Essential regulatory elements for NHE3 gene transcription in renal proximal tubule cells

The objectives of the present study were to identify the cis-elements of the promoter absolutely required for the efficient rat NHE3 gene transcription and to locate positive and negative regulatory elements in the 5’-flanking sequence (5’FS), which might modulate the gene expression in proximal tubules, and to compare this result to those reported for intestinal cell lines. We analyzed the promoter activity of different 5’FS segments of the rat NHE3 gene, in the OKP renal proximal tubule cell line by measuring the activity of the reporter gene luciferase. Because the segment spanning the first 157 bp of 5’FS was the most active it was studied in more detail by sequential deletions, point mutations, and gel shift assays. The essential elements for gene transcription are in the region -85 to -33, where we can identify consensual binding sites for Sp1 and EGR-1, which are relevant to NHE3 gene basal transcription. Although a low level of transcription is still possible when the first 25 bp of the 5’FS are used as promoter, efficient transcription only occurs with 44 bp of 5’FS. There are negative regulatory elements in the segments spanning -1196 to -889 and -467 to -152, and positive enhancers between -889 and -479 bp of 5’FS. Transcription factors in the OKP cell nuclear extract efficiently bound to DNA elements of rat NHE3 promoter as demonstrated by gel shift assays, suggesting a high level of similarity between transcription factors of both species, including Sp1 and EGR-1.

Regulation of the renal proximal tubule second sodium pump by angiotensins

For several years it was believed that angiotensin II (Ang II) alone mediated the effects of the renin-angiotensin system. However, it has been observed that other peptides of this system, such as angiotensin-(1-7) (Ang-(1-7)), present biological activity. The effect of Ang II and Ang-(1-7) on renal sodium excretion has been associated, at least in part, with modulation of proximal tubule sodium reabsorption. In the present review, we discuss the evidence for the involvement of Na+-ATPase, called the second sodium pump, as a target for the actions of these compounds in the regulation of proximal tubule sodium reabsorption.

Effects of sirolimus alone or in combination with cyclosporine A on renal ischemia/reperfusion injury

Calcineurin inhibitors exacerbate ischemic injury in transplanted kidneys, but it is not known if sirolimus protects or exacerbates the transplanted kidney from ischemic injury. We determined the effects of sirolimus alone or in combination with cyclosporin A (CsA) on oxygenated and hypoxic/reoxygenated rat proximal tubules in the following in vitro groups containing 6-9 rats per group: sirolimus (10, 50, 100, 250, 500, and 1000 ηg/mL); CsA (100 µg/mL); sirolimus (50 and 250 ηg/mL) + CsA (100 µg/mL); control; vehicle (20% ethanol). For in vivo studies, 3-week-old Wistar rats (150-250 g) were submitted to left nephrectomy and 30-min renal artery clamping. Renal function and histological evaluation were performed 24 h and 7 days after ischemia (I) in five groups: sham, I, I + SRL (3 mg·kg-1·day-1, po), I + CsA (3 mg·kg-1·day-1, sc), I + SRL + CsA. Sirolimus did not injure oxygenated or hypoxic/reoxygenated proximal tubules and did not potentiate the tubular toxic effects of CsA. Neither drug affected the glomerular filtration rate (GFR) at 24 h. GFR was reduced in CsA-treated rats on day 7 (0.5 ± 0.1 mL/min) but not in rats receiving sirolimus + CsA (0.8 ± 0.1 mL/min) despite the reduction in renal blood flow (3.9 ± 0.5 mL/min). Acute tubular necrosis regeneration was similar for all groups. Sirolimus alone was not toxic and did not enhance hypoxia/reoxygenation injury or CsA toxicity to proximal tubules. Despite its hemodynamic effects, sirolimus protected post-ischemic kidneys against CsA toxicity.

Carcinoma renal dos ductos de Bellini

Two types primary epithelial tumours of the kidney have been distinguished, such as renal cell carcinoma (hypernephroma or Grawitz) deriving from proximal tubules and carcinoma arising in the urothelium of the kidney's collecting system. Mancilla-Jimenez e cols were the first to describe in 1976 an atypical papillary carcinoma of the kidney deriving from collecting duct system-Bellini duct carcinoma (BDC). In the World Healthy Organization classification it is listed as a rare carcinoma ( 1 % of the renal malignancies) originating in the renal medulla. Histologic examination shows both tubular and papillary architeture, which can lead to misinterpretation as renal cell or transitional cell carcinoma. Renal cell carcinoma originates from the metanephrogenic blastema and collecting duct carcinoma derived embryologicaly from the mesonephron Wolff duct. Renal cell carcinoma has been shown to express both cytokeratins and vimetin, whereas the distal convoluted tubule expresses only cytokeratins. BDC can be considered as a renal malignancy with a very bad prognosis compared to the other renal cell carcinoma. The best treatment is radical nephrectomy. A case of BDC is reported in a young black man, 27 year old with only history of light left back pain. Ultrasound and other image examinations showed a tumour about 6 cm in the middle and low left kidney. Patient was submitted to extraperitoneal radical nephectomy. Microscopic evaluation revealed kidney's collecting duct carcinoma with metastasis on two retroperitoneal lymphy nodes.

Effect of thyroparathyroidectomy on urinary acidification in diabetic rats

In previous studies we have shown stimulation of renal acid excretion in the proximal tubules of rats with diabetes of short duration, with no important alterations in glomerular hemodynamics; on the other hand, in thyroparathyroidectomized rats (TPTX model), a significant decrease in renal acid excretion, glomerular filtration rate (GFR) and renal plasma flow (RPF) was detected. Since important changes in the parathyroid hormone-vitamin D-Ca axis are observed in the diabetic state, the present study was undertaken to investigate the renal repercussions of thyroparathyroidectomy in rats previously made diabetic by streptozotocin (45 mg/kg). Four to 6 days after the induction of diabetes (DM), a group of rats were thyroparathyroidectomized (DM + TPTX). Renal functional parameters were evaluated by measuring the inulin and sodium para-aminohippurate clearance on the tenth day. The decrease in the GFR and RPF observed in TPTX was not reversed by diabetes since the same alterations were observed in DM + TPTX. Net acid (NA) excretion was unchanged in DM (6.19 ± 0.54), decreased in TPTX (3.76 ± 0.25) and returned to normal levels in DM + TPTX (5.54 ± 0.72) when compared to the control group (6.34 ± 0.14 µmol min-1 kg-1). The results suggest that PTH plays an important vasodilator role regarding glomerular hemodynamics, since in its absence the impairment in GFR and RPF was not reversed by the diabetic state. However, with respect to acid excretion, the presence of diabetes was able to overcome the negative stimulus represented by TPTX.

Human fetal malformations associated with the use of an angiotensin II receptor antagonist: Case Report

Introduction: The potential risks related to drug exposure during pregnancy represent a vast chapter in modern obstetrics and data regarding the safety of antihypertensive drugs during pregnancy are relatively scarce. Case report: A 37-year-old patient discovered her fifth pregnancy at our hospital after 26 weeks and 4 days of gestation. She reported a history of hypertension and was currently being treated with Losartan. Hospitalization was recommended for the patient and further evaluation of fetal vitality was performed. On the fourth day an ultrasound was performed, resulting in a severe oligohydramnios, fetal centralization and abnormal ductus venosus. After 36 hours, the newborn died. Pathologic evaluation: At autopsy, the skullcap had large fontanels and deficient ossification. The kidneys were slightly enlarged. A microscopic examination detected underdevelopment of the tubules and the presence of some dilated lumens. Immunohistochemical detection of epithelial membrane antigen was positive. Immunoreactivity of CD 15 was also assayed to characterize the proximal tubules, and lumen collapse was observed in some regions. Discussion: Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor antagonists (ARAs) are among the most widely prescribed drugs for hypertension. They are often used by hypertensive women who are considering become pregnant. While their fetal toxicity in the second or third trimesters has been documented, their teratogenic effect during the first trimester has only recently been demonstrated. Conclusion: Constant awareness by physicians and patients should be encouraged, particularly in regard to the prescription of antihypertensive drugs in women of childbearing age who are or intend to become pregnant.

Effect of metabolic acidosis on renal tubular sodium handling in rats as determined by lithium clearance

Systemic metabolic acidosis is known to cause a decrease in salt and water reabsorption by the kidney. We have used renal lithium clearance to investigate the effect of chronic, NH4Cl-induced metabolic acidosis on the renal handling of Na+ in male Wistar-Hannover rats (200-250 g). Chronic acidosis (pH 7.16 ± 0.13) caused a sustained increase in renal fractional Na+ excretion (267.9 ± 36.4%), accompanied by an increase in fractional proximal (113.3 ± 3.6%) and post-proximal (179.7 ± 20.2%) Na+ and urinary K+ (163.4 ± 5.6%) excretion when compared to control and pair-fed rats. These differences occurred in spite of an unchanged creatinine clearance and Na+ filtered load. A lower final body weight was observed in the acidotic (232 ± 4.6 g) and pair-fed (225 ± 3.6 g) rats compared to the controls (258 ± 3.7 g). In contrast, there was a significant increase in the kidney weights of acidotic rats (1.73 ± 0.05 g) compared to the other experimental groups (control, 1.46 ± 0.05 g; pair-fed, 1.4 ± 0.05 g). We suggest that altered renal Na+ and K+ handling in acidotic rats may result from a reciprocal relationship between the level of metabolism in renal tubules and ion transport.

RENAL HISTOPATHOLOGICAL FINDINGS IN DOGS WITH VISCERAL LEISHMANIASIS

Visceral leishmaniasis affects various organs including the kidneys; which can lead to renal failure and death. In order to verify this renal involvement, material was evaluated from 100 dogs naturally infected and with serological diagnosis of canine visceral leishmaniasis (CVL). Inflammatory changes were present in 25.3% of the tubules, in 67.0% of interstitium and in 52.0% of glomeruli. There was no significant difference (p > 0.05) between the presence of glomerulonephritis in symptomatic and oligosymptomatic dogs. The membranous and membranoproliferative glomerulonephritis were the most frequent, both with 18.0% frequency, followed by focal segmental glomerulosclerosis with 14.0%. Changes such as cylindruria, tubular and fibrosis hypertrophy, periglomerular inflammatory infiltrate, and multifocal and diffuse peritubular inflammatory infiltrate were observed. The findings are consistent with those of other authors indicating that renal involvement is common in CVL and the standards of membranous and membranoploriferative glomerulonephritis, as well as the tubulointerstitial involvement, are frequent.

Aspectos da função renal em portadores do vírus da imunodeficiência humana

Verificou-se a ocorrência de alterações em alguns parâmetros da função renal de indivíduos infectados pelo virus da imunodeficiência humana (HIV), assintomáticos. Foram estudados 47 indivíduos, realizando-se provas funcionais renais: depuração de creatinina endógena, depuração de água livre, depuração osmolar, reabsorção tubular proximal e distal de sódio, excreção fracional de sódio e potássio e pH urinário. Os resultados revelaram diferenças significantes (p < 0,05) no pH urinário, maior no grupo HIV (6,36 ± 0,41), do que nos controles (6,02 ± 0,41); na depuração de água livre, que indicou reabsorção de água maior no grupo HIV (1,00 ± 0,64ml/min), do que nos controles (0,53 ± 0,48ml/min) e na depuração osmolar, que foi 2,00 ± 0,83ml/min no grupo HIV e 1,57 ± 0,48ml/min nos controles. O restante dos indicadores de função renal estudados não se mostraram diferentes estatisticamente entre um e outro grupo. Concluiu-se que essas diferenças são significativas, apesar de os valores absolutos estarem dentro da normalidade, pois podem estar associadas a alterações evolutivas tardias da doença, tais como o aumento na frequência de infecções do trato urinário e a hiponatremia dilucional. Mais estudos são necessários para se confirmarem essas hipóteses.

Envolvimento da função renal em pacientes com leishmaniose visceral (calazar)

Envolvimento da função renal em pacientes com leishmaniose visceral (calazar). Apresenta-se estudo prospectivo de 11 pacientes com LV, com o intuito de verificar as repercussões clínico-laboratoriais da função renal na doença. Realizou-se análises laboratoriais das amostras de sangue e urina, colhidas logo após confirmação diagnóstica, através do encontro de leishmanias no aspirado de médula óssea. Dois (18%) pacientes apresentaram complicações associadas a LV. Cinco (45,4%) apresentaram hematúria macroscópica e em um caso (No.9) manifestações clínicas compatíveis com síndrome nefrítica aguda. Os resultados dos exames de urina mostraram: proteinúria em 10 (90,9%) pacientes, hematúria 7 (63,6%) e leucocitúria em 6 (54,5%) casos. Nove (81,8%) pacientes apresentaram níveis elevados de microalbuminúria caracterizando lesão glomerular. A presença de tubulopatia proximal medida através da proteína ligadora de retinol, foi observada em 5 (45,4%) casos. Concluiu-se que o envolvimento renal se fez presente na maioria dos pacientes, contribuindo para a gravidade da doença.

Kidney function after left renal vein ligation in the dog

The ligature of the left renal vein is an alternative whenever this vessel is injured. The purpose of this study was to evaluate the capacity of the affluents of the left renal vein, proximal to the ligature, to maintain tissue vitality and function of the left kidney. Fifteen mongrel male dogs were divided in 3 groups of 5 dogs: Group I (control) - a laparotomy was performed, and the abdominal structures were only identified; Group II - the left renal vein was tied, close to vena cava; Group III - the same procedure as for Group II and a right nephrectomy. Blood urea nitrogen and serum creatinine levels were measured before the procedure, and every 3 days during 4 weeks in the postoperative period. Renal arteriography and an excretory urogram were performed on the animals that survived 60 days. Thereafter, or immediately after precocious death, the kidneys were removed for histological examination. All the animals of Group III died before two months (mean = 10.5 +-3.2 days), while the animals of Group II survived during that period. There was a complete exclusion of the left kidney in all dogs that underwent renal vein ligature. In the animals of Group II, the renal cortico-medullary limits could not be identified. At microscopy, the aspect was suggestive of nephrosclerosis. In the animals of Group III, the left kidney was enlarged, and a great amount of intravascular and intrapelvic blood clots were observed. At microscopy, extensive areas of necrosis, inflammatory infiltration, and hemorrhage were identified. In conclusion, the tributaries of the renal vein were not sufficient to maintain the tissue vitality and function of the left kidney after ligature of its main vein.

Observations on the morphology of Pomacea lineata (Spix, 1827) (Mollusca, Ampullariidae)

This paper deals with the morpholgy of Pomacea lineata (Spix, 1827) collected at its type locality. The shell is globose, moderately heavy, horn-colored with brown spiral bands; apex subelevated; 4 - 5 rounded whorls increasing in diameter rather rapidly, separated by deep suture. Aperture large and ovoid; outer lip sharp; umbilicus narrow and deep; operculum concentric, corneous. Ratios: shell width/shell length = 0.74 - 0.83 (mean 0.78); spire length/shell length = 0.10 - 0.18 (mean 0.13); aperture length/shell length = 0.70 - 0.77 (mean 0.73). The animal is longisiphonate. Renal organ brownish with marked invagination at its right edge. Ureter elongated with its long axis transverse to the main axis of the kidney. The radula is taenioglossate (2.1.1.1.2) and has on average 35 transverse rows of teeth. The form and arrangement of the radula teeth are nearly the same as in other Ampullariidae. The testis is cream-colored and lies in the first three whorls of the spire. Spermiduct uniformly narrow, running to the base of the spire. Seminal vesicle whitish, slightly pressed dorsoventrally. Prostate cylindric and thick, similar in color to the testis. Penis whiplike, with a closed circular spermiduct. Penis pouch ovoid completely envelping the penis. Penis sheath elongated, broad prosimally, tapering distally. Its inner surface shows a longitudinal channel along its proximal half and two glands, one on the middle and the other apical. Ovary composed of branched whitish tubules situated on the surface of the digestive gland. Oviduct slender running along the columellar axis toward the base of the spire. Seminal receptalble tubiform, thick-walled and rounded proximally. Albumen gland large, pink, enclosing the receptacle and the spiral capsule gland. Vestigial male copulatory apparatus (penis and its sheath) present in all females examined.

Tratamento de hemorragia intestinal grave decorrente de hipertensão porta, por meio de esplenectomia subtotal e anastomose esplenorrenal proximal

OBJETIVO: Um dos maiores desafios no tratamento da hipertensão porta é o sangramento de varizes intestinais. O objetivo deste artigo é apresentar um novo tratamento para hemorragia entérica grave provocada por hipertensão porta cirrótica, utilizando a esplenectomia subtotal combinada com derivação esplenorrenal proximal. TÉCNICA: Uma paciente de 64 anos apresentou sangramento intenso proveniente de varizes em alça jejunal em Y de Roux, para derivação biliodigestiva, após lesão coledociana, complicada com cirrose hepática. O procedimento consistiu em esplenectomia subtotal, preservando o pólo superior do baço, suprido apenas pelos vasos esplenogástricos, e anastomose término-lateral da veia esplênica, em sua extremidade proximal, à veia renal esquerda. RESULTADOS: Esse procedimento foi seguro, sem sangramento maior, dificuldade técnica ou complicação. No acompanhamento de 30 meses, a paciente não teve novos episódios de sangramento, a cirrose não avançou e, atualmente, encontra-se bem, sob controle. CONCLUSÃO: A esplenectomia subtotal combinada com derivação esplenorrenal proximal é uma boa alternativa operatória para tratar hemorragia proveniente de varizes intestinais, decorrentes de hipertensão porta.

Regulation of nephron acidification by corticosteroids

The present paper reviews work from our laboratories evaluating the importance of adrenal cortical hormones in acidification by proximal and cortical distal tubules. Proximal acidification was determined by stationary microperfusion, and measurement of bicarbonate reabsorption using luminal pH determination was performed with H+-ion-sensitive microelectrodes. Rats were adrenalectomized (ADX) 48 h before the experiments, and corticosteroids (aldosterone (A), corticosterone (B), and 18-OH corticosterone (18-OH-B)) were injected intramuscularly 100 and 40 min before the experiments. In ADX rats stationary pH increased significantly to 7.03 as compared to sham-operated rats (6.78). Bicarbonate reabsorption decreased from 2.65 &plusmn; 0.18 in sham-operated rats to 0.50 &plusmn; 0.07 nmol cm-2 s-1 after ADX. The administration of the three hormones stimulated proximal tubule acidification, reaching, however, only 47.2% of the sham values in aldosterone-treated rats. Distal nephron acidification was studied by measuring urine minus blood pCO2 differences (U-B pCO2) in bicarbonate-loaded rats treated as above. This pCO2 difference is used as a measure of the distal nephron ability to secrete H+ ions into an alkaline urine. U-B pCO2 decreased significantly from 39.9 &plusmn; 1.26 to 11.9 &plusmn; 1.99 mmHg in ADX rats. When corticosteroids were given to ADX rats before the experiment, U-B pCO2 increased significantly, but reached control levels only when aldosterone (two 3-&micro;g doses per rat) plus corticosterone (220 &micro;g) were given together. In order to control for the effect of aldosterone on distal transepithelial potential difference one group of rats was treated with amiloride, which blocks distal sodium channels. Amiloride-treated rats still showed a significant reduction in U-B pCO2 after ADX. Only corticosterone and 18-OH-B but not aldosterone increased U-B pCO2 back to the levels of sham-operated rats. These results show that corticosteroids stimulate renal tubule acidification both in proximal and distal nephrons and provide some clues about the mechanism of action of these steroids

Renal dysfunction in patients with sickle cell anemia or sickle cell trait

Patients with sickle cell anemia (Hb SS) or sickle cell trait (Hb AS) may present several types of renal dysfunction; however, comparison of the prevalence of these abnormalities between these two groups and correlation with the duration of disease in a large number of patients have not been thoroughly investigated. In a cross-sectional study using immunoenzymometric assays to measure tubular proteinuria, microalbuminuria, measurement of creatinine clearance, urinary osmolality and analysis of urine sediment, we evaluated glomerular and tubular renal function in 106 adults and children with Hb SS (N = 66) or Hb AS (N = 40) with no renal failure (glomerular filtration rate (GFR) >85 ml/min). The percentage of individuals with microalbuminuria was higher among Hb SS than among Hb AS patients (30 vs 8%, P<0.0001). The prevalence of microhematuria was similar in both groups (26 vs 30%, respectively). Increased urinary levels of retinol-binding protein or ß2-microglobulin were detected in only 3 Hb SS and 2 Hb AS patients. Urinary osmolality was reduced in patients with Hb SS or with Hb AS; however, it was particularly evident in Hb SS patients older than 15 years (median = 393 mOsm/kg, range = 366-469) compared with Hb AS patients (median = 541 mOsm/kg, range = 406-722). Thus, in addition to the frequently reported early reduction of urinary osmolality and increased GFR, nondysmorphic hematuria was found in 26 and 30% of patients with Hb SS or Hb AS, respectively. Microalbuminuria is an important marker of glomerular injury in patients with Hb SS and may also be demonstrated in some Hb AS individuals. Significant proximal tubular dysfunction is not a common feature in Hb SS and Hb AS population at this stage of the disease (i.e., GFR >85 ml/min).