Glibenclamide effects on renal function and histology after acute hemorrhage in rats under sevoflurane anesthesia

INTRODUCTION: Hypovolemia from hemorrhage evokes protective compensatory reactions, such as the renin-angiotensin system, which interferes in the clearance function and can lead to ischemia. This study was designed to evaluate the effects of glibenclamide, a K(+)(ATP) channel blocker, on renal function and histology in rats in a state of hemorrhagic shock under sevoflurane anesthesia. MATERIAL AND METHODS: Twenty Wistar rats were randomized into two groups of 10 animals each (G1 and G2), only one of which (G2) received intravenous glibenclamide (1 microg.g(-1)), 60 min before bleeding was begun. Both groups were anesthetized with sevoflurane and kept on spontaneous respiration with oxygen-air, while being bled of 30% of volemia in three stages with 10 min intervals. There was an evaluation of renal function - sodium para-aminohippurate and iothalamate clearances, filtration fraction, renal blood flow, renal vascular resistance - and renal histology. Renal function attributes were evaluated at three moments: M1 and M2, coinciding with the first and third stages of bleeding; and M3, 30 min after M2, when the animals were subjected to bilateral nephrectomy before being sacrificed. RESULTS: Significant differences were found in para-aminohippurate clearance, G1 < G2, and higher renal vascular resistance values were observed in G1. Histological examination showed the greater vulnerability of kidneys exposed to sevoflurane alone (G1) with higher scores of vascular and tubular dilatation. There were vascular congestion and tubular vacuolization only in G1. Necrosis and signs of tubular regeneration did not differ in both groups. CONCLUSION: Treatment with glibenclamide attenuated acutely the renal histological changes after hemorrhage in rats under sevoflurane anesthesia.     

Increased oxidative stress in the mouse adriamycin model of glomerulosclerosis is accompanied by deposition of ferric iron and altered GGT activity in renal cortex

Chronic renal failure evolves inevitable towards glomerular and tubulo-interstitial sclerosis. This pathological process involves a disturbed redox status of the kidney tissue, leading to irreversible damage. In this study we investigate in an adriamycin model of chronic renal failure in mice the evolution of in vivo hydrogen peroxide production, and the possible role of gamma-glutamyl transpeptidase and ferric iron in the process. Histological changes and ferric iron deposits are evaluated by histochemical staining. To evaluate oxidative stress residual catalase activity, TBARS formation and gamma-glutamyl transpeptidase activity are measured spectrophotometrically. While catalase activity remains the same, a decreased residual catalase activity indicates an increased formation of hydrogen peroxide. Both the activity of gamma-glutamyl transpeptidase and TBARS formation is increased at early stages of the disease. Ferric iron is clearly present in the proximal tubule. Twenty days after adriamycin injection all parameters decrease, probably due to the destruction of the tissue. Our data show the involvement of oxidative stress in the progression of adriamycin induced renal failure in mice. Both radical production and oxidative damage are measurable, while the altered activity of gamma-glutamyl transpeptidase and the deposition of ferric iron suggest the involvement of these factors in the development of a disturbed redox status in the kidney cortex.     

Dynamic time-resolved contrast-enhanced two-dimensional MR projection angiography of the pulmonary circulation: standard technique and clinical applications

OBJECTIVE: Time-resolved pulmonary two-dimensional MR projection angiography is a fast acquisition technique that allows the generation of dynamic projection angiograms by a method similar to that used to generate digital subtraction angiograms. MR images are obtained after subtracting the mask defined at the beginning of the sequence from later images, thus generating time-resolved continuous projection angiograms that depict the passage of a bolus through the pulmonary circulation. This article describes the application of this novel technique in three patients with pathologic conditions not previously described with this modality and two control subjects. CONCLUSION: The analysis of the findings on dynamic time-resolved contrast-enhanced two-dimensional MR projection angiography shows that this technique is useful not only in revealing morphologic changes associated with pulmonary disorders but also in following the passage of the bolus through the cardiopulmonary circulation. The latter capability allows qualitative detection of normal or abnormal pathways and thus is potentially of value in the assessment of several pulmonary disorders.     

Comparison of 1.0 M gadobutrol and 0.5 M gadopentate dimeglumine-enhanced MRI in 471 patients with known or suspected renal lesions: results of a multicenter, single-blind, interindividual, randomized clinical phase III trial

The purpose of this phase III clinical trial was to compare two different extracellular contrast agents, 1.0 M gadobutrol and 0.5 M gadopentate dimeglumine, for magnetic resonance imaging (MRI) in patients with known or suspected focal renal lesions. Using a multicenter, single-blind, interindividual, randomized study design, both contrast agents were compared in a total of 471 patients regarding their diagnostic accuracy, sensitivity, and specificity to correctly classify focal lesions of the kidney. To test for noninferiority the diagnostic accuracy rates for both contrast agents were compared with CT results based on a blinded reading. The average diagnostic accuracy across the three blinded readers (‘average reader’) was 83.7% for gadobutrol and 87.3% for gadopentate dimeglumine. The increase in accuracy from precontrast to combined precontrast and postcontrast MRI was 8.0% for gadobutrol and 6.9% for gadopentate dimeglumine. Sensitivity of the average reader was 85.2% for gadobutrol and 88.7% for gadopentate dimeglumine. Specificity of the average reader was 82.1% for gadobutrol and 86.1% for gadopentate dimeglumine. In conclusion, this study documents evidence for the noninferiority of a single i.v. bolus injection of 1.0 M gadobutrol compared with 0.5 M gadopentate dimeglumine in the diagnostic assessment of renal lesions with CE-MRI.

The role of the kallikrein-kinin system,matrix metalloproteinases,and tissue inhibitors of metalloproteinases in the early restenosis of covered stents in the femoropopliteal arterial segment

Objective

The purpose of this study was to investigate the roles of the kallikrein-kinin system and matrix metalloproteinases (MMPs) in the development of arterial restenosis attributable to intimal hyperplasia in the femoropopliteal arteries.

Klotho Lacks an FGF23‐Independent Role in Mineral Homeostasis

Fibroblast growth factor‐23 (FGF23) is a bone‐derived hormone regulating vitamin D hormone production and renal handling of minerals by signaling through an FGF receptor/αKlotho (Klotho) receptor complex. Whether Klotho has FGF23‐independent effects on mineral homeostasis is a controversial issue. Here, we aimed to shed more light on this controversy by comparing male and female triple knockout mice with simultaneous deficiency in Fgf23 and Klotho and a nonfunctioning vitamin D receptor (VDR) (Fgf23/Klotho/VDR) with double (Fgf23/VDR, Klotho/VDR, and Fgf23/Klotho) and single Fgf23, Klotho, and VDR mutants. As expected, 4‐week‐old Fgf23, Klotho, and Fgf23/Klotho knockout mice were hypercalcemic and hyperphosphatemic, whereas VDR, Fgf23/VDR, and Klotho/VDR mice on rescue diet were normocalcemic and normophosphatemic. Serum levels of calcium, phosphate, and sodium did not differ between 4‐week‐old triple Fgf23/Klotho/VDR and double Fgf23/VDR or Klotho/VDR knockout mice. Notably, 3‐month‐old Fgf23/Klotho/VDR triple knockout mice were indistinguishable from double Fgf23/VDR and Klotho/VDR compound mutants in terms of serum calcium, serum phosphate, serum sodium, and serum PTH, as well as urinary calcium and sodium excretion. Protein expression analysis revealed increased membrane abundance of sodium‐phosphate co‐transporter 2a (NaPi‐2a), and decreased expression of sodium‐chloride co‐transporter (NCC) and transient receptor potential cation channel subfamily V member 5 (TRPV5) in Fgf23/Klotho/VDR, Fgf23/VDR, and Klotho/VDR mice, relative to wild‐type and VDR mice, but no differences between triple and double knockouts. Further, ex vivo treatment of live kidney slices isolated from wild‐type and Klotho/VDR mice with soluble Klotho did not induce changes in intracellular phosphate, calcium or sodium accumulation assessed by two‐photon microscopy. In conclusion, our data suggest that the main physiological function of Klotho for mineral homeostasis in vivo is its role as co‐receptor mediating Fgf23 action. © 2017 American Society for Bone and Mineral Research.     

A Multiepitope Subunit Vaccine Conveys Protection against Extraintestinal Pathogenic Escherichia coli in Mice

Infections due to extraintestinal pathogenic Escherichia coli (ExPEC) are common in humans and animals and include urinary tract infections (from uropathogenic E. coli [UPEC]), septicemia, and wound infections. These infections result in significant morbidity and mortality and in high health care costs. In view of the increasing number of ExPEC infections and the ever-growing antibiotic resistance capability of ExPEC isolates, preventive measures such as an effective vaccine against ExPEC are desirable. An ExPEC vaccine may be cost-effective for select patient groups. Previous vaccine candidates consisted of single target proteins or whole ExPEC cells. Here we describe a subunit vaccine against ExPEC which is based on immunodominant epitopes of the virulence-associated ExPEC proteins FyuA, IroN, ChuA, IreA, Iha, and Usp. Using a novel approach of computer-aided design, two completely artificial genes were created, both encoding eight peptide domains derived from these ExPEC proteins. The recombinant expression of these two genes resulted in a protein vaccine directed against ExPEC but not against commensal E. coli of the gut flora. In mice, the vaccine was highly immunogenic, eliciting both strong humoral and cellular immune responses. Nasal application resulted in high secretory immunoglobulin A (sIgA) production, which was detectable on the mucosal surface of the urogenital tract. Finally, it conveyed protection, as shown by a significant reduction of bacterial load in a mouse model of ExPEC peritonitis. This study provides evidence that a novel vaccine design encompassing distinct epitopes of virulence-associated ExPEC proteins may represent a means for providing a protective and pathogen-specific vaccine.Escherichia coli is among the most common bacterial species encountered in clinical microbiology laboratories. Although E. coli strains represent a significant part of the normal gut flora, distinct E. coli pathotypes may cause either diarrhea and gastroenteritis (intestinal pathogenic E. coli [IPEC]) or infections outside the gastrointestinal tract (extraintestinal pathogenic E. coli [ExPEC]) (41).ExPEC strains can reside in the gut as part of the normal intestinal flora and can be isolated from 10 to 20% of healthy individuals (12). However, their entry into and colonization of extraintestinal sites result in a wide variety of infections, which occur in patients from the ambulatory, long-term-care, and hospital settings (23, 39). Diverse organs and anatomical sites are affected. Typical extraintestinal infections due to ExPEC include urinary tract infections (UTIs), surgical site infections, soft tissue infections, newborn meningitis, diverse intra-abdominal infections, and pneumonia. Among these, ascending urinary tract infection (pyelonephritis) most commonly leads to severe sepsis, which ranks as the 10th overall cause of death in the United States (13, 23, 31, 42). Since ExPEC strains are the major cause of most types of extraintestinal infection due to Gram-negative bacteria, prevention of ExPEC infections is a desirable goal from both medical and economic viewpoints (39).In the past, ExPEC strains were usually highly susceptible to common antibiotics such as ampicillin and trimethoprim-sulfamethoxazole (SXT). However, in recent years, the prevalence of E. coli resistance to various classes of antibiotics has risen progressively, becoming a major concern in both hospitals and the community. For example, resistance to SXT, the traditional drug of choice for uncomplicated UTIs, has increased each year worldwide (17, 18). Moreover, many clinical ExPEC isolates have acquired genes encoding extended-spectrum β-lactamases (ESBLs), which confer resistance to extended-spectrum cephalosporins and aztreonam (50). ESBL-positive ExPEC strains frequently contain additional resistance determinants, e.g., for aminoglycosides and tetracyclines. Thus, emerging antimicrobial resistance likely will make the future management of extraintestinal E. coli infections more difficult and costly than ever. Furthermore, the incidence of serious extraintestinal infection due to E. coli increases with age (2, 30), and as the proportion of elderly patients increases, it is likely that so will the number of extraintestinal E. coli infections. Thus, a preventive strategy, such as vaccinations, is very desirable to counteract these infections.An ideal vaccine target should be (i) exposed on the bacterial surface and (ii) widely distributed among clinical ExPEC isolates but not among commensal E. coli strains of the gut flora. Furthermore, it should (iii) possess epitopes that are conserved across diverse ExPEC strains and (iv) elicit a protective immune response. Other desirable characteristics of vaccine targets include (v) increased expression at the site of infection and (vi) a role in the pathogenesis of disease.In the present study, we developed a novel multiepitope subunit vaccine against ExPEC infection which fulfils these criteria. We hypothesized that subunits of the E. coli outer membrane siderophore receptors FyuA, IroN, and IutA, the heme receptor ChuA, and the uropathogenic E. coli (UPEC)-specific protein UspA could be used as vaccine targets to prevent the majority of infections due to extraintestinal E. coli. The goals of this study were (i) to use computer-predicted immunogenic epitopes of the outer protein loops of these proteins in a rational vaccine approach to form two artificial chimeric polypeptides, (ii) to apply either of these two novel multiepitope subunit vaccines by the nasal route to elicit both strong humoral and cellular immune responses, and (iii) to provide a high degree of protection in a mouse model of ExPEC peritonitis.