BST1 regulates nicotinamide riboside metabolism via its glycohydrolase and base-exchange activities.

Nicotinamide riboside (NR) is one of the orally bioavailable NAD+ precursors and has been demonstrated to exhibit beneficial effects against aging and aging-associated diseases. However, the metabolic pathway of NR in vivo is not yet fully understood. Here, we demonstrate that orally administered NR increases NAD+ level via two different pathways. In the early phase, NR was directly absorbed and contributed to NAD+ generation through the NR salvage pathway, while in the late phase, NR was hydrolyzed to nicotinamide (NAM) by bone marrow stromal cell antigen 1 (BST1), and was further metabolized by the gut microbiota to nicotinic acid, contributing to generate NAD+ through the Preiss-Handler pathway. Furthermore, we report BST1 has a base-exchange activity against both NR and nicotinic acid riboside (NAR) to generate NAR and NR, respectively, connecting amidated and deamidated pathways. Thus, we conclude that BST1 plays a dual role as glycohydrolase and base-exchange enzyme during oral NR supplementation.

NAD+ supplementation reduces neuroinflammation and cell senescence in a transgenic mouse model of Alzheimer's disease via cGAS-STING.

Alzheimer's disease (AD) is a progressive and fatal neurodegenerative disorder. Impaired neuronal bioenergetics and neuroinflammation are thought to play key roles in the progression of AD, but their interplay is not clear. Nicotinamide adenine dinucleotide (NAD+) is an important metabolite in all human cells in which it is pivotal for multiple processes including DNA repair and mitophagy, both of which are impaired in AD neurons. Here, we report that levels of NAD+ are reduced and markers of inflammation increased in the brains of APP/PS1 mutant transgenic mice with beta-amyloid pathology. Treatment of APP/PS1 mutant mice with the NAD+ precursor nicotinamide riboside (NR) for 5 mo increased brain NAD+ levels, reduced expression of proinflammatory cytokines, and decreased activation of microglia and astrocytes. NR treatment also reduced NLRP3 inflammasome expression, DNA damage, apoptosis, and cellular senescence in the AD mouse brains. Activation of cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING) are associated with DNA damage and senescence. cGAS-STING elevation was observed in the AD mice and normalized by NR treatment. Cell culture experiments using microglia suggested that the beneficial effects of NR are, in part, through a cGAS-STING-dependent pathway. Levels of ectopic (cytoplasmic) DNA were increased in APP/PS1 mutant mice and human AD fibroblasts and down-regulated by NR. NR treatment induced mitophagy and improved cognitive and synaptic functions in APP/PS1 mutant mice. Our findings suggest a role for NAD+ depletion-mediated activation of cGAS-STING in neuroinflammation and cellular senescence in AD.

NAD+ supplementation prevents STING-induced senescence in ataxia telangiectasia by improving mitophagy.

Senescence phenotypes and mitochondrial dysfunction are implicated in aging and in premature aging diseases, including ataxia telangiectasia (A-T). Loss of mitochondrial function can drive age-related decline in the brain, but little is known about whether improving mitochondrial homeostasis alleviates senescence phenotypes. We demonstrate here that mitochondrial dysfunction and cellular senescence with a senescence-associated secretory phenotype (SASP) occur in A-T patient fibroblasts, and in ATM-deficient cells and mice. Senescence is mediated by stimulator of interferon genes (STING) and involves ectopic cytoplasmic DNA. We further show that boosting intracellular NAD+ levels with nicotinamide riboside (NR) prevents senescence and SASP by promoting mitophagy in a PINK1-dependent manner. NR treatment also prevents neurodegeneration, suppresses senescence and neuroinflammation, and improves motor function in Atm-/- mice. Our findings suggest a central role for mitochondrial dysfunction-induced senescence in A-T pathogenesis, and that enhancing mitophagy as a potential therapeutic intervention.

Oral delivery of carrier-free dual-drug nanocrystal self-assembled microspheres improved NAD+ bioavailability and attenuated cardiac ischemia/reperfusion injury in mice.

Nicotinamide riboside (NR), as a dietary supplement, can be converted to nicotinamide adenine dinucleotide (NAD+) in cells to support mitochondrial energy metabolism. However, the efficacy of oral administrated NR is limited due to its quick degradation in circulation and low bioavailability in targeted organs. In this study, we fabricated nanocrystal self-assembled microspheres by Nano Spray Dryer for oral delivery of NR. The structure of NR and resveratrol (RES) nanocrystal self-assembled microspheres (NR/RESms) is confirmed by the morphology, chemical structure, and crystallization. The NR/RESms displayed restricted NR release at the gastric acid-mimic condition (<15% in the first 8 hours), while achieved accelerated NR release in an enteric-mimic environment (>46% within 8 hours). Oral administration of NR/RESms for 8 hours significantly elevated NAD+ levels in serum (169.88 nM versus 30.93 nM in the NR group, p < .01; and 66.89 nM in the NR + RES group, p < .05), and enhanced NAD+ abundance in multiple organs in mice, exhibiting an improved oral NAD+ bioavailability. In addition, without any serious adverse effects on major organs, oral delivery of NR/RESms attenuated myocardial infarction (15.82% versus 19.38% in the I/R + NR group and 20.76% in the I/R + NR + RES group) in a cardiac ischemia/reperfusion (I/R) injury mouse model. Therefore, our data supported that the NR/RESms is a promising candidate as NAD+ booster for oral administration.

Can nicotinamide riboside protect against cognitive impairment?

PURPOSE OF REVIEW: The present review aims to address the clinical benefits of using nicotinamide riboside, a precursor to the essential pyridine nucleotide, nicotinamide adenine dinucleotide (NAD+) as a therapeutic agent to attenuate age-related cognitive decline. RECENT FINDINGS: Oral supplementation with nicotinamide riboside can inhibit the accumulation of pathological hallmarks of Alzheimer's disease and improve learning and memory in various murine models for dementia. Nicotinamide riboside can also reduce DNA damage, neuroinflammation, apoptosis, and improved hippocampal synaptic plasticity in diabetic mice, and another Alzheimer's disease mouse model. The cognitive benefits of nicotinamide riboside in Alzheimer's disease models may be modulated in part by upregulation of proliferator-activated-γ coactivator 1α-mediated ß-secretase 1(BACE-1) ubiquitination and degradation, preventing Aß production in the brain. Nicotinamide riboside also maintained blood-brain barrier integrity and maintained the gut microbiota in a mouse model for cerebral small vessel disease and alcohol-induced depression, respectively. Oral nicotinamide riboside has been shown to be bioavailable and well tolerated in humans with limited adverse effects compared to other NAD+ precursors. SUMMARY: Oral nicotinamide riboside may represent a promising stratagem to improve cognitive decline during 'normal' ageing, Alzheimer's disease and other diseases. Results from recent clinical trials are needed to enumerate the preclinical benefits in humans.

Magnetic resonance spectroscopy for detection of choline kinase inhibition in the treatment of brain tumors.

Abnormal choline metabolism is a hallmark of cancer and is associated with oncogenesis and tumor progression. Increased choline is consistently observed in both preclinical tumor models and in human brain tumors by proton magnetic resonance spectroscopy (MRS). Thus, inhibition of choline metabolism using specific choline kinase inhibitors such as MN58b may be a promising new strategy for treatment of brain tumors. We demonstrate the efficacy of MN58b in suppressing phosphocholine production in three brain tumor cell lines. In vivo MRS studies of rats with intracranial F98-derived brain tumors showed a significant decrease in tumor total choline concentration after treatment with MN58b. High-resolution MRS of tissue extracts confirmed that this decrease was due to a significant reduction in phosphocholine. Concomitantly, a significant increase in poly-unsaturated lipid resonances was also observed in treated tumors, indicating apoptotic cell death. MRI-based volume measurements demonstrated a significant growth arrest in the MN58b-treated tumors in comparison with saline-treated controls. Histologically, MN58b-treated tumors showed decreased cell density, as well as increased apoptotic cells. These results suggest that inhibition of choline kinase can be used as an adjuvant to chemotherapy in the treatment of brain tumors and that decreases in total choline observed by MRS can be used as an effective pharmacodynamic biomarker of treatment response.

Cardiometabolic effects of two coffee blends differing in content for major constituents in overweight adults: a randomized controlled trial.

PURPOSE: The hypothesis was tested that coffee types differing in content of major constituents also differ with regard to cardiometabolic effects. METHODS: Overweight persons (n = 118) were randomized to consume a dark roast [rich in N-methylpyridinium (NMP)] or medium roast (rich in caffeoylquinic acids, trigonelline) coffee blend for 3 months, after a washout period of 4 weeks. Before and after the intervention period, body weight and 15 further general and biochemical parameters were determined. RESULTS: Participants consumed an average of 4-5 cups per day. Mean body weight, body mass index and waist circumference did not change during the coffee consumption phase in either of the study groups. Systolic blood pressure decreased in the dark roast coffee group only (p < 0.05). High-density lipoprotein cholesterol levels increased in the medium roast coffee group only, and triglyceride levels increased in the dark roast coffee group only. Glucoregulation and insulin levels were not affected, although there was a small increase of hemoglobin A1c values in both groups. An increase of adiponectin levels occurred in the medium roast coffee group only and was negatively associated with NMP concentrations. Differences did not remain statistically significant after correction for multiple testing. CONCLUSIONS: Medium and dark roast coffee blends exert small but possibly relevant different cardiometabolic effects. Further studies of health outcomes in relation to coffee constituents seem warranted.

Consumption of a dark roast coffee decreases the level of spontaneous DNA strand breaks: a randomized controlled trial.

PURPOSE: Coffee consumption has been reported to decrease oxidative damage in peripheral white blood cells (WBC). However, effects on the level of spontaneous DNA strand breaks, a well established marker of health risk, have not been specifically reported yet. We analyzed the impact of consuming a dark roast coffee blend on the level of spontaneous DNA strand breaks. METHODS: Healthy men (n = 84) were randomized to consume daily for 4 weeks either 750 ml of fresh coffee brew or 750 ml of water, subsequent to a run in washout phase of 4 weeks. The study coffee was a blend providing high amounts of both caffeoylquinic acids (10.18 ± 0.33 mg/g) and the roast product N-methylpyridinium (1.10 ± 0.05 mg/g). Before and after the coffee/water consumption phase, spontaneous strand breaks were determined by comet assay. RESULTS: At baseline, both groups exhibited a similar level of spontaneous DNA strand breaks. In the intervention phase, spontaneous DNA strand breaks slightly increased in the control (water only) group whereas they significantly decreased in the coffee group, leading to a 27% difference within both arms (p = 0.0002). Food frequency questionnaires indicated no differences in the overall diet between groups, and mean body weight during the intervention phases remained stable. The consumption of the study coffee substantially lowered the level of spontaneous DNA strand breaks in WBC. CONCLUSION: We conclude that regular coffee consumption contributes to DNA integrity.

Antithrombotic effects of pyridinium compounds formed from trigonelline upon coffee roasting.

Coffee may exert a preventive effect on arterial thrombosis. Trigonelline is one of the most abundant compounds in coffee that undergoes pyrolysis upon roasting of coffee beans. The aim of the present study was to identify pyridinium compounds formed upon trigonelline pyrolysis and coffee roasting and to investigate the effect of three of them, i.e., 1-methylpyridine and 1,3- and 1,4-dimethylpyridine, on experimentally induced arterial thrombosis in rats. 1,3- and 1,4-dimethylpyridine but not 1-methylpyridine inhibited arterial thrombus formation. 1,3-Dimethylpyridine inhibited platelet aggregation and reduced fibrin formation in platelet-rich plasma, whereas 1,4-dimethylpyridine increased the plasma level of 6-keto-PGF1α. 1,4-Dimethylpyridine slightly increased rat tissue plasminogen activator plasma activity. In summary, we demonstrated that pyridinium compounds display mild antithrombotic properties due to stimulation by prostacyclin release (1,4-dimethylpyridine) and inhibition of platelet aggregation (1,3-dimethylpyridine). Those pyridinium compounds may, to some extent, be responsible for the beneficial effects of coffee drinking.

A dark brown roast coffee blend is less effective at stimulating gastric acid secretion in healthy volunteers compared to a medium roast market blend.

Coffee consumption sometimes is associated with symptoms of stomach discomfort. This work aimed to elucidate whether two coffee beverages, containing similar amounts of caffeine, but differing in their concentrations of (ß) N-alkanoyl-5-hydroxytryptamides (C5HTs), chlorogenic acids (CGAs), trigonelline, and N-methylpyridinium (N-MP) have different effects on gastric acid secretion in healthy volunteers. The intragastric pH after administration of bicarbonate with/without 200 mL of a coffee beverage prepared from a market blend or dark roast blend was analyzed in nine healthy volunteers. Coffee beverages were analyzed for their contents of C5HT, N-MP, trigonelline, CGAs, and caffeine using HPLC-DAD and HPLC-MS/MS. Chemical analysis revealed higher concentrations of N-MP for the dark brown blend (87 mg/L) compared to the market blend coffee (29 mg/L), whereas concentrations of C5HT (0.012 versus 0.343 mg/L), CGAs (323 versus 1126 mg/L), and trigonelline (119 versus 343 mg/L) were lower, and caffeine concentrations were similar (607 versus 674 mg/mL). Gastric acid secretion was less effectively stimulated after administration of the dark roast blend coffee compared to the market blend. Future studies are warranted to verify whether a high ratio of N-MP to C5HT and CGAs is beneficial for reducing coffee-associated gastric acid secretion.

A comparison of tabun-inhibited rat brain acetylcholinesterase reactivation by three oximes (HI-6, obidoxime, and K048) in vivo detected by biochemical and histochemical techniques.

Tabun belongs to the most toxic nerve agents. Its mechanism of action is based on acetylcholinesterase (AChE) inhibition at the peripheral and central nervous systems. Therapeutic countermeasures comprise administration of atropine with cholinesterase reactivators able to reactivate the inhibited enzyme. Reactivation of AChE is determined mostly biochemically without specification of different brain structures. Histochemical determination allows a fine search for different structures but is performed mostly without quantitative evaluation. In rats intoxicated with tabun and treated with a combination of atropine and HI-6, obidoxime, or new oxime K048, AChE activities in different brain structures were determined using biochemical and quantitative histochemical methods. Inhibition of AChE following untreated tabun intoxication was different in the various brain structures, having the highest degree in the frontal cortex and reticular formation and lowest in the basal ganglia and substantia nigra. Treatment resulted in an increase of AChE activity detected by both methods. The highest increase was observed in the frontal cortex. This reactivation was increased in the order HI-6 < K048 < obidoxime; however, this order was not uniform for all brain parts studied. A correlation between AChE activity detected by histochemical and biochemical methods was demonstrated. The results suggest that for the mechanism of action of the nerve agent tabun, reactivation in various parts of the brain is not of the same physiological importance. AChE activity in the pontomedullar area and frontal cortex seems to be the most important for the therapeutic effect of the reactivators. HI-6 was not a good reactivator for the treatment of tabun intoxication.

In vivo two-photon fluorescence microscopy opens a new area for investigation of the excretion of cationic drugs in the kidney.

Polyspecific transporters mediate excretion and reabsorption of organic cations in kidney. With in vivo two-photon fluorescence microscopy, excretion and reabsorption of a fluorescent cation in rat renal proximal tubules was resolved. In combination with specific inhibitors, the contribution of individual cation transporters can be determined.

Acute toxicity of cyclohexylmethylphosphonofluoridate (CMPF) in rhesus monkeys: serum biochemical and hematologic changes.

Changes in serum biochemical and hematological parameters were studied in 20 male rhesus monkeys following acute poisoning by the organophosphate nerve agent cyclohexylmethylphosphonofluoridate (CMPF or GF). Animals were challenged with 5 x LD50 GF (233 micrograms/kg, IM) following pretreatment with pyridostigmine (0.3-0.7 mg/kg per 24 h) and treated with atropine (0.4 mg/kg, IM) and either 2-PAM (25.7 mg/kg, IM) or H16 (37.8 mg/kg, IM) at the onset of clinical signs or at 1 min after exposure. Muscle fasciculations, tremors, or convulsions occurred in 19 of 20 animals. Serum biochemical and hematologic parameters were analyzed 2 days and 7 days after exposure and compared to pre-exposure baseline values. Significant increases in creatine kinase (CK), lactate dehydrogenase (LD), aspartate transaminase (AST), alanine transaminase (ALT) and potassium ion (K+), associated with damage to striated muscle and metabolic acidosis, occurred in both oxime-treated groups 2 days after exposure. Total protein, albumin, red blood cell (RBC) count, hemoglobin concentration (Hb) and hematocrit (Hct), were decreased in both oxime-treated groups at 7 days. The results demonstrate that animals exposed to a single high dose of GF and treated with standard therapy exhibit changes in serum biochemical and hematological indices directly and indirectly associated with their clinical presentations.

[Attempt at a mathematical definition of pachycurare dosage. Application for pancuronium and AH 8165]. / Essai de définition mathématique de la posologie d'un pachycarare. Application pour le pancuronium et l'AH 8165

Correlations among the elements indispensable to the choice of an average dose of pachycurare are established for surgical needs. Weight and duration of the surgery jointly allow to foresee with approximately 80 p. 100 accuracy the effective dose required for a surgical curarization controlled according to clinical and electromyographical criteria. After calculation of the average consumption of pachycurare per unit of time, a group of curves is established by successive integrations of additional doses representing a family of parabolae corresponding to a second-degree equation: P = alpha + beta t + gamma t2 where P: the cumulative dose for a determined period of time, per kg of body weight and thus total dose if t: the duration of the surgery, t: the time variable, alpha, beta and gamma: significant calculated coefficients. This analytical function established for the use of Pancuronium - bromide in surgery, is also being tried for the curarizing substance: AH.8165.

A clinical comparison of AH8165 and pancuronium as muscle relaxants in patients undergoing cardiac surgery.

The non-depolarizing muscle relaxant AH8165 has been compared at two doses (0.5 and 1.0 mg/kg) with pancuronium (0.1 mg/kg) during induction of anaesthesia for patients having major cardiac surgery. After barbiturate-opiate premedication and thiopentone induction, administration of pancuronium was followed by no significant alteration in heart rate or arterial pressure. Both doses of AH8165 werr followed by significant tachycardia, and the higher dose by arterial hypotension. The lower dose of AH8165 was unsatisfactory for tracheal intubation, but the AH8165 1 mg/kg gave intubating conditions similar to those with pancuronium 0.1 mg/kg.