Nutritional Status and Quality of Life in Patients with Oral Squamous Cell Carcinoma Before and After Surgical Oncological Treatment: A Single-Center Retrospective Study.

BACKGROUND Oral squamous cell carcinoma (OSCC) is the most common of head and neck malignancies in well-developed countries. In most cases, patients with OSCC experience a degree of nutritional status disturbances and decreased quality of life (QoL). This study aimed to compare nutritional status and QoL in 51 patients before and after surgery for OSCC. MATERIAL AND METHODS Fifty-one eligible patients with OSCC were followed during a 3-year period (2019-2022). For all patients, we determined body mass index (BMI), serum albumin (ALB), prognostic nutritional index, and nutritional risk index before and after treatment. Also, all patients completed a standardized QoL questionnaire before and after treatment. The obtained data were compared between the groups by using the t test and multivariate Cox regression. RESULTS The values of BMI and NRI were statistically significantly different between the preoperative and postoperative measurements (24.1 kg/m² vs 21.1 kg/m², and 103 vs 100.1, respectively, P=0.001), while values of ALB and prognostic nutritional index did not differ significantly (41.35 g/L vs 39.1 g/L, and 48.5 vs 46.2, respectively). Dysphagia (P=0.03) and chewing problems (P=0.04) were found to be the 2 most important factors decreasing the QoL of patients. CONCLUSIONS Based on our results, BMI and NRI were the most sensitive parameters of nutritional status. Dysphagia and chewing problems were the 2 most important factors affecting the QoL in patients with OSCC.

One-Pot Biocatalytic Synthesis of rac-Syringaresinol from a Lignin-Derived Phenol.

The drive for a circular bioeconomy has resulted in a great demand for renewable, biobased chemicals. We present a one-pot biocatalytic cascade reaction for the production of racemic syringaresinol, a lignan with applications as a nutraceutical and in polymer chemistry. The process consumes dihydrosinapyl alcohol, which can be produced renewably from the lignocellulosic material. To achieve this, a variant of eugenol oxidase was engineered for the oxidation of dihydrosinapyl alcohol into sinapyl alcohol with good conversion and chemoselectivity. The crystal structure of the engineered oxidase revealed the molecular basis of the influence of the mutations on the chemoselectivity of the oxidation of dihydrosinapyl alcohol. By using horseradish peroxidase, the subsequent oxidative dimerization of sinapyl alcohol into syringaresinol was achieved. Conditions for the one-pot, two-enzyme synthesis were optimized, and a high yield of syringaresinol was achieved by cascading the oxidase and peroxidase steps in a stepwise fashion. This study demonstrates the efficient production of syringaresinol from a compound that can be renewed by reductive catalytic fractionation of lignocellulose, providing a biocatalytic route for generating a valuable compound from lignin.

Pulmonary Valve Endocarditis during and beyond Euro ENDO Registry: A Single Center Case Series.

Background: Pulmonary valve infective endocarditis (PVIE) is a rare form of infective endocarditis (IE) and is associated with high mortality and severe complications. Guidelines for treatment of this form of IE are scarce and based on general recommendations. We report a case series of PVE. Detailed Case Description: Case 1-A 36-year-old female with congenital pulmonary artery stenosis, dyspnea and leg edema symptoms for 2 months. Blood cultures yielded Staphylococcus spp. and Corynebacterium sp., and echocardiography revealed multiple floating vegetation at the pulmonic valve and surrounding structures. The clinical course was complicated with sepsis and multi-organ failure. Urgent surgery with pulmonary homograft implantation resulted in successful five-year outcome. Case 2-In a 38-year-old male with previous tetralogy of Fallot correction and symptoms of fatigue, fever, myalgia, and photophobia, echocardiography was suggestive of PVIE. The clinical course was complicated with septic shock, multi-organ failure, ischemic stroke with hemorrhagic transformation and death on the 12th day of hospitalization. Case 3-A 41-year-old male without previous medical history was hospitalized due to prolonged fatigue, fever, dyspnea, and leg edema. He was diagnosed with multi-valve infective endocarditis, affecting the aortic, tricuspid, and pulmonary valve. Acute heart failure and hemodynamic instability indicated urgent surgery with aortic valve replacement and reconstruction of the tricuspid and pulmonary valves. At four-year follow up he was doing well. Conclusion: Symptoms in PVIE may be versatile, and diagnosis is often delayed. High level of suspicion, early recognition, and echocardiography are cornerstones in diagnostics. Despite the standpoint that medical therapy is first-line, the role of surgery needs to be advocated in particular cases.

Simultaneous Double-Vessel Coronary Thrombosis with Sudden Cardiac Arrest as the First Manifestation of COVID-19.

The relationship between coronavirus disease 2019 (COVID-19) and myocardial injury was established at the onset of the COVID-19 pandemic. An increase in the incidence of out-of-hospital cardiac arrest was also observed. This case report aims to point to the prothrombotic and proinflammatory nature of coronavirus infection, leading to simultaneous coronary vessel thrombosis and subsequently to out-of-hospital cardiac arrest. During the COVID-19 pandemic, a 46-year-old male patient with no comorbidities suffered out-of-hospital cardiac arrest (OHCA) with ventricular fibrillation as the first recorded rhythm. The applied cardiopulmonary resuscitation (CPR) measures initiated by bystanders and continued by emergency medical service (EMS) resulted in the return of spontaneous circulation. The stabilized patient was transferred to the tertiary university center. Electrocardiogram (ECG) revealed "lambda-like" ST-segment elevation in DI and aVL leads, necessitating an immediate coronary angiography, which demonstrated simultaneous occlusion of the left anterior descending (LAD) and right coronary artery (RCA). Primary percutaneous coronary intervention (PCI) with the implantation of one drug-eluting stent (DES) in LAD and two DES in RCA was done. Due to the presence of cardiogenic shock (SCAI C), an intra-aortic balloon pump (IABP) was implanted during the procedure, and due to the comatose state and shockable cardiac arrest, targeted temperature management was initiated. The baseline chest X-ray revealed bilateral interstitial infiltrates, followed by increased proinflammatory markers and a positive polymerase chain reaction (PCR) test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) demasking underlying COVID-19-related pneumonia. Within the following 48 h, the patient was hemodynamically stable, which enabled weaning from IABP and vasopressor discontinuation. However, due to the worsening of COVID-19 pneumonia, prolonged mechanical ventilation, together with antibiotics and other supportive measures, was needed. The applied therapy resulted in clinical improvement, and the patient was extubated and finally discharged on Day 26, with no neurological sequelae and with mildly reduced left ventricle ejection fraction.

Structure- and computational-aided engineering of an oxidase to produce isoeugenol from a lignin-derived compound.

Various 4-alkylphenols can be easily obtained through reductive catalytic fractionation of lignocellulosic biomass. Selective dehydrogenation of 4-n-propylguaiacol results in the formation of isoeugenol, a valuable flavor and fragrance molecule and versatile precursor compound. Here we present the engineering of a bacterial eugenol oxidase to catalyze this reaction. Five mutations, identified from computational predictions, are first introduced to render the enzyme more thermostable. Other mutations are then added and analyzed to enhance chemoselectivity and activity. Structural insight demonstrates that the slow catalytic activity of an otherwise promising enzyme variant is due the formation of a slowly-decaying covalent substrate-flavin cofactor adduct that can be remedied by targeted residue changes. The final engineered variant comprises eight mutations, is thermostable, displays good activity and acts as a highly chemoselective 4-n-propylguaiacol oxidase. We lastly use our engineered biocatalyst in an illustrative preparative reaction at gram-scale. Our findings show that a natural enzyme can be redesigned into a tailored biocatalyst capable of valorizing lignin-based monophenols.

Chemoenzymatic Synthesis of the Most Pleasant Stereoisomer of Jessemal.

We describe the asymmetric synthesis of the most pleasant enantiomer of Jessemal fragrance. The key steps are (i) the one-pot reduction of an α-chloro-tetrasubstituted cyclohexenone to give the chlorohydrin, catalyzed by two stereoselective redox enzymes (an ene-reductase and an alcohol dehydrogenase); (ii) the regioselective epoxide ring-opening with organocuprate or organolithium nucleophiles. Density functional theory calculations together with the Curtin-Hammett principle allowed the rationalization of the regioselectivity.

Introducing an Artificial Deazaflavin Cofactor in Escherichia coli and Saccharomyces cerevisiae.

Deazaflavin-dependent whole-cell conversions in well-studied and industrially relevant microorganisms such as Escherichia coli and Saccharomyces cerevisiae have high potential for the biocatalytic production of valuable compounds. The artificial deazaflavin FOP (FO-5'-phosphate) can functionally substitute the natural deazaflavin F420 and can be synthesized in fewer steps, offering a solution to the limited availability of the latter due to its complex (bio)synthesis. Herein we set out to produce FOP in vivo as a scalable FOP production method and as a means for FOP-mediated whole-cell conversions. Heterologous expression of the riboflavin kinase from Schizosaccharomyces pombe enabled in vivo phosphorylation of FO, which was supplied by either organic synthesis ex vivo, or by a coexpressed FO synthase in vivo, producing FOP in E. coli as well as in S. cerevisiae. Through combined approaches of enzyme engineering as well as optimization of expression systems and growth media, we further improved the in vivo FOP production in both organisms. The improved FOP production yield in E. coli is comparable to the F420 yield of native F420-producing organisms such as Mycobacterium smegmatis, but the former can be achieved in a significantly shorter time frame. Our E. coli expression system has an estimated production rate of 0.078 µmol L-1 h-1 and results in an intracellular FOP concentration of about 40 µM, which is high enough to support catalysis. In fact, we demonstrate the successful FOP-mediated whole-cell conversion of ketoisophorone using E. coli cells. In S. cerevisiae, in vivo FOP production by SpRFK using supplied FO was improved through media optimization and enzyme engineering. Through structure-guided enzyme engineering, a SpRFK variant with 7-fold increased catalytic efficiency compared to the wild type was discovered. By using this variant in optimized media conditions, FOP production yield in S. cerevisiae was 20-fold increased compared to the very low initial yield of 0.24 ± 0.04 nmol per g dry biomass. The results show that bacterial and eukaryotic hosts can be engineered to produce the functional deazaflavin cofactor mimic FOP.

Discovery, Biocatalytic Exploration and Structural Analysis of a 4-Ethylphenol Oxidase from Gulosibacter chungangensis.

The vanillyl-alcohol oxidase (VAO) family is a rich source of biocatalysts for the oxidative bioconversion of phenolic compounds. Through genome mining and sequence comparisons, we found that several family members lack a generally conserved catalytic aspartate. This finding led us to study a VAO-homolog featuring a glutamate residue in place of the common aspartate. This 4-ethylphenol oxidase from Gulosibacter chungangensis (Gc4EO) shares 42 % sequence identity with VAO from Penicillium simplicissimum, contains the same 8α-N3 -histidyl-bound FAD and uses oxygen as electron acceptor. However, Gc4EO features a distinct substrate scope and product specificity as it is primarily effective in the dehydrogenation of para-substituted phenols with little generation of hydroxylated products. The three-dimensional structure shows that the characteristic glutamate side chain creates a closely packed environment that may limit water accessibility and thereby protect from hydroxylation. With its high thermal stability, well defined structural properties and high expression yields, Gc4EO may become a catalyst of choice for the specific dehydrogenation of phenolic compounds bearing small substituents.

Facile Stereoselective Reduction of Prochiral Ketones by using an F420 -dependent Alcohol Dehydrogenase.

Effective procedures for the synthesis of optically pure alcohols are highly valuable. A commonly employed method involves the biocatalytic reduction of prochiral ketones. This is typically achieved by using nicotinamide cofactor-dependent reductases. In this work, we demonstrate that a rather unexplored class of enzymes can also be used for this. We used an F420 -dependent alcohol dehydrogenase (ADF) from Methanoculleus thermophilicus that was found to reduce various ketones to enantiopure alcohols. The respective (S) alcohols were obtained in excellent enantiopurity (>99 % ee). Furthermore, we discovered that the deazaflavoenzyme can be used as a self-sufficient system by merely using a sacrificial cosubstrate (isopropanol) and a catalytic amount of cofactor F420 or the unnatural cofactor FOP to achieve full conversion. This study reveals that deazaflavoenzymes complement the biocatalytic toolbox for enantioselective ketone reductions.

Substrate binding tunes the reactivity of hispidin 3-hydroxylase, a flavoprotein monooxygenase involved in fungal bioluminescence.

Fungal bioluminescence was recently shown to depend on a unique oxygen-dependent system of several enzymes. However, the identities of the enzymes did not reveal the full biochemical details of this process, as the enzymes do not bear resemblance to those of other luminescence systems, and thus the properties of the enzymes involved in this fascinating process are still unknown. Here, we describe the characterization of the penultimate enzyme in the pathway, hispidin 3-hydroxylase, from the luminescent fungus Mycena chlorophos (McH3H), which catalyzes the conversion of hispidin to 3-hydroxyhispidin. 3-Hydroxyhispidin acts as a luciferin substrate in luminescent fungi. McH3H was heterologously expressed in Escherichia coli and purified by affinity chromatography with a yield of 100 mg/liter. McH3H was found to be a single component monomeric NAD(P)H-dependent FAD-containing monooxygenase having a preference for NADPH. Through site-directed mutagenesis, based on a modeled structure, mutant enzymes were created that are more efficient with NADH. Except for identifying the residues that tune cofactor specificity, these engineered variants may also help in developing new hispidin-based bioluminescence applications. We confirmed that addition of hispidin to McH3H led to the formation of 3-hydroxyhispidin as sole aromatic product. Rapid kinetic analysis revealed that reduction of the flavin cofactor by NADPH is boosted by hispidin binding by nearly 100-fold. Similar to other class A flavoprotein hydroxylases, McH3H did not form a stable hydroperoxyflavin intermediate. These data suggest a mechanism by which the hydroxylase is tuned for converting hispidin into the fungal luciferin.

Approaching boiling point stability of an alcohol dehydrogenase through computationally-guided enzyme engineering.

Enzyme instability is an important limitation for the investigation and application of enzymes. Therefore, methods to rapidly and effectively improve enzyme stability are highly appealing. In this study we applied a computational method (FRESCO) to guide the engineering of an alcohol dehydrogenase. Of the 177 selected mutations, 25 mutations brought about a significant increase in apparent melting temperature (ΔTm ≥ +3 °C). By combining mutations, a 10-fold mutant was generated with a Tm of 94 °C (+51 °C relative to wild type), almost reaching water's boiling point, and the highest increase with FRESCO to date. The 10-fold mutant's structure was elucidated, which enabled the identification of an activity-impairing mutation. After reverting this mutation, the enzyme showed no loss in activity compared to wild type, while displaying a Tm of 88 °C (+45 °C relative to wild type). This work demonstrates the value of enzyme stabilization through computational library design.

Computational Design of Enantiocomplementary Epoxide Hydrolases for Asymmetric Synthesis of Aliphatic and Aromatic Diols.

The use of enzymes in preparative biocatalysis often requires tailoring enzyme selectivity by protein engineering. Herein we explore the use of computational library design and molecular dynamics simulations to create variants of limonene epoxide hydrolase that produce enantiomeric diols from meso-epoxides. Three substrates of different sizes were targeted: cis-2,3-butene oxide, cyclopentene oxide, and cis-stilbene oxide. Most of the 28 designs tested were active and showed the predicted enantioselectivity. Excellent enantioselectivities were obtained for the bulky substrate cis-stilbene oxide, and enantiocomplementary mutants produced (S,S)- and (R,R)-stilbene diol with >97 % enantiomeric excess. An (R,R)-selective mutant was used to prepare (R,R)-stilbene diol with high enantiopurity (98 % conversion into diol, >99 % ee). Some variants displayed higher catalytic rates (kcat ) than the original enzyme, but in most cases KM values increased as well. The results demonstrate the feasibility of computational design and screening to engineer enantioselective epoxide hydrolase variants with very limited laboratory screening.

Production of Hydroxy Acids: Selective Double Oxidation of Diols by Flavoprotein Alcohol Oxidase.

Flavoprotein oxidases can catalyze oxidations of alcohols and amines by merely using molecular oxygen as the oxidant, making this class of enzymes appealing for biocatalysis. The FAD-containing (FAD=flavin adenine dinucleotide) alcohol oxidase from P. chrysosporium facilitated double and triple oxidations for a range of aliphatic diols. Interestingly, depending on the diol substrate, these reactions result in formation of either lactones or hydroxy acids. For example, diethylene glycol could be selectively and fully converted into 2-(2-hydroxyethoxy)acetic acid. Such a facile cofactor-independent biocatalytic route towards hydroxy acids opens up new avenues for the preparation of polyester building blocks.

Enantioselective Synthesis of the Platensimycin Core by Silver(I)-Promoted Cyclization of Δ6 -α-Iodoketone.

A chiral-pool-based synthesis of the platensimycin core was achieved using (S)-lactic acid as an inexpensive starting material. The cyclohexenone ring was closed in a Mukaiyama-Michael domino sequence, while the quaternary stereocenter was created by a highly stereoselective decarboxylative allylation. The spirobicyclic skeleton was constructed by a RCM reaction. A new silver(I)-promoted cyclization reaction of Δ6 - and Δ7 -α-iodoketones was developed and applied for the pivotal carbon-carbon bond formation. The scope and limitations of this methodology are also presented.

Exploring the Selective Demethylation of Aryl Methyl Ethers with a Pseudomonas Rieske Monooxygenase.

Biocatalytic dealkylation of aryl methyl ethers is an attractive reaction for valorization of lignin components, as well as for deprotection of hydroxy functionalities in synthetic chemistry. We explored the demethylation of various aryl methyl ethers by using an oxidative demethylase from Pseudomonas sp. HR199. The Rieske monooxygenase VanA and its partner electron transfer protein VanB were recombinantly coexpressed in Escherichia coli and they constituted at least 25 % of the total protein content. Enzymatic transformations showed that VanB accepts NADH and NADPH as electron donors. The VanA-VanB system demethylates a number of aromatic substrates, the presence of a carboxylic acid moiety is essential, and the catalysis occurs selectively at the meta position to this carboxylic acid in the aromatic ring. The reaction is inhibited by the by-product formaldehyde. Therefore, we tested three different cascade/tandem reactions for cofactor regeneration and formaldehyde elimination; in particular, conversion was improved by addition of formaldehyde dehydrogenase and formate dehydrogenase. Finally, the biocatalyst was applied for the preparation of protocatechuic acid from vanillic acid, giving a 77 % yield of the desired product. The described reaction may find application in the conversion of lignin components into diverse hydroxyaromatic building blocks and generally offers potential for new, mild methods for efficient unmasking of phenols.

Enantio- and regioselective ene-reductions using F420H2-dependent enzymes.

In the past decade it has become clear that many microbes harbor enzymes that employ an unusual flavin cofactor, the F420 deazaflavin cofactor. Herein we show that F420-dependent reductases (FDRs) can successfully perform enantio-, regio- and chemoselective ene-reductions. For the first time, we have demonstrated that F420H2-driven reductases can be used as biocatalysts for the reduction of α,ß-unsaturated ketones and aldehydes with good conversions (>99%) and excellent regioselectivities and enantiomeric excesses (>99% ee). Noteworthily, FDRs typically display an opposite enantioselectivity when compared to the well established FMN-dependent Old Yellow Enzymes (OYEs).

Mining the Genome of Streptomyces leeuwenhoekii: Two New Type I Baeyer-Villiger Monooxygenases From Atacama Desert.

Actinobacteria are an important source of commercial (bio)compounds for the biotechnological and pharmaceutical industry. They have also been successfully exploited in the search of novel biocatalysts. We set out to explore a recently identified actinomycete, Streptomyces leeuwenhoekii C34, isolated from a hyper-arid region, the Atacama desert, for Baeyer-Villiger monooxygenases (BVMOs). Such oxidative enzymes are known for their broad applicability as biocatalysts by being able to perform various chemical reactions with high chemo-, regio-, and/or enantioselectivity. By choosing this specific Actinobacterium, which comes from an extreme environment, the respective enzymes are also expected to display attractive features by tolerating harsh conditions. In this work, we identified two genes in the genome of S. leeuwenhoekii (sle_13190 and sle_62070) that were predicted to encode for Type I BVMOs, the respective flavoproteins share 49% sequence identity. The two genes were cloned, overexpressed in E. coli with phosphite dehydrogenase (PTDH) as fusion partner and successfully purified. Both flavin-containing proteins showed NADPH-dependent Baeyer-Villiger oxidation activity for various ketones and sulfoxidation activity with some sulfides. Gratifyingly, both enzymes were found to be rather robust by displaying a relatively high apparent melting temperature (45°C) and tolerating water-miscible cosolvents. Specifically, Sle_62070 was found to be highly active with cyclic ketones and displayed a high regioselectivity by producing only one lactone from 2-phenylcyclohexanone, and high enantioselectivity by producing only normal (-)-1S,5R and abnormal (-)-1R,5S lactones (ee > 99%) from bicyclo[3.2.0]hept-2-en-6-one. These two newly discovered BVMOs add two new potent biocatalysts to the known collection of BVMOs.

The Biocatalytic Synthesis of Syringaresinol from 2,6-Dimethoxy-4-allylphenol in One-Pot Using a Tailored Oxidase/Peroxidase System.

Syringaresinol was synthesized in a one-pot conversion containing eugenol oxidase (EUGO) and horseradish peroxidase (HRP) using the relatively cheap 2,6-dimethoxy-4-allylphenol as a substrate. This conversion is fully coupled as the hydrogen peroxide generated from the reaction of EUGO with the substrate is utilized by the HRP to convert the formed sinapyl alcohol into syringaresinol. To improve the performance of EUGO on 2,6-dimethoxy-4-allylphenol, structure-inspired enzyme engineering was performed. This yielded the I427A EUGO mutant that is significantly more efficient with 2,6-dimethoxy-4-allylphenol. The I427A EUGO mutant together with HRP were capable of efficiently producing syringaresinol as a major product. After optimization and upscaling the conversion to a semipreparative scale (1 gr), syringaresinol was obtained in 81% yield.

Central mucoepidermoid carcinoma of the mandible ­ A case report.

Introduction: Mucoepidermoid carcinoma, compared to other tumors of salivary glands, occurs in 5­10% of cases. Histopathologically, it is divided into a well differentiated tumor that is of low-grade of malignancy, and a medium and poorly differentiated tumor of high grade of malignancy. Central mucoepidermoid carcinoma (CMEC) of the mandible was firstly described by Lepp in 1936, on a 66-year-old female patient. CMEC is characterized by atypical clinical image and radiological manifestation. Case Outline: A 55-year-old female patient was examined at the Clinic of Dentistry in Nis, Serbia, with anamnestic data regarding the presence of painless swelling in the right side of the mandible. Considering the histopathological results and presence of enlarged lymph nodes, right hemimandibulectomy and tumour excision from pterygomandibular space followed by supraomohyoid neck dissection was done. In due course, postoperative radiotherapy was applied (60 Gy) Conclusion: CMEC represents a rare tumor, characterized by local tissue destruction and ability to metastasize. Initial biopsy represented the key in preoperative planing. Radical excision with neck lymph node dissection followed by postoperative radiotherapy in our case represent a successful method of treating CMEC of the mandible.

An aldol approach to the enantioselective synthesis of (-)-oseltamivir phosphate.

A formal asymmetric synthesis of the antiviral agent (-)-oseltamivir phosphate is achieved using two aldol reactions as key steps.