Search Results (116)

Soil organic carbon (SOC) pool plays an extremely important role in regulating the global carbon (C) cycle and climate change. Atmospheric nitrogen (N) and phosphorus (P) deposition caused by human activities has significant impacts on soil C sequestration potential of terrestrial ecosystem. To investigate the effects of N and P deposition on soil C sequestration and C-N coupling relationship in broad-leaved evergreen forests, a 6-year field nutrient regulation experiment was implemented in subtropical Castanopsis sclerophylla forests with four different N and P additions: N addition (100 kg N·hm⁻²·year⁻¹), N + P (100 kg N·hm⁻²·year⁻¹ + 50 kg P·hm⁻²·year⁻¹), P addition (50 kg P·hm⁻²·year⁻¹), and CK (0 kg N·hm⁻²·year⁻¹). The changes in the C and N contents and stable isotope distributions (δ¹³C and δ¹⁵N) of different soil organic fractions were examined. The results showed that the SOC and total nitrogen (STN) (p > 0.05) increased with N addition, while SOC significantly decreased with P addition (p < 0.05), and N + P treatment has low effect on SOC, STN (p > 0.05). By density grouping, it was found that N addition significantly increased light fraction C and N (LFOC, LFN), significantly decreased the light fraction C to N ratio (LFOC/N) (p < 0.05), and increased heavy fraction C and N (HFOC, HFN) accumulation and light fraction to total organic C ratio (LFOC/SOC, p > 0.05). Contrary to N addition, P addition was detrimental to the accumulation of LFOC, LFN and reduced LFOC/SOC. It was found that different reactive oxidized carbon (ROC) increased under N addition but ROC/SOC did not change, while N + P and P treatments increased ROC/SOC, resulting in a decrease in SOC chemical stability. Stable isotope analysis showed that N addition promoted the accumulation of new soil organic matter, whereas P addition enhanced the transformation and utilization of C and N from pre-existing organic matter. Additionally, N addition indirectly increased LFOC by significantly decreasing pH; significantly contributed to LFOC and ROC by increasing STN accumulation promoted by NO₃⁻-N and NH₄⁺-N; and decreased light fraction δ¹³C by significantly increasing dissolved organic C (p < 0.05). P addition had directly significant negative effect on LFOC and SOC (p < 0.05). In conclusion, six-year N deposition enhances soil C and N sequestration while the P enrichment reduces the content of soil C, N fractions and stability in Castanopsis sclerophylla forests. The results provide a scientific basis for predicting the soil C sink function of evergreen broad-leaved forest ecosystem under the background of future climate change. Full article

Background: Brain injuries, including stroke and traumatic brain injury (TBI), pose a major healthcare challenge due to their severe consequences and complex recovery. While ischemic strokes are more common, hemorrhagic strokes have a worse prognosis. TBI often affects young adults and leads to long-term disability. A critical concern in these patients is the frequent development of chronic critical illness, compounded by metabolic disturbances and malnutrition that hinder recovery. Objective: This study aimed to compare changes in nutritional status parameters under standard enteral nutrition protocols and clinical outcomes in prolonged/chronic critically ill patients with TBI or stroke versus such a population of patients without TBI or stroke. Methods: This matched prospective–retrospective cohort study included intensive care unit (ICU) patients with TBI or stroke from the Federal Research and Clinical Center of Intensive Care Medicine and Rehabilitology and patients without these conditions from the eICU-CRD database. Inclusion criteria comprised age 18–74 years, ICU stay >5 days, and enteral nutrition. Patients with re-hospitalization, diabetes, acute organ failure, or incomplete data were excluded. Laboratory values and clinical outcomes were compared between the two groups. Propensity score matching (PSM) was used to balance baseline characteristics (age, sex, and body mass index). Results: After PSM, 29 patients with TBI or stroke and 121 without were included. Univariate analysis showed significant differences in 21 laboratory parameters and three hospitalization outcomes. On day 1, the TBI/stroke group had higher hemoglobin, hematocrit, lymphocytes, total protein, and albumin, but lower blood urea nitrogen (BUN), creatinine, and glucose. By day 20, they had statistically significantly lower calcium, BUN, creatinine, and glucose. This group also showed less change in lymphocytes, calcium, and direct bilirubin. Hospitalization outcomes showed longer mechanical ventilation duration (p = 0.030) and fewer cases of acute kidney injury (p = 0.0220) in the TBI/stroke group. Conclusions: TBI and stroke patients exhibit unique metabolic patterns during prolonged/chronic critical illness, differing significantly from other ICU populations in protein/glucose metabolism and complication rates. These findings underscore the necessity for specialized nutritional strategies in neurocritical care and warrant further investigation into targeted metabolic interventions. Full article

In the context of China’s ecosystem facing a high intensity of nitrogen loads, carbon–nitrogen interactions are receiving increasing attention. Physical protection by soil aggregates is critical for soil carbon and nitrogen sequestration in terrestrial ecosystems; however, there is currently limited information on how nitrogen addition influences carbon and nitrogen dynamics across different stages of forest ageing. Herein, a field nitrogen manipulation experiment over 6 years was established in subtropical forests (46, 78, and about 200 years old) in China. Aggregate fractions and stable isotope analyses were used to assess the effects of nitrogen addition. The results show that forest soil was dominated by macroaggregates, and these increased with forest ageing (p > 0.05). The macroaggregates’ carbon content decreased with forest ageing (p > 0.05), while the macroaggregates’ nitrogen content was highest in the 200-year-old forest. Nitrogen addition increased the aggregates’ carbon and nitrogen concentrations in the 46- and 200-year-old forests. The macroaggregates, under nitrogen addition in the 78- and 200-year-old forests, were relatively weak, while forest age and nitrogen addition mainly affected macroaggregate carbon and nitrogen concentrations to promote their carbon and nitrogen storage, and the macroaggregates were the main storage unit for fixing and protecting new carbon in soils. Nitrogen addition increased the macroaggregates’ δ¹³C abundance in the 78- and 200-year-old forests and decreased it in the 46-year-old forest (p > 0.05); significantly increased the macroaggregates’ δ¹⁵N in the 46-year-old forest (p < 0.05), and decreased the macroaggregates’ δ¹⁵N in the 200-year-old forest (p > 0.05). Considering the distribution of δ¹³C and δ¹⁵N in the aggregates, the effect of nitrogen addition on the dynamic mechanism of soil aggregate carbon and nitrogen fractions varied based on forest age and aggregate size. Correlation analysis further revealed that soil total phosphorus, NH₄⁺-N, NO₃⁻-N, dissolved organic nitrogen, pH, texture, etc., were the primary predictors explaining most of the variation in aggregate fractions and their δ¹³C distribution. In summary, the effect of nitrogen deposition on the carbon and nitrogen stability of soil aggregates in broad-leaved forests depends on forest age. Full article

This study developed biodegradable levan–chitosan composite films for beef filet packaging, optimizing their functional properties and assessing their efficacy in food preservation. Films were prepared via solution casting using varying levan–chitosan ratios (100:0, 75:25, 50:50, 25:75, 0:100) with glycerol (30%) as a plasticizer. The L25:C75 formulation exhibited superior mechanical properties (tensile strength: 15.43 ± 0.04 MPa; elongation at break: 35.37 ± 1.12%) and high-water solubility (46.64 ± 0.37%). FTIR analysis confirmed intermolecular interactions between levan and chitosan. The films demonstrated strong antioxidant activity (91% ABTS•+ inhibition) and broad-spectrum antibacterial effects, with inhibition zones of 18 ± 0.30 mm against E. coli and 16 ± 0.20 mm against S. aureus. When applied to beef filets stored at 4 °C for 7 days, the L25:C75 films reduced total viable bacterial counts by 1.8 log CFU/g compared to LDPE packaging. Biodegradability tests revealed a 68% degradation rate for high-levan films (L75:C25) after 14 days in soil. These results highlight the potential of levan–chitosan films as sustainable, active packaging materials to extend food shelf life while addressing environmental concerns. Full article

Pulmonary metastasectomy for colorectal cancer represents a key component in modern oncological surgery, balancing precision resection with systemic disease management. Despite ongoing debate initiated by randomized trials, the surgical removal of lung metastases continues to offer significant survival benefits in well-selected patients. This review synthesizes the evolving landscape of pulmonary metastasectomy, integrating classical prognostic indicators, such as the disease-free interval (DFI) and carcinoembryonic antigen (CEA) levels, with emerging molecular insights including KRAS and BRAF mutations. The relationship between surgical radicality, systemic therapies, and personalized genetic profiling is redefining patient selection and optimizing outcomes. By dissecting recent evidence and ongoing controversies, we clarify the complex decision-making required to navigate this complex clinical terrain. Ultimately, the synergy of multidisciplinary care and precision surgery holds the promise of durable disease control and extended survival in colorectal cancer patients with lung metastases. Full article

Tracheostomy, a critical airway intervention, has a long and complex history that dates back to antiquity. While the earliest references to the procedure appear in Egyptian and Indian medical texts, its development within ancient Greek medicine remains a subject of historical debate. This study explores the evolution of tracheostomy in ancient Greece, analyzing its theoretical foundations, historical accounts, and surgical advancements. Despite Hippocratic opposition, which largely discouraged invasive airway procedures due to the risk of fatal complications, later physicians such as Asclepiades, Aretaeus, and Antyllus made significant contributions to refining airway management techniques. The anatomical studies of Galen further advanced the understanding of respiratory physiology, including early concepts of artificial ventilation. Additionally, this study examines archaeological evidence, such as a marble relief discovered in Abdera, which may depict an early attempt at tracheostomy, providing valuable insight into the practical application of airway interventions in antiquity. By comparing ancient Greek surgical techniques with modern tracheostomy practices, this research highlights the continuity of medical knowledge and innovation. It underlines the role of ancient Greek physicians in shaping the principles of thoracic surgery, offering a broader understanding of how early medical practices have influenced contemporary airway management. The findings contribute to the historical perspective on tracheostomy, emphasizing the timeless pursuit of life-saving surgical advancements and the evolving relationship between theoretical medical knowledge and practical surgical application. Full article

Understanding glacier and climate variations since pre-Industrial times is crucial for evaluating the present-day glacier response to climate change. Here, we focus on twelve small glaciers (≤2.0 km²) on both the northern and southern slopes of the Greater Caucasus to assess post-Little Ice Age glacier–climate fluctuations in this region. We reconstructed the Little Ice Age glacier extent using a manual detection method based on moraines. More recent glacier fluctuations were reconstructed using historical topographical maps and satellite imagery. Digital elevation models were used to estimate the topographic characteristics of glaciers. We also used the accumulation area ratio (AAR) method and a regional temperature lapse rate to reconstruct glacier snowlines and corresponding temperatures since the 1820s. The results show that all selected glaciers have experienced area loss, terminus retreat, and equilibrium line altitude (ELA) uplift over the last 200 years. The total area of the glaciers has decreased from 19.1 ± 0.9 km² in the 1820s to 9.7 ± 0.2 km² in 2020, representing a −49.2% loss, with an average annual reduction of −0.25%. The most dramatic reduction occurred between the 1960s and 2020, when the glacier area shrank by −35.5% or −0.59% yr⁻¹. The average terminus retreat for all selected glaciers was −1278 m (−6.4 m/yr⁻¹) during the last 200 years, while the average retreat over the past 60 years was −576 m (−9.6 m/yr⁻¹). AAR-based (0.6 ± 0.05) ELA reconstructions from all twelve glaciers suggest that the average ELA in the 1820s was about 180 m lower (3245 ± 50 m a.s.l.) than today (3425 ± 50 m a.s.l.), corresponding to surface air temperatures <1.1 ± 0.3 °C than today (2001–2020). The largest warming occurred between the 1960s and today, when snowlines rose by 105 m and air temperatures increased by <0.6 ± 0.3 °C. This study represents a first attempt at using glacier evidence to estimate climate changes in the Caucasus region since the Little Ice Age, and it can be used as a baseline for future studies. Full article

In this research, the results of the analysis of Enguri Large Dam (West Georgia) monitoring features, such as foundation displacement data and water level (WL) variation in the reservoir, were investigated. A statistical approach based on calculating time series helps us determine the research area’s dynamic picture. In this article, we have used various nonlinear analysis methods. Nonlinear dynamics of deformation and filling/reloading near grand dams reflect the complexity of the mentioned time series, connected with the natural agents (regional and local geodynamics), which were presented even before dam erection, and the effects of the water level variation in the reservoir. Both these effects are documented by observations from 1974 to 2024 at the Enguri Large Dam. Modern linear and nonlinear primarily data analysis techniques will be used for analysis of monitoring characteristics of the Enguri Large Dam: Kullback–Leibler divergence, mutual information, Shannon entropy, and Tsallis entropy. The obtained data on the dynamics of deformation and filling/reloading near a large dam can be used for the assessment of the possible risks connected with abrupt changes in the routine dynamics of construction. Full article

Background/Objectives: Surgical procedures in chronic obstructive pulmonary disease (COPD) patients carry a high risk of postoperative respiratory failure, often causing the need for mechanical ventilation and prolonged intensive care unit (ICU) stays. Accompanying COPD with heart failure further increases the risk of complications. This study aimed to identify predictors of mortality, prolonged ICU and hospital stays, the need for mechanical ventilation, and vasoactive drug usage in ICU patients with moderate to severe COPD undergoing elective non-cardiac surgery. Methods: This retrospective cohort study analyzed eICU-CRD data, including adult patients with moderate to severe COPD admitted to the ICU from the operating room following elective non-cardiac surgery. Spearman’s correlation analysis was performed to assess associations between intraoperative ventilation parameters and ICU/hospital length of stay, postoperative laboratory parameters, and their perioperative dynamics. Results: This study included 680 patients (21% with severe COPD). Hospital and ICU mortality were 8.6% and 4.4%, respectively. Median ICU and hospital stays were 1.9 and 6.6 days, respectively. Intraoperative tidal volume, expired minute ventilation, positive end-expiratory pressure, mean airway pressure, peak inspiratory pressure, and compliance had no statistically significant association with mortality, postoperative mechanical ventilation, its duration, or the use of vasopressors/inotropes. Tidal volume correlated positively with changes in monocyte count (R = 0.611; p = 0.016), postoperative lymphocytes (R = 0.327; p = 0.017), and neutrophil count (R = 0.332; p = 0.02). Plateau pressure showed a strong positive association with the neutrophil-to-lymphocyte ratio (R = 0.708; p = 0.001). Conclusions: Intraoperative ventilation modes and parameters in COPD patients appear to have no significant impact on the outcomes or laboratory markers, except possibly for the neutrophil-to-lymphocyte ratio, although its elevation cause remains unclear. Full article

Levansucrases are key enzymes responsible for the synthesis of β-2,6-linked fructans, found in plants and microbes, especially in bacteria. Levansucrases have been applied in the production of levan biopolymer and fructooligosaccharides (FOSs) using sucrose as a substrate as well as in reducing sugar levels in fruit juice. As a result, levansucrases that are active at low temperatures are required for industrial applications to maintain product stability. Therefore, this work firstly reports the novel cold-active levansucrase (SacBPk) isolated from a sucrolytic bacterial strain, P. koreensis HL12. The SacBPk was classified into glycoside hydrolase family 68 subfamily 1 (GH68_1) and comprised a single catalytic domain with the Asp104/Asp267/Glu362 catalytic triad. Interestingly, the recombinant SacBPk demonstrated cold-active levansucrase activity at low temperatures (on ice and 4–40 °C) with the highest specific activity (167.46 U/mg protein) observed at 35 and 40 °C in 50 mM sodium phosphate buffer pH 6.0. SacBPk mainly synthesized levan polymer as the major product (129 g/L, corresponding to 25.8% of total sugar) with a low number of short-chain FOSs (GF2–4) (12.8 g/L, equivalent to 2.5% of total sugar) from 500 g/L sucrose after incubating at 35 °C for 48 h. These results demonstrate the industrial application potential of SacBPk levansucrase for levan and FOSs production. Full article

Background: Ultrasonographic assessment of the diameters of various veins and their indices are among the most applied diagnostic tools for evaluating fluid responsiveness in clinical practice. Despite their widespread use, there is no definitive answer on which is preferable. Our study aimed to investigate the diagnostic accuracy of different venous diameters and their indices to assess fluid responsiveness. Methods: We conducted a systematic review and network meta-analysis, analyzing prospective studies evaluating the diagnostic accuracy of venous diameters (inferior vena cava [IVC], internal jugular vein [IJV], superior vena cava, and subclavian vena) and their indices for fluid responsiveness. Electronic databases were searched from inception until March 2024; this search was supplemented by snowballing methods. The risk of bias was evaluated with QUADAS-2, and evidence certainty was assessed using the GRADE approach. Nine prospective cohort studies (560 patients) were included. Results: The network meta-analysis revealed that the ΔCaval index exhibited a significant performance advantage over other “venous” test parameters. The caval index significantly outperformed IJV min/max and IVCmax. IJV index and IVCmin significantly outperformed IJVmin/max. The caval index was comparable to the IJV index. The caval index was comparable during mechanical ventilation and spontaneous breathing. Conclusions: In this meta-analysis, the ΔCaval index test showed higher diagnostic accuracy for fluid responsiveness compared with other venous tests. Caval and jugular indices displayed similar accuracy, and caval indices were consistent under mechanical ventilation and spontaneous breathing. Indices generally outperformed absolute values, except for IVCmin, which equaled the caval index in efficacy. This study was registered on the International Platform for Registered Protocols for Systematic Reviews and Meta-Analyses: INPLASY202430104. Full article

Background: Artificial intelligence (AI) has emerged as a transformative technology in healthcare, with its integration into cardiac surgery offering significant advancements in precision, efficiency, and patient outcomes. However, a comprehensive understanding of AI’s applications, benefits, challenges, and future directions in cardiac surgery is needed to inform its safe and effective implementation. Methods: A systematic review was conducted following PRISMA guidelines. Literature searches were performed in PubMed, Scopus, Cochrane Library, Google Scholar, and Web of Science, covering publications from January 2000 to November 2024. Studies focusing on AI applications in cardiac surgery, including risk stratification, surgical planning, intraoperative guidance, and postoperative management, were included. Data extraction and quality assessment were conducted using standardized tools, and findings were synthesized narratively. Results: A total of 121 studies were included in this review. AI demonstrated superior predictive capabilities in risk stratification, with machine learning models outperforming traditional scoring systems in mortality and complication prediction. Robotic-assisted systems enhanced surgical precision and minimized trauma, while computer vision and augmented cognition improved intraoperative guidance. Postoperative AI applications showed potential in predicting complications, supporting patient monitoring, and reducing healthcare costs. However, challenges such as data quality, validation, ethical considerations, and integration into clinical workflows remain significant barriers to widespread adoption. Conclusions: AI has the potential to revolutionize cardiac surgery by enhancing decision making, surgical accuracy, and patient outcomes. Addressing limitations related to data quality, bias, validation, and regulatory frameworks is essential for its safe and effective implementation. Future research should focus on interdisciplinary collaboration, robust testing, and the development of ethical and transparent AI systems to ensure equitable and sustainable advancements in cardiac surgery. Full article

Microorganisms synthesize diverse types of exopolysaccharides (EPSs). EPSs with varying structural and physical properties can demonstrate unique health benefits, which allow for their tailored applications as functional foods such as prebiotics. Levan, a fructose-based EPS, is gaining considerable attention as an effective prebiotic to support the growth of beneficial gut bacteria. Consequently, this enhances digestive health, boosts the immune system, and reduces the risk of chronic diseases. Unfortunately, limited studies are available on levan-type EPSs to demonstrate their role as prebiotics. Therefore, in this study, we conducted in vitro and in vivo experiments, concerning intestinal cell integrity and metabolic syndrome, to assess the therapeutic potential of levan derived from Lactobacillus reuteri FW2. The in vitro experimental results revealed that levan improved the survival of impaired HT-29 epithelial cells of the intestine and also exerted antioxidant effects. In the in vivo experiments, mice fed with levan-supplemented feed exhibited low body weight gain, blood glucose, and serum cholesterol levels compared to the control group. These findings highlight the biotherapeutic potential of L. reuteri FW2-derived levan for improving metabolic syndrome and its associated aspects. It also signifies the need for a further detailed investigation based on clinical trials to include levan in dietary supplements for improved health and well-being. Full article

Distinguishing between endo- and exo-type enzymes within the glycoside hydrolase (GH) classification presents significant challenges. Traditional methods, often based on endpoint activity measurements, do not capture the full range of products generated, leading to inconsistencies in classification. Not all exo-acting fructanases and glucanases produce monosaccharides (like fructose or glucose), while endo-acting enzymes do not solely produce higher-degree polymerization oligosaccharides. In practice, both enzyme types can yield a variety of products throughout the reaction, complicating classification efforts. To address these challenges, we propose a refined nomenclature system for GH enzymes, including fructanases and glucanases, based on good practices and initial product formation. This system classifies enzymes into four categories for each type: Fr, Fn, Fn,n+1 and F1 for fructanases, and Gr, Gn, Gn,n+1 and G1 for glucanases, based on their mode of action (endo- or exo-based) and initial product profiles. Our refined nomenclature system will advance enzyme structure–function research and support the production and application of fructan and glucan oligosaccharides as prebiotics, priming agents, and potential signaling molecules in microbe–microbe and plant–microbe interactions. Ultimately, this system could benefit agronomy and the food industry, contributing to health improvements. Full article

Geological mapping provides vital information about the structure, evolution, natural resource potential, and geohazards of a specific area. The role of geological mapping is especially valuable for mountainous countries like Georgia. In this context, we present a geological map of the Mulkhura River Valley in the Georgian Caucasus (43°3′ N, 42°52′ E) with accompanying cross-sections at a scale of 1:30,000, covering approximately 220 km². The geological information in the map is based on a comprehensive review of previously published geological maps and literature, combined with original analysis of satellite imagery and hitherto unpublished field data. The extensive spatial coverage and accompanying cross-sections provide detailed insights into the structure of the region. This new map will serve as a foundation for future geological research, hazard management, and resource exploration in the area, as well as for geoconservation to develop the national geotourism industry in this region. Full article