Regulation of Na(+)/H(+) exchanger NHE3 by glucagon-like peptide 1 receptor agonist exendin-4 in renal proximal tubule cells

Carraro-Lacroix LR, Malnic G, Girardi AC. Regulation of Na(+)/H(+) exchanger NHE3 by glucagon-like peptide 1 receptor agonist exendin-4 in renal proximal tubule cells. Am J Physiol Renal Physiol 297: F1647-F1655, 2009. First published September 23, 2009; doi:10.1152/ajprenal.00082.2009.-The gut incretin hormone glucagon-like peptide 1 (GLP-1) is released in response to ingested nutrients and enhances insulin secretion. In addition to its insulinotropic properties, GLP-1 has been shown to have natriuretic actions paralleled by a diminished proton secretion. We therefore studied the role of the GLP-1 receptor agonist exendin-4 in modulating the activity of Na(+)/H(+) exchanger NHE3 in LLC-PK(1) cells. We found that NHE3-mediated Na(+)-dependent intracellular pH (pH(i)) recovery decreased similar to 50% after 30-min treatment with 1 nM exendin-4. Pharmacological inhibitors and cAMP analogs that selectively activate protein kinase A (PKA) or the exchange protein directly activated by cAMP (EPAC) demonstrated that regulation of NHE3 activity by exendin-4 requires activation of both cAMP downstream effectors. This conclusion was based on the following observations: 1) the PKA antagonist H-89 completely prevented the effect of the PKA activator but only partially blocked the exendin-4-induced NHE3 inhibition; 2) the MEK1/2 inhibitor U-0126 abolished the effect of the EPAC activator but only diminished the exendin-4-induced NHE3 inhibition; 3) combination of H-89 and U-0126 fully prevented the effect of exendin-4 on NHE3; 4) no additive effect in the inhibition of NHE3 activity was observed when exendin-4, PKA, and EPAC activators were used together. Mechanistically, the inhibitory effect of exendin-4 on pHi recovery was associated with an increase of NHE3 phosphorylation. Conversely, this inhibition took place without changes in the surface expression of the transporter. We conclude that GLP-1 receptor agonists modulate sodium homeostasis in the kidney, most likely by affecting NHE3 activity.

Study of Blood Porphyrin Spectral Profile for Diagnosis of Chronic Renal Failure

The progression to end-stage renal failure is independent of the initial pathogenic mechanism. Metabolic acidosis is a common consequence of chronic renal failure that results from inadequate ammonium excretion and decreased tubular bicarbonate reabsorption. Protoporphyrin IX (PpIX) is the immediate metabolic precursor of the heme molecule. The purpose of this study was to evaluate the levels of erythrocytes protoporphyrin IX at an animal model during progressive renal disease. A total of 36 eight-week-old male Wistar rats were divided into six groups: Normal, 4 and 8 weeks after 5/6 nephrectomy (NX). Renal function was evaluated by creatinine clearance and plasma creatinine levels. The autofluorescence of erythrocytes porphyrin of healthy and NX rats was analyzed using fluorescence spectroscopy. Emission spectra were obtained by exciting the samples at 405 nm. Significant differences between normal and NX rats autofluorescence shape occurred in the 600-700 nm spectral region. A correlation was observed between emission band intensity at 635 nm and progression of renal disease.

Structural and spectroscopic characterization of poly(styrene sulfonate) films doped with neodymium ions

This work reports the structural and spectroscopy characterization of poly(styrene sulfonate) (PSS) films doped with neodymium (Nd) ions. Nd-PSS films were processed using the acid of poly(styrene sulfonate) - H-PSS and neodymium nitrate - Nd(NO(3))(3); the maximum incorporation of Nd ions in the polymeric matrix was equal 19.3%. The absorption in the UV-Vis-NIR spectral region presents typical electronic transitions of Nd 3, ions, with well resolved peaks. The infrared spectra present the transition bands of PSS with characteristic line shape broadening, and the presence of vibrational modes of N-O groups in the range of 1400-720 cm(-1), prove the permanence of Nd(NO(3))(x), with x = 1, 2 and/or 3. in the H-PSS matrix. UV-Vis site selective photoluminescence data indicate that the incorporation of Nd 31 introduces a blue shift in PSS emission (325-800 nm), decreasing the interaction between adjacent PSS lateral groups (aromatic rings). Nd(3+) reabsorption and energy transfer effects between the PSS matrix and Nd(3+) were also observed. The IR emission of Nd-PSS films at 1076 rim ((4)F(3/2) -> (4)I(11/2)) present constant efficiency, independent on Nd(3+) concentration. The Judd-Ofelt theory was employed to analyze radiative properties. The excitation spectra prove the energy transfer between the polymeric matrix and Nd(3+). Complex impedance data was used to probe relaxation processes during the charge transport within the polymeric matrix. (C) 2008 Elsevier B.V. All rights reserved.

Purification and renal effects of phospholipase A(2) isolated from Bothrops insularis venom

Bothrops insularis venom contains a variety of substances presumably responsible for several pharmacological effects. We investigated the biochemical and biological effects of phospholipase A(2) protein isolated from B. insularis venom and the chromatographic profile showed 7 main fractions and the main phospholipase A(2) (PLA(2)) enzymatic activity was detected in fractions IV and V. Fraction IV was submitted to a new chromatographic procedure on ion exchange chromatography, which allowed the elution of 5 main fractions designated as lV-1 to IV-5, from which lV-4 constituted the main fraction. The molecular homogeneity of this fraction was characterized by high-performance liquid chromatography (HPLC) and demonstrated by mass spectrometry (MS), which showed a molecular mass of 13984.20 Da; its N-terminal sequence presented a high amino acid identity (up to 95%) with the PLA(2) of Bothrops jararaca and Bothrops asper. Phospholipase A(2) isolated from B. insularis (Bi PLA(2)) venom (10 mu g/mL) was also studied as to its effect on the renal function of isolated perfused kidneys of Wistar rats (n = 6). Bi PLA(2) increased perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF) and glomerular filtration rate (GFR). Sodium (%TNa+) and chloride tubular reabsorption (%TCl-) decreased at 120 min, without alteration in potassium transport. In conclusion, PLA(2) isolated from B. insularis venom promoted renal alterations in the isolated perfused rat kidney. (c) 2007 Elsevier Ltd. All rights reserved.

Toxoplasma gondii: Evidence for the transmission by semen in dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Expressão imuno-histoquímica das proteínas IFN-γ e TGF-β1 em cistos radiculares e cistos dentígeros

Odontogenic cysts are pathologic cavities covered by odontogenic epithelium and filled by liquid, desquamated cells or other materials. The intraosseous lesions, such as radicular cyst and dentigerous cyst, present a potential of expansion capable of promoting the destruction of the surrounding osseous tissue. The mechanisms related to this process of expansion are the proliferation of cystic epithelium, the increase of the osmolarity of the cystic fluid and the synthesis of reabsorption factors such as IFN-γ and TGF-β1. The aim of this study was to evaluate and compare the immunohistochemical expression of IFN-γ and TGF-β1 between radicular cysts and dentigerous cysts in order to understand the role and behavior of these proteins in the expansion of these cysts. We selected 20 cases of radicular cyst and 20 cases of dentigerous cyst chosen from the files of UFRN s Laboratory of Oral Pathology. After analyzing the clinical data, the cases underwent the routine staining technique (HE) and immunohistochemistry for the appearance of IFN-γ and TGF-β1 in the epithelium and capsule of these cysts. The statistical analysis using the Mann-Whitney test revealed no statistically significant difference in immunoexpression of IFN-γ between the epithelium (p = 0.565) and capsules (p = 0.414) of radicular cysts and dentigerous cysts. Moreover, there was no statistically significant difference of immunoexpression of TGF-β1 between the epithelium (p = 0.620) and capsules (p = 0.056) of radicular cysts and dentigerous cysts. The Wilcoxon test revealed no statistically significant difference between IFN-γ and TGF-β1 imunoexpressions in the epithelium (p = 0.225) and capsules (p = 0.370) of radicular cysts. There was no statistically significant difference between IFN-γ and TGF-β1 imunoexpressions in the epithelium (p = 0.361) of dentigerous cysts. However, there was a statistically significant difference between IFN-γ and TGF-β1 immunoexpressions in the capsule (p = 0.001) of dentigerous cysts, being TGF-β1 the factor which presented the most significant immunoexpression. Given these results, we conclude that there was no difference in immunohistochemical expression of IFN-γ and TGF-β1 between radicular and dentigerous cysts and that TGF-β1 was more significant than the IFN-γ in the capsule of dentigerous cysts

Efeitos do pneumoperitônio sobre a hemodinâmica e função renais de cães ventilados com volume e pressão controlados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Reversão sexual de rã-touro (Rana catesbeiana) com hormônio masculinizante misturado à ração de girinos

Este trabalho consistiu em testar a eficiência de um hormônio masculinizante (17beta-hidróxi-17-metil-andróxi-4-en-3-ona) na reversão sexual de girinos de rã-touro (Rana catesbeiana). Foram usados 352 girinos com dois a três meses de idade, nos estádios 30 a 36, para testar quatro níveis de hormônio na ração (0, 30, 60 e 90 mig/g) por 45 dias. Após a metamorfose, 167 imagos foram sacrificados e 185 imagos foram criados até a idade de quatro meses e, então, sacrificados. As análises macroscópicas das gônadas e das características sexuais secundárias confirmaram a masculinização nos tratamentos com hormônio. Muitos ovócitos foram observados nos testículos dos imagos revertidos (ovotestis); entretanto, quatro meses após a metamorfose, os ovotestis ocorreram esporadicamente. Concluiu-se que, após a metamorfose, iniciou-se um processo de reabsorção dos ovócitos nos imagos revertidos, culminando com a quase total reabsorção dos ovócitos no quarto mês de idade.

Use of radiograph optical densitometry to monitor bone quality in broiler breeders

This study was carried out at Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista, Botucatu, SP, Brazil, and evaluated bone quality in broiler breeders. Twenty-three families of Ross broiler breeders were housed in 5.0-m² pens. The families were comprised of 13 females and one male at the onset of the experimental period. The mean number of females per family was 9.34 at the end of the trial. The feeding program and management followed strain guidelines (Agroceres Ross, 2003). Bone analyses were performed in the right tibia and femur using optical radiographic densitometry at 4, 8, 12, 15, 20, 24, 30, 35, 42, 47 and 52 weeks of rearing. Trap nests were used to collect eggs from the breeders two weeks before and after the evaluation weeks. At each evaluation day, five birds were sacrificed after radiographs were taken and the tibias and femurs were collected to perform the following analyses: fatfree dry matter, ash percentage, bone resistance and Seedor index. Therefore, it was possible to establish correlations between bone quality and eggshell quality. Characteristics of bone quality were highly correlated to each other; on the other hand, there were no correlations between bone quality and external egg quality. In conclusion, there was no effect of egg production on egg quality, possibly because there was no reabsorption of bone minerals.

Maternal undernutrition and the offspring kidney: from fetal to adult life

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Electrophoretical polypeptide pattern of hypopharyngeal glands extracts from workers and males of Scaptotrigona postica Latr. (Hymenoptera, Apidae, Meliponinae)

In S. postica the hypopharyngeal glands are present in workers, males and queens. The glands of newly emerged workers are in a prefunctional phase, in nurse workers they reach their highest development and in forager workers they suffer reabsorption. The newly emerged males and queens, however, have well developed glands that soon start involution. The electrophoretical pattern of worker and male hypopharyngeal glands is compared with the pattern of nurse workers of A. mellifera. The results show simularities, as well as differences among the S. postica males and workers, and among the phases of worker life. The electrophoretic band pattern suggests that the hypopharyngeal glands of nurse workers of S. postica produce substances similar to the ones produced by A. mellifera. The similarity of the extracts of nurse glands of A. mellifera and S. postica, as well as the behavioural similarities of the workers, suggest the same function of this gland in both species.

Morphological, histological, and ultrastructural studies of the ovary of the cattle-tick Boophilus microplus (Canestrini, 1887) (Acari : Ixodidae)

This study presents the morphology of the ovary, as well as the dynamics of the vitellogenesis process in oocytes of the cattle-tick Boophilus microplus. The ovary of these individuals is of the panoistic type; therefore, it lacks nurse cells. This organ consists of a single tubular structure, continuous, and composed of a lumen delimitated by a wall of small epithelial cells with rounded nuclei. In this tick species, the oocytes were classified into six stages varying from I to VI and according to: cytoplasm appearance and presence of the germ vesicle, yolk granules, and chorion. Oocytes of various sizes and at different developmental stages remain attached to the ovary through a cellular pedicel until completing stage V. Afterwards, they are liberated into the lumen and from there to the exterior. Some oocytes (classified as type VI) showed an atypical appearance indicating that some of the cellular components would be undergoing a degenerative process and/or reabsorption. (c) 2004 Elsevier B.V. All rights reserved.

Comparative study of the ultrastructure and secretory dynamic of hypopharyngeal glands in queens, workers and males of Sceptotrigona postica latreille (Hymenoptera, Apinae, Meliponini)

The secretory cycle of hypopharyngeal glands (HPGs) in Scaptotrigona postica resembles that of Apis mellifera: in newly emerged workers the HPGs are in prefunctional state, their maximum development happens in the nurse workers and in forager workers they show signs of reabsorption. In S. postica these glands are also present in queens and males where they are more developed in newly emerged individuals. The ultrastructural features of the HPG secretory cycle in workers of S. postica and A. mellifera are alike: granular endoplasmic reticulum well developed, large secretion masses around the intracellular canaliculus in nurse workers and extensive degenerative structures in forager workers. Then it is suggested that the HPG secrete similar substances in both species. A second secretory cycle seems to occur in early foragers, may be with production of enzymes. The role of the HPGs in queens and males remains unknown but one possibility is enzyme production.

Morphological characterization of cell death during the ovary differentiation in worker honey bee

Cell death that occurs during ovary differentiation in the honeybee worker's larval development accounts for ovariole reabsorption. From a morphological standpoint, three modes of death were detected. Germinative cells in the ovarioles die by an apoptotic-like process, whereas the somatic cells die by an autophagic process, type 11 cell death; and during pupation, stromatic and ovarian capsular cells die through cytoplasmic disintegration, releasing their components into the hemolymph. These modes of cell death are in part determined by the pattern of tissue organization within which the cell occurs. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Morphological records of oocyte maturation in the parthenogenetic tick Amblyomma rotundatum Koch, 1844 (Acari: Ixodidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)