Novel means of monitoring hepatic damage

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A quantitative study of tau pathology in eleven cases of chronic traumatic encephalopathy

AIMS: To quantify tau pathology of chronic traumatic encephalopathy (CTE) and investigate influence of dot-like lesions (DL), brain region, co-morbidity, and sporting career length. METHODS: Densities of neurofibrillary tangles (NFT), astrocytic tangles (AT), DL, oligodendroglial inclusions (GI), neuropil threads (NT), vacuoles, neurons, and enlarged neurons (EN) were measured in tau-immunoreactive sections of upper cortical laminae of frontal and temporal lobe, hippocampus (HC), amygdala, and substantia nigra (SN) of eleven cases of CTE. RESULTS: DL were a consistent finding in CTE. Densities of NFT, NT and DL were greatest in sectors CA1 and CA2 of the HC. Densities of AT were lower than NFT, small numbers of GI were recorded in temporal lobe, and low densities of vacuoles and EN were consistently present. β-amyloid containing neuritic plaques (NP) also occurred at low density. Densities of NFT, NT, DL, and AT were greater in sulci than gyri while vacuole density was greater in gyri. Principal components analysis (PCA) suggested that sporting career length and densities of NFT in entorhinal cortex, NT in CA2 and SN, and vacuolation in the DG were significant sources of variation among cases. CONCLUSION: DL are frequent in CTE suggesting affinity with argyrophilic grain disease (AGD) and Parkinson's disease dementia (PD-Dem). Densities of AT in all regions and NT/DL in sectors CA2/4 were consistent features of CTE. The eleven cases are neuropathologically heterogeneous which may result from genetic diversity, and variation in anatomical pathways subjected to trauma. This article is protected by copyright. All rights reserved.

Pathology of the superior colliculus in chronic traumatic encephalopathy

PURPOSE: To investigate neuropathological changes in the superior colliculus in chronic traumatic encephalopathy. METHODS: The densities of the tau-immunoreactive neurofibrillary tangles, neuropil threads, dot-like grains, astrocytic tangles, and neuritic plaques, together with abnormally enlarged neurons, typical neurons, vacuolation, and frequency of contacts with blood vessels, were studied across the superior colliculus from pia mater to the periaqueductal gray in eight chronic traumatic encephalopathy and six control cases. RESULTS: Tau-immunoreactive pathology was absent in the superior colliculus of controls but present in varying degrees in all chronic traumatic encephalopathy cases, significant densities of tau-immunoreactive neurofibrillary tangles, NT, or dot-like grains being present in three cases. No significant differences in overall density of the tau-immunoreactive neurofibrillary tangles, neuropil threads, dot-like grains, enlarged neurons, vacuoles, or contacts with blood vessels were observed in control and chronic traumatic encephalopathy cases, but chronic traumatic encephalopathy cases had significantly lower mean densities of neurons. The distribution of surviving neurons across the superior colliculus suggested greater neuronal loss in intermediate and lower laminae in chronic traumatic encephalopathy. Changes in density of the tau-immunoreactive pathology across the laminae were variable, but in six chronic traumatic encephalopathy cases, densities of tau-immunoreactive neurofibrillary tangles, neuropil threads, or dot-like grains were significantly greater in intermediate and lower laminae. Pathological changes were not correlated with the distribution of blood vessels. CONCLUSIONS: The data suggest significant pathology affecting the superior colliculus in a proportion of chronic traumatic encephalopathy cases with a laminar distribution which could compromise motor function rather than sensory analysis.

Hepatic Responses of Juvenile Fundulus heteroclitus from Pollution-adapted and Nonadapted Populations Exposed to Elizabeth River Sediment Extract.

Atlantic killifish (Fundulus heteroclitus) inhabiting the Atlantic Wood Industries region of the Elizabeth River, Virginia, have passed polycyclic aromatic hydrocarbon (PAH) resistance to their offspring as evidenced by early life stage testing of developmental toxicity after exposure to specific PAHs. Our study focused on environmentally relevant PAH mixtures in the form of Elizabeth River sediment extract (ERSE). Juvenile (5 month) F1 progeny of pollution-adapted Atlantic Wood (AW) parents and of reference site (King's Creek [KC]) parents were exposed as embryos to ERSE. Liver alterations, including nonneoplastic lesions and microvesicular vacuolation, were observed in both populations. ERSE-exposed KC fish developed significantly more alterations than unexposed KC fish. Interestingly, unexposed AW killifish developed significantly more alterations than unexposed KC individuals, suggesting that AW juveniles are not fully protected from liver disease; rapid growth of juvenile fish may also be an accelerating factor for tumorigenesis. Because recent reports show hepatic tumor formation in adult AW fish, the differing responses from the 2 populations provided a way to determine whether embryo toxicity protection extends to juveniles. Future investigations will analyze older life stages of killifish to determine differences in responses related to chronic disease.

Investigating metabolomic biomarkers of hypoxic ischaemic encephalopathy

Background An early objective biomarker to predict the severity of hypoxic-ischaemic encephalopathy (HIE) and identify infants suitable for intervention remains elusive. This thesis aims to progress metabolomic markers of HIE through a pipeline of biomarker discovery and validation by employing a novel untargeted mass spectrometry metabolomic method. Methodology Term infants with perinatal asphyxia were recruited, all having umbilical cord blood (UCB) drawn and biobanked within three hours of birth. HIE was defined by Sarnat score at 24hours and continuous multichannel-EEG. Infant neurodevelopment was assessed at 36-42 months using the Bayley Scales of Infant and Toddler Development Ed. III (BSID-III). Untargeted metabolomic analysis of UCB was performed using direct injection FT-ICR mass spectrometry (DI FT-ICR MS). Putative metabolite annotations and lipid classes were assigned and pathway analysis was performed. Results Untargeted metabolomic analysis: Thirty enrolled infants were diagnosed with HIE, including 17 mild, 8 moderate, and 5 severe cases. Pathway analysis revealed that ΔHIE was associated with a 50% and 75% perturbation of tryptophan and pyrimidine metabolism respectively, alongside alterations in amino acid pathways. Significant metabolite alterations were detected from six putatively identified lipid classes including fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterol lipids and prenol lipids. Outcome prediction: Metabolite model scores significantly correlated with outcome R=0.429 (model A) and R=0.549 (model B) respectively. Model B demonstrates the potential to predict both severe outcome (AUROC of 0.915) and intact survival (AUROC of 0.800). The effect of haemolysis: On average 5% of polar and 1.5% of non-polar features were altered between paired haemolysed and clean samples. However unsupervised multivariate analysis concluded that the preanalytical variability introduced by haemolysis was negligible compared with the inherent biological inter-individual variability. Conclusion This research has employed untargeted metabolomics to identify potential early cord blood biomarkers of HIE and has performed the technical validation of previously proposed markers.

MicroRNA expression and function in neonatal hypoxic ischaemic encephalopathy

Hypoxic ischaemic encephalopathy (HIE) is a devastating neonatal condition which affects 2-3 per 1000 infants annually. The current gold standard of treatment - induced hypothermia, has the ability to reduce neonatal mortality and improve neonatal morbidity. However, to be effective it needs to be initiated within the therapeutic window which exists following initial insult until approximately 6 hours after birth. Current methods of assessment which are relied upon to identify infants with HIE are subjective and unreliable. To overcome this issue, an early and reliable biomarker of HIE severity must be identified. MicroRNA (miRNA) are a class of small non-coding RNA molecules which have potential as biomarkers of disease state and potential therapeutic targets. These tiny molecules can modulate gene expression by inhibiting translation of messenger RNA (mRNA) and as a result, can regulate protein synthesis. These miRNA are understood to be released into the circulation during cellular stress, where they are highly stable and relatively easy to quantify. Therefore, these miRNAs may be ideal candidates for biomarkers of HIE severity and may aid in directing the clinical management of these infants. By using both transcriptomic and proteomic approaches to analyse the expression of miRNAs and their potential targets in the umbilical cord blood, I have confirmed that infants with perinatal asphyxia and HIE have a significantly different UCB miRNA signature compared to UCB samples from healthy controls. Finally, I have identified and investigated 2 individual miRNAs; both of which show some potential as classifiers of HIE severity and predictors of long term outcome, particularly when coupled with their downstream targets. While this work will need to be validated and expanded in a new and larger cohort of infants, it suggests the potential of miRNA as biomarkers of neonatal pathological conditions such as HIE.

Seizure burden and neurodevelopmental outcome in neonates with hypoxic-ischemic encephalopathy.

Aim: To examine the relationship between electrographic seizures and long-term outcome in neonates with hypoxic-ischemic encephalopathy (HIE). Method: Full-term neonates with HIE born in Cork University Maternity Hospital from 2003 to 2006 (pre-hypothermia era) and 2009 to 2012 (hypothermia era) were included in this observational study. All had early continuous electroencephalography monitoring. All electrographic seizures were annotated. The total seizure burden and hourly seizure burden were calculated. Outcome (normal/abnormal) was assessed at 24 to 48 months in surviving neonates using either the Bayley Scales of Infant and Toddler Development, Third Edition or the Griffiths Mental Development Scales; a diagnosis of cerebral palsy or epilepsy was also considered an abnormal outcome. Results: Continuous electroencephalography was recorded for a median of 57.1 hours (interquartile range 33.5-80.5h) in 47 neonates (31 males, 16 females); 29 out of 47 (62%) had electrographic seizures and 25 out of 47 (53%) had an abnormal outcome. The presence of seizures per se was not associated with abnormal outcome (p=0.126); however, the odds of an abnormal outcome increased over ninefold (odds ratio [OR] 9.56; 95% confidence interval [95% CI] 2.43-37.67) if a neonate had a total seizure burden of more than 40 minutes (p=0.001), and eightfold (OR: 8.00; 95% CI: 2.06-31.07) if a neonate had a maximum hourly seizure burden of more than 13 minutes per hour (p=0.003). Controlling for electrographic HIE grade or treatment with hypothermia did not change the direction of the relationship between seizure burden and outcome. Interpretation: In HIE, a high electrographic seizure burden is significantly associated with abnormal outcome, independent of HIE severity or treatment with hypothermia.