Polyvinylpyrrolidone hydrogel coating for ureteral stent: Safety and performance evaluation.

BACKGROUND: Ureteral stents are commonly used in urology. However, complications such as encrustation and infection on the surface of the stent, and injury to the ureteral mucosa can occur after implantation, causing discomfort for patients. OBJECTIVE: We intend to confirm the biosafety of polyvinylpyrrolidone (PVP) hydrophilic coating and its lubrication properties for surface modification of ureteral stents to reduce friction and improve patient comfort. METHODS: Based on our previous studies, we have developed a PVP hydrophilic coating for surface modification of ureteral stents. We firstly investigated the cytotoxicity, intradermal irritation, delayed type hypersensitivity, and acute systemic reactions of stent coating extracts. We further characterized the break strength, retention strength, and dynamic friction of the stent. RESULTS: The cell survival rate of all experimental groups was greater than 70%. No hypersensitivity reaction, systemic toxicity reaction, or obvious intradermal reaction were observed. The above results indicate that the test results of the modified stent meet the requirements of ISO 10993-5: 2009 (Cytotoxicity); ISO 10993-10:2021 (Sensitization and Irritation); ISO 10993-11:2017 (Acute Systemic Toxicity). After soaking in artificial urine for an extended period, there was no obvious change in its super-slip performance. CONCLUSION: Our results confirm the safety and lubrication characteristics of PVP hydrophilic coating for ureteral stent surface modification. The performance of this coating has the potential to reduce complications after stent implantation, thereby improving patient comfort, reducing medical burden, and has a good clinical application prospect.

National debt management and business sustainability in Africa's largest economy: A focus on the private sector.

In many developing economies, high and increasing public debt profile constitutes an essential means of financial risk. An appropriate debt management is germane for survival of business and good international reputation though its effect on private sector credit mobilization had been seldomly investigated. This study seeks to know whether strategic debt management approach exacts a significant effect on the Nigerian private sector and Africa at large resulting to higher credit availability for sustainable enterprise establishment. The study used a time-series observation spanning from 1981-2021. The method of data analysis employed the unit root test for stationarity. Johansen cointegration and vector error correction approach. The result of the unit root test indicates the series were all stationary after first difference and thus were integrated of order1. The Johansen cointegration test support the existence of a cointegrating series between the private credit and its determinants. More empirical evidence from the study shows that proper debt management and increase revenue generation through net taxes on products accounted for 0.93 and 1.32% increase in private sector credit mobilization, while total external debt stock was responsible for a significant negative influence of 0.60% on private sector credit mobilization. The study recommends that the government should always be proactive in their strategic and innovative approach to debt management, revenue generation and sources of funds. This will help not only to avoid crowding out of the private sector but will enhance adequate credit mobilization for effective operations of the private sector.