Physiological Resistance Research Articles

NGF effects promote the maturation of rat pancreatic beta cells by regulating GLUT2 levels and distribution, and glucokinase activity.

The nerve growth factor (NGF) participates in cell survival and glucose-stimulated insulin secretion (GSIS) processes in rat adult beta cells. GSIS is a complex process in which metabolic events and ionic channel activity are finely coupled. GLUT2 and glucokinase (GK) play central roles in GSIS by regulating the rate of the glycolytic pathway. The biphasic release of insulin upon glucose stimulation characterizes mature adult beta cells. On the other hand, beta cells obtained from neonatal, suckling, and weaning rats are considered immature because they secrete low levels of insulin and do not increase insulin secretion in response to high glucose. The weaning of rats (at postnatal day 20 in laboratory conditions) involves a dietary transition from maternal milk to standard chow. It is characterized by increased basal plasma glucose levels and insulin levels, which we consider physiological insulin resistance. On the other hand, we have observed that incubating rat beta cells with NGF increases GSIS by increasing calcium currents in neonatal cells. In this work, we studied the effects of NGF on the regulation of cellular distribution and activity of GLUT2 and GK to explore its potential role in the maturation of GSIS in beta cells from P20 rats. Pancreatic islet cells from both adult and P20 rats were isolated and incubated with 5.6 mM or 15.6 mM glucose with and without NGF for 4 hours. Specific immunofluorescence assays were conducted following the incubation period to detect insulin and GLUT2. Additionally, we measured glucose uptake, glucokinase activity, and insulin secretion assays at 5.6 mM or 15.6 mM glucose concentrations. We observed an age-dependent variation in the distribution of GLUT2 in pancreatic beta cells and found that glucose plays a regulatory role in GLUT2 distribution independently of age. Moreover, NGF increases GLUT2 abundance, glucose uptake, and GSIS in P20 beta cells and GK activity in adult beta cells. Our results suggest that besides increasing calcium currents, NGF regulates metabolic components of the GSIS, thereby contributing to the maturation process of pancreatic beta cells.

The future of artificial hibernation medicine: protection of nerves and organs after spinal cord injury.

Spinal cord injury is a serious disease of the central nervous system involving irreversible nerve injury and various organ system injuries. At present, no effective clinical treatment exists. As one of the artificial hibernation techniques, mild hypothermia has preliminarily confirmed its clinical effect on spinal cord injury. However, its technical defects and barriers, along with serious clinical side effects, restrict its clinical application for spinal cord injury. Artificial hibernation is a future-oriented disruptive technology for human life support. It involves endogenous hibernation inducers and hibernation-related central neuromodulation that activate particular neurons, reduce the central constant temperature setting point, disrupt the normal constant body temperature, make the body "adapt" to the external cold environment, and reduce the physiological resistance to cold stimulation. Thus, studying the artificial hibernation mechanism may help develop new treatment strategies more suitable for clinical use than the cooling method of mild hypothermia technology. This review introduces artificial hibernation technologies, including mild hypothermia technology, hibernation inducers, and hibernation-related central neuromodulation technology. It summarizes the relevant research on hypothermia and hibernation for organ and nerve protection. These studies show that artificial hibernation technologies have therapeutic significance on nerve injury after spinal cord injury through inflammatory inhibition, immunosuppression, oxidative defense, and possible central protection. It also promotes the repair and protection of respiratory and digestive, cardiovascular, locomotor, urinary, and endocrine systems. This review provides new insights for the clinical treatment of nerve and multiple organ protection after spinal cord injury thanks to artificial hibernation. At present, artificial hibernation technology is not mature, and research faces various challenges. Nevertheless, the effort is worthwhile for the future development of medicine.

Non-contact detection of pyrethroids widely used in vector control by Anopheles mosquitoes.

Pyrethroids are the most widely used insecticides to control vector borne diseases including malaria. Physiological resistance mechanisms to these insecticides have been well described, whereas those for behavioral resistance remain overlooked. Field data suggest the presence of spatial sensory detection by Anopheles mosquitoes of the pyrethroid molecules used in insecticide-based control tools, such as long-lasting insecticide nets or insecticide residual spraying. This opens the way to the emergence of a wide range of behavioral adaptations among malaria vectors. However, the spatial sensory detection of these molecules is controversial and needs to be demonstrated. The goal of this study was to behaviorally characterize the non-contact detection of three of the most common pyrethroids used for malaria vector control: permethrin, deltamethrin an ⍺-cypermethrin. To reach this goal, we recorded the behavior (takeoff response) of Anopheles gambiae pyrethroid-sensitive and resistant laboratory strains, as well as field collected mosquitoes from the Gambiae Complex, when exposed to the headspace of bottles containing different doses of the insecticides at 25 and 35°C, in order to represent a range of laboratory and field temperatures. We found the proportion of laboratory susceptible and resistant female mosquitoes that took off was, in all treatments, dose and the temperature dependent. Sensitive mosquitoes were significantly more prone to take off only in the presence of ⍺-cypermethrin, whereas sensitive and resistant mosquitoes showed similar responses to permethrin and deltamethrin. Field-collected mosquitoes of the Gambiae Complex were also responsive to permethrin, independently of the species identity (An. gambiae, An. coluzzii and An. arabiensis) or their genotypes for the kdr mutation, known to confer resistance to pyrethroids. The observed ability of Anopheles spp. mosquitoes to detect insecticides without contact could favor the evolution of behavioral modifications that may allow them to avoid or reduce the adverse effect of insecticides and thus, the development of behavioral resistance.

Structural analysis of prognostic diagnostics of cardiovascular system adaptive capacity and assessment of psycho physiological resistance to stressоgenic cognitive loads.

Aim: To conduct a structural analysis of cardiological signs of adaptation to stressogenic cognitive loads by identifying factor features of correlations between heart rate variability (HRV) and coping-testing data indicators. Materials and Methods: 43 people aged 19.7±1.8 years (23 boys and 20 girls) were monitored for their HRV. Methods included DC-06000 portable ECG recorder, 3X series "badge" type (single channel) and COPE Test. The study process includes four stages. Results: As a result of further factor correlation analysis, it was revealed that Factor 1 "HRV Stress Indicators" has a negative correlation (p<0.05) of "moderate" strength ρs= -0.363 with Factor 2 "Strategies to avoid problems and stresses" and a positive correlation of "weak" strength ρs=0.167 with Factor 3 "Psychoemotional Indicators". If two factors correlate with each other, it indicates they are related and can interact, which is important for adequate interpretation of the results of factor analysis. Conclusions: Structural analysis of the complex of cardiological signs of adaptivity to stressogenic cognitive loads and coping-testing data revealed the existence of three correlated factors: Factor 1 "HRV Stress Scores", Factor 2 "Strategies to avoid problems and stress", Factor 3 "Psychoemotional indicators". The revealed negative correlation of Factors 1 and 2 may indicate that in case the impact of Factor 2 "Strategies to avoid problems and stress" increases, the intensity of Factor 1 "HRV Stress Scores" (i.e., stress signs according to the indicators of heart rate variability) may decrease.

Современный взгляд на метаболические особенности детского ожирения и его осложнения

INTRODUCTION: Over the past several decades, the problem of pediatric exogenous constitutional obesity has acquired the status of a non-infectious pandemic of the 21st century. Statistics shows that both the prevalence of overweight and obese children and the incidence of morbid obesity, its complications and metabolic syndrome are increasing, which most is alarming for healthcare workers. This tendency requires specialists to understand the metabolic bases of formation of obesity, to search for new ways to treat and prevent the disease, as well as to prevent the development of complications. CONCLUSION: The given review considers the main features of metabolic alterations in the formation of childhood obesity, which can be an additional risk factor for both the development of the disease itself, and of its complications, the main ones being physiological insulin resistance of adolescents and a significant secretion of insulin-like growth factor-1 in children in the period of active growth. Understanding of metabolic features of the development of obesity at the pathophysiological and biochemical levels can become the basis for development of the ways to influence these processes. Of attention is the fact of a high prevalence of obesity complications and metabolic syndrome in childhood, with a continuing tendency to growth proportional to increase in the prevalence of obesity itself. A key point is the current absence of ways to predict obesity complications in children. Taking into account very limited possibilities of treatment of childhood obesity and its complications, the existence of prognostic markers may contribute to prevention or earlier, timely diagnosis of the main obesity complications, with a further decline of disability and mortality at a young age, as well as a considerable improvement of the quality of life of obese patients. The presented data require an in-depth analysis of mechanisms of development of childhood obesity — one of the most common problems in the world, and permit to reconceive the problems of treatment and prevention, to open up new prospects for creation of new approaches to diagnosis and control of this disease and its complications.

Interkingdom Hormonal Regulations between Plants and Animals Provide New Insight into Food Safety.

Food safety has become an attractive topic among consumers. Raw material production for food is also a focus of social attention. As hormones are widely used in agriculture and human disease control, consumers' concerns about the safety of hormone agents have never disappeared. The present review focuses on the interkingdom regulations of exogenous animal hormones in plants and phytohormones in animals, including physiology and stress resistance. We summarize these interactions to give the public, researchers, and policymakers some guidance and suggestions. Accumulated evidence demonstrates comprehensive hormonal regulation across plants and animals. Animal hormones, interacting with phytohormones, help regulate plant development and enhance environmental resistance. Correspondingly, phytohormones may also cause damage to the reproductive and urinary systems of animals. Notably, the disease-resistant role of phytohormones is revealed against neurodegenerative diseases, cardiovascular disease, cancer, and diabetes. These resistances derive from the control for abnormal cell cycle, energy balance, and activity of enzymes. Further exploration of these cross-kingdom mechanisms would surely be of greater benefit to human health and agriculture development.

Impact of post-dilatation on post-procedural physiology, microcirculatory resistance, and target vessel failure in STEMI patients undergoing PPCI: A single-center experience

BackgroundSuboptimal stent deployment is frequently observed in ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PPCI). This study sought to investigate whether these patients could benefit from post-dilatation with respect to post-procedural physiology, microcirculatory resistance, and long-term clinical outcomes. MethodsThis was a retrospective study of consecutive STEMI patients who underwent successful stent implantation during PPCI from February 2016 to November 2021. Post-procedural physiology and microcirculatory resistance were assessed by Murray law-based quantitative flow ratio (μQFR) and angiographic microcirculatory resistance (AMR), respectively. The primary outcome was target vessel failure (TVF), a composite of cardiac death, target vessel-oriented myocardial infarction, and clinically driven target vessel revascularization. ResultsA total of 671 patients (671 culprit vessels) were included. Post-dilatation was selectively performed in 430 (64.1%) culprit vessels, resulting in a 0.02 (interquartile range: 0.00–0.05, p < 0.001) increase in post-procedural μQFR but no significant impact on AMR. During a median follow-up of 2.8 years (interquartile range: 1.4–3.0 years), TVF occurred in 47 (7.0%) patients. Post-dilatation demonstrated a trend toward a reduction in TVF (5.3% vs. 10.0%; adjusted hazard ratio: 0.60, 95% confidence interval: 0.33–1.09, p = 0.094), mainly driven by a lower incidence of clinically driven target vessel revascularization (1.6% vs. 4.1%; adjusted hazard ratio: 0.32, 95% confidence interval: 0.11–0.90, p = 0.030). ConclusionsIn STEMI patients undergoing PPCI, selective post-dilatation was associated with improved post-procedural physiological results and a trend toward less TVF events without aggravating microcirculatory resistance.

Intestinal effects of modern insecticides on multiresistant strains of the housefly Musca domestica

Under laboratory conditions, resistance to insecticides in several strains of the housefly, Musca domestica, obtained from populations collected at various facilities in the Moscow and Kaluga regions, was assessed by intestinal ingestion of insecticidal baits. The insects of the strains Krasnogorsk and Kaluga had the highest resistance ratios to fipronil (23.3–76.7x), while those of the KSK-1 and KSK-2 strains were tolerant (6.3–7.7x). The strains Krasnogorsk, KSK-1, KSK-2 and Kaluga are highly resistant to neonicotinoids (thiamethoxam 80.4–104.8x and clothianidin 79.5–97.9x), weakly tolerant to chlorfenapyr (1.8–2.8x) and highly susceptible to indoxacarb (0.22–0.54x). A comparison was made of the contact and intestinal effects of insecticides against the housefly. The resistance factor of the housefly to fipronil, thiamethoxam, and clothianidin upon contact is 1.5–4.4 times higher than those after feeding with the similar insecticide dose. Possible mechanisms of insect multiresistance to insecticides are discussed. Comparative evaluation using three strains of the housefly showed that a number of industrially produced baits are effective for control of the field populations of the house fly. Physiological resistance of the housefly of Krasnogorsk and Kaluga strains to baits based on methomyl was shown.

Hydraulics Facilitate Urban Forest Establishment by Informing Tree Dynamics under Drought

Urban forests provide considerable ecosystem services for city dwellers, yet the function of forest species is increasingly challenged by urban drought. Understanding drought tolerance of urban forest species would facilitate vegetation conservation and establishment within urban ecosystems. Here, we report on the drought resistance of leaves for two exotic and three indigenous tree species common to the Jing-Jin-Ji metropolitan region (covering Beijing, Tianjin, and Hebei province) of north China. Xylem vulnerability to drought-induced embolism and leaf gas exchange, together with various morphological and anatomical traits that potentially relate to plant water use, were measured for pot-grown seedlings. In addition, seedlings were subjected to dry-down at two different drought intensities until death, and the tree mortality rate was recorded. We found that species differ markedly in xylem embolism resistance, with indigenous species showing more negative P50 (the water potential triggering 50% loss of xylem hydraulic conductivity), but less canopy leaf area at a given branch basal diameter, compared with exotic species. Furthermore, P50 well predicted tree mortality rate under protracted drought stress. Species characterized by more negative P50 also exhibited higher maximum leaf photosynthetic rates. In addition, leaf P50 was found to correlate with specific leaf area, while the hydraulic safety margin was related to sapwood density and the thickness of the leaf upper epidermis. Collectively, these results highlight the role of embolism resistance in dictating drought response and the promise of morphological traits as proxies of plant physiological drought resistance. Our findings contribute to understanding drought response for urban tree species and will guide the establishment and management of urban forests.

Intercropping and appropriate nitrogen application control faba bean Fusarium wilt by improving physiological and biochemical resistance and protein expression of faba bean

AbstractThis study set up four nitrogen application levels (0, 45, 90 and 135 kg/ha) and two planting systems (faba bean monocropping and faba bean and wheat intercropping) to investigate the incidence of faba bean Fusarium wilt under different treatments and determine the resistance enzyme activities and gene expression, protein expression, and other indexes of faba bean plants. At all N levels, faba bean and wheat intercropping controlled faba bean Fusarium wilt by decreasing the content of hydrogen peroxide and superoxide anion in faba bean roots, increasing the enzyme activity and gene expression of the superoxide dismutase and the gene expression of pathogenesis‐related protein 1 (VfPR1), VfPR2, VfPR5 and VfPR10 disease resistance proteins in the roots, with the most significant effects at the N2 level (90 kg/ha). Further investigation of the impact of intercropping on faba bean roots using the N2 treatment showed that faba bean–wheat intercropping upregulated 288 proteins and downregulated 179 proteins compared with monocropping, and the functions of the upregulated proteins were mainly related to energy metabolism, antioxidant enzymes, stress and DNA repair. GO functional analysis showed that the upregulated proteins were mainly focused on the involvement in amide biological processes. KEGG enrichment analysis revealed that faba bean–wheat intercropping upregulated proteins involved in glutathione metabolism and ascorbic acid metabolism. In summary, at the N2 level, faba bean–wheat intercropping effectively mitigated root oxidative stress by enhancing antioxidant and disease resistance mechanisms in faba bean roots.

Comparative physiological and immunological assessment of carp crosses

The main purpose of hybridization in the aquaculture industry is improving the productivity of hybrids compared to their parents in specific environmental conditions. The physiological state and resistance are judged by blood parameters, which are sensitive and informative indicators of the state of the body’s defense power and allow timely detection their changes under the influence of abiotic and biotic environmental factors. The article presents the results of studying of the productive and physiological properties of two-year-old carp crosses: interbreed hybrids of the first generation (F1). Shown, that the driveability index of the new threebreed carp cross is significantly lower than that of the “Surskiy Malokostny” and “Petrovskiy” crosses, which characterizes its high commercial qualities. The new three-breed cross has a lower swim bladder index: the lengths of the anterior and posterior chambers are almost equal. The number of vertebrae is less, compared to others. However, in the caudal region the number of vertebrae is close to that of the “Sursky Malokostny” cross and greater than that of the “Petrovsky”. In terms of size and weight indicators, the two-year-olds of the new three-breed carp cross exceeded those of other studied crosses, which indicates significant production potential. All recorded blood parameters of the studied fishes were within the limits of the physiological norm. The new three-breed cross is characterized by a high level of nonspecific cellular protection: a large proportion of microphages — segmented neutrophils is noted in the blood leukogram of the new cross. High immune resistance is evidenced by high vitality and a relatively low content of cationic protein in the lysosomes of neutrophils, which is consumed during immune defense when preparing fish for wintering. A comparative assessment of the crosses showed their excellent and productive marketable qualities, survival at different stages of ontogenesis, and good physiological and immunological status.

A high‐throughput analysis of high‐resolution X‐ray CT images of stems of olive and citrus plants resistant and susceptible to Xylella fastidiosa

AbstractThe bacterial plant pathogen Xylella fastidiosa causes disease in several globally important crops. However, some cultivars harbour reduced bacterial loads and express few symptoms. Evidence considering plant species in isolation suggests xylem structure influences cultivar susceptibility to X. fastidiosa. We test this theory more broadly by analysing high‐resolution synchrotron X‐ray computed tomography of healthy and infected plant vasculature from two taxonomic groups containing susceptible and resistant varieties: two citrus cultivars (sweet orange cv. Pera, tangor cv. Murcott) and two olive cultivars (Koroneiki, Leccino). Results found the susceptible plants had more vessels than resistant ones, which could promote within‐host pathogen spread. However, features associated with resistance were not shared by citrus and olive. While xylem vessels in resistant citrus stems had comparable diameters to those in susceptible plants, resistant olives had narrower vessels that could limit biofilm spread. And while differences among olive cultivars were not detected, results suggest greater vascular connectivity in resistant compared to susceptible citrus plants. We hypothesize that this provides alternate flow paths for sustaining hydraulic functionality under infection. In summary, this work elucidates different physiological resistance mechanisms between two taxonomic groups, while supporting the existence of an intertaxonomical metric that could speed up the identification of candidate‐resistant plants.

Physiology, gene expression, and epiphenotype of two Dianthus broteri polyploid cytotypes under temperature stress.

Increasing evidence supports a major role for abiotic stress response in the success of plant polyploids, which usually thrive in harsh environments. However, understanding the ecophysiology of polyploids is challenging due to interactions between genome doubling and natural selection. Here, we investigated physiological responses, gene expression, and the epiphenotype of two related Dianthus broteri cytotypes-with different genome duplications (4× and 12×) and evolutionary trajectories-to short extreme temperature events (42/28 °C and 9/5 °C). The 12× cytotype showed higher expression of stress-responsive genes (SWEET1, PP2C16, AI5L3, and ATHB7) and enhanced gas exchange compared with 4×. Under heat stress, both ploidies had greatly impaired physiological performance and altered gene expression, with reduced cytosine methylation. However, the 12× cytotype exhibited remarkable physiological tolerance (maintaining gas exchange and water status via greater photochemical integrity and probably enhanced water storage) while down-regulating PP2C16 expression. Conversely, 4× D. broteri was susceptible to thermal stress despite prioritizing water conservation, showing signs of non-stomatal photosynthetic limitations and irreversible photochemical damage. This cytotype also presented gene-specific expression patterns under heat, up-regulating ATHB7. These findings provide insights into divergent stress response strategies and physiological resistance resulting from polyploidy, highlighting its widespread influence on plant function.

Evaluation of the stability of physiological and behavioral resistance to imidacloprid in the house fly (Musca domestica L.) (Diptera: Muscidae).

The house fly (Musca domestica L.) is a synanthropic fly species commonly associated with confined animal facilities. House fly control relies heavily on insecticide use. Neonicotinoids are currently the most widely used class of insecticide and have been formulated into granular fly baits since 2002. Physiological resistance to imidacloprid in house flies has been observed to be unstable and decline over time without continual selection pressure, indicating that resistance has a fitness cost to individuals in the absence of exposure to insecticides. The stability of behavioral resistance to imidacloprid in the house fly has not been evaluated. In the current study, we assess the stability of physiological and behavioral resistance in house flies to imidacloprid over time. Physiological susceptibility to imidacloprid varied significantly among three house fly strains examined, with WT-15 exhibiting the greatest susceptibility to imidacloprid with an LC50 and LC95 of 109.29 (95.96-124.49) μg g-1 and 1486.95 (1097.15-2015.23) μg g-1 , respectively. No significant differences in survival were observed across 30 generations of a house fly strain (BRS-1) previously selected for behavioral resistance to imidacloprid with percentage survival ranging from 93.20% at F0 in 2020 to 96.20% survival at F30 in 2022. These results have significant implications for the management of house flies exhibiting behavioral resistance in field settings. It appears that standard resistance management tactics deployed to reduce the prevalence of physiological resistance, such as rotating or temporarily discontinuing the use of specific insecticides, may not lead to reduced behavioral resistance to imidacloprid. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effects of dietary synbiotic supplementation on growth performance, digestive enzyme activities, and physiological resistance against high stocking density in rainbow trout (Oncorhynchus mykiss)

Effects of dietary synbiotic supplementation on growth performance, digestive enzyme activities, and physiological resistance against high stocking density in rainbow trout (Oncorhynchus mykiss)

Stress response in bacteria originated from dairy products

Abstract In some bacteria, the stress adaptation response, a defence mechanism against low pH, can also induce a number of physiological and genetic resistance mechanisms that provide advantages for bacteria to resist other environmental factors. This phenomenon is called cross-protection, which can potentially have serious consequences for food safety. In some fermented, acidified foods, low pH can provide a favourable environment for the growth of bacteria. Bacteria can adapt to acidic environments and become able to survive various factors that occur during storage and processing such as salt, antibiotics, or technological effects. The microbiota of dairy products includes beneficial microorganisms, spoilage bacteria, and foodborne pathogens. The most common bacteria on various dairy products are Escherichia coli, Enterococcus sp., Staphylococcus sp., and Bacillus sp. The aim of this research is to determine the resistance of the identified bacteria (16S rDNA-based bacterial identification) to antibiotics and osmotic pressure as a consequence of their possible defence mechanisms adapted to the acidic environment.

EFFECT OF INDOLE EXTRACTED FROM UROPATHOGENIC E. coli ON SOME CELL LINES IN COMPARABLE WITH STANDARD INDOLE

Indole mechanism as an interspecies signal particle to adjust various physiological actions, like virulence, antimicrobial and acid resistance. This study was aimed to use partial purified indole extracted from uropathogenic E. coli and study the cytotoxic effect on some cancer cell lines (A375, HepG2, PC3) and comparable with normal cell line (WRL- 68). Serial dilutions of natural and synthetic standard indole were tested (400, 200, 100, 50, 25, 12.5, and 6.25 μg/mL). The results show a low cytotoxic effect for both natural and synthetic indoles in HepG2 and A375 cell lines as well as this degree of cytotoxicity was obviously appeared in normal cell line WRL-68 with no significant differences among them. While, both indoles effect was appeared high cytotoxic effect on PC3 cell line, this increasing has a significant difference with WRL-68. Thus, it can be suggesting that, this type of indole is not favorable for treatment of some types of cancer, and may has a specific biological activity against exact cancer cells.

Combined biochar and water-retaining agent application increased soil water retention capacity and maize seedling drought resistance in Fluvisols

Global climate change has accelerated the occurrence of agricultural drought events, which threaten food security. Therefore, improvements in the soil water retention capacity (WRC) and crop drought resistance are crucial for promoting the sustainability of the agricultural environment. In this study, we explored the effects of applying biochar and water-retaining agent (WRA) on soil WRC and crop drought resistance in a Fluvisols, along with their potential mechanisms. We applied two types of biochar (based on wheat and maize straw) and two WRAs (polyacrylamide and starch-grafted sodium acrylate) to Fluvisols with different textures, and then evaluated soil water retention and crop drought physiological resistance. The combined biochar and WRA treatment increased the WRC in both the sandy loam and clay loam Fluvisols. Biochar and WRA increased the relative content of soil hydrophilic functional groups. Compared with the control (CK), the combined application of biochar and WRA increased the field capacity, reduced soil water volatilization under drought conditions, and slowed water infiltration into the Fluvisols. The soil WRC was higher with the wheat straw biochar (WBC) treatment than with the maize straw biochar (MBC) treatment. It was also higher with polyacrylamide treatment than with the starch-grafted sodium acrylate treatment. The combined application of biochar and WRA improved crop drought physiological resistance by significantly increasing the maize seedling potassium (K) and soluble sugar contents, increasing antioxidant enzyme activity, and reducing the malondialdehyde (MDA) content. The results indicate that the application of biochar and WRA alleviated drought stress by increasing the soil WRC and improving crop drought resistance in Fluvisols.

Nonadditive functional interactions between ligand-binding sites of the multidrug efflux pump AdeB from Acinetobacter baumannii.

Multidrug efflux is one of the major mechanisms of antibiotic resistance identified in clinical isolates of the human pathogen Acinetobacter baumannii. The multiple antibiotic resistance in this species is often enabled by the overproduction of the tripartite efflux pump AdeABC. In this pump, AdeB is the inner membrane transporter from the resistance-nodulation-division (RND) superfamily of proteins, which is responsible for the recognition and efflux of multiple structurally unrelated compounds. Like other RND transporters, AdeB is a trimeric protein with ligand-binding sites located in the large periplasmic domains. Previous structural studies, however, highlighted the uniqueness of AdeB interactions with ligands. Up to three ligand molecules were bound to one protomer of AdeB, mapping its substrate translocation path. In this study, we introduced single and double substitutions in the identified ligand-binding sites of AdeB. Our results show that the mechanism of substrate translocation by AdeB is different from that of other characterized RND transporters and that the functional interactions between the sites are nonadditive. We identified AdeB mutants with both the loss and the gain of antibiotic susceptibility phenotypes, as well as AdeB mutations making A. baumannii cells overproducing such pump variants even more susceptible to multiple antibiotics than efflux-deficient cells. IMPORTANCE Multidrug efflux pumps of the resistance-nodulation-division superfamily of proteins are important contributors to various aspects of bacterial physiology and antibiotic resistance. Studies of the best-characterized model transporter AcrB from Escherichia coli suggested that these transporters operate by a functional rotation mechanism in which various substrates bind to at least two different binding sites. This study suggests that the mechanism of AdeB is distinct and that the binding sites in this transporter are functionally linked.

THU130 Long Term Tracking Of HbA1c Levels Across The Life Span In Type 1 Diabetes: From Infants To Young Adults

Abstract Disclosure: S. Kim: None. K. Song: None. M. Lee: None. J. Seo: None. H. Chae: None. H. Kim: None. A. Kwon: None. Objectives HbA1c is the most important monitoring value and generally used in diabetes. However, HbA1c may change across the life span according to growth and puberty. This study explores the long-term tracking of HbA1c from infants to young adults diagnosed with Type 1 Diabetes mellitus (T1DM) and analyzes the effects of HbA1c according to life span on complications. Method This retrospective study, included 289 patients (M, 43.0%; mean first visit age, 7.39±3.94 years old; mean followed up periods, 4.32±3.15 years) diagnosed with T1DM. The total of 6368 HbA1c values were analyzed. The distribution of HbA1c values according to age and life period was evaluated. In addition, the differences in mean HbA1c values according to sex and the use of continuous glucose monitoring (CGM) were analyzed. Furthermore, it was analyzed which HbA1c of life period has the most influence on occurrence of complications. Result The level of HbA1c was relatively high at the age of 1- to 2-years, and then decreased between 4 to 5-years. After 5 years of age, HbA1C gradually escalated and peaked at the age of 12- to 15-years, during puberty. Especially for girls, HbA1c increased dramatically during puberty between the age of 10- to 13-years, which was consistent with the physiologic insulin resistance. During in childhood to young adulthood, the mean HbA1c of CGM users was lower than that of non-users. The higher mean HbA1c during all ages affected the occurrence of complications. Intriguingly, the HbA1c level during adolescence was important for the occurrence of diabetic retinopathy. Conclusion HbA1c level change across life span, and peaked at pubertal stage, which consistent with physiologic insulin resistance during puberty. In addition, good glycemic control in adolescence may reduce the occurrence of diabetic retinopathy. Therefore, using CGM in adolescence may be helpful for glycemic control and prevention of diabetic complications. Presentation: Thursday, June 15, 2023