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Frontiers in Microbiology 2024The administration of antibiotics can expose the digestive microbiota of humans and animals to sub-inhibitory concentrations, potentially favouring the selection of...
The sub-MIC selective window decreases along the digestive tract: determination of the minimal selective concentration of oxytetracycline in sterilised intestinal contents.
INTRODUCTION
The administration of antibiotics can expose the digestive microbiota of humans and animals to sub-inhibitory concentrations, potentially favouring the selection of resistant bacteria. The minimal selective concentration (MSC) is a key indicator to understand this process. The MSC is defined as the lowest concentration of an antibiotic that promotes the growth of a resistant strain over a susceptible isogenic strain. It represents the lower limit of the sub-minimal inhibitory concentration (MIC) selective window, where resistant mutants can be selected. Previous studies focused on determining the MSC under standard culture conditions, whereas our research aimed to determine the MSC in a model that approximates conditions.
METHODS
We investigated the MSC of oxytetracycline (OTC) in Mueller-Hinton broth (MHB) and sterilised intestinal contents () from the jejunum, caecum and rectum (faeces) of pigs, using two isogenic strains of (one susceptible and one resistant to OTC). Additionally, the MIC of OTC against the susceptible strain was determined to assess the upper limit of the sub-MIC selective window.
RESULTS
Our study took a novel approach, and the results indicated that MIC and MSC values were lower in MHB than in . In the latter, these values varied depending on the intestinal segment, with distal compartments exhibiting higher MIC and MSC values. Moreover, the sub-MIC selective window of OTC in SIC narrowed from the jejunum to the rectum, with a significantly closer MSC to MIC in faecal .
DISCUSSION
The results suggest that OTC binds to digestive contents, reducing the fraction of free OTC. However, binding alone does not fully explain our results, and interactions between bacteria and intestinal contents may play a role. Furthermore, our findings provide initial estimates of low concentrations facilitating resistance selection in the gut. Finally, this research enhances the understanding of antimicrobial resistance selection, emphasising the intricate interplay between antibiotics and intestinal content composition in assessing the risk of resistance development in the gut.
PubMed: 38946898
DOI: 10.3389/fmicb.2024.1377159 -
International Journal of Nanomedicine 2024It is well-established that osteoclast activity is significantly influenced by fluctuations in intracellular pH. Consequently, a pH-sensitive gated nano-drug delivery...
BACKGROUND
It is well-established that osteoclast activity is significantly influenced by fluctuations in intracellular pH. Consequently, a pH-sensitive gated nano-drug delivery system represents a promising therapeutic approach to mitigate osteoclast overactivity. Our prior research indicated that naringin, a natural flavonoid, effectively mitigates osteoclast activity. However, naringin showed low oral availability and short half-life, which hinders its clinical application. We developed a drug delivery system wherein chitosan, as gatekeepers, coats mesoporous silica nanoparticles loaded with naringin (CS@MSNs-Naringin). However, the inhibitory effects of CS@MSNs-Naringin on osteoclasts and the underlying mechanisms remain unclear, warranting further research.
METHODS
First, we synthesized CS@MSNs-Naringin and conducted a comprehensive characterization. We also measured drug release rates in a pH gradient solution and verified its biosafety. Subsequently, we investigated the impact of CS@MSNs-Naringin on osteoclasts induced by bone marrow-derived macrophages, focusing on differentiation and bone resorption activity while exploring potential mechanisms. Finally, we established a rat model of bilateral critical-sized calvarial bone defects, in which CS@MSNs-Naringin was dispersed in GelMA hydrogel to achieve in situ drug delivery. We observed the ability of CS@MSNs-Naringin to promote bone regeneration and inhibit osteoclast activity in vivo.
RESULTS
CS@MSNs-Naringin exhibited high uniformity and dispersity, low cytotoxicity (concentration≤120 μg/mL), and significant pH sensitivity. In vitro, compared to Naringin and MSNs-Naringin, CS@MSNs-Naringin more effectively inhibited the formation and bone resorption activity of osteoclasts. This effect was accompanied by decreased phosphorylation of key factors in the NF-κB and MAPK signaling pathways, increased apoptosis levels, and a subsequent reduction in the production of osteoclast-specific genes and proteins. In vivo, CS@MSNs-Naringin outperformed Naringin and MSNs-Naringin, promoting new bone formation while inhibiting osteoclast activity to a greater extent.
CONCLUSION
Our research suggested that CS@MSNs-Naringin exhibited the strikingly ability to anti-osteoclasts in vitro and in vivo, moreover promoted bone regeneration in the calvarial bone defect.
Topics: Flavanones; Animals; Osteoclasts; Bone Regeneration; Silicon Dioxide; Hydrogen-Ion Concentration; Nanoparticles; Rats; Mice; Rats, Sprague-Dawley; Chitosan; Male; Drug Liberation; Porosity; Drug Carriers; Bone Resorption; RAW 264.7 Cells; Drug Delivery Systems; Cell Differentiation
PubMed: 38946884
DOI: 10.2147/IJN.S456545 -
Journal of Indian Prosthodontic Society Jul 2024Occurrence of denture stomatitis and prosthesis breakage are common problems faced by elderly people wearing removable dentures. To overcome this, several attempts are...
AIM
Occurrence of denture stomatitis and prosthesis breakage are common problems faced by elderly people wearing removable dentures. To overcome this, several attempts are made to improve the denture material by addition of antimicrobials without compromising original properties. The aim of the study was to evaluate flexural strength and microhardness of self-cured polymethyl methacrylate (PMMA) denture base resin after addition of Vaccinium macrocarpon (commonly called as cranberry), extract as antimicrobial, at varying proportions.
STUDY SETTING AND DESIGN
Experimental in vitro study.
MATERIALS AND METHODS
Frozen cranberry fruits were subjected to extraction process in the presence of aqueous solvents. Lyophilized extract was added in proportions of 0, 0.5, 1.0, 1.5, and 2.0 dry wt/wt % into polymer of self-cure PMMA denture base resin. Based on cranberry inclusion, the study comprised one control (0%) and four test groups (0.5%-2%) with total of 100 samples. A three-point bending test for flexural strength was done for fifty study samples (n = 10). Surface of fractured samples was analyzed using a scanning electron microscope (SEM). Microhardness was determined using Vickers hardness test.
STATISTICAL ANALYSIS USED
One-way statistical ANOVA test was done to find the difference between groups, followed by Tukey's post hoc test for multiple pairwise comparison.
RESULTS
Flexural strength ranged from 66.80 to 69.28 MPa, and a statistically insignificant difference was observed between groups (P > 0.05). SEM evaluation showed uniformly dispersed strands of cranberry extract in PMMA matrix. With higher concentration, less voids were seen. Vickers microhardness value significantly decreased from 15.96 in the control group to 14.57 with 2% cranberry addition (P < 0.05).
CONCLUSION
Incorporation of cranberry extract into self-cure PMMA denture base resin, up to 2 dry wt %, did not decline the flexural strength. However, there was a significant decrease in Vickers microhardness values when compared against the control group (0% cranberry inclusion).
Topics: Polymethyl Methacrylate; Hardness; Flexural Strength; Vaccinium macrocarpon; Plant Extracts; Materials Testing; Humans; Denture Bases; Dental Materials; Anti-Infective Agents; In Vitro Techniques
PubMed: 38946510
DOI: 10.4103/jips.jips_25_24 -
Animal Models and Experimental Medicine Jul 2024Hypothyroxinemia is a subclinical thyroid hormone deficiency in which the mother has inadequate levels of T during pregnancy. The fetus relies entirely on the mother's T...
BACKGROUND
Hypothyroxinemia is a subclinical thyroid hormone deficiency in which the mother has inadequate levels of T during pregnancy. The fetus relies entirely on the mother's T hormone level for early neurodevelopment. Isolated maternal hypothyroxinemia (IMH) in the first trimester of pregnancy can lead to lower intelligence, lower motor scores, and a higher risk of mental illness in descendants. Here, we focus on the autism-like behavior of IMH offspring.
METHODS
The animals were administered 1 ppm of propylthiouracil (PTU) for 9 weeks. Then, the concentrations of T, T, and thyroid-stimulating hormone (TSH) were detected using enzyme-linked immunosorbent assay (ELISA) to verify the developed animal model of IMH. We performed four behavioral experiments, including the marble burying test, open-field test, three-chamber sociability test, and Morris water maze, to explore the autistic-like behavior of 40-day-old offspring rats.
RESULTS
The ELISA test showed that the serum T and TSH concentrations in the model group were normal compared with the negative control group, whereas the T concentration decreased. In the behavioral experiments, the number of hidden marbles in the offspring of IMH increased significantly, the frequency of entering the central compartment decreased, and the social ratio decreased significantly.
CONCLUSION
The animal model of IMH was developed by the administration of 1 ppm of PTU for 9 weeks, and there were autistic-like behavior changes such as anxiety, weakened social ability, and repeated stereotyping in the IMH offspring by 40 days.
PubMed: 38946346
DOI: 10.1002/ame2.12459 -
Physiological Reports Jul 2024To better understand mechanisms of serotonin- (5-HT) mediated vasorelaxation, isolated lateral saphenous veins from cattle were assessed for vasoactivity using myography...
To better understand mechanisms of serotonin- (5-HT) mediated vasorelaxation, isolated lateral saphenous veins from cattle were assessed for vasoactivity using myography in response to increasing concentrations of 5-HT or selective 5-HT receptor agonists. Vessels were pre-contracted with 1 × 10 M phenylephrine and exposed to increasing concentrations of 5-HT or 5-HT receptor agonists that were selective for 5-HT, 5-HT, 5-HT, and 5-HT. Vasoactive response data were normalized as a percentage of the maximum contractile response induced by the phenylephrine pre-contraction. At 1 × 10 M 5-HT, a relaxation was observed with an 88.7% decrease (p < 0.01) from the phenylephrine maximum. At 1 × 10 M 5-HT, a contraction was observed with a 165% increase (p < 0.01) from the phenylephrine maximum. Increasing concentrations of agonists selective for 5-HT, 5-HT, or 5-HT resulted in a 27%, 92%, or 44% (p < 0.01) decrease from the phenylephrine maximum, respectively. Of these 5-HT receptor agonists, the selective 5-HT receptor agonist resulted in the greatest potency (-log EC) value (6.30) compared with 5-HT and 5-HT receptor agonists (4.21 and 4.66, respectively). To confirm the involvement of 5-HT in 5-HT-mediated vasorelaxation, blood vessels were exposed to either DMSO (solvent control) or a selective 5-HT antagonist (1 × 10 M) for 5-min prior to the phenylephrine pre-contraction and 5-HT additions. Antagonism of the 5-HT receptor attenuated the vasorelaxation caused by 5-HT. Approximately 94% of the vasorelaxation occurring in response to 5-HT could be accounted for through 5-HT, providing strong evidence that 5-HT-mediated vasorelaxation occurs through 5-HT activation in bovine peripheral vasculature.
Topics: Animals; Cattle; Vasodilation; Saphenous Vein; Serotonin; Receptors, Serotonin; Receptors, Serotonin, 5-HT4; Phenylephrine; Serotonin Receptor Agonists; Male
PubMed: 38946059
DOI: 10.14814/phy2.16128 -
Journal of Nutritional Science and... 2024Osteoporosis is characterized by bone loss and deterioration in bone microstructure, leading to bone fragility. It is strongly correlated with menopause in women....
Osteoporosis is characterized by bone loss and deterioration in bone microstructure, leading to bone fragility. It is strongly correlated with menopause in women. Previously, we reported that diets supplemented with a kudzu (Pueraria lobata) vine extract suppressed bone resorption in ovariectomized (OVX) mice, a postmenopausal model. The main isoflavone in kudzu is puerarin (daidzein-8-C-glycoside). Puerarin (daidzein-8-C-glycoside), which is main isoflavone of kudzu, probably contributes to the beneficial effect. However, the underlying mechanism is unclear. Therefore, the nutrikinetics of puerarin and the comparison with the suppressive effects of kudzu isoflavones on osteoclast differentiation was examined in this study. We demonstrated that orally administered puerarin was absorbed from the gut and entered the circulation in an intact form. In addition, puerarin accumulated in RAW264.7 pre-osteoclast cells in a time-dependent manner. Tartrate-resistant acid phosphatase activity was decreased by puerarin treatment in a concentration-dependent manner in RAW264.7 cells stimulated with the receptor activator of nuclear factor kappa-B ligand. Ovariectomy-induced elevated bone resorption was suppressed, and the fragile bone strength was improved by puerarin ingestion in the diet. These findings suggested that orally administered puerarin was localized in bone tissue and suppressed bone resorption and osteoclastogenesis in ovariectomized mice.
Topics: Animals; Isoflavones; Ovariectomy; Osteoclasts; Female; Mice; Femur; Pueraria; Cell Differentiation; RAW 264.7 Cells; Bone Resorption; Plant Extracts; Osteoporosis; Tartrate-Resistant Acid Phosphatase
PubMed: 38945892
DOI: 10.3177/jnsv.70.262 -
Food Research International (Ottawa,... Aug 2024The effect of 90, 180 and 270 mEq/kg of the calcium sequestering salts (CSS) disodium phosphate (DSP), trisodium citrate (TSC) and sodium hexametaphosphate (SHMP) on the...
The effect of 90, 180 and 270 mEq/kg of the calcium sequestering salts (CSS) disodium phosphate (DSP), trisodium citrate (TSC) and sodium hexametaphosphate (SHMP) on the solubilisation of proteins and minerals and the rheological and textural properties of processed cheese (PC) prepared from Gouda cheese ripened for 30-150 d at 8°C was studied. The solubilisation of individual caseins and Ca and the maximum loss tangent during temperature sweeps of PC made from Gouda cheese increased, while hardness of PC decreased with ripening duration of the Gouda cheese. Levels of soluble Ca in PC increased with increasing concentration of TSC and SHMP, but decreased with increasing concentration of DSP. The solubilisation of casein and Ca due to ripening of Gouda cheese used for manufacturing PC could explain the changes in texture and loss tangent of PC. The results suggest that DSP, TSC or SHMP in PC formulation can form insoluble Ca-phosphate, soluble Ca-citrate or insoluble casein-Ca-HMP complexes, respectively, that influence casein solubilisation differently and together with levels of residual intact casein determine the functional attributes of PC.
Topics: Cheese; Food Handling; Caseins; Solubility; Rheology; Citrates; Calcium; Phosphates; Hardness; Time Factors; Calcium Phosphates
PubMed: 38945567
DOI: 10.1016/j.foodres.2024.114587 -
Journal of Global Antimicrobial... Jun 2024The use of cephalosporins combined with clavulanate for the treatment of ESBL-harbouring Enterobacteriaceae has been scarcely described. We aimed to describe the effect...
OBJECTIVES
The use of cephalosporins combined with clavulanate for the treatment of ESBL-harbouring Enterobacteriaceae has been scarcely described. We aimed to describe the effect of different concentrations of clavulanate in the MIC of cefixime and ceftibuten of ESBL-producing Escherichia coli and Klebsiella pneumoniae.
METHODS
ESBL-producing E. coli and K. pneumoniae isolates were studied. Fixed concentrations of cefixime and ceftibuten (ranges of 32-0.25 and 64-0.5 ng/ml, respectively) were used. Combinations of cefixime/clavulanate and ceftibuten/clavulanate in different ratios (1:0, 1:1, 2:1, 4:1, 8:1, 16:1, 32:1) were tested. MIC were determined by broth microdilution.
RESULTS
A total of 6 ESBL-producing E. coli, 6 ESBL-producing K. pneumoniae and 2 control E. coli were tested. When different quantities of clavulanate were added to cefixime and ceftibuten, greater than two-fold decreases in the MIC were observed. When testing the 1:1 cefixime/clavulanate ratio, 10/12 isolates were susceptible. When the ratios 2:1, 4:1, 8:1, and 16:1 were tested, susceptibility was noted for 9/12, 8/12, 4/12, and 5/12 isolates, respectively. Only 2/12 K. pneumoniae isolates were susceptible when the ratio 32:1 was tested. When testing ceftibuten/clavulanate, all isolates remained susceptible across all experiments.
CONCLUSIONS
Clavulanic acid has a favourable effect in reducing the MIC of cefixime and ceftibuten in isolates of ESBL-producing E. coli and K. pneumoniae. Combining clavulanate with ceftibuten or cefixime could be a useful treatment strategy.
PubMed: 38945364
DOI: 10.1016/j.jgar.2024.06.008 -
Journal of Dairy Science Jun 2024The aims of this research were to evaluate how prolonged feeding of a high-concentrate diet affects the ruminal degradation kinetics of fiber and starch, and to evaluate...
The aims of this research were to evaluate how prolonged feeding of a high-concentrate diet affects the ruminal degradation kinetics of fiber and starch, and to evaluate the effects of the high-concentrate diet on apparent total-tract nutrient digestibility in dairy cows. We also investigated the dysbiotic effects and the remodeling of the hindgut microbiome with prolonged high-concentrate feeding. Nine Holstein cows were used in 2 experimental periods; in each period, cows were first fed a 100% forage diet (Forage) for 1 week, followed by stepwise adaptation during one week to a high-concentrate diet (HC; 65% concentrate), which was then fed for 4 consecutive weeks. The kinetics of in situ ruminal degradability of grass silage (DM and NDF), corn grain and wheat grain (DM and starch) as well as the apparent total-tract nutrient digestibility were evaluated in the Forage feeding and in wk 4 on HC. Whereas the hindgut microbiome and fermentation profile were evaluated on a weekly basis. Regarding the in situ ruminal degradability due to grain type, the rate of degradation of the potentially degradable fraction of the grain and the effective rumen degradability of wheat grain were greater compared with corn grain. The in situ ruminal degradability of NDF decreased with the HC diet. However, the apparent total-tract digestibility of crude protein, fat, starch, NDF, ADF and NFC increased with HC compared with Forage feeding. In addition, the HC diet increased the concentration of short-chain fatty acids in the hindgut, lowering fecal pH by 0.6 units, which correlated positively with microbial α diversity. This resulted in lower α diversity with HC; however, α diversity (number of ASVs) showed recovery in wk 3 and 4 on HC; in addition, microbial β diversity did not change from wk 2 on HC onwards. Two microbial enterotypes were identified: one for the Forage diet with abundance of Akkermansia and Anaerosporobacter, and another enterotype for the HC diet with enrichment in Bifidobacterium and Butyrivibrio. Overall, results show that major microbial shifts and hindgut dysbiosis occurred in wk 1 on HC. However, the hindgut microbial diversity of cows adapted after 3 weeks of consuming the starch-rich ration. Thus, feeding HC diet impaired fiber degradation in the rumen, but increased apparent total-tract nutrient digestibility. Likely, the forage diet contained less digestible NDF than the HC diet due to greater inclusion of forages with lower NDF digestibility and lower inclusion of more digestible non-forage NDF. Results also suggest that the adaptation of the hindgut microbial diversity of cows observed 3 weeks after the diet transition likely contributed to enhance total-tract nutrient digestibility.
PubMed: 38945264
DOI: 10.3168/jds.2024-24919 -
Poultry Science Jun 2024This study aimed to investigate how various selenium sources affect the intestinal health of broiler chickens. A total of 384, one-day-old Arbor Acres broilers were...
This study aimed to investigate how various selenium sources affect the intestinal health of broiler chickens. A total of 384, one-day-old Arbor Acres broilers were weighed and randomly allocated to four treatment groups. The control diet was a basal diet added with: 0.2 mg/kg Sodium Selenite (SS-control), 0.2 mg/kg Selenium nano-particles (Nano-Se), 0.2 mg/kg Selenomethionine (SeMet), and 0.2 mg/kg Selenocysteine (Sec) as the treatments. The results indicated that Nano-Se and SeMet were effective in enhancing the villus height (VH) and the villus height/crypt depth ratio (VH/CD) in the jejunum compared to (SS) (P < 0.05). The inclusion of Nano-Se into the diets increased the mRNA levels of zonula occluden-1 (ZO-1), ZO-2, Occludin, Claudin-1, and Claudin-3 compared to the SS diet (P < 0.05). The SeMet increased the levels of ZO-1 and Claudin-3 compared to the SS (P < 0.05). Moreover, SeMet upregulated the marker genes of intestinal enteroendocrine cells, stem cells, and epithelial cells compared to the SS diet (P < 0.05). However, supplementation of Nano-Se reduced the mRNA levels of interleukin 1β (IL-1β), and IL-8 and the concentration of reactive oxygen species (ROS) in the jejunum compared to the SS (P < 0.05). The Nano-Se and SeMet also increased the protein levels of CAT and SOD compared to the SS and Sec diet (P < 0.05). The number of the goblet cells and Mucin-2 (Muc2) levels were the highest in the Nano-Se group (P < 0.05). The protein expression levels of goblet cell differentiation regulator (v-myc avian myelocytomatosis viral oncogene homolog, c-Myc) were highest in the Nano-Se compared to the SS diet (P < 0.05). The Nano-Se decreased the mRNA and protein levels of NLRP3 signaling pathway-related genes compared to the SS diet (P < 0.05). In conclusion, our study demonstrated that Nano-Se and SeMet are better at improving the intestinal health of 21-day-old broilers. Additionally, Nano-Se demonstrated superior antioxidant and anti-inflammatory effects, promoting the development of intestinal goblet cells by modifying the NLRP3 signaling pathway.
PubMed: 38945002
DOI: 10.1016/j.psj.2024.103958