NO-Releasing Nanoparticles Ameliorate Detrusor Overactivity in Transgenic Sickle Cell Mice via Restored NO/ROCK Signaling

Asymmetric Dimethylarginine Enables Depolarizing Spikes and Vasospasm in Mesenteric and Coronary Resistance Arteries

BACKGROUND

Increased vasoreactivity due to reduced endothelial NO bioavailability is an underlying feature of cardiovascular disease, including hypertension. In small resistance arteries, declining NO enhances vascular smooth muscle (VSM) reactivity partly by enabling rapid depolarizing Ca2+-based spikes that underlie vasospasm. The endogenous NO synthase inhibitor asymmetric dimethylarginine (ADMA) is metabolized by DDAH1 (dimethylarginine dimethylaminohydrolase 1) and elevated in cardiovascular disease. We hypothesized ADMA might enable VSM spikes and vasospasm by reducing NO bioavailability, which is opposed by DDAH1 activity and L-arginine.

METHODS

Rat isolated small mesenteric arteries and myogenic rat-isolated intraseptal coronary arteries (RCA) were studied using myography, VSM intracellular recording, Ca2+ imaging, and DDAH1 immunolabeling. Exogenous ADMA was used to inhibit NO synthase and a selective DDAH1 inhibitor, NG-(2-methoxyethyl) arginine, to assess the functional impact of ADMA metabolism.

RESULTS

ADMA enhanced rat-isolated small mesenteric arteries vasoreactivity to the α1-adrenoceptor agonist, phenylephrine by enabling T-type voltage-gated calcium channel-dependent depolarizing spikes. However, some endothelium-dependent NO-vasorelaxation remained, which was sensitive to DDAH1-inhibition with NG-(2-methoxyethyl) arginine. In myogenically active RCA, ADMA alone stimulated depolarizing Ca2+ spikes and marked vasoconstriction, while NO vasorelaxation was abolished. DDAH1 expression was greater in rat-isolated small mesenteric arteries endothelium compared with RCA, but low in VSM of both arteries. L-arginine prevented depolarizing spikes and protected NO-vasorelaxation in rat-isolated small mesenteric artery and RCA.

CONCLUSIONS

ADMA increases VSM electrical excitability enhancing vasoreactivity. Endothelial DDAH1 reduces this effect, and low levels of DDAH1 in RCAs may render them susceptible to endothelial dysfunction contributing to vasospasm, changes opposed by L-arginine.

Enuresis and overactive bladder in sickle cell patients: a narrative review of the literature

OBJECTIVE

The aim of this review is to clarify the prevalence, pathophysiology and clinical presentation of enuresis and overactive bladder in sickle cell patients.

MATERIALS AND METHODS

This narrative review of the literature was conducted in March 2022 by running a search in PubMed, Embase, Scopus and Cochrane databases without publication date limitation, using the following keywords: enuresis or nocturia or overactive bladder or urinary incontinence or bedwetting and sickle cell.

RESULTS

Eight cross-sectional studies were included, six of which had a non-sickle cell control population. The prevalence of enuresis in children and adolescents with sickle cell disease ranged from 20.3 to 49.4%. It decreased with age to 2.9% in adult sickle cell patients. Enuresis in sickle cell patients has been attributed to several causes, including lack of urine concentration with nocturnal polyuria, reduced bladder capacity, nocturnal bladder hyperactivity, sleep and/or respiratory disorders are likely causes of enuresis in sickle cell patients. The prevalence of overactive bladder is three times higher in sickle cell patients than in control groups. The latter is also observed three times more frequently in men who have had prior episodes of priapism.

CONCLUSION

Enuresis and overactive bladder are common in sickle cell patients. Several mechanisms have been described to try to explain enuresis in sickle cell patients but overactive bladder seems to play a major role. Studies evaluating the efficacy of certain experimentally validated treatments must be carried out to improve the management of these complications which affect the quality of life of sickle cell patients.

A Feasibility Study to Evaluate Changes in Urinary Metabolites after OnabotulinumtoxinA Injection for Refractory Overactive Bladder

Metabolomics analysis of urine before and after overactive bladder (OAB) treatment may demonstrate a unique molecular profile, allowing predictions of responses to treatment. This feasibility study aimed to correlate changes in urinary metabolome with changes in OAB symptoms after intravesical onabotulinumtoxinA (BTX-A) injections for refractory OAB. Women 18 years or older with non-neurogenic refractory OAB were recruited to complete OAB-V8 questionnaires and submit urine samples before and after 100 units intravesical BTX-A injection. Samples were submitted to CE-TOFMS metabolomics profiling. Data were expressed as percent of change from pre-treatment and were correlated with OAB-V8 score improvement. Urinary metabolite changes in the OAB-V8 groups were compared using the Kruskal–Wallis test, and associations between metabolites and OAB-V8 scores were examined using quantile regression analysis. Of 61 urinary metabolites commonly detected before and after BTX-A, there was a statistically significant decrease in adenosine and an increase in N8-acetylspermidine and guanidinoacetic acid levels associated with OAB score improvement, suggesting that intravesical BTX-A injection modifies the urinary metabolome. These urinary metabolites could provide insight into OAB pathophysiology and help identify patients who would benefit most from chemodenervation.

Nanotechnology as a tool to advance research and treatment of non-oncologic urogenital diseases

Nanotechnology represents an expanding area of research and innovation in almost every field of science, including Medicine, where nanomaterial-based products have been developed for diagnostic and therapeutic applications. Because of their small, nanoscale size, these materials exhibit unique physical and chemical properties that differ from those of each component when considered in bulk. In Nanomedicine, there is an increasing interest in harnessing these unique properties to engineer nanocarriers for the delivery of therapeutic agents. Nano-based drug delivery platforms have many advantages over conventional drug administration routes as this technology allows for local and transdermal applications of therapeutics that can bypass the first-pass metabolism, improves drug efficacy through encapsulation of hydrophobic drugs, and allows for a sustained and controlled release of encapsulated agents. In Urology, nano-based drug delivery platforms have been extensively investigated and implemented for cancer treatment. However, there is also great potential for use of nanotechnology to treat non-oncologic urogenital diseases. We provide an update on research that is paving the way for clinical translation of nanotechnology in the areas of erectile dysfunction (ED), overactive bladder (OAB), interstitial cystitis/bladder pain syndrome (IC/BPS), and catheter-associated urinary tract infections (CAUTIs). Overall, preclinical and clinical studies have proven the utility of nanomaterials both as vehicles for transdermal and intravesical delivery of therapeutic agents and for urinary catheter formulation with antimicrobial agents to treat non-oncologic urogenital diseases. Although clinical translation will be dependent on overcoming regulatory challenges, it is inevitable before there is universal adoption of this technology to treat non-oncologic urogenital diseases.

Cavernous Nerve Injury Resulted Erectile Dysfunction and Regeneration

Erectile dysfunction (ED) is an important cause of reduced quality of life for men and their partners. Recent studies have found that cavernous nerve injury (CNI) during prostate cancer surgery and other pelvic surgery results in medically induced CNIED in more than 80% of patients. The efficacy of first- and second-line treatment options for ED is poor. A great deal of research has been devoted to exploring new methods of neuroprotection and nerve regeneration to save erectile function in patients with CNIED, especially in patients with cavernous nerve injury after prostate cancer surgery. In addition, such as neuromodulatory proteins, proimmune ligands, gene therapy, stem cell therapy, and the current cutting-edge low-energy shock wave therapy have shown advantages in basic research and limited clinical studies. In the context of today's modern medicine, these new therapeutic techniques are expected to be new tools in the treatment of cavernous nerve injury erectile dysfunction. This article presents the main causes, mechanisms, and treatment of cavernous nerve injury erectile dysfunction and combines them with new treatment strategies.

Topically delivered nitric oxide acts synergistically with an orally administered PDE5 inhibitor in eliciting an erectile response in a rat model of radical prostatectomy

Patients undergoing radical prostatectomy (RP) have a high incidence of post-operative erectile dysfunction (ED) refractory to treatment by oral phosphodiesterase-type-5-inhibitors (PDE5i). In the present studies, we investigated if a topically applied, nitric oxide microparticle delivery system (NO-MP) might act synergistically with an oral PDE5i (sildenafil) to improve erectile function outcomes in a rat model of RP.

Thirty-five Sprague–Dawley rats underwent bilateral transection of the cavernous nerve (CN) for one week. After one-week, animals were orally administered 0, 0.05 or 0.005 mg sildenafil/kg and the erectile response following topical application to the penile shaft of 250mg or 100mg NO-MP, or blank-MP, was monitored over a two-hour timeframe by recording the intracorporal pressure normalized to systemic blood pressure (ICP/BP, N=5 animals/treatment group).

Oral treatment with sildenafil by itself resulted in no observable erectile response. However, a combination of orally administered 0.05 sildenafil/kg with topical application of 250mg NO-MP, compared to 250 mg NO-MP by itself, resulted in significantly more spontaneous erections (4.6 compared to 2 erections per hour, t-test; p-value = 0.043), with a significantly faster onset for the first erectile response (11 compared to 22 minutes; t-test, p-value = 0.041).

Our results demonstrate a synergistic effect between orally administered PDE5i and topically applied NO-MP in eliciting an erectile response. Furthermore, they suggest a potential novel therapeutic approach to treat men with ED resulting from RP, through combination therapy of a topically applied NO-MP and an orally administered PDE5i.