A meta-analysis on first-trimester blood count parameters-is the neutrophil-to-lymphocyte ratio a potentially novel method for first-trimester preeclampsia screening?

Objective

Meta-analysis focusing on the role of first-trimester neutrophil-to-lymphocyte ratio (NLR) in the prediction of preeclampsia.

Data sources

PubMed, Scopus, Web of Science, Cochrane Library, and Embase databases were queried from inception up to December 31, 2022.

Study eligibility criteria

The study included all types of original research that was conducted in humans and values of NLR were measured during the first trimester, among patients who later developed preeclampsia, compared to the values of control groups.

Study appraisal and synthesis methods

Two reviewers independently performed data abstraction and quality appraisal, and disagreements were resolved by consensus and, if necessary, by the opinion of a third reviewer. During the analysis, PRISMA and MOOSE guidelines were followed. All statistical analyses were made with R.

Results

For the research on the predictive role of NLR values in the first trimester for preeclampsia, a total of 6 studies were selected for analysis, covering 2,469 patients. The meta-analysis revealed a 95% confidence interval (CI) for the effect size of 0.641 to 1.523, with a prediction interval of 0.027 to 2.137.

Conclusion

Based on the analysis, NLR is a promising biochemical marker for future pieces of research that try to find new screening methods for first-trimester preeclampsia. We encourage other researchers to examine NLR's predictive value combined with other markers in preeclampsia screening, this way being able to find new and affordable protocols for first-trimester preeclampsia screening.

Systematic review registration

identifier CRD42023392663.

Molecular imaging of bacterial outer membrane vesicles based on bacterial surface display

The important roles of bacterial outer membrane vesicles (OMVs) in various diseases and their emergence as a promising platform for vaccine development and targeted drug delivery necessitates the development of imaging techniques suitable for quantifying their biodistribution with high precision. To address this requirement, we aimed to develop an OMV specific radiolabeling technique for positron emission tomography (PET). A novel bacterial strain (E. coli BL21(DE3) ΔnlpI, ΔlpxM) was created for efficient OMV production, and OMVs were characterized using various methods. SpyCatcher was anchored to the OMV outer membrane using autotransporter-based surface display systems. Synthetic SpyTag-NODAGA conjugates were tested for OMV surface binding and 64Cu labeling efficiency. The final labeling protocol shows a radiochemical purity of 100% with a ~ 29% radiolabeling efficiency and excellent serum stability. The in vivo biodistribution of OMVs labeled with 64Cu was determined in mice using PET/MRI imaging which revealed that the biodistribution of radiolabeled OMVs in mice is characteristic of previously reported data with the highest organ uptakes corresponding to the liver and spleen 3, 6, and 12 h following intravenous administration. This novel method can serve as a basis for a general OMV radiolabeling scheme and could be used in vaccine- and drug-carrier development based on bioengineered OMVs.

Maternal age is highly associated with non-chromosomal congenital anomalies: Analysis of a population-based case-control database

OBJECTIVE

The role of maternal age in the development of non-chromosomal congenital anomalies (NCAs) is under debate. Therefore, the primary aim of this study was to identify the age groups at risk for NCAs. The secondary aim was to perform a detailed analysis of the relative frequency of various anomalies.

DESIGN

National population-based study.

SETTING

The Hungarian Case-Control Surveillance of Congenital Anomalies (CAs) between 1980 and 2009.

POPULATION OR SAMPLE

A cohort of 31 128 cases with confirmed NCAs was compared with Hungary's total of 2 808 345 live births.

METHODS

Clinicians prospectively reported cases after delivery. Data were analysed by non-linear logistic regression. Risk-increasing effect of young and advanced maternal age was determined by each NCA group.

MAIN OUTCOME MEASURES

These were the total number of NCAs: cleft lip and palate, circulatory, genital, musculoskeletal, digestive, urinary, eye, ear, face, and neck, nervous system, and respiratory system anomalies.

RESULTS

The occurrence of NCAs in our database was lowest between 23 and 32 years of maternal age at childbirth. The relative risk (RR) of any NCA was 1.2 (95% CI 1.17-1.23) and 1.15 (95% CI 1.11-1.19) in the very young and advanced age groups, respectively. The respective results for the circulatory system were RR = 1.07 (95% CI 1.01-1.13) and RR = 1.33 (95% CI 1.24-1.42); for cleft lip and palate RR = 1.09 (95% CI 1.01-1.19) and RR = 1.45 (95% CI 1.26-1.67); for genital organs RR = 1.15 (95% CI 1.08-1.22) and RR = 1.16 (95% CI 1.04-1.29); for the musculoskeletal system RR = 1.17 (95% CI 1.12-1.23) and RR = 1.29 (95% CI 1.14-1.44); and for the digestive system RR = 1.23 (95% CI 1.14-1.31) and RR = 1.16 (95% CI 1.04-1.29).

CONCLUSION

Very young and advanced maternal ages are associated with different types of NCAs. Therefore, screening protocols should be adjusted for these risk groups.

No Association between Gastrointestinal Rebleeding and DOAC Therapy Resumption: A Systematic Review and Meta-Analysis

BACKGROUND

There are recommendations for anticoagulation resumption after gastrointestinal bleeding (GIB), although data addressing this topic by direct oral anticoagulants (DOACs)-treated patients is lacking. We aim to determine the safety and efficacy of restarting DOACs after GIB.

METHODS

Studies that reported rebleeding, thromboembolic events, and mortality after restarting or withholding DOACs were selected. The systematic research was conducted in five databases (MEDLINE, EMBASE, CENTRAL, Web of Science, and Scopus). The random effect model was implemented to calculate the pooled odds ratio (OR). The ROBINS-I tool was used for risk of bias assessment, and the certainty of the evidence was evaluated with the GRADE approach.

RESULTS

Four retrospective cohort studies (1722 patients) were included in the meta-analysis. We did not find a significant increase in the risk of rebleeding in patients restarting DOACs after index GIB (OR = 1.12; 95% CI: 0.74-1.68). The outcomes of thromboembolic events and mortality data were not suitable for meta-analytic calculations. Single studies did not show statistically significant differences. Data quality assessment showed a serious overall risk of bias and very low quality of evidence (GRADE D).

CONCLUSION

DOAC resumption after a GIB episode may not elevate the risk of rebleeding. However, the need for high-quality randomized clinical trials is crucial.

The Predictive Role of Thyroid Hormone Levels for Early Diabetic Retinal Changes in Experimental Rat and Human Diabetes

Purpose

In diabetic subjects, early visual functional alterations such as color vision deficiencies (CVDs) are known to precede clinically apparent diabetic retinopathy. Prominent photoreceptor outer segment degeneration and an increase in the number of retinal dual cones (co-expressing S- and M-opsins simultaneously) have been described in diabetic rat models, suggesting a connection with the development of CVDs. As cone opsin expression is controlled by thyroid hormones, we investigated the diabetic retina in association with thyroid hormone alterations.

Methods

In rat models of type 1 and 2 diabetes, dual cones were labeled by immunohistochemistry, and their numbers were analyzed in relation to free triiodothyronine (fT3) and free thyroxine (fT4) levels. Quantification of dual cones was also performed in human postmortem retinas. Additionally, a cross-sectional case–control study was performed where thyroid hormone levels were measured and color vision was assessed with Lanthony desaturated D15 discs.

Results

A higher number of dual cones was detectable in diabetic rats, correlating with fT4 levels. Dual cones were also present in postmortem human retinas, with higher numbers in the three diabetic retinas. As expected, age was strongly associated with CVDs in human patients, and the presence of diabetes also increased the risk. However, the current study failed to detect any effect of thyroid hormones on the development of CVDs.

Conclusions

Our results point toward the involvement of thyroid homeostasis in the opsin expression changes in diabetic rats and human samples. The evaluation of the possible clinical consequences warrants further research.

Initial evidence of a 50% reduction of contrast media using digital variance angiography in endovascular carotid interventions

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Digital Variance Angiography (DVA) is a novel medical image processing method.

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DVA provides better image quality than Digital Subtraction Angiography (DSA).

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The quality reserve of DVA allows the reduction of contrast agents in angiography.

Purpose

In previous clinical studies Digital Variance Angiography (DVA) provided higher signal-to-noise ratio (SNR) and better image quality than Digital Subtraction Angiography (DSA). Our aim was to investigate whether this quality reserve of DVA provides an opportunity for the reduction of iodinated contrast media (ICM) in carotid X-ray angiography (CXA).

Method

Our prospective study enrolled 26 patients (67.0 ± 8.1 years) undergoing carotid percutaneous transluminal angioplasty. The SNR of DSA and DVA image pairs obtained by a standard (100 %, 6 mL ICM) or a low-dose (50 %, 3 mL ICM) protocol were compared. Visual evaluation of all images was performed by five specialists using a 5-grade rating scale. The quality of DSA₁₀₀ and DVA₅₀ videos was also compared.

Results

DVA provided more than two-fold SNR, the median SNR_DVA/SNR_DSA ratio was 2.06 (100 %) and 2.25 (50 %). In the visual evaluation, the DVA₁₀₀ score (3.73 ± 0.06) was significantly higher than the DSA₁₀₀ score (3.52 ± 0.07, Wilcoxon p < 0.001), and the DVA₅₀ score (3.64 ± 0.13) was also significantly higher than the DSA₅₀ score (3.01 ± 0.17, Wilcoxon p < 0.001). While the low-dose protocol significantly decreased the DSA score (Mann-Whitney p < 0.01, DSA₁₀₀ vs DSA₅₀), it had no effect on the DVA score (DVA₁₀₀ vs DVA₅₀). There was no statistical difference between the DSA₁₀₀ and DVA₅₀ scores. Evaluators preferred the diagnostic value of DVA₅₀ to DSA₁₀₀ videos in 61% of comparisons, the interrater agreement was 69 % (Fleiss’ kappa 0.35, p < 0.001)

Conclusions

Our data show that DVA allows a substantial (50 %) ICM reduction in CXA without affecting the quality and diagnostic value of angiograms.

Neutrophils produce proinflammatory or anti-inflammatory extracellular vesicles depending on the environmental conditions

Extracellular vesicles (EVs) are important elements of intercellular communication. A plethora of different, occasionally even opposite, physiologic and pathologic effects have been attributed to these vesicles in the last decade. A direct comparison of individual observations is however hampered by the significant differences in the way of elicitation, collection, handling, and storage of the investigated vesicles. In the current work, we carried out a careful comparative study on 3, previously characterized types of EVs produced by neutrophilic granulocytes. We investigated in parallel the modulation of multiple blood-related cells and functions by medium-sized vesicles. We show that EVs released from resting neutrophils exert anti-inflammatory action by reducing production of reactive oxygen species (ROS) and cytokine release from neutrophils. In contrast, vesicles generated upon encounter of neutrophils with opsonized particles rather promote proinflammatory processes as they increase production of ROS and cytokine secretion from neutrophils and activate endothelial cells. EVs released from apoptosing cells were mainly active in promoting coagulation. We thus propose that EVs are “custom made,” acquiring selective capacities depending on environmental factors prevailing at the time of their biogenesis.

Development and In Vivo Application of a Water-Soluble Anticancer Copper Ionophore System Using a Temperature-Sensitive Liposome Formulation

Liposomes containing copper and the copper ionophore neocuproine were prepared and characterized for in vitro and in vivo anticancer activity. Thermosensitive PEGylated liposomes were prepared with different molar ratios of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and hydrogenated soybean phosphatidylcholine (HSPC) in the presence of copper(II) ions. Optimal, temperature dependent drug release was obtained at 70:30 DPPC to HSPC weight ratio. Neocuproine (applied at 0.2 mol to 1 mol phospholipid) was encapsulated through a pH gradient while using unbuffered solution at pH 4.5 inside the liposomes, and 100 mM HEPES buffer pH 7.8 outside the liposomes. Copper ions were present in excess, yielding 0.5 mM copper-(neocuproine)₂ complex and 0.5 mM free copper. Pre-heating to 45 °C increased the toxicity of the heat-sensitive liposomes in short-term in vitro experiments, whereas at 72 h all investigated liposomes exhibited similar in vitro toxicity to the copper(II)-neocuproine complex (1:1 ratio). Thermosensitive liposomes were found to be more effective in reducing tumor growth in BALB/c mice engrafted with C26 cancer cells, regardless of the mild hyperthermic treatment. Copper uptake of the tumor was verified by PET/CT imaging following treatment with [⁶⁴Cu]Cu-neocuproine liposomes. Taken together, our results demonstrate the feasibility of targeting a copper nanotoxin that was encapsulated in thermosensitive liposomes containing an excess of copper.

Role of Mac-1 integrin in generation of extracellular vesicles with antibacterial capacity from neutrophilic granulocytes

Production of extracellular vesicles (EVs) involved in intercellular communication is a common capacity of most cell types. Upon encountering opsonized microorganisms, neutrophilic granulocytes release EVs that compromise bacterial growth. We carried out a systematic investigation of the involvement of potential opsonin receptors in EV-generation from human and murine neutrophils. Applying flow cytometric, proteomic and functional analysis as well as using genetically modified mice, we demonstrate that formation of antibacterial EVs depends upon stimulation of the multifunctional Mac-1 integrin complex, also called as complement receptor 3 (CR3), whereas activation of immunoglobulin binding Fc receptors or pattern recognition receptors alone or in combination is ineffective. Mac-1/CR3 stimulation and downstream tyrosine kinase signalling affect both the numbers, the cargo content and the antibacterial capacity of the produced vesicles. In contrast, Mac-1/CR3 signalling is not required for spontaneous EV formation, clearly indicating the existence of separate molecular pathways in EV biogenesis. We propose that EVs are “tailor-made” with different composition and functional properties depending on the environmental circumstances.

Radiomic detection of microscopic tumorous lesions in small animal liver SPECT imaging

BACKGROUND

Our aim was to present a new data analysis technique for the early detection of tumorous lesions using single-photon emission computed tomography (SPECT) imaging. Beyond standardized uptake value (SUV) and standardized uptake concentration (SUC), the skewness and kurtosis parameters of whole liver activity distribution histograms were examined in SPECT images to reveal the presence of tumorous cells.

METHODS

Four groups of mice were used in our experiment: a healthy control group, a group of obese mice with high body mass index, and two tumorous groups (primary liver cancer group with chemically induced hepatocellular carcinoma (HCC); metastatic liver tumor group-xenograft of human melanoma (HM)). For the SPECT measurements, ^99mTc-labeled aggregated albumin nanoparticles were administered intravenously 2 h before the liver SPECT scans (NanoSPECT/CT, Silver Upgrade, Mediso Ltd., Hungary) to image liver macrophages. Finally, SUV, SUC, skewness, and kurtosis of activity distributions were calculated from segmented whole liver volumes.

RESULTS

HCC animals showed moderate ^99mTc-albumin particle uptake with some visually identified cold spots indicating the presence of tumors. The visual detection of cold spots however was not a reliable marker of tumorous tissue in the metastatic group. The calculated SUV, SUC, and kurtosis parameters were not able to differentiate between the healthy and the tumorous groups. However, healthy and tumorous groups could be distinguished by comparing the skewness of the activity distribution.

CONCLUSION

Based on our results, ^99mTc-albumin nanoparticle injection followed by liver SPECT activity distribution skewness calculation is a suitable image analysis tool. This makes possible to effectively and quantitatively investigate liver macrophage inhomogeneity and identify invisible but present liver cold spot lesions. Skewness as a direct image-derived parameter is able to show altered tissue function even before the visual manifestation of liver tumor foci. The skewness of activity distribution might be related to an inhomogeneous distribution of macrophage cells as a consequence of microscopic tumor burden in the liver.

Evaluation of Brain Nuclear Medicine Imaging Tracers in a Murine Model of Sepsis-Associated Encephalopathy

Purpose

The purpose of this study was to evaluate a set of widely used nuclear medicine imaging agents as possible methods to study the early effects of systemic inflammation on the living brain in a mouse model of sepsis-associated encephalopathy (SAE). The lipopolysaccharide (LPS)-induced murine systemic inflammation model was selected as a model of SAE.

Procedures

C57BL/6 mice were used. A multimodal imaging protocol was carried out on each animal 4 h following the intravenous administration of LPS using the following tracers: [^99mTc][2,2-dimethyl-3-[(3E)-3-oxidoiminobutan-2-yl]azanidylpropyl]-[(3E)-3-hydroxyiminobutan-2-yl]azanide ([^99mTc]HMPAO) and ethyl-7-[¹²⁵I]iodo-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiazepine-3-carboxylate ([¹²⁵I]iomazenil) to measure brain perfusion and neuronal damage, respectively; 2-deoxy-2-[¹⁸F]fluoro-d-glucose ([¹⁸F]FDG) to measure cerebral glucose uptake. We assessed microglia activity on another group of mice using 2-[6-chloro-2-(4-[¹²⁵I]iodophenyl)-imidazo[1,2-a]pyridin-3-yl]-N-ethyl-N-methyl-acetamide ([¹²⁵I]CLINME). Radiotracer uptakes were measured in different brain regions and correlated. Microglia activity was also assessed using immunohistochemistry. Brain glutathione levels were measured to investigate oxidative stress.

Results

Significantly reduced perfusion values and significantly enhanced [¹⁸F]FDG and [¹²⁵I]CLINME uptake was measured in the LPS-treated group. Following perfusion compensation, enhanced [¹²⁵I]iomazenil uptake was measured in the LPS-treated group’s hippocampus and cerebellum. In this group, both [¹⁸F]FDG and [¹²⁵I]iomazenil uptake showed highly negative correlation to perfusion measured with ([^99mTc]HMPAO uptake in all brain regions. No significant differences were detected in brain glutathione levels between the groups. The CD45 and P2Y12 double-labeling immunohistochemistry showed widespread microglia activation in the LPS-treated group.

Conclusions

Our results suggest that [¹²⁵I]CLINME and [^99mTc]HMPAO SPECT can be used to detect microglia activation and brain hypoperfusion, respectively, in the early phase (4 h post injection) of systemic inflammation. We suspect that the enhancement of [¹⁸F]FDG and [¹²⁵I]iomazenil uptake in the LPS-treated group does not necessarily reflect neural hypermetabolism and the lack of neuronal damage. They are most likely caused by processes emerging during neuroinflammation, e.g., microglia activation and/or immune cell infiltration.

Electronic supplementary material

The online version of this article (10.1007/s11307-018-1201-3) contains supplementary material, which is available to authorized users.

Influence of barium sulfate X-ray imaging contrast material on properties of floating drug delivery tablets

The objective of the study was to reveal the influence of necessarily added barium sulfate (BaSO₄) X-ray contrast material on floating drug delivery tablets. Based on literature survey, a chosen floating tablet composition was determined containing HPMC and carbopol 943P as matrix polymers. One-factor factorial design with five levels was created for evaluation of BaSO₄ (X₁) effects on experimental parameters of tablets including: floating lag time, total floating time, swelling-, erosion-, dissolution-, release kinetics parameters and X-ray detected volume changes of tablets. Applied concentrations of BaSO₄ were between 0 and 20.0% resulting in remarkable alteration of experimental parameters related especially to flotation. Drastic deterioration of floating lag time and total floating time could be observed above 15.0% BaSO₄. Furthermore, BaSO₄ showed to increase the integrity of tablet matrix by reducing eroding properties. A novel evaluation of dissolutions from floating drug delivery systems was introduced, which could assess the quantity of drug dissolved from dosage form in floating state. In the cases of tablets containing 20.0% BaSO₄, only the 40% of total API amount could be dissolved in floating state. In vitro fine resolution X-ray CT imagings were performed to study the volume change and the voxel distributions as a function of HU attenuations by histogram analysis of the images. X-ray detected relative volume change results did not show significant difference between samples. After 24h, all tablets containing BaSO₄ could be segmented, which highlighted the fact that enough BaSO₄ remained in the tablets for their identification.

Production and in vivo imaging of (203)Pb as a surrogate isotope for in vivo (212)Pb internal absorbed dose studies

(212)Pb is a clinically relevant therapeutic alpha emitter isotope. A surrogate, (203)Pb, if prepared with sufficiently high specific activity could be used to estimate (212)Pb in vivo absorbed doses. An improved production procedure of (203)Pb with a simple, new separation method and high specific radioactivity for imaging is reported. We determined the in-vivo biodistribution of (203)Pb in mice by SPECT/CT. This highlights application possibilities of (203)Pb for further in vivo and clinical uses (radiolabeled (212)Pb-peptide co-injection, dosimetry calculation).

Radiomics-based differentiation of lung disease models generated by polluted air based on X-ray computed tomography data

BACKGROUND

Lung diseases (resulting from air pollution) require a widely accessible method for risk estimation and early diagnosis to ensure proper and responsive treatment. Radiomics-based fractal dimension analysis of X-ray computed tomography attenuation patterns in chest voxels of mice exposed to different air polluting agents was performed to model early stages of disease and establish differential diagnosis.

METHODS

To model different types of air pollution, BALBc/ByJ mouse groups were exposed to cigarette smoke combined with ozone, sulphur dioxide gas and a control group was established. Two weeks after exposure, the frequency distributions of image voxel attenuation data were evaluated. Specific cut-off ranges were defined to group voxels by attenuation. Cut-off ranges were binarized and their spatial pattern was associated with calculated fractal dimension, then abstracted by the fractal dimension -- cut-off range mathematical function. Nonparametric Kruskal-Wallis (KW) and Mann-Whitney post hoc (MWph) tests were used.

RESULTS

Each cut-off range versus fractal dimension function plot was found to contain two distinctive Gaussian curves. The ratios of the Gaussian curve parameters are considerably significant and are statistically distinguishable within the three exposure groups.

CONCLUSIONS

A new radiomics evaluation method was established based on analysis of the fractal dimension of chest X-ray computed tomography data segments. The specific attenuation patterns calculated utilizing our method may diagnose and monitor certain lung diseases, such as chronic obstructive pulmonary disease (COPD), asthma, tuberculosis or lung carcinomas.

A novel SPECT-based approach reveals early mechanisms of central and peripheral inflammation after cerebral ischemia

Inflammation that develops in the brain and peripheral organs after stroke contributes profoundly to poor outcome of patients. However, mechanisms through which inflammation impacts on brain injury and overall outcome are improperly understood, in part because the earliest inflammatory events after brain injury are not revealed by current imaging tools. Here, we show that single-photon emission computed tomography (NanoSPECT/CT Plus) allows visualization of blood brain barrier (BBB) injury after experimental stroke well before changes can be detected with magnetic resonance imaging (MRI). Early 99mTc-DTPA (diethylene triamine pentaacetic acid) signal changes predict infarct development and systemic inflammation preceding experimental stroke leads to very early perfusion deficits and increased BBB injury within 2 hours after the onset of ischemia. Acute brain injury also leads to peripheral inflammation and immunosuppression, which contribute to poor outcome of stroke patients. The SPECT imaging revealed early (within 2 hours) changes in perfusion, barrier function and inflammation in the lungs and the gut after experimental stroke, with good predictive value for the development of histopathologic changes at later time points. Collectively, visualization of early inflammatory changes after stroke could open new translational research avenues to elucidate the interactions between central and peripheral inflammation and to evaluate in vivo 'multi-system' effects of putative anti-inflammatory treatments.

Effect of storage on physical and functional properties of extracellular vesicles derived from neutrophilic granulocytes

Aim

To carry out a systematic study on the effect of different storage conditions on the number as well as the physical and functional properties of antibacterial extracellular vesicles (EVs) derived from human neutrophilic granulocytes.

Methods

Production of EVs with antibacterial properties was initiated by opsonized Zymosan A particles. The number of released fluorescent EVs was determined by flow cytometry following careful calibration. Physical properties and size of EVs were investigated by flow cytometry, dynamic light scattering and electron microscopy. Functional properties of EVs were tested by bacterial survival assay.

Results

Storage at +20°C or +4°C resulted in a significant decrease of EV number and antibacterial effect after 1 day. Storage at −20°C did not influence the EV number up to 28 days, but induced a shift in EV size and almost complete loss of antibacterial function by 28 days. Storage at −80°C had no significant effect either on EV number or size and allowed partial preservation of the antibacterial function up to 28 days. Snap-freezing did not improve the results, whereas the widely used cryoprotectants induced EV lysis.

Conclusion

Storage significantly alters both the physical and functional properties of EVs even if the number of EVs stays constant. If storage is needed, EVs should be kept at −80°C, preferably not longer than 7 days. For functional tests, freshly prepared EVs are recommended.

Longitudinal in vivo MR imaging of live earthworms

Earthworm (Oligochaeta, Lumbricidae) species are used widely in eco-toxicological tests especially with contaminated soils. These long-term tests are reliable, but a high sample size is needed. Magnetic resonance imaging (MRI) can produce fast, robust, sensitive, and longitudinal morphological results using a small sample size. Performing longitudinal in vivo examinations of earthworms using MRI requires the need for anesthetics to completely avoid earthworm's moving. Our goal was to develop a simple and non-invasive method to anesthetize earthworms for in vivo longitudinal imaging studies. We investigated a number of different anesthesia methods and found that propan-2-ol and its vapor was optimal. We used a commercial sequential nanoScan® PET/MRI system (Mediso Ltd, Hungary, Budapest) to explore feasibility of MR imaging in immobilized earthworms. It was possible to visualize via micro MRI the brain, gastrointestinal tract, seminal vesicles, calciferous gland (Morren gland), and main blood vessels of the circulatory system. Our findings show the possibilities to examine changes in morphology using MRI of certain organs using a reversible, long-term immobilization method.

Effect of storage on physical and functional properties of extracellular vesicles derived from neutrophilic granulocytes

AIM

To carry out a systematic study on the effect of different storage conditions on the number as well as the physical and functional properties of antibacterial extracellular vesicles (EVs) derived from human neutrophilic granulocytes.

METHODS

Production of EVs with antibacterial properties was initiated by opsonized Zymosan A particles. The number of released fluorescent EVs was determined by flow cytometry following careful calibration. Physical properties and size of EVs were investigated by flow cytometry, dynamic light scattering and electron microscopy. Functional properties of EVs were tested by bacterial survival assay.

RESULTS

Storage at +20°C or +4°C resulted in a significant decrease of EV number and antibacterial effect after 1 day. Storage at -20°C did not influence the EV number up to 28 days, but induced a shift in EV size and almost complete loss of antibacterial function by 28 days. Storage at -80°C had no significant effect either on EV number or size and allowed partial preservation of the antibacterial function up to 28 days. Snap-freezing did not improve the results, whereas the widely used cryoprotectants induced EV lysis.

CONCLUSION

Storage significantly alters both the physical and functional properties of EVs even if the number of EVs stays constant. If storage is needed, EVs should be kept at -80°C, preferably not longer than 7 days. For functional tests, freshly prepared EVs are recommended.