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Biomedical subjects

N I Ivashchenko

Publications and source records attributed to N I Ivashchenko.

9 recordsLinked to original sources
PubMed1991

[Ectopic interactions of Drosophila melanogaster polytene chromosomes in the H-E system of hybrid dysgenesis].

Analysis of salivary gland polytene chromosomes of Drosophila melanogaster age III larvae has demonstrated that inversions make up high percentage of aberrations induced by transposition of the hobo element. The frequency of inversions increases upon irradiation. In view of the fact that transpositions of mobile elements and irradiation can considerably affect the homology of associating regions, ectopic chromosome contacts were analysed. On the one hand, this analysis has revealed general features for all types of crosses, such as the prevalence of intrachromosomal contacts over interchromosomal ones, predominant localization of both types of contacts in telomeric regions of chromosomes and lower frequency of their occurrence on X chromosome in males as compared with females. On the other hand, the specificity of ectopic conjugation in different types of crosses has been determined. Given a constant average frequency of ectopic contacts in the D. melanogaster genome, differences in their distribution in chromosomes have been detected. Chromosomes of pure lines differ from their homologues in dysgenic hybrids by distribution of ectopic conjugation peaks and by localization of a number of unique events. On the basis of our own experiments and literature data, the role of ectopic contacts as structural formations connecting chromosome regions similar in their functional activity, rather than in nucleic-protein characteristics, is discussed.

Animals↗
PubMed1990

[Mutational variability of enzyme loci in unstable Drosophila melanogaster strains].

Biochemical analysis of a number of related unstable Drosophila melanogaster strains was carried out. These strains have been shown to undergo mutational transformations caused by insertion/excision of transposable elements (Gerasimova, 1985). Activity and mobility variants of alpha-GPDH, ADH, SOD, G6PD, 6PGD and EST-6 were analysed. Two loci controlling SOD and 6PGD proved to be invariable, the loci alpha-Gpdh and Est-6 causing reduced activity of their products in the initial strain ctMR2. The direct and reversed transformations analogous to the mutational passages of morphological characters were traced in two loci controlling ADH and G6PD. The data obtained are discussed in terms of up-to-date views on the functional role of transposable elements, in relation to the genetic stability of the strains studied, under the multiple transpositions of mobile elements.

Animals↗
PubMed1990

[Effects of gamma-irradiation on the gonadal cells of Drosophila melanogaster under varying conditions of hybrid dysgenesis].

Comparative analysis was carried out with respect to the results of combined effects of gamma-irradiation and transposition of mobile elements in Drosophila, depending on the succession of their application. As turned out, introduction of the P and hobo elements into the M' line, prior to irradiation, resulted in decreased number of unfertilized eggs and reduced the proportion of flies killed at the larval and pupal stages. However, opposite effects were shown, when the P element was introduced following irradiation: the number of unfertilized eggs and that of the flies killed at the larval and pupal stages has significantly increased, as compared to the control. Interaction between the processes induced at the level of DNA repair both by gamma-irradiation and the P' elements' transposition is suggested.

Animals↗
PubMedDate not supplied

[Experience in using the surgical-orthodontic method proposed by V. V. Donskoĭ for treating mandibular fractures].

The author analyzes his experience gained in the treatment of 200 patients with mandibular corner and denture fractures by the orthodontic surgery method developed by V. V. Donskoĭ. Uni- and bilateral mandibular corner fractures made up 164 cases, the rest were combined injuries to the corner on the one side and to the body or condyle on the other side. 195 patients were operated under conduction analgesia when sitting in the dental chair and in the rest 5 cases condyle osteosynthesis was carried out on the one side and Donskoĭ's osteosynthesis on the other side under general anesthesia. Surgical procedure did not differ from that described earlier. Kirschner's pin, annealed [correction of preburnt] to make it less elastic, was horizontally inserted into the mandibular branch at the level of the posterior dental necks through a mucosal puncture and then shaped to match mandibular denture and fixed to the teeth with wire ligatures. Mandibular traction was carried out for 3-7 days, if necessary. The mean patient's stay in hospital made up approximately 22.7 days, total number of invalidity days 30.1. Infectious inflammatory complications were recorded in 9 patients. The advantages of the described method are discussed and recommendations on its practical use are given.

Adolescent↗
PubMedDate not supplied

[A method for bone suture of the mandible].

A technique of mandibular osteosynthesis with a bone suture is described, consisting in the formation of 2 pairs of through holes close to the fracture plane and fixation of fragments with a thread drawn alternately through the upper pair of holes and, after a preliminary crossing on the internal surface of the bone and overlapping the lower edge of the mandible, through the lower pair of holes. The horizontal portion of thread passing longitudinally between the upper holes is entrapped with one of the thread ends, then the thread is stretched tight and its ends are tied. A wire may be used as suture material. This technique was used in the treatment of 38 patients.

Humans↗
PubMedDate not supplied

[A new method of dental splinting].

A wire splint and the technique of its application for jaw immobilization is described. Stainless steel wires 0.7 to 1 mm in diameter are used to form the smooth and looplike parts applied to dentition in such a manner that loops be located closer to gingival margin and smooth part be situated in the vicinity of incisive margins of the teeth. Usually, the smooth part is an extension of looplike part of the splint and serves to embrace the lateral teeth into the splint. Both ends of the smooth part can be twisted together. The results of clinical application of the splint are compared to most common techniques and suggest major advantages of the novel splint.

Dental Occlusion↗