Biochemical and molecular approaches to understanding protein import into peroxisomes

Peroxisomes are eukaryotic organelles that perform diverse and variable functions. Although genetic studies in yeasts and mammals have identified approximately 20 genes (PEX genes) required for the biogenesis of this important organelle, biochemical studies of protein targeting and import have lagged behind and in many cases we have no idea of the function of the PEX gene products (peroxins). Using an import assay in vitro derived from sunflower cotyledon cells and recombinant proteins, we have obtained translocation intermediates on the peroxisome import pathway and are using cross-linking to identify interacting partners. We have also used antibodies raised against human PEX14 to inhibit the import of matrix proteins in this system. To obtain homologous antibodies for inhibition experiments, to immunoprecipitate cross-linked products and to enable us to study the import pathways of peroxins we have cloned and characterized plant orthologues of three PEX genes, PEX6, PEX10 and PEX14.

Impact of metformin on the all-cause mortality in diabetic patients hospitalized with acute heart failure

Introduction

Although the hypothesis that metformin is beneficial for diabetic patients with heart failure (HF) has been steadily raised, there have been no solid data on the efficacy of metformin in acute HF patients.

Purpose

We investigated the impact of metformin on all-cause mortality in hospitalized acute HF patients with type 2 diabetes.

Methods

The Korean Acute Heart Failure registry enrolled patients hospitalized for acute HF from 2011 to 2014. Among this cohort, we analyzed patients with diabetes. We investigated all-cause mortality at 1 year after discharge. Propensity score matching (1:1 matching) and Cox proportional hazard models were used to assess difference in all-cause mortality.

Results

The study analyzed 1,976 diabetic patients (median age 72 years, mean left ventricular ejection fraction (LVEF) 34%, 54.5% male). Among them, 712 (36%) patients were on metformin. After 1:1 propensity score matching, 1,424 patients (712 metformin users vs. 712 non-users) were analyzed. During the median follow-up period of 11 months, 146 (21%) metformin non-users died and 108 (15%) metformin users died. Kaplan-Meier curves showed a higher all-cause mortality rate in non-users than in metformin users (Log-rank P=0.0025). After adjustment for clinically relevant variables, metformin was associated with lower risk for all-cause mortality (HR 0.713, 95% CI 0.551–0.922, P=0.01). In subgroup analyses, metformin use was significantly associated with a lower all-cause mortality in higher eGFR group (≥60 ml/min/1.73 m2, HR 0.531, 95% CI 0.357–0.790, P=0.002), but not in lower eGFR group (<60 ml/min/1.73 m2, HR 0.905, 95% CI 0.643–1.275, P=0.569, P-for-interaction=0.033). There was no significant interaction of metformin use for all-cause mortality between the subgroups with LVEF ≤40% and LVEF >40% (P-for-interaction=0.906).

Conclusion

Metformin use was associated with a lower risk for 1-year all-cause mortality in diabetic acute HF patients, especially in high eGFR group.

Funding Acknowledgement

Type of funding sources: None.

Observation of strong oscillations of areal mass in an unsupported shock wave

An experimental study of hydrodynamic perturbation evolution in a strong unsupported shock wave, which is immediately followed by an expansion wave, is reported. A planar solid plastic target rippled on the front side is irradiated with a 350-450 ps long laser pulse. The perturbation evolution in the target is observed using face-on monochromatic x-ray radiography during and for up to 4 ns after the laser pulse. The theoretically predicted large oscillations of the areal mass in the target are observed for the first time. Multiple phase reversals of the areal mass modulation are detected.

National prevalence and socioeconomic factors associated with the acceptance of COVID-19 vaccines in South Korea: a large-scale representative study in 2021

OBJECTIVE

Among the global efforts toward preventing the COVID-19 pandemic, vaccines are a pivotal factor in ending the pandemic. Thus, through a large-scale population-based study, we investigated the individual-, social-, and family-associated factors affecting the acceptance of COVID-19 vaccines in South Korea.

PATIENTS AND METHODS

Data were obtained from a nationwide representative study (Korea Community Health) conducted in 2021. To determine the individual-, social-, and family-associated variables for COVID-19 vaccination acceptance, we investigated data from 225,319 individuals.

RESULTS

In the total sample (n=225,319), 184,529 COVID-19-vaccinated people and 40,790 non-vaccinated people were evaluated. The factors related to the acceptance of COVID-19 vaccination were significantly associated with the demographic factors, namely, older age group, female sex, and a history of influenza vaccination, as well as medical conditions such as diabetes, hypertension, and depression. Socioeconomic conditions influencing the acceptance of COVID-19 vaccination were significantly associated with low-income families and blue-collar workers. Health-related risk factors were high in the obese group. However, a noteworthy negative association was found between the acceptance of vaccination and smoking habits and alcohol consumption. Conversely, a positive association was observed between academic level and vaccination acceptance.

CONCLUSIONS

Our findings suggest that old age, female sex, a history of influenza vaccination, medical conditions, such as diabetes, hypertension, and depression, low-income families, blue-collar workers, and health-related risk factors, such as obesity, were associated with the acceptance of COVID-19 vaccination. Additionally, a high academic level, absence of smoking habits, and non-current alcohol use were positively associated with vaccine acceptance.

Multicenter Automated Central Vein Sign Detection Performs as Well as Manual Assessment for the Diagnosis of Multiple Sclerosis

BACKGROUND AND PURPOSE

The central vein sign (CVS) is a proposed diagnostic imaging biomarker for multiple sclerosis (MS). The proportion of white matter lesions exhibiting the CVS (CVS+) is higher in patients with MS compared with its radiologic mimics. Evaluation for CVS+ lesions in prior studies has been performed by manual rating, an approach that is time-consuming and has variable interrater reliability. Accurate automated methods would facilitate efficient assessment for CVS. The objective of this study was to compare the performance of an automated CVS detection method with manual rating for the diagnosis of MS.

MATERIALS AND METHODS

3T MRI was acquired in 86 participants undergoing evaluation for MS in a 9-site multicenter study. Participants presented with either typical or atypical clinical syndromes for MS. An automated CVS detection method was employed and compared with manual rating, including total CVS+ proportion and a simplified counting method in which experts visually identified up to 6 CVS+ lesions by using FLAIR* contrast (a voxelwise product of T2 FLAIR and postcontrast T2*-EPI).

RESULTS

Automated CVS processing was completed in 79 of 86 participants (91%), of whom 28 (35%) fulfilled the 2017 McDonald criteria at the time of imaging. The area under the receiver operating characteristic curve (AUC) for discrimination between participants with and without MS for the automated CVS approach was 0.78 (95% CI: [0.67,0.88]). This was not significantly different from simplified manual counting methods (select6*) (0.80 [0.69,0.91]) or manual assessment of total CVS+ proportion (0.89 [0.82,0.96]). In a sensitivity analysis excluding 11 participants whose MRI exhibited motion artifact, the AUC for the automated method was 0.81 [0.70,0.91], which was not statistically different from that for select6* (0.79 [0.68,0.92]) or manual assessment of total CVS+ proportion (0.89 [0.81,0.97]).

CONCLUSIONS

Automated CVS assessment was comparable to manual CVS scoring for differentiating patients with MS from those with other diagnoses. Large, prospective, multicenter studies utilizing automated methods and enrolling the breadth of disorders referred for suspicion of MS are needed to determine optimal approaches for clinical implementation of an automated CVS detection method.

Dye coupling of rabbit ciliary epithelial cells in vitro

PURPOSE

To examine the in vitro properties of gap junctions on the isolated rabbit ciliary epithelium.

METHODS

Intracellular potential was measured and lucifer yellow (5% in 1 M LiCl) was iontophoretically injected into a ciliary epithelial cell. Fixated tissue was examined with a laser confocal microscope.

RESULTS

Dye spread was observed throughout both layers (horizontally and vertically) of the ciliary epithelium adjacent to the injected cell that was more intensely labeled. Dye reflux did not occur at the site of microimpalement. Microiontophoretic dye injection in a bathing solution with a high Ca2+ (10 mM) or an acidic pH (6.3) completely inhibited cell-cell dye coupling in the rabbit ciliary epithelial cells.

CONCLUSIONS

Laser confocal microscopy of intracellularly injected lucifer yellow dye demonstrates the physiologic presence of gap junctions between both ciliary epithelial layers. Extracellular acidosis and high concentration of extracellular Ca2+ cause loss of cell-cell coupling in the rabbit ciliary epithelium.

GM-CSF is a marker of compartmentalised intrathecal inflammation in multiple sclerosis

BACKGROUND

Granulocyte-macrophage colony stimulating factor (GM-CSF) is a pro-inflammatory cytokine secreted by various immune cells. Several studies have demonstrated an expansion of GM-CSF producing T cells in the blood or CSF of people with MS (pwMS). However, whether this equates to greater concentrations of circulating cytokine remains unknown as quantification is difficult with traditional assays.

OBJECTIVE

To determine whether GM-CSF can be quantified and whether GM-CSF levels are elevated in pwMS.

METHODS

We employed Single Molecule Array (Simoa) to measure GM-CSF in both CSF and blood. We then investigated relationships between GM-CSF levels and measures of blood-CSF-barrier integrity.

RESULTS

GM-CSF was quantifiable in all samples and was significantly higher in the CSF of pwMS compared with controls. No association was found between CSF GM-CSF levels and Q-Albumin - a measure of blood-CSF-barrier integrity. CSF GM-CSF correlated with measures of intrathecal inflammation, and these relationships were greater in primary progressive MS compared with relapsing-remitting MS.

CONCLUSION

GM-CSF levels are elevated specifically in the CSF of pwMS. Our results suggest that elevated cytokine levels may reflect (at least partial) intrathecal production, as opposed to simple diffusion across a dysfunctional blood-CSF-barrier.

Elevated preoperative serum level of tumor markers CEA and CA 15–3 in breast cancer patients

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Background: Serological tumor markers: Cancer Antigen 15–3 (CA 15–3), Carcinoembryonic Antigen (CEA), have been investigated as useful markers for monitoring of response to treatment and for predicting outcome in breast cancer patients. Methods: A total of 820 breast cancer patients, treated over the period April 1999 through December 2003, had preoperative CA15–3 and CEA concentrations measured. The stage of the primary tumor ranged from 0 to IV. The median age of the patients was 47years (range 20–88 years old). The concentration of markers was investigated with regard to clinico-pathological parameters and patients outcome by both univariate and multivariate analysis. We determined the range of normality by the mean + 2 standard deviations of the markers distribution in populations of healthy females, who took an annual health screening program. Survival curves for disease free survival and death from disease were estimated by the method of Kaplan-Meier method and differences between groups in survival were tested using the log-rank test. All statistical analyses were carried out using SPSS statistics software (ver 10.5). Results: Among 820 patients, elevated preoperative level of CA15–3 and CEA was identified in 100 (12.2%) and 83 (10.1%) patients, respectively. Tumor size (>5cm), lymph node metastases (≥4), advanced stage (stage III and IV) were associated with significantly higher level of both preoperative CA15–3 and CEA. Elevated preoperative values of CA15–3 and CEA were associated with poor disease free survival (DFS, p=0.0019, p=0.0001, respectively) and distant relapse-free survival (DRFS, p=0.011, p=0.0034), but the level was marginal for overall survival (OS, p=0.0848, p=0.0895). By Cox’s multivariate analysis, younger age (<35 years), larger tumor size(>2cm), axillary node metastases, negative ER expression, elevated preoperative values of CA15–3 and CEA were independent prognostic factors for DFS and DRFS. Conclusions: High level of preoperative CA 15–3 and CEA might reflect a tumor burden, and is associated with advanced disease condition and disease-free survival. Measuring preoperative levels of CA 15–3 and CEA might be helpful for predicting the outcome and for planning the adjuvant therapy in breast cancer patients.

No significant financial relationships to disclose.