A highly sensitive LC-MS/MS method for quantitative determination of 7 vitamin D metabolites in mouse brain tissue.

Despite its critical role in neurodevelopment and brain function, vitamin D (vit-D) homeostasis, metabolism, and kinetics within the central nervous system remain largely undetermined. Thus, it is of critical importance to establish an accurate, highly sensitive, and reproducible method to quantitate vit-D in brain tissue. Here, we present a novel liquid chromatography tandem mass spectrometry (LC-MS/MS) method and for the first time, demonstrate detection of seven major vit-D metabolites in brain tissues of C57BL/6J wild-type mice, namely 1,25(OH)2D3, 3-epi-1,25(OH)2D3, 1,25(OH)2D2, 25(OH)D3, 25(OH)D2, 24,25(OH)2D3, and 24,25(OH)2D2. Chromatographic separation was achieved on a pentaflurophenyl column with 3 mM ammonium formate water/methanol [A] and 3 mM ammonium formate methanol/isopropanol [B] mobile phase components. Detection was by positive ion electrospray tandem mass spectrometry with the EVOQ elite triple quadrupole mass spectrometer with an Advance ultra-high-performance liquid chromatograph and online extraction system. Calibration standards of each metabolite prepared in brain matrices were used to validate the detection range, precision, accuracy, and recovery. Isotopically labelled analogues, 1,25(OH)2D3-d3, 25(OH)D3-c5, and 24,25(OH)2D3-d6, served as the internal standards for the closest molecular-related metabolite in all measurements. Standards between 1 fg/mL and 10 ng/mL were injected with a resulting linear range between 0.001 and 1 ng, with an LLOD and LLOQ of 1 pg/mL and 12.5 pg/mL, respectively. The intra-/inter-day precision and accuracy for measuring brain vit-D metabolites ranged between 0.12-11.53% and 0.28-9.11%, respectively. Recovery in acetonitrile ranged between 99.09 and 106.92% for all metabolites. Collectively, the sensitivity and efficiency of our method supersedes previously reported protocols used to measure vit-D and to our knowledge, the first protocol to reveal the abundance of 25(OH)D2, 1,25(OH)D2, and 24,25(OH)2D2, in brain tissue of any species. This technique may be important in supporting the future advancement of pre-clinical research into the function of vit-D in neurophysiological and neuropsychiatric disorders, and neurodegeneration.

Long-Term Daily Administration of Aprepitant for the Management of Intractable Nausea and Vomiting in Children With Life-Limiting Conditions: A Case Series.

BACKGROUND: Nausea and vomiting is a common symptom in children through their end of life journey. Aprepitant, a NK-1 antagonist, has become a potent weapon in the fight against chemo-induced nausea and vomiting. However, its use in palliative care for refractory nausea and vomiting has been limited due to limited experience or evidence of continuous use. Emerging evidence suggests that continuous use is not only safe, but also effective in patients with nausea and vomiting refractory to multiple lines of antiemetic therapy. METHODS: We conducted a single centre retrospective chart review of children receiving care from a specialist palliative care team who were given continuous daily aprepitant for nausea and vomiting and were unresponsive to at least two prior lines of antiemetic therapy. Parental reports of the impact of nausea on mobility and feeding were used as proxy efficacy markers. Duration of effect and toxicity was also evaluated. RESULTS: Ten children (eight with cancer as a primary diagnosis and two with noncancer diagnoses) received continuous aprepitant and all showed resolution of nausea and vomiting and an increased ability to mobilize and tolerate feeds. No adverse events noted. CONCLUSION: Our review suggests a role for aprepitant in management of refractory nausea and vomiting, demonstrating safety and efficacy. This case series is the first report of aprepitant use in this manner in the paediatric palliative care setting.

Chronic high fat feeding paradoxically attenuates cerebral capillary dysfunction and neurovascular inflammation in Senescence-Accelerated-Murine-Prone Strain 8 mice.

Background: A body of epidemiological, clinical and preclinical studies suggest increased risk for cerebro- and cardio-vascular disease associated with dietary ingestion of long-chain saturated fatty acids (LCSFA). In wild-type rodent models, chronic ingestion of LCSFA diets are associated with increased cerebral capillary permeability, heightened neurovascular inflammation and poorer cognitive performance. However, recent studies suggest that diets enriched in fat may paradoxically attenuate elements of the ageing phenotype via a caloric support axis.Objective: The purpose of this study was to explore the effects of dietary LCSFA on cerebral capillary integrity and neurovascular inflammation in an established model of accelerated ageing, Senescence-Accelerated-Murine-Prone Strain 8 (SAMP8) mice.Methods: From 6 weeks of age, SAMP8 mice and age-matched controls were randomised to either normal chow, or to an LCSFA-enriched diet, for either 12 or 34 weeks. An additional group of SAMP8 mice were provided the LCSFA-enriched diet for 12 weeks followed by the provision of ordinary low-fat chow for 22 weeks. Ex vivo measures of cerebrovascular integrity, neurovascular inflammation and astrocytic activation, were determined via 3-dimensional immunofluorescent confocal microscopy methodologies.Results: LCSFA-fed SAMP8 mice had markedly attenuated cerebral capillary dysfunction concomitant with reduced microglial activation. In SAMP8 mice transiently maintained on an LCSFA diet for 12 weeks, suppression of neurovascular inflammation persisted. Marked hippocampal astrogliosis was evident in LCSFA-fed mice when compared to SAMP8 mice maintained on ordinary chow.Conclusion: The findings from this study support the notion that high-fat, potentially ketogenic diets, may confer neuroprotection in SAMP8 mice through a vascular-support axis.

Genetic, environmental and biomarker considerations delineating the regulatory effects of vitamin D on central nervous system function.

Studies show that vitamin D (vit-D) (25(OH)D), the bioactive metabolite (1,25(OH)2D3) and vit-D receptors (vit-D receptor; protein disulphide isomerase, family A member 3) are expressed throughout the brain, particularly in regions pivotal to learning and memory. This has led to the paradigm that avoiding vit-D deficiency is important to preserve cognitive function. However, presently, it is not clear if the common clinical measure of serum 25(OH)D serves as a robust surrogate marker for central nervous system (CNS) homeostasis or function. Indeed, recent studies report CNS biosynthesis of endogenous 25(OH)D, the CNS expression of the CYP group of enzymes which catalyse conversion to 1,25(OH)2D3 and thereafter, deactivation. Moreover, in the periphery, there is significant ethnic/genetic heterogeneity in vit-D conversion to 1,25(OH)2D3 and there is a paucity of studies which have actually investigated vit-D kinetics across the cerebrovasculature. Compared with peripheral organs, the CNS also has differential expression of receptors that trigger cellular response to 1,25(OH)2D3 metabolites. To holistically consider the putative association of peripheral (blood) abundance of 25(OH)D on cognitive function, herein, we have reviewed population and genetic studies, pre-clinical and clinical intervention studies and moreover have considered potential confounders of vit-D analysis.

Sodium alginate capsulation increased brain delivery of probucol and suppressed neuroinflammation and neurodegeneration.

AIM: To enhance the bioavailability and brain uptake of probucol and examine whether it attenuates neuroinflammation and neurodegeneration by utilizing a sodium alginate nanoencapsulation technique. MATERIALS & METHODS: Wild-type mice were given either low-fat standard chow, high-fat (HF) diet to induce neuroinflammation and neurodegeneration, HF diet supplemented with nanocapsuled probucol at a concentration of 0.1% (w/w), HF diet supplemented with noncapsulated probucol at the same concentration of 0.1%, or HF diet supplemented with noncapsulated probucol at higher concentration (1%) for 24 weeks. RESULTS & CONCLUSION: The nanoencapsulation increased the plasma and brain concentration of probucol significantly compared with the mice that was given the same dosage of probucol without capsulation, and significantly suppressed the neuroinflammation and neurodegeneration.

The vertebrate heart: an evolutionary perspective.

Convergence is the tendency of independent species to evolve similarly when subjected to the same environmental conditions. The primitive blueprint for the circulatory system emerged around 700-600 Mya and exhibits diverse physiological adaptations across the radiations of vertebrates (Subphylum Vertebrata, Phylum Chordata). It has evolved from the early chordate circulatory system with a single layered tube in the tunicate (Subphylum Urchordata) or an amphioxus (Subphylum Cephalochordata), to a vertebrate circulatory system with a two-chambered heart made up of one atrium and one ventricle in gnathostome fish (Infraphylum Gnathostomata), to a system with a three-chambered heart made up of two atria which maybe partially divided or completely separated in amphibian tetrapods (Class Amphibia). Subsequent tetrapods, including crocodiles and alligators (Order Crocodylia, Subclass Crocodylomorpha, Class Reptilia), birds (Subclass Aves, Class Reptilia) and mammals (Class Mammalia) evolved a four-chambered heart. The structure and function of the circulatory system of each individual holds a vital role which benefits each species specifically. The special characteristics of the four-chamber mammalian heart are highlighted by the peculiar structure of the myocardial muscle.