Long term consumption of high fructose and high salt diet did not induce blood pressure elevation in female mice. Is estrogen protective against dietary-induced high blood pressure?

Introduction: High fructose and high salt (HFHS) consumption are linked to hypertension, which is now the leading cause of death worldwide. Results from a previous study showed that the effect of HFHS on blood pressure (BP) is dependent on the concentration and duration of consumption. Sex differences in BP regulation are partially attributed to the effects of sex steroids on key renal sodium transporters.Hypothesis: We hypothesized that HFHS would induce BP elevation in male and female mice, however, females will have higher expression of renal NCC/NKCC during long-term HFHS diet consumption.Methods: Four-week-old male and female CD-1 mice (n= 6/group) were placed in metabolic cages and consumed standard chow and water for seven days, followed by 3months of 4% sodium chloride (NaCl) diet and a drinking solution of 1% NaCl and 20% fructose. Separate mice on the same diet in bins were sacrificed and kidneys extracted at the end of the first week, first and second months, and used for molecular studies.Results: Females expressed higher mRNA levels of NCC and NKCC throughout the study with fold difference of two or higher. Systolic BP averaged weekly and analyzed via ANOVA showed no sex difference in BP from baseline to the third month. Males showed an increase in BP in the third month compared to baseline (123.6 ± 3.6mmHg and 106.3 ± 5.4mmHg, P< 0.5 respectively). There were no sex differences in sodium retention.Conclusion: Females have protection against HFHS induced BP elevation and estrogen may have a protective role

Effects of estrogen on blood pressure and salt and water excretion during a ten-day Angiotesin ll infusion period in ovariectomized mice

Introduction: Premenopausal women are protected from cardiovascular disease compared to age-matched men. Estrogen (E2) plays important roles in these protective mechanisms.Purpose: Our goal was to determine if E2 reduces angiotensin II (AngII)-induced elevation in blood pressure in ovariectomized (OVX) mice. We also hypothesized that E2 affects renal excretion of water and sodium.Methods: Four-week-old CD-1 OVX mice were placed in metabolic cages for a five-day baseline period followed by implantation of an Alzet osmotic pump containing either vehicle or AngII (1 µg/kg/min) and either a placebo or 0.7mg E2 pellet. Measurements of water intake (WI, ml/day), urine volume (UV, ml/day), and urine sodium excretion (UNaE, μEq/day) were recorded daily in the baseline and ten-day post-implantation periods in three groups of mice: vehicle-placebo (V-P), AngII-placebo (AngII-P), and AngII-E2 (n=4/group). Systolic blood pressure (SBP, mmHg) was determined via the tail-cuff technique.Results: Delta SBP (baseline vs AngII period) was higher in AngII-P but not significantly different from AngII-E2 mice, (33.1±3.5 vs 24.5±4.0, respectively). AngII-E2 mice compared to AngII-P mice had lower WI (4.2±0.02 vs 6.9±0.05, respectively, p<0.001), lower UV (1.3±0.02 vs 2.6±0.03, respectively, p<0.03), and lower UNaE (110.5±20.7 vs 199.7±10.8, respectively, p<0.003).Conclusion: E2 administration reduces WI, UV, and UNaE during a ten-day AngII-infusion in OVX mice. E2 did not significantly reduce SBP. Studies of longer duration are underway to investigate the important E2-induced mechanisms on blood pressure regulation

Effects of high salt diet on blood pressure and the renal handling of sodium

Introduction: The association between elevated dietary salt consumption and high blood pressure is well known. Hypertension carries elevated risk for stroke, cardiovascular disease, liver disease, and nervous disorders. Interestingly, sex differences in many areas of pathophysiology. Pre-menopausal women have shown to be protected against hypertension and renal diseases compared to age matched men. It is reasonable to expect that how the kidney handles sodium in presence of high-salt consumption plays a key role in sex differences. The purpose of this study was to determine sex differences in the renal handling of sodium in mice consuming a high-salt diet. We also investigated the effects of high-salt consumption on blood pressure in these mice.Methods: Intact male and female mice (n=6/group) consumed a high-salt (4%, HarlanTeklad) diet for 30 days. Mice were placed individually in metabolic cages where urine could be collected for volume and measurement of Na+ concentration. Urinary Na+ excretion (NAE, mg/day) was determined from daily measurements of urine sodium concentration and urine volume. Sodium intake (Nai, mg/day) was determined from daily food intake of 4% salt diet ad libitum. Blood pressure was measured daily via the tail-cuff method. Expression of key sodium transport proteins in the kidney was measured via real-time quantitative PCR.Results: From the data accumulated during the 30-day period of high salt consumption, female mice showed a significantly lower average of the output-to-input Na+ ratio (NAE/Nai) compared to male mice (53.3 ± 2.7 vs 68.1 ± 1.8, respectively, p<0.0001). Female mice showed lower mean blood pressure (MBP, mmHg) compared to male mice over the 30-day period (78.4 ± 1.0 vs 84.9 ± 1.2 respectively, <0.0005). Molecular expression of the key sodium transporter Na+ -2Cl- -K + (NKCC) in the thick ascending limb was over 5-fold higher in the female kidney.Conclusion: Interestingly, results from this study demonstrated that female mice retained more ingested sodium compared to male mice while on a high-salt diet. Moreover, female mice had lower MBP compared to male mice while on a high-salt diet. We suspect that sex steroids are playing important roles in the renal handling of sodium and in the control of blood pressure. This study suggests that females are protected from deleterious effects of high-salt consumption

Sex differences in protein excretion in mice consuming high protein diet

Background: Normally, the renal excretion of protein (or proteinuria) is absent or very small. Ingesting high-protein diets can elevate proteinuria and in the long term, increase the work on the kidney by increasing glomerular filtration and higher energy requirement to handle the protein. Sex differences in renal function are well known and thus, differences in proteinuria may exist. The purpose of this study was to determine if sex differences exist in proteinuria in mice consuming high protein diet and investigate the potential roles of the sex steroids 17beta-estrogen (E2) and testosterone.Methods: Healthy 3-4-week-old male and female intact and gonadectomized mice were used. Mice were placed in individual metabolic cages where the urine of each mouse could be collected and measured for protein concentration. Mice consumed a 40% casein protein diet for 25 days (normal protein = 20% protein). Some gonadectomized female mice received exogenous E2 and gonadectomized male mice received exogenous testosterone. Proteinuria was measured via dipstick measurement and protein excretion (mg/day) i.e., urine flow rate (ml/day) x urine protein concentration(mg/day).Results: Intact male mice had significantly higher proteinuria compared to intact female mice (5-10 mg/day vs 25-30 mg/day, p<0.001). Gonadectomized male and female mice had very low proteinuria (3- 5 mg/day). Gonadectomized testosterone-treated male mice had high proteinuria not different from the intact male mice. Gonadectomized E2-treated female mice had similar proteinuria compared to intact female mice and slightly though not significantly higher than gonadectomized placebo-treated female mice.Conclusion: The results of this study suggest that the male sex steroid induces high proteinuria in mice consuming high protein levels. The female sex steroid plays no role or only a minor role in proteinuria under these experimental conditions. Our results suggest that androgens may account for the higher incidence of kidney disease in males compared to age-matched pre-menopausal females

Properties of an acid-tolerant, persistent Cheddar cheese isolate, Lacticaseibacillus paracasei GCRL163

The distinctive flavours in hard cheeses are attributed largely to the activity of nonstarter lactic acid bacteria (NSLAB) which dominate the cheese matrix during maturation after lactose is consumed. Understanding how different strains of NSLAB survive, compete, and scavenge available nutrients is fundamental to selecting strains as potential adjunct starters which may influence product traits. Three Lacticaseibacillus paracasei isolates which dominated at different stages over 63-week maturation periods of Australian Cheddar cheeses had the same molecular biotype. They shared many phenotypic traits, including salt tolerance, optimum growth temperature, growth on N-acetylglucosamine and N-acetylgalactosamine plus delayed growth on D-ribose, carbon sources likely present in cheese due to bacterial autolysis. However, strains 124 and 163 (later named GCRL163) survived longer at low pH and grew on D-tagatose and D-mannitol, differentiating this phenotype from strain 122. When cultured on growth-limiting lactose (0.2%, wt/vol) in the presence of high concentrations of L-leucine and other amino acids, GCRL163 produced, and subsequently consumed lactate, forming acetic and formic acids, and demonstrated temporal accumulation of intermediates in pyruvate metabolism in long-term cultures. Strain GCRL163 grew in Tween 80-tryptone broths, a trait not shared by all L. casei-group dairy isolates screened in this study. Including citrate in this medium stimulated growth of GCRL163 above citrate alone, suggesting cometabolism of citrate and Tween 80. Proteomic analysis of cytosolic proteins indicated that growth in Tween 80 produced a higher stress state and increased relative abundance of three cell envelope proteinases (CEPs) (including PrtP and Dumpy), amongst over 230 differentially expressed proteins

A pilot dose-response study of the acute effects of haskap berry extract (Lonicera caerulea L.) on cognition, mood and blood pressure in older adults

Purpose Haskap (Lonicera caerulea L. or blue honeysuckle) is a plant native to the low-lying wet areas and mountains of Siberia and northeastern Asia, but is now cultivated in Canada. The dark blue berries are rich in anthocyanins, particularly cyanidin-3-O-glucoside. Previously, anthocyanin-rich fruits have been observed to benefit cognitive performance during the immediate postprandial period following a single acute dose. However, no study has currently examined the potential for haskap berries to influence cognitive performance. Here, we investigate the acute cognitive benefits of an anthocyanin-rich haskap berry extract. Methods A double-blind, counterbalanced, crossover intervention study compared the acute effects of three separate haskap berry extract doses, containing 100mg, 200mg, and 400mg anthocyanins, with a sugar-matched placebo. Participants were an opportunity sample of 20 older adults, aged 62-81 years. Measures of cognition, mood, and blood pressure were recorded at baseline and 1.5 hours postprandially. Results Compared to placebo, the 400mg dose elicited significantly lower diastolic blood pressure and heart rate. Both 200mg and 400mg doses elicited significantly higher word recall, with the 400mg dose also significantly improving word recognition scores, on an episodic memory task. However, mood, working memory and executive function task results were more equivocal. Conclusions The findings provide evidence for improvements in episodic memory and blood pressure following acute supplementation with haskap berry extract, with higher doses appearing most effective. The cognitive findings concur with previous literature that suggests episodic memory effects, and not executive function effects, are most prevalent in older adults following anthocyanin-rich berry supplementation. The blood pressure outcome is consistent with a vasodilatory mechanism of action

The Acid Test of Fluoride: How pH Modulates Toxicity

Background: It is not known why the ameloblasts responsible for dental enamel formation are uniquely sensitive to fluoride ($F^−$). Herein, we present a novel theory with supporting data to show that the low pH environment of maturating stage ameloblasts enhances their sensitivity to a given dose of $F^−$. Enamel formation is initiated in a neutral pH environment (secretory stage); however, the pH can fall to below 6.0 as most of the mineral precipitates (maturation stage). Low pH can facilitate entry of $F^−$ into cells. Here, we asked if $F^−$ was more toxic at low pH, as measured by increased cell stress and decreased cell function. Methodology/Principal Findings: Treatment of ameloblast-derived LS8 cells with $F^−$ at low pH reduced the threshold dose of $F^−$ required to phosphorylate stress-related proteins, PERK, eIF2α, JNK and c-jun. To assess protein secretion, LS8 cells were stably transduced with a secreted reporter, Gaussia luciferase, and secretion was quantified as a function of $F^−$ dose and pH. Luciferase secretion significantly decreased within 2 hr of $F^−$ treatment at low pH versus neutral pH, indicating increased functional toxicity. Rats given 100 ppm $F^−$ in their drinking water exhibited increased stress-mediated phosphorylation of eIF2α in maturation stage ameloblasts (pH<6.0) as compared to secretory stage ameloblasts (pH∼7.2). Intriguingly, $F^−$-treated rats demonstrated a striking decrease in transcripts expressed during the maturation stage of enamel development (Klk4 and Amtn). In contrast, the expression of secretory stage genes, AmelX, Ambn, Enam and Mmp20, was unaffected. Conclusions: The low pH environment of maturation stage ameloblasts facilitates the uptake of $F^−$, causing increased cell stress that compromises ameloblast function, resulting in dental fluorosis

Hypofibrinolysis in diabetes: a therapeutic target for the reduction of cardiovascular risk

An enhanced thrombotic environment and premature atherosclerosis are key factors for the increased cardiovascular risk in diabetes. The occlusive vascular thrombus, formed secondary to interactions between platelets and coagulation proteins, is composed of a skeleton of fibrin fibres with cellular elements embedded in this network. Diabetes is characterised by quantitative and qualitative changes in coagulation proteins, which collectively increase resistance to fibrinolysis, consequently augmenting thrombosis risk. Current long-term therapies to prevent arterial occlusion in diabetes are focussed on anti-platelet agents, a strategy that fails to address the contribution of coagulation proteins to the enhanced thrombotic milieu. Moreover, antiplatelet treatment is associated with bleeding complications, particularly with newer agents and more aggressive combination therapies, questioning the safety of this approach. Therefore, to safely control thrombosis risk in diabetes, an alternative approach is required with the fibrin network representing a credible therapeutic target. In the current review, we address diabetes-specific mechanistic pathways responsible for hypofibrinolysis including the role of clot structure, defects in the fibrinolytic system and increased incorporation of anti-fibrinolytic proteins into the clot. Future anti-thrombotic therapeutic options are discussed with special emphasis on the potential advantages of modulating incorporation of the anti-fibrinolytic proteins into fibrin networks. This latter approach carries theoretical advantages, including specificity for diabetes, ability to target a particular protein with a possible favourable risk of bleeding. The development of alternative treatment strategies to better control residual thrombosis risk in diabetes will help to reduce vascular events, which remain the main cause of mortality in this condition

Sex differences in blood pressure and renal handling of sodium in mice on a high salt and high fructose diet

Background: High consumption of either fructose or salt can have deleterious consequences on health and consuming high levels of both leads to serious health problems. Research demonstrates that important sex differences exist with respect to renal metabolism of high fructose intake which directly effects renal handling of sodium. The objective of this study was to investigate sex differences in blood pressure and renal handling of sodium in mice consuming a high-salt and high-fructose (HSHF) diet. We set out to determine if females are protected from high blood pressure when consuming HSHF.Methods: Healthy 4-week-old male and female mice (n=6/group) were placed in metabolic cages for six weeks. For the first week (baseline), all mice consumed a normal diet (0.25% salt) with water. Mice were then placed on the HSHF diet consisting of 4% salt chow with a drinking solution of 20% fructose and 1% NaCl for the next 4 weeks. This was followed by a recovery week with mice on the normal diet with water. Blood pressure was measured daily via the tail cuff technique and averaged weekly. Daily measurements of sodium intake and output were measured. Sodium intake (Nai, mEq/day) was calculated from daily food and fluid consumptionand output was measured by sodium excretion (Nae, mEq/day) (urine volume, ml/day x urine sodium concentration, mEq/day). Sodium concentration was measured using the EasyLyte Na/K analyzer. The ratio Nae/Nai indicates sodium retention. Real-time PCR was conducted using custom-made PCR arrays made by Qiagen SA Biosciences) designed with specific primers for mouse renal Na+ transporters.Results: Mean blood pressure (MBP) was not different between male and female mice in the baseline week and in the first week on HSHF diet. MBP significantly increased in female mice in the 2nd week on the HSHF diet whereas MBP increased in male mice only slightly from baseline. In the 3rd week on HSHF diet male MBP increased to that of the females and MBP in both sexes remained high in the 4th week. In the recovery week, MBP remained elevated in females whereas MBP in males decreased significantly (p<0.01 compared to females). Female mice showed higher sodium retention during the HSHF period via the Nae/Nai (62±5% vs 75±5%, p<0.001). Molecular expression of renal sodium transporters showed significantly higher expression of the NKCC and the NCC transporter in the female kidney.Conclusion: Results indicate that the HSHF diet significantly increased MBP in female and male mice. MBP in females increased before that in males and remained elevated during the recovery period whereas blood pressure decreased in males in the recovery period. Females had higher retention of sodium and higher expression of renal sodium transporters. We conclude that female mice are not protected from the HSHF dietary-induced increase in blood pressure. This study challenges the current position that females possess protective mechanisms against dietary induced increase in blood pressure