Nanodiamond (ND) particles are popular platforms for the immobilization of molecular species. In the present research, enzyme Escherichia coli inorganic pyrophosphatase (PPase) was immobilized on detonation ND through covalent or noncovalent bonding and its enzymatic activity was characterized. Factors affecting adsorption of PPase such as ND size and surface chemistry were studied. The obtained material is a submicron size association of ND particles and protein molecules in approximately equal amounts. Both covalently and noncovalently immobilized PPase retains a significant enzymatic activity (up to 95% of its soluble form) as well as thermostability. The obtained hybrid material has a very high enzyme loading capacity (∼1 mg mg(-1)) and may be considered as a promising delivery system of biologically active proteinaceous substances, particularly in the treatment of diseases such as calcium pyrophosphate crystal deposition disease and related pathologies. They can also be used as recoverable heterogeneous catalysts in the traditional uses of PPase.
Tritium labeling was introduced into detonation nanodiamonds (ND) through the tritium thermal activation method. Two target preparation techniques were developed to increase the radioactivity and the specific radioactivity of the labeled product: the desiccation of the waterless solvent suspension and the lyophilization of the hydrosol. The specific radioactivity of the labeled product was shown to correlate with the hydrogen content in the starting material and to achieve 2.6 TBq/g.
Antiarrhythmic activities of KLN-93 (crystaUographically homogeneous paraaminobenzoic acid ester derivative), dicaine, and lidocaine in cats with neurogenic atrial fibrillation rank in the order in which these agents are named and depend on their vagolytic but not cardiotropic effect whose intensity decreases in the following series: dicaine>lidocaine> KLN-93. Key Words: neurogenic atrial fibrillation; local anesthetics; antiarrhythmic effect; vagolytic effect; cardiotropic effectLocal anesthetics lidocaine, trimecaine, richlocaine, etc., exert antiarrhythmic effect which is determined by molecular structure of these drugs [1,4]. This prompts thorough studies of antiarrhythmic activities of not only known local anesthetics, but also of new compounds with such effects, one of which is crystallographically homogeneous derivative of paraaminobenzoic acid ester (laboratory name prepared at the Bioeffect Institute.An important aspect of the problem is selection of the optimal model of cardiac arrhythmia; we consider neurogenic atrial fibrillation (NAF) easily induced in healthy animals as such a model [5,9,10]. It is maximally similar to natural cardiac rhythm disorders which usually develop in subjects with satisfactory somatic and hemodynamic status. We compared the antiarrhythmic effects of KLN-93, dicaine, and lidocaine in neurogenously induced atrial arthythmia. MATERIALS AND METHODSExperiments were carried out on 36 cats weighing 2.5-4.5 kg narcotized intraperitoneally with Chloralose and Nembutal in doses of 75 and 15 mg/kg, Department of Pharmacology, Department of Normal Physiology, Kuban State Medical Academy, Krasnod~r; Bioeffect Institute, Ministry of Science and Technological Strategy, Moscow respectively, under conditions of forced ventilation at body temperature 37~ In all animals the right vagus nerve was cut on the neck; the peripheral end of the nerve was stimulated by an ESU-2 electric stimulator (2 msec, 40 Hz, 6 thresholds) or with a single flash of pulses (2 msec, 40 Hz, 6 thresholds, 3 pulses) synchronously with the P wave [5,6]. Bipolar platinum probes were inserted through the right jugular and femoral veins. One probe served as a lead for intra-atrial ECG through cardiosynchronizing block of an original design [8], the other served for stimulation of the atrium (5 msec, 1.5'4.0 threshold) with an ESU-2 stimulator [7]. The ECG was recorded by an N3031-4 automated recorder, the processes were visually assessed using an IM-789 oscillograph.The duration of the P-P (To) and P-Q intervals, time of sinoatrial conduction of excitation [5,11,12], excitation thresholds for the vagus nerve and atrium, the effective refractory period of the atrium, and synchronizing (within the cycle) and tonic components of the chronotropic effect during stimulation of the vagus nerve with a single flash of pulses were assessed [5,6]. Manifestation of the intracycle component was assessed from the prolongation of the cardiocycle, during which test flash of pulses was delivered, and tonic effect was estimated from the m...
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