Lipid profiling of suction blister fluid: comparison of lipids in interstitial fluid and plasma

Hypercholesterolemia Is Associated With Dysregulation of Lipid Metabolism and Poor Prognosis in Primary Biliary Cholangitis

BACKGROUND & AIMS

Hypercholesterolemia is frequently diagnosed in patients with primary biliary cholangitis (PBC). However, its association with the prognosis and lipid metabolism is unknown. In this study, we aimed to investigate the prognostic value of baseline total cholesterol (TC) levels in PBC and characterized the associated lipid metabolism.

METHODS

Five hundred and thirty-one patients with PBC without prior cirrhosis-related complications were randomly divided into the derivation and validation cohorts at a ratio of 7:3. Complete clinical data were obtained and analyzed. The endpoints were defined as liver-related death, liver transplantation, and cirrhosis-related complications. Lipidomics was performed in 89 patients and 28 healthy controls.

RESULTS

Baseline TC was independently associated with poor liver-related outcomes, and adjusted C-statistics were 0.80 (95% confidence interval [CI]: 0.74-0.85) and 0.88 (95% CI: 0.78-0.91) in the derivation and validation cohorts, respectively. The predictive ability of TC for disease outcomes was stable over time and comparable with the Globe score. The 200 mg/dL cut-off optimally divided patients into low- and high-TC groups. A combination of TC and Globe score provided a more accurate stratification of patients into risk subgroups. Lipidomics indicated an up-regulation of lipid families in high-TC patients. Pathway analysis of 66 up-regulated lipids revealed the dysregulation of glycerophospholipid and sphingolipid metabolism in high-TC patients, which were associated with poor liver-related outcomes.

CONCLUSIONS

Our results indicate that patients with PBC having baseline TC levels above 200 mg/dL have unique lipidome characteristics and are at a higher risk of poor liver-related outcomes.

Microneedle Sensors for Point-of-Care Diagnostics

Point-of-care (POC) has the capacity to support low-cost, accurate and real-time actionable diagnostic data. Microneedle sensors have received considerable attention as an emerging technique to evolve blood-based diagnostics owing to their direct and painless access to a rich source of biomarkers from interstitial fluid. This review systematically summarizes the recent innovations in microneedle sensors with a particular focus on their utility in POC diagnostics and personalized medicine. The integration of various sensing techniques, mostly electrochemical and optical sensing, has been established in diverse architectures of "lab-on-a-microneedle" platforms. Microneedle sensors with tailored geometries, mechanical flexibility, and biocompatibility are constructed with a variety of materials and fabrication methods. Microneedles categorized into four types: metals, inorganics, polymers, and hydrogels, have been elaborated with state-of-the-art bioengineering strategies for minimally invasive, continuous, and multiplexed sensing. Microneedle sensors have been employed to detect a wide range of biomarkers from electrolytes, metabolites, polysaccharides, nucleic acids, proteins to drugs. Insightful perspectives are outlined from biofluid, microneedles, biosensors, POC devices, and theragnostic instruments, which depict a bright future of the upcoming personalized and intelligent health management.

Wearable Clinic: From Microneedle-Based Sensors to Next-Generation Healthcare Platforms

The rapid development of wearable biosensing calls for next-generation devices that allow continuous, real-time, and painless monitoring of health status along with responsive medical treatment. Microneedles have exhibited great potential for the direct access of dermal interstitial fluid (ISF) in a minimally invasive manner. Recent studies of microneedle-based devices have evolved from conventional off-line detection to multiplexed, wireless, and integrated sensing. In this review, the classification and fabrication techniques of microneedles are first introduced, and then the representative examples of microneedles for transdermal monitoring with different sensing modalities are summarized. State-of-the-art advances in therapeutic and closed-loop systems are presented to formulate guidelines for the development of next-generation microneedle-based healthcare platforms. The potential challenges and prospects are discussed to pave a new avenue toward pragmatic applications in the real world.

Cytokine patterns in the blister fluid and plasma of patients with fracture blisters

BACKGROUND

Fracture blister (FB) is a complication of fracture, which damages to the skin integrity and increases the risk of infection. Inflammation plays an important role in the formation and development of FBs, but its specific mechanism is still unclear. The aim of this study was to investigate the patterns and dynamic changes of inflammatory cytokines in fracture blister fluid (FBF) and plasma.

MATERIALS AND METHODS

FBF and plasma were collected simultaneously from patients with lower extremity fractures with FBs on the first and fifth day after blisters formation. 92 inflammation-related protein biomarkers were measured in plasma and FBF using Proximity Extension Assay (PEA). We analyzed the cytokine patterns and their dynamic changes in FBF and plasma. Cytokine patterns in plasma from FB patients, fracture without blister patients, and healthy subjects were also analyzed.

RESULT

The cytokine pattern in FBF and plasma of patients with FBs was different but 11 cytokines were significantly correlated in the two sample types. 23 cytokines were different in plasma across FB patients, fracture without blister patients and healthy subjects. In the analysis of plasma from FB patients and fracture without blister patients, 15 cytokines were significantly different and they may be potential risk factors for the occurrence of FBs. The FBF and plasma showed different cytokine patterns in the early and late stages, with 50 cytokines significantly changed in FBF and 20 cytokines in plasma.

CONCLUSION

The different cytokine patterns in plasma between FB patients and fracture without blisters patients may be the potential factors for the occurrence of blisters. The cytokine patterns in FBF and plasma showed a dynamic change from the inflammatory stage to the proliferative and repair stage, which indicates that FBs may have new clinical importance in addition to being a soft tissue injury.

Small volume rapid equilibrium dialysis (RED) measures effects of interstitial parameters on the protein-bound fraction of topical drugs

The importance of plasma protein binding in the early stages of drug development is well recognized. Free and bound drug fractions in plasma are routinely determined with well-established methods. However, for physiological fluids with a small accessible volume and low protein concentrations, such as dermal interstitial fluid (dISF) validated methods are currently missing. Due to the low protein concentration and highly dynamic processes in the dermis, protein binding data obtained from plasma samples may underestimate in-vivo efficacy. This study aimed to validate a small volume rapid equilibrium dialysis (RED) for low protein samples, as a tool to examine drug-protein binding directly in the biological fluid at the site of action. The sample volume required for RED was successfully downscaled to 50 µl and plasma protein binding values of the four model drugs were consistent with previous studies with an average recovery of 88 ± 8% which makes all tested drugs suitable for small volume RED. Inter- and intra-batch variability showed sufficient reproducibility across RED plates. Small volume RED was successfully applied to assess the effects of interstitial parameters, including the evaluation of the major binding protein and the effects of binding protein concentration, drug concentration, and pH on the protein-bound drug fraction using 2% HSA and/or diluted human plasma as a surrogate for dISF.

Fluid-based wearable sensors: a turning point in personalized healthcare

Nowadays, it has become very popular to develop wearable devices that can monitor biomarkers to analyze the health status of the human body more comprehensively and accurately. Wearable sensors, specially designed for home care services, show great promise with their ease of use, especially during pandemic periods. Scientists have conducted many innovative studies on new wearable sensors that can noninvasively and simultaneously monitor biochemical indicators in body fluids for disease prediction, diagnosis, and management. Using noninvasive electrochemical sensors, biomarkers can be detected in tears, saliva, perspiration, and skin interstitial fluid (ISF). In this review, biofluids used for noninvasive wearable sensor detection under four main headings, saliva, sweat, tears, and ISF-based wearable sensors, were examined in detail. This report analyzes nearly 50 recent articles from 2017 to 2023. Based on current research, this review also discusses the evolution of wearable sensors, potential implementation challenges, and future prospects.

ZFP750 affects the cutaneous barrier through regulating lipid metabolism

An essential function of the epidermis is to provide a physical barrier that prevents the loss of water. Essential mediators of this barrier function include ceramides, cholesterol, and very long chain fatty acids, and their alteration causes human pathologies, including psoriasis and atopic dermatitis. A frameshift mutation in the human ZNF750 gene, which encodes a zinc finger transcription factor, has been shown to cause a seborrhea-like dermatitis. Here, we show that genetic deletion of the mouse homolog ZFP750 results in loss of epidermal barrier function, which is associated with a substantial reduction of ceramides, nonpolar lipids. The alteration of epidermal lipid homeostasis is directly linked to the transcriptional activity of ZFP750. ZFP750 directly and/or indirectly regulates the expression of crucial enzymes primarily involved in the biosynthesis of ceramides. Overall, our study identifies the transcription factor ZFP750 as a master regulator epidermal homeostasis through lipid biosynthesis and thus contributing to our understanding of the pathogenesis of several human skin diseases.

Successful multimodal treatment of extreme hypertriglyceridemia in a juvenile diabetic dog

OBJECTIVE

To describe the therapeutic protocol used to normalize severe hypertriglyceridemia in a dog.

CASE SUMMARY

A 7-month-old, 1.2-kg female Pomeranian presented with acute polyuria, polydipsia, and ocular discoloration. Diagnoses included diabetic ketosis, severe hypertriglyceridemia (>225 mmol/L [>20,000 mg/dl]), lipemia retinalis, and bilateral uveitis. The triglyceride concentration was near normal within 2 days of initiating treatment with fenofibrate, regular insulin constant rate infusion (CRI), manual therapeutic plasma exchange (TPE), and a low-fat diet. All clinical signs resolved. The dog has had no relapse of hypertriglyceridemia at the time of writing the manuscript, 6 months later, with continued treatment of diabetes mellitus.

NEW OR UNIQUE INFORMATION PROVIDED

This is the first case report documenting the combination of fenofibrate, insulin CRI, and manual TPE for treatment of severe hyperlipidemia in a dog. Detailed protocols for manual TPE and a novel insulin CRI are provided. A discussion of multiple spurious biochemical and hematologic errors associated with the severe hypertriglyceridemia is also provided.

Prediction of subcutaneous drug absorption - characterization of subcutaneous interstitial fluids as a basis for developing biorelevant in vitro models

Unlike orally administered drugs, the absorption profile of subcutaneously injectable drugs in humans is difficult to predict from preclinical studies. Since the subcutaneous interstitial fluid (ISF) is the first fluid interacting with the administered formulation before the respective drug is absorbed, it could critically affect bioavailability. The aim of the present study was to gain a better understanding of the similarities and differences of ISF of different species. For this purpose, ISF was isolated from subcutaneous tissues of five preclinical animal species, i.e., mice, rats, minipig, landrace pig, non-human primates, and humans, using a centrifugation method, and characterized with respect to its major constituents and physicochemical properties. The results show trends between animal species, with ISF from non-human primates differing significantly from that of the other preclinical species for most parameters analyzed and showing similarities to ISF of human origin. Although from a statistical point of view it will be necessary to further increase the existing data sets, the presented data provide valuable information for the development of biorelevant in vitro models to predict the in vivo performance of subcutaneously administered formulations, as they provide fundamental information for the design of biorelevant ISF media for both preclinical species and humans.

Microneedle-based interstitial fluid extraction for drug analysis: Advances, challenges, and prospects

Similar to blood, interstitial fluid (ISF) contains exogenous drugs and biomarkers and may therefore substitute blood in drug analysis. However, current ISF extraction techniques require bulky instruments and are both time-consuming and complicated, which has inspired the development of viable alternatives such as those relying on skin or tissue puncturing with microneedles. Currently, microneedles are widely employed for transdermal drug delivery and have been successfully used for ISF extraction by different mechanisms to facilitate subsequent analysis. The integration of microneedles with sensors enables in situ ISF analysis and specific compound monitoring, while the integration of monitoring and delivery functions in wearable devices allows real-time dose modification. Herein, we review the progress in drug analysis based on microneedle-assisted ISF extraction and discuss the related future opportunities and challenges.

Optimization of the Sulfo-Phospho-Vanillin Assay for Total Lipid Normalization in Untargeted Quantitative Lipidomic LC-MS/MS Applications

Liquid chromatography (LC)-mass spectrometry (MS)/MS lipidomic normalization is generally performed by equalizing pre-extraction sample materials or via DNA or protein pre-quantitation methods, which have known measurement inaccuracies. We propose the use of the sulfo-phospho-vanillin assay (SPVA), a total lipid colorimetric analysis, as a pre-quantitation method to normalize lipids in lipidomic LC-MS/MS applications. The assay has been applied to a 300 μL well volume in a 96-well plate and tested using Avanti total lipid standards of porcine brain and E. coli. Assay parameters for lipid sample volume, sulfuric acid, vanillin/phosphoric acid, post-reaction incubation time, and wavelength are optimized for robust application to biologically sourced lipid samples. Standard test samples were prepared using three concentrations covering approximately 100 μg/mL range. The optimized assay yielded test sample errors less than 10%, indicating a precise and accurate assay performance. The test samples were then analyzed by LC-MS/MS and normalized using SPVA pre-quantitation and pseudo-mass normalization. The detected lipids showed smaller standard deviations and greater relative concentration differences compared to the pseudo-mass normalized lipids, showing promise as a normalization method.

Closing the loop for patients with Parkinson disease: where are we?

Although levodopa remains the most efficacious symptomatic therapy for Parkinson disease (PD), management of levodopa treatment during the advanced stages of the disease is extremely challenging. This difficulty is a result of levodopa's short half-life, a progressive narrowing of the therapeutic window, and major inter-patient and intra-patient variations in the dose-response relationship. Therefore, a suitable alternative to repeated oral administration of levodopa is being sought. Recent research efforts have focused on the development of novel levodopa delivery strategies and wearable physical sensors that track symptoms and disease progression. However, the need for methods to monitor the levels of levodopa present in the body in real time has been overlooked. Advances in chemical sensor technology mean that the development of wearable and mobile biosensors for continuous or frequent levodopa measurements is now possible. Such levodopa monitoring could help to deliver personalized and timely medication dosing to alleviate treatment-related fluctuations in the symptoms of PD. Therefore, with the aim of optimizing therapeutic management of PD and improving the quality of life of patients, we share our vision of a future closed-loop autonomous wearable 'sense-and-act' system. This system consists of a network of physical and chemical sensors coupled with a levodopa delivery device and is guided by effective big data fusion algorithms and machine learning methods.

Temperature acclimation of net photosynthesis and its underlying component processes in four tropical tree species

The effect of temperature change on leaf physiology has been extensively studied in temperate trees and to some extent in boreal and tropical tree species. While increased temperature typically stimulates leaf CO2 assimilation and tree growth in high-altitude ecosystems, tropical species are often negatively affected. These trees may operate close to their temperature optima and have a limited thermal acclimation capacity due to low seasonal and historical variation in temperature. To test this hypothesis, we studied the extent to which the temperature sensitivities of leaf photosynthesis and respiration acclimate to growth temperature in four common African tropical tree species. Tree seedlings native to different altitudes and therefore adapted to different growth temperatures were cultivated at three different temperatures in climate-controlled chambers. We estimated the acclimation capacity of the temperature sensitivities of light-saturated net photosynthesis, the maximum rates of Rubisco carboxylation (Vcmax) and thylakoid electron transport (J), and dark respiration. Leaf thylakoid membrane lipid composition, nitrogen content and leaf mass per area were also analyzed. Our results showed that photosynthesis in tropical tree species acclimated to higher growth temperatures, but that this was weakest in the species originating from the coolest climate. The temperature optimum of J acclimated significantly in three species and variation in J was linked to changes in the thylakoid membrane lipid composition. For Vcmax, there was only evidence of significant acclimation of optimal temperature in the lowest elevation species. Respiration acclimated to maintain homeostasis at growth temperature in all four species. Our results suggest that the lowest elevation species is better physiologically adapted to acclimate to high growth temperatures than the highest elevation species, indicating a potential shift in competitive balance and tree community composition to the disadvantage of montane tree species in a warmer world.

Reference materials for MS-based untargeted metabolomics and lipidomics: a review by the metabolomics quality assurance and quality control consortium (mQACC)

INTRODUCTION

The metabolomics quality assurance and quality control consortium (mQACC) is enabling the identification, development, prioritization, and promotion of suitable reference materials (RMs) to be used in quality assurance (QA) and quality control (QC) for untargeted metabolomics research.

OBJECTIVES

This review aims to highlight current RMs, and methodologies used within untargeted metabolomics and lipidomics communities to ensure standardization of results obtained from data analysis, interpretation and cross-study, and cross-laboratory comparisons. The essence of the aims is also applicable to other 'omics areas that generate high dimensional data.

RESULTS

The potential for game-changing biochemical discoveries through mass spectrometry-based (MS) untargeted metabolomics and lipidomics are predicated on the evolution of more confident qualitative (and eventually quantitative) results from research laboratories. RMs are thus critical QC tools to be able to assure standardization, comparability, repeatability and reproducibility for untargeted data analysis, interpretation, to compare data within and across studies and across multiple laboratories. Standard operating procedures (SOPs) that promote, describe and exemplify the use of RMs will also improve QC for the metabolomics and lipidomics communities.

CONCLUSIONS

The application of RMs described in this review may significantly improve data quality to support metabolomics and lipidomics research. The continued development and deployment of new RMs, together with interlaboratory studies and educational outreach and training, will further promote sound QA practices in the community.

Microneedle patches integrated with lateral flow cassettes for blood-free chronic kidney disease point-of-care testing during a pandemic

Chronic kidney disease (CKD) is the most neglected chronic disease affecting over 750 million persons in the world. Currently, many patients with cancers or other chronic diseases (i.e., CKD) struggle to receive clinical treatment or examination due to hospitals cancelling or delaying in the COVID-19 pandemic, which may increase the risk of death. Cystatin C (Cys C) has been proposed as a potential glomerular filtration rate (GFR) marker for the early detection of acute kidney injury and CKD. However, most traditional methods for Cys C detection are immunoassays using serum as a sample and are tedious to perform and economically burdensome. To diagnose the disease in the early stage and carry out daily management during the current pandemic, we developed an integration of hydrogel microneedle patch (HMNP) and lateral flow cassette (LFC) to rapidly detect Cys C in skin interstitial fluid (ISF) in 25 min for blood-free CKD management anytime and anywhere by the naked eye that can reduce the impact of an individual's quality of life and life expectancy. Conceivably, this strategy presents a wide scope in the application of numerous other diseases if corresponding analytes are available in skin ISF.

Handling the heat - photosynthetic thermal stress in tropical trees

Warming climate increases the risk for harmful leaf temperatures in terrestrial plants, causing heat stress and loss of productivity. The heat sensitivity may be particularly high in equatorial tropical tree species adapted to a thermally stable climate. Thermal thresholds of the photosynthetic system of sun-exposed leaves were investigated in three tropical montane tree species native to Rwanda with different growth and water use strategies (Harungana montana, Syzygium guineense and Entandrophragma exselsum). Measurements of chlorophyll fluorescence, leaf gas exchange, morphology, chemistry and temperature were made at three common gardens along an elevation/temperature gradient. Heat tolerance acclimated to maximum leaf temperature (T_leaf ) across the species. At the warmest sites, the thermal threshold for normal function of photosystem II was exceeded in the species with the highest T_leaf despite their higher heat tolerance. This was not the case in the species with the highest transpiration rates and lowest T_leaf . The results point to two differently effective strategies for managing thermal stress: tolerance through physiological adjustment of leaf osmolality and thylakoid membrane lipid composition, or avoidance through morphological adaptation and transpiratory cooling. More severe photosynthetic heat stress in low-transpiring montane climax species may result in a competitive disadvantage compared to high-transpiring pioneer species with more efficient leaf cooling.

Local burn wound environment versus systemic response: Comparison of proteins and metabolites

In this study, paired blood plasma (BP) and blister fluid (BF) samples from five paediatric burn patients were analysed using mass spectrometry to compare their protein and metabolite composition. The relative quantification of proteins was achieved through a label-free data independent acquisition mode. The relative quantification of metabolites was achieved using a Shimadzu Smart Metabolite Database gas chromatography mass spectrometry (GCMS) targeted assay. In total, 562 proteins and 141 individual metabolites were identified in the samples. There was 81% similarity in the proteins present in the BP and BF, with 50 and 54 unique proteins found in each sample type respectively. BF contained keratinocyte proliferation-related proteins and blood plasma contained abundant blood clotting proteins and apolipoproteins. BF contained more carbohydrates and less alpha-hydroxy acid metabolites than the BP. In this study, there were unique proteins and metabolites in BF and BP which were reflective of the local wound environment and systemic environments respectively. The results from this study demonstrate that the biomolecule content of BF is mostly the same as blood, but it also contains information specific to the local wound environment.

Prediction of subcutaneous drug absorption - do we have reliable data to design a simulated interstitial fluid?

For many years subcutaneous (SC) administration has represented the main route for delivering biopharmaceuticals. However, little information exists about the milieu in the subcutaneous tissue, especially about the properties/composition of the fluid present in this tissue, the interstitial fluid (ISF), which is one of the key elements for the drug release and absorption. Better knowledge on SC ISF composition, properties and dynamics may provide better insight into in vivo drug performance. In addition, a simulated SC ISF, which allows better prediction of in vivo absorption of drugs after subcutaneous administration based on in vitro release experiments, would help to improve formulation design, and reduce the number of animal studies and clinical trials required to obtain marketing authorization. To date, a universal medium for predicting drug solubility/release in the interstitial space does not exist. This review provides an overview of the currently available information on composition and physicochemical properties of SC ISF and critically discusses different isolation techniques in the context of information that could be gained from the isolated fluid. Moreover, it surveys current in vitro release media aiming to mimic SC ISF composition and highlights information gaps that need to be filled for designing a meaningful artificial SC ISF.

Lab under the Skin: Microneedle Based Wearable Devices

While the current smartwatches and cellphones can readily track mobility and vital signs, a new generation of wearable devices is rapidly developing to enable users to monitor their health parameters at the molecular level. Within this emerging class of wearables, microneedle-based transdermal sensors are in a prime position to play a key role in synergizing the significant advantages of dermal interstitial fluid (ISF) as a rich source of clinical indicators and painless skin pricking to allow the collection of real-time diagnostic information. While initial efforts of microneedle sensing focused on ISF extraction coupled with either on-chip analysis or off-chip instrumentation, the latest trend has been oriented toward assembling electrochemical biosensors on the tip of microneedles to allow direct continuous chemical measurements. In this context, significant advances have recently been made in exploiting microneedle-based devices for real-time monitoring of various metabolites, electrolytes, and therapeutics and toward the simultaneous multiplexed detection of key chemical markers; yet, there are several grand challenges that still exist. In this review, we outline current progress, recent trends, and new capabilities of microneedle-empowered sensors, along with the current unmet challenges and a future roadmap toward transforming the latest innovations in the field to commercial products.

Microneedle-based devices for point-of-care infectious disease diagnostics

Recent infectious disease outbreaks, such as COVID-19 and Ebola, have highlighted the need for rapid and accurate diagnosis to initiate treatment and curb transmission. Successful diagnostic strategies critically depend on the efficiency of biological sampling and timely analysis. However, current diagnostic techniques are invasive/intrusive and present a severe bottleneck by requiring specialist equipment and trained personnel. Moreover, centralised test facilities are poorly accessible and the requirement to travel may increase disease transmission. Self-administrable, point-of-care (PoC) microneedle diagnostic devices could provide a viable solution to these problems. These miniature needle arrays can detect biomarkers in/from the skin in a minimally invasive manner to provide (near-) real-time diagnosis. Few microneedle devices have been developed specifically for infectious disease diagnosis, though similar technologies are well established in other fields and generally adaptable for infectious disease diagnosis. These include microneedles for biofluid extraction, microneedle sensors and analyte-capturing microneedles, or combinations thereof. Analyte sampling/detection from both blood and dermal interstitial fluid is possible. These technologies are in their early stages of development for infectious disease diagnostics, and there is a vast scope for further development. In this review, we discuss the utility and future outlook of these microneedle technologies in infectious disease diagnosis.

Enhanced extraction of skin interstitial fluid using a 3D printed device enabling tilted microneedle penetration

Interstitial fluid (ISF) is a body fluid that fills, surrounds cells and contains various biomarkers, but it has been challenging to extract ISF in a reliable and sufficient amount with high speed. To address the issues, we developed the tilted microneedle ISF collecting system (TMICS) fabricated by 3D printing. In this system, the microneedle (MN) was inserted at 66° to the skin by TMICS so that the MN length could be extended within a safe range of skin penetration. Moreover, TMICS incorporating three MN patches created reliable ISF collecting conditions by penetrating the skin at consistent angle and force, 4.9 N. Due to the MN length increase and the patch number expansion, the surface area of the penetrated tissue was increased, thereby confirming that ISF extraction efficiency was improved. Skin ISF was collected into the paper reservoir on the patch, and the absorbed area was converted into a volume. ISF extraction from the rat skin in vivo by TMICS was well tolerated, and the 2.9 μL of ISF was obtained within 30 s. Therefore, TMICS is promising to apply in the diagnosis of multiple biomarkers in ISF with high speed and stability.

Sphingolipidomics of serum in extremely preterm infants: Association between low sphingosine-1-phosphate levels and severe retinopathy of prematurity

BACKGROUND

Extremely preterm infants are at risk of developing retinopathy of prematurity (ROP) that can cause impaired vision or blindness. Changes in blood lipids have been associated with ROP. This study aimed to monitor longitudinal changes in the serum sphingolipidome of extremely preterm infants and investigate the relationship to development of severe ROP.

METHODS

This is a prospective study that included 47 infants born <28 gestational weeks. Serum samples were collected from cord blood and at postnatal days 1, 7, 14, and 28, and at postmenstrual weeks (PMW) 32, 36, and 40. Serum sphingolipids and phosphatidylcholines were extracted and analyzed by LC-MS/MS. Associations between sphingolipid species and ROP were assessed using mixed models for repeated measures.

RESULTS

The serum concentration of all investigated lipid classes, including ceramide, mono- di- and trihexosylceramide, sphingomyelin, and phosphatidylcholine displayed distinct temporal patterns between birth and PMW40. There were also substantial changes in the lipid species composition within each class. Among the analyzed sphingolipid species, sphingosine-1-phosphate showed the strongest association with severe ROP, and this association was independent of gestational age at birth and weight standard deviation score change.

CONCLUSIONS

The serum phospho- and sphingolipidome undergoes significant remodeling during the first weeks of the preterm infant's life. Low postnatal levels of the signaling lipid sphingosine-1-phosphate are associated with the development of severe ROP.

Microneedle Arrays for Sampling and Sensing Skin Interstitial Fluid

Dermal interstitial fluid (ISF) is a novel source of biomarkers that can be considered as an alternative to blood sampling for disease diagnosis and treatment. Nevertheless, in vivo extraction and analysis of ISF are challenging. On the other hand, microneedle (MN) technology can address most of the challenges associated with dermal ISF extraction and is well suited for long-term, continuous ISF monitoring as well as in situ detection. In this review, we first briefly summarise the different dermal ISF collection methods and compare them with MN methods. Next, we elaborate on the design considerations and biocompatibility of MNs. Subsequently, the fabrication technologies of various MNs used for dermal ISF extraction, including solid MNs, hollow MNs, porous MNs, and hydrogel MNs, are thoroughly explained. In addition, different sensing mechanisms of ISF detection are discussed in detail. Subsequently, we identify the challenges and propose the possible solutions associated with ISF extraction. A detailed investigation is provided for the transport and sampling mechanism of ISF in vivo. Also, the current in vitro skin model integrated with the MN arrays is discussed. Finally, future directions to develop a point-of-care (POC) device to sample ISF are proposed.

Minimally Invasive Biospecimen Collection for Exposome Research in Children's Health

PURPOSE OF REVIEW

The advent of low-volume biosampling and novel biomarker matrices offers non- or minimally invasive approaches to sampling in children. These new technologies, combined with advancements in mass spectrometry that provide high sensitivity, robust measurements of low-concentration exposures, facilitate the application of untargeted metabolomics in children's exposome research. Here, we review emerging sampling technologies for alternative biomatrices-dried capillary blood, interstitial fluid, saliva, teeth, and hair-and highlight recent applications of these samplers to drive discovery in population-based exposure research.

RECENT FINDINGS

Biosampling and biomarker technologies demonstrate potential to directly measure exposures during key developmental time periods. While saliva is the most traditional of the reported biomatrices, each technology has key advantages and disadvantages. For example, hair and teeth provide retrospective analysis of past exposures, and dried capillary blood provides quantitative measurements of systemic exposures that can be more readily compared with traditional venous blood measurements. Importantly, all technologies can or have the potential to be used at home, increasing the convenience and parental support for children's biosampling. This review describes emerging sample collection technologies that hold promise for children's exposome studies. While applications in metabolomics are still limited, these novel matrices are poised to facilitate longitudinal exposome studies to discover key exposures and windows of susceptibility affecting children's health.

The Impact of Olive Oil Compounds on the Metabolic Reprogramming of Cutaneous Melanoma Cell Models

Cutaneous melanoma is the deadliest type of skin cancer, characterized by a high molecular and metabolic heterogeneity which contributes to therapy resistance. Despite advances in treatment, more efficient therapies are needed. Olive oil compounds have been described as having anti-cancer properties. Here, we clarified the cytotoxic potential of oleic acid, homovanillyl alcohol, and hydroxytyrosol on melanoma cells. Metabolic viability was determined 48 h post treatment of A375 and MNT1 cells. Metabolic gene expression was assessed by qRT-PCR and Mitogen-Activated Protein Kinase (MAPK) activation by Western blot. Hydroxytyrosol treatment (100 and 200 µM) significantly reduced A375 cell viability (p = 0.0249; p < 0.0001) which, based on the expression analysis performed, is more compatible with a predominant glycolytic profile and c-Jun N-terminal kinase (JNK) activation. By contrast, hydroxytyrosol had no effect on MNT1 cell viability, which demonstrates an enhanced oxidative metabolism and extracellular signal-regulated kinase (ERK) activation. This compound triggered cell detoxification and the use of alternative energy sources in A375 cells, inhibiting JNK and ERK pathways. Despite oleic acid and homovanillyl alcohol demonstrating no effect on melanoma cell viability, they influenced the MNT1 glycolytic rate and A375 detoxification mechanisms, respectively. Both compounds suppressed ERK activation in MNT1 cells. The distinct cell responses to olive oil compounds depend on the metabolic and molecular mechanisms preferentially activated. Hydroxytyrosol may have a cytotoxic potential in melanoma cells with predominant glycolytic metabolism and JNK activation.

Inflammatory Markers in Suction Blister Fluid: A Comparative Study Between Interstitial Fluid and Plasma

Background

Biomarker analysis allows for the detection and prediction of disease as well as health monitoring. The use of interstitial fluid (ISF) as a matrix for biomarkers has recently gained interest. This study aimed to compare levels of inflammatory markers in ISF from suction blister fluid (SBF) and plasma.

Methods

Plasma and SBF were collected from 18 healthy individuals. Samples were analyzed for 92 inflammation-related protein biomarkers by Proximity Extension Assay (PEA). Protein profiles in the two matrices were compared using traditional and multivariate statistics.

Results

Out of 92 targeted proteins, 70 were successfully quantified in both plasma and SBF. Overall, plasma and SBF displayed distinct protein profiles with up to 40-fold difference in abundance of specific proteins. The levels of 25 proteins were significantly correlated between plasma and SBF and several of these were recognized as potential markers to monitor health using ISF.

Conclusions

Skin ISF and plasma have unique protein profiles but many inflammatory markers are proportionally related between the matrices at the individual level. ISF is a promising biofluid for the monitoring of biomarkers in clinical studies and routine analyses.

Exploring the Lipidome: Current Lipid Extraction Techniques for Mass Spectrometry Analysis

In recent years, high-throughput lipid profiling has contributed to understand the biological, physiological and pathological roles of lipids in living organisms. Across all kingdoms of life, important cell and systemic processes are mediated by lipids including compartmentalization, signaling and energy homeostasis. Despite important advances in liquid chromatography and mass spectrometry, sample extraction procedures remain a bottleneck in lipidomic studies, since the wide structural diversity of lipids imposes a constrain in the type and amount of lipids extracted. Differences in extraction yield across lipid classes can induce a bias on down-stream analysis and outcomes. This review aims to summarize current lipid extraction techniques used for untargeted and targeted studies based on mass spectrometry. Considerations, applications, and limitations of these techniques are discussed when used to extract lipids in complex biological matrices, such as tissues, biofluids, foods, and microorganisms.