α-SNAP Enhances SNARE Zippering by Stabilizing the SNARE Four-Helix Bundle

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Lu Ma, Yuhao Kang, Junyi Jiao, Aleksander A. Rebane, Hyo Keun Cha, Zhiqun Xi, Hong Qu, Yongli Zhang
Intracellular membrane fusion is mediated by dynamic assembly and disassembly of soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein (SNAP) receptors (SNAREs). α-SNAP guides NSF to disassemble SNARE complexes after membrane fusion. Recent experiments showed that α-SNAP also dramatically enhances SNARE assembly and membrane fusion. How α-SNAP is involved in these opposing activities is not known. Here, we examine the effect of α-SNAP on the stepwise assembly of the synaptic SNARE complex using optical tweezers. We found that α-SNAP destabilized the linker domain (LD) of the SNARE complex but stabilized its C-terminal domain (CTD) through a conformational selection mechanism. In contrast, α-SNAP minimally affected assembly of the SNARE N-terminal domain (NTD), indicating that α-SNAP barely bound the partially assembled trans-SNARE complex. Thus, α-SNAP recognizes the folded CTD for SNARE disassembly with NSF and subtly modulates membrane fusion by altering the stabilities of the SNARE CTD and LD.

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Teaser

Using a single-molecule approach, Ma et al. find that α-SNAP plays distinct roles in stepwise SNARE assembly: it destabilizes the SNARE linker domain, stabilizes the C-terminal domain, but hardly affects the N-terminal domain. The findings shed light on membrane fusion as well as α-SNAP’s opposing functions in SNARE assembly and disassembly.


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HDAC3 Is a Master Regulator of mTEC Development

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Yael Goldfarb, Noam Kadouri, Ben Levi, Asaf Sela, Yonatan Herzig, Ronald N. Cohen, Anthony N. Hollenberg, Jakub Abramson
The thymus provides a unique microenvironment enabling development and selection of T lymphocytes. Medullary thymic epithelial cells (mTECs) play a pivotal role in this process by facilitating negative selection of self-reactive thymocytes and the generation of Foxp3⁺ regulatory T cells. Although studies have highlighted the non-canonical nuclear factor κB (NF-κB) pathway as the key regulator of mTEC development, comprehensive understanding of the molecular pathways regulating this process still remains incomplete. Here, we demonstrate that the development of functionally competent mTECs is regulated by the histone deacetylase 3 (Hdac3). Although histone deacetylases are global transcriptional regulators, this effect is highly specific only to Hdac3, as neither Hdac1 nor Hdac2 inactivation caused mTEC ablation. Interestingly, Hdac3 induces an mTEC-specific transcriptional program independently of the previously recognized RANK-NFκB signaling pathway. Thus, our findings uncover yet another layer of complexity of TEC lineage divergence and highlight Hdac3 as a major and specific molecular switch crucial for mTEC differentiation.

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Teaser

Goldfarb et al. show that Hdac3 is essential for normal development and function of medullary thymic epithelial cells (mTECs) independently of non-canonical NFκB signaling. Their findings highlight Hdac3 as a master switch inducing the mTEC transcriptional program in immature TECs.


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The Mitochondrial Respiratory Chain Is Required for Organismal Adaptation to Hypoxia

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Robert B. Hamanaka, Samuel E. Weinberg, Colleen R. Reczek, Navdeep S. Chandel
Hypoxia-inducible factors (HIFs) are crucial for cellular and organismal adaptation to hypoxia. The mitochondrial respiratory chain is the largest consumer of oxygen in most mammalian cells; however, it is unknown whether the respiratory chain is necessary for in vivo activation of HIFs and organismal adaptation to hypoxia. HIF-1 activation in the epidermis has been shown to be a key regulator of the organismal response to hypoxic conditions, including renal production of erythropoietin (Epo). Therefore, we conditionally deleted expression of TFAM in mouse epidermal keratinocytes. TFAM is required for maintenance of the mitochondrial genome, and TFAM-null cells are respiratory deficient. TFAM loss in epidermal keratinocytes reduced epidermal levels of HIF-1α protein and diminished the hypoxic induction of HIF-dependent transcription in epidermis. Furthermore, epidermal TFAM deficiency impaired hypoxic induction of renal Epo expression. Our results demonstrate that the mitochondrial respiratory chain is essential for in vivo HIF activation and organismal adaptation to hypoxia.

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Teaser

Hamanaka et al. show that loss of mitochondrial respiratory activity in the mouse epidermis impairs hypoxic activation of HIF-1. Since epidermal HIF-1 promotes cutaneous vasodilation and blood flow during hypoxia and potentiates the hypoxic response in the internal organs, mice with loss of TFAM in the epidermis are unable to induce renal erythropoietin expression in response to hypoxia.


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The Biogenesis of Nascent Circular RNAs

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Yang Zhang, Wei Xue, Xiang Li, Jun Zhang, Siye Chen, Jia-Lin Zhang, Li Yang, Ling-Ling Chen
Steady-state circular RNAs (circRNAs) have been mapped to thousands of genomic loci in mammals. We studied circRNA processing using metabolic tagging of nascent RNAs with 4-thiouridine (4sU). Strikingly, the efficiency of circRNA processing from pre-mRNA is extremely low endogenously. Additional studies revealed that back-splicing outcomes correlate with fast RNA Polymerase II elongation rate and are tightly controlled by cis-elements in vivo. Additionally, prolonged 4sU labeling in cells shows that circRNAs are largely processed post-transcriptionally and that circRNAs are stable. Circular RNAs that are abundant at a steady-state level tend to accumulate. This is particularly true in cells, such as neurons, that have slow division rates. This study uncovers features of circRNA biogenesis by investigating the link between nascent circRNA processing and transcription.

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Teaser

Zhang et al. study the link between circRNA processing and transcription using 4sUDRB-seq. They find that circRNA production from pre-mRNA back-splicing is slow and largely occurs post-transcriptionally. The authors argue that circRNAs that are abundant at a steady-state level tend to be transcribed quickly and accumulate.


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BET Bromodomain Inhibition Releases the Mediator Complex from Select cis-Regulatory Elements

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Anand S. Bhagwat, Jae-Seok Roe, Beverly Y.L. Mok, Anja F. Hohmann, Junwei Shi, Christopher R. Vakoc
The bromodomain and extraterminal (BET) protein BRD4 can physically interact with the Mediator complex, but the relevance of this association to the therapeutic effects of BET inhibitors in cancer is unclear. Here, we show that BET inhibition causes a rapid release of Mediator from a subset of cis-regulatory elements in the genome of acute myeloid leukemia (AML) cells. These sites of Mediator eviction were highly correlated with transcriptional suppression of neighboring genes, which are enriched for targets of the transcription factor MYB and for functions related to leukemogenesis. A shRNA screen of Mediator in AML cells identified the MED12, MED13, MED23, and MED24 subunits as performing a similar regulatory function to BRD4 in this context, including a shared role in sustaining a block in myeloid maturation. These findings suggest that the interaction between BRD4 and Mediator has functional importance for gene-specific transcriptional activation and for AML maintenance.

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Teaser

In this study, Bhagwat et al. show that the Mediator complex and BRD4 are linked coactivators that support gene-specific transcriptional activation in leukemia cells. They provide evidence that small-molecule inhibitors of BRD4 exert anti-leukemia effects by interfering with Mediator function to suppress transcription.


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CRISPR/Cas9-Derived Mutations Both Inhibit HIV-1 Replication and Accelerate Viral Escape

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Zhen Wang, Qinghua Pan, Patrick Gendron, Weijun Zhu, Fei Guo, Shan Cen, Mark A. Wainberg, Chen Liang
Cas9 cleaves specific DNA sequences with the assistance of a programmable single guide RNA (sgRNA). Repairing this broken DNA by the cell’s error-prone non-homologous end joining (NHEJ) machinery leads to insertions and deletions (indels) that often impair DNA function. Using HIV-1, we have now demonstrated that many of these indels are indeed lethal for the virus, but that others lead to the emergence of replication competent viruses that are resistant to Cas9/sgRNA. This unexpected contribution of Cas9 to the development of viral resistance is facilitated by some indels that are not deleterious for viral replication, but that are refractory to recognition by the same sgRNA as a result of changing the target DNA sequences. This observation illustrates two opposite outcomes of Cas9/sgRNA action, i.e., inactivation of HIV-1 and acceleration of viral escape, thereby potentially limiting the use of Cas9/sgRNA in HIV-1 therapy.

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Teaser

Wang et al. report that HIV-1 can escape Cas9/sgRNA-mediated inhibition. They reveal that the NHEJ repair machinery generates mutations in the HIV-1 Cas9 cleavage site that result in two outcomes: viral replication suppression and viral escape.


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Lithium Promotes Longevity through GSK3/NRF2-Dependent Hormesis

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Jorge Iván Castillo-Quan, Li Li, Kerri J. Kinghorn, Dobril K. Ivanov, Luke S. Tain, Cathy Slack, Fiona Kerr, Tobias Nespital, Janet Thornton, John Hardy, Ivana Bjedov, Linda Partridge
The quest to extend healthspan via pharmacological means is becoming increasingly urgent, both from a health and economic perspective. Here we show that lithium, a drug approved for human use, promotes longevity and healthspan. We demonstrate that lithium extends lifespan in female and male Drosophila, when administered throughout adulthood or only later in life. The life-extending mechanism involves the inhibition of glycogen synthase kinase-3 (GSK-3) and activation of the transcription factor nuclear factor erythroid 2-related factor (NRF-2). Combining genetic loss of the NRF-2 repressor Kelch-like ECH-associated protein 1 (Keap1) with lithium treatment revealed that high levels of NRF-2 activation conferred stress resistance, while low levels additionally promoted longevity. The discovery of GSK-3 as a therapeutic target for aging will likely lead to more effective treatments that can modulate mammalian aging and further improve health in later life.

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Teaser

The mood stabilizer lithium has been shown to extend lifespan in organisms ranging from yeast to flies. Castillo-Quan et al. show that lithium promotes longevity through GSK-3 inhibition and subsequent NRF-2 activation, suggesting that GSK3 is a possible drug target that might affect aging.


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Cdk1 Phosphorylates SPAT-1/Bora to Promote Plk1 Activation in C. elegans and Human Cells

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Yann Thomas, Luca Cirillo, Costanza Panbianco, Lisa Martino, Nicolas Tavernier, Françoise Schwager, Lucie Van Hove, Nicolas Joly, Anna Santamaria, Lionel Pintard, Monica Gotta
The conserved Bora protein is a Plk1 activator, essential for checkpoint recovery after DNA damage in human cells. Here, we show that Bora interacts with Cyclin B and is phosphorylated by Cyclin B/Cdk1 at several sites. The first 225 amino acids of Bora, which contain two Cyclin binding sites and three conserved phosphorylated residues, are sufficient to promote Plk1 phosphorylation by Aurora A in vitro. Mutating the Cyclin binding sites or the three conserved phosphorylation sites abrogates the ability of the N terminus of Bora to promote Plk1 activation. In human cells, Bora-carrying mutations of the three conserved phosphorylation sites cannot sustain mitotic entry after DNA damage. In C. elegans embryos, mutation of the three conserved phosphorylation sites in SPAT-1, the Bora ortholog, results in a severe mitotic entry delay. Our results reveal a crucial and conserved role of phosphorylation of the N terminus of Bora for Plk1 activation and mitotic entry.

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Teaser

Thomas et al. now find that Cyclin B/Cdk1 phosphorylates SPAT-1/Bora to promote Plk1 activation in C. elegans and in human cells. They identify three conserved phosphorylation sites in SPAT-1 and Bora that promote timely mitotic entry in the embryo and G2-checkpoint recovery from DNA damage in human cells.


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Common-Lymphoid-Progenitor-Independent Pathways of Innate and T Lymphocyte Development

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Maryam Ghaedi, Catherine A. Steer, Itziar Martinez-Gonzalez, Timotheus Y.F. Halim, Ninan Abraham, Fumio Takei
All lymphocytes are thought to develop from common lymphoid progenitors (CLPs). However, lymphoid-primed multipotent progenitors (LMPPs) are more efficient than CLPs in differentiating into T cells and group 2 innate lymphoid cells (ILC2s). Here, we have divided LMPPs into CD127⁻ (LMPP−s) and CD127⁺ (LMPP+s) subsets and compared them with Ly6D⁻ and Ly6D⁺ CLPs. Adult LMPP+s differentiated into T cells and ILCs more rapidly and efficiently than other progenitors in transplantation assays. The development of T cells and ILC2s is highly active in the neonatal period. Neonatal CLPs are rare and, unlike prominent neonatal LMPP+s, do not efficiently differentiate into T cells and ILC2s. ILC2s generated in the neonatal period are long lived and persist in adult tissues. These results suggest that some ILCs and T cells may develop from LMPP+s via CLP-independent pathways.

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Teaser

Ghaedi et al. report that individual lymphoid lineages can develop from multiple progenitors with varying probabilities. CD127⁺ LMPPs (LMPP+s) have a high probability of differentiating into the ILC and T cell lineages without differentiating into CLPs.


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Activation of P-TEFb by Androgen Receptor-Regulated Enhancer RNAs in Castration-Resistant Prostate Cancer

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Yu Zhao, Liguo Wang, Shancheng Ren, Lan Wang, Patrick R. Blackburn, Melissa S. McNulty, Xu Gao, Meng Qiao, Robert L. Vessella, Manish Kohli, Jun Zhang, R. Jeffrey Karnes, Donald J. Tindall, Youngsoo Kim, Robert MacLeod, Stephen C. Ekker, Tiebang Kang, Yinghao Sun, Haojie Huang
The androgen receptor (AR) is required for castration-resistant prostate cancer (CRPC) progression, but the function and disease relevance of AR-bound enhancers remain unclear. Here, we identify a group of AR-regulated enhancer RNAs (e.g., PSA eRNA) that are upregulated in CRPC cells, patient-derived xenografts (PDXs), and patient tissues. PSA eRNA binds to CYCLIN T1, activates P-TEFb, and promotes cis and trans target gene transcription by increasing serine-2 phosphorylation of RNA polymerase II (Pol II-Ser2p). We define an HIV-1 TAR RNA-like (TAR-L) motif in PSA eRNA that is required for CYCLIN T1 binding. Using TALEN-mediated gene editing we further demonstrate that this motif is essential for increased Pol II-Ser2p occupancy levels and CRPC cell growth. We have uncovered a P-TEFb activation mechanism and reveal altered eRNA expression that is related to abnormal AR function and may potentially be a therapeutic target in CRPC.

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Teaser

Zhao et al. show that a group of AR-regulated eRNAs, including the PSA eRNA, are upregulated in CRPC cells in culture as well as in patient specimens. The PSA eRNA binds to CYCLIN T1, activates P-TEFb, and increases Pol II-Ser2p and cell growth, and this effect is mediated through a TAR-L motif.


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Differential Dopamine Regulation of Ca2+ Signaling and Its Timing Dependence in the Nucleus Accumbens

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Immani Swapna, Brian Bondy, Hitoshi Morikawa
Dopamine action in the nucleus accumbens (NAc) is thought to drive appetitive behavior and Pavlovian reward learning. However, it remains controversial how dopamine achieves these behavioral effects by regulating medium spiny projection neurons (MSNs) of the NAc, especially on a behaviorally relevant timescale. Metabotropic glutamate receptor (mGluR)-induced Ca²⁺ signaling dependent on the Ca²⁺- releasing messenger inositol 1,4,5-triphosphate (IP3) plays a critical role in controlling neuronal excitability and synaptic plasticity. Here, we show that transient dopamine application facilitates mGluR/IP3-induced Ca²⁺ signals within a time window of ∼2–10 s in a subpopulation of MSNs in the NAc core. Dopamine facilitation of IP3-induced Ca²⁺ signaling is mediated by D1 dopamine receptors. In dopamine-insensitive MSNs, activation of A2A adenosine receptors causes enhancement of IP3-evoked Ca²⁺ signals, which is reversed by D2 dopamine receptor activation. These results show that dopamine differentially regulates Ca²⁺ signaling on the order of seconds in two distinct MSN subpopulations.

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Teaser

Swapna et al. demonstrate that transient dopamine (via D1 receptors) facilitates Ca²⁺ signaling on the order of seconds in a subpopulation of nucleus accumbens neurons. In a separate subpopulation, dopamine (via D2 receptors) does the opposite, reversing A2A adenosine receptor-mediated Ca²⁺ signal facilitation.


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Formation of Neuronal Circuits by Interactions between Neuronal Populations Derived from Different Origins in the Drosophila Visual Center

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Takumi Suzuki, Eri Hasegawa, Yasuhiro Nakai, Masako Kaido, Rie Takayama, Makoto Sato
A wide variety of neurons, including populations derived from different origins, are precisely arranged and correctly connected with their partner to establish a functional neural circuit during brain development. The molecular mechanisms that orchestrate the production and arrangement of these neurons have been obscure. Here, we demonstrate that cell-cell interactions play an important role in establishing the arrangement of neurons of different origins in the Drosophila visual center. Specific types of neurons born outside the medulla primordium migrate tangentially into the developing medulla cortex. During their tangential migration, these neurons express the repellent ligand Slit, and the two layers that the neurons intercalate between express the receptors Robo2 and Robo3. Genetic analysis suggests that Slit-Robo signaling may control the positioning of the layer cells or their processes to form a path for migration. Our results suggest that conserved axon guidance signaling is involved in the interactions between neurons of different origins during brain development.

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Teaser

Suzuki et al. show that cell-cell interactions play an important role in establishing the precise arrangement of neurons of different origins in the Drosophila visual center. They suggest that the mechanism is conserved from invertebrates to vertebrates and involves repulsive Slit-Robo signaling.


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Proinflammatory Cytokines Induce Endocrine Differentiation in Pancreatic Ductal Cells via STAT3-Dependent NGN3 Activation

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Ivan Achel Valdez, Ercument Dirice, Manoj K. Gupta, Jun Shirakawa, Adrian Kee Keong Teo, Rohit N. Kulkarni
A major goal of diabetes research is to develop strategies that replenish pancreatic insulin-producing beta cells. One emerging strategy is to harness pancreatic plasticity—the ability of pancreatic cells to undergo cellular interconversions—a phenomenon implicated in physiological stress and pancreatic injury. Here, we investigate the effects of inflammatory cytokine stress on the differentiation potential of ductal cells in a human cell line, in mouse ductal cells by pancreatic intraductal injection, and during the progression of autoimmune diabetes in the non-obese diabetic (NOD) mouse model. We find that inflammatory cytokine insults stimulate epithelial-to-mesenchymal transition (EMT) as well as the endocrine program in human pancreatic ductal cells via STAT3-dependent NGN3 activation. Furthermore, we show that inflammatory cytokines activate ductal-to-endocrine cell reprogramming in vivo independent of hyperglycemic stress. Together, our findings provide evidence that inflammatory cytokines direct ductal-to-endocrine cell differentiation, with implications for beta cell regeneration.

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Teaser

Valdez et al. report that inflammatory cytokine stress induces epithelial-to-mesenchymal transition (EMT) in human pancreatic ductal cells as well as STAT3-dependent NGN3 activation in vitro. Furthermore, they show that inflammatory cytokines activate endocrine reprogramming in mouse ductal cells in vivo independently of hyperglycemic stress.


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The Sperm TRP-3 Channel Mediates the Onset of a Ca2+ Wave in the Fertilized C. elegans Oocyte

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Jun Takayama, Shuichi Onami
Sperm induce Ca²⁺ waves in the fertilized egg by introducing soluble factors or by surface interactions, which activate egg Ca²⁺ channels. Involvement of sperm Ca²⁺ channels is predicted by the conduit model; however, this model has not been validated. In Caenorhabditis elegans, the sperm-specific TRP family Ca²⁺ channel TRP-3 mediates sperm-oocyte fusion. Here, using high-speed in vivo imaging and image analyses, we show that sperm induce an immediate local Ca²⁺ rise followed by a Ca²⁺ wave in fertilized C. elegans oocytes. Oocytes fertilized by rare trp-3 escaper sperm showed a lack of local rise and a delay in onset of the Ca²⁺ wave. Sperm Ca²⁺ imaging suggests that the local rise is not due to the bolus introduction of stored Ca²⁺. These results suggest that, along with its primary function in sperm-oocyte fusion, TRP-3 induces Ca²⁺ waves in fertilized oocytes, consistent with the conduit model.

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Teaser

Fertilization induces Ca²⁺ responses in the oocyte. By using high-speed in vivo imaging of fertilization in C. elegans, Takayama and Onami identified TRP-3 as a sperm Ca²⁺ channel required for the generation of a Ca²⁺ response in the fertilized oocyte.


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An Essential Role for COPI in mRNA Localization to Mitochondria and Mitochondrial Function

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Dmitry Zabezhinsky, Boris Slobodin, Doron Rapaport, Jeffrey E. Gerst
Nuclear-encoded mRNAs encoding mitochondrial proteins (mMPs) can localize directly to the mitochondrial surface, yet how mMPs target mitochondria and whether RNA targeting contributes to protein import into mitochondria and cellular metabolism are unknown. Here, we show that the COPI vesicle coat complex is necessary for mMP localization to mitochondria and mitochondrial function. COPI inactivation leads to reduced mMP binding to COPI itself, resulting in the dissociation of mMPs from mitochondria, a reduction in mitochondrial membrane potential, a decrease in protein import in vivo and in vitro, and severe deficiencies in mitochondrial respiration. Using a model mMP (OXA1), we observed that COPI inactivation (or mutation of the potential COPI-interaction site) led to altered mRNA localization and impaired cellular respiration. Overall, COPI-mediated mMP targeting is critical for mitochondrial protein import and function, and transcript delivery to the mitochondria or endoplasmic reticulum is regulated by cis-acting RNA sequences and trans-acting proteins.

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Teaser

Zabezhinsky et al. show that the vesicular transport complex COPI has additional functions in intracellular RNA trafficking. They provide evidence that COPI binds mRNAs encoding mitochondrial proteins and regulates their localization to mitochondria, enabling mitochondrial protein import, morphology, and function.


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Systematic Mutant Analyses Elucidate General and Client-Specific Aspects of Hsp90 Function

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Parul Mishra, Julia M. Flynn, Tyler N. Starr, Daniel N.A. Bolon
To probe the mechanism of the Hsp90 chaperone that is required for the maturation of many signaling proteins in eukaryotes, we analyzed the effects of all individual amino acid changes in the ATPase domain on yeast growth rate. The sensitivity of a position to mutation was strongly influenced by proximity to the phosphates of ATP, indicating that ATPase-driven conformational changes impose stringent physical constraints on Hsp90. To investigate how these constraints may vary for different clients, we performed biochemical analyses on a panel of Hsp90 mutants spanning the full range of observed fitness effects. We observed distinct effects of nine Hsp90 mutations on activation of v-src and glucocorticoid receptor (GR), indicating that different chaperone mechanisms can be utilized for these clients. These results provide a detailed guide for understanding Hsp90 mechanism and highlight the potential for inhibitors of Hsp90 that target a subset of clients.

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Teaser

Mishra et al. now examine the mechanism by which Hsp90 helps clients to mature by analyzing the effects of all individual mutations in the ATPase domain on yeast growth rate. The results indicate that both general and client-specific features of this domain contribute to chaperone function.


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The Actin-Binding Protein α-Adducin Is Required for Maintaining Axon Diameter

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Sérgio Carvalho Leite, Paula Sampaio, Vera Filipe Sousa, Joana Nogueira-Rodrigues, Rita Pinto-Costa, Luanne Laurel Peters, Pedro Brites, Mónica Mendes Sousa
The actin-binding protein adducin was recently identified as a component of the neuronal subcortical cytoskeleton. Here, we analyzed mice lacking adducin to uncover the function of this protein in actin rings. α-adducin knockout mice presented progressive axon enlargement in the spinal cord and optic and sciatic nerves, followed by axon degeneration and loss. Using stimulated emission depletion super-resolution microscopy, we show that a periodic subcortical actin cytoskeleton is assembled in every neuron type inspected including retinal ganglion cells and dorsal root ganglia neurons. In neurons devoid of adducin, the actin ring diameter increased, although the inter-ring periodicity was maintained. In vitro, the actin ring diameter adjusted as axons grew, suggesting the lattice is dynamic. Our data support a model in which adducin activity is not essential for actin ring assembly and periodicity but is necessary to control the diameter of both actin rings and axons and actin filament growth within rings.

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Teaser

Leite et al. show that adducin is not essential for the periodicity of neuronal actin rings but that it is necessary to control ring diameter. The authors propose that changes in neuronal actin rings may trigger axonal degeneration.


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MTAP Deletions in Cancer Create Vulnerability to Targeting of the MAT2A/PRMT5/RIOK1 Axis

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Katya Marjon, Michael J. Cameron, Phong Quang, Michelle F. Clasquin, Everton Mandley, Kaiko Kunii, Michael McVay, Sung Choe, Andrew Kernytsky, Stefan Gross, Zenon Konteatis, Joshua Murtie, Michelle L. Blake, Jeremy Travins, Marion Dorsch, Scott A. Biller, Kevin M. Marks
Homozygous deletions of p16/CDKN2A are prevalent in cancer, and these mutations commonly involve co-deletion of adjacent genes, including methylthioadenosine phosphorylase (MTAP). Here, we used shRNA screening and identified the metabolic enzyme, methionine adenosyltransferase II alpha (MAT2A), and the arginine methyltransferase, PRMT5, as vulnerable enzymes in cells with MTAP deletion. Metabolomic and biochemical studies revealed a mechanistic basis for this synthetic lethality. The MTAP substrate methylthioadenosine (MTA) accumulates upon MTAP loss. Biochemical profiling of a methyltransferase enzyme panel revealed that MTA is a potent and selective inhibitor of PRMT5. MTAP-deleted cells have reduced PRMT5 methylation activity and increased sensitivity to PRMT5 depletion. MAT2A produces the PRMT5 substrate S-adenosylmethionine (SAM), and MAT2A depletion reduces growth and PRMT5 methylation activity selectively in MTAP-deleted cells. Furthermore, this vulnerability extends to PRMT5 co-complex proteins such as RIOK1. Thus, the unique biochemical features of PRMT5 create an axis of targets vulnerable in CDKN2A/MTAP-deleted cancers.

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Teaser

Marjon et al. show that multiple synthetic lethal targets emerge in cancers with MTAP deletion. MTAP loss leads to the accumulation of its substrate, which inhibits the activity of the methyltransferase PRMT5 and sensitizes cancer cells to PRMT5 targeting. Enzymes supporting PRMT5 function, including MAT2A and PRMT5 binding partner, RIOK1, are also vulnerable.


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Enhanced CLIP Uncovers IMP Protein-RNA Targets in Human Pluripotent Stem Cells Important for Cell Adhesion and Survival

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Anne E. Conway, Eric L. Van Nostrand, Gabriel A. Pratt, Stefan Aigner, Melissa L. Wilbert, Balaji Sundararaman, Peter Freese, Nicole J. Lambert, Shashank Sathe, Tiffany Y. Liang, Anthony Essex, Severine Landais, Christopher B. Burge, D. Leanne Jones, Gene W. Yeo
Human pluripotent stem cells (hPSCs) require precise control of post-transcriptional RNA networks to maintain proliferation and survival. Using enhanced UV crosslinking and immunoprecipitation (eCLIP), we identify RNA targets of the IMP/IGF2BP family of RNA-binding proteins in hPSCs. At the broad region and binding site levels, IMP1 and IMP2 show reproducible binding to a large and overlapping set of 3′ UTR-enriched targets. RNA Bind-N-seq applied to recombinant full-length IMP1 and IMP2 reveals CA-rich motifs that are enriched in eCLIP-defined binding sites. We observe that IMP1 loss in hPSCs recapitulates IMP1 phenotypes, including a reduction in cell adhesion and increase in cell death. For cell adhesion, we find IMP1 maintains levels of integrin mRNA specifically regulating RNA stability of ITGB5 in hPSCs. Additionally, we show that IMP1 can be linked to hPSC survival via direct target BCL2. Thus, transcriptome-wide binding profiles identify hPSC targets modulating well-characterized IMP1 roles.

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Teaser

Using transcriptome-wide mapping with eCLIP, Conway et al. identify thousands of IMP1, IMP2, and IMP3 RNA binding sites in human stem cells, identifying both overlapping and distinct targets among IMP proteins. Two IMP1 targets, ITGB5 and BCL2, help mediate IMP1 roles in cell adhesion and survival.


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Variation in National Use of Long-Term ADT by Disease Aggressiveness Among Men With Unfavorable-Risk Prostate Cancer

Background: The current NCCN Clinical Practice Guidelines in Oncology for Prostate Cancer recommend long-term androgen deprivation therapy (ADT) for all men with high-risk prostate cancer treated with external-beam radiation therapy (EBRT). We determined whether the use of long-term ADT varied by the recently defined subcategories of high-risk disease (favorable, other, and very high) versus unfavorable intermediate-risk disease. Methods: We identified 5,524 patients with unfavorable-risk prostate cancer diagnosed from 2004 to 2007 and managed with EBRT using the SEER-Medicare linked database. Patients were stratified by risk group: unfavorable intermediate-risk, favorable high-risk (previously defined and validated as clinical stage T1c, Gleason score of 4 + 4 = 8, and prostate-specific antigen [PSA] level <10 ng/mL, or clinical stage T1c, Gleason score of 6, and PSA level >20 ng/mL), very-high-risk (clinical stage T3b–T4 or primary Gleason pattern 5), or other high risk (ie, neither favorable nor very high). We used multivariable competing risks regression to estimate the rates of long-term (≥2 years) ADT by group. Results: Men with favorable high-risk prostate cancer were significantly less likely to receive long-term ADT than those with other high-risk disease (15.4% vs 24.6%, adjusted hazard ratio [AHR], 0.68; 95% CI, 0.60–0.76; P<.001), and similarly likely as those with unfavorable intermediate-risk disease (AHR, 1.10; 95% CI, 0.99–1.23; P=.087). Other high-risk disease was less likely to receive long-term ADT than very high-risk cancer (24.6% vs 30.8%; AHR, 0.83; 95% CI, 0.74–0.93; P=.002). Conclusions: Despite current guidelines, patients with EBRT-managed high-risk prostate cancer received significantly different rates of long-course ADT based on subclassification. Our results suggest that oncologists view these patients as a heterogeneous group with favorable high-risk cancer warranting less aggressive therapy than other high-risk or very high-risk disease.

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NCCN News

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Molecular Profiling in Cutaneous Melanoma

Molecular profiling of malignant tumors is gaining increasing interest in oncology. In recent years, several molecular techniques have been studied in melanoma, with the goal to improve upon the diagnostic and prognostic abilities of currently available clinical and histopathologic parameters. Reliable tests performed early in the diagnosis and management of melanoma could lead to decreased morbidity and mortality by selecting appropriate patients for more-aggressive therapy and sparing those for whom it is not indicated. This article reviews the molecular diagnostic and prognostic techniques currently available for melanoma and evaluates their potential role in clinical practice.

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Letting Nature Loose

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Patterns of Palliative Care Consultation Among Elderly Patients With Cancer

Background: The role of palliative care has expanded over the past several decades, although the oncology-specific regional evolution of this specialty has not been characterized at the population-based level. Methods: This study defined the patterns of palliative care delivery using a retrospective cohort of patients with advanced cancer within the SEER-Medicare linked database. We identified 83,022 patients with metastatic breast, prostate, lung, and colorectal cancers. We studied trends between 2000 through 2009, and determined patient-level and regional-level predictors of palliative care delivery. Results: Palliative care consultation rates increased from 3.0% in 2000 to 12.9% in 2009, with most consultations occurring in the last 4 weeks of life (77%) in the inpatient hospital setting. The rates of palliative care delivery were highest in the West (7.6%) and lowest in the South (3.2%). The likelihood of palliative care consultation increased with decreasing numbers of regional acute care hospital beds per capita. The use of palliative care consultation increased with increasing numbers of regional physicians. The use of palliative care decreased with increasing regional Medicare expenditure with a $1,387 difference per beneficiary between the first and fourth quartiles of palliative care use. Conclusions: Geographic location influences a patient's options for palliative care in the United States. Although the overall rates of palliative care are increasing, future effort should focus on improving palliative care services in regions with the least access.

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NCCN Guidelines and Quality Cancer Care: Where Have We Come From, and Where Should We Be Going?

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Oncology Research Program

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Imatinib Treatment of Lymphangiomatosis (Generalized Lymphatic Anomaly)

Lymphangiomatosis (eg, generalized lymphatic anomaly) is an abnormal proliferation of lymphatic endothelial cells. It is often a childhood disease, but it may present in adulthood by infiltrating organs and cause obstruction, bleeding, or disruption of lymphatic flow. Pulmonary involvement may be mild or cause diffuse interstitial lung disease, airway obstruction, hemoptysis, chylothorax, chylopericardium, and culminate in respiratory failure. Treatment has been limited to surgical resection or drainage procedures because there is no accepted effective systemic therapy. This report presents a patient with lymphangiomatosis and life-threatening hemoptysis in whom positive immunostaining for c-KIT suggested upregulation of tyrosine kinase and whose disease was controlled with imatinib.

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The Cost of Initial Care for Medicare Patients With Advanced Ovarian Cancer

Objectives: In preparation for payment reform, we evaluated Medicare payments for the initial treatment of patients with advanced ovarian cancer and assessed factors responsible for variation. Methods: Using the linked SEER-Medicare database, we identified a cohort of 9,491 women aged 65 years or older with stage III/IV epithelial ovarian cancer diagnosed between 1995 and 2007. Diagnostic and procedural codes specific to the care of ovarian cancer were used to estimate total medical costs for the treatment of ovarian cancer. Costs were adjusted for geography and for inflation to the 2009 US dollar. NCCN Guideline–consistent care was defined as surgery and 6 cycles of chemotherapy. A generalized linear regression was performed to assess factors associated with variability in cost. Results: The mean total payment per patient in the initial treatment period was $65,908 (range of means, $30,745–$96,360). Increasing medical comorbidity, use of PET/CT, surgical complications, and readmissions were associated with increased costs. Treatment with NCCN Guideline–consistent surgery and chemotherapy had a mean annual cost of $85,987 compared with $89,149 for non–NCCN Guideline–consistent treatment with surgery and chemotherapy. The cost of surgery and chemotherapy that was not consistent with NCCN Guidelines was approximately $7,000 more than the cost of therapy that was consistent (P<.001) Conclusions: The financial burden of caring for patients with ovarian cancer is substantial. Treatment that is consistent with NCCN recommendations for treating advanced ovarian cancer, which is shown to have improved outcomes, is not associated with higher cost.

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NCCN Guidelines Insights: Multiple Myeloma, Version 3.2016

These NCCN Guidelines Insights highlight the important updates/changes specific to the 2016 version of the NCCN Clinical Practice Guidelines in Oncology for Multiple Myeloma. These changes include updated recommendations to the overall management of multiple myeloma from diagnosis and staging to new treatment options.

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Melanoma, Version 2.2016, NCCN Clinical Practice Guidelines in Oncology

This selection from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Melanoma focuses on adjuvant therapy and treatment of in-transit disease, because substantial changes were made to the recommendations for the 2016 update. Depending on the stage of the disease, options for adjuvant therapy now include biochemotherapy and high-dose ipilimumab. Treatment options for in-transit disease now include intralesional injection with talimogene laherparepvec (T-VEC), a new immunotherapy. These additions prompted re-assessment of the data supporting older recommended treatment options for adjuvant therapy and in-transit disease, resulting in extensive revisions to the supporting discussion sections.

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Guiding Lay Navigation in Geriatric Patients With Cancer Using a Distress Assessment Tool

Background: There is growing interest in psychosocial care and evaluating distress in patients with cancer. As of 2015, the Commission on Cancer requires cancer centers to screen patients for distress, but the optimal approach to implementation remains unclear. Methods: We assessed the feasibility and impact of using distress assessments to frame lay navigator interactions with geriatric patients with cancer who were enrolled in navigation between January 1, 2014, and December 31, 2014. Results: Of the 5,121 patients enrolled in our lay patient navigation program, 4,520 (88%) completed at least one assessment using a standardized distress tool (DT). Navigators used the tool to structure both formal and informal distress assessments. Of all patients, 24% reported distress scores of 4 or greater and 5.5% reported distress scores of 8 or greater. The most common sources of distress at initial assessment were pain, balance/mobility difficulties, and fatigue. Minority patients reported similar sources of distress as the overall program population, with increased relative distress related to logistical issues, such as transportation and financial/insurance questions. Patients were more likely to ask for help with questions about insurance/financial needs (79%), transportation (76%), and knowledge deficits about diet/nutrition (76%) and diagnosis (66%) when these items contributed to distress. Conclusions: Lay navigators were able to routinely screen for patient distress at a high degree of penetration using a structured distress assessment.

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Treatment Disparities Faced by Undocumented Workers From Low- and Middle-Income Countries in the United States With Hematologic Malignancies

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Hydroxycinnamic acid bound arabinoxylans from millet brans-structural features and antioxidant activity

Publication date: July 2016
Source:International Journal of Biological Macromolecules, Volume 88
Author(s): Vandana Bijalwan, Usman Ali, Atul Kumar Kesarwani, Kamalendra Yadav, Koushik Mazumder
Hydroxycinnamic acid bound arabinoxylans (HCA-AXs) were extracted from brans of five Indian millet varieties and response surface methodology was used to optimize the extraction conditions. The optimal condition to obtain highest yield of millet HCA-AXs was determined as follows: time 61min, temperature 66°C, ratio of solvent to sample 12ml/g. Linkage analysis indicated that hydroxycinnamic acid bound arabinoxylan from kodo millet (KM-HCA-AX) contained comparatively low branched arabinoxylan consisting of 14.6% mono-substituted, 1.2% di-substituted and 41.2% un-substituted Xylp residues. The HPLC analysis of millet HCA-AXs showed significant variation in the content of three major bound hydroxycinnamic acids (caffeic, p-coumaric and ferulic acid). The antioxidant activity of millet HCA-AXs were evaluated using three in vitro assay methods (DPPH, FRAP and β-carotene linoleate emulsion assays) which suggested both phenolic acid composition and structural characteristics of arabinoxylans could be correlated to their antioxidant potential, the detailed structural analysis revealed that low substituted KM-HCA-AX exhibited relatively higher antioxidant activity compared to other medium and highly substituted HCA-AXs from finger (FM), proso (PM), barnyard (BM) and foxtail (FOXM) millet.



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Molecular structure, chemical properties and biological activities of Pinto bean pod polysaccharide

Publication date: July 2016
Source:International Journal of Biological Macromolecules, Volume 88
Author(s): Fazlina Kamarudin, Chee-Yuen Gan
Pinto bean pod polysaccharide (PBPP) was successfully extracted with yield of 38.5g/100g and the PBPP gave total carbohydrate and uronic acid contents of 286.2mg maltose equivalent/g and 374.3mgGal/g, respectively. The Mw of PBPP was 270.6kDa with intrinsic viscosity of 0.262dm³/g, which composed of mannose (2.5%), galacturonic acid (15.0%), rhamnose (4.0%), glucose (9.0%), galactose (62.2%), xylose (2.9%) and arabinose (4.3%) with trace amount of ribose and fucose. The result suggested that PBPP has a spherical conformation with a highly branched structure. Fourier Transform Infrared analysis showed that PBPP has a similar structure as commercial pectin with an esterification degree of 59.9%, whereas scanning electron microscopy study showed that the crude polysaccharide formed a thin layer of film that was made of multiple micro strands of fibre. PBPP exhibited substantial free radical scavenging activity (7.7%), metal reducing capability (2.04mmol/dm³) and α-amylase inhibitory activity (97.6%) at a total amount of 1mg. PBPP also exhibited high water- and oil-holding capacities (3.6g/g and 2.8g/g, respectively). At a low concentration, PBPP exhibited emulsifying activity of 39.6% with stability of 38.6%. Apart from that, PBPP was able to show thickening capability at low concentration (0.005kg/dm³).



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Structural and thermodynamic properties of kappa class glutathione transferase from Camelus dromedarius

Publication date: July 2016
Source:International Journal of Biological Macromolecules, Volume 88
Author(s): Ajamaluddin Malik, Dalia Fouad, Nikolaos E. Labrou, Abdulrahman M. Al-Senaidy, Mohamed A. Ismael, Hesham M. Saeed, Farid S. Ataya
The Arabian camel, Camelus dromedarius is naturally adapted to extreme desert climate and has evolved protective mechanisms to limit oxidative stress. The mitochondrial kappa class glutathione transferase enzyme is a member of GST supergene family that represents an important enzyme group in cellular Phase II detoxification machinery and is involved in the protection against oxidative stress and xenobiotics. In the present study, C. dromedarius kappa class glutathione transferase (CdGSTK1-1) was cloned, expressed in E. coli BL21, purified and its structural, thermodynamic and unfolding pathway was investigated. The results showed that CdGSTK1-1 has unique trimeric structure, exhibits low thermostability and a complex equilibrium unfolding profile. It unfolds through three folding states with formation of thinly populated intermediate species. The melting points (Tm) of the first unfolding transition was 40.3±0.2°C and Tm of the second unfolding transition was 49.1±0.1°C. The van’t Hoff enthalpy of the first and second transition were 298.7±13.2 and 616.5±2.4kJ/mol, respectively. Moreover, intrinsic fluorescence and near-UV CD studies indicates that substrate binding does not leads to major conformational changes in CdGSTK1-1.



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Synthesis and characterization of antibacterial carboxymethyl Chitosan/ZnO nanocomposite hydrogels

Publication date: July 2016
Source:International Journal of Biological Macromolecules, Volume 88
Author(s): Fazli Wahid, Jun-Jiao Yin, Dong-Dong Xue, Han Xue, Yu-Shi Lu, Cheng Zhong, Li-Qiang Chu
The antibacterial carboxymethyl chitosan/ZnO nanocomposite hydrogels were successfully prepared via in situ formation of ZnO nanorods in the crosslinked carboxymethyl chitosan (CMCh) matrix, by treating the CMCh hydrogel matrix with zinc nitrate solution followed by the oxidation of zinc ions with alkaline solution. The resulting CMCh/ZnO hydrogels were characterized by using FTIR spectroscopy, X-ray diffractormetry and scanning electron microscopy (SEM). SEM micrographs revealed the formation of ZnO nanorods in the hydrogel matrix with the size ranging from 190nm to 600nm. The swelling behavior of the prepared nanocomposite hydrogels was also investigated in different pH solutions. The CMCh/ZnO nanocomposite hydrogel showed rather higher swelling behavior in different pH solutions in comparison with neat CMCh hydrogel. Furthermore, the antibacterial activity of CMCh/ZnO hydrogel was studied against Escherichia coli and Staphylococcus aureus by CFU assay. The results demonstrated an excellent antibacterial activity of the nanocomposite hydrogel. Therefore, the developed CMCh/ZnO nanocomposite hydrogel can be used effectively in biomedical field.



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Fabrication of porous gelatin-chitosan microcarriers and modeling of process parameters via the RSM method

Publication date: July 2016
Source:International Journal of Biological Macromolecules, Volume 88
Author(s): Mohammad Karimian S.A., Shohreh Mashayekhan, Hossein Baniasadi
Porous gelatin-chitosan microcarriers (MCs) with the size of 350±50μm were fabricated with blends of different gelatin/chitosan (G/C) weight ratio using an electrospraying technique. Response surface methodology (RSM) was used to study the quantitative influence of process parameters, including blend ratio, voltage, and syringe pump flow rate, on MCs diameter and density. In the following, MCs of the same diameter and different G/C weight ratio (1, 2, and 3) were fabricated and their porosity and biocompatibility were investigated via SEM images and MTT assay, respectively. The results showed that mesenchymal stem cells (MSCs) could attach, proliferate, and spread on fabricated porous MCs during 7 days of culturing especially on those prepared with a G/C weight ratio of 1. Such porous gelatin-chitosan MCs with a G/C weight ratio of 1 may be considered as a promising candidate for injectable carriers supporting attachment and proliferation of MSCs.



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New insights into xanthine oxidase behavior upon heating using spectroscopy and in silico approach

Publication date: July 2016
Source:International Journal of Biological Macromolecules, Volume 88
Author(s): Loredana Dumitrașcu, Nicoleta Stănciuc, Iuliana Aprodu
Thermal dependent conformational changes of xanthine oxidase (XOD) were studied using sensitive and non-destructive methods like fluorescence spectroscopy and molecular modeling in the temperature range of 25–85°C. Intrinsic fluorescence studies showed that the microenvironment of tryptophan and tyrosine residues becomes more exposed to solvent as the temperature increased up to 85°C, whereas in case of flavin cofactor is rather conserved. At higher temperatures, the flavin adenine dinucleotide is displaced from the core of the protein, but is not fully released as shown by the Stern Volmer quenching constant and accessible fraction of the cofactor. Anyway, no significant changes in the structure of XOD monomer were identified after running molecular dynamics simulations at temperatures 25°C, 65°C and 85°C. Therefore, we can conclude that the most important changes in the protein structure at thermal treatment mainly consist on molecular aggregation and dissociation events.



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Efficacy and External Validity of Electronic and Mobile Phone-Based Interventions Promoting Vegetable Intake in Young Adults: Systematic Review and Meta-Analysis

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Combined chemotherapy and radiation therapy assists low-grade glial brain tumors

The addition of chemotherapy to radiation therapy prolongs survival among adults with low-grade glial brain tumors

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Viruses, Vol. 8, Pages 94: Virus-Like Particle Vaccination Protects Nonhuman Primates from Lethal Aerosol Exposure with Marburgvirus (VLP Vaccination Protects Macaques against Aerosol Challenges)

Marburg virus (MARV) was the first filovirus to be identified following an outbreak of viral hemorrhagic fever disease in Marburg, Germany in 1967. Due to several factors inherent to filoviruses, they are considered a potential bioweapon that could be disseminated via an aerosol route. Previous studies demonstrated that MARV virus-like particles (VLPs) containing the glycoprotein (GP), matrix protein VP40 and nucleoprotein (NP) generated using a baculovirus/insect cell expression system could protect macaques from subcutaneous (SQ) challenge with multiple species of marburgviruses. In the current study, the protective efficacy of the MARV VLPs in conjunction with two different adjuvants: QS-21, a saponin derivative, and poly I:C against homologous aerosol challenge was assessed in cynomolgus macaques. Antibody responses against the GP antigen were equivalent in all groups receiving MARV VLPs irrespective of the adjuvant; adjuvant only-vaccinated macaques did not demonstrate appreciable antibody responses. All macaques were subsequently challenged with lethal doses of MARV via aerosol or SQ as a positive control. All MARV VLP-vaccinated macaques survived either aerosol or SQ challenge while animals administered adjuvant only exhibited clinical signs and lesions consistent with MARV disease and were euthanized after meeting the predetermined criteria. Therefore, MARV VLPs induce IgG antibodies recognizing MARV GP and VP40 and protect cynomolgus macaques from an otherwise lethal aerosol exposure with MARV.

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Hyperintense lesion along the pyramidal tract on DWI in hypoglycaemic hemiplegia

Description

An 85-year-old man with type 2 diabetes mellitus presented to our emergency department with sudden right limb weakness and dysarthria 90 min after onset. He was alert when examined and had a blood pressure of 163/89 mm Hg. Although right hemiplegia with facial weakness and dysarthria were noted, sensations to pinpricks were intact. MRI showed a hyperintense lesion in the posterior limb of the left internal capsule (IC), with decreased apparent diffusion coefficient values on diffusion-weighted imaging (DWI), suggesting acute ischaemic stroke (AIS) (figure 1). In the coronal plane, the lesion appeared along the pyramidal tract, suggesting a pathology other than AIS. A laboratory examination revealed a decrease in the serum glucose level (32 mg/dL), whereon 40 mL of a 50% glucose solution was infused. The patient made a complete recovery without neurological deficits; follow-up MRI 2 days later revealed complete lesion resolution (figure 2). Based on the clinical...

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Superior mesenteric artery occlusion as the manifestation of left atrial myxoma: an extremely rare occurrence

Description

A 62-year-old woman was presented to the surgical ward, with severe abdominal pain and vomiting. She had sinus tachycardia (135/min) and her blood pressure was 80/60 mm Hg. The physical examination revealed generalised abdominal distension with signs of peritonitis. Laboratory parameters revealed polymorphonuclear leucocytosis (total leucocyte count of 21 000/mm³ with 88% neutrophils), blood urea nitrogen=74 mg/dL and serum creatinine=2.1 mg/dL. X-ray of the abdomen showed air under the diaphragm. CT angiography revealed absence of contrast beyond the mid segment of the superior mesenteric artery (SMA) (figure 1). A large filling defect was noted in the left atrium (LA) on CT scan (figure 2). Echocardiogram also demonstrated a large 3.1x3.2 cm rounded, mobile mass in the left atrium, which was heterogeneous in echogenicity (figure 3A). It was attached to the interatrial septum in the region of the fossa ovalis. The LA appendage was clear (figure...

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Inflammatory breast cancer in a previously treated case of breast cancer: a diagnostic dilemma for the clinician

Inflammatory breast cancer (IBC) is a relatively rare and aggressive subtype, accounting for nearly 2.5% of all diagnosed breast cancers worldwide. It is usually characterised by an acute onset, rapid clinical progression, poor prognosis and micrometastasis at the time of presentation. Prompt recognition of clinical symptoms and identification of warning signs are vital in diagnosing and appropriately treating a patient with IBC.

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Adenocarcinoma of the ampulla of Vater metastasising into the right ventricle

A 43-year-old woman, after resected adenocarcinoma of the ampulla of Vater, presented dyspnoea and beginning signs of right heart failure. Echocardiography revealed a mass within the right ventricle (RV) suspicious for a metastasis of the known adenocarcinoma. The decision for surgical resection was made by cardiovascular MR, which was able to delineate the infiltrative growth of a metastasis. An extensive resection had to be performed. Parts of the intraventricular septum as well as the tricuspid valve had to be resected. After six cycles of adjuvant systemic chemotherapy with gemcitabine and nab-paclitaxel, the patient had no macroscopic tumour recurrence. To our knowledge, this is the first report of a pancreatobiliary tumour metastasising exclusively to the RV of the heart. We conclude that in this special case aggressive surgical management following chemotherapy was very effective in controlling the disseminated adenocarcinoma of the ampulla of Vater.

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Complete reversal of hypertensive cardiomyopathy after initiating combined antihypertensive therapy

Hypertensive cardiomyopathy is a common complication of hypertension, with a prevalence ranging from 12% to 26%. It is associated with an increased cardiac mortality and morbidity. Lifestyle changes and antihypertensive therapy usually have a significant, but relatively small effect on left ventricular hypertrophy (LVH), which is associated with a reduction in cardiovascular risk. In this paper, we describe a 39-year-old woman with severe LVH. On transthoracic echocardiogram there was concentric LVH, systolic function was a mildly reduced and there was diastolic dysfunction grade III. After only 6 months of therapy with a combination of antihypertensive agents, the left ventricular mass index was reduced by 29%, systolic function was normal and the diastolic dysfunction improved to grade I. This paper shows that in hypertensive cardiomyopathy, even severe LVH can be completely reversible.

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Mesenteric Meckel's diverticulum: an unusual cause of small bowel intussusception

Meckel's diverticulum (MD) is the commonest congenital anomaly of the small intestine, affecting 1–4% of the population. Cardinal features emphasise an antimesenteric location two feet proximal to the ileocaecal valve, with a separate mesenteric blood supply and involvement of all layers of the small intestine. However, reports of MD arising from the mesenteric border of the small intestine are rare in the surgical literature. This report examines the case of a 45-year-old woman presenting with a 6-month history of episodic central abdominal pain and microcytic anaemia who underwent an elective diagnostic laparoscopy as initial CT findings were inconclusive. Intraoperatively, she was found to have small bowel intussusception approximately 40 cm proximal to the ileocaecal valve. Macroscopic examination of the resected small bowel segment revealed a mesenteric outpouching that was confirmed as mesenteric MD on histopathological analysis. Postoperatively, the patient recovered with no surgical complications and full symptom resolution.

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Hypoglycaemic encephalopathy

Description

A 49-year-old man with a history of type 1 diabetes self-presented to hospital, with ataxia and memory impairment. Admission blood glucose was 1.9 mmol/L. Using a combination of intravenous and orally administered glucose, the patient became euglycaemic 45 min later. Marked cognitive impairment was noted to persist several days into his admission. An MRI of the brain scan was performed, demonstrating numerous foci of restricted diffusion involving the anterior and posterior territories (figures 1 and 2), including the cortex, subcortical white matter, deep white matter and corpus callosum. Blood tests for autoimmune, inflammatory and thrombogenic conditions, telemetry, echocardiography and angiographic studies of the extra and intracranial vessels, failed to demonstrate evidence of a thrombotic cause. The presence of multiple territory changes involving deep and cortical regions in the absence of vascular pathology made hypoglycaemic encephalopathy the only explanation for the presentation and findings.

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Sign of Leser-Trelat

Description

An 87-year-old woman presented with severe iron deficiency anaemia (haemoglobin 57 g/L). She also described a recent increase in the number of pigmented skin lesions on her trunk, which had become mildly pruritic. Her history included a right hemicolectomy 12 years earlier for tubulovillous adenoma and suspicion of malignant transformation. At that time, her serum carcinoembryonic antigen (CEA) had been normal and resection histology revealed complete margins with no evidence of malignancy. Unfortunately, she had declined colonoscopy surveillance following this.

On examination, she was found to have extensive seborrhoeic keratoses, which had recently increased in size and number (figure 1). Although the patient preferred to avoid colonoscopy, further investigations for an underlying malignancy were pursued. A CT scan of the abdomen showed suspicious bowel thickening suggestive of colorectal malignancy (figures 2 and 3) and a serum CEA was markedly elevated (167 µg/L). These findings...

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Alopecia areata and narcolepsy: a tale of obscure autoimmunity

Alopecia areata is an autoimmune dermatological disorder characterised by loss of hair in one or more discrete patches over the scalp. It has been linked to multiple disorders having an autoimmune origin. Like many autoimmune disorders it tends to be more common in females. To date, only five cases have been reported where alopecia has been associated with narcolepsy. Male gender is less commonly affected by alopecia areata. No case of alopecia areata in males has been associated with narcolepsy to the best of our knowledge. The current case represents the first ever-reported case of alopecia areata in a male patient with narcolepsy type 1. This coexistence is most likely the manifestation of a common underlying pathoimmunological mechanism that has not been completely understood, rather than a random association.

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