, a systematic error was also noted. ASQ-derived ratios tended to be higher for breast lesions with lymphangioinvasion (p = 0.051, n.s.) and higher N-stages (p > 0.925, n.s.), while there was no correlation with other markers. Because of the significantly greater conspicuity of peritumoral halos in the ASQ mode, inexperienced readers achieved greater sensitivity (78% vs. 74%) and specificity (75% vs. 71%) and higher NPVs (75% vs. 71%) and PPVs (78% vs. 74%) compared with B-mode images. Greater halo conspicuity affected the identification of malignant lesions with both modes; ASQ was found to be particularly well suited (FBimage (1,100) = 19.253, p < 0.001; FASQ (1,100) = 52.338, p < 0.001). The inexperienced readers were significantly more confident about their diagnosis using the ASQ maps (z = -3.023, p = 0.003). CONCLUSIONS: We conclude that the halo in ASQ and the echogenic rim in B-mode ultrasound are attributable to different morphologic correlates. ASQ improves diagnostic accuracy and confidence of inexperienced examiners because of improved halo visibility.

The Acute Phase of Experimental Subarachnoid Hemorrhage: Intracranial Pressure Dynamics and Their Effect on Cerebral Blood Flow and Autoregulation.

Clinical presentation and neurological outcome in subarachnoid hemorrhage (SAH) is highly variable. Aneurysmal SAH (aSAH) is hallmarked by sudden increase of intracranial pressure (ICP) and acute hypoperfusion contributing to early brain injury (EBI) and worse outcome, while milder or non-aneurysmal SAH with comparable amount of blood are associated with better neurological outcome, possibly due to less dramatic changes in ICP. Acute pressure dynamics may therefore be an important pathophysiological aspect determining neurological complications and outcome. We investigated the influence of ICP variability on acute changes after SAH by modulating injection velocity and composition in an experimental model of SAH. Five hundred microliters of arterial blood (AB) or normal saline (NS) were injected intracisternally over 1 (AB1, NS1), 10 (AB10, NS10), or 30 min (AB30) with monitoring for 6 h (n = 68). Rapid blood injection resulted in highest ICP peaks (AB1 median 142.7 mmHg [1.Q 116.7-3.Q 230.6], AB30 33.42 mmHg [18.8-38.3], p < 0.001) and most severe hypoperfusion (AB1 16.6% [11.3-30.6], AB30 44.2% [34.8-59.8]; p < 0.05). However, after 30 min, all blood groups showed comparable ICP elevation and prolonged hypoperfusion. Cerebral autoregulation was disrupted initially due to the immediate ICP increase in all groups except NS10; only AB1, however, resulted in sustained impairment of autoregulation, as well as early neuronal cell loss. Rapidity and composition of hemorrhage resulted in characteristic hyperacute hemodynamic changes, with comparable hypoperfusion despite different ICP ranges. Only rapid ICP increase was associated with pronounced and early, but sustained disruption of cerebral autoregulation, possibly contributing to EBI.

The plasticity of primary microglia and their multifaceted effects on endogenous neural stem cells in vitro and in vivo.

BACKGROUND: Microglia-the resident immune cells of the brain-are activated after brain lesions, e.g., cerebral ischemia, and polarize towards a classic "M1" pro-inflammatory or an alternative "M2" anti-inflammatory phenotype following characteristic temporo-spatial patterns, contributing either to secondary tissue damage or to regenerative responses. They closely interact with endogenous neural stem cells (NSCs) residing in distinct niches of the adult brain. The current study aimed at elucidating the dynamics of microglia polarization and their differential effects on NSC function. RESULTS: Primary rat microglia in vitro were polarized towards a M1 phenotype by LPS, or to a M2 phenotype by IL4, while simultaneous exposure to LPS plus IL4 resulted in a hybrid phenotype expressing both M1- and M2-characteristic markers. M2 microglia migrated less but exhibit higher phagocytic activity than M1 microglia. Defined mediators switched microglia from one polarization state to the other, a process more effective when transforming M2 microglia towards M1 than vice versa. Polarized microglia had differential effects on the differentiation potential of NSCs in vitro and in vivo, with M1 microglia promoting astrocytogenesis, while M2 microglia supported neurogenesis. Regardless of their polarization, microglia inhibited NSC proliferation, increased NSC migration, and accelerated NSC differentiation. CONCLUSION: Overall, this study shed light on the complex conditions governing microglia polarization and the effects of differentially polarized microglia on critical functions of NSCs in vitro and in vivo. Refining the understanding of microglia activation and their modulatory effects on NSCs is likely to facilitate the development of innovative therapeutic concepts supporting the innate regenerative capacity of the brain.

Bioluminescence imaging visualizes osteopontin-induced neurogenesis and neuroblast migration in the mouse brain after stroke.

BACKGROUND: Osteopontin (OPN), an acidic phosphoglycoprotein, is upregulated in the brain after cerebral ischemia. We previously reported that OPN supports migration, survival, and proliferation of neural stem cells (NSC) in primary cell culture, as well as their differentiation into neurons. We here analyzed the effects of OPN on neuroblasts in vivo in the context of cerebral ischemia. METHODS: Transgenic mice expressing luciferase under the control of the neuroblast-specific doublecortin (DCX)-promoter, allowing visualization of neuroblasts in vivo using bioluminescence imaging (BLI), were injected with OPN intracerebroventricularly while control mice were injected with vehicle buffer. To assess the effects of OPN after ischemia, additional mice were subjected to photothrombosis and injected with either OPN or vehicle. RESULTS: OPN enhanced the migration of neuroblasts both in the healthy brain and after ischemia, as quantified by BLI in vivo. Moreover, the number of neural progenitors was increased following OPN treatment, with the maximum effect on the second day after OPN injection into the healthy brain, and 14 days after OPN injection following ischemia. After ischemia, OPN quantitatively promoted the endogenous, ischemia-induced neuroblast expansion, and additionally recruited progenitors from the contralateral hemisphere. CONCLUSIONS: Our results strongly suggest that OPN constitutes a promising substance for the targeted activation of neurogenesis in ischemic stroke.

Embolization of a life-threatening placenta increta hemorrhage with a four-month MRI follow-up.

A 29-year-old woman with partial placenta increta was treated by bilateral uterine artery embolization (UAE) for bleeding with hemorrhagic shock two months after delivery, resulting in permanent hemostasis. The patient underwent a total of three magnetic resonance imaging (MRI) examinations-before UAE and four days and four months after UAE. At four months, MRI showed a fully regenerated uterus with preserved perfusion and complete resolution of residual placental tissue.