Search results for "dimer"
showing 10 items of 558 documents
Preparation and reactions of palladium(II) complexes with C2-bonded heteroaromatic ligands trans[PdCl(RN)(PPh3)2] (RN = 2-pyridyl, 2-pirazyl, 2-pyrim…
1986
Abstract The complexes trans -[PdCl(R N )(PPh 3 ) 2 ] (I) [R N = 2-pyridyl (2-Py), 2-pyrazyl (2-pyz), 2-pyrimidyl (2-pym) group] have been prepared in high yield by deprotonation with NEt 3 of the corresponding cationic compounds trans [PdCl(R N H) (PPh 3 ) 2 ] + (R N H = N -protonated C 2 -heteroaromatic ligand) in the presence of an excess of PPh 3 . In chlorinated solvents, complexes I undergo a slow reversible dimerization into the binuclear derivatives [PdCl(μ-R N )(PPh 3 )] 2 (II) (μ-R N = C 2 , N 1 -bridging ligand). From the 31 P NMR spectra in 1,2-dichloroethane the following dissociation constants were obtained: 1.9 mol 1 −1 (R N = 2-py), 5.1 × 10 −2 (2-pym), 6.6 × 10 −3 (2-pyz). …
Exploring reactivity of a bis-sulfonium zirconocene-ate dimer: synthesis of various zwitterionic phosphonium anionic zirconocene complexes
2007
Abstract Formal [3+2] cycloaddition reactions between the bis-sulfonium zirconocene-ate dimer 1a and methylpropiolate, benzaldehyde and carbon disulfide afforded stable zwitterionic phosphonium zirconocene-ate complexes 2–4, respectively, with two orthocondensed five-membered heterocycles. X-ray crystal structure of 4 has been determined. Elemental chalcogens (S, Se, Te) gave rise also to a new variety of five-coordinate zirconium(IV) complexes (5–7) by a formal [3+1] cycloaddition reaction. In these bicyclic zirconates, sulfur is included in a five-membered ring while the second chalcogen is in a four-membered one.
D-dimer for risk stratification in haemodynamically stable patients with acute pulmonary embolism
2015
Patients with submassive pulmonary embolism (PE) have a higher short-term mortality than those with low-risk PE. Rapid identification of submassive PE is important for adequate treatment of non-massive PE. We aimed to investigate the utility of D-dimer for the prediction of submassive PE stadium in normotensive PE patients.Normotensive PE patients were classified into submassive or low-risk PE groups. In addition to the comparison of the groups, area under the curve (AUC) and D-dimer cut-off for the prediction of submassive PE stadium, multi-variate logistic regression for association between D-dimer values above this cut-off and submassive PE stadium were also calculated.The data of 129 no…
High-Yield Synthesis of 20-, 24-, and 28-Membered Macropentolide, -hexolide, and -heptolide, Respectively, from (R)- or (S)-3-hydroxybutanoic acid un…
1988
The macrocyclic pentolide 1, hexolide 2, and heptolide 3 constitute ca. 80% of the oligomers formed in ca. 50% yield from enantiomerically pure 3-hydroxybutanoic acid under Yamaguchi's macrolactonization conditions. The FAB mass spectra of the MH+, M Na+, and MCs+ are reported (Figs. 2, 3, 5, and 6). No cyclic tetramer is detected. The 1H-NMR spectra of the cyclic oligomers, of the monomer, and of the polymer (PHB) are very similar (Fig. 4). Directed synthesis of the open-chain dimer and tetramer of 3-hydroxybutanoic acid and attempted cyclization do not lead to the isolation of the cyclic tetramer.
D-dimer concentrations in acute urticaria in children
2021
Introduction: Urticaria is a clinical entity presenting as wheals, angioedema, or both simul-taneously. Elevated D-dimer levels were reported in the course of chronic spontaneous urticaria. Data regarding D-dimer levels in acute urticaria in children are limited. Objectives: To assess potential associations between duration of glucocorticosteroid (GCS) therapy and D-dimer concentrations in children with acute urticaria. Patients, materials, and methods: Hospital records of 106 children (59 females), aged 5.57 ± 4.91 years, hospitalized in 2014–2018 were analyzed retrospectively. The study group consisted of pediatric patients admitted to the hospital due to severe acute urticaria resistant …
SiRNA-mediated selective inhibition of mutant keratin mRNAs responsible for the skin disorder pachyonychia congenita.
2006
RNA interference offers a novel approach for treating genetic disorders including the rare monogenic skin disorder pachyonychia congenita (PC). PC is caused by mutations in keratin 6a (K6a), K6b, K16, and K17 genes, including small deletions and single nucleotide changes. Transfection experiments of a fusion gene consisting of K6a and a yellow fluorescent reporter (YFP) resulted in normal keratin filament formation in transfected cells as assayed by fluorescence microscopy. Similar constructs containing a single nucleotide change (N171K) or a three-nucleotide deletion (N171del) showed keratin aggregate formation. Mutant-specific small inhibitory RNAs (siRNAs) effectively targeted these site…
Bitterness and astringency of flavan-3-ol monomers, dimers and trimers
1999
Intensity of astringency and bitterness of seven flavonoid compounds was evaluated by a time-intensity (TI) procedure. Eighteen trained judges rated intensity continuously from ingestion, through expectoration at 10 s until extinction of the sensation. The seven stimuli included two flavan-3-ol monomers, (+)-catechin and (−)-epicatechin, three dimers and two trimers synthesised from catechin or epicatechin by condensation with (+)-dihydroquercitin. As the degree of polymerisation increased, maximum bitterness intensity (Imax) and total duration (Ttot) decreased whereas astringency Imax increased. The monomers were significantly higher in bitterness at Imax than the dimers, which were signif…
Unusual case of continuous urinary dribbling in a young female due to unknown complex urogenital malformation: magnetic resonance features
2020
Congenital anomalies of kidney and urinary tract (CAKUT) occur in up to 3.2% of infants, and in almost one third of cases they are associated to genital aberrations. DMSA renal scintigraphy is considered the gold standard in CAKUT patients, to assess renal function, depict and locate ectopic kidney and to guide eventual surgical management. Recent cases have shown the noticeable limit of scintigraphy in detecting poorly functional renal moieties and associated genital anomalies; thus leading to a substantial delay in therapy, and, in females, to severe uro-gynecological complications. We herein describe a case of a young girl with unusual urinary dribbling, where DSMA scintigraphy was not d…
D-dimer testing: advantages and limitations in emergency medicine for managing acute venous thromboembolism
2007
Patients with suspected deep vein thrombosis (DVT) or pulmonary embolism (PE) are frequently admitted to an Emergency Department (ED) for initial evaluation. However, management of patients with suspicion of acute venous thromboembolism (VTE) in this clinical setting can be difficult; in fact symptoms and signs of DVT are non-specific and can be found in a broad spectrum of non-thrombotic disorders. An accurate and timely objective diagnosis is necessary for immediate and correct identification of patients with acute VTE, while avoiding the bleeding risk associated with unnecessary anticoagulant therapy in patients where DVT or PE have been ruled out. The diagnostic approach to patients wit…
Postoperative Reduction of Fibrinolysis as a Prognostic Factor of Fatal Outcome
2001
For the resection of an esophagus carcinoma a mortality rate of 2 to 30% was described, It is still unclear whether an abdominothoracic or transhiatal intervention is superior regarding the outcome. To investigate the prognostic value of fibrinolytic markers, plasmin-α2-antiplasmin (PAP) and D-dimer (DD) values were determined daily in the early postoperative period for 11days. In addition, the course of PAP and DD concentrations was compared with the method of esophagectomy. Of the 28 patients enclosed in the study, 5 died between day 10 and day 34 owing to adult respiratory distress syndrome and septicemia. The PAP and DD concentrations increased in survivors after surgery until day 5 an…