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This work presents the development and optimisation of an amperometric biosensor for determining aspartate aminotransferase (AST) activity in blood serum, using glutamate oxidase and platinum disc electrodes. AST is a key biomarker for diagnosing cardiovascular and liver diseases. The biosensor’s bioselective membrane composition and formation protocol and the working solution (aspartate 8 mM, α-ketoglutarate 2 mM, pyridoxal-5-phosphate 100 µM) were optimised. The sensor demonstrated high selectivity, stability (70% retention over 2 months at − 18  °C ), and sensitivity (2.37 nA min⁻ 1 per 10 U L⁻ 1 ), with a dynamic range of 0–500 U L⁻ 1 and a limit of detection of 1 U L⁻ 1 . Comparative analysis showed the calibration curve method outperforms the standard addition method for AST measurement in serum samples. Additionally, a reference spectrophotometric technique was adapted for AST level determination, showing a strong correlation ( r  = 0.989) with the biosensor results. This research offers a fast, affordable, and accurate tool for early check-ups of liver and heart conditions. The biosensor’s flexibility and ease of use make it suitable for further development into point-of-care testing and personalised healthcare techniques. Graphical Abstract

Diabetes mellitus, together with its complications, has been increasing in prevalence worldwide. Its complications include cardiovascular disease (e.g., myocardial infarction, stroke), neuropathy, nephropathy, and eye complications (e.g., glaucoma, cataracts, retinopathy, and macular edema). In patients with either type 1 or type 2 diabetes mellitus, diabetic retinopathy is the leading cause of visual impairment or blindness. It is characterized by progressive changes in the retinal microvasculature. The progression from nonproliferative diabetic retinopathy to a more advanced stage of moderate to severe nonproliferative diabetic retinopathy and proliferative diabetic retinopathy occurs very quickly after diagnosis of mild nonproliferative diabetic retinopathy. The etiology of diabetic retinopathy is unclear, and present treatments have limited effectiveness. Currently diabetic retinopathy can only be diagnosed by a trained specialist, which reduces the population that can be examined. A screening biomarker of diabetic retinopathy with high sensitivity and specificity would aid considerably in identifying those individuals in need of clinical assessment and treatment. The majority of the studies reviewed identified specific microRNAs in blood serum/plasma able to distinguish diabetic patients with retinopathy from those without retinopathy and for the progresion of the disease from nonproliferative diabetic retinopathy to proliferative diabetic retinopathy. In addition, certain microRNAs in vitreous humor were dysregulated in proliferative diabetic retinopathy compared to controls. A very high percentage of patients with diabetic retinopathy develop Alzheimer's disease. Thus, identifying diabetic retinopathy by measurement of suitable biomarkers would also enable better screening and treatment of those individuals at risk of Alzheimer's disease.

This study aimed to clarify the relationship between acute phase protein (APP) concentrations and serum Fe concentrations to determine whether serum iron (Fe) can be clinically applied as a substitute for APPs in cows. One hundred five Holstein–Friesian breed lactating dairy cows were enrolled in this study. Cows with inflammatory diseases were 16 subclinical, and 15 severe mastitis cows, in addition to 15 mild and 16 severe sole ulcer cows. The plasma haptoglobin (HPT), alpha-1 acid glycoprotein (AGP), SAA, serum Fe levels, and other biochemical parameters in the cows were measured. The two-sample t -tests and multiple logistic regression analysis were used to compare the control and inflammatory disease groups. ROC analysis was used to evaluate the ability to diagnose inflammation disease. From the results, the proposed diagnostic cutoff value for plasma SAA and serum Fe concentrations to identify dairy cows with inflammatory diseases based on analyses of ROC curves were set at > 3.65 mg/l and < 120.50 µg/dl, respectively. Therefore, instead of using expensive inflammatory markers to evaluate the inflammatory state at the first treatment day for inflammatory diseases in cow, it shows the useful for screening with serum Fe concentration that can be measured easily and inexpensively as alternative inflammatory biomarkers.

Being born small or large for gestational age (SGA and LGA, respectively), combined with suboptimal early postnatal outcomes, can entail future metabolic alterations. The exact mechanisms underlying such risks are not fully understood. Lipids are a highly diverse class of molecules that perform multiple structural and metabolic functions. Dysregulation of lipid metabolism underlies the onset and progression of many disorders leading to pathological states. The aim of this pilot study was to investigate the relationships between birth weight, early postnatal outcomes, and cord blood serum lipidomes. We performed a non-targeted lipidomics-based approach to ascertain differences in cord blood lipid species among SGA, LGA, and appropriate-for-GA (AGA) newborns. Moreover, we longitudinally assessed (at birth and at ages of 4 and 12 months) weight and length, body composition (DXA), and clinical parameters. We disclosed distinct cord blood lipidome patterns in SGA, LGA, and AGA newborns; target lipid species distinctly modulated in each SGA, AGA, and LGA individual were associated with parameters related to growth and glucose homeostasis. The distinct lipidome patterns observed in SGA, AGA, and LGA newborns may play a role in adipose tissue remodeling and future metabolic risks. Maternal dietary interventions may potentially provide long-term benefits for the metabolic health of the offspring.

In present work, the enzyme cholesterol oxidase (ChOx) was immobilized by Nafion® (Naf) on Pt,Ru–C nanocomposite and an ionic liquid (IL) – modified carbon paste electrode (CPE) in order to create cholesterol biosensor (Naf/ChOx/Pt,Ru–C/IL-CPE). The prepared working electrodes were characterized using scanning electron microscopy–energy-dispersive spectrometry, while their electrochemical performance was evaluated using electrochemical impedance spectroscopic, cyclic voltammetric, and amperometric techniques. Excellent synergism between IL 1-allyl-3-methylimidazolium dicyanamide ([AMIM][DCA]), Pt,Ru–C, and ChOx, as modifiers of CPE, offers the most pronounced analytical performance for improved cholesterol amperometric determination in phosphate buffer solution pH 7.50 at a working potential of 0.60 V. Under optimized experimental conditions, a linear relationship between oxidation current and cholesterol concentration was found for the range from 0.31 to 2.46 µM, with an estimated detection limit of 0.13 µM and relative standard deviation (RSD) below 5.5%. The optimized amperometric method in combination with the developed Naf/ChOx/Pt,Ru–C/IL-CPE biosensor showed good repeatability and high selectivity towards cholesterol biosensing. The proposed biosensor was successfully applied to determine free cholesterol in a human blood serum sample via its enzymatic reaction product hydrogen peroxide despite the presence of possible interferences. The percentage recovery ranged from 99.08 to 102.81%, while RSD was below 2.0% for the unspiked as well as the spiked human blood serum sample. The obtained results indicated excellent accuracy and precision of the method, concluding that the developed biosensor can be a promising alternative to existing commercial cholesterol tests used in medical practice. Graphical abstract

A highly sensitive square-wave adsorptive anodic stripping voltammetric method is described for the determination of ribavirin in its pharmaceutical formulations and human blood serum, utilizing a carbon paste electrode. The peak current was significantly enhanced due to the strong adsorptive properties of the drug at the electrode surface. The optimal procedural parameters were: frequency of 20 Hz, scan increment of 4 mV, pulse amplitude of 25 mV, and accumulation potential of –0.5 V versus Ag/AgCl/3 M KCl in Britton–Robinson buffer at pH 8.0. The described method was successfully applied for the assay of ribavirin in its pharmaceutical formulation (Ribavirin ® capsules, 200 mg ribavirin), with mean percentage recoveries of (98.3 ± 1.3)%. Furthermore, the method was successfully applied for the assay of ribavirin in spiked human blood serum without the necessity for sample pretreatment or time-consuming extraction prior to analysis. The mean percentage recovery of ribavirin in human blood serum was (98.6 ± 1.1)% ( n = 5), with a limit of detection of 1 × 10 –9 M (0.24 ng/mL). Due to this extremely low limit of detection, the proposed method can be applied in pharmacokinetic and pharmacodynamic studies of the drug.

There is a need for quick and reliable methods for rapid screening of drug-influenced drivers on the roadside by police. Because the window of detection in oral fluid is more similar to blood than to urine, this matrix should therefore be appropriate for screening procedures. The performance of the Rapid STAT® (Mavand Solution GmbH, Mössingen, Germany), DrugWipe5/5+® (Securetec Detektions-Systeme AG, Brunnthal, Germany) and Dräger DrugTest® 5000 (Draeger Safety AG & Co. KGaA, Luebeck, Germany) on-site oral fluid devices was evaluated with random oral fluid specimens from car drivers in North Rhine-Westphalia (Germany). Additionally, some drivers were checked using an on-site urine device (DrugScreen®, NAL von Minden, Regensburg, Germany). During a 11-month period, 1.212 drivers were tested. Both OF and urine on-site tests were compared to serum results. The following sensitivities were obtained by the oral fluid devices: THC 71% (DrugWipe®), 87% (Dräger), 91% (RapidSTAT); opiates 95% (Dräger), 100% (DrugWipe®, RapidSTAT®); amphetamine 84% (DrugTest® 5000), 90% (RapidSTAT®), 100% (DrugTest® 5000); methamphetamine 50% (DrugTest® 5000), 100% (RapidSTAT®); cocaine 76% (DrugTest® 5000), 100% (DrugWipe®, RapidSTAT®); methadone 33–63%, and benzodiazepines 0–33% (both with a low number of positives). THC specificity was especially low (29% [DrugWipe®] and 47% [DrugTest® 5000]) due to low cut-off concentrations. These data were similar to those obtained from the literature (e.g., DRUID project). The urine screening device showed a good sensitivity (THC 93%, opiate 94%, amphetamine 94%, methamphetamine 75% (low number of positives), cocaine 100%) and also an acceptable specificity (39%, 86%, 63%, 77%, 47%, respectively). Although oral fluid may be a useful matrix for on-site testing of drugged drivers, it is evident that oral fluid devices still show a lack of sensitivity (methamphetamine, benzodiazepines) and specificity (THC). Poor results for benzodiazepines may be explained by the small positive test number. Although the sensitivity for THC came out higher than compared to the literature, specificity is not yet satisfactory (only <90%). Furthermore, specificity was poor due to lowered cut-offs resulting in multiple false positive tests.

Migratory capabilities of adult human stem cells are vital for assuring endogenous tissue regeneration and stem cell-based clinical applications. Although human blood serum has been shown to be beneficial for cell migration and proliferation, little is known about its impact on the migratory behavior of cardiac stem cells and underlying signaling pathways. Within this study, we investigated the effects of human blood serum on primary human cardiac stem cells (hCSCs) from the adult heart auricle. On a technical level, we took advantage of a microfluidic cultivation platform, which allowed us to characterize cell morphologies and track migration of single hCSCs via live cell imaging over a period of up to 48 h. Our findings showed a significantly increased migration distance and speed of hCSCs after treatment with human serum compared to control. Exposure of blood serum-stimulated hCSCs to the p38 mitogen-activated protein kinase (p38-MAPK) inhibitor SB239063 resulted in significantly decreased migration. Moreover, we revealed increased phosphorylation of heat shock protein 27 (Hsp27) upon serum treatment, which was diminished by p38-MAPK-inhibition. In summary, we demonstrate human blood serum as a strong inducer of adult human cardiac stem cell migration dependent on p38-MAPK/Hsp27-signalling. Our findings further emphasize the great potential of microfluidic cultivation devices for assessing spatio-temporal migration dynamics of adult human stem cells on a single-cell level.

Mammalian plasma proteins play a key role in maintaining tissue fluid balance because they are retained within capillaries and thus create colloid osmotic pressure. Likewise, fish plasma contain a considerable concentration oligomeric proteins which likely serve a similar role. To elucidate the functions of these oligomeric proteins, we analyzed blood serum (BS) and interstitial fluid (IF) complexes in goldfish from the wild and under experimental conditions using 2D electrophoresis and matrix-assisted laser desorption/ionization (MALDI). We detected protein compounds with MWs ranging from 50 to 155 kDa, organized as oligomeric complexes. The protein compounds consisted of apolipoproteins АроА-I and Аро-14 which are homological to mammalian АроА-I and АроА-II, respectively. The 155-kDa and 50–125-kDa oligomer complexes were located very low-density lipoproteins (LDL) and high-density lipoproteins (HDL) areas on the BS/IF proteomic maps, respectively. The latter resembled mammalian HDL plasma particles by size and contained lipids, so we considered them as HDL particle populations. Investigation of the uniform dissociation/association mechanism for HDL and LDL oligomers in goldfish, from the wild and under critical salinity conditions, showed the “125/110 → 85/60 kDa” reorganization. This was associated with overcoming physiological stress during spawning and under critical salinity conditions. Opposite reorganization “85/60 → 125/110 kDa” was associated with restoration of metabolic processes after stress. The association/dissociation reorganizations promoted equilibration of BS and IF osmolarities in all fish groups. We discuss the connection of these reorganizations with total protein distribution across the capillary wall and salinity, as well as the role of oligomeric apolipoproteins as universal metabolic regulators.

This study was conducted to evaluate the effect of supplementation different levels of Clomiphene citrate to the diet of female quail on productive and some physiological traits. The experiment was conducted in a commercial farm from 2/3/2021 to 24/5/2021 (3 months). Females aged 50 weeks (160 females) were randomly distributed into four treatments, and each treatment included four replicates (10 birds for each replicate). The treatments were divided into a control group (T1; basic diet only), second treatment (T2; basic diet + 0.25 mg / female / day), third treatment (T3; basic diet + 0.50 mg / female / day, fourth treatment (T4; basic diet + 0.75 mg / female / day Clomiphene citrate). The results of the study indicated a significant improvement in favor of the addition treatments compared with the control treatment when calculating the average (%) of eggs production, the average of eggs weight (gm), the average of eggs mass (gm/female/day), and cumulative egg number (egg/female). As for the physiological characteristics, the results shown a high concentration of calcium and phosphorous in the blood serum within the additive treatments compared with the control  While there were no significant differences observed among treatments in total protein, albumin, globulin, and cholesterol. It could be conclude from this study that the addition of Clomiphene citrate to the diet improved the reproductive and physiological characteristics of female quail.