Effects of renal denervation of the contralateral kidney on blood pressure and sodium and eicosanoid excretion in the chronic phase of two-kidney, one-clip renovascular hypertension in rats

Organ bioengineering for the newborn

Regenerative medicine has recently been established as an emerging interdisciplinary field focused on the repair; replacement or regeneration of cells, tissues and organs. It involves various disciplines, which are focused on different aspects of the regeneration process such as cell biology, gene therapy, bioengineering, material science and pharmacology. In this article, we will outline progress on tissue engineering of specific tissues and organs relevant to paediatric surgery.

Role of renal nerves in the treatment of renovascular hypertensive rats with L-arginine

The purpose was to determine the role of renal nerves in mediating the effects of antihypertensive treatment with L-arginine in a renovascular hypertension model. The 2K1C (two-kidney one-clip model) hypertensive rats were submitted to bilateral surgical-pharmacological renal denervation. The animals were subdivided into six experimental groups: normotensive control rats (SHAM), 2K1C rats, 2K1C rats treated with L-arginine (2K1C + L-arg), denervated normotensive (DN) rats, denervated 2K1C (2K1C + DN) rats, and denervated 2K1C + L-arg (2K1C + DN + L-arg) rats. Arterial blood pressure, water intake, urine volume, and sodium excretion were measured. The 2K1C rats exhibited an increase in the mean arterial pressure (MAP) (from 106 ± 3 to 183 ± 5.8 mmHg, P < 0.01), whereas L-arg treatment induced a reduction in the MAP (143 ± 3.4 mmHg) without lowering it to the control level. Renal nerve denervation reduced the MAP to normotensive levels in 2K1C rats with or without chronic L-arg treatment. L-arg and denervation induced increases in water intake and urine volume, and L-arg caused a significant natriuretic effect. Our results suggest that renal sympathetic activity participates in the genesis and the maintenance of the hypertension and also demonstrate that treatment with L-arg alone is incapable of normalizing the MAP and that the effect of such treatment is not additive with the effect of kidney denervation.

Renal sympathetic nervous system and the effects of denervation on renal arteries

Resistant hypertension is associated with chronic activation of the sympathetic nervous system resulting in various comorbidities. The prevalence of resistant hypertension is often under estimated due to various reasons. Activation of sympathetic nervous system at the renal- as well as systemic- level contributes to the increased level of catecholamines and resulting increase in the blood pressure. This increased activity was demonstrated by increased muscle sympathetic nerve activity and renal and total body noradrenaline spillover. Apart from the hypertension, it is hypothesized to be associated with insulin resistance, congestive heart failure and obstructive sleep apnea. Renal denervation is a novel procedure where the sympathetic afferent and efferent activity is reduced by various techniques and has been used successfully to treat drug-resistant hypertension improvement of various metabolic derangements. Renal denervation has the unique advantage of offering the denervation at the renal level, thus mitigating the systemic side effects. Renal denervation can be done by various techniques including radiofrequency ablation, ultrasound guided ablation and chemical ablation. Various trials evaluated the role of renal denervation in the management of resistant hypertension and have found promising results. More studies are underway to evaluate the role of renal denervation in patients presenting with resistant hypertension in different scenarios. Appropriate patient selection might be the key in determining the effectiveness of the procedure.

Human acellular matrix graft of tunica albuginea for penile reconstruction

INTRODUCTION

Penile curvature is one of the most common male conditions, affecting nearly 10% of men, and can impair sexual intercourse. Tunica albuginea (hTA) plays a key role in penile curvature, and reconstructive procedures may be necessary for its substitution. Although several grafts have been proposed for hTA repair, the ideal graft is not yet available.

AIM

The aim of this article is to evaluate a new human tunica albuginea acellular matrix (hTAAM) as potential graft for penile reconstructive procedures.

METHODS

Twelve penises were obtained during sex reassignment surgeries from male-to-female transsexual patients. After dissection, hTAs were assigned into two groups according to the decellularization methods: polyethylene glycol (PEG) 1000 method following ultraviolet-C radiation, and Triton X-100 modified method.

MAIN OUTCOME MEASURES

Structural analyses were assessed by hematoxilin and eosin, Masson's trichrome, Weigert's, and picrosirius-polarization staining methods. Total protein, total glycosaminoglycan (GAG), and nucleic acid (DNA and RNA) concentrations were assessed by specific biochemical analyses. Uniaxial strength tests were performed to evaluate biomechanical properties.

RESULTS

All hTAAMs presented no nuclear or cellular remnants. Total protein concentration was significantly higher in PEG 1000 hTAAM. Despite GAG concentration decreased significantly in hTAAM, Triton X-100 hTAAM retained the highest GAG concentration (1.0 ± 0.42 µg HexUr/mg dry tissue, P > 0.05). All decellularization methods were efficacious to remove nucleic acids. The maximal break point presented no difference between hTA and hTAAM groups (P > 0.05).

CONCLUSIONS

PEG 1000 and Triton X-100 decellularization methods provide equally successful hTAAMs, preserving original structural and biochemical properties.

Tissue engineering and stem cells: basic principles and applications in urology

To overcome problems of damaged urinary tract tissues and complications of current procedures, tissue engineering (TE) techniques and stem cell (SC) research have achieved great progress. Although diversity of techniques is used, urologists should know the basics. We carried out a literature review regarding the basic principles and applications of TE and SC technologies in the genitourinary tract. We carried out MEDLINE/PubMed searches for English articles until March 2010 using a combination of the following keywords: bladder, erectile dysfunction, kidney, prostate, Peyronie's disease, stem cells, stress urinary incontinence, testis, tissue engineering, ureter, urethra and urinary tract. Retrieved abstracts were checked, and full versions of relevant articles were obtained. Scientists have achieved great advances in basic science research. This is obvious by the tremendous increase in the number of publications. We divided this review in two topics; the first discusses basic science principles of TE and SC, whereas the second part delineates current clinical applications and advances in urological literature. TE and SC applications represent an alternative resource for treating complicated urological diseases. Despite the paucity of clinical trials, the promising results of animal models and continuous work represents the hope of treating various urological disorders with this technology.

Use of oxidized cellulose for corporal body grafting and suture-less correction of severe penile chordee: an experimental study in rabbits

OBJECTIVE

To evaluate the efficacy of oxidized cellulose, Surgicel(TM) (Johnson & Johnson Medical, New Brunswick, NJ, USA) for patching defects in the tunica albuginea in a rabbit model, with a future application to correct chordee.

MATERIALS AND METHODS

The study comprised nine New Zealand white male rabbits; a rectangular 15 x 5-mm defect was created in the ventral tunica albuginea that was covered by Surgicel. The skin was closed with no catheters left in situ after the procedure. The rabbits were killed in groups of three at 2, 6 and 12 weeks after surgery. The evaluation included cavernosography and histopathological examination of sections of the penis stained with haematoxylin and eosin, and Masson's trichrome.

RESULTS

No deaths were caused by the procedure, and none of the rabbits developed bleeding or haematoma after surgery. Cavernosography at 2 weeks showed contrast medium leaking from the site of the Surgicel, but at 6 and 12 weeks all rabbits had a straight erection with patent corpora and no evidence of narrowing or venous leak. Histopathological evaluation revealed evidence of the remnants of Surgicel surrounded by acute inflammatory cell infiltrate with early neovascularization at 2 weeks. At 6 and 12 weeks, there was complete normal regeneration of the tunica albuginea with no foreign-body reaction.

CONCLUSIONS

In this pilot study, Surgicel had a clear haemostatic effect when covering a defect in the tunica albuginea. Moreover, normal tunica albuginea regenerated by 6 weeks and was maintained at 12 weeks. These results suggest that Surgicel might be considered a safe and effective grafting material for tunica albuginea substitution, including the surgical management of penile chordee.

The lord of the ring: mandatory role of the kidney in drug therapy of hypertension

Strong evidence supports the idea that total peripheral resistance (TPR) is increased in all forms of human and experimental hypertension. Although the etiological participation of TPR in the origin and long-term maintenance of hypertension has been extensively debated, it now seems clear that the renal, nonadaptive, infinite gain-working, pressure-sensitive natriuresis and diuresis is the main mechanism of blood pressure control in the long term. The tissue, cellular, biochemical, and genetic sensors and executors of this process have not been fully identified yet, but the role of the renal medulla has gained growing attention as the physiopathological scenario in which the key regulatory elements reside. Specifically, the functionality of the renomedullary vasculature seems to be highly responsible for blood pressure control. The vasculature of the renal medulla becomes a new and more specific target for the therapeutic intervention of hypertension. Recent data on the effect of baroreceptor-controlled renal sympathetic activity on the long-term regulation of blood pressure are integrated. The renomedullary effects of the main antihypertensive drugs are discussed, and new perspectives for the therapeutic intervention of hypertension are outlined. Comparison of the genetic program of the renal medulla before and after the development of hypertension in spontaneously hypertensive and experimentally induced animal models might provide a mechanism for identifying the key genes that become activated or suppressed in the development of high blood pressure. These genes, their encoded proteins, or other elements related to their signalling and genetic pathways might serve as new and more specific targets for the pharmacological treatment of abnormally elevated blood pressure. Besides, proteins specifically located to the luminal side of the renomedullary vascular endothelium may serve as potential targets for site-directed drug and gene therapy.