[Efficiency and safety of microsurgical cluster ligation of the spermatic vein].

OBJECTIVE: To study the effect and safety of microscopic varicocele cluster ligation (MVCL). METHODS: We selected 28 patients undergoing bilateral microscopic spermatic vein ligation in Xuzhou Central Hospital from July 2021 to June 2022. Using the computerized randomization method, we performed MVCL or microscopic varicocele ligation (MVL) for the right or the left spermatic cord, respectively. We recorded the operation time, intraoperative blood loss, the numbers of the spermatic veins ligated and the arteries and lymphatic vessels preserved in each surgical side. A surgeon unaware of the surgical approach on the operative side collected the Visual Analogue Scale (VAS) pain scores, nodular foreign body sensation, relief of scrotal cramps, complications, and long-term recurrence from the patients. RESULTS: Compared with the MVL group, the MVCL group showed significantly shorter time for spermatic vein ligation (ï¼»56.21±13.96ï¼½ vs ï¼»31.43±10.13ï¼½ min, P<0.01), lower VAS scores on the 1st postoperative day (P <0.05) and a lower incidence of intra-scrotal nodular foreign body sensation in the 1st postoperative month (P <0.05). There were no statistically significant differences in the intraoperative blood loss, numbers of spermatic veins ligated and arteries and lymphatic vessels preserved, VAS scores at 3 and 7 postoperative days, incidence of complications and long-term recurrence between the two groups (P >0.05). CONCLUSION: MVCL is superior to MVL in reducing the time of spermatic vein ligation and improving the efficiency, efficacy and safety of the procedure, and therefore worthy of clinical promotion.

Efficient synthesis of secondary amines by reductive amination of curdlan Staudinger ylides.

Staudinger-related reactions between azides and phosphines are important in organic chemistry due to their chemoselectivity, high efficiency, and mild reaction conditions. Staudinger reduction of azides affords highly reactive iminophosphorane ylides; the reactivity of the negatively charged ylide nitrogen atom has not previously been fully explored in polysaccharide chemistry. Curdlan, a natural, biocompatible, and bioactive ß-1,3-glucan with low toxicity, has remarkable potential in biomedical and pharmaceutical applications. Herein we describe a new method for preparation of regioselectively iminated/aminated curdlan derivatives via a Staudinger ylide. 6-Azido-6-deoxy-2,4-di-O-acyl-curdlan was treated with triphenylphosphine to generate the highly nucleophilic iminophosphorane intermediate which afforded: i) 6-imino curdlans by reaction with several aromatic aldehydes, and ii) 6-monoalkylamino curdlans by reductive amination using these aldehydes and NaBH3CN. This new chemistry combined with our previous results makes available valuable primary, secondary, and tertiary amines, quaternary ammonio derivatives, and amides, all with complete C-6 regioselectivity for the N-substitution.

Multifunctional Cellulolytic Enzymes Outperform Processive Fungal Cellulases for Coproduction of Nanocellulose and Biofuels.

Producing fuels, chemicals, and materials from renewable resources to meet societal demands remains an important step in the transition to a sustainable, clean energy economy. The use of cellulolytic enzymes for the production of nanocellulose enables the coproduction of sugars for biofuels production in a format that is largely compatible with the process design employed by modern lignocellulosic (second generation) biorefineries. However, yields of enzymatically produced nanocellulose are typically much lower than those achieved by mineral acid production methods. In this study, we compare the capacity for coproduction of nanocellulose and fermentable sugars using two vastly different cellulase systems: the classical "free enzyme" system of the saprophytic fungus, Trichoderma reesei (T. reesei) and the complexed, multifunctional enzymes produced by the hot springs resident, Caldicellulosiruptor bescii (C. bescii). We demonstrate by comparative digestions that the C. bescii system outperforms the fungal enzyme system in terms of total cellulose conversion, sugar production, and nanocellulose production. In addition, we show by multimodal imaging and dynamic light scattering that the nanocellulose produced by the C. bescii cellulase system is substantially more uniform than that produced by the T. reesei system. These disparities in the yields and characteristics of the nanocellulose produced by these disparate systems can be attributed to the dramatic differences in the mechanisms of action of the dominant enzymes in each system.

Regioselective synthesis of cationic 6-deoxy-6-(N,N,N-trialkylammonio)curdlan derivatives.

Curdlan, a bioactive ß-1,3-glucan, is of intense interest for pharmaceutical and biomedical applications. Cationic derivatives of curdlan and other polysaccharides are especially attractive for their potential to interact in controlled fashion with proteins, among many other possible applications, but relatively few methods exist for their synthesis. Herein we report a regioselective method for preparation of cationic, water-soluble 6-(N,N,N-trialkylammonio)-6-deoxycurdlan salts by reaction of 6-bromo-6-deoxycurdlan and its 2,4-O-diesters with trialkylamines. Dimethyl sulfoxide was identified as the optimal solvent for this nucleophilic displacement to produce cationic curdlan derivatives (80 °C, 24h), providing maximum degree of triethylammonium substitution (DS) of 0.89, exclusively at the C-6 position. 6-Bromo-6-deoxycurdlan was also reacted with heterocyclic amines such as pyridine and imidazole, providing ammonium-substituted curdlan derivatives with substantial DS (0.66 and 0.86, respectively). The new combination of regioselective Furuhata bromination and bromine displacement under optimized conditions with tertiary amines provides access to quaternized curdlan derivatives that possess high, permanent positive charge and are readily water-soluble, properties that indicate potential application promise including for mucoadhesion, permeation enhancement, and delivery of genes and anionic drugs. Regioselectivity and DS of those curdlan ammonium derivatives were quantified by means of (1)H NMR, (13)C NMR and FTIR spectroscopic methods and by elemental analysis.

Water-soluble aminocurdlan derivatives by chemoselective azide reduction using NaBH4.

Water-solubility can often enhance the utility of polysaccharide derivatives, for example in pharmaceutical and biomedical applications. Synthesis of water-soluble aminopolysaccharides, particularly those bearing other sensitive functional groups, can be a challenging endeavor. Curdlan is a bioactive ß-1,3-glucan with considerable promise for biomedical applications. Aminocurdlans are intriguing target molecules for study of, for example, their interactions with the proteins that form tight junctions between enterocytes. Herein we report the preparation of two water-soluble 6-aminocurdlans starting from 6-bromo-6-deoxycurdlan. The 6-bromide was first displaced by nucleophilic substitution with sodium azide in dimethyl sulfoxide. The O-2 groups were acylated with hydrophilic oligo (ethylene oxide) esters, so as to enhance aqueous solubility. The resultant 6-azido-6-deoxy-2,4-di-O-trioxadecanoylcurdlan was then treated with excess sodium borohydride to reduce the azide; unexpectedly, the water-soluble product proved to be the amide, 6-trioxadecanamido-6-deoxycurdlan. Regioselectivity and degree of substitution (DS) of those derivatives were characterized by means of (1)H NMR, (13)C NMR and FTIR-spectroscopy, elemental analysis, and titration. Alternatively, direct borohydride reduction of the parent 6-azido-6-deoxycurdlan afforded 6-amino-6-deoxycurdlan that was also water-soluble.

Glycan ester deacylation by TBAOH or TBAF: regioselectivity vs. polysaccharide structure.

Tetrabutylammonium fluoride (TBAF) and tetrabutylammonium hydroxide (TBAOH) have been found to mediate regioselective deacylation of cellulose esters, with unexpected selectivity for removal of acyl groups at the more hindered secondary O-2/3 positions. This simple, efficient, one-step process triggers our investigation of TBAF/TBAOH deacylation on other glycan (amylose, curdlan, dextran, pullulan and glucomannan) esters to examine the generality of this reaction and the impact of glucan and glucomannan structure on deacylation regioselectivity. Remarkably regioselective O-2/3 deacylation was observed with amylose triesters, while moderately regioselective O-2/4 deacylation of curdlan triester occurred. No regioselectivity was observed with dextran triester, as predicted due to the lack of primary OH groups. We observed deacylation of pullulan and glucomannan triesters, but due to the complexity of the partially substituted products have not yet been able to determine the deacylation regioselectivity for these glycan esters.

Synthesis of curdlan derivatives regioselectively modified at C-6: O-(N)-Acylated 6-amino-6-deoxycurdlan.

There has been growing interest in aminopolysaccharide synthesis over the last two decades due to the critical natural functions of aminopolysaccharides, and their potential in biomedical applications. Regioselective introduction of amino groups into polysaccharide backbones is a challenge. Natural curdlan is a linear ß-(1→3)-glucan that is of interest both for its physical properties and its biomedical applications. Aminated curdlan derivatives were synthesized in three steps. First, curdlan was regioselectively brominated at the C-6 position in lithium bromide-N,N-dimethylacetamide (DMAc/LiBr). Second, the bromide of the product 6-bromo-6-deoxycurdlan was displaced by nucleophilic substitution with sodium azide (NaN3) in dimethyl sulfoxide (DMSO). Third, O-acylated 6-amido-6-deoxycurdlan was produced by a one-pot method. 6-Azido-6-deoxycurdlan was subjected to Staudinger reduction, followed by reaction in situ with excess carboxylic anhydride, without isolation of the 6-amino-6-deoxycurdlan intermediate. Regioselectivity and degree of substitution (DS) of these derivatives were confirmed by (1)H and (13)C NMR spectroscopy, FTIR spectroscopy, and elemental analysis.

Properties, chemistry, and applications of the bioactive polysaccharide curdlan.

Curdlan is a bacterial polysaccharide that has been of significant recent interest due to its interesting and valuable rheological properties and its inherent bioactivity. The simple (1→3)-ß-glucan homopolymeric, unbranched structure of curdlan is conducive to enhanced solubility relative to many other abundant natural polysaccharides, thus, providing alternatives for processing the polymer into desired shapes and formulations. At the same time, this relatively good solubility enables chemical modification under mild conditions, leading to a growing body of literature on derivative chemistry, structure-property relationships, and the potential for regioselective modification. Structure, properties, biosynthesis, modification chemistries, and key applications are the foci for this review of the curdlan literature.