Recurrence of cryptogenic stroke or TIA in patients with patent foramen ovale successfully treated by using different kind of percutaneous occluder devices: five-year follow-up.

AIM: Cryptogenic stroke remains the final diagnosis in 40% of ischemic acute cerebrovascular events. Until now there are no clinical evidences that the percutaneous closure of PFO is able to prevent the recurrence of stroke or transient ischemic attack (TIA). The aim of this study was to evaluate the incidence of recurrence in patients successfully treated by percutaneous closure of PFO with different occluder devices by using TCD, TTE and clinical evaluation. METHODS: From February 2004 to November 2009, 72 pts, (40 females and 32 males; average age 46 yrs, range 14-66), admitted with diagnosis of recurrent ischemic neurologic events (58 stroke and 14 TIA) underwent percutaneous closure of PFO. Thirty-one (43%) of the 72 patients had a concomitant history of migraine, 16 (52%) of whom with aura. Five different occluder devices were used, with a total amount of 74 implants. All pts were studied during the follow-up by clinical evaluation (Rankin modified scale), TCD and TTE. RESULTS: Successful device deployment is achieved in 100% of pts without any periprocedural major complication. Only in two pts atrial arrhythmia have occurred. All pts was discharged within 3 days in good overall conditions. In all pts a double antiplatelet regimen was adopted. The follow-up was complete in 100% of the cases (median 30, range 3-58 months ). At five years, there was no recurrent stroke or TIA, and no new cerebral lesions developed by MRI in those patients with residual shunt. Moreover, in 65 (90%) of them the Rankin scale significantly (P<0.0001) reduced to 0 whereas only in 2 pts score 1 was reached. In 19 (61%) of the 31pts with concomitant migraine, the intensity and the frequency of the attacks significantly (P<0.0001) decreased over time. At the TCD, 5 pts (7%) resulted positive for microembolic signals but, only 1 of them, was successfully treated for an associate defect. The TTE evaluation showed however an optimal sealing of all the devices without signs of erosion, incomplete closure and thrombus formation around the device. CONCLUSION: Our experience suggests that percutaneous treatment of PFO is safe and beneficial at the medium term follow-up for secondary prevention since able to prevent the clinical recurrence of acute cerebrovascular events irrespective of the device used.

Endothelial colony-forming cells and pro-angiogenic cells: clarifying definitions and their potential role in mitigating acute kidney injury.

Acute kidney injury (AKI) represents a significant clinical concern that is associated with high mortality rates and also represents a significant risk factor for the development of chronic kidney disease (CKD). This article will consider alterations in renal endothelial function in the setting of AKI that may underlie impairment in renal perfusion and how inefficient vascular repair may manifest post-AKI and contribute to the potential transition to CKD. We provide updated terminology for cells previously classified as 'endothelial progenitor' that may mediate vascular repair such as pro-angiogenic cells and endothelial colony-forming cells. We consider how endothelial repair may be mediated by these different cell types following vascular injury, particularly in models of AKI. We further summarize the potential ability of these different cells to mitigate the severity of AKI, improve perfusion and maintain vascular structure in pre-clinical studies.

Basic fibroblast growth factor receptor in the rat adrenal cortex: effects of suramin and unilateral adrenalectomy on receptor numbers.

Previous studies have suggested that basic fibroblast growth factor (bFGF) is involved in the mediation of the compensatory adrenal growth response. These studies were undertaken to identify the bFGF receptor in the rat adrenal cortex and determine bFGF receptor levels in vivo. Initial studies using primary cultures of rat glomerulosa cells demonstrated a high affinity binding site with a Kd of 10 pM, consistent with reported values for the bFGF receptor; however, these results could not be demonstrated in capsule-glomerulosa tissue. Using autoradiography to verify the existence of bFGF receptors in vivo, heparin-insensitive [125I]bFGF-binding sites were concentrated primarily in the capsule and glomerulosa of the adrenal cortex, suggesting the presence of FGF receptors. The presence of bFGF receptors was further verified by demonstration of internalization of [125I]bFGF into cells of capsule-glomerulosa preps. This approach was used to demonstrate that suramin (a bFGF antagonist) pretreatment of rats results in bFGF receptor up-regulation in the adrenal cortex. In addition, we demonstrated a decrease in bFGF internalization in the remaining adrenal 24 h after unilateral adrenalectomy, suggesting the utilization of bFGF during the compensatory adrenal growth response. Together, these data support a role for bFGF in autocrine stimulation of the adrenal cortex and in the compensatory adrenal growth response.

Vasodilatation in the rat dorsal hindpaw induced by activation of sensory neurons is reduced by paclitaxel.

Peripheral neuropathy is a major side effect following treatment with the cancer chemotherapeutic drug paclitaxel. Whether paclitaxel-induced peripheral neuropathy is secondary to altered function of small diameter sensory neurons remains controversial. To ascertain whether the function of the small diameter sensory neurons was altered following systemic administration of paclitaxel, we injected male Sprague Dawley rats with 1mg/kg paclitaxel every other day for a total of four doses and examined vasodilatation in the hindpaw at day 14 as an indirect measure of calcitonin gene related peptide (CGRP) release. In paclitaxel-treated rats, the vasodilatation induced by either intradermal injection of capsaicin into the hindpaw or electrical stimulation of the sciatic nerve was significantly attenuated in comparison to vehicle-injected animals. Paclitaxel treatment, however, did not affect direct vasodilatation induced by intradermal injection of methacholine or CGRP, demonstrating that the blood vessels' ability to dilate was intact. Paclitaxel treatment did not alter the compound action potentials or conduction velocity of C-fibers. The stimulated release of CGRP from the central terminals in the spinal cord was not altered in paclitaxel-injected animals. These results suggest that paclitaxel affects the peripheral endings of sensory neurons to alter transmitter release, and this may contribute to the symptoms seen in neuropathy.

The endothelial cell in ischemic acute kidney injury: implications for acute and chronic function.

Recent evidence suggests that injury to the renal vasculature may play an important role in the pathogenesis of both early and chronic ischemic acute kidney injury (AKI). Established and new data support the suggestion that vascular injury, in particular, endothelial cell injury, participates in the extent and maintenance of AKI by pathways that are related to vascular tone. Early alterations in peritubular capillary blood flow during reperfusion has been documented and associated with loss of normal endothelial cell function, which can be replaced pharmacologically or with cell replacement interventions. Distorted peritubular capillary morphology is associated with loss of barrier function that may contribute to early alterations in vascular stasis. In addition, ischemia induces alterations in endothelial cells that may promote inflammation and procoagulant activity, thus contributing to vascular congestion. Reductions in microvasculature density may play a critical part in the progression of chronic kidney disease following initial recovery from ischemia/reperfusion-induced AKI. The exact nature of how capillary loss alters renal function and predisposes renal disease is thought to be due at least in part to hypoxia. Finally, the loss of endothelial cell function may represent an important therapeutic target in which nitric oxide, vascular trophic support, and/or endothelial progenitor cells may show potential importance in ameliorating the acute and/or chronic effects of ischemic AKI.

The transforming growth factor beta system in kidney disease and repair: recent progress and future directions.

Transforming growth factor beta is a multifunctional polypeptide growth factor implicated in a variety of renal diseases. The expression of transforming growth factor beta is enhanced in renal diseases and available evidence suggests that its activity in promoting the synthesis of extracellular matrix plays a crucial role in fibrotic deposition and the decline in renal function. Transforming growth factor beta is, however, also expressed in response to renal injury and may play an important role in normal repair processes. It appears that renal diseases may result from the inappropriate regulation of transforming growth factor beta expression. The determination of the factors that mediate transforming growth factor beta activity will be of primary importance in elucidating the mechanisms leading to renal disease or repair after injury. Both in-vitro and in-vivo studies have demonstrated that proteolytic activity, thrombospondin-1, elevated glucose, angiotensin II, oxidant stress and hemodynamic forces regulate transforming growth factor beta activity through both transcriptional and post-transcriptional mechanisms. In some cases, therapies that may partly disrupt renal transforming growth factor beta activity have shown promise in slowing the progression to end-stage renal disease.

Basic fibroblast growth factor may mediate proliferation in the compensatory adrenal growth response.

We have investigated the role of basic fibroblast growth factor (bFGF) in the neurally mediated compensatory adrenal growth response. Unilateral adrenalectomy resulted in a 13, 6, and 22% increase in adrenal weight, protein, and DNA content, respectively, and 33-40% increases in the rate of cell proliferation measured by [3H]thymidine incorporation in vitro. Three forms of bFGF, approximately 18.6, 21, and 22.5 kDa, were identified in rat adrenals by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot. bFGF was localized immunocytochemically in cells of the glomerulosa and the medulla. bFGF stimulated a 68-80% increase in the rate of DNA synthesis in adrenal capsule-glomerulosa preparations in vitro. Suramin (0.1 mM), a growth factor antagonist, blocked bFGF receptor interaction in vitro and, at 200 mg/kg given 5-7 days before adrenal surgery, blocked compensatory growth. Conversely, at 2.0 mg/kg, suramin significantly enhanced the compensatory growth response, perhaps caused by suramin-induced bFGF receptor upregulation, since suramin pretreatment also enhanced DNA synthesis in response to exogenous bFGF in vitro. These results suggest that bFGF may mediate proliferation in the compensatory adrenal growth response.

TGF-beta in renal development and renal growth.

Organogenesis of the metanephric kidney is regulated by a number of polypeptide growth factors. Members of the TGF-beta family of growth factors have been shown to be produced in kidney during its development. Available evidence suggests that some of these members play key roles in metanephrogenesis by regulating the process of ureteric bud arborization. The regeneration of the S3 segment of the proximal tubule that occurs following ischemic injury recapitulates in many ways the renal developmental paradigm. The expression of TGF-beta in regenerating kidney is tightly regulated postischemia. We suggest that TGF-beta plays a key role in the repair process following injury and mediates some of the cellular events common to both regeneration and nephrogenesis.

Expression of bcl-2 and bax in regenerating rat renal tubules following ischemic injury.

To define potential roles for bcl-2 and bax in adult kidney as regulators of regeneration, their expressions were characterized postischemic injury. A 2.1-fold increase in levels of renal bcl-2 mRNA occurred within 24 h of injury relative to levels in kidney of sham-operated control rats. The levels of bcl-2 mRNA remained elevated for 3 days but returned to baseline by day 5 postischemia. In situ hybridization of kidneys from sham-operated rats demonstrated faint expression of bcl-2 mRNA localized diffusely throughout the nephron. After renal injury, the expression of bcl-2 mRNA was markedly enhanced in regenerating proximal tubule cells relining the basement membrane. Immunohistochemistry showed a similar localization for bcl-2 protein. Levels of bax mRNA in kidney were elevated beginning at 24 h postischemia and remained elevated for 7 days postinjury. Bax mRNA and bax protein were colocalized to regenerating proximal tubules postischemia and were prominently expressed in papillary proliferations. We conclude that the expressions of bcl-2 and bax in kidney are enhanced in a predictable pattern following acute ischemic injury. Our findings suggest that these regulators of apoptosis play key roles in the process of repair of the damaged proximal tubule postischemia.

Extracellular matrix-related genes in kidney after ischemic injury: potential role for TGF-beta in repair.

The renal expression of transforming growth factor-beta1 (TGF-beta1) is enhanced following induction of ischemic injury in rat. In cultured renal cells, TGF-beta stimulates the synthesis of extracellular matrix. To link TGF-beta1 expression with the regulation of extracellular matrix postischemia, we characterized the expression of several genes known to regulate extracellular matrix synthesis at various times during recovery from acute ischemic renal injury in rat. Levels of mRNA for plasminogen activator inhibitor-1 (PAI-1), tissue inhibitor of metalloprotease-1 (TIMP-1), alpha1(IV) collagen, and fibronectin-EIIIA (FN-EIIIA) mRNAs were significantly enhanced in kidneys within 12 h to 3 days after injury and remained elevated at 7-28 days postischemia relative to levels in kidneys of sham-operated controls. PAI-1 mRNA and peptide were localized in regenerating proximal tubules at 3 and 7 days postischemic injury. alpha1(IV) Collagen and FN-EIIIA mRNAs were expressed primarily in regenerating proximal tubule cells. Immunoreactivity for FN-EIIIA was enhanced in the tubular basement membrane (TBM) of regenerating proximal tubules, and alpha1(IV) collagen immunoreactivity was detected in thickened tubulointerstitial spaces. In contrast, TIMP-1 immunoreactivity was enhanced in distal nephron structures postischemia. Immunoneutralization of TGF-beta in vivo attenuated the increases in FN-EIIIA, alpha1(IV) collagen, PAI-1, and TIMP-1 mRNAs by 52%, 73%, 43%, and 27%, respectively. These data are consistent with TGF-beta expression postischemic injury participating in renal regeneration of extracellular matrix homeostasis in the proximal TBM.

Renal ischemic injury results in permanent damage to peritubular capillaries and influences long-term function.

Acute episodes of severe renal ischemia result in acute renal failure (ARF). These episodes are followed by a characteristic recovery and repair response, whereby tubular morphology and renal function appear completely restored within approximately 1 mo. However, the chronic effects of such an injury have not been well studied. Male rats were subjected to 60-min bilateral ischemia followed by reperfusion, yielding a characteristic injury. Postischemic animals manifested severe diuresis, peaking at 1 wk postinjury (volume: >45 ml/day, ARF vs. 18 ml/day, sham; P < 0.05). Urine flow subsequently declined but remained significantly elevated vs. sham animals for a 40-wk period. The prolonged alteration in urinary concentrating ability was attributable, in part, to a diminished capacity to generate a hypertonic medullary interstitium. By week 16, proteinuria developed in the post-ARF group and progressed for the duration of the study. Histological examination revealed essentially normal tubular morphology at 4 and 8 wk postinjury but the development of tubulointerstitial fibrosis at 40 wk. Transforming growth factor (TGF)-beta1 expression was elevated at 40 wk, but not at 4 and 8 wk postinjury. Microfil analysis revealed an approximately 30-50% reduction in peritubular capillary density in the inner stripe of the outer medulla at 4, 8, and 40 wk in post-ARF groups vs. sham animals. In addition, post-ARF rats manifested a significant pressor response to a low dose of ANG II (15 ng x kg(-1) x min(-1)). We hypothesize that severe ischemic injury results in a permanent alteration of renal capillary density, contributing to a urinary concentrating defect and the predisposition toward the development of renal fibrosis.

Increased transforming growth factor-beta 1 expression in regenerating rat renal tubules following ischemic injury.

To gain insight into the role that transforming growth factor-beta 1 (TGF-beta 1) plays in the regeneration of kidneys following acute renal failure, we characterized the expression of TGF-beta 1 mRNA and the expression of active and latent TGF-beta peptide at various times during recovery from acute ischemic injury in rat. Levels of whole kidney TGF-beta 1 mRNA were elevated significantly at 12 h postinjury (1.5-fold vs. sham-operated controls), and by 24 h postinjury were elevated by 3.6-fold. Levels remained elevated for 14 days following ischemia, but were no longer elevated at 28 days postinjury. In situ hybridization demonstrated that the elevated expression of TGF-beta 1 was localized predominantly to cells in the regenerating tubules in the outer medulla. When examined at 14 days postischemia, levels of TGF-beta 1 mRNA were elevated in the outer medulla only in tubules that appeared incompletely regenerated. Immunohistochemical staining localized active TGF-beta to the lumen of proximal tubules in control animals and in desquamated and regenerating tubular epithelial cells following ischemia. TGF-beta 1 latency-associated peptide was present intracellularly in proximal tubules of sham-operated rats and reduced following ischemia. We hypothesize that endogenous renal TGF-beta serves to promote tissue regeneration following acute injury via an autocrine or paracrine mechanism.

The human plasminogen activator inhibitor type I gene promoter targets to kidney.

The plasminogen activator inhibitor type 1 (PAI-1) gene encodes the physiological inhibitor of tissue-type and urokinase-type plasminogen activators and is induced by cytokines such as transforming growth factor-beta (TGF-beta). Studies have identified DNA sequence elements within the first 1.3 kb of the 5'-upstream DNA that mediate cytokine responsiveness in transfected cells in vitro. However, the DNA sequences that mediate PAI-1 expression in vivo have not yet been delineated. To define these regulatory sequences, we generated transgenic mice that expressed a hybrid gene comprising sequences between -1,272 and +75 of the human PAI-1 gene ligated to a LacZ reporter gene. Transgene expression detected in two independent lines was observed only in kidney from embryonic day 13 to adult and was seen primarily in proximal tubule cells of the outer medulla. Transgene expression and activity were unchanged in response to TGF-beta and remained restricted to kidney. Thus we have identified a promoter region within the PAI-1 gene that targets transgene expression to kidney but, unlike the native promoter, is unresponsive to TGF-beta in the experimental protocol used.