An allosteric modulator of the alpha7 nicotinic acetylcholine receptor possessing cognition-enhancing properties in vivo

Augmentation of nicotinic alpha7 receptor function is considered to be a potential therapeutic strategy aimed at ameliorating cognitive and mnemonic dysfunction in relation to debilitating pathological conditions, such as Alzheimer's disease and schizophrenia. In the present report, a novel positive allosteric modulator of the alpha7 nicotinic acetylcholine receptor (nAChR), 1-(5-chloro-2-hydroxy-phenyl)-3-(2-chloro-5-trifluoromethyl-phenyl)-urea (NS1738), is described. NS1738 was unable to displace or affect radioligand binding to the agonist binding site of nicotinic receptors, and it was devoid of effect when applied alone in electrophysiological paradigms. However, when applied in the presence of acetylcholine (ACh), NS1738 produced a marked increase in the current flowing through alpha7 nAChRs, as determined in both oocyte electrophysiology and patch-clamp recordings from mammalian cells. NS1738 acted by increasing the peak amplitude of ACh-evoked currents at all concentrations; thus, it increased the maximal efficacy of ACh. Oocyte experiments indicated an increase in ACh potency as well. NS1738 had only marginal effects on the desensitization kinetics of alpha7 nAChRs, as determined from patch-clamp studies of both transfected cells and cultured hippocampal neurons. NS1738 was modestly brain-penetrant, and it was demonstrated to counteract a (-)-scopolamine-induced deficit in acquisition of a water-maze learning task in rats. Moreover, NS1738 improved performance in the rat social recognition test to the same extent as (-)-nicotine, demonstrating that NS1738 is capable of producing cognitive enhancement in vivo. These data support the notion that alpha7 nAChR allosteric modulation may constitute a novel pharmacological principle for the treatment of cognitive dysfunction.     

Oncogenic mutations in histologically normal endometrium: the new normal?

The advent of next generation sequencing has vastly improved the resolution of mutation detection, thereby both increasing the resolution of the analysis of cancer tissues and shining light on the existence of somatic driver mutations in normal tissues, even in the absence of cancer. Studies have described somatic driver mutations in normal skin, blood, peritoneal washings, and esophageal epithelium. Such findings prompt speculation on whether such mutations exist in other tissues, such as the eutopic endometrium in particular, due to the highly regenerative nature of the endometrium and the recent observation of recurrent somatic driver mutations in deep infiltrating and iatrogenic endometriosis (tissues believed to be derived from the eutopic endometrium) by our group and others. In the current study we investigated the presence of somatic driver mutations in histologically normal endometrium from women lacking evidence of gynecologic malignancy or endometrial hyperplasia. Twenty-five women who underwent hysterectomies and 85 women who underwent endometrial biopsies were included in this study. Formalin-fixed, paraffin-embedded tissue specimens were analyzed by means of targeted sequencing followed by orthogonal validation with droplet digital PCR. PTEN and ARID1A immunohistochemistry (IHC) was also performed as surrogates for inactivating mutations in the respective genes. Overall, we observed somatic driver-like events in over 50% of normal endometrial samples analyzed, including hotspot mutations in KRAS, PIK3CA, and FGFR2 as well as PTEN-loss by IHC. Analysis of anterior and posterior samplings collected from women who underwent hysterectomies was consistent with the presence of somatic driver mutations within clonal pockets spread throughout the uterus. The prevalence of such oncogenic mutations also increased with age (OR: 1.05 [95% CI: 1.00–1.10], p = 0.035). These findings have implications on our understanding of aging and so-called ‘normal tissues’, thereby necessitating caution in the utilization of mutation-based early detection tools for endometrial or other cancers. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Industry sponsorship and research outcome: systematic review with meta-analysis

Purpose

Clinical research is widely sponsored by drug and device companies. We investigated whether industry sponsored drug and device studies have more favorable outcomes and differ in risk of bias, compared with studies having other sources of sponsorship. This review is an update of a previous Cochrane review.

Methods

In this update we searched MEDLINE and Embase (2010 to February 2015), Cochrane Methodology Register (2015, Issue 2) and Web of Science (June 2015). We included empirical studies that quantitatively compared primary research studies of drugs or medical devices sponsored by industry with studies with other sources of sponsorship. Two assessors included papers, extracted data and assessed risk of bias. Outcomes included favorable results, favorable conclusions, effect size, risk of bias and whether conclusions agreed with results.

Results

We included 27 additional papers in this update (review now includes 75 papers). Industry sponsored studies more often had favorable efficacy results, RR: 1.27 (95% CI 1.17–1.37), no difference in harms results RR: 1.37 (95% CI 0.64–2.93) and more often favorable conclusions RR: 1.34 (95% CI 1.19–1.51) compared with non-industry sponsored studies. Nineteen papers reported on sponsorship and efficacy effect size, but could not be pooled due to differences in reporting of data and heterogeneity of results. Comparing industry and non-industry sponsored studies, we did not find a difference in risk of bias from sequence generation, allocation concealment, follow-up and selective outcome reporting. However, industry sponsored studies more often had low risk of bias from blinding, RR: 1.25 (95% CI 1.05–1.50), compared with non-industry sponsored studies.

Conclusions

Drug and device studies sponsored by manufacturing companies have more favorable efficacy results and conclusions than studies sponsored by other sources.

     

Sialic Acid Residues Are Essential for Cell Lysis Mediated by Leukotoxin from Aggregatibacter actinomycetemcomitans

Leukotoxin (LtxA) from Aggregatibacter actinomycetemcomitans is known to target and lyse β₂-integrin-expressing cells such as polymorphonuclear leukocytes and macrophages. LtxA is an important virulence factor that facilitates chronic inflammation and is strongly associated with a fast-progressing form of periodontitis caused by the JP2 clone of the bacterium. Here, we show that sialic acid residues are important for LtxA-induced cell lysis, regardless of whether the cell express β₂-integrin or not. Clearly, removal of sialic acid groups significantly reduces a β₂-integrin-specific LtxA-induced lysis. Moreover, sialic acid presented on alternative proteins, such as, for instance, on erythrocytes that do not express β₂-integrin, also makes the cells more sensitive to LtxA. The data also illustrate the importance of the negative charge in order for the sialic acid to associate LtxA with the membrane. Removal of sialic acid is in itself sufficient to significantly reduce the negative charge on the erythrocytes. Moreover, we found that on human erythrocytes there is a positive association between the sensitivity to LtxA and the amount of negative charge caused by sialic acid. Interestingly, these features are not shared by all RTX toxins, since α-hemolysin from Escherichia coli induced cell lysis of both β₂-integrin-expressing and nonexpressing cells and this lysis is independent of the presence of sialic acid residues. In conclusion, LtxA not only is cytotoxic to β₂-integrin-expressing cells but can potentially initiate cell lysis in all cells that present a sufficient density of sialic acid groups on their plasma membrane.     

Lipoprotein-associated phospholipase A2 concentrations in plasma are associated with the extent of coronary artery disease and correlate to adipose tissue levels of marine n-3 fatty acids

Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) is an emerging risk factor for cardiovascular disease. In the present study, plasma levels of Lp-PLA(2) were measured in patients (n=301) admitted to elective coronary angiography because of suspected coronary artery disease (CAD). In a multiple linear regression analysis, the degree of CAD (0-, 1-, 2- or 3-vessel disease) and plasma LDL cholesterol significantly correlated to Lp-PLA(2) levels. Also the content of the marine n-3 fatty acid, eicosapentaenoic acid (EPA) in adipose tissue, a measure of long-term intake of seafood independently and inversely (r=-0.18, p<0.01) correlated with plasma levels of Lp-PLA(2). The results support the view that Lp-PLA(2) may relate to CAD and that intake of marine n-3 fatty acids might reduce plasma Lp-PLA(2) suggesting another mechanism by which n-3 fatty acids could reduce the risk of cardiovascular disease.     

Prion propagation, toxicity and degradation

Prion science has been on a rollercoaster for two decades. In the mid 1990s, the specter of mad cow disease (bovine spongiform encephalopathy, BSE) provoked an unprecedented public scare that was first precipitated by the realization that this animal prion disease could be transmitted to humans and then rekindled by the evidence that BSE-infected humans could pass on the infection through blood transfusions. Along with the gradual disappearance of BSE, the interest in prions has waned with the general public, funding agencies and prospective PhD students. In the past few years, however, a bewildering variety of diseases have been found to share features with prion infections, including cell-to-cell transmission. Here we review these developments and summarize those open questions that we currently deem most interesting in prion biology: how do prions damage their hosts, and how do hosts attempt to neutralize invading prions?     

Explorative study of pharmacokinetics and pharmacodynamics after change in basal insulin infusion rate

Background

The use of insulin pumps is rapidly increasing and new, technologically more advanced pumps are continuously being developed. It is of interest to assess the clinical relevance of the many technical features of these pumps, e.g., the effect on pharmacokinetics and pharmacodynamics with change in infusion rate.

Method

The aim of this study was to explore the sequence of pharmacokinetic and pharmacodynamic changes after dose doubling of the basal insulin infusion rate with subcutaneous bolus insulin injections once an hour, continuous subcutaneous insulin infusion, and continuous intravenous insulin infusion. Ten type 1 diabetes mellitus patients were included. The insulin doses were calculated based on the habitual insulin doses. The study was designed as an open-labeled, single-center, randomized, crossover exploratory trial.

Results

Dose doubling of the basal insulin infusion rate with the three different administration protocols did not result in any clinically relevant differences in the time courses of the pharmacokinetic and pharmacodynamic parameters. With all three administration protocols, we observed a time interval of more than 6 hours before a new steady state of insulin was achieved.

Conclusions

Our results indicate that frequent changes in basal subcutaneous insulin infusion rates are not of significant clinical relevance on a 24-hour basis. Regarding technological features of subcutaneous insulin pumps, no discernable advantages of increasing pump stroke frequency were found. This indicates that pump stroke frequency sophistication might not be of clinical relevance in pumps used for basal subcutaneous insulin infusion.     

Hyperhomocysteinemia,methylenetetrahydrofolate reductase c.677C>T polymorphism and risk of cancer: Cross‐sectional and prospective studies and meta‐analyses of 75,000 cases and 93,000 controls

Global DNA hypomethylation associates with development of cancer. DNA hypomethylation also associates with hyperhomocysteinemia and MTHFR c.677C>T homozygosity, both of which may associate with increased risk of cancer. We tested the putative association of hyperhomocysteinemia with cancer and the association of the MTHFR c.677TC>T variant with hyperhomocysteinemia and with cancer. We performed a cross‐sectional study of 5,949 Danish general population adults, a prospective study of 9,235 Danish general population adults with up to 60 years of registry surveillance, and meta‐analyses of 231 studies including 74,671 cases and 93,344 controls. Cross‐sectionally, plasma homocysteine levels were 12.9 and 11.6 μmol/L in those with and without cancer (p < 0.0001). However, homocysteine levels increased with age and age‐adjusted odds ratio for any cancer in those with homocysteine levels >12.4 versus < 9.4 μmol/L did not differ from 1.0. In cancer‐free participants, plasma homocysteine levels were 14.7 and 11.7 μmol/L in MTHFR c.677C>T homozygtes and noncarriers (p < 0.0001). Prospectively, hazard ratios for any cancer and for cancer subtypes in MTHFR c.677C>T homozygotes versus noncarriers did not differ from 1.0. However, in meta‐analyses odds ratio for MTHFR c.677C>T homozygotes versus noncarriers were 1.07 (95% CI: 1.01–1.12) for any cancer, 1.77 (1.17–2.68) for esophagus cancer, 1.40 (1.19–1.66) for gastric cancer and 0.85 (0.77–0.94) for colorectal cancer. Increased plasma homocysteine levels are not associated with an increased age‐adjusted risk of any cancer. However, MTHFR c.677C>T homozygosity with lifelong hyperhomocysteinemia and hence hypomethylation associate with increased risk of esophagus and gastric cancer, and with decreased risk of colorectal cancer.