Technology and functional insights into the nicotinamide mononucleotide for human health.

Nicotinamide mononucleotide (NMN), a naturally occurring biologically active nucleotide, mainly functions via mediating the biosynthesis of NAD+. In recent years, its excellent pharmacological activities including anti-aging, treating neurodegenerative diseases, and protecting the heart have attracted increasing attention from scholars and entrepreneurs for production of a wide range of formulations, including functional food ingredients, health care products, active pharmaceuticals, and pharmaceutical intermediates. Presently, the synthesis methods of NMN mainly include two categories: chemical synthesis and biosynthesis. With the development of biocatalyst engineering and synthetic biology strategies, bio-preparation has proven to be efficient, economical, and sustainable methods. This review summarizes the chemical synthesis and biosynthetic pathways of NMN and provides an in-depth investigation on the mining and modification of enzyme resources during NMN biosynthesis, as well as the screening of hosts and optimization of chassis cells via metabolic engineering, which provide effective strategies for efficient production of NMN. In addition, an overview of the significant physiological functions and activities of NMN is elaborated. Finally, future research on technical approaches to further enhance NMN synthesis and strengthen clinical studies of NMN are prospected, which would lay the foundation for further promoting the application of NMN in nutrition, healthy food, and medicine in the future. KEY POINTS: • NMN supplementation effectively increases the level of NAD+. • The chemical and biological synthesis of NMN are comprehensively reviewed. • The impact of NMN on the treatment of various diseases is summarized.

Protein engineering of NADH pyrophosphatase for efficient biocatalytic production of reduced nicotinamide mononucleotide.

Introduction: NADH pyrophosphatase, a hydrolase catalyzing the phosphate bond of NADH to reduced nicotinamide mononucleotide, has potential applications in the food, cosmetic and pharmaceutical industry. Methods: Here, we investigated the effects of vector screening, promoter and RBS strategies on NADH pyrophosphatase expression and protein engineering on its enzymatic activity and thermal stability. Results: In this study, we describe a NADH pyrophosphatase derived from Escherichia coli (EcNudc). Strategies focusing on expression regulation including screening vectors, optimizing promoters and ribosome binding sites were utilized to enhance the productivity of EcNudc (1.8 U/mL). Moreover, protein engineering was adopted to further improve the catalytic properties of EcNudc, achieving 3.3-fold higher activity and 3.6-fold greater thermostability at 50°C. Furthermore, fermentation for the combined mutant R148A-H149E (EcNudc-M) production in a 7 L fermenter was implemented and the enzyme activity of EcNudc-M reached 33.0 U/mL. Finally, the EcNudc-M was applied in the catalysis of NADH with the highest NMNH yield of 16.65 g/L. Discussion: In conclusion, we constructed a commercially available genetically engineered strain with high activity and thermal stability of NADH pyrophosphatase, laying a broad foundation for the biocatalytic industrial production of NMNH and expand its application range.

Preoperative imaging characteristics predict poor survival and inadequate resection for left-sided pancreatic adenocarcinoma: a multi-institutional analysis.

BACKGROUND: Optimal treatment of pancreatic ductal adenocarcinoma of the neck, body and tail (PDAC-NBT) necessitates R0 surgical resection. Preoperative radiographic identification of patients likely to achieve successful oncologic resection remains difficult. This study seeks to identify preoperative imaging characteristics predictive of non-R0 resections or impaired survival for PDAC-NBT. METHODS: Patients at five high-volume centers who underwent resection for PDAC-NBT were retrospectively analyzed. The most immediate preoperative cross-sectional scan was assessed along with outcome measures of overall survival and margin status. RESULTS: 330 patients were treated between 2001 and 2016. Margin status included 247 R0 (78.2%), 67 R1 (21.2%), and 2 R2 (0.6%). A non-R0 resection predicted worse survival (p = 0.0002). On preoperative imaging, patients with tumors greater than 20 mm, tumor attenuation greater than 70 Hounsfield units, or who demonstrated pancreatic atrophy and/or calcifications also had worse survival (p = 0.010, p = 0.036, p = 0.025 respectively). Patients with tumors interfacing with the splenic artery or vein or extending posteriorly achieved fewer R0 resections (p = 0.0006, p = 0.0004, p = 0.001, respectively). CONCLUSION: Preoperative cross-sectional imaging can identify tumor characteristics associated with poor survival and non-R0 resection. Further investigation is needed to identify the appropriate surgical and treatment modifications necessary to clinically benefit this subset of patients.

Elevated plasma dihydroorotate in Miller syndrome: Biochemical, diagnostic and clinical implications, and treatment with uridine.

BACKGROUND: Miller syndrome (post-axial acrofacial dysostosis) arises from gene mutations for the mitochondrial enzyme dihydroorotate dehydrogenase (DHODH). Nonetheless, despite demonstrated loss of enzyme activity dihydroorotate (DHO) has not been shown to accumulate, but paradoxically urine orotate has been reported to be raised, confusing the metabolic diagnosis. METHODS: We analysed plasma and urine from a 4-year-old male Miller syndrome patient. DHODH mutations were determined by PCR and Sanger sequencing. Analysis of DHO and orotic acid (OA) in urine, plasma and blood-spot cards was performed using liquid chromatography-tandem mass spectrometry. In vitro stability of DHO in distilled water and control urine was assessed for up to 60h. The patient received a 3-month trial of oral uridine for behavioural problems. RESULTS: The patient had early liver complications that are atypical of Miller syndrome. DHODH genotyping demonstrated compound-heterozygosity for frameshift and missense mutations. DHO was grossly raised in urine and plasma, and was detectable in dried spots of blood and plasma. OA was raised in urine but undetectable in plasma. DHO did not spontaneously degrade to OA. Uridine therapy did not appear to resolve behavioural problems during treatment, but it lowered plasma DHO. CONCLUSION: This case with grossly raised plasma DHO represents the first biochemical confirmation of functional DHODH deficiency. DHO was also easily detectable in dried plasma and blood spots. We concluded that DHO oxidation to OA must occur enzymatically during renal secretion. This case resolved the biochemical conundrum in previous reports of Miller syndrome patients, and opened the possibility of rapid biochemical screening.

High incidence of macrotroponin I with a high-sensitivity troponin I assay.

BACKGROUND: Cardiac troponin is the preferred biomarker of myocardial injury. High-sensitivity troponin assays allow measurement of very low levels of troponin with excellent precision. After the introduction of a high-sensitivity troponin I assay the laboratory began to receive enquiries from clinicians about clinically discordant elevated troponin I results. This led to a systematic investigation and characterisation of the cause. METHODS: Routine clinical samples were measured by the Architect High Sensitive Troponin-I (hsTnI) and the VITROS Troponin I ES assays (VitrosTnI). Results that were elevated according to the Architect but not the VITROS assay (Group 1) or results elevated by both assays but disproportionately higher on the Architect (Group 2) were re-analysed for hsTnI after re-centrifugation, multiple dilutions, incubation with heterophilic blocking reagents, polyethylene glycol (PEG) precipitation, and Protein A/G/L treatment. Sephacryl S-300 HR gel filtration chromatography (GFC) was performed on selected specimens. RESULTS: A high molecular weight complex containing immunoreactive troponin I and immunoglobulin (macrotroponin I) was identified in 5% of patients with elevated hsTnI. Patients with both macrotroponin and myocardial injury had higher and longer elevation of hsTnI compared with VitrosTnI with peaks of both macrotroponin and free troponin I-C complex on GFC. CONCLUSIONS: Circulating macrotroponin I (macroTnI) causes elevated hsTnI results with the Architect High Sensitive Troponin-I assay with the potential to be clinically misleading. The assay involved in this investigation may not be the only assay affected by macrotroponin. It is important for laboratories and clinicians to be aware of and develop processes to identify and manage specimens with elevated results due to macrotroponin.

Empathy and affect: what can empathied bodies do?

While there has been much interest in the apparent benefits of empathy in improving outcomes of medical care, there is continuing concern over the philosophical nature of empathy. We suggest that part of the difficulty in coming to terms with empathy is due to the modernist dichotomies that have structured Western medical discourse, such that doctor and patient, knower and known, cognitive and emotional, subject and object are situated in oppositional terms, with the result that such accounts cannot coherently encompass an emotional doctor, or a patient as knower, or empathy as other than a possession or a trait. This paper explores what, by contrast, a radical critique of the Cartesian world view, in the form of a Deleuzean theoretical framework, would open up in new perspectives on empathy. We extend the framework of emotional geography to ask what happens when people are affected by empathy. We suggest that doctors and patients might be more productively understood as embodied subjects that are configured in their capacities by how they are affected by singular 'events' of empathy. We sketch out how the Deleuzean framework would make sense of these contentions and identify some possible implications for medical education and practice.

A Ni(i)Fe(ii) analogue of the Ni-L state of the active site of the [NiFe] hydrogenases.

[Ni(L(1))Fe((t)BuNC)4](PF6)2 is a robust Ni(II)Fe(II) complex that undergoes a reversible one-electron reduction. Spectroscopic and theoretical studies show that [Ni(L(1))Fe((t)BuNC)4](+) is an unprecedented Ni(I)Fe(II) species that reproduces the electronic configuration of the Ni-L state of the [NiFe] hydrogenases.

Should general practitioners order troponin tests?

Cardiac troponin I and T are the preferred biomarkers for assessing myocardial injury, and the timing of troponin testing is fundamental to its clinical utility. There are arguments for and against the use of troponin testing in the community, and the stance that general practitioners should never order a troponin test can be considered an oversimplification. GPs have a generally sufficient understanding of the test for use in primary care, and have a better understanding of false-negative troponin test results than false-positive results. We suggest that hospitalisation, rather than troponin testing, should be the default option for patients with symptoms suggestive of acute coronary syndrome. A single troponin test is reasonable in primary care to exclude the possibility of acute myocardial infarction in asymptomatic low-risk patients whose symptoms resolved at least 12 hours prior. GPs should factor in the complex logistics of troponin testing in the community before ordering a troponin test: results need to be accurate and timely, and might be obtained at a time of day when it is difficult to contact the doctor or the patient.

Donor management parameters and organ yield: single center results.

BACKGROUND: Management of organ donors in the intensive care unit is an emerging subject in critical care and transplantation. This study evaluates organ yield outcomes for a large number of patients managed by the Indiana Organ Procurement Organization. MATERIALS AND METHODS: This is a retrospective review of intensive care unit records from 2008-2012. Donor demographic information and seven donor management parameters (DMP) were recorded at admission, consent, 12 h after consent, and before procurement. Three study groups were created: donors meeting 0-3, 4, or 5-7 DMP. Active donor Organ Procurement Organization management began at consent; so, data analysis focuses on the 12-h postconsent time point. Outcomes included organs transplanted per donor (OTPD) and transplantation of individual solid organs. RESULTS: Complete records for 499 patients were reviewed. Organ yield was 1415 organs of 3992 possible (35%). At 12 h, donors meeting more DMP had more OTPD: 2.2 (0-3) versus 3.0 (4) versus 3.5 (5-7) (P < 0.01). Aggregate DMP met was significantly associated with transplantation of every organ except intestine. Oxygen tension, vasopressor use, and central venous pressure were the most frequent independent predictors of organ usage. There were significantly more organs transplanted for donors meeting all three of these parameters (4.5 versus 2.7, P < 0.01). CONCLUSIONS: Initial DMP met does not appear to be a significant prognostic factor for OTPD. Aggregate DMP is associated with transplantation rates for most organs, with analysis of individual parameters suggesting that appropriate management of oxygenation, volume status, and vasopressor use could lead to more organs procured per donor.

2,3,7-Trisubstituted pyrazolo[1,5-d][1,2,4]triazines: functionally selective GABAA alpha3-subtype agonists.

Novel synthetic routes have been devised for the preparation of previously inaccessible 2,3,7-trisubstituted pyrazolo[1,5-d][1,2,4]triazines 2. These compounds are high affinity ligands for the GABA(A) benzodiazepine binding site and some analogues show functional selectivity for agonism at alpha3-containing receptors over alpha1-containing receptors with the lead compound being 32.

A pyridazine series of alpha2/alpha3 subtype selective GABA A agonists for the treatment of anxiety.

The development of a series of GABA(A) alpha2/alpha3 subtype selective pyridazine based benzodiazepine site agonists as anxiolytic agents with reduced sedative/ataxic potential is described, including the discovery of 16, a remarkably alpha3-selective compound ideal for in vivo study. These ligands are antagonists at the alpha1 subtype, with good CNS penetration and receptor occupancy, and excellent oral bioavailability.

Discovery of imidazo[1,2-b][1,2,4]triazines as GABA(A) alpha2/3 subtype selective agonists for the treatment of anxiety.

The identification of a series of imidazo[1,2-b][1,2,4]triazines with high affinity and functional selectivity for the GABA(A) alpha3-containing receptor subtype is described, leading to the identification of a clinical candidate, 11. Compound 11 shows good bioavailability and half-life in preclinical species, and it is a nonsedating anxiolytic in both rat and squirrel monkey behavioral models.

Imidazo[1,2-a]pyrimidines as functionally selective and orally bioavailable GABA(A)alpha2/alpha3 binding site agonists for the treatment of anxiety disorders.

A series of high-affinity GABA(A) agonists with good oral bioavailability in rat and dog and functional selectivity for the GABA(A)alpha2 and -alpha3 subtypes is reported. The 7-trifluoromethylimidazopyrimidine 14g and the 7-propan-2-olimidazopyrimidine 14k are anxiolytic in both conditioned and unconditioned animal models of anxiety with minimal sedation observed at full BZ binding site occupancy.