•Simple electrochemical sensor for caffeine, superior to more complex sensor platforms.•Electrode modification strategies and analysis medium optimised.•Sensor based on bare or Nafion-modified glassy ...carbon gives best results.•Successful interference-free application to beverages and drugs.
A simple, economic, highly sensitive and highly selective method for the detection of caffeine has been developed at bare and Nafion-modified glassy carbon electrodes (GCE). The electrochemical behaviour of caffeine was examined in electrolyte solutions of phosphate buffer saline, sodium perchlorate, and in choline chloride plus oxalic acid, using analytical determinations by fixed potential amperometry, phosphate buffer saline being the best. Modifications of the GCE surface with poly(3,4-ethylenedioxythiophene) (PEDOT), Nafion, and multi-walled carbon nanotubes were tested in order to evaluate possible sensor performance enhancements, Nafion giving the most satisfactory results. The effect of interfering compounds usually found in samples containing caffeine was examined at GCE without and with Nafion coating, to exclude interferences, and the sensors were successfully applied to determine the caffeine content in commercial beverages and drugs.
Sun-related physiological disorders such as sun damage on apples (
Borkh) are caused by cumulative photooxidative and heat stress during their growing season triggering morphological, physiological, ...and biochemical changes in fruit tissues not only while it is on the tree but also after it has been harvested. The objective of the work was to establish the interaction of auxin (indole-3-acetic acid; IAA), abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), and ethylene (ET) and its precursor ACC (free and conjugated, MACC) during development of sun-injury-related disorders pre- and post-harvest on apples. Peel tissue was extracted from fruit growing under different sun exposures (Non-exposed, NE; Exposed, EX) and with sun injury symptoms (Moderate, Mod). Sampling was carried out every 15 days from 75 days after full bloom (DAFB) until 120 days post-harvest in cold storage (1°C, > 90%RH). Concentrations of IAA, ABA, JA, SA, were determined using UHPLC mass spectrometry, and ET and ACC (free and conjugated MACC) using gas chromatography. IAA was found not to be related directly to sun injury development, but it decreased 60% in sun exposed tissue, and during fruit development. ABA, JA, SA, and ethylene concentrations were significantly higher (
≤ 0.05) in Mod tissue, but their concentration, except for ethylene, were not affected by sun exposure. ACC and MACC concentrations increased until 105 DAFB in all sun exposure categories. During post-harvest, ethylene climacteric peak was delayed on EX compared to Mod. ABA and SA concentrations remained stable throughout storage in both tissue. JA dramatically increased post-harvest in both EX and Mod tissue, and orchards, confirming its role in low temperature tolerance. The results suggest that ABA, JA, and SA together with ethylene are modulating some of the abiotic stress defense responses on sun-exposed fruit during photooxidative and heat stress on the tree.
ABSTRACT
Background
Latin America has a high prevalence of Helicobacter pylori in children that may lead to peptic ulcer disease and eventually gastric cancer in adulthood. Successful eradication is ...hindered by rising antimicrobial resistance. We summarize H. pylori resistance rates in Latin American children from 2008 to 2023.
Material and Methods
Systematic review following PRISMA guidelines and National Heart, Lung, and Blood Institute checklist to assess risk of bias (PROSPERO CRD42024517108) that included original cross‐sectional observational studies reporting resistance to commonly used antibiotics in Latin American children and adolescents. We searched in PubMed, LILACS, and SciELO databases.
Results
Of 51 studies, 45 were excluded. The quality of the six analyzed studies (297 H. pylori‐positive samples) was satisfactory. Phenotypic methods (N = 3) reported higher resistance rates than genotypic studies (N = 3). Clarithromycin resistance ranged from 8.0% to 26.7% (6 studies; 297 samples), metronidazole from 1.9% to 40.2% (4 studies; 211 samples), amoxicillin from 0% to 10.4% (3 studies; 158 samples), tetracycline resistance was not detected (3 studies; 158 samples), and levofloxacin resistance was 2.8% (1 study; 36 samples).
Conclusion
Scarce Latin American studies on H. pylori resistance, along with methodological heterogeneity, hinder conclusive findings. Clarithromycin and metronidazole (first‐line drugs) resistance is worrisome, likely impacting lower eradication rates. Urgent systematic surveillance or individual testing before treatment is necessary to enhance eradication.
In
, the aging process is not equivalent between sexes and worsens for females. To determine the beginning of detrimental features in females and the ways in which to improve them, we compared adult ...females (36 months old) and aged females (72 months old) treated with Andrographolide (ANDRO), the primary ingredient in
. Our behavioral data demonstrated that age does not affect recognition memory and preference for novel experiences, but ANDRO increases these at both ages. Sociability was also not affected by age; however, social recognition and long-term memory were lower in the aged females than adults but were restored with ANDRO. The synaptic physiology data from brain slices showed that adults have more basal synaptic efficiency than aged degus; however, ANDRO reduced basal activity in adults, while it increased long-term potentiation (LTP). Instead, ANDRO increased the basal synaptic activity and LTP in aged females. Age-dependent changes were also observed in synaptic proteins, where aged females have higher synaptotagmin (SYT) and lower postsynaptic density protein-95 (PSD95) levels than adults. ANDRO increased the N-methyl D-aspartate receptor subtype 2B (NR2B) at both ages and the PSD95 and Homer1 only in the aged. Thus, females exposed to long-term ANDRO administration show improved complex behaviors related to age-detrimental effects, modulating mechanisms of synaptic transmission, and proteins.
•Radial Flesh Browning (FB) development was associated with sphingolipids metabolism.•Glucocerebrosides and ceramides were found in apples at risk of FB development.•Ceramides may have a key role in ...early chilling stress events leading to radial FB.•Ceramides may be used for forensic identification of radial FB.
Flesh browning (FB) of ‘Cripps Pink’ apples can cause significant economic losses to apple producers worldwide. FB symptoms and etiology can vary for this cultivar. Specific metabolic fingerprint has the potential for identification and understanding of different disorders leading FB postharvest. Flesh tissue from fruit collected starting 150 days after full bloom, through harvest, then, until 7 months into cold storage were sampled for non-targeted metabolic analyses using gas and liquid chromatography coupled with mass spectrometry. Radial FB development was positively associated with sphingolipids metabolism. Elevated levels of multiple glucocerebrosides and ceramides were found in apples at risk for developing the disorder and with symptoms, while the concentrations of a different group of inter-related metabolites tentatively as sphingolipids increased in healthy tissue during storage. Based on previous reports in other plant and animal species, elevated sphingolipid concentrations may be associated with membrane lipid catabolism, cell apoptosis, and fruit senescence involved in FB symptom development.
Alzheimer's disease (AD) is the most common type of dementia. The onset and progression of this pathology are correlated with several changes in the brain, including the formation of extracellular ...aggregates of amyloid-beta (Aβ) peptide and the intracellular accumulation of hyperphosphorylated tau protein. In addition, dysregulated neuronal plasticity, synapse loss, and a reduction in cellular energy metabolism have also been described. Canonical Wnt signaling has also been shown to be downregulated in AD. Remarkably, we showed previously that the
inhibition of Wnt signaling accelerates the appearance of AD markers in transgenic (Tg) and wild-type (WT) mice. Additionally, we found that Wnt signaling stimulates energy metabolism, which is critical for the ability of Wnt to promote the recovery of cognitive function in AD. Therefore, we hypothesized that activation of canonical Wnt signaling in a presymptomatic transgenic animal model of AD would improve some symptoms. To explore the latter, we used a transgenic mouse model (J20 Tg) with mild AD phenotype expression (high levels of amyloid aggregates) and studied the effect of
(ANDRO), an activator of canonical Wnt signaling. We found that presymptomatic administration of ANDRO in J20 Tg mice prevented the reduction in cellular energy metabolism markers. Moreover, treated animals showed improvement in cognitive performance. At the synaptic level, J20 Tg animals showed severe deficiencies in presynaptic function as determined by electrophysiological parameters, all of which were completely restored to normal by ANDRO administration. Finally, an analysis of hippocampal synaptosomes by electron microscopy revealed that the length of synapses was restored with ANDRO treatment. Altogether, these data support the idea that the activation of canonical Wnt signaling during presymptomatic stages could represent an interesting pharmacological strategy to delay the onset of AD.
Abstract Background Fat embolism syndrome (FES) is a rare but potentially fatal complication of trauma or orthopedic surgery, which presents predominantly with pulmonary symptoms. Modern intensive ...care has improved the mortality rates, however diagnosis remains difficult, relying predominantly on a combination of a classic triad of symptoms and non-specific, but characteristic radiological features. The aim of this review is to describe the main clinical and imaging aspects of FES, ranging from pathophysiology to treatment with emphasis on pulmonary involvement. Methods We reviewed the currently published literature on the main characteristics of FES. Results In a hypoxic patient with recent trauma or orthopedic surgery, the presence of diffuse, well-demarcated ground glass opacities or ill-defined centrilobular nodules on computed tomography (CT) of the chest are suggestive of FES. Conclusions Combination of the classic clinical syndrome in the appropriate clinical setting, together with the characteristic imaging findings on chest CT, can help to achieve the correct diagnosis. Management remains predominantly supportive care, and the benefit of medical therapies such as corticosteroids and heparin remains unclear.
A new and simple-to-prepare hypoxanthine biosensor has been developed using xanthine oxidase (XOD) immobilised on carbon electrode surfaces. XOD was immobilised by glutaraldehyde cross-linking on ...carbon film (CF) electrodes and on carbon nanotube (CNT) modified CF (CNT/CF). A comparison of the performance of the two configurations was carried out by the current response using amperometry at fixed potential; the best characteristics being exhibited by XOD/CNT/CF modified electrodes. The effects of electrolyte pH and applied potential were evaluated, and a proposal is made for the enzyme mechanism of action involving competition between regeneration of flavin adenine dinucleotide and reduction of hydrogen peroxide. Under optimised conditions, the determination of hypoxanthine was carried out at −0.2 V vs. a saturated calomel electrode (SCE) with a detection limit of 0.75 μM on electrodes with CNT and at −0.3 V vs. SCE with a detection limit of 0.77 μM on electrodes without CNT. The applicability of the biosensor was verified by performing an interference study, reproducibility and stability were investigated, and hypoxanthine was successfully determined in sardine and shrimp samples.
•Sunscald is an important postharvest disorder on apples Granny Smith.•Two prediction model with Vis-NIR reflectance were developed for sunscald on apples.•Model A predicted sunscald 45 days in ...advance on apples without sunburn at harvest.•Model B predicted sunscald 30 days in advance on apples with mild sunburn at harvest.
Sunscald on apples (Malus domestica Borkh) is a physiological disorder that develops post-harvest in susceptible cultivars such as Granny Smith. Symptoms appear on the skin as dark brown areas over fruit sections that were sun exposed during its growth on the tree. Currently, there is no chemical control to prevent its appearance. The objective of this study was to develop a prediction model for this disorder using Vis/NIR reflectance. During 2013/14 and 2014/15 Granny Smith apples were harvest and classified according to their sun exposure in the field (shaded, sun-exposed) and sun injury symptom (mild, moderate, severe), and stored at 0–1 °C (> 90% RH) for 120 d. Every 15 d sunscald incidence was recorded, and spectral fingerprint taken using an optical portable spectrometer Vis/NIR (350–1100 nm). Multivariate analysis was performed using partial least squares discriminant analysis (PLS-R) and intervals PLS-DA (iPLS-DA) in order to develop calibration models and applied them to a prediction set. Two calibration models were developed. The first one (A; R2CV = 0.41) for fruit at harvest with no sun damage symptoms (shaded and sun-exposed, n = 161), which was able to predict the appearance of sunscald 45 d in advance. The spectral ranges responsible for discrimination (iPLS-DA) of fruit with (Class 1) and without (Class 0) sunscald postharvest were: 500–525 nm, 550–575 nm, 650–675 nm, 775–800 nm, 850–875 nm, and 925–950 nm. The second model (B; R2CV = 0.59) was developed for mild sun damaged fruit (n = 100), which predicted sunscald 30 d in advance. In this case, the spectral ranges responsible of discrimination were 500–525 nm, 650–675 nm, and 775–800 nm, related to pigments and structural properties of the tissue. The RMSEP for the independent fruit set validation models (n = 69) were 3-4-times higher than that of the calibration models, probably because biological variability. A greater number of independent fruit sets will be required to increase models’ robustness and prediction capability for the industry adoption.
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