Lipid peroxidation is a nonparenchymal cell event with reperfusion after prolonged liver ischemia

A proposed mechanism for irreversible ischemic liver damage has been peroxidation of membrane phospholipids by free radicals. However, the hepatocyte is laden with enzymes which are antioxidants and, therefore, ought to be relatively resistant to oxidative injury. To test the hypothesis that free radical damage from ischemia and reperfusion of the liver is a nonparenchymal cell process, we studied an in vivo model of ischemia. A point of transition from reversible to irreversible ischemia was defined at ≥60 min of total ischemia by serial measurements of ATP at control, end of ischemia, and end of reperfusion periods (n = 6 each). Nonparenchymal cells were separated out of 10 livers in each ischemic group using a Percoll gradient. Second derivative spectroscopy did not detect conjugated dienes in any hepatocellular fraction, total cellular, mitochondrial, or microsomal, but did in the nonparenchymal cell fractions of livers from the 60- and 90-min ischemia groups. This in vivo study shows that irreversible ischemia in the rat liver is associated with free radical lipid peroxidation, but that the nonparenchymal cells rather than hepatocytes are the focus of this injury. © 1990

An improved technique for isolated perfusion of rat livers and an evaluation of perfusates

We have modified the apparatus for isolated rat liver perfusion (IPRL) in order to be able to perform two perfusions simultaneously. In addition, we studied the quality and stability of livers by comparison of five different perfusates: Blood (Group A), Original Krebs Henseleit buffer (Group B), Krebs buffer with glucose (Group C) or bovine serum albumin (BSA) added, (Group D). In a last group (E) albumin, glucose, and taurocholic acid were added to Krebs. After 180 min of perfusion, livers perfused with solutions including 2% albumin (Group D, E) had a significantly higher release of hepatocellular and endothelial cell (purine nucleoside phosphorylase) enzymes and lower bile production as compared to Groups A, B, and C (P < 0.0001). Increasing levels of purine nucleoside phosphorylase (PNP), a reflection of damage to the microvascular endothelium preceded the increases in hepatocellular enzymes. Histologically, damages of sinusoidal endothelial cells and hepatocytes are appreciated moderate to severe in Groups D and E, slight to mild in Groups A and B, and not significant in Group C. These results suggest that BSA may have toxic effects to the perfused rat liver. These data also confirm that the IPRL modified for simultaneous perfusion of two livers is efficient, and that with this technique the rat liver can be optimally perfused for up to 3 hr with oxygenated Krebs Henseleit buffer without additives (Group B) and without blood. These two improvements should allow those performing studies with perfused rat livers to obtain data in a more efficient, accurate, and inexpensive fashion. © 1992

Inhibition of free radical generation and improved survival by protection of the hepatic microvascular endothelium by targeted erythrocytes in orthotopic rat liver transplantation

The capacity of specifically targeted erythrocytes to inhibit free radical—mediated injury to the endothelial cell after cold preservation, and improve liver function was studied in two experimental models: An isolated perfused rat liver (IPRL) system and syngeneic orthotopic rat liver transplantation. In the IPRL model, livers were preserved in University of Wisconsin solution for 24 h at 4°C. At the end of the preservation period, livers were flushed with lactated Ringer’s (control), immu- noerythrocytes (IES), or blank intact erythrocytes prior to warm reperfusion for 2 h using an assanguinous Krebs-Henseleit buffer. Production of superoxide (O2-) anion during warm reperfusion in the IES-treated liver was reduced by 65% as compared with controls (P<0.001) and by 74% (P<0.001) when compared with blank erythrocyte—treated livers. Endothelial cell preservation, as assessed by levels of purine nucleoside phos- phorylase (PNP), was much better in the IES-treated group (P<0.001) when compared with untreated livers. Hepatocellular preservation was markedly improved in the IES-treated livers. In the syngeneic liver transplantation model, livers were preserved in UW solution for 24 h at 4°C. Prior to implantation, livers were flushed with 5 ml of cold lactated Ringer’s or immunoerythrocytes. Survival after three weeks was 60% in the IES-treated group and 30% in the untreated group. Survival in the IES-treated group was not significantly different from a control (no preservation) group. IES-treated livers in both models demonstrated better endothelial cell integrity and ultimate liver function. IES treatment therefore appears to protect the hepatic microvascular endothelial cell from reperfusion injury and could prove to be an easy reproducible method of donor organ preparation after cold preservation. © 1990 by Williams & Wilkins

A preliminary audit of medical and aid provision in English Rugby union clubs:compliance with Regulation 9

BackgroundGoverning bodies are largely responsible for the monitoring and management of risks associated with a safe playing environment, yet adherence to regulations is currently unknown. The aim of this study was to investigate and evaluate the current status of medical personnel, facilities, and equipment in Rugby Union clubs at regional level in England.MethodsA nationwide cross-sectional survey of 242 registered clubs was undertaken, where clubs were surveyed online on their current medical personnel, facilities, and equipment provision, according to regulation 9 of the Rugby Football Union (RFU).ResultsOverall, 91 (45. 04%) surveys were returned from the successfully contacted recipients. Of the completed responses, only 23.61% (n = 17) were found to be compliant with regulations. Furthermore, 30.56% (n = 22) of clubs were unsure if their medical personnel had required qualifications; thus, compliance could not be determined. There was a significant correlation (p = −0.029, r = 0.295) between club level and numbers of practitioners. There was no significant correlation indicated between the number of practitioners/number of teams and number of practitioners/number of players. There were significant correlations found between club level and equipment score (p = 0.003, r = −0.410), club level and automated external defibrillator (AED) access (p = 0.002, r = −0.352) and practitioner level and AED access (p = 0.0001, r = 0.404). Follow-up, thematic analysis highlighted widespread club concern around funding/cost, awareness, availability of practitioners and AED training.ConclusionThe proportion of clubs not adhering overall compliance with Regulation 9 of the RFU is concerning for player welfare, and an overhaul, nationally, is required

A response to Rome: lessons from pre- and post-publication data-sharing in the C. elegans research community

<p>Abstract</p> <p>Background</p> <p>In recent years numerous studies have undertaken to measure the impact of patents, material transfer agreements, data-withholding and commercialization pressures on biomedical researchers. Of particular concern is the theory that such pressures may have negative effects on academic and other upstream researchers. In response to these concerns, commentators in some research communities have called for an increased level of access to, and sharing of, data and research materials. We have been studying how data and materials are shared in the community of researchers who use the nematode <it>Caenorhabditis elegans </it>(<it>C. elegans</it>) as a model organism for biological research. Specifically, we conducted a textual analysis of academic articles referencing <it>C. elegans</it>, reviewed <it>C. elegans </it>repository request lists, scanned patents that reference <it>C. elegans </it>and conducted a broad survey of <it>C. elegans </it>researchers. Of particular importance in our research was the role of the <it>C. elegans </it>Gene Knockout Consortium in the facilitation of sharing in this community.</p> <p>Results</p> <p>Our research suggests that a culture of sharing exists within the <it>C. elegans </it>research community. Furthermore, our research provides insight into how this sharing operates and the role of the culture that underpins it.</p> <p>Conclusions</p> <p>The greater scientific community is likely to benefit from understanding the factors that motivate <it>C. elegans </it>researchers to share. In this sense, our research is a 'response' to calls for a greater amount of sharing in other research communities, such as the mouse community, specifically, the call for increased investment and support of centralized resource sharing infrastructure, grant-based funding of data-sharing, clarity of third party recommendations regarding sharing, third party insistence of post-publication data sharing, a decrease in patenting and restrictive material transfer agreements, and increased attribution and reward.</p

A pilot survey of physical activity in men with an intellectual disability

People with intellectual disability are reported as a sedentary population with increased risks of poor health due to an inactive and sedentary lifestyle. As the benefits of physical activity are acknowledged, measuring physical activity accurately is important to help identify reasons for low and high physical activity in order to assist and maintain recommended levels for optimal health. This paper reports a pilot study undertaken to validate the use of a physical activity monitor (Sensewear Armband) and the International Physical Activity Questionnaire (IPAQ) as instruments for measuring and exploring physical activity of men with intellectual disability. The design was a one group descriptive study and data were collected over a 7 day period from 17 men. The Sensewear Armband enabled continuous and long-term measurement of 14 objective physical activity metrics. The IPAQ examined details of physical activity reported over the 7 days. Equivalent results were found in both instruments indicating a positive correlation between the Sensewear Armband and the IPAQ. The results show 50% have low activity levels and the national recommended physical activity levels been achieved at a very low active intensity. No sustainable high physical activity intensity levels were recorded. The results confirmed the Sensewear Armband and the IPAQ as a practical means of measuring and understanding physical activity levels of men with intellectual disability

Urinary retinol binding protein predicts renal outcome in systemic immunoglobulin light-chain (AL) amyloidosis

Summary: Renal risk stratification in systemic immunoglobulin light-chain (AL) amyloidosis is according to estimated glomerular filtration rate (eGFR) and urinary protein creatinine ratio (uPCR), the latter attributed to glomerular dysfunction, with proximal tubular dysfunction (PTD) little studied. Urinary retinol binding protein 4 (uRBP), a low molecular weight tubular protein and highly sensitive marker of PTD, was prospectively measured in 285 newly diagnosed, untreated patients with systemic AL amyloidosis between August 2017 to August 2018. At diagnosis, the uRBP/creatinine ratio (uRBPCR) correlated with serum creatinine (r = 0·618, P 30 ml/min/1.73 m2 [HR 4·11, (95% CI 1·45–11·65); P = 0·008] and those who failed to achieve a deep haematological response to chemotherapy within 3 months of diagnosis [HR 6·72, (95% CI 1·83–24·74); P = 0·004], and also predicted renal progression [HR 1·91, (95% CI 1·18–3·07); P = 0·008]. Elevated uRBPCR indicates PTD and predicts renal outcomes independently of eGFR, uPCR and clonal response in systemic AL amyloidosis. The role of uRBPCR as a novel prognostic biomarker merits further study, particularly in monoclonal gammopathies of renal significance

The Molecular Assembly of Amyloid Aβ Controls Its Neurotoxicity and Binding to Cellular Proteins

Accumulation of β-sheet-rich peptide (Aβ) is strongly associated with Alzheimer's disease, characterized by reduction in synapse density, structural alterations of dendritic spines, modification of synaptic protein expression, loss of long-term potentiation and neuronal cell death. Aβ species are potent neurotoxins, however the molecular mechanism responsible for Aβ toxicity is still unknown. Numerous mechanisms of toxicity were proposed, although there is no agreement about their relative importance in disease pathogenesis. Here, the toxicity of Aβ 1–40 and Aβ 1–42 monomers, oligomers or fibrils, was evaluated using the N2a cell line. A structure-function relationship between peptide aggregation state and toxic properties was established. Moreover, we demonstrated that Aβ toxic species cross the plasma membrane, accumulate in cells and bind to a variety of internal proteins, especially on the cytoskeleton and in the endoplasmatic reticulum (ER). Based on these data we suggest that numerous proteins act as Aβ receptors in N2a cells, triggering a multi factorial toxicity

Sensitive detection of Aβ protofibrils by proximity ligation - relevance for Alzheimer's disease

<p>Abstract</p> <p>Background</p> <p>Protein aggregation plays important roles in several neurodegenerative disorders. For instance, insoluble aggregates of phosphorylated tau and of Aβ peptides are cornerstones in the pathology of Alzheimer's disease. Soluble protein aggregates are therefore potential diagnostic and prognostic biomarkers for their cognate disorders. Detection of the aggregated species requires sensitive tools that efficiently discriminate them from monomers of the same proteins. Here we have established a proximity ligation assay (PLA) for specific and sensitive detection of Aβ protofibrils via simultaneous recognition of three identical determinants present in the aggregates. PLA is a versatile technology in which the requirement for multiple target recognitions is combined with the ability to translate signals from detected target molecules to amplifiable DNA strands, providing very high specificity and sensitivity.</p> <p>Results</p> <p>For specific detection of Aβ protofibrils we have used a monoclonal antibody, mAb158, selective for Aβ protofibrils in a modified PLA, where the same monoclonal antibody was used for the three classes of affinity reagents required in the assay. These reagents were used for detection of soluble Aβ aggregates in solid-phase reactions, allowing detection of just 0.1 pg/ml Aβ protofibrils, and with a dynamic range greater than six orders of magnitude. Compared to a sandwich ELISA setup of the same antibody the PLA increases the sensitivity of the Aβ protofibril detection by up to 25-fold. The assay was used to measure soluble Aβ aggregates in brain homogenates from mice transgenic for a human allele predisposing to Aβ aggregation.</p> <p>Conclusions</p> <p>The proximity ligation assay is a versatile analytical technology for proteins, which can provide highly sensitive and specific detection of Aβ aggregates - and by implication other protein aggregates of relevance in Alzheimer's disease and other neurodegenerative disorders.</p