Publications by authors named "Dan Dumitrescu"

16 Publications

  • Page 1 of 1

Acute surgical abdomen during the COVID-19 pandemic: Clinical and therapeutic challenges.

Exp Ther Med 2021 May 22;21(5):519. Epub 2021 Mar 22.

Third Department of Surgery, Faculty of Medicine, 'Lucian Blaga' University Sibiu, 550169 Sibiu, Romania.

The present study investigated the effects of the COVID-19 pandemic on the clinical presentation and therapeutic management of acute surgical abdomen. A retrospective study of emergency hospitalizations with a diagnosis of acute surgical abdomen between April and July 2020 vs. a similar period in 2019 was performed. The observation sheets and the operating protocols were analyzed. Between April and July 2020, 50 cases of acute surgical abdomen were hospitalized and treated, compared to 43 cases in the same period last year. The main types of pathology in both groups included: Occlusions (60%, respectively 44.2% in 2019) and peritonitis (32%, respectively 41.8% in 2019). There was an increased rate of patients with colorectal cancers neglected therapeutically or uninvestigated, who presented during the pandemic period with emergencies for complications such as occlusion or tumor perforation (32 vs. 6.97%, P=0.0039). One case, with gastric perforation, was COVID-positive, with no pulmonary symptoms at admission. The number of postoperative infectious complications was lower during the pandemic (2 vs. 13.95%, P=0.0461). As the COVID-19 pandemic appears to be still far from ending, we should learn to adapt our surgical protocols to the new evidence. Oncological patients are a vulnerable group, who were neglected in the first months of the pandemic. SARS-Cov-2 infection may be a cause of abdominal pain and should be taken into account in different diagnoses of acute abdomen in surgical wards. Correct wearing of adequate personal protective equipment (PPE) and respecting strict rules of asepsis and antisepsis are required for preventing in-hospital transmission of infection.
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http://dx.doi.org/10.3892/etm.2021.9950DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8014977PMC
May 2021

Europe's War against COVID-19: A Map of Countries' Disease Vulnerability Using Mortality Indicators.

Int J Environ Res Public Health 2020 09 9;17(18). Epub 2020 Sep 9.

Department of Management, Marketing and Business Administration, Lucian Blaga University of Sibiu, 550024 Sibiu, Romania.

Specific and older age-associated comorbidities increase mortality risk in severe forms of coronavirus disease (COVID-19). We matched COVID-19 comorbidities with causes of death in 28 EU countries for the total population and for the population above 65 years and applied a machine-learning-based tree clustering algorithm on shares of death for COVID-19 comorbidities and for influenza and on their growth rates between 2011 and 2016. We distributed EU countries in clusters and drew a map of the EU populations' vulnerabilities to COVID-19 comorbidities and to influenza. Noncommunicable diseases had impressive shares of death in the EU but with substantial differences between eastern and western countries. The tree clustering algorithm accurately indicated the presence of western and eastern country clusters, with significantly different patterns of disease shares of death and growth rates. Western populations displayed higher vulnerability to malignancy, blood-related diseases, and diabetes mellitus and lower respiratory diseases, while eastern countries' populations suffered more from ischaemic heart, cerebrovascular, and circulatory diseases. Dissimilarities between EU countries were also present when influenza was considered. The heat maps of EU populations' vulnerability to diseases based on mortality indicators constitute the basis for more targeted health policy strategies in a collaborative effort at the EU level.
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http://dx.doi.org/10.3390/ijerph17186565DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7558340PMC
September 2020

A positive to negative uniaxial thermal expansion crossover in an organic benzothienobenzothiophene structure.

Acta Crystallogr B Struct Sci Cryst Eng Mater 2020 Aug 21;76(Pt 4):661-673. Epub 2020 Jul 21.

Institut Européen des Membranes, IEM - UMR 5635, ENSCM, CNRS, Université de Montpellier, Montpellier, France.

Compound 6,6'-([1]benzothieno[3,2-b][1]benzothiophene-2,7-diyl)bis(butan-1-ol) (BTBT-C4OH) displays a continuous type 0 first-order isosymmetric phase transition at 200 K which is accompanied by a continuous change of the thermal expansion along the b axis from positive to negative. The equivalent isotropic atomic displacement parameters for all non-hydrogen atoms as well as all the eigenvalues of the anisotropic atomic displacement tensor show discontinuous behavior at the phase transition. The eigenvalues of the translational tensor in a rigid-body description of the molecule are all discontinuous at the phase transition, but the librational eigenvalues are discontinuous only in their temperature derivative. BTBT-C4OH displays a similar type of quasi-supercritical phase transition as bis(hydroxyhexyl)[1]benzothieno[3,2-b][1]benzothiophene (BTBT-C6OH), despite the difference in molecular packing and the very large difference in thermal expansion magnitudes.
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http://dx.doi.org/10.1107/S2052520620007702DOI Listing
August 2020

Insight into the Anticancer Activity of Copper(II) 5-Methylenetrimethylammonium-Thiosemicarbazonates and Their Interaction with Organic Cation Transporters.

Biomolecules 2020 08 20;10(9). Epub 2020 Aug 20.

Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Währinger Strasse 42, A-1090 Vienna, Austria.

A series of four water-soluble salicylaldehyde thiosemicarbazones with a positively charged trimethylammonium moiety ([HL]Cl, R = H, Me, Et, Ph) and four copper(II) complexes [Cu(HL)Cl]Cl (-) were synthesised with the aim to study (i) their antiproliferative activity in cancer cells and, (ii) for the first time for thiosemicarbazones, the interaction with membrane transport proteins, specifically organic cation transporters OCT1-3. The compounds were comprehensively characterised by analytical, spectroscopic and X-ray diffraction methods. The highest cytotoxic effect was observed in the neuroblastoma cell line SH-5YSY after 24 h exposure and follows the rank order: > > > > >[HL]Cl. The copper(II) complexes showed marked interaction with OCT1-3, comparable to that of well-known OCT inhibitors (decynium 22, prazosin and corticosterone) in the cell-based radiotracer uptake assays. The work paves the way for the development of more potent and selective anticancer drugs and/or OCT inhibitors.
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http://dx.doi.org/10.3390/biom10091213DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7565988PMC
August 2020

Progressive Folding and Adaptive Multivalent Recognition of Alkyl Amines and Amino Acids in p-Sulfonatocalix[4]arene Hosts: Solid-State and Solution Studies.

Chempluschem 2020 08 21;85(8):1615. Epub 2020 Jul 21.

Lehn Institute of Functional Materials, School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, P. R. China.

Invited for this month's cover is the group of Dr. Mihail Barboiu from the Institut Europeen des Membranes of Montpellier, France and the Lehn Institute of Functional Materials at Sun-yat Sen University in Guangzhou, China. The cover picture shows the molecular recognition of folded 1,ω-amino-acids guests within p-sulfonatocalix[4]arene host anions stabilized with alternating hydrated cations and water molecules. Read the full text of the article at 10.1002/cplu.202000232.
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http://dx.doi.org/10.1002/cplu.202000433DOI Listing
August 2020

Progressive Folding and Adaptive Multivalent Recognition of Alkyl Amines and Amino Acids in p-Sulfonatocalix[4]arene Hosts: Solid-State and Solution Studies.

Chempluschem 2020 08 14;85(8):1623-1631. Epub 2020 Apr 14.

Lehn Institute of Functional Materials, School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, P. R. China.

Calix[4]arenes have the ability to encapsulate biomimetic guests, offering interesting opportunities to explore their molecular recognition, very close to biological scenarios. In this study, p-sulfonatocalix[4]arene (C4 A) anions and hydrated alkali cations have been used for the in situ recognition of cationic 1,ω-diammonium-alkanes and 1,ω-amino-acids of variable lengths. NMR spectroscopy illustrates that these systems are stable in aqueous solution and the interaction process involves several binding states or stabilized conformations within the C4 A anion, depending of the nature of the guest. DOSY experiments showed that monomeric 1 : 1 host-guest species are present, while the cation does not influence their self-assembly in solution. The folded conformations observed in the solid-state X-ray single-crystal structures shed light on the constitutional adaptivity of flexible chains to environmental factors. Futhermore, a comprehensive screening of 30 single crystal structures helped to understand the in situ conformational fixation and accurate determination of the folded structures of the confined guest molecules, with a compression up to 40 % compared with their linear conformations.
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http://dx.doi.org/10.1002/cplu.202000232DOI Listing
August 2020

Nickel(II) Complexes with Redox Noninnocent Octaazamacrocycles as Catalysts in Oxidation Reactions.

Inorg Chem 2019 Aug 2;58(16):11133-11145. Epub 2019 Aug 2.

Institute of Inorganic Chemistry , University of Vienna , Währinger Strasse 42 , A-1090 Vienna , Austria.

Nickel(II) complexes with 15-membered (-) and 14-membered () octaazamacrocyclic ligands derived from 1,2- and 1,3-diketones and -methylisothiocarbohydrazide were prepared by template synthesis. The compounds were characterized by elemental analysis, electrospray ionization mass spectrometry, IR, UV-vis, H NMR spectroscopies, and X-ray diffraction. The complexes contain a low-spin nickel(II) ion in a square-planar coordination environment. The electrochemical behavior of - was investigated in detail, and the electronic structure of 1e-oxidized and 1e-reduced species was studied by electron paramagnetic resonance, UV-vis-near-IR spectroelectrochemistry, and density functional theory calculations indicating redox noninnocent behavior of the ligands. Compounds - were tested in the microwave-assisted solvent-free oxidation of cyclohexane by -butyl hydroperoxide to produce the industrially significant mixture of cyclohexanol and cyclohexanone (i.e., A/K oil). The results showed that the catalytic activity was affected by several factors, namely, reaction time and temperature or amount and type of catalyst. The best values for A/K oil yield (23%, turnover number of 1.1 × 10) were obtained with compound after 2 h of microwave irradiation at 100 °C.
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http://dx.doi.org/10.1021/acs.inorgchem.9b01700DOI Listing
August 2019

Self-Assembled Columnar Triazole Quartets: An Example of Synergistic Hydrogen-Bonding/Anion-π Interactions.

Angew Chem Int Ed Engl 2019 08 11;58(35):12037-12042. Epub 2019 Jul 11.

Lehn Institute of Functional Materials, School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, China.

The self-assembly of triazole amphiphiles was examined in solution, the solid state, and in bilayer membranes. Single-crystal X-ray diffraction experiments show that stacked protonated triazole quartets (T ) are stabilized by multiple strong interactions with two anions. Hydrogen bonding/ion pairing of the anions are combined with anion-π recognition to produce columnar architectures. In bilayer membranes, low transport activity is observed when the T channels are operated as H /X translocators, but higher transport activity is observed for X in the presence of the K -carrier valinomycin. These self-assembled superstructures, presenting intriguing structural behaviors such as directionality, and strong anion encapsulation by hydrogen bonding supported by vicinal anion-π interactions can serve as artificial supramolecular channels for transporting anions across lipid bilayer membranes.
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http://dx.doi.org/10.1002/anie.201904808DOI Listing
August 2019

Prospect of Thiazole-based γ-Peptide Foldamers in Enamine Catalysis: Exploration of the Nitro-Michael Addition.

Chemistry 2019 May 7;25(30):7396-7401. Epub 2019 May 7.

Institut des Biomolécules Max Mousseron, UMR CNRS-UM-ENSCM 5247, UFR des Sciences Pharmaceutiques et Biologiques, 15 Avenue Charles Flahault, 34093, Montpellier Cedex 5, France.

As three-dimensional folding is prerequisite to biopolymer activity, complex functions may also be achieved through foldamer science. Because of the diversity of sizes, shapes and folding available with synthetic monomers, foldamer frameworks enable a numerous opportunities for designing new generations of catalysts. We herein demonstrate that heterocyclic γ-peptide scaffolds represent a versatile platform for enamine catalysis. One central feature was to determine how the catalytic activity and the transfer of chiral information might be under the control of the conformational behaviours of the oligomer.
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http://dx.doi.org/10.1002/chem.201901221DOI Listing
May 2019

Adaptive Encapsulation of ω-Amino Acids and Their Guanidinium-Amide Congeners.

Org Lett 2016 11 19;18(21):5556-5559. Epub 2016 Oct 19.

Lehn Institute of Functional Materials, School of Chemistry and Chemical Engineering, Sun Yat-Sen University , Guangzhou 510275, China.

The binding and the encapsulation of the 6-aminohexanoic acid (1) and 11-aminoundecanoic acid (2) are achieved in aqueous solution and in crystalline Pyrene-box cages. Unexpectedly, the amino-guanidinium AG and the amino acids 1 or 2 are reacting in aqueous solution in the absence and in the presence of Pyrene-box cages. The formation of an amide bond between a carboxylic acid and the amino-guanidine unit under mild acidic conditions in water without the use a coupling reagent is extremely interesting and unexpected. The resulted adducts AG1 and AG2 show adaptive binding behaviors and compressions.
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http://dx.doi.org/10.1021/acs.orglett.6b02802DOI Listing
November 2016

New "pyrene box" cages for adaptive guest conformations.

Org Lett 2015 May 20;17(9):2178-81. Epub 2015 Apr 20.

Adaptive Supramolecular Nanosystems Group, Institut Européen des Membranes, ENSCM/UMII/UMR-CNRS 5635, Pl. Eugène Bataillon, CC 047, 34095 Montpellier Cedex 5, France.

The possibility of controlling the compression extent and the coiling shape of the 1,12-diammoniumdodecane guest is shown by changing the dimensions of the internal space of the host guanidinium 1,3,5,8 pyrene-tetrasulfonate PTS(4-) crystalline capsules by using guanidinium (G(+)), amino-guanidinium (AG(+)), and diaminoguanidinium (A2G(+)) cations.
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http://dx.doi.org/10.1021/acs.orglett.5b00779DOI Listing
May 2015

Adaptive binding and selection of compressed 1,ω-diammonium-alkanes molecular encapsulation in water.

Chem Sci 2015 Mar 12;6(3):2079-2086. Epub 2015 Jan 12.

Adaptive Supramolecular Nanosystems Group , Institut Européen des Membranes , ENSCM/UMII/UMR-CNRS 5635 , Pl. Eugène Bataillon , CC 047 , 34095 Montpellier, Cedex 5 , France . Email:

Guest molecules confined inside hollow molecular assemblies and thus protected from their environment can show unexpected structural behavior or special reactivity compared to their behavior in a bulk, unprotected environment. A special case is the coiling behavior of variable-length alkane chains in rigid hydrogen-bonded molecular cages. It has been found before that coiling may occur in such circumstances, but no experimental evidence concerning the exact conformation of the chains has yet been presented. We reveal in this study the self-assembly of a molecular cage in water and the crystalline state from three distinct components in which linear 1,ω-diammonium-alkanes chains are confined with different degrees of compression. The exact coiling behavior is determined from atomic resolution X-ray diffraction showing crenel-like conformations in the compressed state. Chemical selection can be obtained from mixtures of alkane chains the encapsulation of kinetically stable conformations observed during the encapsulation of pure components. Moreover, it was found that uncompressed and compressed chains can be competitively trapped inside the capsule. These findings may provide insight in areas to a better understanding of biological processes, such as the fatty acid metabolism.
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http://dx.doi.org/10.1039/c4sc03945aDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5654369PMC
March 2015

Progressive compression of 1,ω-diammonium-alkanes inside a rigid crystalline molecular cage.

Chem Commun (Camb) 2014 Nov;50(91):14086-8

Adaptative Supramolecular Nanosystems Group, Institut Européen des Membranes, ENSCM/UMII/UMR-CNRS 5635, Pl. Eugène Bataillon, CC 047, 34095 Montpellier Cedex 5, France.

We present herein the compression mechanisms of linear 1,ω-diammonium-alkanes, confined within a molecular cage self-assembled in water. The exact coiling behaviour is determined from atomic resolution X-ray diffraction and shows crenel-like conformations in the compressed states.
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http://dx.doi.org/10.1039/c4cc03866eDOI Listing
November 2014

Self-sorting of dynamic metallosupramolecular libraries (DMLs) via metal-driven selection.

Chem Commun (Camb) 2014 Mar;50(20):2621-3

Institut Européen des Membranes - ENSCM-UMII-CNRS 5635, Place Eugène Bataillon, CC 047, F-34095 Montpellier Cedex 5, France.

"Metal-driven" selection between finite mononuclear and polymeric metallosupramolecular species can be quantitatively achieved in solution and in a crystalline state via coupled coordination/stacking interactional algorithms within dynamic metallosupramolecular libraries - DMLs.
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http://dx.doi.org/10.1039/c3cc49673bDOI Listing
March 2014

Reply to A computational evaluation of the evidence for the synthesis of 1,3-dimethylcyclobutadiene in solid state and aqueous solution--beyond the experimental reality.

Chemistry 2013 Apr 15;19(15):4938-41. Epub 2013 Mar 15.

Following earlier reports on the photochemical synthesis of 1,3-dimethylcyclobutadiene in a protective host matrix, theoretical calculations for the formation of that adduct have been recently performed by Rzepa. The author formulated criticisms based mainly on density functional theory calculations of (1)H NMR spectra. According to Rzepa the calculated spectra do not correspond with our measured spectra, which leads him to the conclusion that our interpretation is wrong, and that mainly cyclobutadiene has not been stabilized or even synthesized; we believe, however, that the initial model that Rzepa used for his calculations does not correspond to chemical reality or is at the very least a crude simplification of it, which implies that his calculations cannot match, in every point, our experimental spectra. Rzepa's simplified models might be 'reasonable' from the theoretical point of view; however, in the case of assessment in the solid state, the theoretical setup does not force the system to preserve the confined stabilizing space defined by the crystalline matrix for encapsulated hosts in the solid state. Inversely, in the case of solution modeling, the theoretical setup is too rigid to properly assess the complex equilibria occurring in solution and to accurately determine the NMR spectra of exchanging species in solution. The inconsistency between our experimental results and the results of the theoretical models proposed by Rzepa is such that his conclusions are considered to be too far from experimental reality. Accurate modeling taking in account "reasonable" experimental details would be a worthwhile endeavor.
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http://dx.doi.org/10.1002/chem.201203235DOI Listing
April 2013

A constrained disorder refinement: "Reinvestigation of "Single-crystal X-ray structure of 1,3-dimethylcyclobutadiene" by M. Shatruk and I. V. Alabugin".

Chemistry 2013 Apr 15;19(15):4946-50. Epub 2013 Mar 15.

Shatruk and Alabugin propose an alternative structural model for the observed electron density that we have attributed to the photochemical formation of 1,3-dimethylcyclobutadiene in a protective solid crystalline matrix. The main criticism from Shatruk and Alabugin concerns the modeling of the disorder in the calixarene cavity and in particular the neglect of a residual electron density close to the O1 atom. We published (Chem. Eur. J. 2011, 17, 10021) our opinion concerning this "ignored peak" in the Supporting Information of the paper. The current response to the Correspondence demonstrates that Shatruk and Alabugin have over-modeled our data by assigning a small electron density peak, which is hardly more than the density corresponding to a hydrogen atom, to an under-occupied oxygen site, using inappropriate refinement contraints.
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http://dx.doi.org/10.1002/chem.201203234DOI Listing
April 2013