Bioavailability of Anthocyanins: Whole Foods versus Extracts.

Anthocyanins have gained significant popularity in recent years for their diverse health benefits, yet their limited bioavailability poses a challenge. To address this concern, technologies have emerged to enhance anthocyanin concentration, often isolating these compounds from other food constituents. However, the extent to which isolated anthocyanins confer health benefits compared to their whole-food counterparts remains unclear. This review explores the current literature on anthocyanin bioavailability and metabolism in the body, with a focus on comparing bioavailability when consumed as extracts versus whole foods rich in anthocyanins, drawing from in vitro, in vivo, and human clinical studies. While direct comparisons between anthocyanin bioavailability in whole foods versus isolates are scarce, prevailing evidence favours whole-food consumption over anthocyanin extracts. Further clinical investigations, preferably with direct comparisons, are needed to validate these findings and elucidate the nuanced interplay between anthocyanins and food matrices, informing future research directions and practical recommendations.

Characterisation of the hydrogen sulfide system in early diabetic kidney disease.

A deficiency in hydrogen sulfide has been implicated in the development and progression of diabetic chronic kidney disease. The purpose of this study was to determine the effect of diabetes on the H2S system in early-stage diabetic kidney disease. We characterised gene and protein expression profile of the enzymes that regulate H2S production and degradation, and H2S production capacity, in the kidney from 10-week-old C57BL6Jdb/db mice (n = 6), in age-matched heterozygous controls (n = 7), and in primary endothelial cells (HUVECs) exposed to high glucose. In db/db mice, renal H2S levels were significantly reduced (P = 0.009). Protein expression of the H2S production enzymes was differentially affected by diabetes: cystathionine ß-synthase (CBS) was significantly lower in both db/db mice and high glucose-treated HUVECs (P < 0.0001; P = 0.0318) whereas 3-mercatopyruvate sulfurtransferase (3-MST) expression was higher in the db/db kidney (P < 0.0001), yet lower in the HUVECs (P = 0.0001). Diabetes had no effect on the expression of cystathionine γ-lyase (CSE) in the db/db kidney (P = ns) but was associated with reduced expression in the HUVECs (P = 0.0004). Protein expression of degradation enzyme sulfide quinone reductase (SQOR) was significantly higher in db/db kidney (P = 0.048) and lower in the high glucose-treated HUVECs (P = 0.008). Immunofluorescence studies revealed differential localisation of the H2S enzymes in the kidney, including both tubular and vascular localisation, suggestive of functionally distinct actions in the kidney. The results of this study provide foundational knowledge for future research looking at the H2S system in both kidney physiology and the aetiology of chronic diabetic kidney disease.

Advanced Glycation End-Products and Their Effects on Gut Health.

Dietary advanced glycation end-products (AGEs) are a heterogeneous group of compounds formed when reducing sugars are heated with proteins, amino acids, or lipids at high temperatures for a prolonged period. The presence and accumulation of AGEs in numerous cell types and tissues are known to be prevalent in the pathology of many diseases. Modern diets, which contain a high proportion of processed foods and therefore a high level of AGE, cause deleterious effects leading to a multitude of unregulated intracellular and extracellular signalling and inflammatory pathways. Currently, many studies focus on investigating the chemical and structural aspects of AGEs and how they affect the metabolism and the cardiovascular and renal systems. Studies have also shown that AGEs affect the digestive system. However, there is no complete picture of the implication of AGEs in this area. The gastrointestinal tract is not only the first and principal site for the digestion and absorption of dietary AGEs but also one of the most susceptible organs to AGEs, which may exert many local and systemic effects. In this review, we summarise the current evidence of the association between a high-AGE diet and poor health outcomes, with a special focus on the relationship between dietary AGEs and alterations in the gastrointestinal structure, modifications in enteric neurons, and microbiota reshaping.

Prior degree and academic performance in medical school: evidence for prioritising health students and moving away from a bio-medical science-focused entry stream.

BACKGROUND: Given the importance of the selection process, many medical schools are reviewing their selection criteria. The traditional pathway for post-graduate medicine has been from science-based undergraduate degrees, however some programs are expanding their criteria. In this study we investigated academic success across all years and themes of the Deakin University medical degree, based on the type of degree undertaken prior to admission. We evaluated whether the traditional pathway of biomedical science into medicine should remain the undergraduate degree of choice, or whether other disciplines should be encouraged. METHODS: Data from 1159 students entering the degree from 2008 to 2016 was collected including undergraduate degree, grade point average (GPA), Graduate Medical Schools Admission Test (GAMSAT) score and academic outcomes during the 4 years of the degree. Z-scores were calculated for each assessment within each cohort and analysed using a one sample t-test to determine if they differed from the cohort average. Z-scores between groups were analysed by 1-way ANOVA with LSD post-hoc analysis correcting for multiple comparisons. RESULTS: The majority of students had Science (34.3%) or Biomedical Science (31.0%) backgrounds. 27.9% of students had a Health-related undergraduate degree with smaller numbers of students from Business (3.5%) and Humanities (3.4%) backgrounds. At entry, GPA and GAMSAT scores varied significantly with Biomedical Science and Science students having significantly higher scores than Health students. Health students consistently outperformed students from other disciplines in all themes while Biomedical Science students underperformed. CONCLUSIONS: Our data suggest that a Health-related undergraduate degree results in the best performance throughout medical school, whereas a Biomedical Science background is associated with lower performance. These findings challenge the traditional Biomedical Science pathway into medicine and suggest that a health background might be more favourable when determining the selection criteria for graduate entry into medicine.

Vasoactivity of nitrite in the iliac artery of the toad Rhinella marina.

Nitrite ([Formula: see text]) causes vasodilation in mammals due to the formation of (nitric oxide) NO by endogenous [Formula: see text] reduction in the vascular wall. In this study, we determined if a similar mechanism operates in amphibians. Dual-wire myography of the iliac artery from Rhinella marina showed that applied [Formula: see text] caused a concentration-dependent vasodilation in normoxia (21% O2; EC50: 438 µM). Hypoxia (0.63% O2) significantly increased the maximal dilation to [Formula: see text] by 5% ( P = 0.0398). The addition of oxyhemoglobin significantly increased the EC50 ( P = 0.0144; EC50: 2,236 µM) but did not affect the maximal vasodilation. In contrast, partially deoxygenated hemoglobin (90% desaturation) did not affect the EC50 ( P = 0.1189) but significantly ( P = 0.0012) increased the maximal dilation to [Formula: see text] by 11%. The soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) completely abolished the response to [Formula: see text] ( P < 0.0001), and of the nitric oxide synthase inhibitors, only N5-(1-imino-3-butenyl)-l-ornithine (vinyl-l-NIO; P = 0.0028) significantly reduced the [Formula: see text] vasodilation. The xanthine oxidoreductase inhibitor allopurinol ( P = 0.927), the nitric oxide-scavenger 2-(4-carboxyphenyl)-4,5-dihydro-4,4,5,5-tetramethyl-1H-imidazolyl-1-oxy-3-oxide (C-PTIO; P = 0.478), and disruption of the endothelium ( P = 0.094) did not affect the [Formula: see text] vasodilation. Incubation of iliac arteries with 1 mM [Formula: see text] did not a cause a change in the cGMP concentration (P = 0.407). Plasma [Formula: see text] was found to be 0.86 ± 0.20 µmol/l, while nitrate ([Formula: see text]) was 19.55 ± 2.55 µmol/l. Both cygb and ngb mRNAs were expressed in the iliac artery, and it is possible that these globins facilitate [Formula: see text] reduction in hypoxia. In addition, [Formula: see text] intracellular disproportionation processes could be important in the generation of NO from [Formula: see text].

Dexamethasone increases production of C-type natriuretic peptide in the sheep brain.

Although C-type natriuretic peptide (CNP) has high abundance in brain tissues and cerebrospinal fluid (CSF), the source and possible factors regulating its secretion within the central nervous system (CNS) are unknown. Here we report the dynamic effects of a single IV bolus of dexamethasone or saline solution on plasma, CSF, CNS and pituitary tissue content of CNP products in adult sheep, along with changes in CNP gene expression in selected tissues. Both CNP and NTproCNP (the amino-terminal product of proCNP) in plasma and CSF showed dose-responsive increases lasting 12-16 h after dexamethasone, whereas other natriuretic peptides were unaffected. CNS tissue concentrations of CNP and NTproCNP were increased by dexamethasone in all of the 12 regions examined. Abundance was highest in limbic tissues, pons and medulla oblongata. Relative to controls, CNP gene expression (NPPC) was upregulated by dexamethasone in 5 of 7 brain tissues examined. Patterns of responses differed in pituitary tissue. Whereas the abundance of CNP in both lobes of the pituitary gland greatly exceeded that of brain tissues, neither CNP nor NTproCNP concentration was affected by dexamethasone, despite an increase in NPPC expression. This is the first report of enhanced production and secretion of CNP in brain tissues in response to a corticosteroid. Activation of CNP secretion within CNS tissues by dexamethasone, not exhibited by other natriuretic peptides, suggests an important role for CNP in settings of acute stress. Differential findings in pituitary tissues likely relate to altered processing of proCNP storage and secretion.

Effect of cortisol on C-type natriuretic peptide in ovine pregnancy: differential responses in fetal and placental tissues.

We have used aminoterminal pro C-type natriuretic peptide (NTproCNP)--a stable marker of CNP secretion--to study the effect of cortisol on CNP secretion and fetal growth. In ovine pregnancy, maternal plasma NTproCNP (largely sourced from the placenta) increases at the end of the first trimester and then decreases abruptly preterm during the phase of fetal surge in cortisol secretion. Postulating that increases in cortisol, as occurs in the fetal or maternal circulation in late pregnancy, will reduce CNP secretion, we studied the fetal and maternal responses in NTproCNP to sustained low-dose infusions of cortisol (1.2 mg/d/kg for 11 d) delivered to the fetus from d 117 gestation. Fetal plasma NTproCNP was progressively reduced during fetal cortisol infusions, whereas fetal girth growth was unchanged. In contrast, maternal NTproCNP was unaffected by cortisol. We conclude that fetal but not placental tissue production of CNP is reduced by small increments in fetal cortisol. Failure to reduce maternal NTproCNP may relate to the continuing presence of the placental barrier to cortisol at this stage of pregnancy.

C-type natriuretic peptide forms in pregnancy: maternal plasma profiles during ovine gestation correlate with placental and fetal maturation.

Circulating concentrations of C-type natriuretic peptide (CNP) and a related amino terminal fragment (NTproCNP) were measured at weekly intervals from preconception to 3 wk postpartum in ewes with twins (n = 8) and nonpregnant ewes (n = 8). In contrast to low and stable values in nonpregnant ewes (CNP, 0.75 +/- 0.08; NTproCNP, 22 +/- 2 pmol/liter), CNP forms increased abruptly at 40-50 d of gestation and rose to peak values (CNP, 31 +/- 5, NTproCNP, 270 +/- 16 pmol/liter) at about d 120. Approximately 7 d prepartum, the concentration of both CNP forms fell precipitously to preconception values immediately postpartum. In separate studies, circulating maternal CNP forms were positively related to fetal number at d 120. Consistent with a major contribution from the placenta to circulating levels, the concentrations of CNP forms were elevated in the placentome (cotyledon: CNP, 18 +/- 4, NTproCNP, 52 +/- 10 pmol/g; caruncle: CNP, 13 +/- 3, NTproCNP, 31 +/- 6 pmol/g) and much higher than those of intercaruncular uterine tissue (CNP, 0.19 +/- 0.05, NTproCNP, 0.98 +/- 0.2 pmol/g) in late-gestation ewes (P < 0.001, n = 4). These distinctive patterns of maternal plasma CNP forms, positive relation with fetal number, and greatly elevated protein concentrations in the placentome demonstrate the hormone's strong relation to placental and fetal maturation. The findings provide a firm basis for future studies of the functional role of CNP in fetal-maternal welfare.