Hydrolysis-dominated catalytic system: Hydrogen-free hydrogenolysis of lignin from Pd-MoOx/TiO2

Lignin is continuously investigated by various techniques for valorization due to its high content of oxygen-containing functional groups. Catalytic systems employing hydrolysis‑hydrogenolysis, leveraging the synergistic effect of redox metal sites and acid sites, exhibit efficient degradation of lignin. The predominance of either hydrolysis or hydrogenolysis reactions hinges upon the relative activity of acid and metal sites, as well as the intensity of the reductive atmosphere. In this study, the Pd-MoOx/TiO2 catalyst was found to primarily catalyze hydrolysis in the lignin depolymerization process, attributed to the abundance of moderate acidic sites on Pd and the redox-assisted catalysis of MoOx under inert conditions. After subjecting the reaction to 240 °C for 30 h, a yield of 48.22 wt% of total phenolic monomers, with 5.90 wt% consisting of diphenols, was achieved. Investigation into the conversion of 4-propylguaiacol (4-PG), a major depolymerized monomer of corncob lignin, revealed the production of ketone intermediates, a phenomenon closely linked to the unique properties of MoOx. Dehydrogenation of the propyl is a key step in initiating the reaction, and 4-PG could be almost completely transformed, accompanied by an over 97 % of 4-propylcatechol selectivity. This distinctive system lays a new theoretical groundwork for the eco-friendly valorization of lignin.

Copper(I)-Catalyzed Asymmetric Allylation of Ketones with 2-Aza-1,4-Dienes

Catalytic asymmetric allylation of ketones under proton-transfer conditions is a challenging issue due to the limited pronucleophiles and the electrophilic inertness of ketones. Herein, a copper(I)-catalyzed asymmetric allylation of ketones with 2-aza-1,4-dienes (N-allyl-1,1-diphenylmethanimines) is disclosed, which affords a series of functionalized homoallyl tertiary alcohols in high to excellent enantioselectivity. Interestingly, N-allyl-1,1-diphenylmethanimines work as synthetic equivalents of propanals. Upon the acidic workup, a formal asymmetric β-addition of propanals to ketones is achieved. An investigation on KIE effect indicates that the deprotonation of N-allyl-1,1-diphenylmethanimines is the rate-determining step, which generates nucleophilic allyl copper(I) species. Finally, the synthetic utility of the present method is demonstrated by the asymmetric synthesis of (R)-boivinianin A and (R)-gossonorol.

Metabolic shift toward ketosis in asocial cavefish increases social-like affinity

BACKGROUND

Social affinity and collective behavior are nearly ubiquitous in the animal kingdom, but many lineages feature evolutionarily asocial species. These solitary species may have evolved to conserve energy in food-sparse environments. However, the mechanism by which metabolic shifts regulate social affinity is not well investigated.

RESULTS

In this study, we used the Mexican tetra (Astyanax mexicanus), which features riverine sighted surface (surface fish) and cave-dwelling populations (cavefish), to address the impact of metabolic shifts on asociality and other cave-associated behaviors in cavefish, including repetitive turning, sleeplessness, swimming longer distances, and enhanced foraging behavior. After 1 month of ketosis-inducing ketogenic diet feeding, asocial cavefish exhibited significantly higher social affinity, whereas social affinity regressed in cavefish fed the standard diet. The ketogenic diet also reduced repetitive turning and swimming in cavefish. No major behavioral shifts were found regarding sleeplessness and foraging behavior, suggesting that other evolved behaviors are not largely regulated by ketosis. We further examined the effects of the ketogenic diet via supplementation with exogenous ketone bodies, revealing that ketone bodies are pivotal molecules positively associated with social affinity.

CONCLUSIONS

Our study indicated that fish that evolved to be asocial remain capable of exhibiting social affinity under ketosis, possibly linking the seasonal food availability and sociality.

Recognizing and Managing a Metabolic Crisis

In some relatively common inborn errors of metabolism there can be the accumulation of toxic compounds including ammonia and organic acids such as lactate and ketoacids, as well as energy deficits at the cellular level. The clinical presentation is often referred to as a metabolic emergency or crisis. Fasting and illness can result in encephalopathy within hours, and without appropriate recognition and intervention, the outcome may be permanent disability or death. This review outlines easy and readily available means of recognizing and diagnosing a metabolic emergency as well as general guidelines for management. Disease-specific interventions focus on parenteral nutrition to reverse catabolism, toxin removal strategies, and vitamin/nutrition supplementation.

Intermolecular Metal-Catalyzed C‒C Coupling of Unactivated Alcohols or Aldehydes for Convergent Ketone Construction beyond Premetalated Reagents

Intermolecular metal-catalyzed C‒C couplings of unactivated primary alcohols or aldehydes to form ketones are catalogued. Reactions are classified on the basis of pronucleophile. Protocols involving premetalated reagents or reactants that incorporate directing groups are not covered. These methods represent an emerging alternative to classical multi-step protocols for ketone construction that exploit premetalated reagents, and/or steps devoted to redox manipulations and carboxylic acid derivatization.

Ketolysis is required for the proper development and function of the somatosensory nervous system

Ketogenic diets are emerging as protective interventions in preclinical and clinical models of somatosensory nervous system disorders. Additionally, dysregulation of succinyl-CoA 3-oxoacid CoA-transferase 1 (SCOT, encoded by Oxct1), the fate-committing enzyme in mitochondrial ketolysis, has recently been described in Friedreich's ataxia and amyotrophic lateral sclerosis. However, the contribution of ketone metabolism in the normal development and function of the somatosensory nervous system remains poorly characterized. We generated sensory neuron-specific, Advillin-Cre knockout of SCOT (Adv-KO-SCOT) mice and characterized the structure and function of their somatosensory system. We used histological techniques to assess sensory neuronal populations, myelination, and skin and spinal dorsal horn innervation. We also examined cutaneous and proprioceptive sensory behaviors with the von Frey test, radiant heat assay, rotarod, and grid-walk tests. Adv-KO-SCOT mice exhibited myelination deficits, altered morphology of putative Aδ soma from the dorsal root ganglion, reduced cutaneous innervation, and abnormal innervation of the spinal dorsal horn compared to wildtype mice. Synapsin 1-Cre-driven knockout of Oxct1 confirmed deficits in epidermal innervation following a loss of ketone oxidation. Loss of peripheral axonal ketolysis was further associated with proprioceptive deficits, yet Adv-KO-SCOT mice did not exhibit drastically altered cutaneous mechanical and thermal thresholds. Knockout of Oxct1 in peripheral sensory neurons resulted in histological abnormalities and severe proprioceptive deficits in mice. We conclude that ketone metabolism is essential for the development of the somatosensory nervous system. These findings also suggest that decreased ketone oxidation in the somatosensory nervous system may explain the neurological symptoms of Friedreich's ataxia.

Effects of ketone supplements on blood β-hydroxybutyrate, glucose and insulin: A systematic review and three-level meta-analysis

BACKGROUND

Effects of ketone supplements as well as relevant dose-response relationships and time effects on blood β-hydroxybutyrate (BHB), glucose and insulin are controversial.

OBJECTIVE

This study aimed to summarize the existing evidence and synthesize the results, and demonstrate underlying dose-response relationships as well as sustained time effects.

METHODS

Medline, Web of Science, Embase, and Cochrane Central Register of Controlled Trials were searched for relevant randomized crossover/parallel studies published until 25th November 2022. Three-level meta-analysis compared the acute effects of exogenous ketone supplementation and placebo in regulating blood parameters, with Hedge's g used as measure of effect size. Effects of potential moderators were explored through multilevel regression models. Dose-response and time-effect models were established via fractional polynomial regression.

RESULTS

The meta-analysis with 327 data points from 30 studies (408 participants) indicated that exogenous ketones led to a significant increase in blood BHB (Hedge's g = 1.4994, 95% CI [1.2648, 1.7340]), reduction in glucose (Hedge's g = -0.3796, 95% CI [-0.4550, -0.3041]), and elevation in insulin of non-athlete healthy population (Hedge's g = 0.1214, 95%CI [0.0582, 0.3011]), as well as insignificant change in insulin of obesity and prediabetes. Nonlinear dose-response relationship between ketone dosage and blood parameter change was observed in some time intervals for BHB (30-60 min; >120 min) and insulin (30-60 min; 90-120 min), with linear relationship observed for glucose (>120 min). Nonlinear associations between time and blood parameter change were found in BHB (>550 mg/kg) and glucose (450-550 mg/kg), with linear relationship observed in BHB (≤250 mg/kg) and insulin (350-550 mg/kg).

CONCLUSION

Dose-response relationships and sustained time effects were observed in BHB, glucose and insulin following ketone supplementation. Glucose-lowering effect without increasing insulin load among population of obesity and prediabetes was of remarkable clinical implication.

REGISTRY AND REGISTRY NUMBER

PROSPERO (CRD42022360620).

Regional brain glucose metabolism is differentially affected by ketogenic diet: a human semiquantitative positron emission tomography

PURPOSE

Ketogenic diet (KD) is recommended to avoid intense [18F]FDG myocardial physiologic uptake in PET imaging. Neuroprotective and anti-seizure effects of KD have been suggested, but their mechanisms remain to be elucidated. This [18F]FDG PET study aims to evaluate the effect of KD on glucose brain metabolism.

METHOD

Subjects who underwent KD prior to whole-body and brain [18F]FDG PET between January 2019 and December 2020 in our department for suspected endocarditis were retrospectively included. Myocardial glucose suppression (MGS) on whole-body PET was analyzed. Patients with brain abnormalities were excluded. Thirty-four subjects with MGS (mean age: 61.8 ± 17.2 years) were included in the KD population, and 14 subjects without MGS were considered for a partial KD group (mean age: 62.3 ± 15.1 years). Brain SUVmax was first compared between these two KD groups to determine possible global uptake difference. Semiquantitative voxel-based intergroup analyses were secondarily performed to determine possible inter-regional differences by comparing KD groups with and without MGS, separately, to 27 healthy subjects fasting for at least 6 h (mean age of 62.4 ± 10.9 years), and KD groups between them (p-voxel < 0.001, and p-cluster < 0.05, FWE-corrected).

RESULTS

A 20% lower brain SUVmax was found in subjects under KD with MGS in comparison to those without MGS (Student's t-test, p = 0.02). Whole-brain voxel-based intergroup analysis revealed that patients under KD with and without MGS had relative hypermetabolism of limbic regions including medial temporal cortices and cerebellum lobes and relative hypometabolism of bilateral posterior regions (occipital), without significant difference between them.

CONCLUSION

KD globally reduces brain glucose metabolism but with regional differences, requiring special attention to clinical interpretation. On a pathophysiological perspective, these findings could help understand underlying neurological effects of KD through possible decrease of oxidative stress in posterior regions and functional compensation in the limbic regions.

Ketone ester supplementation suppresses cardiac inflammation and improves cardiac energetics in a swine model of acute myocardial infarction

BACKGROUND

Myocardial infarction (MI) is a major risk factor for the development of heart failure with reduce ejection fraction (HFrEF). While previous studies have focused on HFrEF, the cardiovascular effects of ketone bodies in acute MI are unclear. We examined the effects of oral ketone supplementation as a potential treatment strategy in a swine acute MI model.

METHODS

Farm pigs underwent percutaneous balloon occlusion of the LAD for 80 min followed by 72 h reperfusion period. Oral ketone ester or vehicle was administered during reperfusion and continued during the follow-up period.

RESULTS

Oral KE supplementation induced ketonemia 2-3 mmol/l within 30 min after ingestion. KE increased ketone (βHB) extraction in healthy hearts without affecting glucose and fatty acid (FA) consumption. During reperfusion, the MI hearts consumed less FA with no change in glucose consumption, whereas hearts from MI-KE-fed animals consumed more βHB and FA, as well as improved myocardial ATP production. A significant elevation of infarct T2 values indicative of inflammation was found only in untreated MI group compared to sham. Concordantly, cardiac expression of inflammatory markers, oxidative stress, and apoptosis were reduced by KE. RNA-seq analysis identified differentially expressed genes related to mitochondrial energy metabolism and inflammation.

CONCLUSIONS

Oral KE supplementation induced ketosis and enhanced myocardial βHB extraction in both healthy and infarcted hearts. Acute oral supplementation with KE favorably altered cardiac substrate uptake and utilization, improved cardiac ATP levels, and reduced cardiac inflammation following MI.

Exogenous ketosis increases circulating dopamine concentration and maintains mental alertness in ultra-endurance exercise

Exogenous ketosis can improve psychocognitive functioning during exercise as well as stimulate postexercise muscular recovery. Therefore, we hypothesized that ketone ester (KE) supplementation can counteract the decline in psychocognitive functioning during ultra-endurance exercise and stimulate muscular recovery. Eighteen recreational runners participated in a full 100km trail run (RUN, n=8), or ran to premature exhaustion (80km: n=6; 60km: n=4). Before (25g), during (25g·h^-1), and after (5*25g in 24h) RUN they received ketone ester (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (KE, n=9) supplements or a non-caloric placebo (CON, n=9). Blood samples and muscle biopsies were taken, and mental alertness was assessed by a psychocognitive test battery at different times before, during, and up to 36h after RUN. Compared with CON (<0.3 mM), in KE blood D-ß-hydroxybutyrate concentration was consistently elevated to ~2-3 mM during RUN. In CON, RUN increased visual reaction times from 353±53 to 419±54ms, and movement execution times from 174±47 to 245±64ms. But this effect was fully negated by KE (p<0.05). Plasma dopamine concentrations doubled in KE during RUN but remained stable in CON, resulting in higher concentrations after RUN in KE (4.1±1.7 nM) than in CON (2.4±0.8 nM, p=0.048). KE also inhibited muscular infiltration of macrophages and suppressed AMPK phosphorylation status until 36h post exercise (p<0.05 KE vs. CON). In conclusion, KE increases circulating dopamine concentration and improves mental alertness, as well as improves postexercise muscular inflammation in ultra-endurance exercise.

A Catalytic Method for the Enantioselective Synthesis of α-Quaternary Ketones, α-Ketoesters and Aldehydes

A practical method for the efficient and enantioselective preparation of versatile ketones and aldehydes that contain an α-quaternary stereocenter is described. Reactions utilize simple carboxylic acid or ester starting materials, a monodentate chiral phosphine, and afford a variety of aryl, alkenyl, alkynyl, and alkyl-substituted ketone and aldehyde products in 25-94 % yield and 90 : 10 to >99 : 1 enantiomeric ratio. Reactions proceed by acyl substitution with in situ formed chiral allylic nucleophiles, and display selectivity and conversion dependence on a protic additive. The utility of the approach is demonstrated through several product transformations.

Leaf cuticular waxes of wild-type Welsh onion (Allium fistulosum L.) and a wax-deficient mutant: Compounds with terminal and mid-chain functionalities

Plant cuticles cover aerial organs to limit non-stomatal water loss and protect against insects and pathogens. Cuticles contain complex mixtures of fatty acid-derived waxes, with various chain lengths and diverse functional groups. To further our understanding of the chemical diversity and biosynthesis of these compounds, this study investigated leaf cuticular waxes of Welsh onion (Allium fistulosum L.) wild type and a wax-deficient mutant. Leaf waxes were extracted with chloroform, separated using thin layer chromatography (TLC), and analyzed using gas chromatography-mass spectrometry (GC-MS). The extracts contained typical wax compound classes found in nearly all plant lineages but also two uncommon compound classes. Analyses of characteristic MS fragmentation patterns followed by comparisons with synthetic standards identified the latter as very-long-chain ketones and primary ketols. The ketols were minor compounds, with chain lengths ranging from C₂₈ to C₃₂ and carbonyls mainly on C-18 and C-20 in wild type wax, and a C₂₈ chain with C-16 carbonyl in the mutant. The ketones made up 70% of total wax in the wild type, consisting mainly of C₃₁ isomers with carbonyl group on C-14 or C-16. In contrast, the mutant wax comprised only 4% ketones, with chain lengths C₂₇ and C₂₉ and carbonyls predominantly on C-12 and C-14, respectively. A two-carbon homolog shift between wild type and mutant was also observed in the primary alcohols (a major wax compound class), whilst alkanes exhibited a four-carbon shift. Overall, the compositional data shed light on possible biosynthetic pathways to wax ketones that can be tested in future studies.

Hyperketonemia: A Marker of Disease, a Sign of a High-Producing Dairy Cow, or Both?

This review covers the history and nomenclature of ketosis, the source and use of ketones in transition cows, and the controversial role of hyperketonemia's association with health and production outcomes in dairy cows. With the goal of assisting veterinarians with on-farm diagnostic and treatment methods, the authors present current and evolving means of direct and indirect hyperketonemia detection as well as a summary of treatment modalities and their efficacy. They encourage veterinarians to include hyperketonemia testing as part of their routine physical examinations and contemplate day in milk at hyperketonemia diagnosis when designing treatment and management strategies.

ALSUntangled #63: ketogenic diets

ALSUntangled reviews alternative and off label treatments with a goal of helping patients make more informed decisions about them. Here we review ketogenic diets. We shows that these have plausible mechanisms, including augmenting cellular energy balance and reducing excitotoxicity, neuroinflammation and oxidative stress. We review a mouse model study, anecdotal reports and trials in ALS and other diseases. We conclude that there is yet not enough data to recommend ketogenic diets for patients with ALS, especially in light of the many side effects these can have.

Toward nutrition improving outcome of critically ill patients: How to interpret recent feeding RCTs?

Although numerous observational studies associated underfeeding with poor outcome, recent randomized controlled trials (RCTs) have shown that early full nutritional support does not benefit critically ill patients and may induce dose-dependent harm. Some researchers have suggested that the absence of benefit in RCTs may be attributed to overrepresentation of patients deemed at low nutritional risk, or to a too low amino acid versus non-protein energy dose in the nutritional formula. However, these hypotheses have not been confirmed by strong evidence. RCTs have not revealed any subgroup benefiting from early full nutritional support, nor benefit from increased amino acid doses or from indirect calorimetry-based energy dosing targeted at 100% of energy expenditure. Mechanistic studies attributed the absence of benefit of early feeding to anabolic resistance and futile catabolism of extra provided amino acids, and to feeding-induced suppression of recovery-enhancing pathways such as autophagy and ketogenesis, which opened perspectives for fasting-mimicking diets and ketone supplementation. Yet, the presence or absence of an anabolic response to feeding cannot be predicted or monitored and likely differs over time and among patients. In the absence of such monitor, the value of indirect calorimetry seems obscure, especially in the acute phase of illness. Until now, large feeding RCTs have focused on interventions that were initiated in the first week of critical illness. There are no large RCTs that investigated the impact of different feeding strategies initiated after the acute phase and continued after discharge from the intensive care unit in patients recovering from critical illness.

Acetoacetate and β-hydroxybutyrate reduce mouse embryo viability via differential metabolic and epigenetic mechanisms

RESEARCH QUESTION

Does the ketone acetoacetate (AcAc) alone, or combined with β-hydroxybutyrate (βOHB), impact mouse embryo development, metabolism, histone acetylation and viability?

DESIGN

Pronucleate mouse oocytes were cultured in vitro in G1/G2 media supplemented with ketones (AcAc or AcAc + βOHB) at concentrations representing those in maternal serum during pregnancy (0.04 mmol/l AcAc, 0.1 mmol/l βOHB), standard diet consumption (0.1 mmol/l AcAc, 0.25 mmol/l βOHB), ketogenic diet consumption (0.8 mmol/l AcAc, 2 mmol/l βOHB) and diabetic ketoacidosis (2 mmol/l AcAc, 4 mmol/l βOHB). Day 5 blastocysts were assessed for cell allocation, glucose metabolism and histone acetylation. Day 4 blastocysts exposed to 0.8 mmol/l AcAc + 2 mmol/l βOHB were transferred to standard-fed recipient females, and E14.5 fetal and placental development assessed.

RESULTS

Exposure to 2 mmol/l AcAc or 0.8 mmol/l AcAc + 2 mmol/l βOHB did not impair blastocyst development, but significantly increased glucose consumption (P = 0.001 each), lowered glycolytic flux (P = 0.01, P < 0.001) and elevated trophectoderm (TE) histone 3 lysine 27 acetylation (H3K27ac; P < 0.001 each) compared with unexposed controls. Preimplantation AcAc + βOHB exposure reduced post-implantation fetal development by 25% (P = 0.037), and delayed female-specific fetal limb development (P = 0.019) and estimated fetal age (P = 0.019) compared with controls.

CONCLUSION

Preimplantation exposure to ketones affects underlying metabolism and histone acetylation in blastocysts that are associated with persistent, female-specific perturbations in fetal development. A periconceptional diet that elevates ketone concentrations may impair human embryonic viability.

Insight into the impacts and mechanisms of ketone stress on the antibiotic resistance in Escherichia coli

Accumulation of toxic organic has posed a substantial pressure on the proliferation of bacterial resistance. While aromatic organics have been demonstrated to enhance the antibiotic resistance in bacteria, no information is yet available on the effects of non-aromatic organics on the variations of bacterial resistance. Here, we investigated the effects of a typical ketone (i.e., methylisobutanone (MIBK)) on the variations of antibiotic resistance in Escherichia coli (E. coli). The results showed that the growth of resistant E. coli under environmental concentration of 50 μg/L MIBK was firstly inhibited as explained by the transient disruption in the cell membrane and then recovered possibly due to the reactive oxygen species. Exposure to 50 μg/L MIBK gradually raised the abundance of representative resistance gene (ampR) in E. coli. In contrast, the high concentration of 50 mg/L MIBK continuously inhibited the growth of resistant E. coli by disrupting cell membrane and notably promoted the proliferation of ampR through enhancing the horizontal transformation and up-regulating the expression of efflux pump gene. These findings provided the first evidence for the evolution of bacterial resistance in response to ketone organics.

Potential Clinical Applications for Continuous Ketone Monitoring in the Hospitalized Patient with Diabetes

PURPOSE OF REVIEW

In this review, the authors discuss potential clinical applications for continuous ketone monitoring (CKM) in a broad continuum of clinical settings from pre-hospital care and the emergency department to acute inpatient management and post-discharge follow-up.

RECENT FINDINGS

Though in its early stages, the concept of a novel continuous ketone sensing technology exerts great potential for use in the detection and hospital management of DKA, namely to overcome diagnostic barriers associated with ketoacidosis in patients with diabetes and obtain real-time BOHB levels, which may be useful in understanding both patients' response to treatment and DKA trajectory. Peri- and intra-operative use of CKM technology can potentially be applied in a number of urgent and elective surgical procedures frequently underwent by patients with diabetes and in the observation of patients during peri-operative fasting. In transitional care management, CKM technology could potentially facilitate patients' safe transition through levels of care, following hospital discharge from a DKA episode. This evaluation of the literature presents the potential advantages of adopting CKM and integrating this technology into the care algorithm of patients at risk for ketoacidosis.

An acetate-independent pathway for isopropanol production via HMG-CoA in Escherichia coli

Isopropanol has a good potential as a new fuel substitution. In the model biosynthesis pathway of isopropanol synthesis, acetoacetyl-CoA is converted to acetoacetate by acetoacetyl-CoA transferases, which requires an acetate molecule as a substrate. Herein, a novel isopropanol synthesis pathway based on mammalian ketone metabolic pathway was developed. In this pathway, acetoacetyl-CoA is condensed with acetyl-CoA to generate 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) by HMG-CoA synthase, and then catalyzed by HMG-CoA lyase to generate acetoacetate. This process is acetate-independent. Under the same experimental system using glycerol as carbon source, the E. coli strain MG::ISOP1 containing the novel pathway produced 11.7 times more isopropanol than the strain MG::ISOP0 containing the model pathway. The pta-ackA knockout mutant strain MG∆pta-ackA::ISOP1, which reduced the conversion of acetyl-CoA to acetate, further increased the production from 76 mg/L to 360 mg/L. In another strategy, knocking out atoDA to block the acetoacetate degradation pathway in strain MG∆atoDA::ISOP1 increased the production to 680 mg/L. By knocking out both of pta-ackA and atoDA, strain MGΔpta-ackAΔatoDA::ISOP1 produced 964 mg/L of isopropanol, which was 12.7 times that of MG::ISOP1. This study indicated that the novel pathway is competent for isopropanol synthesis, and provides a new perspective for biosynthesis of isopropanol.

Non-Noble Metal-Catalyzed Carbonylative Multi-Component Reactions

Carbonylative multi-component reactions (CMCR), having four or more kinds of starting materials, provide an efficient strategy for the preparation of polyfunctional carbonylated compounds. Diverse CMCR utilizing non-noble transition-metal catalysts have been developed. This review summarized and discussed the recent advances in non-noble metal-catalyzed carbonylative multi-component reactions.

Impact of medium-chain triglycerides on gait performance and brain metabolic network in healthy older adults: a double-blind, randomized controlled study

Nutritional supplementation with medium-chain triglycerides (MCTs) has the potential to increase memory function in elderly patients with frailty and dementia. Our aim was to investigate the effects of MCT on cognitive and gait functions and their relationships with focal brain metabolism and functional connectivity even in healthy older adults. Participants were blindly randomized and allocated to two groups: 18 g/day of MCT oil and matching placebo formula (control) administered as a jelly stick (6 g/pack, ingested three times a day). Gait analysis during the 6-m walk test, cognition, brain focal glucose metabolism quantified by ¹⁸F-fluorodeocyglucose positron emission tomography, and magnetic resonance imaging-based functional connectivity were assessed before and after a 3-month intervention. Sixty-three healthy, normal adults (females and males) were included. Compared with the control group, the MCT group showed better balance ability, as represented by the lower Lissajous index (23.1 ± 14.4 vs. 31.3 ± 18.9; P < 0.01), although no time × group interaction was observed in cognitive and other gait parameters. Moreover, MCT led to suppressed glucose metabolism in the right sensorimotor cortex compared with the control (P < 0.001), which was related to improved balance (r = 0.37; P = 0.04) along with increased functional connectivity from the ipsilateral cerebellar hemisphere. In conclusion, a 3-month MCT supplementation improves walking balance by suppressing glucose metabolism, which suggests the involvement of the cerebro-cerebellar network. This may reflect, at least in part, the inverse reaction of the ketogenic switch as a beneficial effect of long-term MCT dietary treatment.

Monitoring of blood glucose levels, ketones and insulin bolus advice using 4SURE products and app-based technology

With more people being diagnosed with diabetes and requiring insulin therapy as they live longer, an increasing number of individuals are needing access to blood and ketone monitoring that is simple to use and provides accurate results. Having access to a bolus advisor is equally important in order for people with diabetes to calculate accurate insulin doses based on the foods that they are eating. The use of app-based technology for healthcare purposes has increased over recent years and now includes the Diabetes:M application that can be used in conjunction with the 4SURE smart meters with no additional cost to the individual.

Catalytic Hydroboration and Reductive Amination of Carbonyl Compounds by HBpin using a Zinc Promoter

In this paper, the chemoselective hydroboration of aldehydes and ketones, catalyzed by Zinc(II) complexes [ k 2 -(PyCH=NR)ZnX 2 ] [R = CPh 3 , X = Cl ( 1 ) and R = Dipp (2,6-diisoropylphenyl) and X = I ( 2 )], in the presence of pinacolborane (HBpin) in ambient temperature and solvent-free conditions, which produced corresponding boronate esters in high yield, is reported. Zinc metal complexes 1 and 2 were derived in 80-90% yield from the reaction of iminopyridine [PyCH=NR] with anhydrous zinc dichloride in dichloromethane at room temperature. The solid-state structures of both zinc complexes were confirmed using X-ray crystallography. Zinc complex 1 was also used as a competent pre-catalyst in the reductive amination of carbonyl compounds with HBpin under mild and solvent-free conditions to afford a high yield (up to 97%) of the corresponding secondary amines. The wider substrate scope of both reactions was explored. Catalytic protocols using zinc as a pre-catalyst demonstrated an atom-economic and green method with diverse substrates bearing excellent functional group tolerance. Computational studies established a plausible mechanism for catalytic hydroboration.

Seasonal changes in problem-solving in wild African striped mice

Innovative problem-solving ability is a predictor of whether animals can successfully cope with environmental changes. These environmental changes can test the limits of animals, for example when energy availability decreases seasonally and, hence, problem-solving performance decreases because less energy is available for cognitive processes. Here, we investigated: (1) how problem-solving performance changed between seasons that differed significantly in food availability; (2) whether these changes were related to environmentally induced physiological changes in blood glucose and ketone levels, indicators of energy availability; and (3) whether individual variation in problem-solving was related to sex differences. We studied 99 free-ranging African striped mice, Rhabdomys pumilio, in the Succulent Karoo, South Africa, 55 during the hot dry summer with low food availability and 44 during the cold wet winter with higher food availability. We measured their problem-solving abilities using a food extraction task and found no seasonal differences in problem-solving success. However, mice solved the problem faster in summer versus winter. In summer, food availability was reduced and blood ketones increased but there was no seasonal difference in blood glucose levels. There were no correlation between problem-solving performance and blood glucose or ketone levels. Overall, more males solved the task than females. It appears that in striped mice cognitive functions can be maintained under harsh environmental conditions.

Supported Palladium-Catalyzed Carbonylative Synthesis of Diaryl Ketones from Aryl Bromides and Arylboronic Acids

A palladium supported on graphitic carbon nitride (Pd/g-C₃ N₄ ) catalyzed carbonylative reaction of aryl bromides and arylboronic acids by has been developed for the construction of diaryl ketones. Using benzene-1,3,5-triyl triformate (TFBen) as the CO source, the reaction proceeded well to give various diaryl ketones in moderate to good yields.

Altered cholesterol homeostasis in critical illness-induced muscle weakness: effect of exogenous 3-hydroxybutyrate

Background

Muscle weakness is a complication of critical illness which hampers recovery. In critically ill mice, supplementation with the ketone body 3-hydroxybutyrate has been shown to improve muscle force and to normalize illness-induced hypocholesterolemia. We hypothesized that altered cholesterol homeostasis is involved in development of critical illness-induced muscle weakness and that this pathway can be affected by 3-hydroxybutyrate.

Methods

In both human critically ill patients and septic mice, the association between circulating cholesterol concentrations and muscle weakness was assessed. In septic mice, the impact of 3-hydroxybutyrate supplementation on cholesterol homeostasis was evaluated with use of tracer technology and through analysis of markers of cholesterol metabolism and downstream pathways.

Results

Serum cholesterol concentrations were lower in weak than in non-weak critically ill patients, and in multivariable analysis adjusting for baseline risk factors, serum cholesterol was inversely correlated with weakness. In septic mice, plasma cholesterol correlated positively with muscle force. In septic mice, exogenous 3-hydroxybutyrate increased plasma cholesterol and altered cholesterol homeostasis, by normalization of plasma mevalonate and elevation of muscular, but not hepatic, expression of cholesterol synthesis genes. In septic mice, tracer technology revealed that 3-hydroxybutyrate was preferentially taken up by muscle and metabolized into cholesterol precursor mevalonate, rather than TCA metabolites. The 3-hydroxybutyrate protection against weakness was not related to ubiquinone or downstream myofiber mitochondrial function, whereas cholesterol content in myofibers was increased.

Conclusions

These findings point to a role for low cholesterol in critical illness-induced muscle weakness and to a protective mechanism-of-action for 3-hydroxybutyrate supplementation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03688-1.

Ingestion of an exogenous ketone monoester improves the glycemic response during oral glucose tolerance test in individuals with impaired glucose tolerance: A cross-over randomized trial

AIMS/INTRODUCTION

As a low-carbohydrate diet and the use of sodium-glucose transporter-2 inhibitors are both known to increase D-beta-hydroxybutyrate levels, the effect of these levels on glucose metabolism has attracted attention. We investigated the acute effects of ketone monoester (KM) ingestion on blood glucose levels during the 75-g oral glucose tolerance test (OGTT) in participants with impaired glucose tolerance.

MATERIALS AND METHODS

Nine Japanese adults aged 48-62 years (4 men, 5 women) with impaired glucose tolerance participated in this study. After participants fasted overnight, we carried out OGTT for 180 min with and without KM ingestion on two separate days in a randomized cross-over design. We compared the area under the curve (AUC) of D-beta-hydroxybutyrate, glucose, insulin, C-peptide, glucagon and free fatty acids during OGTT.

RESULTS

The AUC of D-beta-hydroxybutyrate during OGTT was significantly higher with KM than without KM (KM 5995.3 ± 1257.1 mmol/L·h; without KM 116.1 ± 33.9 mmol/L·h, P < 0.0001), and the AUC of glucose with KM was significantly lower than that without KM (KM 406.6 ± 70.6 mg/dL·h; without KM 483.2 ± 74.3 mg/dL·h, P < 0.0001). This improved glucose excursion was associated with enhanced AUC of insulin during the first half (0-90 min) of OGTT, even though the AUC of C-peptide during this period was unchanged. In contrast, the AUC of insulin, C-peptide, glucagon and free fatty acids during 180 min of OGTT were similar in both conditions.

CONCLUSION

The ingestion of KM decreased the AUC of glucose during 75-g OGTT in Japanese individuals with impaired glucose tolerance, and the mechanism might involve elevated levels of circulating early phase insulin.

Effect of short-term ketogenic diet on end-tidal carbon dioxide

BACKGROUND & AIMS

Previous studies have shown that end-tidal carbon dioxide (EtCO₂) is lower with the presence of supraphysiological ketones as in the case of chronic ketogenic diet (KD) and diabetic ketoacidosis (DKA). This study aimed to determine changes in EtCO₂ upon short term KD.

METHODS

Healthy subjects were screened not to have conditions that exerts abnormal EtCO₂ nor contraindicated for KD. Subjects underwent seven days of KD while the EtCO2 and blood ketone (beta-hydroxybutyrate; β-OHB) parameters were sampled at day zero (t0) and seven (t7) of ketosis respectively. Statistically, the t-test and Pearson's coefficient were conducted to determine the changes and correlation of both parameters.

RESULTS

12 subjects completed the study. The mean score ± standard deviation (SD) for EtCO₂ were 35.08 ± 3.53 and 35.67 ± 3.31 mm Hg for t0 and t7 respectively. The mean score ±SD for β-OHB were 0.07 ± 0.08 and 0.87 ± 0.84 mmol/L for t0 and t7 respectively. There was no significant difference of EtCO₂ between the period of study (p > 0.05) but the β-OHB increased during t7 (p < 0.05). There was also no correlation between the parameters.

CONCLUSIONS

These findings suggest that EtCO₂ may not be utilized to determine short term nutritional ketosis.

Ketones can become the major fuel source for the heart but do not increase cardiac efficiency

AIMS

Ketones have been proposed to be a 'thrifty' fuel for the heart and increasing cardiac ketone oxidation can be cardioprotective. However, it is unclear how much ketone oxidation can contribute to energy production in the heart, nor whether increasing ketone oxidation increases cardiac efficiency. Therefore, our goal was to determine to what extent high levels of the ketone body, β-hydroxybutyrate (βOHB), contributes to cardiac energy production, and whether this influences cardiac efficiency.

METHODS AND RESULTS

Isolated working mice hearts were aerobically perfused with palmitate (0.8 mM or 1.2 mM), glucose (5 mM) and increasing concentrations of βOHB (0, 0.6, 2.0 mM). Subsequently, oxidation of these substrates, cardiac function, and cardiac efficiency were assessed. Increasing βOHB concentrations increased myocardial ketone oxidation rates without affecting glucose or fatty acid oxidation rates where normal physiological levels of glucose (5 mM) and fatty acid (0.8 mM) are present. Notably, ketones became the major fuel source for the heart at 2.0 mM βOHB (at both low or high fatty acid concentrations), with the elevated ketone oxidation rates markedly increasing tricarboxylic acid (TCA) cycle activity, producing a large amount of reducing equivalents and finally, increasing myocardial oxygen consumption. However, the marked increase in ketone oxidation at high concentrations of βOHB was not accompanied by an increase in cardiac work, suggesting that a mismatch between excess reduced equivalents production from ketone oxidation and cardiac adenosine triphosphate production. Consequently, cardiac efficiency decreased when the heart was exposed to higher ketone levels.

CONCLUSIONS

We demonstrate that while ketones can become the major fuel source for the heart, they do not increase cardiac efficiency, which also underscores the importance of recognizing ketones as a major fuel source for the heart in times of starvation, consumption of a ketogenic diet or poorly controlled diabetes.

Real world study of short term efficacy, safety, and tolerability of canagliflozin 100 mg initiation in type 2 diabetes mellitus patients during hot humid Indian summer

BACKGROUND AND AIM

To assess short term (3 months) efficacy, safety, and tolerability of canagliflozin 100 mg among type 2 diabetes mellitus (T2DM) initiated during hot humid Indian summer.

METHODS

A prospective, observational, multi-center study of 300 T2DM patients with inadequate glycemic control (i.e., HbA1c of ≥6.5%) with or without other antihyperglycemic agents (AHA) were enrolled in the study in the month of March. The objective of the study was to assess the efficacy that is changes in glycated hemoglobin (HbA1c), fasting plasma glucose (FPG), post-prandial plasma glucose (PPG), blood pressure (BP), lipid profile, body mass index (BMI) and safety of canagliflozin with regards to genitourinary infection, fall, diabetic keto acidosis (DKA) episodes, blood ketone and beta-hydroxybutyrate levels. All patients were initiated on canagliflozin 100 mg once daily for 12 weeks, irrespective of background medications.

RESULTS

At 12 weeks, a significant reduction was observed in all the glycemic parameters,BMI, BP, total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C). However, a nonsignificant reduction in estimated glomerular filtration rate (eGFR) was observed at 12 weeks. A total of 9 adverse events were reported including 2 episodes of urinary tract infection (UTI) and 4 episodes of genital infection. The blood ketone, beta-hydroxybutyrate levels were found to be within normal limits and no episode of DKA was reported at 12 weeks. None of our patients had reported any volume depletion related adverse events viz. postural hypotension, giddiness etc. CONCLUSION: Canagliflozin 100 mg can be safely initiated in type 2 diabetes patients during hot humid Indian summer, irrespective of background medications and is effective and well tolerated.

Association of higher arterial ketone body ratio (acetoacetate/β-hydroxybutyrate) with relevant nutritional marker in hemodialysis patients

Background

An association of higher levels of β-hydroxybutyrate (β-HB) in serum with greater mortality in hemodialysis (HD) patients has been reported. This study examined the significance of arterial ketone body ratio (AcAc/β-HB), a relevant marker of energy state, in HD patients.

Methods

The levels of arterial AcAc and β-HB, and AcAc/β-HB ratio were determined in 49 HD patients just before undergoing an HD session. Additionally, changes in those levels during the session were examined to investigate their associations with clinical nutritional markers.

Results

Arterial β-HB, but not AcAc, was significantly higher at the baseline in 25 patients with type 2 diabetes mellitus (T2DM) as compared to 24 non-DM patients, with a significant reduction in arterial AcAc/β-HB ratio seen in those with DM. Although the arterial AcAc/β-HB ratio before the HD session was significantly higher in the non-DM group, it did not differ significantly after the session between the groups, indicating a faster rate of β-HB disappearance from circulation in non-DM HD patients during the interdialytic period. Multiple regression analysis, which included age, gender, presence/absence of DM, log HD duration, log β-HB, and log AcAc/β-HB ratio as independent variables, revealed an independent and significant association of log AcAc/ β-HB ratio, but not log β-HB, with serum albumin and uric acid.

Conclusion

We found that a decreased AcAc/β-HB ratio resulting from increased β-HB, but not increased β-HB itself, was a significant factor independently associated with decreased levels of serum albumin and uric acid, known to be related to higher mortality in HD patients. Furthermore, it is possible that higher mortality in DM HD patients can be explained by reduced arterial AcAc/β-HB ratio.

Biological sex and DNA repair deficiency drive Alzheimer's disease via systemic metabolic remodeling and brain mitochondrial dysfunction

Alzheimer's disease (AD) is an incurable neurodegenerative disease that is more prevalent in women. The increased risk of AD in women is not well understood. It is well established that there are sex differences in metabolism and that metabolic alterations are an early component of AD. We utilized a cross-species approach to evaluate conserved metabolic alterations in the serum and brain of human AD subjects, two AD mouse models, a human cell line, and two Caenorhabditis elegans AD strains. We found a mitochondrial complex I-specific impairment in cortical synaptic brain mitochondria in female, but not male, AD mice. In the hippocampus, Polβ haploinsufficiency caused synaptic complex I impairment in male and female mice, demonstrating the critical role of DNA repair in mitochondrial function. In non-synaptic, glial-enriched, mitochondria from the cortex and hippocampus, complex II-dependent respiration increased in female, but not male, AD mice. These results suggested a glial upregulation of fatty acid metabolism to compensate for neuronal glucose hypometabolism in AD. Using an unbiased metabolomics approach, we consistently observed evidence of systemic and brain metabolic remodeling with a shift from glucose to lipid metabolism in humans with AD, and in AD mice. We determined that this metabolic shift is necessary for cellular and organismal survival in C. elegans, and human cell culture AD models. We observed sex-specific, systemic, and brain metabolic alterations in humans with AD, and that these metabolite changes significantly correlate with amyloid and tau pathology. Among the most significant metabolite changes was the accumulation of glucose-6-phosphate in AD, an inhibitor of hexokinase and rate-limiting metabolite for the pentose phosphate pathway (PPP). Overall, we identified novel mechanisms of glycolysis inhibition, PPP, and tricarboxylic acid cycle impairment, and a neuroprotective augmentation of lipid metabolism in AD. These findings support a sex-targeted metabolism-modifying strategy to prevent and treat AD.

Mechanism of the atmospheric chemical transformation of acetylacetone and its implications in night-time second organic aerosol formation

Recently, a high concentration of acetylacetone (AcAc) has been measured in China, and its day-time chemistry with OH reaction has been evaluated. The phenomenon has profound implications in air pollution, human health and climate change. To systematically understand the atmospheric chemistry of AcAc and its role in the atmosphere, the night-time chemistry of AcAc with O₃ and NO₃ radical were investigated in this work in detail using density functional theory. The results show that for O₃- and NO₃-initiated atmospheric oxidation reactions of AcAc, the barrier energies of O₃/NO₃-addition are found to be much lower than those of H-abstraction, suggesting that O₃/NO₃-addition to AcAc is a major contributing pathway in the atmospheric chemical transformation reactions. The total degradation rate constants were calculated to be 2.36 × 10^-17 and 1.92 × 10^-17 cm³ molecule^-1 s^-1 for the O₃- and NO₃-initiated oxidation of AcAc at 298 K, respectively. The half-life of AcAc+O₃ in some polluted areas (such as, Pearl River Delta and Yangtze River Delta) is close to 3 h under typical tropospheric conditions. Due to its short half-life, the ozonolysis of AcAc plays a more significant role in the night-time hours, leading to fast transformations to form primary ozonides (POZs). A prompt, thermal decomposition of POZs occurred to yield methylglyoxal, acetic acid and Criegee intermediates, which mainly contributed to the formation of secondary organic aerosol (SOA). Subsequently, using the high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS), a non-negligible concentration of AcAc was measured in the field observation during the night-time in Nanjing, China. The obtained results reveal that the atmospheric oxidation of AcAc can successively contribute to the formation of SOA under polluted environments regardless of the time (day-time or night-time). This is due to its high reactivity to tropospheric oxidant species (such as, O₃ and NO₃ radicals at night-time).

Myocardial Ketones Metabolism in Heart Failure

Ketone bodies can become a major source of adenosine triphosphate production during stress to maintain bioenergetic homeostasis in the brain, heart, and skeletal muscles. In the normal heart, ketone bodies contribute from 10% to 15% of the cardiac adenosine triphosphate production, although their contribution during pathologic stress is still not well-characterized and currently represents an exciting area of cardiovascular research. This review focuses on the mechanisms that regulate circulating ketone levels under physiologic and pathologic conditions and how this impacts cardiac ketone metabolism. We also review the current understanding of the role of augmented ketone metabolism as an adaptive response in different types and stages of heart failure. This analysis includes the emerging experimental and clinical evidence of the potential favorable effects of boosting ketone metabolism in the failing heart and the possible mechanisms of action through which these interventions may mediate their cardioprotective effects. We also critically appraise the emerging data from animal and human studies which characterize the role of ketones in mediating the cardioprotection established by the new class of antidiabetic drugs, namely sodium-glucose co-transporter inhibitors.

A New Mechanism of Metal-Ligand Cooperative Catalysis in Transfer Hydrogenation of Ketones

We report iridium catalysts IrCl(η⁵-Cp*)(κ²-(2-pyridyl)CH₂NSO₂C₆H₄X) (1-Me, X = CH₃ and 1-F, X = F) for transfer hydrogenation of ketones with 2-propanol that operate by a previously unseen metal-ligand cooperative mechanism. Under the reaction conditions, complexes 1 (1-Me and 1-F) derivatize to a series of catalytic intermediates: Ir(η⁵-Cp*)(κ²-(C₅H₄N)CHNSO₂Ar) (2), IrH(η⁵Cp*)(κ²-(2-pyridyl)CH₂NSO₂Ar) (3), and Ir(η⁵-Cp*)(κ³-(2-pyridyl)CH₂NSO₂Ar) (4). The structures of 1-Me and 4-Me were established by single-crystal X-ray diffraction. A rate-determining, concerted hydrogen transfer step (2 + R₂CHOH ⇄ 3 + R₂CO) is suggested by kinetic isotope effects, Eyring parameters (ΔH ^≠ = 29.1(8) kcal mol^-1 and ΔS ^≠ = -17(19) eu), proton-hydride fidelity, and DFT calculations. According to DFT, a nine-membered cyclic transition state is stabilized by an alcohol molecule that serves as a proton shuttle.

Epigenetics and epilepsy prevention: The therapeutic potential of adenosine and metabolic therapies

Prevention of epilepsy and its progression remains the most urgent need for epilepsy research and therapy development. Novel conceptual advances are required to meaningfully address this fundamental challenge. Maladaptive epigenetic changes, which include methylation of DNA and acetylation of histones - among other mechanisms, are now well recognized to play a functional role in the development of epilepsy and its progression. The methylation hypothesis of epileptogenesis suggests that changes in DNA methylation are implicated in the progression of the disease. In this context, global DNA hypermethylation is particularly associated with chronic epilepsy. Likewise, acetylation changes of histones have been linked to epilepsy development. Clinical as well as experimental evidence demonstrate that epilepsy and its progression can be prevented by metabolic and biochemical manipulations that target previously unrecognized epigenetic functions contributing to epilepsy development and maintenance of the epileptic state. This review will discuss epigenetic mechanisms implicated in epilepsy development as well as metabolic and biochemical interactions thought to drive epileptogenesis. Therefore, metabolic and biochemical mechanisms are identified as novel targets for epilepsy prevention. We will specifically discuss adenosine biochemistry as a novel therapeutic strategy to reconstruct the DNA methylome as antiepileptogenic strategy as well as metabolic mediators, such as beta-hydroxybutyrate, which affect histone acetylation. Finally, metabolic dietary interventions (such as the ketogenic diet) which have the unique potential to prevent epileptogenesis through recently identified epigenetic mechanisms will be reviewed. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.

Non-invasive estimation of the costs of feeding competition in a neotropical primate

A key goal in behavioral ecology is to investigate the factors influencing the access to food resources and energetic condition of females, which are strong predictors of their reproductive success. We aimed to investigate how ecological factors, social factors, and reproductive state are associated with energetic condition in a wild neotropical primate using non-invasive measures. We first assessed and compared urinary C-peptide levels (uCP), the presence of urinary ketones (uKet), and behaviorally assessed energy balance (bEB) in female white-faced capuchin monkeys (Cebus imitator) living in Santa Rosa, Costa Rica. Then, we assessed how these measures were associated with feeding competition, dominance rank, and reproductive state. As predicted, uCP and bEB were positively associated with each other, and bEB was negatively associated with uKet. However, we did not find a relationship between uCP and uKet. Females showed lower uCP and bEB values during periods of intense feeding competition, but this relationship was not dependent on dominance rank. Furthermore, rank was not directly associated with uCP and bEB. Urinary ketones, on the other hand, were only produced in the most adverse conditions: by low-ranking, lactating females during periods of intense feeding competition. Behavioral strategies are assumed to maximize reproductive success and not energetic condition per se, which might explain why rank was not generally associated with energetic condition in our study population. This highlights the importance of considering potential differences between reproductive success and proxies of reproductive success, such as energetic condition or food intake, when investigating predictions of socioecological models.

Enhancement of the serum chloride concentration by administration of sodium-glucose cotransporter-2 inhibitor and its mechanisms and clinical significance in type 2 diabetic patients: a pilot study

BACKGROUND

Chloride is a key electrolyte that regulates the body fluid distribution. Accordingly, manipulating chloride kinetics by selecting a suitable diuretic could be an attractive strategy for correcting body fluid dysregulation. Therefore, this study examined the effects and contributing factors of a sodium-glucose cotransporter-2 inhibitor (SGLT2i) on the serum chloride concentration in type 2 diabetic (T2DM) patients without heart failure (HF).

METHODS

This study was a retrospective single-center observational study that enrolled 10 T2DM/non-HF outpatients for whom the SGLT2i empagliflozin (daily oral dose of 10 mg) was prescribed. Among these 10 patients, 6 underwent detailed clinical testing that included hormonal and metabolic blood tests.

RESULTS

Empagliflozin treatment for 1-2 months decreased body weight (- 2.69 ± 1.9 kg; p = 0.002) and HbA1c (- 0.88 ± 0.55%; p = 0.0007). The hemoglobin (+ 0.27 ± 0.36 g/dL; p = 0.04) and hematocrit (+ 1.34 ± 1.38%; p = 0.014) values increased, but the serum creatinine concentration remained unchanged. The serum chloride concentration increased from 104 ± 3.23 to 106 ± 2.80 mEq/L (p = 0.004), but the sodium and potassium concentrations did not change. The spot urinary sodium concentration decreased from 159 ± 43 to 98 ± 35 mEq/L (p < 0.02) and the spot urinary chloride tended to decrease (from 162 ± 59 to 104 ± 36 mEq/L, p < 0.08). Both renin and aldosterone tended to be activated (5/6, 83%). The strong organic acid metabolite concentrations of serum acetoacetate (from 42 ± 25 to 100 ± 45 μmol/L, p < 0.02) and total ketone bodies (from 112 ± 64 to 300 ± 177 μmol/L, p < 0.04) increased, but the actual HCO3 - concentration decreased (from 27 ± 2.5 to 24 ± 1.6 mEq/L, p < 0.008).

CONCLUSIONS

The present study demonstrated that SGLT2i enhances the serum chloride concentration in T2DM patients and suggests that the effect is mediated by the possible following mechanisms: (1) enhanced reabsorption of urinary chloride by aldosterone activation due to blood pressure lowering and blood vessel contraction effects, (2) reciprocal increase in the serum chloride concentration by reducing the serum HCO3 - concentration via a buffering effect of strong organic acid metabolites, and (3) reduced NaHCO3 reabsorption and concurrently enhanced chloride reabsorption in the urinary tubules by inhibiting Na+-H+ exchanger 3 in the renal proximal tubules. Thus, the diuretic SGLT2i induces excessive extravascular fluid to drain into the vascular space by the enhanced vascular "tonicity" caused by the elevated serum chloride concentration.

Euglycemic ketoacidosis induced by therapeutic fasting in a non-diabetic patient

BACKGROUND

Ketoacidosis is a severe metabolic complication mainly reported in diabetic patients. Therapeutic fasting is a millennial worldwide practice, believed to improve a large panel of health conditions, but its efficiency and safety profile have not yet been established. We report here a case of euglycemic ketoacidosis in a non-diabetic woman.

CASE DESCRIPTION

A 51-year-old woman without a history of excessive alcohol use or medical history, except for a depressive disorder, was admitted in the emergency room for altered general status, deep asthenia, muscular weakness, articular pain, nausea, vomiting, and consciousness disorders. She was practicing during the previous 48 h a therapeutic fasting following a progressive restrictive diet for 4 d. She was diagnosed with ketoacidosis and hospitalized in the intensive care unit. Her laboratory test results indicated pH 7.28, bicarbonate 7 mmol/L, significant ketone bodies, glycemia 8.9 mmol/L without glycosuria, and negative blood alcohol assessment. Glycated hemoglobin was 5.5%, and blood glucose never went above 9 mmol/L. Serum concentrations of free fatty acids were high at 1.13 mmol/L (normal range: 0.13-0.45). Plasma insulin and peptide C were in the normal ranges. Comprehensive plasma and urinary biochemistry panels, including energetic substrates, and chromatography of amino acids and organic acids did not indicate any energetic or metabolic deficiency. The ketoacidosis regressed, and the overall outcome was favorable after intravenous glucose infusion for 48 h, without insulin requirement.

CONCLUSIONS

This report is the first case, to our knowledge, of euglycemic ketoacidosis thought to be induced by therapeutic fasting in a non-diabetic patient. Practitioners should be aware of this complication of fasting.

Correlation between the pKa and nuclear shielding of α-hydrogen of ketones

The α-H acidity is an important chemical property of ketones that has attracted much research interest. Theoretical prediction of pK_a for ketone α-H is significant. In this work, we theoretically studied the nuclear shielding of various α-Hs in a set of ketones and that of the corresponding enolic hydroxyl Hs in tautomeric enol forms. It has been demonstrated through linear regression analyses that the pK_a values of these ketones correlate with both sets of the calculated nuclear shielding values. The correlation coefficient R² of the linear correlation relationship is 0.90. The present work has provided a new approach to computationally evaluating the acidity of α-Hs in ketones, enabling us to semi-empirically predict the ketone α-H acidity from the calculated nuclear shielding values. Graphical AbstractExperimental pK_a values in DMSO vs predicted pK_a values calculated from ¹H nuclear shielding for the hydroxyl hydrogens in the enol forms and for the α-Hs in the keto forms. The surrounding solvent effects were modelled by keto/enol-DMSO clusters and SMD solvent models.

Cu(OTf)2-catalyzed Beckmann Rearrangement of Ketones Using Hydroxylamine-O-sulfonic Acid (HOSA)

The Beckmann Rearrangement (BKR) of ketones to secondary amides often requires harsh reaction conditions that limit its practicality and scope. Herein, we describe the Cu(OTf)2-catalyzed BKR of ketones under mild reaction conditions using hydroxylamine-O-sulfonic acid (HOSA), a commercial water soluble aminating agent. This method is compatible with most functional groups and directly provides the desired amides in good to excellent yields.

Inhibitory Effects of Tofogliflozin on Cardiac Hypertrophy in Dahl Salt-Sensitive and Salt-Resistant Rats Fed a High-Fat Diet

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are drugs for diabetes and might prevent heart failure. In this study, we investigated the effects of tofogliflozin, an SGLT2 inhibitor, on cardiac hypertrophy and metabolism in hypertensive rats fed a high-fat diet. Dahl salt-sensitive (DS) rats, hypertensive model rats, and Dahl salt-resistant (DR) rats, non-hypertensive model rats, were fed a high-salt and high-fat diet containing tofogliflozin (0.005%) for 9 weeks to examine the effects of this drug on cardiac hypertrophy and metabolism. Tofogliflozin tended to suppress a rise of the systolic blood pressure, relative to the control, throughout the treatment period in both DR and DS rats, and significantly suppress a rise of the systolic blood pressure, relative to the control, at the 9th week in DS rats. Tofogliflozin reduced cardiac hypertrophy (heart weight/body weight) not only in DS rats but also in DR rats. Histological analysis showed that tofogliflozin significantly decreased cardiomyocyte hypertrophy and perivascular fibrosis in both DS and DR rats. Tofogliflozin significantly decreased the expression levels of genes related to cardiac hypertrophy (encoding for natriuretic peptides A and B and interleukin-6), and to cardiac fibrosis (encoding for transforming growth factor-β1 and collagen type IV), in DS rats. Recent studies have shown that hypertrophied and failing hearts shift to oxidizing ketone bodies as a significant fuel source. We also performed metabolome analysis for ventricular myocardial tissue. Tofogliflozin reduced 3-hydroxybutyrate, a ketone body, and significantly decreased the expression levels of β-hydroxybutyrate dehydrogenase 1 and 3-oxoacid CoA-transferase, which are related to ketone oxidization. In conclusion, tofogliflozin ameliorated cardiac hypertrophy and fibrosis along with reduction of ketone usage in myocardial tissue.

Exogenous Ketone Bodies as Promising Neuroprotective Agents for Developmental Brain Injury

Ketone bodies are a promising area of neuroprotection research that may be ideally suited to the injured newborn. During normal development, the human infant is in significant ketosis for at least the first week of life. Ketone uptake and metabolism is upregulated in the both the fetus and neonate, with ketone bodies providing at least 10% of cerebral metabolic energy requirements, as well as being the preferred precursors for the synthesis of fatty acids and cholesterol. At the same time, ketone bodies have been shown to have multiple neuroprotective effects, including being anticonvulsant, decreasing oxidative stress and inflammation, and epigenetically upregulating the production of neurotrophic factors. While ketogenic diets and exogenous ketosis are largely being investigated in the setting of adult brain injury, the adaptation of the neonate to ketosis suggests that developmental brain injury may be the area most suited to the use of ketones for neuroprotection. Here, we describe the mechanisms by which ketone bodies exert their neuroprotective effects, and how these may translate to benefits within each of the phases of neonatal asphyxial brain injury.

Spontaneous ketonuria and risk of incident diabetes: a 12 year prospective study

AIMS/HYPOTHESIS

Ketones may be regarded as a thrifty fuel for peripheral tissues, but their clinical prognostic significance remains unclear. We investigated the association between spontaneous fasting ketonuria and incident diabetes in conjunction with changes in metabolic variables in a large population-based observational study.

METHODS

We analysed 8703 individuals free of diabetes at baseline enrolled in the Korean Genome and Epidemiology Study, a community-based 12 year prospective study. Individuals with (n = 195) or without fasting ketonuria were matched 1:4 by propensity score. Incident diabetes was defined as fasting plasma glucose ≥7.0 mmol/l, post-load 2 h glucose ≥11.1 mmol/l on biennial OGTTs, or current use of glucose-lowering medication. Using Cox regression models, HRs for developing diabetes associated with the presence of ketonuria at baseline were analysed.

RESULTS

Over 12 years, of the 925 participants in the propensity score-matched cohort, 190 (20.5%) developed diabetes. The incidence rate of diabetes was significantly lower in participants with spontaneous ketonuria compared with those without ketonuria (HR 0.63; 95% CI 0.41, 0.97). Results were virtually identical when participants with fasting ketonuria were compared against all participants without ketonuria (after multivariate adjustment, HR 0.66; 95% CI 0.45, 0.96). During follow-up, participants with baseline ketonuria maintained lower post-load 1 h and 2 h glucose levels and a higher insulinogenic index despite comparable baseline values.

CONCLUSIONS/INTERPRETATION

The presence of spontaneous fasting ketonuria was significantly associated with a reduced risk of diabetes, independently of metabolic variables. Our findings suggest that spontaneous fasting ketonuria may have a potential preventive role in the development of diabetes.

A ketogenic diet diminishes behavioral responses to cocaine in young adult male and female rats

Ketogenic diets (KDs) are high fat, low carbohydrate formulations traditionally used to treat epilepsy; more recently, KDs have shown promise for a wide range of other neurological disorders. Drug addiction studies suggest that repeated exposure to drugs of abuse, including cocaine, results in a suite of neurobiological changes that includes neuroinflammation, decreased glucose metabolism, and disordered neurotransmission. Given that KDs positively regulate these factors, we addressed whether administration of a KD has potential as a novel therapy for drug addiction. In this study, male and female Sprague-Dawley rats were placed on a KD or a control diet (CD), beginning at five weeks of age and continuing through the end of behavioral testing. Three weeks after initiation of dietary treatments, rats received daily i.p. injections of cocaine (15 mg/kg) or saline vehicle for one week, were drug free for a subsequent week, and then all animals received a final challenge injection of 15 mg/kg cocaine. In the absence of cocaine injections, stereotyped locomotor responses were minimal and were unaffected by dietary treatment. In contrast, both males and females fed a KD exhibited decreased cocaine-induced stereotyped responses as compared to CD-fed rats. The sensitization of ambulatory responses was also disrupted in KD-fed rats. These results suggest that KDs directly impact dopamine-mediated behaviors, and hence may hold potential as a therapy for drug addiction.

Enantioselective anti-Mannich reaction catalyzed by modularly designed organocatalysts

A highly stereoselective method for achieving the anti-Mannich reaction of aldehydes and ketones with ethyl (4-methoxyphenylimino)acetate was realized using the modularly designed organocatalysts (MDOs) self-assembled from cinchona alkaloid derivatives and (A)-pyrrolidien-3-carboxylic acid in the reaction media. The desired anti-Mannich products were obtained in good to excellent yields (up to 93%), excellent diastereoselectivities (up to 99:1 dr), and good to high enantioselectivities (up to 99% ee).

Volatile compounds and odour characteristics of seven species of dehydrated edible seaweeds

The volatile fraction of dehydrated edible seaweeds belonging to seven species (Himanthalia elongata, Laminaria ochroleuca, Palmaria palmata, Porphyra umbilicalis, Saccharina latissima, Ulva lactuca and Undaria pinnatifida) was analyzed by gas chromatography-mass spectrometry, after solid-phase microextraction of samples. Thirty-six hydrocarbons, 34 ketones, 28 aldehydes, 23 alcohols, 8 carboxylic acids, 6 halogenated compounds, 4 furans, 3 esters, 2 sulphur compounds, 2 pyrazines, 1 pyridine and 1 amine were detected among the 151 volatile compounds found in seaweeds. There were significant differences between seaweed species for all the volatile compounds. Hydrocarbons reached their highest levels in U. pinnatifida, ketones in P. umbilicalis, aldehydes in P. palmata and P. umbilicalis, alcohols in P. umbilicalis, carboxylic acids in S. latissima, and halogenated compounds in L. ochroleuca and S. latissima. Sensory analysis revealed that P. palmata, U. lactuca and H. elongata were the seaweeds showing the most potent seafood odour and seaweed odour characteristics.

The Male Produced Aggregation Pheromone of a Strawberry Sap Beetle, Lobiopa insularis (Coleoptera: Nitidulidae)

The nitidulid beetle Lobiopa insularis is an important pest of strawberry crops in the United States and Brazil. Both larvae and adults feed on ripe strawberries, causing 20-70% loss in production during serious infestations. Aiming at the development of efficient, clean, and highly specific pest management systems, semiochemicals, especially pheromones, are particularly useful. Analyses of the extracts of both males and females obtained from aeration of live beetles showed the presence of three male specific compounds, 2-nonanone, 2-undecanone, and 2-undecanol (in an enantiomeric ratio of S:R = 3.5:1). This is the first record of ketones and an alcohol as pheromone components in Nitidulidae. These compounds were emitted by males in amounts of 0.3:6:1.5 ng per insect within 24 h (1:30:3), respectively, during the scotophase, indicating nocturnal sexual activity. Field tests with pitfall traps containing different mixtures of compounds and ripe strawberries as a co-attractant summed up to five treatments with 25 replications. As a result, 59% males and 41% females (1:0.7) were caught, indicating the L. insularis pheromone to cause aggregation of both sexes. Results of the field tests showed that the attractivity of the binary mixture of ketones (T3) differed from the control (T5), from traps with 2-undecanone alone (T4), and from the mixture of 2-undecanone and racemic 2-undecanol (T2). Moreover, the activity of the ternary mixture of compounds (T1) was not different from that of T3, indicating that the racemic alcohol did not positively influence trap catches. In future applications, a mixture of synthetic strawberry-derived compounds that are attractive to L. insularis may substitute rapidly decaying fruit in the field, maintaining catches for longer periods. Because of its efficiency and low cost, a mixture of 2-undecanone and 2-nonanone is recommended to catch adult L. insularis in the field.

The relationship between d-beta-hydroxybutyrate blood concentrations and seizure control in children treated with the ketogenic diet for medically intractable epilepsy

Objective

The ketogenic diet (KD) is a proven treatment for drug‐resistant (DR) seizures in children and adolescents. However, the relationship between seizure control and the most commonly measured metabolite of the diet, the ketone body d‐beta‐hydroxybutyrate (D‐BHB), is controversial. This study was performed to clarify the relationship because specific ketone bodies may be useful as biomarkers of diet efficacy.

Methods

Families of children with DR seizures were approached for participation in this open‐label, prospective study when they were referred for the KD at two western Canadian children's hospitals. Inclusion criteria included documentation of DR seizures without exclusion based on age, sex, seizure, or syndrome type. Patients were excluded if they were referred for treatment of a metabolic disorder independent of seizures. Seizures were quantified via parental report and standardized as seizure frequency per 28 days. Epilepsy syndromes were identified on the basis of the medical record. Blood D‐BHB was determined by tandem mass spectrometry.

Results

A total of 23 patients were recruited from both sites. Data from five individuals were excluded because these seizures occurred in clusters, leaving 18 patients for the primary analysis. In the latter group, a clear positive correlation was present between measures of seizure frequency and D‐BHB concentrations. However, this failed to reach statistical significance, likely because of the relatively small numbers.

Significance

A trend clearly exists between seizure frequency and D‐BHB levels, so we should not be dissuaded by the lack of statistical significance because it possibly results from methodological techniques, especially sample size. These results call for a larger prospective study in which seizure frequency is assessed at the point of care in a standardized fashion so as to determine whether D‐BHB can be used as a reliable biomarker of KD efficacy.

Detection of Ketones by a Novel Technology: Dipolar Proton Transfer Reaction Mass Spectrometry (DP-PTR-MS)

Proton transfer reaction mass spectrometry (PTR-MS) has played an important role in the field of real-time monitoring of trace volatile organic compounds (VOCs) due to its advantages such as low limit of detection (LOD) and fast time response. Recently, a new technology of proton extraction reaction mass spectrometry (PER-MS) with negative ions OH^- as the reagent ions has also been presented, which can be applied to the detection of VOCs and even inorganic compounds. In this work, we combined the functions of PTR-MS and PER-MS in one instrument, thereby developing a novel technology called dipolar proton transfer reaction mass spectrometry (DP-PTR-MS). The selection of PTR-MS mode and PER-MS mode was achieved in DP-PTR-MS using only water vapor in the ion source and switching the polarity. In this experiment, ketones (denoted by M) were selected as analytes. The ketone (molecular weight denoted by m) was ionized as protonated ketone [M + H]⁺ [mass-to-charge ratio (m/z) m + 1] in PTR-MS mode and deprotonated ketone [M - H]^- (m/z m - 1) in PER-MS mode. By comparing the m/z value of the product ions in the two modes, the molecular weight of the ketone can be positively identified as m. Results showed that whether it is a single ketone sample or a mixed sample of eight kinds of ketones, the molecular weights can be detected with DP-PTR-MS. The newly developed DP-PTR-MS not only maintains the original advantages of PTR-MS and PER-MS in sensitive and rapid detection of ketones, but also can estimate molecular weight of ketones. Graphical Abstract ᅟ.