Effects of low-sodium bread on dietary compliance and fecal cultivable bacteria in a randomized controlled pilot trial in hypertensive subjects

High salt intake and compliance to low-sodium (LS) diets are critical in hypertension. Salt reduction in processed foods can help to achieve the target sodium intake. To verify the hypothesis that an innovative LS formulation of a traditional bread could result in a reduction of sodium intake and blood pressure, we performed a 6-month randomized controlled pilot trial on hypertensive patients. We additionally explored the effects of sodium restriction on blood pressure and fecal cultivable bacteria.Fifty-seven patients were randomized in three groups. Group A (n = 19) followed a free diet using standard bread (750 mg Na/100 g), group B (n = 18) followed a LS diet (2300 mg Na/die) using standard bread, group C (n = 20) followed a LS diet (2300 mg Na/die) using LS bread (280 mg Na/100 g). We measured 24-h urinary sodium, blood pressure, routine parameters, fecal microbial counts (26 patients).After 6 months, as compared to group A, group C showed a reduction of 24-h urinary sodium excretion (-908 mg/24 h), diastolic pressure (-9 mmHg) and microbial counts of Bacteroides, Porphyromonas, Prevotella, Enterobacteriaceae, Staphylococcus, Micrococcus. These results suggest that LS bread could increase the adherence to a LS diet, reducing sodium excretion, diastolic pressure and abundance of some fecal cultivable bacteria.Trial registration Registration nr. NCT03127553, on 25/04/2017.

Obesity-Related Chronic Kidney Disease: Principal Mechanisms and New Approaches in Nutritional Management

Obesity is the epidemic of our era and its incidence is supposed to increase by more than 30% by 2030. It is commonly defined as a chronic and metabolic disease with an excessive accumulation of body fat in relation to fat-free mass, both in terms of quantity and distribution at specific points on the body. The effects of obesity have an important impact on different clinical areas, particularly endocrinology, cardiology, and nephrology. Indeed, increased rates of obesity have been associated with increased risk of cardiovascular disease (CVD), cancer, type 2 diabetes (T2D), dyslipidemia, hypertension, renal diseases, and neurocognitive impairment. Obesity-related chronic kidney disease (CKD) has been ascribed to intrarenal fat accumulation along the proximal tubule, glomeruli, renal sinus, and around the kidney capsule, and to hemodynamic changes with hyperfiltration, albuminuria, and impaired glomerular filtration rate. In addition, hypertension, dyslipidemia, and diabetes, which arise as a consequence of overweight, contribute to amplifying renal dysfunction in both the native and transplanted kidney. Overall, several mechanisms are closely related to the onset and progression of CKD in the general population, including changes in renal hemodynamics, neurohumoral pathways, renal adiposity, local and systemic inflammation, dysbiosis of microbiota, insulin resistance, and fibrotic process. Unfortunately, there are no clinical practice guidelines for the management of patients with obesity-related CKD. Therefore, dietary management is based on the clinical practice guidelines for the nutritional care of adults with CKD, developed and published by the National Kidney Foundation, Kidney Disease Outcome Quality Initiative and common recommendations for the healthy population. Optimal nutritional management of these patients should follow the guidelines of the Mediterranean diet, which is known to be associated with a lower incidence of CVD and beneficial effects on chronic diseases such as diabetes, obesity, and cognitive health. Mediterranean-style diets are often unsuccessful in promoting efficient weight loss, especially in patients with altered glucose metabolism. For this purpose, this review also discusses the use of non-classical weight loss approaches in CKD, including intermittent fasting and ketogenic diet to contrast the onset and progression of obesity-related CKD.

An Innovative Synbiotic Formulation Decreases Free Serum Indoxyl Sulfate, Small Intestine Permeability and Ameliorates Gastrointestinal Symptoms in a Randomized Pilot Trial in Stage IIIb-IV CKD Patients

Proteolytic dysbiosis of the gut microbiota has been recognized as both a typical feature of chronic kidney disease (CKD) and a risk factor for its progression. Blood accumulation of gut-derived uremic toxins (UTs) like indoxyl sulfate (IS) and p-cresyl sulfate (PCS), intestinal permeability and constipation are typical features accompanying CKD progression and triggering chronic inflammation. In order to verify the efficacy of the innovative synbiotic formulation NATUREN G^® in modulating the levels of circulating UTs, intestinal permeability and gastrointestinal symptoms, we set up a randomized, single-blind, placebo-controlled, pilot trial in stage IIIb-IV CKD patients and in healthy controls. Two-month administration of the synbiotic resulted in a decrease of free IS, as compared with the placebo-treated arm, only in the CKD group. The other UTs did not significantly change, although different trends in time (increase in the placebo arm and decrease in the synbiotic arm) were observed. Moreover, after supplementation, reduction of small intestinal permeability and amelioration of abdominal pain and constipation syndromes were observed only in the CKD group. The obtained results suggest the specificity of action of NATUREN G^® in CKD and justify further validation in a wider study population.

Ketoanalogs' Effects on Intestinal Microbiota Modulation and Uremic Toxins Serum Levels in Chronic Kidney Disease (Medika2 Study)

Nutritional therapy (NT) is a therapeutic option in the conservative treatment of chronic kidney disease (CKD) patients to delay the start of dialysis. The aim of this study was to evaluate the specific effect of ketoanalogs (KA)-supplemented diets for gut microbiota modulation. In a previous study we observed that the Mediterranean diet (MD) and a KA-supplemented very-low-protein diet (VLPD) modulated beneficially gut microbiota, reducing indoxyl- and p-cresyl-sulfate (IS, PCS) serum levels, and ameliorating the intestinal permeability in CKD patients. In the current study, we added a third diet regimen consisting of KA-supplemented MD. Forty-three patients with CKD grades 3B–4 continuing the crossover clinical trial were assigned to six months of KA-supplemented MD (MD + KA). Compared to MD, KA-supplementation in MD + KA determined (i) a decrease of Clostridiaceae, Methanobacteriaceae, Prevotellaceae, and Lactobacillaceae while Bacteroidaceae and Lachnospiraceae increased; (ii) a reduction of total and free IS and PCS compared to a free diet (FD)—more than the MD, but not as effectively as the VLPD. These results further clarify the driving role of urea levels in regulating gut integrity status and demonstrating that the reduction of azotemia produced by KA-supplemented VLPD was more effective than KA-supplemented MD in gut microbiota modulation mainly due to the effect of the drastic reduction of protein intake rather than the effect of KA.

Gut Microbiota, the Immune System, and Cytotoxic T Lymphocytes

Gut microbiota, the largest microbial community living in the human body, exerts a variety of metabolic, structural, and functional actions. In particular, it is essential for the full immune system development and maturation, as demonstrated by studies on germ-free animals, showing immune impairment at different levels. Gut microbiota shapes the immune responses by promoting immune tolerance toward food antigens and commensals in the steady state. This process is orchestrated by a complex network of both microbial and human cells and molecular mediators. Microbiota eubiosis is fundamental in establishing a correct balance between tolerance and immunity. Contrarily, microbiota dysbiosis is correlated with alterations in the immune balance, as evidenced in intestinal pathologies characterized by aberrant immune responses, such as inflammatory bowel disease and celiac disease, in which either break of tolerance against commensals or microbial dysbiosis is reported. On the other hand, a role for gut microbiota in stimulating the cytotoxic immune response in contexts of immunosuppression, like the ones featuring tumors and vaccinations, is emerging. The bifaceted role of gut microbiota in the delicate balance between tolerance and immunity could be exploited in order to develop pioneering therapeutic strategies, complementary to the pharmacological ones, thus representing a field worthy of further studies specifically focused on this topic.

Protein-Bound Uremic Toxins and Immunity

Protein-bound uremic toxins (PBUTs) are bioactive microbiota metabolites originated exclusively from protein fermentation of the bacterial community resident within the gut microbiota, whose composition and function is profoundly different in the chronic kidney disease (CKD) population. PBUTs accumulate in the later stages of CKD because they cannot be efficiently removed by conventional hemodialysis due to their high binding affinity for albumin, worsening their toxic effects, especially at the cardiovascular level. The accumulation of uremic toxins, along with oxidative stress products and pro-inflammatory cytokines, characterizes the uremic status of CKD patients which is increasingly associated to a state of immune dysfunction including both immune activation and immunodepression. Furthermore, the links between immune activation and cardiovascular disease (CVD), and between immunodepression and infection diseases, which are the two major complications of CKD, are becoming more and more evident. This review summarizes and discusses the current state of knowledge on the role of the main PBUTs, namely indoxyl sulfate and p-cresyl sulfate, as regulators of immune response in CKD, in order to understand whether a microbiota modulation may be useful in the management of its main complications, CVD, and infections. Summarizing the direct effects of PBUT on immune system we may conclude that PCS seemed to be associated to an immune deficiency status of CKD mainly related to the adaptative immune response, while IS seemed to reflect the activation of both innate and adaptative immune systems likely responsible of the CKD-associated inflammation. However, the exact role of IS and PCS on immunity modulation in physiological and pathological state still needs in-depth investigation, particularly in vivo studies.

Nutritional therapy reduces protein carbamylation through urea lowering in chronic kidney disease

Background

Protein carbamylation is one of the non-enzymatic reactions involved in protein molecular ageing. We sought to investigate the relationship between urea levels and protein carbamylation, and whether a Mediterranean diet (MD) and a very low protein diet (VLPD) reduce protein carbamylation through reduction in urea levels in patients with chronic kidney disease (CKD).

Methods

This is a prospective, randomized, crossover controlled trial that investigated 60 patients with CKD grades 3B-4 (46 males, mean age of 67 years). The enrolled CKD patients were randomly assigned (1:1) to two different nutritional treatment arms: (i) 3 months of free diet (FD), 6 months of VLPD, 3 months of FD and 6 months of MD; and (ii) 3 months of FD, 6 months of MD, 3 months of FD and 6 months of VLPD. Blood levels of lysine (Lys) and homocitrulline (Hcit) and their ratio were used as markers of cyanate levels. Due to a lack of pre-existing data on the potential effects of different dietary regimens and in light of the exploratory nature of the study, no formal sample size estimation was carried out.

Results

At study completion, lower diastolic blood pressure and decreased serum levels of urea, sodium, phosphorus and parathyroid hormone, but higher serum levels of bicarbonate and haemoglobin, were noted with MD and VLPD. When compared with FD, both MD and VLPD were also associated with a decrease in serum Hcit levels and Hcit/Lys ratios (P < 0.001). Notably, reductions in urea levels correlated with substantial reductions in Hcit levels (R2 = 0.16 and 0.17 for VLPD and MD, respectively).

Conclusion

In conclusion, nutritional treatments that significantly decrease serum levels of urea are associated with reduced protein carbamylation.

[Nutritional diet therapy in the management of the patient with Chronic Kidney Disease in advanced phase to delay the beginning and reduce the frequency of dialysis. An option also in the pre-emptive transplant program]

The Italian nephrology has a long tradition and experience in the field of dietetic-nutritional therapy (DNT), which is an important component in the conservative management of the patient suffering from a chronic kidney disease, which precedes and integrates the pharmacological therapies. The objectives of DNT include the maintenance of an optimal nutritional status, the prevention and / or correction of signs, symptoms and complications of chronic renal failure and, possibly, the delay in starting of dialysis. The DNT includes modulation of protein intake, adequacy of caloric intake, control of sodium and potassium intake, and reduction of phosphorus intake. For all dietary-nutritional therapies, and in particular those aimed at the patient with chronic renal failure, the problem of patient adherence to the dietetic-nutritional scheme is a key element for the success and safety of the DNT and it can be favored by an interdisciplinary and multi-professional approach of information, education, dietary prescription and follow-up. This consensus document, which defines twenty (20) essential points of the nutritional approach to patients with advanced chronic renal failure, has been written, discussed and shared by the Italian nephrologists together with representatives of dietitians (ANDID) and patients (ANED).

Nutrients, Nutraceuticals, and Xenobiotics Affecting Renal Health

Chronic kidney disease (CKD) affects 8–16% of the population worldwide. In developed countries, the most important risk factors for CKD are diabetes, hypertension, and obesity, calling into question the importance of educating and acting on lifestyles and nutrition. A balanced diet and supplementation can indeed support the maintenance of a general health status, including preservation of renal function, and can help to manage and curb the main risk factors for renal damage. While the concept of protein and salt restriction in nephrology is historically acknowledged, the role of some nutrients in renal health and the importance of nutrition as a preventative measure for renal care are less known. In this narrative review, we provide an overview of the demonstrated and potential actions of some selected nutrients, nutraceuticals, and xenobiotics on renal health and function. The direct and indirect effects of fiber, protein, fatty acids, curcumin, steviol glycosides, green tea, coffee, nitrates, nitrites, and alcohol on kidney health are reviewed here. In view of functional and personalized nutrition, understanding the renal and systemic effects of dietary components is essential since many chronic conditions, including CKD, are related to systemic dysfunctions such as chronic low-grade inflammation.

Microbiota metabolites: Pivotal players of cardiovascular damage in chronic kidney disease

In chronic kidney disease (CKD), cardiovascular (CV) damage is present in parallel which leads to an increased risk of CV disease. Both traditional and non-traditional risk factors contribute to CV damage in CKD. The systemic role of the microbiota as a central player in the pathophysiology of many organs is progressively emerging in the literature: the microbiota is indeed involved in a complex, bi-directional network between many organs, including the kidney and heart connection, although many of these relationships still need to be elucidated through in-depth mechanistic studies. The aim of this review is to provide evidence that microbiota metabolites influence non-traditional risk factors, such as inflammation and endothelial dysfunction in CKD-associated CV damage. Here, we report our current understanding and hypotheses on the gut-kidney and gut-heart axes and provide details on the potential mechanisms mediated by microbial metabolites. More specifically, we summarize some novel hypotheses linking the microbiota to blood pressure regulation and hypertension. We also emphasise the idea that the nutritional management of CKD should be redesigned and include the new findings from research on the intrinsic plasticity of the microbiota and its metabolites in response to food intake. The need is felt to integrate the classical salt and protein restriction approach for CKD patients with foods that enhance intestinal wellness. Finally, we discuss the new perspectives, especially the importance of taking care of the microbiota in order to prevent the risk of developing CKD and hypertension, as well as the still not tested but very promising CKD innovative treatments, such as postbiotic supplementation and bacteriotherapy. This interesting area of research offers potential complementary approaches to the management of CKD and CV damage assuming that the causal mechanisms underlying the gut-kidney and gut-heart axes are clarified. This will pave the way to the design of new personalized therapies targeting gut microbiota.

Aumento da sustentabilidade da produção de raças suínas locais através do uso de rótulos de qualidade – estudo de caso e desenvolvimento de uma marca comercial no projecto TREASURE

O interesse pelos recursos genéticos tradicionais, neste caso de raças suínas locais, tem crescido nas últimas décadas. No entanto, a maior parte das raças locais necessita, ainda, de ser subsidiada para garantir a sua conservação. Contudo, a melhor estratégia a seguir parece-nos ser garantir que essas raças atinjam autossustentabilidade o que será possível com uma estratégia de marketing eficiente para os seus produtos. A maioria das raças estudadas no projeto TREASURE são inexploradas, portanto a ambição é criar uma marca comercial coletiva (trademark) que servisse de “chapéu” que agregasse todas as raças e criasse valor acrescentado para os seus produtos. Os principais aspetos socioeconómicos relacionados com a implementação da marca comercial coletiva incluem os direitos, responsabilidades, e valor acrescentado expectável para os seus utilizadores finais. Baseados nos resultados obtidos num inquérito interno realizado no TREASUE, identificaram-se as principais características dessa marca comercial colaborativa: 1) deve atrair utilizadores finais como os criadores, associações de criadores e processadores de carne; 2) deve ser desenvolvida e promovida por um comité operacional constituído por utilizadores finais sob a coordenação e supervisão do consórcio do TREASURE; 3) deve realçar que os recursos genéticos locais suínos são o ponto-chave comum, considerando também os sistemas de produção e a nutrição; 4) deve ser explorada a possível colaboração ou conflito com os produtos presentemente protegidos pela EU (PDO, PGI, TSG) de forma a promover melhor os produtos locais. Apresenta-se uma análise dos direitos de propriedade intelectual (IPR) no contexto das fileiras de suínos existentes na União Europeia e as perspetivas para a marca comercial TREASURE analisada.

Non-Traditional Aspects of Renal Diets: Focus on Fiber, Alkali and Vitamin K1 Intake

Renal diets for advanced chronic kidney disease (CKD) are structured to achieve a lower protein, phosphate and sodium intake, while supplying adequate energy. The aim of this nutritional intervention is to prevent or correct signs, symptoms and complications of renal insufficiency, delaying the start of dialysis and preserving nutritional status. This paper focuses on three additional aspects of renal diets that can play an important role in the management of CKD patients: the vitamin K1 and fiber content, and the alkalizing potential. We examined the energy and nutrients composition of four types of renal diets according to their protein content: normal diet (ND, 0.8 g protein/kg body weight (bw)), low protein diet (LPD, 0.6 g protein/kg bw), vegan diet (VD, 0.7 g protein/kg bw), very low protein diet (VLPD, 0.3 g protein/kg bw). Fiber content is much higher in the VD and in the VLPD than in the ND or LPD. Vitamin K1 content seems to follow the same trend, but vitamin K2 content, which could not be investigated, might have a different pattern. The net endogenous acid production (NEAP) value decreases from the ND and LPD to the vegetarian diets, namely VD and VLPD; the same finding occurred for the potential renal acid load (PRAL). In conclusion, renal diets may provide additional benefits, and this is the case of vegetarian diets. Namely, VD and VLPD also provide high amounts of fibers and Vitamin K1, with a very low acid load. These features may have favorable effects on Vitamin K1 status, intestinal microbiota and acid-base balance. Hence, we can speculate as to the potential beneficial effects on vascular calcification and bone disease, on protein metabolism, on colonic environment and circulating levels of microbial-derived uremic toxins. In the case of vegetarian diets, attention must be paid to serum potassium levels.

Intestinal Microbiota in Type 2 Diabetes and Chronic Kidney Disease

PURPOSE OF THE REVIEW

Diabetes mellitus is a major cause of kidney disease [chronic kidney disease (CKD) and end-stage renal disease (ESRD)] and are both characterized by an increased risk of cardiovascular events. Diabetes and kidney disease are also commonly associated with a chronic inflammatory state, which is now considered a non-traditional risk factor for atherosclerosis. In the case of type 2 diabetes mellitus (T2DM), inflammation is mainly a consequence of visceral obesity, while in the case of CKD or ESRD patients on dialysis, inflammation is caused by multiple factors, classically grouped as dialysis-related and non-dialysis-related. More recently, a key role has been credited to the intestinal microbiota in the pathogenesis of chronic inflammation present in both disease states. While many recent data on the intestinal microbiota and its relationship to chronic inflammation are available for CKD patients, very little is known regarding T2DM and patients with diabetic nephropathy. The aim of this review is to summarize and discuss the main pathophysiological issues of intestinal microbiota in patients with T2DM and CKD/ESRD.

RECENT FINDINGS

The presence of intestinal dysbiosis, along with increased intestinal permeability and high circulating levels of lipopolysaccharides, a condition known as "endotoxemia," characterize T2DM, CKD, and ESRD on dialysis. The hallmark of intestinal dysbiosis is a reduction of saccharolytic microbes mainly producing short-chain fatty acids (SCFA) and, in the case of CKD/ESRD, an increase in proteolytic microbes that produce different substances possibly related to uremic toxicity. Dysbiosis is associated with endotoxemia and chronic inflammation, with disruption of the intestinal barrier and depletion of beneficial bacteria producing SCFAs. T2DM and CKD/ESRD, whose coexistence is increasingly found in clinical practice, share similar negative effects on both intestinal microbiota and function. More studies are needed to characterize specific alterations of the intestinal microbiota in diabetic nephropathy and to assess possible effects of probiotic and prebiotic treatments in this setting.

Beta-Glucans Supplementation Associates with Reduction in P-Cresyl Sulfate Levels and Improved Endothelial Vascular Reactivity in Healthy Individuals

Background

Oat and barley beta-glucans are prebiotic fibers known for their cholesterol-lowering activity, but their action on the human gut microbiota metabolism is still under research. Although the induction of short-chain fatty acids (SCFA) following their ingestion has previously been reported, no study has investigated their effects on proteolytic uremic toxins p-cresyl sulfate (pCS) and indoxyl sulfate (IS) levels, while others have failed to demonstrate an effect on the endothelial function measured through flow-mediated dilation (FMD).

Objective

The aim of our study was to evaluate whether a nutritional intervention with a functional pasta enriched with beta-glucans could promote a saccharolytic shift on the gut microbial metabolism and improve FMD.

Methods

We carried out a pilot study on 26 healthy volunteers who underwent a 2-month dietary treatment including a daily administration of Granoro “Cuore Mio” pasta enriched with barley beta-glucans (3g/100g). Blood and urine routine parameters, serum pCS/IS and FMD were evaluated before and after the dietary treatment.

Results

The nutritional treatment significantly reduced LDL and total cholesterol, as expected. Moreover, following beta-glucans supplementation we observed a reduction of serum pCS levels and an increase of FMD, while IS serum levels remained unchanged.

Conclusions

We demonstrated that a beta-glucans dietary intervention in healthy volunteers correlates with a saccharolytic shift on the gut microbiota metabolism, as suggested by the decrease of pCS and the increase of SCFA, and associates with an improved endothelial reactivity. Our pilot study suggests, in addition to cholesterol, novel pCS-lowering properties of beta-glucans, worthy to be confirmed in large-scale trials and particularly in contexts where the reduction of the microbial-derived uremic toxin pCS is of critical importance, such as in chronic kidney disease.

BMP-2 induces a profibrotic phenotype in adult renal progenitor cells through Nox4 activation

Adult renal progenitor cells (ARPCs) isolated from the human kidney may contribute to repair featuring acute kidney injury (AKI). Bone morphogenetic proteins (BMPs) regulate differentiation, modeling, and regeneration processes in several tissues. The aim of this study was to evaluate the biological actions of BMP-2 in ARPCs in vitro and in vivo. BMP-2 was expressed in ARPCs of normal adult human kidneys, and it was upregulated in vivo after delayed graft function (DGF) of renal transplantation, a condition of AKI. ARPCs expressed BMP receptors, suggesting their potential responsiveness to BMP-2. Incubation of ARPCs with this growth factor enhanced reactive oxygen species (ROS) production, NADPH oxidase activity, and Nox4 protein expression. In vivo, Nox4 was localized in BMP-2-expressing CD133+ cells at the tubular level after DGF. BMP-2 incubation induced α-smooth muscle actin (SMA), collagen I, and fibronectin protein expression in ARPCs. Moreover, α-SMA colocalized with CD133 in vivo after DGF. The oxidative stimulus (H2O2) induced α-SMA expression in ARPCs, while the antioxidant N-acetyl-cysteine inhibited BMP-2-induced α-SMA expression. Nox4 silencing abolished BMP-2-induced NADPH oxidase activation and myofibroblastic induction. We showed that 1) ARPCs express BMP-2, 2) this expression is increased in a model of AKI; 3) BMP-2 may induce the commitment of ARPCs toward a myofibroblastic phenotype in vitro and in vivo; and 4) this profibrotic effect is mediated by Nox4 activation. Our findings suggest a novel mechanism linking AKI with progressive renal damage.

Bone morphogenetic protein-2 may represent the molecular link between oxidative stress and vascular stiffness in chronic kidney disease

Oxidative stress and vascular calcifications are emergent risk factors for the accelerated atherosclerosis process featuring chronic kidney disease (CKD). Vascular calcification is an active process similar to bone modelling, where BMP-2 may play a pathogenic role. Aim of our study was to investigate the link between oxidative stress, BMP-2 protein expression and vascular disease in CKD. We enrolled 85 CKD patients (K-DOQI stage II or higher) and 41 healthy individuals. 8-Oxo-7,8-dihydro-2'-deoxyguanosine (8-OHdG) was used as a marker of oxidative stress. Brachial-ankle pulse wave velocity (baPWV) was used as a measure of arterial stiffness. BMP-2 serum levels were significantly higher in CKD patients than in controls (p<0.0001). Serum 8-OHdG levels were significantly higher in CKD patients compared to controls (p<0.05). BMP-2 serum levels were inversely associated with eGFR (r=-0.3; p=0.01) and directly correlated with 8-OHdG serum concentrations (r=-0.3; p=0.03). Arterial stiffness was inversely correlated with eGFR (r=-0.4; p=0.001) and directly correlated with BMP-2 (r=0.3; p=0.03), 8-OHdG (r=0.4, p=0.02) and phosphorus serum levels (r=0.3; p=0.007). In a multiple regression model, phosphorus and BMP-2 were independently correlated with baPWV. In vitro exposure to H(2)O(2) induced a time and dose-dependent increase in BMP-2 expression in an immortalized endothelial cell line. Moreover, H(2)O(2) pre-incubation of cultured vascular smooth muscle cell enhanced the BMP-2-induced up-regulation of ALPL, an osteoblastic phenotype marker. Our data suggest that in CKD BMP-2 may represent the molecular link between oxidative stress and arterial stiffness due to vascular calcification.

Opioid agonist/antagonist effect of naloxone in modulating rabbit jejunum contractility in vitro

Opioid peptides are the most effective drugs in controlling pain; their action is elicited by binding to specific membrane receptors. The gastrointestinal tract represents, after the nervous system, the site in which the opioid receptors are expressed at high levels. The opioid agonist morphine has a significant inhibitory effect on intestinal motility, this action is blocked by naloxone an opioid antagonist mainly active at mu and kappa receptors. In this study the presence of mu opioid receptor on rabbit jejunum was investigated by western blot. The effects of beta-endorphin, the endogenous opioid peptide with the highest affinity to the mu opioid receptor and those of naloxone on spontaneous rabbit jejunum contractions were evaluated. Beta-endorphin (10(-6) M) showed a relaxant effect on jejunum contractility while naloxone showed a dual effect inducing an increase of spontaneous contractility at low concentrations (10(-6) M, 10(-7) M, 10(-8) M) and a decrease when high concentrations (10(-3) M, 10(-4) M, 10(-5) M) were utilized. The obtained results demonstrate that mu opioid receptor is expressed in rabbit jejunum and suggest that this receptor may be involved in mediating the effects of both opioid agonist and antagonist on jejunum contractions.