Medical Writing Competency Model - Section 1: Functions, Tasks, and Activities.

This article provides Section 1 of the 2017 Edition 2 Medical Writing Competency Model that describes the core work functions and associated tasks and activities related to professional medical writing within the life sciences industry. The functions in the Model are scientific communication strategy; document preparation, development, and finalization; document project management; document template, standard, format, and style development and maintenance; outsourcing, alliance partner, and client management; knowledge, skill, ability, and behavior development and sharing; and process improvement. The full Model also includes Section 2, which covers the knowledge, skills, abilities, and behaviors needed for medical writers to be effective in their roles; Section 2 is presented in a companion article. Regulatory, publication, and other scientific writing as well as management of writing activities are covered. The Model was developed to aid medical writers and managers within the life sciences industry regarding medical writing hiring, training, expectation and goal setting, performance evaluation, career development, retention, and role value sharing to cross-functional partners.

Medical Writing Competency Model - Section 2: Knowledge, Skills, Abilities, and Behaviors.

This article provides Section 2 of the 2017 Edition 2 Medical Writing Competency Model that describes the knowledge, skills, abilities, and behaviors that professional medical writers need in order to perform effectively within the life sciences industry. What a medical writer should know, what they should be able to do, and how they should use this knowledge and these skills to facilitate their primary work function is a focus. Regulatory, publication, and other scientific writing as well as management of writing activities are covered. The full Model also includes Section 1, which covers the core work functions and associated tasks and activities related to professional medical writing within the life sciences industry; Section 1 is included in a companion article. The Model was developed to aid medical writers and managers within the life sciences industry regarding medical writing hiring, training, expectation and goal setting, performance evaluation, career development, retention, and role value sharing to cross-functional partners.

Preclinical pharmacology and pharmacokinetics of CERC-301, a GluN2B-selective N-methyl-D-aspartate receptor antagonist.

The preclinical pharmacodynamic and pharmacokinetic properties of 4-methylbenzyl (3S, 4R)-3-fluoro-4-[(Pyrimidin-2-ylamino) methyl] piperidine-1-carboxylate (CERC-301), an orally bioavailable selective N-methyl-D-aspartate (NMDA) receptor subunit 2B (GluN2B) antagonist, were characterized to develop a translational approach based on receptor occupancy (RO) to guide CERC-301 dose selection in clinical trials of major depressive disorder. CERC-301 demonstrated high-binding affinity (K i, 8.1 nmol L(-1)) specific to GluN2B with an IC 50 of 3.6 nmol L(-1) and no off-target activity. CERC-301 efficacy was demonstrated in the forced swim test with an efficacy dose (ED 50) of 0.3-0.7 mg kg(-1) (RO, 30-50%); increase in locomotor activity was observed at ED 50 of 2 mg kg(-1), corresponding to an RO of 75%. The predicted 50% RO concentration (Occ50) in humans was 400 nmol L(-1), similar to that predicted for rat, dog, and monkey (300, 200, and 400 nmol L(-1), respectively). Safety pharmacology and neurotoxicity studies raised no specific safety concerns. A first-in-human study in healthy males demonstrated a dose-proportional pharmacokinetic profile, with T max of ~1 h and t 1/2 of 12-17 h. Based on the preclinical and pharmacodynamic data, doses of ≥8 mg in humans are hypothesized to have an acceptable safety profile and result in clinically relevant peak plasma exposure.

Larazotide acetate regulates epithelial tight junctions in vitro and in vivo.

Tight junctions (TJs) control paracellular permeability and apical-basolateral polarity of epithelial cells, and can be regulated by exogenous and endogenous stimuli. Dysregulated permeability is associated with pathological conditions, such as celiac disease and inflammatory bowel disease. Herein we studied the mechanism by which larazotide acetate, an 8-mer peptide and TJ regulator, inhibits the cellular changes elicited by gliadin fragments, AT-1002, and cytokines. Previously, we demonstrated that AT-1002, a 6-mer peptide derived from the Vibrio cholerae zonula occludens toxin ZOT, caused several biochemical changes in IEC6 and Caco-2 cells resulting in decreased transepithelial electrical resistance (TEER) and increased TJ permeability. In this study, larazotide acetate inhibited the redistribution and rearrangement of zonula occludens-1 (ZO-1) and actin caused by AT-1002 and gliadin fragments in Caco-2 and IEC6 cells. Functionally, larazotide acetate inhibited the AT-1002-induced TEER reduction and TJ opening in Caco-2 cells. Additionally, larazotide acetate inhibited the translocation of a gliadin 13-mer peptide, which has been implicated in celiac disease, across Caco-2 cell monolayers. Further, apically applied larazotide acetate inhibited the increase in TJ permeability elicited by basolaterally applied cytokines. Finally, when tested in vivo in gliadin-sensitized HLA-HCD4/DQ8 double transgenic mice, larazotide acetate inhibited gliadin-induced macrophage accumulation in the intestine and preserved normal TJ structure. Taken together, our data suggest that larazotide acetate inhibits changes elicited by AT-1002, gliadin, and cytokines in epithelial cells and preserves TJ structure and function in vitro and in vivo.

Larazotide acetate promotes tight junction assembly in epithelial cells.

Tight junctions (TJ) control paracellular permeability and apical-basolateral polarity of epithelial cells. Dysregulated permeability is associated with pathological conditions, such as celiac disease and inflammatory bowel disease. TJ formation is dependent on E-cadherin-mediated cell-cell adhesion and actin rearrangement, and is regulated by the Rho family GTPase and aPKC signaling pathways. Larazotide acetate, an 8-mer peptide and TJ modulator, inhibits TJ disassembly and dysfunction caused by endogenous and exogenous stimuli in intestinal epithelial cells. Here, we examined the effect of larazotide acetate on de novo TJ assembly using 2 different model systems. In MDCK cells, larazotide acetate promoted TJ assembly in a calcium switch assay. Larazotide acetate also promoted actin rearrangement, and junctional distribution of zonula occludens-1 (ZO-1), occludin, claudins, and E-cadherin. Larazotide acetate promoted TJ maturation and decreased paracellular permeability in "leaky" Caco-2 cells. Taken together, our data indicate that larazotide acetate enhances TJ assembly and barrier function by promoting actin rearrangement and redistribution of TJ and AJ proteins.

Mechanism of action of ZOT-derived peptide AT-1002, a tight junction regulator and absorption enhancer.

Tight junctions (TJs) are intercellular structures that control paracellular permeability and epithelial polarity. It is now accepted that TJs are highly dynamic structures that are regulated in response to exogenous and endogenous stimuli. Here, we provide details on the mechanism of action of AT-1002, the active domain of Vibrio cholerae's second toxin, zonula occludens toxin (ZOT). AT-1002, a hexamer peptide, caused the redistribution of ZO-1 away from cell junctions as seen by fluorescence microscopy. AT-1002 also activated src and mitogen activated protein (MAP) kinase pathways, increased ZO-1 tyrosine phosphorylation, and rearrangement of actin filaments. Functionally, AT-1002 caused a reversible reduction in transepithelial electrical resistance (TEER) and an increase in lucifer yellow permeability in Caco-2 cell monolayers. In vivo, co-administration of salmon calcitonin with 1 mg of AT-1002 resulted in a 5.2-fold increase in AUC over the control group. Our findings provide a mechanistic explanation for AT-1002-induced tight junction disassembly, and demonstrate that AT-1002 can be used for delivery of other agents in vivo.

aPKC-PAR complex dysfunction and tight junction disassembly in renal epithelial cells during ATP depletion.

Renal ischemia and in vitro ATP depletion result in disruption of the epithelial tight junction barrier, which is accompanied by breakdown of plasma membrane polarity. Tight junction formation is regulated by evolutionarily conserved complexes, including that of atypical protein kinase C (aPKC), Par3, and Par6. The aPKC signaling complex is activated by Rac and regulated by protein phosphorylation and associations with other tight junction regulatory proteins, for example, mLgl. In this study, we examined the role of aPKC signaling complex during ATP depletion and recovery in Madin-Darby canine kidney cells. ATP depletion reduced Rac GTPase activity and induced Par3, aPKCzeta, and mLgl-1 redistribution from sites of cell-cell contact, which was restored following recovery from ATP depletion. Zonula occludens (ZO)-1 and Par3 phosphorylation was reduced and association of aPKCzeta with its substrates Par3 and mLgl-1 was stabilized in ATP-depleted Madin-Darby canine kidney cells. ATP depletion also induced a stable association of Par3 with Tiam-1, a Rac GTPase exchange factor, which explains how aPKCzeta and Rac activities were suppressed. Experimental inhibition of aPKCzeta during recovery from ATP depletion interfered with reassembly of ZO-1 and Par3 at cell junctions. These data indicate that aPKC signaling is impaired during ATP depletion, participates in tight junction disassembly during cell injury and is important for tight junction reassembly during recovery.

Differential regulation of junctional complex assembly in renal epithelial cell lines.

Several signaling pathways that regulate tight junction and adherens junction assembly are being characterized. Calpeptin activates stress fiber assembly in fibroblasts by inhibiting SH2-containing phosphatase-2 (SHP-2), thereby activating Rho-GTPase signaling. Here, we have examined the effects of calpeptin on stress fiber and junctional complex assembly in Madin-Darby canine kidney (MDCK) and LLC-PK epithelial cells. Calpeptin induced disassembly of stress fibers and inhibition of Rho GTPase activity in MDCK cells. Interestingly, calpeptin augmented stress fiber formation in LLC-PK epithelial cells. Calpeptin treatment of MDCK cells resulted in a displacement of zonula occludens-1 (ZO-1) and occludin from cell-cell junctions and a loss of phosphotyrosine on ZO-1 and ZO-2, without any detectable effect on tight junction permeability. Surprisingly, calpeptin increased paracellular permeability in LLC-PK cells even though it did not affect tight junction assembly. Calpeptin also modulated adherens junction assembly in MDCK cells but not in LLC-PK cells. Calpeptin treatment of MDCK cells induced redistribution of E-cadherin and beta-catenin from intercellular junctions and reduced the association of p120ctn with the E-cadherin/catenin complex. Together, our studies demonstrate that calpeptin differentially regulates stress fiber and junctional complex assembly in MDCK and LLC-PK epithelial cells, indicating that these pathways may be regulated in a cell line-specific manner.

Testing effects of signal transduction pathways on cadherin junctional complex assembly using quantitative image analysis.

Cadherin adhesion molecules function in numerous cell biological processes that influence embryo development, normal cell physiology, and pathophysiology of many disease processes. Cadherins nucleate the assembly of the adherens junction, a cell-to-cell adhesion plaque that is prominent in simple epithelial cells and found in many cell types. Numerous cell biological approaches have been used to study this interesting class of molecules. Here, we outline methodology used in our studies of junctional complexes to examine effects of signaling molecules on assembly mechanisms. This is a quantitative method that allows the investigator to test the combined effect of two different signaling processes to determine whether these two signals act in concert within the same pathway. We discuss how this method could be generalized to other studies to examine consequences of various experimental manipulations on the assembly of cellular structures.

Rac1, but not RhoA, signaling protects epithelial adherens junction assembly during ATP depletion.

Rho family GTPase signaling regulates actin cytoskeleton and junctional complex assembly. Our previous work showed that RhoA signaling protects tight junctions from damage during ATP depletion. Here, we examined whether RhoA GTPase signaling protects adherens junction assembly during ATP depletion. Despite specific RhoA signaling- and ATP depletion-induced effects on adherens junction assembly, RhoA signaling did not alter adherens junction disassembly rates during ATP depletion. This shows that RhoA signaling specifically protects tight junctions from damage during ATP depletion. Rac1 GTPase signaling also regulates adherens junction assembly and therefore may regulate adherens junction assembly during ATP depletion. Indeed, we found that Rac1 signaling protects adherens junctions from damage during ATP depletion. Adherens junctions are regulated by various GTPases, including RhoA and Rac1, but adherens junctions are specifically protected by Rac1 signaling.