Foldable detergents for membrane protein stability

Detergents are widely used for membrane protein structural study. Many recently developed detergents contain multiple tail and head groups, which are typically connected via a small and branched linker. Due to their inherent compact structures, with small inter-alkyl chain distances, these detergents form micelles with high alkyl chain density in the interiors, a feature favorably associated with membrane protein stability. A recent study on tandem triazine maltosides (TZM) revealed a distinct trend; despite possession of an apparently large inter-alkyl chain distance, the TZM-Es were highly effective at stabilizing membrane proteins. Thanks to the incorporation of a flexible spacer between the two triazine rings in the linker region, these detergents are prone to folding into a compact architecture in micellar environments instead of adopting an extended conformation. Detergent foldability represents a new concept of novel detergent design with significant potential for future detergent development.

Glyco-steroidal amphiphiles (GSAs) for membrane protein structural study

Integral membrane proteins pose considerable challenges to high resolution structural analysis. Maintaining membrane proteins in their native state during protein isolation is essential for structural study of these bio-macromolecules. Detergents are the most commonly used amphiphilic compounds for stabilizing membrane proteins in solution outside a lipid bilayer. We previously introduced a glyco-diosgenin (GDN) detergent that was shown to be highly effective at stabilizing a wide range of membrane proteins. This steroidal detergent has additionally gained attention due to its compatibility with membrane protein structure study via cryo-EM. However, synthetic inconvenience limits widespread use of GDN in membrane protein study. To improve its synthetic accessibility and to further enhance detergent efficacy for protein stabilization, we designed a new class of glyco-steroid-based detergents using three steroid units: cholestanol, cholesterol and diosgenin. These new detergents were efficiently prepared and showed marked efficacy for protein stabilization in evaluation with a few model membrane proteins including two G protein-coupled receptors. Some new agents were not only superior to a gold standard detergent, DDM, but were also more effective than the original GDN at preserving protein integrity long term. These agents represent valuable alternatives to GDN, and are likely to facilitate structural determination of challenging membrane proteins.

Orthopaedic metallic artefact reduction algorithm facilitates CT evaluation of the urinary tract after hip prosthesis

AIM

To examine the improvement in the visualisation of bladder and ureteric pathologies next to a hip prosthesis with metallic artefact reduction for orthopaedic implants (O-MAR).

MATERIALS AND METHODS

Thirty-four patients who underwent pelvic computed tomography (CT) for non-prosthesis-related causes were enrolled retrospectively. Portal venous phase scans were reconstructed both with standard iterative reconstruction (ITR) and with O-MAR. The density of the ureters and the bladder was measured at both sides in the plane of the prosthesis. A semi-quantitative score was also used to assess visibility. The R (version 3.4.1) package was used for statistical analysis.

RESULTS

The average (μ) density of the 41 prosthesis side ureters was significantly lower on ITR images (μ=-94.76±150.48 [±SD] HU) than on O-MAR images (μ=-13.40±36.37 HU; p<0.0004). The difference between the ITR and O-MAR (μ=-138.62±182.64 versus -35.55±40.21 HU; p<0.0003) was also significant at the prosthesis side of the bladder. The visibility of the prosthesis side ureters was improved: 53.7% was obscured on ITR series compared to 4.9% on O-MAR. The visibility score was also better across all levels (p<0.001) with O-MAR. In four cases (13%), the O-MAR images significantly changed the diagnosis: in two cases ureteric stones, in one case each a bladder stone and a bladder tumour were discovered.

CONCLUSIONS

O-MAR reconstruction of CT images significantly improves the visibility of the urinary tract adjacent to metallic hip implants. Thus, O-MAR is essential for detecting ureteric and bladder pathologies in patients with a hip prosthesis.

P1711The association of multidisciplinary team approach with clinical outcomes in patients with acute myocardial infarction underwent veno-arterial extracorporeal membrane oxygenation

Background

Multidisciplinary team approach is necessary for the management of critically-ill patients. However, limited data are available on the impact of specialized extracorporeal membrane oxygenation (ECMO) team on clinical outcomes in patients with acute myocardial infarction (AMI) complicated by cardiogenic shock.

Objectives

This study aimed to identify whether specialized ECMO team is associated with improved in-hospital mortality in AMI patients underwent venoarterial ECMO.

Methods

A total of 255 AMI patients underwent venoarterial ECMO from May 2004 to July 2018 were enrolled. In January 2014, multidisciplinary ECMO team was founded at our institution. Eligible patients were classified into pre-ECMO team group (n=131) and post-ECMO team group (n=124). The primary outcome was in-hospital mortality.

Results

In-hospital mortality (54.2% vs. 33.9%, p=0.002) and cardiac intensive care unit mortality (45.0% vs. 25.0%, p=0.001) were significantly lower after the implantation of multidisciplinary ECMO team (pre ECMO team vs. post-ECMO team). On binary logistic regression model, the multidisciplinary ECMO team approach was associated with lower risk of in-hospital mortality (odds ratio 0.36, 95% confidence interval 0.19–0.67, p=0.001). Incidence of all-cause mortality (58.3% vs. 35.2%, p<0.001) and rehospitalization due to heart failure (28.2% vs. 6.4%, p=0.001) at 6-months follow-up were also significantly lower in the post-ECMO team group than in the pre-ECMO team group.

Clinical outcomes Variables Total (N=255) Pre-ECMO team (N=131) Post-ECMO team (N=124) P value In-hospital mortality 113 (44.3) 71 (54.2) 42 (33.9) 0.002 Cardiovascular death 90 (35.3) 59 (45.0) 31 (25.0) 0.001 Noncardiovascular death 23 (9.0) 12 (9.2) 11 (8.9) >0.99 Cardiac intensive care unit mortality 106 (41.6) 68 (51.9) 38 (30.6) 0.001 Successful weaning of ECMO 169 (66.3) 75 (57.3) 94 (75.8) 0.002 Data are presented as n (%). Abbreviations: ECMO, extracorporeal membrane oxygenation.

Incidence of death, readmission for HF

Conclusions

The multidisciplinary ECMO team approach was associated with improved clinical outcomes in AMI patients complicated by cardiogenic shock. Our data support that specialized ECMO team is indispensable to improve outcomes in patients with AMI with refractory cardiogenic shock.

Altered neural circuit for working memory before and after symptom provocation in patients with obsessive-compulsive disorder

OBJECTIVE

The authors compared the neural circuits recruited for working memory (WM) in obsessive-compulsive disorder (OCD) patients both at a neutral state and at a symptom provoked state.

METHOD

Twelve OCD patients, and 12 age-, and sex-matched healthy subjects underwent [(15)O]H(2)O positron emission tomography (PET) scanning, while performing WM task. In the patients, the tasks were performed both in the neutral and in the symptom provoked states.

RESULTS

In the OCD patients, the right caudate and the right superior parietal cortex (rSPC) displayed activations for WM at the neutral state, while the right cingulate cortex and rSPC displayed activations for WM at the symptom provoked state. Path analysis revealed that the activity of the caudate and orbitofrontal cortex was altered according to the interaction between WM and symptom provocation.

CONCLUSION

The interaction between symptom provocation and WM occurring in the fronto-striatal system may hold the key to the neurobiology of OCD.

Similarity and disparity of obsessive-compulsive disorder and schizophrenia in MR volumetric abnormalities of the hippocampus-amygdala complex

OBJECTIVES

Given that obsessive-compulsive disorder (OCD) and schizophrenia may share clinical symptoms as well as functional brain abnormalities, this study was designed to clarify common and different morphological abnormalities in OCD and schizophrenia.

METHODS

Volumes of the hippocampus, the amygdala, and the thalamus were measured in three age and sex matched groups of 22 patients with OCD, 22 patients with schizophrenia, and 22 normal subjects using three dimensional magnetic resonance imaging. Volume tracing was performed manually on serial coronal slices with the references of sagittal or axial planes using internal landmarks.

RESULTS

Hippocampal volume was bilaterally reduced in both OCD and schizophrenic patients versus the normal controls. Left amygdala volume was significantly enlarged in patients with OCD but not in patients with schizophrenia versus the normal controls. The thalamus did not show any volumetric group differences.

CONCLUSIONS

Non-specific hippocampal reduction in both the OCD and schizophrenic groups is likely to link to a clinical overlap between the two illnesses, whereas the left amygdala enlargement observed only in the OCD patients seems to be suggestive of a unique role for the amygdala in the pathophysiology of OCD.

Brain glucose metabolic changes associated with neuropsychological improvements after 4 months of treatment in patients with obsessive-compulsive disorder

OBJECTIVE

The study was designed to elucidate regional brain metabolic changes according to a treatment and their relationship with neuropsychological performance changes in obsessive-compulsive disorder (OCD).

METHOD

Cerebral glucose metabolic rates were repeatedly measured before and after treatment in 10 patients with OCD using [18F]-2-fluoro-deoxyglucose positron emission tomography (PET). They were compared on a voxel-basis, and the correlations were counted between the regional metabolic changes and the degree to improvement on the neuropsychological assessments.

RESULTS

After treatment, the patients showed significant (P < 0.005, two-tailed) regional metabolic changes in multiple brain areas involving frontal-subcortical circuits and parietal-cerebellar networks. Especially, the metabolic changes of the putamen, the cerebellum, and the hippocampus were significantly correlated with the improvement of the immediate- and delayed-recall scores of the Rey-Osterrieth Complex Figure Test (RCFT).

CONCLUSION

These results suggest a possibility that metabolic changes of frontal-subcortical and parietal-cerebellar circuit changes may underlie cognitive improvements in patients with OCD.

Length-dependent modulation of smooth muscle activation: effects of agonist, cytochalasin, and temperature

We tested the hypothesis that mechanical strain modulates agonist sensitivity of smooth muscle by measuring myosin phosphorylation and contractile force in bovine tracheal smooth muscle activated by various concentrations of the muscarinic receptor agonist carbachol and at various muscle lengths. Increasing carbachol concentration by 10,000-fold did not restore myosin phosphorylation levels at shorter muscle lengths to the level at optimal length (Lo). Maximum levels of myosin phosphorylation induced by carbachol at 0.6, 0.8, and 1.0 Lo were similar but became lower at <0.6 Lo. Cytochalasin D significantly attenuated carbachol-induced contraction by 54%. In addition, cytochalasin D treatment induced a parallel downward shift in the length-myosin phosphorylation relation. Lowering temperature from 37 to 23 degrees C did not significantly change the length dependencies of carbachol-induced active force and myosin phosphorylation. These results have led us to conclude that 1) agonist sensitivity and maximum level of activation (as measured by myosin phosphorylation) are targets of length-dependent modulation, 2) actin filaments involved in contraction and length-dependent modulation are distinct in sensitivity to cytochalasin D, and 3) length-dependent modulation is relatively temperature insensitive.

Right hemisphere abnormalities in major depression: quantitative electroencephalographic findings before and after treatment

The quantitative EEGs of drug-free depressed patients were analyzed and compared to age and sex-matched controls, using spectral analysis. In addition, QEEGs of depressed patients after clinical improvement resulting from 6 weeks of antidepressant treatment were also analyzed. The subjects were 20 patients suffering from major depression (DSM-III-R). Scores on the Hamilton Rating Scale for Depression (HRSD) of all patients showed a reduction of more than 50% at the end of the 6th week. The results show: (1) delta and theta bipolar absolute powers of the right hemisphere increased in drug-free depressed patients, compared to controls. (2) No changes in all bands of QEEG were found after clinical improvement resulting from 6 weeks of treatment. These results suggest that the right hemisphere plays an important role in major depression, and that a reduction in symptoms is not necessarily indicative of an improvement in underlying major depression.