FP2-6 Modelling neonatal intraventricular haemorrhage using organotypic samples from the wall of the lateral ventricle

Objectives

Intraventricular Haemorrhage (IVH) impacts on ependyma and neural stem cells (NSC) within the subventricular zone.1 Developing therapeutic interventions to curtail this impact is a key research goal. Organotypic models from the wall of the lateral ventricle (LV) of mice2 and humans have the potential to offer unique insight into the dynamic impact of IVH.

Design

Basic science research using whole mount preparations (WMP) from the wall of the LV from mice and humans (SOLVe trial: IRAS ID 247936).

Subjects

Transgenic mouse line: Fucci:hGFAPCreER:TomatoTD. Human samples from children undergoing surgery for medically intractable epilepsy.

Methods

Using a published protocol2 WMP of the LV were prepared. Two samples of human CSF were acquired: a ‘haemorrhagic’ sample from a neonate with IVH and a ‘clean’ sample from a newborn undergoing repair of myelomeningocele. 72 hours time-lapse confocal microscopy was undertaken from multiple wells.

Results

Colocalisation of GFP (Fucci+ve) in hGFAP +ve (RFP +ve) cells revealed dividing NSC within the wall of the LV. Quantification of fucci +ve cells revealed ‘haemorrhagic’ CSF caused a significant reduction in proliferation whilst ‘clean’ CSF caused a significant increase in early proliferation.

Conclusions

Organotypic slice preparation from mice and human lateral ventricle represents a novel approach to investigating the impact of IVH on the wall of the lateral ventricle.

References

Back SA, Miller SP. Brain injury in premature neonates: A primary cerebral dysmaturation disorder? Ann Neurol 2014 April;75(4):469–86.

Obernier K, Cebrian-Silla A, Thomson M, Parraguez JI, Anderson R, Guinto C, Rodas Rodriguez J, Garcia-Verdugo JM, Alvarez-Buylla A. Adult neurogenesis is sustained by symmetric self-renewal and differentiation. Cell Stem Cell2018February 1;22(2):221–234.

Free phenytoin concentration measurement in brain extracellular fluid: a pilot study

This article investigates the relationship between brain extracellular fluid free phenytoin concentration and plasma free phenytoin concentration in adults with acute brain injury. Daily cerebral microdialysate free phenytoin concentration was measured in eight adults with acute brain injury and compared with simultaneous measurement of plasma free phenytoin concentration. The group data revealed no significant correlation between microdialysate and plasma free phenytoin concentration (r = 0.34, p = 0.41). However, in two patients, with a sufficient number of samples for intra-individual analysis, there was a significant correlation between microdialysate and plasma free phenytoin concentration (r = 0.92, p < 0.001 and r = 0.88, p < 0.01). In vitro microdialysis relative recovery for phenytoin was 2.1%. In the context of acute brain injury, measurement of free plasma phenytoin concentration may not provide an accurate reflection of regional brain extracellular fluid free phenytoin concentration and may have limitations with respect to achieving reproducible brain extracellular fluid free phenytoin concentrations. This has implications for dosing regimens relying on plasma phenytoin levels.

Improving the recovery of S100B protein in cerebral microdialysis: implications for multimodal monitoring in neurocritical care

INTRODUCTION

Cerebral microdialysis is an established research tool that is used by an increasing number of neurocritical care units as a component of bedside multimodality monitoring. Body fluid biomarkers are an emerging tool for the assessment of brain injury. The correct interpretation of body fluid biomarker levels depends on the degree of recovery, i.e. relative recovery and the accuracy of the analytical technique.

METHODS

In vitro recovery experiments were performed on 100mL volumes of cerebrospinal fluid and solutions of S100B, glucose, lactate and pyruvate comparing relative recoveries using commercially available 20 kDa (CMA70) and 100 kDa (CMA71) microdialysis catheters. We also compared the CMA 600 microdialysis analyzer with a YSI 2003 STAT Plus analyzer for glucose and lactate to determine its reliability.

RESULTS

Significantly, we demonstrate the improved recovery of the protein S100B using a larger molecular weight (MW) cut-off catheter (20 kDa range: 0.1-9%; 100 kDa range: 1.7-18.3%) while maintaining comparable performance for the conventional markers glucose, lactate and pyruvate. Additionally we found that the CMA 600 analyzer may be prone to overestimation of lactate readings at higher concentration with implications for clinical decision-making.

CONCLUSION

Our data demonstrates that the 100 kDa MW cut-off catheter allows for the improved recovery of macromolecules in cerebral microdialysis research while maintaining the value of existing MD data for routine clinical use.

Investigation ofin vivomeasurement of cerebral cytochrome-c-oxidase redox changes using near-infrared spectroscopy in patients with orthostatic hypotension

We have previously used a continuous four-wavelength near-infrared spectrometer to measure changes in the cerebral concentrations of oxy-haemoglobin (Delta[HbO(2)] and deoxy-haemoglobin (Delta[HHb]) during head-up tilt in patients with primary autonomic failure. The measured changes in light attenuation also allow calculation of changes in the concentration of oxidized cytochrome-c-oxidase (Delta[(ox)CCO]), and this paper analyses the Delta[(ox)CCO] during the severe episodes of orthostatic hypotension produced by this experimental protocol. We studied 12 patients during a passive change in position from supine to a 60 degrees head-up tilt. The challenge caused a reduction in mean blood pressure of 59.93 (+/-26.12) mmHg (Mean (+/-SD), p < 0.0001), which was associated with a reduction in the total concentration of haemoglobin (Delta[HbT] = Delta[HbO(2)] + Delta[HHb]) of 5.02 (+/-3.81) microM (p < 0.0001) and a reduction in the haemoglobin difference concentration (Delta[Hb(diff)] = Delta[HbO(2)] - Delta[HHb]) of 14.4 (+/-6.73) microM (p < 0.0001). We observed a wide range of responses in Delta[(ox)CCO]. Six patients demonstrated a drop in Delta[(ox)CCO] (0.17 +/- 0.15 microM); four patients demonstrated no change (0.01 +/- 0.12 microM) and two patients showed an increase in Delta[(ox)CCO] (0.21 +/- 0.01 microM). Investigation of the association between the changes in concentrations of haemoglobin species and the Delta[(ox)CCO] for each patient show a range of relationships. This suggests that a simple mechanism for crosstalk, which might produce artefactual changes in [(ox)CCO], is not present between the haemoglobin and the (ox)CCO NIRS signals. Further investigation is required to determine the clinical significance of the changes in [(ox)CCO].

Spontaneous bilobar subcapsular hematoma of the liver while undergoing anticoagulation therapy: our experience and review of the literature

We report on a case of bilateral subcapsular hematoma of the liver, occurring during treatment with warfarin. A 64-year-old woman was put on long-term warfarin therapy. After a bout of severe right hypochondriac pain, computed tomography (CT) scan showed subcapsular hematoma of the liver. Subsequent CT scan, conservative policy only, showed regression of the hematoma. The patient was discharged from the hospital on the 23rd day. We conclude that a nonruptured spontaneous liver hematoma should not be surgically removed. A conservative management with close observation is the mainstay therapy. A switch from warfarin therapy to another anticoagulation therapy is strongly suggested.

Intra-operative specimen analysis using faxitron microradiography for excision of mammographically suspicious, non-palpable breast lesions

Recent advances in digital imaging have made Faxitron microradiography an attractive alternative to intra-operative conventional specimen radiography (CSR) for the excision of wire-localized breast lesions. Faxitron specimen analysis time, usefulness of digital image manipulation and re-excision rates were evaluated in comparison to CSR in 299 consecutive wire-localized excisions for mammographically suspicious non-palpable breast lesions (172 procedures with Faxitron, 127 with CSR) in a non-randomized study. The corresponding mean operation times were 34.7 vs. 42.7 min and the respective re-excision rates were 19.8% vs. 31.5% (no significant difference on chi analysis P < 0.1). Faxitron digital image manipulation led to cavity biopsies in 50% (60/121) of the cancer excisions. In 19 of these (16%), histological excision margins were converted from incomplete to complete. The shorter Faxitron mean operating time enables an additional wire-localized operation per theatre list. Digital imaging guides the surgeon for additional cavity biopsies, resulting in re-excision rates as good as CSR.