Effect of Acute and Chronic Ingestion of Exogenous Ketone Supplements on Blood Pressure: A Systematic Review and Meta-Analysis.

Exogenous ketone supplements have been suggested to have potential cardiovascular benefits, but their overall effect on blood pressure is unclear. Our objective was to perform a systematic review and meta-analysis on the effects of exogenous ketone supplements on blood pressure (BP) and concomitant changes in resting heart rate (HR). Five databases were searched on January 27th, 2023, for randomized and non-randomized studies. A random-effects model meta-analysis was performed including all studies jointly and separately for acute and chronic ingestion of ketone supplements. Out of 4012 studies identified in the search, 4 acute and 6 chronic studies with n = 187 participants were included. Pooled results (n = 10) showed no change in systolic (SMD [95% CI]= -0.14 [-0.40; 0.11]; I2= 30%; p = 0.17) or diastolic BP (-0.12 [-0.30; 0.05]; I2= 0%; p = 0.69), with a potential tendency observed toward increased resting heart rate (0.17 [-0.14; 0.47]; I2= 40%; p = 0.10). Similar results for systolic and diastolic BP were observed when assessing separately the effect of acute and chronic ingestion of ketone supplements (p ≥ 0.33). Supplement dosage was found to modulate the increase in resting heart rate (0.019 ± 0.006; p = 0.013; R2=100%), suggesting that higher supplement doses lead to a higher resting heart rate. Based on currently available data, acute or prolonged ingestion of ketone supplements does not seem to modulate BP. However, a tendency for HR to increase after acute ingestion was observed, particularly with higher doses. Higher quality studies with appropriate standardized measurements are needed to confirm these results.

The Effect of Exercise Modalities on Walking Capacity in Patients With Intermittent Claudication: A NETWORK META-ANALYSIS.

INTRODUCTION: Despite extensive research on the effect of supervised exercise therapy on walking performance in patients with symptomatic peripheral arterial disease (PAD), it remains unclear which training modality provides the greatest improvement in walking capacity. The objective of this study was to compare the effect of different types of supervised exercise therapy on walking capacity in individuals with symptomatic PAD. METHODS: A random-effect network meta-analysis was performed. The following databases were searched from January 1966 to April 2021: SPORTDiscus, CINAHL, MEDLINE, AMED, Academic Search Complete and, Scopus. Trials had to include at least one type of supervised exercise therapy for patients with symptomatic PAD, with an intervention lasting ≥2 wk with ≥5 training sessions, and an objective measure of walking capacity. RESULTS: Eighteen studies were included for a total sample of 1135 participants. Interventions duration ranged from 6-24 wk and included aerobic exercise (treadmill walking, ergometer, and Nordic walking), resistance training (lower and/or upper body), a combination of both, and underwater exercise. Results showed that combined training improved treadmill walking capacity to a comparable extent to aerobic walking (+122.0 [24.2-219.8] m vs +106.8 [34.2-179.4] m), but with a larger effect size (1.20 [0.50-1.90] vs 0.67 [0.22-1.11]). Similar results were observed for the 6-min walk distance, with combined training being the most promising modality (+57.3 [16.2-98.5] m), followed by underwater training (+56.5 [22.4-90.5] m) and aerobic walking (+39.0 [12.8-65.1] m). CONCLUSION: While not statistically superior to aerobic walking, combined exercise seems to be the most promising training modality. Aerobic walking and underwater training also improved walking capacity for patients with symptomatic PAD.

The Influence of Family History of Type 2 Diabetes on Metabolism during Submaximal Aerobic Exercise and in the Recovery Period in Postmenopausal Women.

Aging and family history of type 2 diabetes (T2D) are known risk factors of T2D. Younger first-degree relatives (FDR) of T2D patients have shown early metabolic alterations, which could limit exercise's ability to prevent T2D. Thus, the objective was to determine whether exercise metabolism was altered during submaximal exercise in FDR postmenopausal women. Nineteen inactive postmenopausal women (control: 10, FDR: 9) aged 60 to 75 years old underwent an incremental test on a cycle ergometer with intensity ranging from 40 to 70% of peak power output. Participants consumed 50 mg of 13C-palmitate 2 h before the test. At the end of each stage, glucose, lactate, glycerol, non-esterified fatty acids and 13C-palmitate were measured in plasma, and 13CO2 was measured in breath samples. Gas exchanges and heart rate were both monitored continuously. There were no between-group differences in substrate oxidation, plasma substrate concentrations or 13C recovered in plasma or breath. Interestingly, despite exercising at a similar relative intensity to control, FDR were consistently at a lower percentage of heart rate reserve. Overall, substrate plasma concentration and oxidation are not affected by family history of T2D in postmenopausal women and therefore not a participating mechanism in the altered response to exercise previously reported. More studies are required to better understand the mechanisms involved in this response.

Validation of a Modified Version of Actero™ Salmonella Enrichment Media for Rapid Detection of Salmonella spp. in Environmental and Food Samples.

BACKGROUND: Actero™ Salmonella Enrichment Media1 (Actero™ Salmonella) is a culture broth developed to recover Salmonella spp. from foods and environmental surfaces. Performance of Actero™ Salmonella broth has already been assessed and validated (AOAC Performance Tested MethodSM 041403) for the detection of Salmonella spp. in various foods, feeds and environmental samples. OBJECTIVE: This study aimed to validate the performance of a modified version of Actero™ Salmonella broth by incorporating one of the two liquid supplements into the powdered formula. METHODS: Inclusivity, exclusivity, stability, and lot-to-lot studies were carried out. Raw ground beef, chicken carcass rinse, dry pet food and stainless steel samples were enriched for 14-20 h at 35-39°C and analyzed using real-time PCR assay as well as by direct plating. RESULTS: The Probability of Detection assay confirmed the equivalent performance of the alternative methods as compared to the reference methods. All Salmonella strains, except Salmonella II : 57: z29:-, were able to grow in Actero™ Salmonella broth. One-half of the non-target strains did not grow in Actero™ Salmonella broth, whereas the atypical for Salmonella growth was observed for other non-target microorganisms subsequently plated onto selective and differential agars. Lot-to-lot consistency was demonstrated for three consecutively manufactured lots of the broth. The liquid broth was proven to be stable at 4°C for up to 9 weeks of storage. CONCLUSIONS AND HIGHLIGHTS: The incorporation of one of the two specific supplements into a powdered formula of Actero™ Salmonella broth made it more convenient to use without compromising the performance and accuracy.

Validation of FoodChek™ - Salmonella for Rapid Detection of Salmonella in Eggs, Derivative Products, and the Environment.

The FoodChek™ - Salmonella assay is an immunomagnetic lateral flow assay for the rapid detection (shorter than 24 h) of the most frequently isolated Salmonella (groups B-E) in eggs, egg-derivative products, and environmental surfaces. The FoodChek - Salmonella assay correctly identified 99.6% (239/240) of the samples tested in the matrix studied, and the statistical analysis of the method comparison study results demonstrated that it performs as well as U.S. culture-based reference methods. Ninety-nine percent of the 103 Salmonella strains tested belonging to serogroups B-E were detected during the inclusivity study. Concerning the exclusivity, 31 nontarget strains were tested. No cross-reactivity was observed in FoodChek - Salmonella assay enrichment conditions. In addition, the assay shows strong robustness, good stability, and consistency among lots. The present study proves that the assay is an effective tool for the rapid detection of Salmonella spp. in whole liquid eggs, liquid egg white (liquid egg albumen), shell eggs, dried whole eggs, dried egg yolks, and environmental surfaces as stainless steel, plastic, rubber, ceramic tiles, and sealed concrete.

Constitutive regulatory activity of an evolutionarily excluded riboswitch variant.

The exquisite specificity of the adenine-responsive riboswitch toward its cognate metabolite has been shown to arise from the formation of a Watson-Crick interaction between the adenine ligand and residue U65. A recent crystal structure of a U65C adenine aptamer variant has provided a rationale for the phylogenetic conservation observed at position 39 for purine aptamers. The G39-C65 variant adopts a compact ligand-free structure in which G39 is accommodated by the ligand binding site and is base-paired to the cytosine at position 65. Here, we demonstrate using a combination of biochemical and biophysical techniques that the G39-C65 base pair not only severely impairs ligand binding but also disrupts the functioning of the riboswitch in vivo by constitutively activating gene expression. Folding studies using single-molecule FRET revealed that the G39-C65 variant displays a low level of dynamic heterogeneity, a feature reminiscent of ligand-bound wild-type complexes. A restricted conformational freedom together with an ability to significantly fold in monovalent ions are exclusive to the G39-C65 variant. This work provides a mechanistic framework to rationalize the evolutionary exclusion of certain nucleotide combinations in favor of sequences that preserve ligand binding and gene regulation functionalities.

Folding of the adenine riboswitch.

The pbuE adenine riboswitch undergoes metal ion-dependent folding that involves a loop-loop interaction. Binding of 2-aminopurine to the aptamer domain strongly correlates with the ability of the loops to interact, and single-molecule FRET studies reveal that folding proceeds via a discrete intermediate. Folding occurs in the absence of adenine ligand, but ligand binding stabilizes the folded structure by increasing the folding rate and decreasing the unfolding rate, and it lowers the magnesium ion concentration required to promote the loop-loop interaction. Individual aptamer molecules exhibit great heterogeneity in folding and unfolding rates, but this is reduced in the presence of adenine. In the full riboswitch, the adenine binding domain fails to fold because of conformational competition by the terminator stem. Thus, riboswitch function should depend on the relative rates of ligand binding and the transcriptional process.