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A N Plotnikov

Publications and source records attributed to A N Plotnikov.

29 records · Page 2Linked to original sources
PubMed1996

The calcium-independent receptor of alpha-latrotoxin is not a neurexin.

alpha-Latrotoxin (alpha-LTx), a vertebrate neurotoxin isolated from Black Widow Spider venom, causes massive spontaneous neurotransmitter release. The molecular mechanism(s) by which the toxin exerts its effect is largely unknown. Here we report identification and purification of a novel membrane receptor with high affinity for alpha-LTx. Unlike neurexin Ia, a previously described high affinity alpha-LTx receptor, this novel protein binds alpha-LTx independently of Ca2+ presence and therefore may be a mediator of the calcium-independent stimulation of neurotransmitter release by alpha-latrotoxin. The major protein component of calcium-independent alpha-LTx receptors is a novel M(r) 120,000 protein which does not belong to the neurexin family. Among several tissues tested, the M(r) 120,000 protein was found only in brain.

Amino Acid Sequence↗
PubMed1996

[Biosynthesis and conformational state of 17-kDa and 27-kDa N-terminal fragments of elongation factor EF-2 in solution].

N-Terminal fragments of the rat liver elongation factor EF-2 containing 162 (17 kDa) and 244 (27 kDa) amino acid residues of 857 (95 kDa) residues of the native protein were synthesized in E. coli cells and in a wheat germ cell-free translation system, and their conformations were studied. Both fragments were synthesized as inclusion bodies (nonspecific molecular aggregates). The conformations of the fragments in a solution were studied at neutral pH values by CD, fluorescence spectroscopy, scanning microcalorimetry, viscosimetry, gel-filtration, limited proteolysis, and interaction with monospecific anti-EF-2 antibodies and GroEL/ES molecular chaperone. Under nondenaturing conditions, both fragments existed in a solution as associates within a broad range of molecular masses, contained a considerable amount of elements of the intramolecular secondary structure, and represented globules without rigid tertiary structure (molten globules). A rigid tertiary structure was not formed even after the interaction of the fragments with the GroEL/ES molecular chaperone, thus indicating that the C-terminal fragment is essential for the formation of the rigid tertiary structure. Both fragments contained conformational antigenic determinants similar to those in the whole protein; i.e., despite the absence of the rigid tertiary structure, the fragments contained elements whose structure was similar to that of the corresponding regions in the whole protein.

Animals↗
PubMed1993

[The clinical aspects of using thrombolytic therapy in myocardial infarct at the prehospital stage].

The examination of 80 patients with acute myocardial infarction has revealed that prehospital thrombolytic therapy (TT) allows it to be initiated significantly earlier by 2.9 hours, resulting in coronary reperfusion and ensuring more complete blood flow recovery than hospital therapy. The natural history of the disease is also more favourable when TT is used in the prehospital period. It is concluded that with strict observance of indications and contraindications, TT used by an emergency team in the prehospital period is no more dangerous than in the hospital period.

Aged↗
PubMed1993

[A trial of the use of a new thrombolytic preparation--recombinant tissue-type plasminogen activator--in myocardial infarct patients].

Search for more effective and safe drugs has recently led to the design of second-generation thrombolytic enzymes one of which is recombinant tissue plasminogen activator. A total of 80 patients including 41 who received tissue plasminogen activator (TPA) (Group 1), 39 on streptokinase (SK) (Group 2) were examined. By the 90th minute of thrombolytic infusion, coronary blood flow was recovered in 27 (66%) patients from Group 1 and 19 (49%) from Group 2 (p = 0.12). A decrease in fibrinogen concentration by less than 1 g/l was seen in 7 (18.4%) patients from Group 1 and in 29 (82.9%) patients from Group 2 (p = 0.00005). The levels of fibrinogen and plasminogen during 36 hours of initiation of thrombolytic infusion were statistically significantly lower in Group 2. The incidence of hemorrhages was the same in the two groups and equal to 26.8 and 28.0% in Groups 1 and 2, respectively. All the patients had no hemorrhages requiring transfusion of blood and its substitutes, as well as no cerebral circulatory disorders in the first week of the disease.

Adult↗
PubMed1991

[Modern aspects of reduction of mortality in acute appendicitis in children under three years of age].

The experience with treatment of 216 young children with acute appendicitis is summarized. All the patients were operated on after the complex preoperative preparation. Median laparotomy was performed in 17 patients, 199 were operated on with local approach. Sanation of the abdominal cavity, intestinal decompression were performed. At the postoperative period, the correction of metabolic disorders, hemosorption, lymphosorption, endolymphatic antibiotic therapy, intravascular laser and ultra-violet irradiation of the blood were performed. One patient, who was admitted 10 days after the onset of the disease died. There are the following reserves for reduction of lethality: timely taking medical advice, early diagnosis of the disease, effective preoperative preparation, adequate operative intervention and postoperative management of a patient, timely detection and elimination of complications.

Acute Disease↗
PubMed1990

[Possibilities of the use of 99mTc pyrophospate myocardial scintigraphy in the early period of myocardial infarct in the evaluation of the effectiveness of thrombolytic therapy].

In early (mean time, 6.9 +/- 0.2 hours following the onset of an anginal episode), 99mTc pyrophosphate myocardial scintigraphy was performed in 28 patients who received thrombolytic therapy under angiographic monitoring. The sensitivity and specificity of an early administration of pyrophosphate into the myocardium as a noninvasive marker of successful coronary reperfusion was 95.7% and 100%, respectively.

Adult↗
PubMed1990

[Thrombolytic treatment of myocardial infarction at the prehospital and hospital stage].

Thrombolytic therapy was performed in 59 patients within the first hours of myocardial infarction. Twenty three patients (Group 1) were given streptokinase (SK) by an emergency team, 36 patients (Group 2) received SK following coronary angiography. In Group 1, SK was initiated earlier (p less than 0.001) than in Group 2. In Group 1 there was no coronary artery occlusion in the appropriate site of myocardial infarction in 86% of the patients. In Group 2, coronary occlusion was detected in 88% reperfusion, in 50% of the cases. Severe overall and regional left ventricular contractility abnormalities were found within the first month of the disease. The incidence of complications is the same in the two groups. High efficiency and relatively safe of thrombolytic therapy in the prehospital period makes this method particularly promising for practical medicine.

Adult↗
PubMedDate not supplied

[Structure-activity domain of elongation factor EF-2. Analysis of fragments of limited EF-2 hydrolysis, obtained using trypsin and elastase].

Limited hydrolysis of EF-2 with trypsin in mild conditions leads to cleavage at the N-terminal part of the protein, at the region of phosphorylation, at the Arg54 and Arg65 residues. The trypsinolysis product, fragment T1', containing Thr56 and Thr58, which are phosphorylated in EF-2, is also phosphorylated by EF-2-kinase at the same residues. In the phosphorylated EF-2, digestion by trypsin takes place only at Arg65, resulting in a reduction of the rate of hydrolysis in comparison with the native EF-2. Digestion of EF-2 with elastase results in the formation of two fragments E1 and E2 (60 and 40 kDa, respectively). Fragment E1 represents the N-terminal part of EF-2. It is resistant to the further action of elastase, is not cleaved by trypsin, and loses its capability for phosphorylation. Fragment E2, the C-end part of the molecule, is not resistant to the further action of elastase and retains its capability for ADP-ribosylation with the A fragment of diptheria toxin and NAD+. Electrophoretic analysis of EF-2 and its proteolytic fragments according to O'Farrell showed that the modification, resulting in the presence of two initial forms of EF-2, is located between the amino acid residues 66 and 506 of the polypeptide chain. In conclusion a possibility of studying the formation of partial functional activities within the framework of individual structure-functional domains using a set of N-terminal fragments of various length is discussed.

Adenosine Diphosphate Ribose↗