Excess mortality associated with COVID-19 in Brazil: 2020-2021.

OBJECTIVE: To evaluate excess mortality in Brazil from January 2020 to April 2021, according to the primary causes of death registered in the Brazilian Mortality Information System (MIS). METHODS: Cross-sectional study with data extracted from the MIS. Excess deaths were examined by the primary cause of death according to 11 grouped causes. Autoregressive models used mortality data from 2015 to 2019 to predict expected deaths from January 2020 to April 2021. Excess deaths were calculated as the difference between the observed and the expected number of deaths. RESULTS: Total excess deaths of 370 055 were observed in the studied period, corresponding to a ratio of observed to expected of 1.14 in 2020 and 1.40 in 2021. Excess deaths were seen in three groups: symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified; other diseases of the respiratory system and coronavirus infection, unspecified site. CONCLUSIONS: The excess mortality in Brazil in these 16 months was 1.20 times greater than the previous year. The increase in not elsewhere classified causes and causes of death associated to COVID-19 indicate caution about the negative balance for some causes. Furthermore, the inequalities of mortality reporting systems in low- and middle-income countries in relation to underestimation of mortality still need to be addressed.

Tropical forages: morphoanatomy of plants grown in areas with the death of pasture syndrome / Forrageiras tropicais: anatomia e morfometria de plantas cultivadas em áreas com síndrome da morte de pastagens

Abstract Roots and leaves of Panicum maximum Tanzânia, Mombaça and Massai; Urochloa brizantha Piatã, Marandu and Xaraés; Urochloa humidicola Llanero; Urochloa ruziziensis Ruzizienses; Urochloa hybrida Mulato II and Cynodon nlemfuensis Estrela-roxa were analyzed, seeking to identify characters for better adaptation to the environment that may interfere with digestibility of tissue from the point of view of the rumen in cattle. Were planted ten cultivars in a completely randomized blocks with three repetitions. Was collected vegetative material, which histological slides were prepared from middle third of the sections of roots and leaves. Were observed differences (p>0.05) in the roots: higher volume of epidermal cells (28.62 µm) and overall diameter (1926.41 µm) of Llanero; thicker vascular cylinder (975.09 µm) and more protoxylem (42.25) in Estrela-roxa and occurrence of aerenchyma in cultivars Piatã, Mulato II, Xaraés, Massai, Llanero and Estrela-roxa; Were found higher proportions of bulliform cells in the leaves (121.07 µm) and thicker leaf mesophyll in U. humidicola Llanero (263.63 µm); higher proportion of sclerenchyma fibers in Xaraés and Marandu; lower results for amount of fibers in P. maximum Massai. We conclude that the cultivars Estrela-roxa, Llanero and Massai have greater adaptability to the environment and better nutritional quality.

Resumo Foram analisadas raízes e folhas de Panicum maximum Tanzânia, Mombaça e Massai; Urochloa brizantha Piatã, Marandu e Xaraés; Urochloa humidicola Llanero; Urochloa ruziziensis Ruzizienses; Urochloa hybrida Mulato II e Cynodon nlemfuensis Estrela-roxa, procurando identificar caracteres relacionados à melhor adaptação ao ambiente e à qualidade nutritiva das forrageiras. As dez cultivares foram semeadas em blocos inteiramente casualizados com três repetições. Após estabelecidas foi coletado material vegetativo, do qual lâminas histológicas foram confeccionadas a partir de secções do terço médio de raízes e folhas. Foram observadas diferenças significativas (p>0,05) nas raízes: maior volume de células epidérmicas (28,62 µm) e diâmetro total (1926,41 µm) de Llanero; em Estrela-roxa maior espessura do cilindro vascular (975,09 µm) e número maior de protoxilemas (42,25) e formação de aerênquimas nas cultivares Piatã, Mulato II, Xaraés, Massai, Llanero, e Estrela-roxa; Nas folhas, foram constatadas maiores proporções de células buliformes (121,07 µm) e mesofilo foliar mais espesso (263,63 µm) em Llanero; em Xaraés e Marandu maiores proporções de fibras esclerenquimáticas; em Massai menores resultados para quantidade de fibras. Conclui-se que as cultivares Estrela-roxa, Llanero e Massai apresentam maior adaptabilidade ao ambiente e melhor qualidade nutritiva.

Role of aquaporin-7 in ghrelin- and GLP-1-induced improvement of pancreatic ß-cell function after sleeve gastrectomy in obese rats.

BACKGROUND/OBJECTIVES: Glycerol is a key metabolite for lipid accumulation in insulin-sensitive tissues as well as for pancreatic insulin secretion. We examined the role of aquaporin-7 (AQP7), the main glycerol channel in ß-cells, and AQP12, an aquaporin related to pancreatic damage, in the improvement of pancreatic function and steatosis after sleeve gastrectomy in diet-induced obese rats. SUBJECTS/METHODS: Male Wistar obese rats (n=125) were subjected to surgical (sham operation and sleeve gastrectomy) or dietary (pair-fed to the amount of food eaten by sleeve-gastrectomized animals) interventions. The tissue distribution and expression of AQPs in the rat pancreas were analyzed by real-time PCR, western blotting and immunohistochemistry. The effect of ghrelin isoforms and glucagon-like peptide 1 (GLP-1) on insulin secretion, triacylglycerol (TG) accumulation and AQP expression was determined in vitro in RIN-m5F ß-cells. RESULTS: Sleeve gastrectomy reduced pancreatic ß-cell apoptosis, steatosis and insulin secretion. Lower ghrelin and higher GLP-1 concentrations were also found after bariatric surgery. Acylated and desacyl ghrelin increased TG content, whereas GLP-1 increased insulin release in RIN-m5F ß-cells. Sleeve gastrectomy was associated with an upregulation of AQP7 together with a normalization of the increased AQP12 levels in the rat pancreas. Interestingly, ghrelin and GLP-1 repressed AQP7 and AQP12 expression in RIN-m5F ß-cells. AQP7 protein was negatively correlated with intracellular lipid accumulation in acylated ghrelin-treated cells and with insulin release in GLP-1-stimulated ß-cells. CONCLUSIONS: AQP7 upregulation in ß-cells after sleeve gastrectomy contributes, in part, to the improvement of pancreatic steatosis and insulin secretion by increasing intracellular glycerol used for insulin release triggered by GLP-1 rather than for ghrelin-induced TG biosynthesis.

Tropical forages: morphoanatomy of plants grown in areas with the death of pasture syndrome.

Roots and leaves of Panicum maximum Tanzânia, Mombaça and Massai; Urochloa brizantha Piatã, Marandu and Xaraés; Urochloa humidicola Llanero; Urochloa ruziziensis Ruzizienses; Urochloa hybrida Mulato II and Cynodon nlemfuensis Estrela-roxa were analyzed, seeking to identify characters for better adaptation to the environment that may interfere with digestibility of tissue from the point of view of the rumen in cattle. Were planted ten cultivars in a completely randomized blocks with three repetitions. Was collected vegetative material, which histological slides were prepared from middle third of the sections of roots and leaves. Were observed differences (p>0.05) in the roots: higher volume of epidermal cells (28.62 µm) and overall diameter (1926.41 µm) of Llanero; thicker vascular cylinder (975.09 µm) and more protoxylem (42.25) in Estrela-roxa and occurrence of aerenchyma in cultivars Piatã, Mulato II, Xaraés, Massai, Llanero and Estrela-roxa; Were found higher proportions of bulliform cells in the leaves (121.07 µm) and thicker leaf mesophyll in U. humidicola Llanero (263.63 µm); higher proportion of sclerenchyma fibers in Xaraés and Marandu; lower results for amount of fibers in P. maximum Massai. We conclude that the cultivars Estrela-roxa, Llanero and Massai have greater adaptability to the environment and better nutritional quality.

Death of pastures syndrome: tissue changes in Urochloa hybrida cv. Mulato II and Urochloa brizantha cv. Marandu / Síndrome da morte das pastagens: Alterações teciduais em Urochloa hybrida cv. Mulato II e Urochloa brizantha cv. Marandu

Abstract The quality of forage production is a prerequisite to raising livestock. Therefore, income losses in this activity, primarily cattle raising, can result in the impossibility of economic activity. Through the qualitative and quantitative anatomical study of Urochloa hybrida cv. Mulato II and U. brizantha cv. Marandu, we searched for descriptions and compared changes in the individual vegetative body from populations with death syndrome pastures (DPS). Specimens were collected at different physiological stages from farms in northern Mato Grosso. After collection, the individuals were fixed in FAA50 and stored in 70% alcohol. Histological slides were prepared from the middle third of the sections of roots, rhizomes, and leaves, and the proportions and characteristics of tissues were evaluated in healthy, intermediate, and advanced stages of DPS. Changes were compared between cultivars. With the advancement of the syndrome, the following changes were observed: a more marked decrease in the length of roots in U. hybrida; disorganization of the cortical region of the roots and rhizome cultivars; fungal hyphae in roots and aerenchyma formation in U. hybrida; a decrease in sclerenchyma fiber proportions in roots and leaves; sclerification of the epidermis of U. brizantha rhizomes; and an increase in pericyclic fibers in U. hybrida. Furthermore, there was a decrease in the volume of epidermal cells of the abaxial face of the leaves of both cultivars, with a greater reduction in U. hybrida; a gradual decrease in thickness in the midrib of leaves similar to leaf mesophyll; conduction system obstructions; partial or total cell lysis in roots and rhizomes affected by the syndrome. Obstructions in sieve tube element and companion cells, and sometimes obstruction in xylem vessel elements. The evolution of DPS in cultivars was similar, but there were variations, arising probably from the physiological response to stress, such as aerenchyma formation in the root and increased pericycle in the rhizome of U. hybrida.

Resumo A produção de forragem de qualidade é um pressuposto indispensável à atividade pecuária moderna. Dessa forma, perdas de rendimento nesta atividade preliminar à criação bovina, podem inviabilizar esta atividade econômica. Através de estudos anatômicos qualitativos e quantitativos em Urochloa hybrida cv. Mulato II e U. brizantha cv. Marandu buscou-se descrever e comparar as alterações do corpo vegetativo de indivíduos de populações que apresentam síndrome da morte das pastagens (SMP). Foram coletados indivíduos em estádios morfológicos distintos em propriedades rurais no norte de Mato Grosso, Amazônia Meridional. Após a coleta, os indivíduos foram fixados em FAA50 e armazenados em álcool 70%. Lâminas histológicas foram confeccionadas a partir de secções do terço médio de raízes, rizomas e folhas, onde foram avaliadas as características e proporções dos tecidos em indivíduos saudáveis, indivíduos em estádio intermediário e também em estádio mais avançado da SMP, bem como comparadas as alterações entre as duas cultivares. Com o avanço da síndrome verificou-se diminuição mais acentuada da extensão de raízes em U. hybrida. A região cortical das raízes e do rizoma das cultivares exibiu desorganização, sendo observada nas raízes a presença de hifas fúngicas e a formação de aerênquima em U. hybrida. As proporções de fibras esclerenquimáticas diminuíram nas raízes e folhas. No rizoma, a epiderme de U. brizantha apresentou esclerificação e U. hybrida exibiu aumento da quantidade de fibras pericíclicas. Houve diminuição do volume das células epidérmicas da face abaxial das folhas de ambas as cultivares, com maior diminuição em U. hybrida. A região da nervura central das folhas apresentou gradativa diminuição com espessura similar ao mesofilo foliar. O sistema de condução apresentou obstruções, onde elementos de tubo crivado e células companheiras do floema das raízes e rizomas afetados pela síndrome exibiram parcial ou total lise celular e os elementos de vaso do xilema por vezes se mostraram obstruídos. A evolução da SMP nas cultivares estudadas é semelhante, contudo houve variações decorrentes provavelmente da resposta fisiológica ao estresse, como a formação de aerênquima na raiz, alteração e aumento da espessura do periciclo do rizoma de U. hybrida.

Anatomy and micromorphometric analysis of leaf Catasetum x apolloi Benelli & Grade with addition of potassium silicate under different light sources / Anatomia e análise micromorfométrica foliar de Catasetum x apolloi Benelli & Grade com adição de silicato de potássio em diferentes fontes de luz

Abstract The aim of this study was to compare vitroplants Catasetum x apolloi grown under natural light and artificial light and different concentrations of potassium silicate, providing data on the anatomical differentiation that aids the acclimatization process of this species. Plants from in vitro seeding were used; 5 protocorms of approximately 0.5 cm were inoculated into vials with a capacity of 500 mL containing 100 mL of alternative culture medium plus potassium silicate (0.0, 0.5; 1.0 mL L–1), pH adjusted to 5.5 ± 0.5 and gelated with 4GL–1 agar before the autoclaving process. Cultures were maintained under natural light (TNE) and artificial light (TAE) for 90 days, and micromorphometric analysis was performed for polar and equatorial diameter, density and stomatal index, blade thickness in the central rib, and secondary veins. Applications in K2SiO4 alternative medium provided the following: elongation of the hypodermis, thicker mesophyll, and more prominent midrib; elipptical guard cells; formation of epistomatal chamber; and lower stomatal density and stomatal with lower equatorial and polar diameters. The conditions that favored the acclimatization were lower light intensities and lower potassium silicate doses.

Resumo O objetivo desse trabalho foi comparar vitroplantas de Catasetum x apolloi cultivadas sob luz natural e luz artificial e diferentes concentrações de silicato de potássio, fornecendo dados sobre diferenciação anatômica que auxiliem no processo de aclimatação dessa espécie. Utilizou-se plantas provenientes da semeadura in vitro, 5 protocormos de aproximadamente 0,5 cm foram inoculados em frascos com capacidade para 500 mL contendo 100 mL de meio de cultura alternativo, acrescido de silicato de potássio (0,0; 0,5; 1,0 mL L–1), pH ajustado para 5,5 ±0,5 e gelificado com 4gL–1 de ágar antes do processo de autoclavagem. As culturas foram mantidas sob luz natural (TAA) e luz artificial (TAN) por 90 dias, e feitas análises micromorfométricas (diâmetro polar e equatorial, densidade e índice estomático, espessura do limbo na nervura central e nervuras secundárias). As aplicações de K2SiO4 em meio alternativo, propiciaram: alongamento da hipoderme; mesofilo mais espesso e nervura central mais proeminente; células guardas elípticas; formação de câmaras supraestomáticas; menor densidade estomática e estômatos com menores diâmetros equatorial e polar. As condições que podem favorecer a aclimatação são menores intensidades de luz e menores doses de silicato de potássio.

Anatomy and micromorphometric analysis of leaf Catasetum x apolloi Benelli & Grade with addition of potassium silicate under different light sources.

The aim of this study was to compare vitroplants Catasetum x apolloi grown under natural light and artificial light and different concentrations of potassium silicate, providing data on the anatomical differentiation that aids the acclimatization process of this species. Plants from in vitro seeding were used; 5 protocorms of approximately 0.5 cm were inoculated into vials with a capacity of 500 mL containing 100 mL of alternative culture medium plus potassium silicate (0.0, 0.5; 1.0 mL L-1), pH adjusted to 5.5 ± 0.5 and gelated with 4GL-1 agar before the autoclaving process. Cultures were maintained under natural light (TNE) and artificial light (TAE) for 90 days, and micromorphometric analysis was performed for polar and equatorial diameter, density and stomatal index, blade thickness in the central rib, and secondary veins. Applications in K2SiO4 alternative medium provided the following: elongation of the hypodermis, thicker mesophyll, and more prominent midrib; elipptical guard cells; formation of epistomatal chamber; and lower stomatal density and stomatal with lower equatorial and polar diameters. The conditions that favored the acclimatization were lower light intensities and lower potassium silicate doses.

Death of pastures syndrome: tissue changes in Urochloa hybrida cv. Mulato II and Urochloa brizantha cv. Marandu.

The quality of forage production is a prerequisite to raising livestock. Therefore, income losses in this activity, primarily cattle raising, can result in the impossibility of economic activity. Through the qualitative and quantitative anatomical study of Urochloa hybrida cv. Mulato II and U. brizantha cv. Marandu, we searched for descriptions and compared changes in the individual vegetative body from populations with death syndrome pastures (DPS). Specimens were collected at different physiological stages from farms in northern Mato Grosso. After collection, the individuals were fixed in FAA50 and stored in 70% alcohol. Histological slides were prepared from the middle third of the sections of roots, rhizomes, and leaves, and the proportions and characteristics of tissues were evaluated in healthy, intermediate, and advanced stages of DPS. Changes were compared between cultivars. With the advancement of the syndrome, the following changes were observed: a more marked decrease in the length of roots in U. hybrida; disorganization of the cortical region of the roots and rhizome cultivars; fungal hyphae in roots and aerenchyma formation in U. hybrida; a decrease in sclerenchyma fiber proportions in roots and leaves; sclerification of the epidermis of U. brizantha rhizomes; and an increase in pericyclic fibers in U. hybrida. Furthermore, there was a decrease in the volume of epidermal cells of the abaxial face of the leaves of both cultivars, with a greater reduction in U. hybrida; a gradual decrease in thickness in the midrib of leaves similar to leaf mesophyll; conduction system obstructions; partial or total cell lysis in roots and rhizomes affected by the syndrome. Obstructions in sieve tube element and companion cells, and sometimes obstruction in xylem vessel elements. The evolution of DPS in cultivars was similar, but there were variations, arising probably from the physiological response to stress, such as aerenchyma formation in the root and increased pericycle in the rhizome of U. hybrida.

Genetic structure of natural populations of Theobroma in the Juruena National Park, Mato Grosso State, Brazil.

Several species within the genus Theobroma have particularly high economic value, including T. cacao and T. grandiflorum. Other species in this genus, such as T. speciosum and T. subincanum, have potential value for use in the conservation of genetic diversity in breeding programs. These latter species could also be domesticated or improved to produce commercial products. Using 13 simple sequence repeat loci, the population structure and genetic diversity of T. speciosum and T. subincanum natural populations in the Juruena National Park, Mato Grosso State, Brazil, was studied. We sampled all individuals of each species (N = 25) present inside a designated research area established by the Program for Research on Biodiversity. The average number of alleles per locus was 5 for T. speciosum and 6.69 for T. subincanum, with average PIC values above 0.5 in both species. All evaluated individuals varied genetically. Seeds from the individuals analyzed will be useful for the development of germplasm banks and for establishment of breeding programs.

Pacientes adultos com leucemia aguda - experiência da Faculdade de Medicina do ABC / Adult patients with acute leukemia - ABC Medical School experience

Introdução: Houve uma melhora lenta, porém definitiva no tratamento das leucemias agudas nos últimos anos. No entanto, existem controvérsias para pacientes com características específicas. Este trabalho tem como objetivo descrever o perfil epidemiológico dos pacientes com leucemia aguda atendidos no Hospital Estadual Mário Covas (HEMC), assim como demonstrar as curvas de sobrevida global e livre de doença e as taxas de mortalidade desta população. Métodos: Realizado estudo de corte transversal para avaliação de pacientes com diagnóstico de leucemias agudas da FMABC atendidos, no HEMC, no período de 2008 a 2012. Análise estatística das curvas de sobrevida utilizando Kaplan-Meier (XL Stat® v2012). Resultados: LMA: 50 pacientes com média de 57,72 anos de idade (18 a 89 anos), predomínio do sexo feminino 2,12: 1 e SLD = SG = 42 meses (média de seguimento = 49,9 meses); sendo 12 pacientes com LMA-M3 (SG=SLD=50%) e 38 outros subtipos (SG=SLD=39,5%). LLA: 17 pacientes, com média de 33,7 anos de idade (19 a 66 anos), predomínio do sexo masculino 1,43: 1 e SG = 58,82%, SLD = 47,3% (média de seguimento = 24,6 meses). Conclusão: Pacientes com LMA que atingem resposta na fase de indução apresentam curvas de SG e SLD compatíveis com a literatura. Pacientes com LLA apresentam SG e SLD inferior ao observado na literatura. É preciso prosseguir com este programa a fim de determinar o melhor tratamento para estes pacientes e o impacto do TCTH, assim como sua viabilidade.

Na+-dependent and Na+-independent mechanisms for inorganic phosphate uptake in Trypanosoma rangeli.

BACKGROUND: Trypanosoma rangeli is dependent on the presence of exogenous orthophosphate (Pi) for maximal growth and ecto-phosphatase activity is responsible for Pi supply under low Pi. Here we investigated the mechanisms of Pi uptake. METHODS: We investigated the kinetics of 32Pi transport, its Na+ and H+ dependence, its correlation with the Na+-ATPase and H+-ATPase, and gene expression of the Na+:Pi cotransporter and Na+-ATPase. RESULTS: T. rangeli grown under limiting Pi transports this anion to the cytosol in the absence and presence of Na+, suggesting that influx is mediated by both Na+-independent and Na+-dependent transporters. Cloning studies demonstrated that this parasite expresses a Pi transporter not previously studied in trypanosomatids. The H+ ionophore, carbonylcyanide-p-trifluoromethoxyphenylhydrazone, decreased both components of 32Pi influx by 80-95%. The H+-ATPase inhibitor, bafilomycin A1, inhibited the Na+-independent mechanism. Furosemide, an inhibitor of ouabain-insensitive Na+-ATPase, decreased both uptake mechanisms of 32Pi to the same extent, whereas ouabain had no effect, indicating that the former is the pump responsible for inwardly directed Na+ and the electric gradients required by the transporters. Parasite growth in high Pi had a lower Pi influx than that found in those grown in low Pi, without alteration in TrPho89 expression, showing that turnover of the transporters is stimulated by Pi starvation. CONCLUSIONS: Two modes of Pi transport, one coupled to Na+-ATPase and other coupled to H+-ATPase seem to be responsible for Pi acquisition during development of T. rangeli. GENERAL SIGNIFICANCE: This study provides the first description of the mechanism of Pi transport across the plasma membrane of trypanosomatids.

Gender-dependent effects of aging on the kidney.

It is well known that the kidney plays an important role in the development of cardiovascular diseases such as hypertension. The normal aging process leads to changes in kidney morphology, hemodynamics and function, which increase the incidence of cardiovascular events in the elderly population. These disturbances are influenced by several factors, including gender. In general, females are protected by the effects of estrogens on the cardiorenal system. Several studies have demonstrated the beneficial effects of estrogens on renal function in the elderly; however, the relationships between androgens and kidney health during one's lifetime are not well understood. Sex steroids have many complex actions, and the decline in their levels during aging clearly influences kidney function, decreases the renal reserve and facilitates the development of cardiovascular disorders. Therefore, in this review, we discuss the cellular, biochemical, and molecular mechanisms by which sex hormones may influence renal function during the aging process.

Gender-dependent effects of aging on the kidney

It is well known that the kidney plays an important role in the development of cardiovascular diseases such as hypertension. The normal aging process leads to changes in kidney morphology, hemodynamics and function, which increase the incidence of cardiovascular events in the elderly population. These disturbances are influenced by several factors, including gender. In general, females are protected by the effects of estrogens on the cardiorenal system. Several studies have demonstrated the beneficial effects of estrogens on renal function in the elderly; however, the relationships between androgens and kidney health during one’s lifetime are not well understood. Sex steroids have many complex actions, and the decline in their levels during aging clearly influences kidney function, decreases the renal reserve and facilitates the development of cardiovascular disorders. Therefore, in this review, we discuss the cellular, biochemical, and molecular mechanisms by which sex hormones may influence renal function during the aging process.

Endogenous angiotensin II modulates nNOS expression in renovascular hypertension.

Nitric oxide (NO) influences renal blood flow mainly as a result of neuronal nitric oxide synthase (nNOS). Nevertheless, it is unclear how nNOS expression is modulated by endogenous angiotensin II, an inhibitor of NO function. We tested the hypothesis that the angiotensin II AT1 receptor and oxidative stress mediated by NADPH oxidase contribute to the modulation of renal nNOS expression in two-kidney, one-clip (2K1C) hypertensive rats. Experiments were performed on male Wistar rats (150 to 170 g body weight) divided into 2K1C (N = 19) and sham-operated (N = 19) groups. nNOS expression in kidneys of 2K1C hypertensive rats (N = 9) was compared by Western blotting to that of 2K1C rats treated with low doses of the AT1 antagonist losartan [10 mg x kg(-1) x day(-1); N = 5] or the superoxide scavenger tempol [0.2 mmol x kg(-1) x day(-1); N = 5], which still remain hypertensive. After 28 days, nNOS expression was significantly increased by 1.7-fold in the clipped kidneys of 2K1C rats and by 3-fold in the non-clipped kidneys of 2K1C rats compared with sham rats, but was normalized by losartan. With tempol treatment, nNOS expression increased 2-fold in the clipped kidneys and 1.4-fold in the non-clipped kidneys compared with sham rats. The changes in nNOS expression were not followed by changes in the enzyme activity, as measured indirectly by the cGMP method. In conclusion, AT1 receptors and oxidative stress seem to be primary stimuli for increased nNOS expression, but this up-regulation does not result in higher enzyme activity.

Endogenous angiotensin II modulates nNOS expression in renovascular hypertension

Nitric oxide (NO) influences renal blood flow mainly as a result of neuronal nitric oxide synthase (nNOS). Nevertheless, it is unclear how nNOS expression is modulated by endogenous angiotensin II, an inhibitor of NO function. We tested the hypothesis that the angiotensin II AT1 receptor and oxidative stress mediated by NADPH oxidase contribute to the modulation of renal nNOS expression in two-kidney, one-clip (2K1C) hypertensive rats. Experiments were performed on male Wistar rats (150 to 170 g body weight) divided into 2K1C (N = 19) and sham-operated (N = 19) groups. nNOS expression in kidneys of 2K1C hypertensive rats (N = 9) was compared by Western blotting to that of 2K1C rats treated with low doses of the AT1 antagonist losartan (10 mg·kg-1·day-1; N = 5) or the superoxide scavenger tempol (0.2 mmol·kg-1·day-1; N = 5), which still remain hypertensive. After 28 days, nNOS expression was significantly increased by 1.7-fold in the clipped kidneys of 2K1C rats and by 3-fold in the non-clipped kidneys of 2K1C rats compared with sham rats, but was normalized by losartan. With tempol treatment, nNOS expression increased 2-fold in the clipped kidneys and 1.4-fold in the non-clipped kidneys compared with sham rats. The changes in nNOS expression were not followed by changes in the enzyme activity, as measured indirectly by the cGMP method. In conclusion, AT1 receptors and oxidative stress seem to be primary stimuli for increased nNOS expression, but this up-regulation does not result in higher enzyme activity.

PI-PLCbeta is involved in the modulation of the proximal tubule Na+-ATPase by angiotensin II.

In previous papers we showed that Ang II increases the proximal tubule Na+-ATPase activity through AT1/PKC pathway [L.B. Rangel, C. Caruso-Neves, L.S. Lara, A.G. Lopes, Angiotensin II stimulates renal proximal tubule Na+-ATPase activity through the activation of protein kinase C. Biochim. Biophys. Acta 1564 (2002) 310-316, L.B.A. Rangel, A.G. Lopes, L.S. Lara, C. Caruso-Neves, Angiotensin II stimulates renal proximal tubule Na+)-ATPase activity through the activation of protein kinase C. Biochim. Biophys. Acta 1564 (2002) 310-316]. In the present paper, we study the involvement of PI-PLCbeta on the stimulatory effect of angiotensin II (Ang II) on the proximal tubule Na+-ATPase activity. Western blotting assays, using a polyclonal antibody for PI-PLCbeta, show a single band of about 150 KDa, which correspond to PI-PLCbeta isoforms. Ang II induces a rapid decrease in PIP2 levels, a PI-PLCbeta substrate, being the maximal effect observed after 30 s incubation. This effect of Ang II is completely abolished by 5 x 10(-8) M U73122, a specific inhibitor of PI-PLCbeta. In this way, the effect of 10(-8) M Ang II on the proximal tubule basolateral membrane (BLM) Na+-ATPase activity is completely abolished by 5 x 10(-8) M U73122. The increase in diacylglycerol (DAG) concentration, an product of PI-PLCbeta, from 0.1 to 10 nM raises the Na+-ATPase activity from 6.1+/-0.2 to 13.1+/-1.8 nmol Pi mg(-1) min(-1). This effect is similar and non-additive to that observed with Ang II. Furthermore, the stimulatory effect of 10 nM DAG is completely reversed by 10(-8) M calphostin C (Calph C), an inhibitor of PKC. Taken together these data indicate that Ang II stimulates the Na+-ATPase activity of proximal tubule BLM through a PI-PLCbeta/PKC pathway.

Cytoskeleton elements mediate the inhibition of the (Na++K+)atpase activity by PKC in Rhodnius prolixus malpighian tubules during hyperosmotic shock.

In a previous paper, we observed that the specific activity of (Na++K+)ATPase of the isolated Malpighian tubules from Rhodnius prolixus is inhibited by protein kinase C (PKC) during hyperosmotic shock [Arenstein et al., J Membr Biol 146:47-57 [1995]; Caruso-Neves et al., Z Naturforsch 53c:911-917 [1998]). In the present paper, we study the involvement of the cytoskeleton in this process using isolated Malpighian tubules of Rhodnius prolixus. We observed that pre-incubation of the Malpighian tubule cells in hyperosmotic media decreases the specific activity of (Na++K+)ATPase by 90%. This effect was completely reversed when colchicine, which disrupts microtubules, or cytochalasin B, an inhibitor of actin microfilament polymerization, were added to the media in a dose-dependent manner. The maximal reversion was obtained with colchicine 7.0 microM or cytochalasin B 5.0 microM. The simultaneous addition of sphingosine 50 ng/mL, an inhibitor of PKC, to 10 microM colchicine or 5 microM cytochalasin B, in hyperosmotic media, did not change the stimulatory effect of these drugs on the specific activity of (Na++K+)ATPase. On the other hand, the co-incubation of TPA 20 ng/mL, an activator of PKC, to colchicine or cytochalasin B within hyperosmotic media, abolished the stimulatory effect of these drugs on the specific activity of (Na++K+)ATPase to a similar extent as hyperosmotic shock. These results suggest that inhibition of the (Na++K+)ATPase of the isolated Malpighian tubules from Rhodnius prolixus by PKC during hyperosmotic shock is mediated by cytoskeletal elements.

Protein kinase C-induced phosphorylation modulates the Na(+)-ATPase activity from proximal tubules.

This study describes the modulation of the ouabain-insensitive Na(+)-ATPase activity from renal proximal tubule basolateral membranes (BLM) by protein kinase C (PKC). Two PKC isoforms were identified in BLM, one of 75 kDa and the other of 135 kDa. The former correlates with the PKC isoforms described in the literature but the latter seems to be a novel isoform, not yet identified. Both PKC isoforms of BLM are functional since a protein kinase C activator, TPA, increased the total hydroxylamine-resistant 32P(i) incorporation from [gamma-32P]ATP into the BLM. In parallel, TPA stimulated the Na(+)-ATPase activity from BLM in a dose-dependent manner, the effect being reversed by the PKC inhibitor sphingosine. The stimulatory effect of TPA on Na(+)-ATPase involved an increase in the V(max) (from 13.4+/-0.6 nmol P(i) mg(-1) min(-1) to 25.2+/-1.4 nmol P(i) mg(-1) min(-1), in the presence of TPA, P<0.05) but did not change the apparent affinity for Na(+) (K(0.5)=14.5+/-2.1 mM in control and 10.0+/-2.1 mM in the presence of TPA, P>0.07). PKC involvement was further confirmed by stimulation of the Na(+)-ATPase activity by the catalytic subunit of PKC (PKC-M). Finally, the phosphorylation of an approx. 100 kDa protein in the BLM (the suggested molecular mass of Na(+)-ATPase [1]) was induced by TPA. Taken together, these findings indicate that PKCs resident in BLM stimulate Na(+)-ATPase activity which could represent an important mechanism of regulation of proximal tubule Na(+) reabsorption.

ClC-5 chloride channel and kidney stones: what is the link?

Nephrolithiasis is one of the most common diseases in the Western world. The disease manifests itself with intensive pain, sporadic infections, and, sometimes, renal failure. The symptoms are due to the appearance of urinary stones (calculi) which are formed mainly by calcium salts. These calcium salts precipitate in the renal papillae and/or within the collecting ducts. Inherited forms of nephrolithiasis related to chromosome X (X-linked hypercalciuric nephrolithiasis or XLN) have been recently described. Hypercalciuria, nephrocalcinosis, and male predominance are the major characteristics of these diseases. The gene responsible for the XLN forms of kidney stones was cloned and characterized as a chloride channel called ClC-5. The ClC-5 chloride channel belongs to a superfamily of voltage-gated chloride channels, whose physiological roles are not completely understood. The objective of the present review is to identify recent advances in the molecular pathology of nephrolithiasis, with emphasis on XLN. We also try to establish a link between a chloride channel like ClC-5, hypercalciuria, failure in urine acidification and protein endocytosis, which could explain the symptoms exhibited by XLN patients.

ClC-5 chloride channel and kidney stones: what is the link?

Nephrolithiasis is one of the most common diseases in the Western world. The disease manifests itself with intensive pain, sporadic infections, and, sometimes, renal failure. The symptoms are due to the appearance of urinary stones (calculi) which are formed mainly by calcium salts. These calcium salts precipitate in the renal papillae and/or within the collecting ducts. Inherited forms of nephrolithiasis related to chromosome X (X-linked hypercalciuric nephrolithiasis or XLN) have been recently described. Hypercalciuria, nephrocalcinosis, and male predominance are the major characteristics of these diseases. The gene responsible for the XLN forms of kidney stones was cloned and characterized as a chloride channel called ClC-5. The ClC-5 chloride channel belongs to a superfamily of voltage-gated chloride channels, whose physiological roles are not completely understood. The objective of the present review is to identify recent advances in the molecular pathology of nephrolithiasis, with emphasis on XLN. We also try to establish a link between a chloride channel like ClC-5, hypercalciuria, failure in urine acidification and protein endocytosis, which could explain the symptoms exhibited by XLN patients