Two soluble glycosyltransferases glycosylate less efficiently in vivo than their membrane bound counterparts

Many Golgi glycosyltransferases are type II membrane proteins which are cleaved to produce soluble forms that are released from cells. Cho and Cummings recently reported that a soluble form of alpha1, 3- galactosyltransferase was comparable to its membrane bound counterpart in its ability to galactosylate newly synthesized glycoproteins (Cho,S.K. and Cummings,R.D. (1997) J. Biol. Chem., 272, 13622-13628). To test the generality of their findings, we compared the activities of the full length and soluble forms of two such glycosyltransferases, ss1,4 N-Acetylgalactosaminyltransferase (GM2/GD2/ GA2 synthase; GalNAcT) and beta galactoside alpha2,6 sialyltransferase (alpha2,6-ST; ST6Gal I), for production of their glycoconjugate products in vivo . Unlike the full length form of GalNAcT which produced ganglioside GM2 in transfected cells, soluble GalNAcT did not produce detectable GM2 in vivo even though it possessed in vitro GalNAcT activity comparable to that of full length GalNAcT. When compared with cells expressing full length alpha2,6-ST, cells expressing a soluble form of alpha2,6-ST contained 3-fold higher alpha2,6-ST mRNA levels and secreted 7-fold greater alpha2,6-ST activity as measured in vitro , but in striking contrast contained 2- to 4-fold less of the alpha2,6-linked sialic acid moiety in cellular glycoproteins in vivo . In summary these results suggest that unlike alpha1,3-galactosyltransferase the soluble forms of these two glycosyltransferases are less efficient at glycosylation of membrane proteins and lipids in vivo than their membrane bound counterparts.      

The Real World Mental Health Needs of Heart Failure Patients Are Not Reflected by the Depression Randomized Controlled Trial Evidence

Introduction

International depression screening guidelines in heart failure (HF) are partly based on depression treatment efficacy from randomized controlled trials (RCTs). Our aim was to test the external validity of depression RCT criteria in a sample of real-world HF patients.

Methods

HF patients admitted to 3 hospitals in South Australia were referred to a HF psychologist if not already receiving current psychiatric management by psychologist or psychiatrist elsewhere. Screening and referral protocol consisted of the following; (a). Patient Health Questionnaire ≥10; (b). Generalized Anxiety Disorder Questionnaire ≥7); (c). positive response to 1 item panic attack screener; (d). evidence of suicidality. Patients were evaluated against the most common RCT exclusion criteria personality disorder, high suicide risk, cognitive impairment, psychosis, alcohol or substance abuse or dependency, bi-polar depression.

Results

Total 81 HF patients were referred from 404 HF admissions, and 73 were assessed (age 60.6±13.4, 47.9% female). Nearly half (47%) met at least 1 RCT exclusion criterion, most commonly personality disorder (28.5%), alcohol/substance abuse (17.8%) and high suicide risk (11.0%). RCT ineligibility criteria was more frequent among patients with major depression (76.5% vs. 46.2%, p<.01) and dysthymia (26.5% vs. 7.7%, p = .03) but not significantly associated with anxiety disorders. RCT ineligible patients reported greater severity of depression (M = 16.6±5.0 vs. M = 12.9±7.2, p = .02) and were higher consumers of HF psychotherapy services (M = 11.5±4.7 vs. M = 8.5±4.8, p = .01).

Conclusion

In this real-world sample comparable in size to recent RCT intervention arms, patients with depression disorders presented with complex psychiatric needs including comorbid personality disorders, alcohol/substance use and suicide risk. These findings suggest external validity of depression screening and RCTs could serve as a basis for level A guideline recommendations in cardiovascular diseases.     

Classical conditioning and retention in normal and mutantDrosophila melanogaster

Summary By changing the conditioned discrimination paradigm of Quinn et al. (1974) from an instrumental procedure to a classical (Pavlovian) one, we have demonstrated strong learning in type flies. About 150 flies were sequestered in a closed chamber and trained by explosing them sequentially to two odors in air currents. Flies received twelve electric shock pulses in the presence of the first odor (CS+) but not in the presence of the second odor (CS–). To test for conditioned avoidance responses, flies were transported to a Tmaze choice point, between converging currents of the two odors. Typically, 95% of trained flies avoided the shock-associated odor (CS+).Acquisition of learning was a function of the number of shock pulses received during CS+ presentation and was asymptotic within one training cycle. Conditioned avoidance increased with increasing shock intensity or odor concentration and was very resistant to extinction. Learning was best when CS+ presentations overlap shock (delay conditioning) and then decreased with increasing CS-US interstimulus intervals. Shocking flies immediately before CS+ presentation (backward conditioning) produced no learning. Nonassociative control procedures (CS Alone, US Alone and Explicitly Unpaired) produced slight decreases in avoidance responses, but these affected both odors equally and did not alter our associative learning index (A).Memory in wild-type flies decayed gradually over the first seven hours after training and still was present 24 h later. The mutantsamnesiac, rutabaga anddunce showed appreciable learning acquisition, but their memories decayed very rapidly during the first 30 min. After this, the rates of decay slowed sharply; conditioned avoidance still was measurable at least three hours after training.Abbreviations OCT 3-octanol - MCH 4-methylcyclohexanol - C-S Canton-Special - CS conditioned stimulus - US unconditioned stimulus     

A Prospective Cohort Study of Absconsion Incidents in Forensic Psychiatric Settings: Can We Identify Those at High-Risk?

Background

Incidents of absconsion in forensic psychiatric units can have potentially serious consequences, yet surprisingly little is known about the characteristics of patients who abscond from these settings. The few previous studies conducted to date have employed retrospective designs, and no attempt has been made to develop an empirically-derived risk assessment scale. In this prospective study, we aimed to identify predictors of absconsion over a two-year period and investigate the feasibility of developing a brief risk assessment scale.

Methods

The study examined a representative sample of 135 patients treated in forensic medium- and low-secure wards. At baseline, demographic, clinical, treatment-related, and offending/behavioural factors were ascertained from electronic medical records and the treating teams. Incidents of absconsion (i.e., failure to return from leave, incidents of escape, and absconding whilst on escorted leave) were assessed at a two-year follow-up. Logistic regression analyses were used to determine the strongest predictors of absconsion which were then weighted according to their ability to discriminate absconders and non-absconders. The predictive utility of a brief risk assessment scale based on these weighted items was evaluated using receiver operator characteristics (ROC).

Results

During the two-year follow-up period, 27 patients (20%) absconded, accounting for 56 separate incidents. In multivariate analyses, four factors relating to offending and behaviour emerged as the strongest predictors of absconsion: history of sexual offending, previous absconsion, recent inpatient verbal aggression, and recent inpatient substance use. The weighted risk scale derived from these factors had moderate-to-good predictive accuracy (ROC area under the curve: 0.80; sensitivity: 067; specificity: 0.71), a high negative predictive value (0.91), but a low positive predictive value (0.34).

Conclusion

Potentially-targetable recent behaviours, such as inpatient verbal aggression and substance use, are strong predictors of absconsion in forensic settings; the absence of these factors may enable clinical teams to identify unnecessarily restricted low-risk individuals.     

Cell-based optimization of novel benzamides as potential antimalarial leads

Screening our in-house compound collection using a cell based Plasmodium falciparum proliferation assay we discovered a known pan-kinase inhibitor scaffold as a hit. Further optimization of this series led us to a novel benzamide scaffold which was devoid of human kinase activity while retaining its antiplasmodial activity. The evolution of this compound series leading to optimized candidates with good cellular potency against multiple strains as well as decent in vivo profile is described in this Letter.     

GBSX: a toolkit for experimental design and demultiplexing genotyping by sequencing experiments

Background

Massive parallel sequencing is a powerful tool for variant discovery and genotyping. To reduce costs, sequencing of restriction enzyme based reduced representation libraries can be utilized. This technology is generally referred to as Genotyping By Sequencing (GBS). To deal with GBS experimental design and initial processing specific bioinformatic tools are needed.

Results

GBSX is a package that assists in selecting the appropriate enzyme and the design of compatible in-line barcodes. Post sequencing, it performs optimized demultiplexing using these barcodes to create fastq files per barcode which can easily be plugged into existing variant analysis pipelines. Here we demonstrate the usability of the GBSX toolkit and demonstrate improved in-line barcode demultiplexing and trimming performance compared to existing tools.

Conclusions

GBSX provides an easy to use suite of tools for designing and demultiplexing of GBS experiments.     

Co-managing soil and plant pathogens: effects of organic amendments on soil fertility and fungal pathogen survival

Backgrounds and aims

Interactions between plants can be both positive and negative, denoting facilitation and competition. Although facilitative effects of having legume neighbours (focus on yield productivity) are well studied, a better mechanistic understanding of how legumes interact with non-legumes in terms of root distribution is needed. We tested the effects of neighbour identity, its spatial location, as well as the effects of plant order of arrival on above and belowground traits and root distribution.

Methods

We performed a rhizotron experiment (4 weeks duration) in which we grew maize alone, with only a legume, only another grass, or with both species and tracked roots of the plant species using green and red fluorescent markers.

Results

Maize grew differently when it had a neighbour, with reduced development when growing with wheat compared to alone. Growing with a legume generally equated to the same outcome as not having a neighbour. Roots grew towards the legume species and away from the wheat. Order of arrival affected aboveground traits to a certain extent, but its effects on maize roots were dependent on spatial location.

Conclusions

Our study provides evidence of facilitation, showing the importance of the identity of the neighbours, together with their spatial location, and how order of arrival can modulate the outcome of these initial interactions.

     

Exploring the Efficacy of Endoscopic Ventriculostomy for Hydrocephalus Treatment via a Multicompartmental Poroelastic Model of CSF Transport: A Computational Perspective

This study proposes the implementation of a Multiple-Network Poroelastic Theory (MPET) model coupled with finite-volume computational fluid dynamics for the purpose of studying, in detail, the effects of obstructing CSF transport within an anatomically accurate cerebral environment. The MPET representation allows the investigation of fluid transport between CSF, brain parenchyma and cerebral blood, in an integral and comprehensive manner. A key novelty in the model is the amalgamation of anatomically accurate choroid plexuses with their feeding arteries and a simple relationship relaxing the constraint of a unique permeability for the CSF compartment. This was done in order to account for the Aquaporin-4-mediated swelling characteristics. The aim of this varying permeability compartment was to bring to light a feedback mechanism that could counteract the effects of ventricular dilation and subsequent elevations of CSF pressure through the efflux of excess CSF into the blood system. This model is used to demonstrate the impact of aqueductal stenosis and fourth ventricle outlet obstruction (FVOO). The implications of treating such a clinical condition with the aid of endoscopic third (ETV) and endoscopic fourth (EFV) ventriculostomy are considered. We observed peak CSF velocities in the aqueduct of the order of 15.6 cm/s in the healthy case, 45.4 cm/s and 72.8 cm/s for the mild and severe cases respectively. The application of ETV reduced the aqueductal velocity to levels around 16–17 cm/s. Ventricular displacement, CSF pressure, wall shear stress (WSS) and pressure difference between lateral and fourth ventricles (ΔP) increased with applied stenosis, and subsequently dropped to nominal levels with the application of ETV. The greatest reversal of the effects of atresia come by opting for ETV rather than the more complicated procedure of EFV.