Validation of a measurement device for instrumented quantification of anterior translation and rotational assessment of the knee.

Purpose: A test setup for clinical use in the awake and non-anesthetized patient measuring anteroposterior translation and rotation of the knee joint is the subject of validation.

Methods: A measuring device featuring fixation of the foot at 30° of knee flexion with varus/valgus stress posts for the knee was developed. Tibial rotation (external/internal) was imposed with a torque of 2 Nm on the footrest with the ankle locked in dorsiflexion.

Nucleophilicities and Lewis basicities of isothiourea derivatives.

Rate and equilibrium constants for the reactions of a series of isothioureas with benzhydrylium ions have been measured photometrically. The data were employed to determine the nucleophilicities and nucleofugalities of isothioureas and compare them with those of other organocatalysts.

Quantification of the electrophilic reactivities of aldehydes, imines, and enones.

The rates of the epoxidation reactions of aldehydes, of the aziridination reactions of aldimines, and of the cyclopropanation reactions of α,β-unsaturated ketones with aryl-stabilized dimethylsulfonium ylides have been determined photometrically in dimethyl sulfoxide (DMSO). All of these sulfur ylide-mediated cyclization reactions as well as the addition reactions of stabilized carbanions to N-tosyl-activated aldimines have been shown to follow a second-order rate law, where the rate constants reflect the (initial) CC bond formation between nucleophile and electrophile. The derived second-order rate constants (log k(2)) have been combined with the known nucleophilicity parameters (N, s(N)) of the aryl-stabilized sulfur ylides 4a,b and of the acceptor-substituted carbanions 4c-h to calculate the electrophilicity parameters E of aromatic and aliphatic aldehydes (1a-i), N-acceptor-substituted aromatic aldimines (2a-e), and α,β-unsaturated ketones (3a-f) according to the linear free-energy relationship log k(2) = s(N)(N + E) as defined in J.

[TKA revision of semiconstraint components using the 3-step technique].

Objective: The surgical goal is to achieve a pain free and stable knee joint after revision total knee arthroplasty in three steps. An important component of the technique is the reproducible restoration of the joint line.

Indications: Revision total knee arthroplasty.

Synthesis and reactivity of highly nucleophilic pyridines.

3,4,5-Triamino-substituted pyridines are avid for electrophiles but are still willing to give them back. In these compounds three amino groups conjoin their forces into the heterocyclic nitrogen, making it a powerful Lewis base. A short and efficient synthesis is described, and the origin of its unique activity in nucleophilic organocatalysis is rationalized by kinetics and thermodynamic quantifications.

Counterion effects in iminium-activated electrophilic aromatic substitutions of pyrroles.

Electrophilic substitution of pyrroles by α,β-unsaturated iminium ions is slow in acetonitrile when only weakly basic counterions are present. When the reactions are carried out in the presence of KCF(3)CO(2), fast deprotonation of the intermediate σ-adducts occurs, and the rate constant for the rate-determining CC bond-forming step can be predicted from the electrophilicity parameter E of the iminium ion and the N and s parameters of the pyrroles.

Scope and limitations of cyclopropanations with sulfur ylides.

The rates of the reactions of the stabilized and semistabilized sulfur ylides 1a-g with benzhydrylium ions (2a-e) and Michael acceptors (2f-v) have been determined by UV-vis spectroscopy in DMSO at 20 °C. The second-order rate constants (log k(2)) of these reactions correlate linearly with the electrophilicity parameters E of the electrophiles 2 as required by the correlation log k(2) = s(N + E), which allowed us to calculate the nucleophile-specific parameters N and s for the sulfur ylides 1a-g. The rate constants for the cyclopropanation reactions of sulfur ylides with Michael acceptors lie on the same correlation line as the rate constants for the reactions of sulfur ylides with carbocations.

A practical guide for estimating rates of heterolysis reactions.

Chemists are well trained to recognize what controls relative reactivities within a series of compounds. Thus, it is well-known how the rate of ionization of R-X is affected by the stabilization of the carbocation R(+), the nature of the leaving group X(-), or the solvent ionizing power. On the other hand, when asked to estimate the half-life of the ionization of a certain substrate in a certain solvent, most chemists resign.

Effect of the "supersilyl" group on the reactivities of allylsilanes and silyl enol ethers.

Kinetics of the reactions of allylsilanes (1) and silyl enol ethers (2) with benzhydrylium ions (3) were studied by UV-vis spectroscopy in dichloromethane at 20 °C. The less than three times higher reaction rates of the tris(trimethylsilyl)silyl compounds in comparison to the corresponding trimethylsilyl compounds indicate that the previously reported strong electron-donating effect of the supersilyl group operates only in the α-position and not in the β-position.

Prehospital treatment of patients with acute myocardial infarction with bivalirudin.

Objectives: Patients with acute myocardial infarction are at high risk of dying within the first hours after onset of coronary ischemia. Therefore, pharmacological intervention should be started in the prehospital setting. This study investigates the effect of the prehospital administration of bivalirudin on short-term morbidity and mortality compared to heparin plus abciximab in patients with ST-segment-elevation myocardial infarction (STEMI).

Ambident reactivities of pyridone anions.

The kinetics of the reactions of the ambident 2- and 4-pyridone anions with benzhydrylium ions (diarylcarbenium ions) and structurally related Michael acceptors have been studied in DMSO, CH(3)CN, and water. No significant changes of the rate constants were found when the counterion was varied (Li(+), K(+), NBu(4)(+)) or the solvent was changed from DMSO to CH(3)CN, whereas a large decrease of nucleophilicity was observed in aqueous solution. The second-order rate constants (log k(2)) correlated linearly with the electrophilicity parameters E of the electrophiles according to the correlation log k(2) = s(N + E) (Angew.

Electrophilic reactivities of azodicarboxylates.

The kinetics of the reactions of the azodicarboxylates 1 with the enamines 2 have been studied in CH(3)CN at 20 °C. The reactions follow a second-order rate law and can be described by the linear free energy relationship log k(2) (20 °C) = s(N+E) (E = electrophilicity parameter, N = nucleophilicity parameter, and s = nucleophile-specific slope parameter). With E parameters from -12.

Electrophilic reactivities of 1,2-diaza-1,3-dienes.

The kinetics of the reactions of 1,2-diaza-1,3-dienes 1 with acceptor-substituted carbanions 2 have been studied at 20 °C. The reactions follow a second-order rate law, and can be described by the linear free energy relationship log k(20 °C)=s(N+E) [Eq. (1)].

[Recommendations of the AGA (German-speaking Arthroscopy Association) on equipment of facilities, process quality and qualification of surgeons for arthroscopic interventions].

Following closely the guidelines of the German Federal Medical Association for quality assurance of outpatient surgery, the AGA (German-speaking Arthroscopy Association) has formulated recommendations on quality standards in arthroscopic surgery. The surgical facility should implement a quality management system. Minimum standards of construction, apparatus, technical and hygiene facilities are included according to the directive of the German Federal Medical Association for quality assurance in outpatient surgery.

Therapeutic hypothermia after cardiac arrest in Lower Austria--a cross-sectional survey.

This study was undertaken to evaluate the use of therapeutic hypothermia (TH) after cardiac arrest in Lower Austria. A questionnaire was sent to intensive care units (ICUs) in Lower Austria. Methods of inducing and maintaining hypothermia, the practise of rewarming, concomitant therapies and reasons not to cool were documented.

Stabilities of trityl-protected substrates: the wide mechanistic spectrum of trityl ester hydrolyses.

Ionization rates of para-substituted triphenylmethyl (trityl) acetates, benzoates, and para-nitrobenzoates have been determined in aqueous acetonitrile and aqueous acetone at 25 degrees C. Conventional and stopped-flow techniques have been used to evaluate rate constants ranging from 1.38 x 10(-5) to 2.

Electrophilicity versus electrofugality of tritylium ions in aqueous acetonitrile.

First-order rate constants k(w) for the reactions of a series of donor-substituted triphenylmethylium (tritylium) ions with water in aqueous acetonitrile have been determined photometrically at 20 degrees C using stopped-flow and laser-flash techniques. The rate constants follow the linear free energy relationship log k(20 degrees C)=s(N+E). The reactivities k(w) of the methyl- and methoxy-substituted tritylium ions towards water correlate linearly with the corresponding pK(R(+) ) values with a Leffler-Hammond coefficient alpha=deltaDeltaG(++)/deltaDeltaG(0) of 0.

Nucleophilicities and Lewis basicities of imidazoles, benzimidazoles, and benzotriazoles.

The kinetics of the reactions of some imidazoles, benzimidazoles and benzotriazoles with benzhydrylium ions (diarylcarbenium ions) have been studied photometrically in DMSO, acetonitrile, and aqueous solution at 20 degrees C. The resulting second-order rate constants have been used to determine the nucleophile-specific parameters N and s of these azoles according to the linear-free-energy relationship log k (20 degrees C) = s(N + E). With N = 11.

Electrophilicities of alpha-chlorinating agents used in organocatalysis.

Kinetics of the reactions of the chlorinating agents 1a-c with pi-nucleophiles have been studied to include these compounds in our comprehensive electrophilicity scale.