Ethynylation of Cysteine Residues: From Peptides to Proteins in Vitro and in Living Cells.

Current approaches to introduce terminal alkynes for bioorthogonal reactions into biomolecules still present limitations in terms of either reactivity, selectivity, or adduct stability. We present a method for the ethynylation of cysteine residues based on the use of ethynylbenziodoxolone (EBX) reagents. The acetylene group is directly introduced onto the thiol group of cysteine and can be used for copper-catalyzed alkyne-azide cycloaddition (CuAAC) without further processing. Labeling proceeded with reaction rates comparable to or higher than the most often used iodoacetamide on peptides or maleimide on the antibody trastuzumab, and high cysteine selectivity was observed. The reagents were also used in living cells for cysteine proteomic profiling and displayed improved coverage of the cysteinome compared to previously reported iodoacetamide or hypervalent iodine reagents. Fine-tuning of the EBX reagents allows optimization of their reactivity and physical properties.

Margaret Dix, Charles Hallpike and the 'Lagerungs' Manoeuvre.

The main objective of this manuscript is to describe some personal and professional aspects of two outstanding researchers and pioneers in neuro-otology. Among other achievements, Margaret Ruth Dix, and Charles Skinner Hallpike, designed the most-used provocative test for positional nystagmus for the diagnosis of lithiasis in the vestibular posterior semicircular canal.

Margaret Dix, Charles Hallpike and the 'Lagerungs' Manoeuvre / Margaret Dix, Charles Hallpike e a Manobra 'Lagerungs'

ABSTRACT The main objective of this manuscript is to describe some personal and professional aspects of two outstanding researchers and pioneers in neuro-otology. Among other achievements, Margaret Ruth Dix, and Charles Skinner Hallpike, designed the most-used provocative test for positional nystagmus for the diagnosis of lithiasis in the vestibular posterior semicircular canal.

RESUMO O principal objetivo desse manuscrito diz respeito a alguns aspectos pessoais e profissionais de dois excelentes pesquisadores e pioneiros da neuro-otologia. Entre outras descrições, Margaret Ruth Dix e Charles Skinner Hallpike descreveram o teste provocativo mais utilizado de nistagmo posicional para o diagnóstico de litíase no canal semicircular posterior do sistema vestibular.

Metal-Free Oxidative Cross Coupling of Indoles with Electron-Rich (Hetero)arenes.

A new method for the synthesis of bi-heteroaryls is reported, based on the umpolung of indoles with benziodoxol(on)e hypervalent iodine reagents (IndoleBX). The oxidative coupling of IndoleBX with an equimolar amount of electron-rich benzenes, indoles, pyrroles, and thiophenes proceeded under mild transition-metal-free conditions. Functionalized non-symmetrical bi-indolyl heterocycles were accessed efficiently. Introduction of a new type of C2-substituted indole benziodoxole reagents further allowed extending the scope of the reaction to NH unprotected and C3-alkylated indoles. The obtained bi-heterocycles are important building blocks in synthetic and medicinal chemistry, and could be easily transformed into more complex heterocyclic systems.

Dearomative Diallylation of N-Acylindoles Mediated by FeCl3.

Three-dimensional indolines possessing two contiguous-stereogenic centers were obtained stereoselectively via the FeCl3-mediated dearomative introduction of two allyl groups to N-acylindoles with allyltrimethylsilane. Synthetic transformations allowed obtention of trans-tetrahydrocarbazoles and an aza[4.4.3]propellane scaffold by RCM. Selective hydration of one of the allyl groups was also achieved.

Revealing the electrophilicity of N-Ac indoles with FeCl3: a mechanistic study.

Herein, we report a mechanistic exploration of the unusual FeCl3-mediated hydroarylation of N-Ac indoles. Electron density topology analysis of a crystal, in situ IR monitoring, Hammett and Taft studies as well as DFT computations allowed us to determine that activation of acetyl with FeCl3 and of the C2[double bond, length as m-dash]C3 bond with a proton is involved.

Binding interaction of phosphorus heterocycles with bovine serum albumin: A biochemical study.

Interaction between bovine serum albumin (BSA) and phosphorus heterocycles (PHs) was studied using multi-spectroscopic techniques. The results indicated the high binding affinity of PHs to BSA as it quenches the intrinsic fluorescence of BSA. The experimental data suggested the fluorescence quenching mechanism between PHs and BSA as a dynamic quenching. From the UV-vis studies, the apparent association constant (Kapp) was found to be 9.25×102, 1.27×104 and 9.01×102 L/mol for the interaction of BSA with PH-1, PH-2 and PH-3 respectively. According to the Förster's non-radiation energy transfer (FRET) theory, the binding distances between BSA and PHs were calculated. The binding distances (r) of PH-1, PH-2 and PH-3 were found to be 2.86, 3.03, and 5.12 nm, respectively, indicating energy transfer occurs between BSA and PHs. The binding constants of the PHs obtained from the fluorescence quenching data were found to be decreased with increase of temperature. The negative values of the thermodynamic parameters ΔH, ΔS and ΔG at different temperatures revealed that the binding process is spontaneous; hydrogen bonds and van der Waals interaction were the main force to stabilize the complex. The microenvironment of the protein-binding site was studied by synchronous fluorescence and circular dichroism (CD) techniques and data indicated that the conformation of BSA changed in the presence of PHs. Finally, we studied the BSA-PHs docking using Autodock and results suggest that PHs is located in the cleft between the domains of BSA.

Intermolecular dearomative C2-arylation of N-Ac indoles activated by FeCl3.

We report the FeCl3-mediated direct addition of electron-rich arenes to the C2-position of electrophilic N-Ac indoles under mild conditions (room temperature, air). No functional group is required on the arene nucleophile: one of its C-H bonds is added to the C2[double bond, length as m-dash]C3 double bond of the indole nucleus in a Friedel-Crafts-type reaction. This dearomatisation process delivered a broad range of C2-arylated indolines.

Synthesis of 3,3-Spiroindolines via FeCl3-Mediated Cyclization of Aryl- or Alkene-Containing 3-Substituted N-Ac Indoles.

We report the cyclization of 3-substituted N-acetylindoles for the straightforward synthesis of 3,3-spiroindolines via the Friedel-Crafts reaction of an appended aryl group or the formal [2 + 2] cycloaddition of an appended alkene. Our strategy involves an Umpolung of the C2═C3 bond of the indole nucleus during FeCl3-mediated hydroarylation or annulation reactions.

Development and assessment of the vestibular system.

Paediatric vestibular assessment is necessary in various situations, yielding invaluable information relating to diagnoses and allowing for the formulation of appropriate rehabilitative strategies when considering the management of children with vestibular and balance problems, alone or in association with hearing impairment or other developmental disorders. The development and assessment of the vestibular system is considered in this article.

Diphtheria: the patch remains.

This study analysed the number of patients admitted with diphtheria to a teaching hospital in the state of Assam in India over a period of five years and compared the disease characteristics and management with outcomes and incidences of diphtheria reported in the literature. It was a retrospective analysis of data elicited from clinical records of patients admitted to hospital. A total of 101 admissions were recorded during a five-year period between March 1997 to March 2002, mostly with pharyngeal diphtheria (90 per cent). The majority of patients had no history of immunization (70 per cent). Significant presenting features were a tonsillar patch, sore throat, respiratory distress and fever. All patients were treated with anti-diphtheritic serum and intravenous antibiotics. Steroids were given to 81 per cent of patients and tracheostomy was carried out in 10 per cent of cases. The mortality was 16 per cent. Diphtheria of the respiratory tract remains a potentially fatal disease commonly presenting with membranous pharyngitis. Early diagnosis and treatment with anti-diphtheritic serum and antibiotics remain the cornerstone of treatment. Inadequate immunization cover is deemed responsible for the continued menace of diphtheria.