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Ramachandran A.,University of Kansas Medical Center | Ramachandran A.,The Wellcome Trust Research Laboratory | Mcgill M.R.,University of Kansas Medical Center | Xie Y.,University of Kansas Medical Center | And 3 more authors.
Hepatology | Year: 2013

Acetaminophen (APAP) overdose is a major cause of hepatotoxicity and acute liver failure in the U.S., but the pathophysiology is incompletely understood. Despite evidence for apoptotic signaling, hepatic cell death after APAP is generally considered necrotic in mice and in humans. Recent findings suggest that the receptor interacting protein kinase 3 (RIP3) acts as a switch from apoptosis to necrosis (programmed necrosis). Thus, the aim of the current investigation was to determine if RIP3 is involved in APAP-induced liver cell death. APAP (200-300 mg/kg) caused glutathione depletion and protein adduct formation, oxidant stress, mitochondrial release of apoptosis inducing factor, and nuclear DNA fragmentation resulting in centrilobular necrosis in C57Bl/6J mice. Inhibiting RIP3 protein induction with antisense morpholinos in wild-type animals or using RIP3-deficient mice had no effect on protein adduct formation but attenuated all other parameters, including necrotic cell death, at 6 hours after APAP. In addition, cultured hepatocytes from RIP3-deficient mice showed reduced injury compared to wild-type cells after 24 hours. Interestingly, APAP-induced mitochondrial translocation of dynamin-related protein 1 (Drp1), the initiator of mitochondrial fission, was inhibited by reduced RIP3 protein expression and the Drp1 inhibitor MDIVI reduced APAP-induced cell death at 24 hours. All of these protective effects were lost after 24 hours in vivo or 48 hours in vitro. Conclusion: RIP3 is an early mediator of APAP hepatotoxicity, involving modulation of mitochondrial dysfunction and oxidant stress. Controlling RIP3 expression could be a promising new approach to reduce APAP-induced liver injury, but requires complementary strategies to control mitochondrial dysfunction for long-term protection. © 2013 by the American Association for the Study of Liver Diseases. Source


Farrar J.,University of Oxford | Farrar J.,South East Asia Infectious Disease Clinical Research Network | Hotez P.J.,The Texas Institute | Junghanss T.,University of Heidelberg | And 3 more authors.
Manson's Tropical Diseases: Twenty-Third Edition | Year: 2013

2014 BMA Medical Book Awards Highly Commended in Public Health category! From the difficult to diagnose to the difficult to treat, Manson's Tropical Diseases prepares you to effectively handle whatever your patients may have contracted. Featuring an internationally recognized editorial team, global contributors, and expert authors, this revised and updated medical reference book provides you with the latest coverage on parasitic and infectious diseases from around the world. © 2015 Elsevier Ltd. All rights reserved. Source


Ramachandran A.,University of Kansas Medical Center | Ramachandran A.,The Wellcome Trust Research Laboratory | Lebofsky M.,University of Kansas Medical Center | Yan H.-M.,University of Kansas Medical Center | And 2 more authors.
Archives of Toxicology | Year: 2015

Chronic hepatitis C virus (HCV) infection predisposes patients to develop liver failure after acetaminophen (APAP) overdose. Mechanisms involved in this were explored using transgenic mice expressing the HCV structural proteins core, E1 and E2. Treatment of C57BL/6J mice with 200 mg/kg body weight APAP resulted in significant liver injury at 6 h as indicated by elevated ALT levels, focal centrilobular necrosis and nuclear DNA fragmentation. HCV transgenic mice showed a variable response, with approximately half the animals showing exacerbation of all parameters of liver injury, while the other half was protected. HCV transgenic mice with higher liver injury had lower liver glutathione levels, elevated mitochondrial oxidative stress and enhanced release of apoptosis-inducing factor (AIF) from the mitochondria. This was accompanied by induction of a higher ER stress response and induction of autophagy. Transgenic animals showing protection against liver injury had a robust recovery of liver glutathione content at 6 h when compared to wild-type animals, accompanied by reduction in mitochondrial oxidative stress and AIF release. This was accompanied by an elevation in glutathione S-transferase mRNA levels and activity, which suggests that an efficient clearance of the reactive intermediate may contribute to the protection against APAP hepatotoxicity in these mice. These results demonstrate that while HCV infection could exacerbate APAP-induced liver injury due to induction and amplification of mitochondrial oxidant stress, it could also protect against injury by activation of APAP scavenging mechanisms. © 2015, Springer-Verlag Berlin Heidelberg. Source


Grassly N.C.,Imperial College London | Grassly N.C.,The Wellcome Trust Research Laboratory | Kang G.,The Wellcome Trust Research Laboratory | Kampmann B.,Imperial College London | Kampmann B.,University of Cambridge
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2015

The reason for holding a meeting to discuss biological challenges to vaccines is simple: not all vaccines work equally well in all settings. This special issue reviews the performance of vaccines in challenging environments, summarizes current thinking on the reasons why vaccines underperform and considers what approaches are necessary to understand the heterogeneity in responses and to improve vaccine immunogenicity and efficacy. © 2015 The Author(s) Published by the Royal Society. All rights reserved. Source


Selvan B.,Christian Medical College | Ramachandran A.,The Wellcome Trust Research Laboratory | Korula A.,Christian Medical College | Amirtharaj G.J.,The Wellcome Trust Research Laboratory | And 5 more authors.
International Journal of Surgery | Year: 2012

Background: Investigations of molecular mechanisms behind the progression of neoplastic changes in the esophagus have uncovered the role of the COX & 5-Lox pathways. Human squamous esophageal mucosa produces relatively large amounts of eicosanoids in the presence of inflammation. Laboratory and epidemiological data suggest that aspirin and non-steroidal anti-inflammatory drugs may be chemo preventive through their inhibitory effect on COX25, 10. Cell culture studies have shown that the members of the mitogen activated protein (MAP) kinase family plays an important role in the development of bile acid-induced carcinogenesis. Differences in MAPK pathways activated by bile exposure were also noted in esophageal squamous cell lines and biopsies from patients with GERD. The protective role of aspirin and its molecular mechanism is not well understood. Aims: 1.The effect of duodenal reflux on esophageal mucosa.2.The role of aspirin in preventing duodenal reflux induced esophageal mucosa changes.3.If it is proven to be preventive, the mechanism of its action. A duodenal reflux rat animal model was used by an end- to-side esophago duodenostomy. Methods: Total of 56 rats was included. 3 were "Naive control" animals which did not undergo the surgical procedure. The remaining animals were divided into two groups: Surgery alone (experimental) and Surgery + aspirin [therapy group], esophagoduodenostomy. At 40 weeks, the rats were euthanized and appropriate esophageal samples were analysed for histopathology and p38 & ERK MAP kinases, VEGF, protease activity and caspase 3 activities. Results: The presence of gross mucosal nodularity was seen in 21 and 10 rats of the experimental and therapy group respectively (p = 0.03; Table 1). Reflux-associated changes such as basal cell hyperplasia were more common in the experimental group, however this association did not reach statistical significance (p = 0.15; Table 1). Epithelial hyperplasia was seen more in the experimental group, which was prevented by aspirin [. p < 0.01]. Papillomatosis, as shown in Fig. 4 was more common in the experimental group (p = 0.02). Activation of p38 & ERK MAP kinases was prevented in aspirin group (p < 0.05, CI -1.796--0.014). Examination of protease activity by zymographic analysis of the esophageal samples revealed a number of gelatinolytic bands in 50% rats of the experimental group, not observed in the therapy group. No significant changes were seen in Caspase 3 [Normal areas -99.74 & nodular areas - 100.34 percent of controls] or VEGF [mean 0.64, sd ± 0.76 Vs 0.69 ± 0.96] activity. Conclusions: Our data demonstrated that low dose aspirin reduced the incidence of duodenoesophageal reflux induced histological changes in the esophagus by preventing activation of proliferative & anti-apoptotic MAP kinases such as p38 & ER as well as protease activity. Though Barretts' changes and adenocarcinoma have not developed, it could explain the role of duodenoesophageal reflux in the development of different histological but potential premalignant lesions and molecular level changes which are prevented by low dose aspirin. © 2011 Surgical Associates Ltd. Source

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