Publications by authors named "Igor Fokin"

4 Publications

  • Page 1 of 1

A systematic review of nerve-sparing surgery for high-risk prostate cancer.

Minerva Urol Nephrol 2021 Jun 13;73(3):283-291. Epub 2021 Jan 13.

Institute for Urology and Reproductive Health, Sechenov University, Moscow, Russia.

Introduction: We provide a systematic analysis of nerve-sparing surgery (NSS) to assess and summarize the risks and benefits of NSS in high-risk prostate cancer (PCa).

Evidence Acquisition: We have undertaken a systematic search of original articles using 3 databases: Medline/PubMed, Scopus, and Web of Science. Original articles in English containing outcomes of nerve-sparing radical prostatectomy (RP) for high-risk PCa were included. The primary outcomes were oncological results: the rate of positive surgical margins and biochemical relapse. The secondary outcomes were functional results: erectile function (EF) and urinary continence.

Evidence Synthesis: The rate of positive surgical margins differed considerably, from zero to 47%. The majority of authors found no correlation between NSS and a positive surgical margin rate. The rate of biochemical relapse ranged from 9.3% to 61%. Most of the articles lacked data on odds ratio (OR) for positive margin and biochemical relapse. The presented results showed no effect of nerve sparing (NS) on positive margin (OR=0.81, 0.6-1.09) or biochemical relapse (hazard ratio [HR]=0.93, 0.52-1.64). A strong association between NSS and potency rate was observed. Without NSS, between 0% and 42% of patients were potent, with unilateral 79-80%, with bilateral - up to 90-100%. Urinary continence was not strongly associated with NSS and was relatively good in both patients with and without NSS.

Conclusions: NSS may provide benefits for patients with urinary continence and significantly improves EF in high-risk patients. Moreover, it is not associated with an increased risk of relapse in short- and middle-term follow-up. However, the advantages of using such a surgical technique are unclear.
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http://dx.doi.org/10.23736/S0393-2249.20.04178-8DOI Listing
June 2021

Endoscopic lithotripsy with a SuperPulsed thulium-fiber laser for ureteral stones: A single-center experience.

Int J Urol 2021 03 30;28(3):261-265. Epub 2020 Nov 30.

Institute for Urology and Reproductive Health, Sechenov University, Moscow, Russia.

Objectives: To estimate the efficacy and safety of SuperPulsed thulium-fiber laser ureteral lithotripsy and to identify optimal laser settings.

Methods: Patients with solitary stones were prospectively included. Lithotripsy was performed with a SuperPulsed thulium-fiber laser (NTO IRE-Polus, Fryazino, Russia) using a rigid ureteroscope 7.5 Ch (Richard Wolf, Knittlingen, Germany). We analyzed the efficacy of lithotripsy by measuring total energy required for stone disintegration, "laser-on" time, ablation speed, ablation efficacy, and energy consumption. Stone retropulsion and visibility were assessed using a three-point Likert scale. Complications were assessed using the Clavien-Dindo classification system.

Results: A total of 149 patients were included. The mean stone density was 985 ± 360 Hounsfield units, the median (interquartile range) stone volume was 179 (94-357) mm . The median (interquartile range) total energy was 1 (0.4-2) kJ, and laser-on time 1.2 (0.5-2.7) min. The median (interquartile range) stone ablation speed was 140 (80-279) mm /min, energy for ablation of 1 mm was 5.6 (3-9.9) J/mm and energy consumption was 0.9 (0.6-1) J/min. A correlation was found between retropulsion and the energy used (r = 0.5, P < 0.001). Multivariable analysis showed energy to be a predictor of increased retropulsion (odds ratio 65.7, 95% confidence interval 1.6-2774.1; P = 0.028). No predictors for worse visibility were identified.

Conclusion: The SuperPulsed thulium-fiber laser provides effective and safe lithotripsy during ureteroscopy regardless of stone density. Fiber diameter and laser frequency do not influence visibility or safety. Optimal laser settings are 0.5 J × 30 Hz for fragmentation and 0.15 J × 100 Hz for dusting.
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http://dx.doi.org/10.1111/iju.14443DOI Listing
March 2021

Chemoselective Electrochemical Hydrogenation of Ketones and Aldehydes with a Well-Defined Base-Metal Catalyst.

Chemistry 2020 Nov 4;26(62):14137-14143. Epub 2020 Oct 4.

Institut für Anorganische Chemie, Universität Göttingen, Tammannstr. 4, 37077, Göttingen, Germany.

Hydrogenation reactions are fundamental functional group transformations in chemical synthesis. Here, we introduce an electrochemical method for the hydrogenation of ketones and aldehydes by in situ formation of a Mn-H species. We utilise protons and electric current as surrogate for H and a base-metal complex to form selectively the alcohols. The method is chemoselective for the hydrogenation of C=O bonds over C=C bonds. Mechanistic studies revealed initial 3 e reduction of the catalyst forming the steady state species [Mn (H L)(CO) ] . Subsequently, we assume protonation, reduction and internal proton shift forming the hydride species. Finally, the transfer of the hydride and a proton to the ketone yields the alcohol and the steady state species is regenerated via reduction. The interplay of two manganese centres and the internal proton relay represent the key features for ketone and aldehyde reduction as the respective mononuclear complex and the complex without the proton relay are barely active.
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http://dx.doi.org/10.1002/chem.202002075DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7702145PMC
November 2020

The Impact of a Proton Relay in Binuclear α-Diimine-Mn(CO) Complexes on the CO Reduction Catalysis.

Inorg Chem 2019 Aug 3;58(16):10444-10453. Epub 2019 Jul 3.

Universität Göttingen , Institut für Anorganische Chemie , Tammannstr. 4 , 37077 Göttingen , Germany.

Herein, we describe the redox chemistry of bi- and mononuclear α-diimine-Mn(CO) complexes with an internal proton source in close proximity to the metal centers and their catalytic activity in the electrochemically driven CO reduction reactions. In order to address the impact of the two metal sites and of the proton source, we investigate a binuclear complex with phenol moiety, , a binuclear Mn complex with methoxyphenol unit instead, , and the mononuclear analogue with a phenol unit, . Spectroelectrochemical investigation of the complexes in dmf under a nitrogen atmosphere indicates that and undergo a reductive H formation forming [Mn(HL)(CO)Br] and [Mn(HL)(CO)], respectively, which is redox neutral for the complex and equivalent to a deprotonation of the phenol unit. The reaction likely proceeds via internal proton transfer from the phenol moiety to the reduced metal center forming a Mn-H species. dimerizes during reduction, forming [Mn(L)(CO)], but and do not. Reduction of , , and is accompanied by bromide loss, and the final species represent [Mn(HL)(CO)], [Mn(L)(CO)], and [Mn(HL)(CO)], respectively. and are active catalysts in the electrochemical CO reduction reaction, whereas decomposes quickly under an applied potential. Thus, the second redox active unit is crucial for enhanced stability. The proton relay in alters the kinetics for the 2H/2e reduced products of CO in dmf/water mixtures. For , CO is the only product, whereas formate and CO are formed in similar amounts, 40% and 50%, respectively, in the presence of . Thus, the reaction rate for the internal proton transfer from the phenol moiety to the metal center forming the putative Mn-H species and subsequent CO insertion as well as the reaction rate of the reduced metal center with CO forming CO are similar. The overpotential with regard to the standard redox potential of CO to CO and the observed overall rate constant for catalysis at scan rates of 0.1 V s are higher with than with , that is, the OH group is beneficial for catalysis due to the internal proton transfer.
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http://dx.doi.org/10.1021/acs.inorgchem.9b00992DOI Listing
August 2019
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