Lipoprotein lipase is active as a monomer

Lipoprotein lipase (LPL), the enzyme that hydrolyzes triglycerides in plasma lipoproteins, is assumed to be active only as a homodimer. In support of this idea, several groups have reported that the size of LPL, as measured by density gradient ultracentrifugation, is ∼110 kDa, twice the size of LPL monomers (∼55 kDa). Of note, however, in those studies the LPL had been incubated with heparin, a polyanionic substance that binds and stabilizes LPL. Here we revisited the assumption that LPL is active only as a homodimer. When freshly secreted human LPL (or purified preparations of LPL) was subjected to density gradient ultracentrifugation (in the absence of heparin), LPL mass and activity peaks exhibited the size expected of monomers (near the 66-kDa albumin standard). GPIHBP1-bound LPL also exhibited the size expected for a monomer. In the presence of heparin, LPL size increased, overlapping with a 97.2-kDa standard. We also used density gradient ultracentrifugation to characterize the LPL within the high-salt and low-salt peaks from a heparin-Sepharose column. The catalytically active LPL within the high-salt peak exhibited the size of monomers, whereas most of the inactive LPL in the low-salt peak was at the bottom of the tube (in aggregates). Consistent with those findings, the LPL in the low-salt peak, but not that in the high-salt peak, was easily detectable with single mAb sandwich ELISAs, in which LPL is captured and detected with the same antibody. We conclude that catalytically active LPL can exist in a monomeric state

Common, low-frequency, rare, and ultra-rare coding variants contribute to COVID-19 severity

The combined impact of common and rare exonic variants in COVID-19 host genetics is currently insufficiently understood. Here, common and rare variants from whole-exome sequencing data of about 4000 SARS-CoV-2-positive individuals were used to define an interpretable machine-learning model for predicting COVID-19 severity. First, variants were converted into separate sets of Boolean features, depending on the absence or the presence of variants in each gene. An ensemble of LASSO logistic regression models was used to identify the most informative Boolean features with respect to the genetic bases of severity. The Boolean features selected by these logistic models were combined into an Integrated PolyGenic Score that offers a synthetic and interpretable index for describing the contribution of host genetics in COVID-19 severity, as demonstrated through testing in several independent cohorts. Selected features belong to ultra-rare, rare, low-frequency, and common variants, including those in linkage disequilibrium with known GWAS loci. Noteworthily, around one quarter of the selected genes are sex-specific. Pathway analysis of the selected genes associated with COVID-19 severity reflected the multi-organ nature of the disease. The proposed model might provide useful information for developing diagnostics and therapeutics, while also being able to guide bedside disease management. © 2021, The Author(s)

Genetic mechanisms of critical illness in COVID-19.

Host-mediated lung inflammation is present1, and drives mortality2, in the critical illness caused by coronavirus disease 2019 (COVID-19). Host genetic variants associated with critical illness may identify mechanistic targets for therapeutic development3. Here we report the results of the GenOMICC (Genetics Of Mortality In Critical Care) genome-wide association study in 2,244 critically ill patients with COVID-19 from 208 UK intensive care units. We have identified and replicated the following new genome-wide significant associations: on chromosome 12q24.13 (rs10735079, P = 1.65 × 10-8) in a gene cluster that encodes antiviral restriction enzyme activators (OAS1, OAS2 and OAS3); on chromosome 19p13.2 (rs74956615, P = 2.3 × 10-8) near the gene that encodes tyrosine kinase 2 (TYK2); on chromosome 19p13.3 (rs2109069, P = 3.98 ×  10-12) within the gene that encodes dipeptidyl peptidase 9 (DPP9); and on chromosome 21q22.1 (rs2236757, P = 4.99 × 10-8) in the interferon receptor gene IFNAR2. We identified potential targets for repurposing of licensed medications: using Mendelian randomization, we found evidence that low expression of IFNAR2, or high expression of TYK2, are associated with life-threatening disease; and transcriptome-wide association in lung tissue revealed that high expression of the monocyte-macrophage chemotactic receptor CCR2 is associated with severe COVID-19. Our results identify robust genetic signals relating to key host antiviral defence mechanisms and mediators of inflammatory organ damage in COVID-19. Both mechanisms may be amenable to targeted treatment with existing drugs. However, large-scale randomized clinical trials will be essential before any change to clinical practice

Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans

Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in 25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16 regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP, while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium (LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region. Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the refined data for existing association signals, we estimate that these loci now explain ∼38.9% of the familial relative risk of PrCa, an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent signals within the same regio

A preclinical assessment of the non-heart beating donor pancreas for islet transplantation

The results of islet transplantation have been significantly improved in recent years following major advances made by the Edmonton group in Canada. These included transplanting fresh islets from more than one donor combined with a new less diabetogenic immunosuppressive protocol. Clinical islet transplant programs will be limited by the declining numbers of organ donors. Non-heart beating donors have been used to expand the renal donor pool, however the pancreas in particularly susceptible to warm ischaemia and may therefore not be suitable for islet transplantation.;The aim of this thesis was to evaluate the use of islets from non-heart beating donors in pre-clinical animal models. Different preservation methods were used including new and old preservation solutions along with the two-layer method (TLM) to attempt rodent pancreas resuscitation. However, even a short period of warm ischaemia led to poor islet yields and viability. A proportion of this work was to examine the use of ADP:ATP ratio as a potential viability test to estimate the degree of warm ischaemic damage.;Pulsatile machine perfusion has been a promising method for kidney preservation. A Waters RM3 perfusion machine was compared to both conventional cold storage and TLM for porcine pancreas preservation. Unfortunately, islet fragmentation and poor islet yields were a problem following machine perfusion suggesting that cold storage should remain the gold standard preservation method. In conclusion, the use of the non-heart beating donor pancreas for islet transplantation still remains a problem until more effective preservation methods are developed

Functionally selective signaling for morphine and fentanyl antinociception and tolerance mediated by the rat periaqueductal gray

Functionally selective signaling appears to contribute to the variability in mechanisms that underlie tolerance to the antinociceptive effects of opioids. The present study tested this hypothesis by examining the contribution of G protein-coupled receptor kinase (GRK)/Protein kinase C (PKC) and C-Jun N-terminal kinase (JNK) activation on both the expression and development of tolerance to morphine and fentanyl microinjected into the ventrolateral periaqueductal gray of the rat. Microinjection of morphine or fentanyl into the periaqueductal gray produced a dose-dependent increase in hot plate latency. Microinjection of the non-specific GRK/PKC inhibitor Ro 32-0432 into the periaqueductal gray to block mu-opioid receptor phosphorylation enhanced the antinociceptive effect of morphine but had no effect on fentanyl antinociception. Microinjection of the JNK inhibitor SP600125 had no effect on morphine or fentanyl antinociception, but blocked the expression of tolerance to repeated morphine microinjections. In contrast, a microinjection of Ro 32-0432 blocked the expression of fentanyl, but not morphine tolerance. Repeated microinjections of Ro 32-0432 blocked the development of morphine tolerance and inhibited fentanyl antinociception whether rats were tolerant or not. Repeated microinjections of SP600125 into the periaqueductal gray blocked the development of tolerance to both morphine and fentanyl microinjections. These data demonstrate that the signaling molecules that contribute to tolerance vary depending on the opioid and methodology used to assess tolerance (expression vs. development of tolerance). This signaling difference is especially clear for the expression of tolerance in which JNK contributes to morphine tolerance and GRK/PKC contributes to fentanyl tolerance

Clients with Physical Health Problems: For Whom Are Psychotherapies Effective? A Scoping Review

This is the protocol for a scoping review examining the frequency of reported demographic data for RCTs on obesity, cancer, and diabetes

The antinociceptive effects of microinjecting morphine or fentanyl into the ventrolateral PAG on Trial 1 were not altered by blocking activation of GRK/PKC or JNK.

<p>A) Microinjection of morphine produced an increase in hot plate latency compared to vehicle treated controls (F(3,32)  = 8.592, p = .0003) whether rats were pretreated with the GRK/PKC inhibitor Ro 32-0432 (400 ng/0.4 µl) or not (Bonferroni, t = 0.689, n.s.). B) Likewise, fentanyl antinociception (F(3,29)  = 7.661, p = .0008) was not altered by pretreatment with Ro 32-0432 (t = 1.882, n.s.). C) Microinjection of morphine produced an increase in hot plate latency compared to vehicle treated controls (F(3,29)  = 29.67, p = .0001) whether rats were pretreated with SP600125 (100 ng/0.4 µL) or not (t = 1.942, n.s.). D) Likewise, fentanyl antinociception (F(3,28)  = 3.194, p = .041) was not altered by SP600125 pretreatment (t = 0.008, n.s.).</p

Model of MOPr signaling showing that distinct molecules contribute to the development and expression of opioid tolerance.

<p>Tolerance could be caused by a change anywhere along the signaling pathway. If this change occurs at point C in the model, then repeated co-administration of an opioid with a drug that blocks signaling at points A, B, or C will prevent the development of tolerance. Once tolerance has developed, blocking signaling at points A or B will have no effect on the expression of tolerance because signaling at point C is already altered. However, a drug that blocks the enhanced signaling from points C, D, or E will block the expression of tolerance.</p