Rationale for a New Classification of Solutes of Interest in Chronic Kidney Disease and Hemodialysis.

A hallmark of chronic kidney disease is the retention of solutes that normally are eliminated by the kidneys. The current classification defines uremic toxins based on molecular weight and protein affinity. The retention of solutes is already detected in the early stages of the disease when patients are pauci-symptomatic or asymptomatic but the role of therapies to retard the loss of kidney function in patients with chronic kidney disease (e.g., modulators of the renin-angiotensin-aldosterone system, sodium-glucose cotransporter inhibitors) in reducing uremic toxins is poorly understood. Most of the research evaluating the impact of therapies to lower serum concentrations of those toxic compounds is carried out in patients with kidney failure already undergoing kidney replacement therapy. The removal of those molecules relies in physicochemical mass transfer phenomena, i.e., adsorption, diffusion, and convection. In the past 2 decades, the rise and broad adoption of blood purification strategies with enhanced convective properties, such as high-volume online hemodiafiltration and expanded hemodialysis, considerably amplified the ability to mechanically extract middle molecules (molecular weight >0.5 kDa) from the blood compartment. Nonetheless, the classification of uremic toxins has not evolved in parallel with dialysis advancements. Mounting evidence demonstrates the link between middle molecules with uremic symptoms, cardiovascular and mortality risks. An urgent need for updating the classification exists. Defining the causative relationship between specific solutes and specific clinical outcomes will promote the development of targeted therapies. In parallel, the inclusion of new pertinent dimensions to the classification like the influence of new dialysis membranes, sorbents, and intestinal chelators in the concentration of uremic toxins would improve the understanding of the pathogenesis of chronic kidney disease, setting the pace for future research in nephrology.

PPARγ partial agonist GQ-16 strongly represses a subset of genes in 3T3-L1 adipocytes.

Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor gamma (PPARγ) agonists that improve insulin resistance but trigger side effects such as weight gain, edema, congestive heart failure and bone loss. GQ-16 is a PPARγ partial agonist that improves glucose tolerance and insulin sensitivity in mouse models of obesity and diabetes without inducing weight gain or edema. It is not clear whether GQ-16 acts as a partial agonist at all PPARγ target genes, or whether it displays gene-selective actions. To determine how GQ-16 influences PPARγ activity on a gene by gene basis, we compared effects of rosiglitazone (Rosi) and GQ-16 in mature 3T3-L1 adipocytes using microarray and qRT-PCR. Rosi changed expression of 1156 genes in 3T3-L1, but GQ-16 only changed 89 genes. GQ-16 generally showed weak effects upon Rosi induced genes, consistent with partial agonist actions, but a subset of modestly Rosi induced and strongly repressed genes displayed disproportionately strong GQ-16 responses. PPARγ partial agonists MLR24 and SR1664 also exhibit disproportionately strong effects on transcriptional repression. We conclude that GQ-16 displays a continuum of weak partial agonist effects but efficiently represses some negatively regulated PPARγ responsive genes. Strong repressive effects could contribute to physiologic actions of GQ-16.

Nursing students admitted through the affirmative action system display similar performance in professional and academic trajectories to those from the regular path in a public school in Brazil.

OBJECTIVES: Affirmative action providing higher education access for socially vulnerable students has been implemented in several countries. However, these policies remain controversial. This study compares the performance of students admitted through the regular path and social quota systems, during and after completion of nursing education, in a public nursing school in Brazil. METHODS: This retrospective cohort study included all students admitted to nursing school at the School of Health Sciences (ESCS), Brazil, between 2009 and 2014, who were followed until May 2020. The first phase involved document analysis from the ESCS academic management system and Brazilian government agencies. In the second phase, a survey was conducted among the alumni. The social quota system criterion was public school attendance across all primary and secondary education levels. RESULTS: Of the 448 students included in the study, 178 (39.7%) were from the affirmative action and 270 (60.3%) from the regular path systems. Affirmative action students were older at the time of nursing school admission (p < 0.001) and took longer to be admitted to the nursing school (p < 0.001) after completing high school. There were no significant differences in the dropout rates and years to complete nursing school. In the second phase, 108 alumni answered the survey. No significant differences were found in their participation in the undergraduate scientific research program and university extension projects, attending residency programs, getting a master's degree and doctoral degree, monthly income, teaching activity, joining public service through a government job competition process, participation in management activities in the private and public health sector, and degree of job satisfaction. CONCLUSION: Our results revealed that affirmative action is a policy that contributes to the reduction of inequalities and guarantees the training of nursing professionals with a similar professional qualification received through affirmative action and regular path systems.

Prioritization of ICU beds with renal replacement therapy support by court order and mortality in a Brazilian metropolitan area.

The shortage of intensive care unit (ICU) resources, including equipment and supplies for renal replacement therapy (RRT), is a critical problem in several countries. This study aimed to assess hospital mortality and associated factors in patients treated in public hospitals of the Federal District, Brazil, who requested admission to ICU with renal replacement therapy support (ICU-RRT) in court. Retrospective cohort study that included 883 adult patients treated in public hospitals of the Federal District who requested ICU-RRT admission in court from January 2017 to December 2018. ICU-RRT was denied to 407 patients, which increased mortality (OR 3.33, 95% CI 2.39-4.56, p ≪ 0.01), especially in patients with priority level I/II (OR 1.02, 95% CI 1.01-1.04, p ≪ 0.01). Of the requests made in court, 450 were filed by patients with priority levels III/IV, and 44.7% of these were admitted to ICU-RRT. In admitted patients, priority level III priority level I/II was associated with a low mortality (OR 0.47, 95% CI 0.32-0.69, p < 0.01), and not. The admission of patients classified as priority levels III/IV to ICU-RRT considerably jeopardized the admission of patients with priority levels I/II to these settings. The results found open new avenues for organizing public policies and improving ICU-RRT triage.

Antiproliferative effects of metformin in cellular models of pheochromocytoma.

Pheochromocytomas (PCCs) are rare neuroendocrine tumors derived from adrenal medulla chromaffin cells. Malignancy and recurrence are rare but demand effective treatment. Metformin exerts antiproliferative effects in several cancer cell lines. We thus evaluated the effects of metformin on cell viability and proliferation, cellular respiration and AMPK-AKT-mTOR-HIFA proliferation pathway on a rat PCC cell line (PC12-Adh). We then addressed metformin's effects on the AMPK-AKT-mTOR-HIFA pathway on two human primary cultures: one from a VHL-mutant PCC and other from a sporadic PCC. Metformin (20 mM) inhibited PC12-Adh cell proliferation, and decreased oxygen consumption, ATP production and proton leak, in addition to loss of mitochondrial membrane potential. Further, metformin induced AMPK phosphorylation and impaired AMPK-PI3k-AKT-mTOR pathway activation. The mTOR pathway was also inhibited in human VHL-related PCC cells, however, in an AMPK-independent manner. Metformin-induced decrease of HIF1A levels was likely mediated by proteasomal degradation. Altogether our results suggest that metformin impairs PCC cellular proliferation.

Remodeling process in bone of aged rats in response to resistance training.

AIMS: We investigate the effects of RT on the mechanical function, gene, and protein expression of key factors involved in bone remodeling during aging. MAIN METHODS: Male rats of 3 and 21 months of age were randomly allocated into four groups (8 per group): young sedentary (YS), young trained (YT), old sedentary (OS), and old trained (OT). RT was performed three times per week (12 weeks). Bone tenacity and stiffness were measured by biomechanical tests and mRNA levels of COL1A1, MEPE, SOST, OPG, BMP-2, PPAR-y, MMP-2-9-13, and TIMP-1 were evaluated by quantitative PCR. COL1A1 protein and MMP-2 activity were detected by western blotting and zymography assays. KEY FINDINGS: Aging increased stiffness, while BMP-2, OPG, COL1A1 and MMP-2 mRNA levels reduced (OS vs YS; p ≤ 0.05). RT increased the tenacity of the femur and reduced PPAR-γ regardless of age (YT vs. YS; OT vs. OS; p ≤ 0.05). RT downregulated SOST mRNA levels only in the OT group (vs. OS group, p ≤ 0.05). RT mitigated the age-associated increase in MMP-9 mRNA levels (p ≤ 0.05). In young animals, upregulation in MEPE, MMP-13, TIMP-1 were observed after RT, as well an increase in COL1A1 protein and MMP-2 activity (p ≤ 0.05). SIGNIFICANCE: RT improved bone tenacity independent of aging, which is relevant for mechanical function, while, at protein levels, RT upregulated MMP-2 activity and collagen 1 only in young rats. This study highlights the importance of exercise on bone health and identifies specific molecular changes in response to RT. Our findings provide insights into the mechanisms involved in age-related changes.

Synthesis, biological evaluation and molecular modeling studies of arylidene-thiazolidinediones with potential hypoglycemic and hypolipidemic activities.

New arylidene-thiazolidinediones (ATZDs) were synthesized and evaluated in the alloxan-induced hyperglycemia mice model. The molecular target taken into consideration is the nuclear PPAR-gamma whose crystallographic structure is available on the PDB database as 2PRG. Thus the hypoglycemic and hypolipidemic activities of compounds were compared with the result of their docking after removal of the co-crystallized ligand present in the 2PRG structure. Molecular modeling studies were carried out using the Autodock 3.0.5 and ADT 1.1 programs.

In vitro Effects of Four Native Brazilian Medicinal Plants in CYP3A4 mRNA Gene Expression, Glutathione Levels, and P-Glycoprotein Activity.

Erythrina mulungu Benth. (Fabaceae), Cordia verbenacea A. DC. (Boraginaceae), Solanum paniculatum L. (Solanaceae) and Lippia sidoides Cham. (Verbenaceae) are medicinal plant species native to Brazil shortlisted by the Brazilian National Health System for future clinical use. However, nothing is known about their effects in metabolic and transporter proteins, which could potentially lead to herb-drug interactions (HDI). In this work, we assess non-toxic concentrations (100 µg/mL) of the plant infusions for their in vitro ability to modulate CYP3A4 mRNA gene expression and intracellular glutathione levels in HepG2 cells, as well as P-glycoprotein (P-gp) activity in vincristine-resistant Caco-2 cells (Caco-2 VCR). Their mechanisms of action were further studied by measuring the activation of human pregnane X receptor (hPXR) in transiently co-transfected HeLa cells and the inhibition of γ-glutamyl transferase (GGT) in HepG2 cells. Our results show that P-gp activity was not affected in any case and that only Solanum paniculatum was able to significantly change CYP3A4 mRNA gene expression (twofold decrease, p < 0.05), this being correlated with an antagonist effect upon hPXR (EC50 = 0.38 mg/mL). Total intracellular glutathione levels were significantly depleted by exposure to Solanum paniculatum (-44%, p < 0.001), Lippia sidoides (-12%, p < 0.05) and Cordia verbenacea (-47%, p < 0.001). The latter plant extract was able to decrease GGT activity (-48%, p < 0.01). In conclusion, this preclinical study shows that the administration of some of these herbal medicines may be able to cause disturbances to metabolic mechanisms in vitro. Although Erythrina mulungu appears safe in our tests, active pharmacovigilance is recommended for the other three species, especially in the case of Solanum paniculatum.

Idealized PPARγ-Based Therapies: Lessons from Bench and Bedside.

The incidence of type 2 (T2D) diabetes and other chronic conditions associated with insulin resistance is increasing at an alarming rate, underscoring the need for effective and safe therapeutic strategies. Peroxisome-proliferator-activated receptor gamma (PPARγ) has emerged as a critical regulator of glucose homeostasis, lipid homeostasis, and vascular inflammation. Currently marketed drugs targeting this receptor, the thiazolidinediones (TZDs), have proven benefits on insulin resistance and hyperglycemia associated with T2D. Unfortunately, they have been associated with long-term unfavorable effects on health, such as weight gain, plasma volume expansion, bone loss, cardiovascular toxicity, and possibly cancer, and these safety concerns have led to reduced interest for many PPARγ ligands. However, over the last years, data from human genetic studies, animal models, and studies with ligands have increased our understanding of PPARγ's actions and provided important insights into how ligand development strategies could be optimized to increase effectiveness and safety of PPARγ-based therapies.

Selenoprotein-related disease in a young girl caused by nonsense mutations in the SBP2 gene.

CONTEXT: Selenoproteins are essential for life, and their biosynthesis requires the incorporation of the rare amino acid selenocysteine (Sec) in a process mediated by the Sec insertion sequence-binding protein 2 (SBP2). Although SBP2 is considered a rate-limiting factor mediating Sec incorporation, there has been little evidence so far linking SBP2 dysfunction to widespread selenoprotein-related disease. OBJECTIVE: The objective of the study was to report the discovery of novel truncation mutations in the SBP2 gene (R120X/R770X) in a female adolescent and the clinical consequences of the combined deficiency of selenoproteins. SUBJECTS AND METHODS: A 12-yr-old girl who presented with a syndrome of abnormal thyroid hormone metabolism, delayed bone maturation, congenital myopathy, and impaired mental and motor coordination development and her family were studied. The coding region of the SBP2 gene was analyzed by sequencing, and gel shift assays were performed to address the in vitro binding properties of the mutant SBP2 protein. RESULTS: Serum levels of selenium and glutathione peroxidase in the proband were reduced, and selenoprotein P levels were undetectable. DNA sequencing of the SBP2 gene revealed a compound heterozygous mutation (R120X/R770X). The R120X mutation disrupted all functional motifs and the R770X inhibited the binding of SBP2 to Sec insertion sequence elements. Interestingly, selenium supplementation normalized serum selenium and glutathione peroxidase but not selenoprotein P levels and did not restore thyroid hormone metabolism dysfunction. CONCLUSIONS: This distinctive phenotype can only be explained by the combined deficiency of functionally important selenoproteins and pinpoints the clinical relevance of selenoproteins and selenium economy in human development.

Comparative effects of Stevia rebaudiana leaves and stevioside on glycaemia and hepatic gluconeogenesis.

The purpose of the present study was to compare the effect of the oral treatment (gavage) with Stevia rebaudiana (Bert.) Bertoni (SRB) and stevioside (STV) on glycaemia and gluconeogenesis of 15-h fasted rats. For this purpose, the rats received SRB (20 mg/kg x day), STV (5.5 mg/kg x day) or an equal volume of water (controls) during 15 days. To measure hepatic gluconeogenesis, liver perfusion and isolated hepatocytes were used. Glycaemia and gluconeogenesis from L-alanine (5 mM), L-glutamine (5 mM) and L-lactate (2 mM) were decreased (P < 0.05) after pre-treatment with SRB. However, the treatment with STV did not influence glycaemia and gluconeogenesis. Moreover, to get further information about the mechanism by which SRB leaves inhibit gluconeogenesis their potential role as a PPARgamma agonist was investigated. The data showed absence of activation of PPARgamma receptors. In summary, our results showed that the reduction of glycaemia promoted by the treatment with SRB leaves was mediated, at least in part, by an inhibition of hepatic gluconeogenesis. However, this effect did not involve stevioside and the activation of PPARgamma receptors.