A Case Report of Whitmore's Disease: A True Masquerader.

Melioidosis is an uncommon bacterial infection that is endemic to countries like Southeast Asia and Northern Australia but less common in temperate zones than when seen in returned travelers. This disease can affect almost every organ, with the lung being the most common organ to be involved. Here, we present a 21-year-old diabetic male who came with complaints of fever, nonproductive cough, and sore throat with grade III-IV shortness of breath. Laboratory investigations revealed hypokalemia and isolates of Burkholderia pseudomallei on blood culture and sensitivity. High-resolution computed tomography (HRCT) of the chest showed widespread, variable-sized nodules with central cavitations diffusely scattered in bilateral lungs.

Epilepsy in a mouse model of GNB1 encephalopathy arises from altered potassium (GIRK) channel signaling and is alleviated by a GIRK inhibitor.

De novo mutations in GNB1, encoding the Gß1 subunit of G proteins, cause a neurodevelopmental disorder with global developmental delay and epilepsy, GNB1 encephalopathy. Here, we show that mice carrying a pathogenic mutation, K78R, recapitulate aspects of the disorder, including developmental delay and generalized seizures. Cultured mutant cortical neurons also display aberrant bursting activity on multi-electrode arrays. Strikingly, the antiepileptic drug ethosuximide (ETX) restores normal neuronal network behavior in vitro and suppresses spike-and-wave discharges (SWD) in vivo. ETX is a known blocker of T-type voltage-gated Ca2+ channels and G protein-coupled potassium (GIRK) channels. Accordingly, we present evidence that K78R results in a gain-of-function (GoF) effect by increasing the activation of GIRK channels in cultured neurons and a heterologous model (Xenopus oocytes)-an effect we show can be potently inhibited by ETX. This work implicates a GoF mechanism for GIRK channels in epilepsy, identifies a new mechanism of action for ETX in preventing seizures, and establishes this mouse model as a pre-clinical tool for translational research with predicative value for GNB1 encephalopathy.

Phosphorylation on Syk Y342 is important for both ITAM and hemITAM signaling in platelets.

Immune cells express receptors bearing an immune tyrosine activation motif (ITAM) containing two YXXL motifs or hemITAMs containing only one YXXL motif. Phosphorylation of the ITAM/hemITAM is mediated by Src family kinases allowing for the binding and activation of spleen tyrosine kinase (Syk). It is believed that Syk must be phosphorylated on tyrosine residues for activation, and Tyr342, а conserved tyrosine in the interdomain B region, has been shown to be critical for regulating Syk in FcεR1-activated mast cells. Syk is a key mediator of signaling pathways downstream of several platelet pathways including the ITAM bearing glycoprotein VI (GPVI)/Fc receptor gamma chain collagen receptor and the hemITAM containing C-type lectin-like receptor-2 (CLEC-2). Since platelet activation is a crucial step in both hemostasis and thrombosis, we evaluated the importance of Syk Y342 in these processes by producing an Syk Y342F knock-in mouse. When using a CLEC-2 antibody as an agonist, reduced aggregation and secretion were observed in Syk Y342F mouse platelets when compared with control mouse platelets. Platelet reactivity was also reduced in response to the GPVI agonist collagen-related peptide. Signaling initiated by either GPVI or CLEC-2 was also greatly inhibited, including Syk Y519/520 phosphorylation. Hemostasis, as measured by tail bleeding time, was not altered in Syk Y342F mice, but thrombus formation in response to FeCl3 injury was prolonged in Syk Y342F mice. These data demonstrate that phosphorylation of Y342 on Syk following stimulation of either GPVI or CLEC-2 receptors is important for the ability of Syk to transduce a signal.

A selectivity filter mutation provides insights into gating regulation of a K+ channel.

G-protein coupled inwardly rectifying potassium (GIRK) channels are key players in inhibitory neurotransmission in heart and brain. We conducted molecular dynamics simulations to investigate the effect of a selectivity filter (SF) mutation, G154S, on GIRK2 structure and function. We observe mutation-induced loss of selectivity, changes in ion occupancy and altered filter geometry. Unexpectedly, we reveal aberrant SF dynamics in the mutant to be correlated with motions in the binding site of the channel activator Gßγ. This coupling is corroborated by electrophysiological experiments, revealing that GIRK2wt activation by Gßγ reduces the affinity of Ba2+ block. We further present a functional characterization of the human GIRK2G154S mutant validating our computational findings. This study identifies an allosteric connection between the SF and a crucial activator binding site. This allosteric gating mechanism may also apply to other potassium channels that are modulated by accessory proteins.

A revised mechanism of action of hyperaldosteronism-linked mutations in cytosolic domains of GIRK4 (KCNJ5).

G protein-gated, inwardly rectifying potassium channels (GIRK) mediate inhibitory transmission in brain and heart, and are present in the adrenal cortex. GIRK4 (KCNJ5) subunits are abundant in the heart and adrenal cortex. Multiple mutations of KCNJ5 cause primary aldosteronism (PA). Mutations in the pore region of GIRK4 cause loss of K+ selectivity, Na+ influx and depolarization of zona glomerulosa cells followed by hypersecretion of aldosterone. The concept of selectivity loss has been extended to mutations in cytosolic domains of GIRK4 channels, remote from the pore. We expressed aldosteronism-linked GIRK4R52H , GIRK4E246K and GIRK4G247R mutants in Xenopus oocytes. Whole-cell currents of heterotetrameric GIRK1/4R52H and GIRK1/4E246K channels were greatly reduced compared with GIRK1/4WT . Nevertheless, all heterotetrameric mutants retained full K+ selectivity and inward rectification. When expressed as homotetramers, only GIRK4WT , but none of the mutants, produced whole-cell currents. Confocal imaging, single-channel and Förster Resonance Energy Transfer (FRET) analyses showed: (1) reduction of membrane abundance of all mutated channels, especially as homotetramers, (2) impaired interaction with Gßγ subunits, and (3) reduced open probability of GIRK1/4R52H . VU0529331, a GIRK4 opener, activated homotetrameric GIRK4G247R channels, but not GIRK4R52H or GIRK4E246K . In the human adrenocortical carcinoma cell line (HAC15), VU0529331 and overexpression of heterotetrameric GIRK1/4WT , but not overexpression of GIRK1/4 mutants, reduced aldosterone secretion. Our results suggest that, contrary to pore mutants of GIRK4, non-pore mutants R52H and E246K mutants are loss-of-function rather than gain-of-function/selectivity-loss mutants. Hence, GIRK4 openers may be a potential course of treatment for patients with cytosolic N- and C-terminal mutations. KEY POINTS: Mutations in GIRK4 (KCNJ5) G protein-gated channels cause primary aldosteronism, a major cause of secondary hypertension. The primary mechanism is believed to be loss of K+ selectivity. R52H and E246K, aldosteronism-causing mutations in cytosolic N- and C- termini of GIRK4, were reported to cause loss of K+ selectivity. We show that R52H, E246K and G247R mutations render homotetrameric GIRK channels non-functional. In heterotetrameric context with GIRK1, these mutations impair membrane expression, interaction with Gßγ and open probability, but do not alter K+ selectivity or inward rectification. In the human aldosterone-secreting cell line, a GIRK4 opener and overexpression of heterotetrameric GIRK1/4WT , but not overexpression of GIRK1/4 mutants, reduced aldosterone secretion. Aldosteronism-causing mutations in the cytosolic domain of GIRK4 are loss-of-function mutations rather than gain-of-function, selectivity-loss mutations. Deciphering of exact biophysical mechanism that impairs the channel is crucial for setting the course of treatment.

Encephalopathy-causing mutations in Gß1 (GNB1) alter regulation of neuronal GIRK channels.

Mutations in the GNB1 gene, encoding the Gß1 subunit of heterotrimeric G proteins, cause GNB1 Encephalopathy. Patients experience seizures, pointing to abnormal activity of ion channels or neurotransmitter receptors. We studied three Gß1 mutations (K78R, I80N and I80T) using computational and functional approaches. In heterologous expression models, these mutations did not alter the coupling between G protein-coupled receptors to Gi/o, or the Gßγ regulation of the neuronal voltage-gated Ca2+ channel CaV2.2. However, the mutations profoundly affected the Gßγ regulation of the G protein-gated inwardly rectifying potassium channels (GIRK, or Kir3). Changes were observed in Gß1 protein expression levels, Gßγ binding to cytosolic segments of GIRK subunits, and in Gßγ function, and included gain-of-function for K78R or loss-of-function for I80T/N, which were GIRK subunit-specific. Our findings offer new insights into subunit-dependent gating of GIRKs by Gßγ, and indicate diverse etiology of GNB1 Encephalopathy cases, bearing a potential for personalized treatment.

Driving digital transformation of comprehensive primary health services at scale in India: an enterprise architecture framework.

In its commitment towards Sustainable Development Goals, India envisages comprehensive primary health services as a key pillar in achieving universal health coverage. Embedded in siloed vertical programmes, their lack of interoperability and standardisation limits sustainability and hence their benefits have not been realised yet. We propose an enterprise architecture framework that overcomes these challenges and outline a robust futuristic digital health infrastructure for delivery of efficient and effective comprehensive primary healthcare. Core principles of an enterprise platform architecture covering four platform levers to facilitate seamless service delivery, monitor programmatic performance and facilitate research in the context of primary healthcare are listed. A federated architecture supports the custom needs of states and health programmes through standardisation and decentralisation techniques. Interoperability design principles enable integration between disparate information technology systems to ensure continuum of care across referral pathways. A responsive data architecture meets high volume and quality requirements of data accessibility in compliance with regulatory requirements. Security and privacy by design underscore the importance of building trust through role-based access, strong user authentication mechanisms, robust data management practices and consent. The proposed framework will empower programme managers with a ready reference toolkit for designing, implementing and evaluating primary care platforms for large-scale deployment. In the context of health and wellness centres, building a responsive, resilient and reliable enterprise architecture would be a fundamental path towards strengthening health systems leveraging digital health interventions. An enterprise architecture for primary care is the foundational building block for an efficient national digital health ecosystem. As citizens take ownership of their health, futuristic digital infrastructure at the primary care level will determine the health-seeking behaviour and utilisation trajectory of the nation.

Phosphorylation of protein kinase Cδ Tyr311 positively regulates thromboxane generation in platelets.

Platelets are key mediators of physiological hemostasis and pathological thrombosis, whose function must be carefully balanced by signaling downstream of receptors such as protease-activated receptor (PAR)4. Protein kinase C (PKC) is known to regulate various aspects of platelet function. For instance, PKCδ is known to regulate dense granule secretion, which is important for platelet activation. However, the mechanism by which PKCδ regulates this process as well as other facets of platelet activity is unknown. We speculated that the way PKCδ regulates platelet function may be because of the phosphorylation of tyrosine residues on PKCδ. We investigated phosphorylation of PKCδ following glycoprotein VI-mediated and PAR4-mediated platelet activation and found that Y311 is selectively phosphorylated when PAR4 is activated in human platelets. Therefore, we generated PKCδ Y311F knock-in mice, which are viable and have no gross abnormalities. However, PKCδY311F mice have significantly enhanced tail-bleeding times compared with WT littermate controls, which means hemostasis is interrupted. Furthermore, PKCδY311F mice exhibit longer time to carotid artery occlusion compared with WT control using a ferric chloride in vivo thrombosis model, indicating that the phosphorylation of PKCδ Y311 is prothrombotic. Washed platelets from PKCδY311F mice have reduced reactivity after stimulation with a PAR-4 agonist indicating its importance in platelet signaling. The phenotype observed in Y311F mouse platelets is because of reduced thromboxane generation, as an inhibitor of thromboxane generation equalizes the PKCδY311F platelet response to that of WT. Therefore, phosphorylation of PKCδ on Y311 is important for regulation of platelet function and specifically thromboxane generation, which reinforces platelet activation.

Utilization of extracorporeal life support for diffuse alveolar damage and diffuse alveolar hemorrhage: A systematic review.

Modern extracorporeal life-support (ECLS) technology has been successfully utilized to treat patients with diffuse alveolar damage (DAD) and diffuse alveolar hemorrhage (DAH); however, reports in the literature remain scarce. We sought to pool existing evidence to better characterize ECLS use in these patients. An electronic search was conducted to identify all studies in the English literature reporting the use of ECLS for DAD/DAH. Thirty-two articles consisting of 38 patients were selected, and patient-level data were extracted and pooled for analysis. Median patient age was 36 [IQR: 27, 48] years, and the majority (63.2%) were female. Most common etiological factors included granulomatosis with polyangiitis (8/38, 21.1%), systemic lupus erythematosus (8/38, 21.1%), Goodpasture's syndrome (4/38, 10.5%), and microscopic polyangiitis (4/38, 10.5%). Immunologic markers included anti-neutrophil cytoplasmic antibody (ANCA) in 15/38 (39.5%), anti-nuclear antibody (ANA) in 6/38 (15.8%), and anti-glomerular basement membrane (anti-GBM) antibodies in 4/38 (10.5%). DAH was present in 32/38 (84.2%) of cases and DAD without evidence of DAH was present in 6/38 (15.8%) of cases. ECLS strategies included extracorporeal membrane oxygenation of veno-venous type (VV-ECMO) in 28/38 (73.7%), veno-arterial type (VA-ECMO) in 5/38 (13.2%), and one case of right ventricular assist device with oxygenator (RVAD-ECMO). Heparin was utilized in 18/38 (47.4%) of cases with no difference in use between DAH versus no DAH (P = .46) or VA- versus VV-ECLS (P = 1). Median duration of ECLS was 10 [5, 14] days. Pre- versus post-ECLS comparison of blood gases showed improvement in median PaO2 (49 [45, 59] mm Hg vs. 80 [70, 99] mm Hg, P < .001), PaO2:FiO2 ratio (48.2 [41.4, 54.8] vs. 182.0 [149.4, 212.2], P < .01), and pulse oximetry values (76% [72, 80] vs. 96% [94, 97], P = .086). Overall, 94.7% (36/38) of patients survived to decannulation while 30-day mortality was 10.5% (4/38) with no differences between VA- and VV-ECMO (P = 1 and P = .94, respectively). DAD/DAH occurs in a younger, predominantly female population, and tends to be associated with systemic autoimmune processes. ECLS, independent of its type, appears to result in favorable short-term survival.

Emerging drugs for small cell lung cancer: a focused review on immune checkpoint inhibitors.

INTRODUCTION: Small cell lung cancer (SCLC) is an aggressive malignancy that accounts for 15% of all lung cancers. It is characterized by initial responsiveness to therapy followed by rapid disease progression that is relatively resistant to further treatment. Recently, the addition of an immune checkpoint inhibitor (ICI) to chemotherapy has improved survival in patients with advanced disease, the first advance in systemic therapy in SCLC in over 30 years. AREAS COVERED: In this review, we present an overview of SCLC with a focus on the scope of the problem and standard treatment, followed by a critical assessment of scientific rationale for immunotherapy in SCLC and the clinical trials that have been performed with ICIs in SCLC. Finally, we address ongoing hurdles for the development of ICIs in SCLC and potential avenues for further study. EXPERT OPINION: Despite solid biological rationale, the results of clinical trials of ICIs in SCLC have yielded modest benefits. A small subset of patients does achieve long-term benefit, but further development of ICIs in SCLC will depend on the identification of predictive biomarkers and the design of combination regimens that take advantage of the molecular alterations that drive the immune-avoidance mechanisms and survival of SCLC cells.

Cyclin-dependent kinase inhibitors for the treatment of lung cancer.

INTRODUCTION: Cyclin-dependent kinases (CDKs) are critical regulators of cell cycle progression in both normal and malignant cells, functioning through complex molecular interactions. Deregulation of CDK-dependent pathways is commonly found in both non-small cell and small cell lung cancer, and these derangements suggest vulnerabilities that can be exploited for clinical benefit. AREAS COVERED: In this review, the authors present an overview of the biology of CDKs in normal and malignant cells, with a focus on lung cancer, followed by an assessment of preclinical work that has demonstrated the vital role of CDKs in lung cancer development and progression, and the activity of CDK inhibitors in a variety of lung cancer models. Finally, the experience with clinical trials of CDK inhibitors in lung cancer is discussed along with the current status of these agents in cancer therapy. EXPERT OPINION: Despite strong biological rationale and promising preclinical studies, the results of clinical trials of CDK inhibitors in lung cancer have thus far been disappointing. Further clinical development of CDK inhibitors in lung cancer will depend on the identification of predictive biomarkers and the design of combination regimens that take advantage of the unique molecular alterations that drive lung cancer growth and survival.

Real-world comparison of immune checkpoint inhibitors in non-small cell lung cancer following platinum-based chemotherapy.

PURPOSE: Immunotherapy is a relatively new treatment modality for advanced non-small cell lung cancer following platinum-based chemotherapy. Nivolumab, pembrolizumab, and atezolizumab demonstrated superior outcomes and improved tolerability compared to standard treatment in randomized controlled trials; however, these studies vary significantly in inclusion criteria and study design. To our knowledge, the efficacy and safety of nivolumab and atezolizumab following platinum-based chemotherapy have not been directly compared to one another in a real-world clinic setting. METHODS: We retrospectively compared immunotherapy response rates and toxicity in patients with stage IV or recurrent non-small cell lung cancer following progression during or after platinum-based chemotherapy. RESULTS: Among 124 eligible patients, the objective response rate was 14.8% in the nivolumab group (n = 81) vs. 13.9% in the atezolizumab group (n = 43) (p = 0.897). Median overall survival was 8.4 months with nivolumab (95% confidence interval (CI), 6.3 to 11.2) vs. 6.5 months with atezolizumab (95% CI, 4.7 to not reached). Median progression free survival was 2.2 months (95% CI, 1.7 to 2.8) and 2.0 months (95% CI, 1.8 to 2.7) in the nivolumab and atezolizumab groups, respectively. Treatment-related adverse events occurred in 70.4% of patients in the nivolumab group and 65.1% in the atezolizumab group. CONCLUSIONS: There was no statistically significant difference in efficacy outcomes in patients with non-small cell lung cancer who received atezolizumab or nivolumab after progression during or after platinum-based chemotherapy. Response rates in this study were numerically lower than response rates observed in the landmark randomized controlled trials leading to approval of immunotherapy in this setting. Rates of treatment-related adverse events were similar between groups.

The protein tyrosine phosphatase PTPN7 is a negative regulator of ERK activation and thromboxane generation in platelets.

Protein tyrosine phosphatase nonreceptor type 7 (PTPN7), also called hematopoietic protein tyrosine phosphatase, controls extracellular signal-regulated protein kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase in T lymphocytes. Because ERK1/2 plays an important role in regulating thromboxane A2 (TXA2) generation in platelets, we investigated the function of PTPN7 in these cells. Using immunoblot analysis, we detected PTPN7 in both human and mouse platelets but not in PTPN7-null mice. PTPN7 KO mouse platelets exhibited increased platelet functional responses, including aggregation, dense granule secretion, and TXA2 generation, compared with platelets from WT littermates, upon stimulation with both G protein-coupled receptor (GPCR) and glycoprotein VI (GPVI) agonists. Using the GPCR agonist AYPGKF in the presence of the COX inhibitor indomethacin, we found that PTPN7 KO mouse platelets aggregated and secreted to the same extent as WT platelets, suggesting that elevated TXA2 is responsible for the potentiation of platelet functional responses in PTPN7-KO platelets. Phosphorylation of ERK1/2 was also elevated in PTPN7 KO platelets. Stimulation of platelets with the GPVI agonist collagen-related peptide along with the COX inhibitor indomethacin did not result in phosphorylation of ERK1/2, indicating that GPVI-mediated ERK phosphorylation occurs through TXA2 Although bleeding times did not significantly differ between PTPN7-null and WT mice, time to death was significantly faster in PTPN7-null mice than in WT mice in a pulmonary thromboembolism model. We conclude that PTPN7 regulates platelet functional responses downstream of GPCR agonists, but not GPVI agonists, through inhibition of ERK activation and thromboxane generation.

Concomitant vs staged orthotopic liver transplant after cardiac surgical procedures.

BACKGROUND: In patients who require orthotopic liver transplant (OLT), cardiac surgery may be needed to optimize preoperative cardiac status for OLT. The aim of this systematic review was to evaluate patient characteristics and outcomes of those undergoing staged versus concomitant cardiac procedures with OLT. METHODS: An electronic search was performed to identify all case reports and series, from which patient-level data was extracted regarding cardiac procedures associated with OLT. After assessment for inclusion and exclusion criteria, 26 articles were pooled for systematic review. RESULTS: Overall, 49 patients were included in the analysis, of whom 12 (24%) underwent staged procedures and 37 (76%) underwent concomitant procedures. The median age was lower in the staged group [staged: 51 (IQR, 43.8-59.2) years vs. concomitant: 60 (IQR, 55.0-64.0) years, p = .02]. Other baseline characteristics were comparable between the two groups. For staged procedures, the median time between heart procedures and OLT was 2 (IQR, 1.0-3.5) months. The most commonly reported cardiac procedures were coronary artery bypass graft (CABG) [staged: 4/12 (33.3%) vs. concomitant: 21/37 (56.8%), p = .28], aortic valve replacement (AVR) [staged: 3/12 (25.0%) vs. concomitant: 19/37 (51.2%), p = .21], and transcatheter aortic valve replacement (TAVR) [staged: 4/12 (33.3%) vs. concomitant: 0/37 (0%), p = .002]. Regarding outcomes, there was a significantly shorter post-OLT hospital stay for those who had staged procedures versus those who had concomitant procedures [staged: 8 (IQR, 5-13) days vs. concomitant: 17 (IQR, 14-24) days, p = .007]. However, both groups had similar in-hospital mortality rates [staged: 1/12 (8.3%) vs. concomitant: 4/37 (10.8%), p = 1.0]. Overall survival stratified between the two groups was comparable. CONCLUSIONS: Patients who underwent the staged approach had a shorter post-transplant hospital stay, but comparable survival with respect to those who underwent concomitant cardiac procedures and OLT.

Heparin-induced thrombocytopenia during extracorporeal life support: incidence, management and outcomes.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a severe antibody-mediated reaction leading to transient prothrombosis. However, its incidence in patients on extracorporeal life support (ECLS) is not well described. The aim of this systematic review was to report the incidence of HIT in patients on ECLS, as well as compare the characteristics and outcomes of HIT in patients undergoing veno-arterial extracorporeal membrane oxygenation (VA-ECMO) and veno-venous ECMO (VV-ECMO). METHODS: An electronic search was performed to identify all studies in the English literature examining outcomes of patients with HIT on ECLS. All identified articles were systematically assessed using specific inclusion and exclusion criteria. Random effects meta-analysis as well as univariate analysis was performed. RESULTS: Of 309 patients from six retrospective studies undergoing ECLS, 83% were suspected, and 17% were confirmed to have HIT. Due to the sparsity of relevant retrospective data regarding patients with confirmed HIT on ECLS, patient-based data was subsequently collected on 28 patients from case reports and case series. Out of these 28 patients, 53.6% and 46.4% of them underwent VA-ECMO and VV-ECMO, respectively. Patients on VA-ECMO had a lower median platelet count nadir (VA-ECMO: 26.0 vs. VV-ECMO: 45.0 per µL, P=0.012) and were more likely to experience arterial thromboembolism (VA-ECMO: 53.3% vs. VV-ECMO: 0.0%, P=0.007), though there was a trend towards decreased likelihood of experiencing ECLS circuit oxygenator thromboembolism (VA-ECMO: 0.0% vs. VV-ECMO: 30.8%, P=0.075) and thromboembolism necessitating ECLS device or circuit exchange (VA-ECMO: 13.3% vs. VV-ECMO 53.8%, P=0.060). Kaplan-Meier survival plots including time from ECLS initiation reveal no significant differences in survival in patients supported on VA-ECMO as compared to VV-ECMO (P=0.300). CONCLUSIONS: Patients who develop HIT on VA-ECMO are more likely to experience more severe thrombocytopenia and arterial thromboembolism than those on VV-ECMO. Further research in this area and development of standardized protocols for the monitoring, diagnosis and management of HIT in patients on ECLS support are warranted.

Correction: Immune Checkpoint Inhibitor-Associated Colitis and Hepatitis.

The original version of this Article contained an error in the spelling of colitis in the article title. It was incorrectly spelt as "colits". This has now been corrected in both the PDF and HTML versions of the Article.

Immune Checkpoint Inhibitor-Associated Colitis and Hepatitis.

Immune checkpoint inhibitors (ICPIs) are monoclonal antibodies that target downregulators of the anti-cancer immune response: cytotoxic T-lymphocyte antigen-4, programmed cell death protein-1, and its ligand PD-L1. ICPIs are now approved for the treatment of a wide array of malignancies, with rates of durable responses in the metastatic setting far exceeding what would be expected from conventional chemotherapy. ICPIs have also been associated with rare but serious immune-related adverse events due to over-activation of the immune system that can affect any organ, including the gastrointestinal tract and liver. As the use of ICPIs in oncology continues to increase, ICPI-associated colitis and hepatitis will be encountered frequently by gastroenterologists and hepatologists. This review will focus on the diagnosis and management of ICPI-associated colitis and hepatitis. We will also compare these ICPI-related toxicities with sporadic inflammatory bowel disease and autoimmune liver disease.

The Neuropeptide Orexin-A Inhibits the GABAA Receptor by PKC and Ca2+/CaMKII-Dependent Phosphorylation of Its ß1 Subunit.

Orexin-A and orexin-B (Ox-A, Ox-B) are neuropeptides produced by a small number of neurons that originate in the hypothalamus and project widely in the brain. Only discovered in 1998, the orexins are already known to regulate several behaviours. Most prominently, they help to stabilise the waking state, a role with demonstrated significance in the clinical management of narcolepsy and insomnia. Orexins bind to G-protein-coupled receptors (predominantly postsynaptic) of two subtypes, OX1R and OX2R. The primary effect of Ox-OXR binding is a direct depolarising influence mediated by cell membrane cation channels, but a wide variety of secondary effects, both pre- and postsynaptic, are also emerging. Given that inhibitory GABAergic neurons also influence orexin-regulated behaviours, crosstalk between the two systems is expected, but at the cellular level, little is known and possible mechanisms remain unidentified. Here, we have used an expression system approach to examine the feasibility, and nature, of possible postsynaptic crosstalk between Ox-A and the GABAA receptor (GABAAR), the brain's main inhibitory neuroreceptor. When HEK293 cells transfected with OX1R and the α1, ß1, and γ2S subunits of GABAAR were exposed to Ox-A, GABA-induced currents were inhibited, in a calcium-dependent manner. This inhibition was associated with increased phosphorylation of the ß1 subunit of GABAAR, and the inhibition could itself be attenuated by (1) kinase inhibitors (of protein kinase C and CaM kinase II) and (2) the mutation, to alanine, of serine 409 of the ß1 subunit, a site previously identified in phosphorylation-dependent regulation in other pathways. These results are the first to directly support the feasibility of postsynaptic crosstalk between Ox-A and GABAAR, indicating a process in which Ox-A could promote phosphorylation of the ß1 subunit, reducing the GABA-induced, hyperpolarising current. In this model, Ox-A/GABAAR crosstalk would cause the depolarising influence of Ox-A to be boosted, a type of positive feedback that could, for example, facilitate the ability to abruptly awake.

The role of ß-elimination for the clinical activity of hypomethylating agents and cyclophosphamide analogues.

A beta-elimination reaction generally involves the cleavage of a sigma (σ) bond at the position beta (ß) to a pair of electrons that departs a molecule via a nucleophilic leaving group, subsequently leading to the formation of a new pi (π) bond. We describe the importance of ß-elimination reactions in the mechanisms of action of two classes of chemotherapeutic agents. First, we evaluate the chemical steps resulting in formation of 5-methyl-cytosine and its disassociation from DNA methytransferase (DNMT) by ß-elimination reaction. When carbon 5 (C5) of cytosine is substituted with a nitrogen atom (N) in 5-aza-cytosine analogues, the critical ß-elimination reaction cannot proceed, which results in the permanent attachment of 5-aza-cytosine to DNMT. The net outcome is entrapment of the DNMT by 5-aza-cytosine analogues and its eventual degradation, leading to DNA hypomethylation. Second, we analyze the critical role of ß-elimination reaction in the activation of cyclophosphamide and ifosfamide. The incapability of undergoing ß-elimination results in reduction of the cytotoxic activity of these agents. It appears that the conversion of aldehyde group, in aldophosphamide metabolites of cyclophosphamide and ifosfamide, to carboxyl group by aldehyde dehydrogenase makes the protons on the carbon atom attached to carboxyl group not acidic enough that can be removed under physiologic conditions via initiation of the critical ß-elimination reaction. This ultimately culminates in selective cytotoxic effect of these agents against lymphocytes but not hematopoietic and other stem cells with high aldehyde dehydrogenase content.