[Mutational level of translocated variants of Down's syndrome in Leningrad (1982-1991)]. / Mutatsionnyi uroven' translokatsionnykh variantov sindroma Dauna v Leningrade (1982-1991).

Karyological study of 644 newborns with Down's syndrome (DS) revealed 37 translocation cases (5.7%). Translocations were inherited in 8 cases, in 17 cases they were sporadic, and in 12 cases parents were not examined. Total mutation rate per gamete per generation (2.7.10) and mutation rates of D/21 and G/21 translocations in different female age groups were calculated. The obtained data are in good agreement with results of research in other world regions. Literature data on the parental origin of de novo translocations for DS are presented. The role of meiotic coorientation of nonhomologous chromosomes in anomalies of spermatogenesis is discussed.

[Polymorphism of C-heterochromatin chromosome regions in the etiology of human aneuploidy]. / Polimorfizm C-geterokhromatinovykh raionov khromosom v étiologii aneuploidii u cheloveka.

Cytogenetic study of the C-heterochromatic polymorphisms in 202 individuals from the Down's syndrome families and in 31 control individuals was undertaken. In 58 families the source of an additional chromosome was taken into account. It was shown that in the donors of extra chromosome, due to nondisjunction in the Ist meiotic division, the frequency of heteromorphism was higher (0.61) than in other groups: donors with the 2nd meiotic nondisjunction (0.44), partners of donors (0.48) and controls (0.46). Also, increase in heteromorphism rate was found in a group of young mothers (0.56) compared with a group of old mothers (0.45). The role of heterochromatic regions in chromosome nondisjunction is discussed from the point of view of meiotic nonhomologues coordination.

A repetitive DNA element, associated with telomeric sequences in Drosophila melanogaster, contains open reading frames.

He-T sequences are a complex repetitive family of DNA sequences in Drosophila that are associated with telomeric regions, pericentromeric heterochromatin, and the Y chromosome. A component of the He-T family containing open reading frames (ORFs) is described. These ORF-containing elements within the He-T family are designated T-elements, since hybridization in situ with the polytene salivary gland chromosomes results in detectable signal exclusively at the chromosome tips. One T-element that has been sequenced includes ORFs of 1,428 and 1,614 bp. The ORFs are overlapping but one nucleotide out of frame with respect to each other. The longer ORF contains cysteine-histidine motifs strongly resembling nucleic acid binding domains of gag-like proteins, and the overall organization of the T-element ORFs is reminiscent of LINE elements. The T-elements are transcribed and appear to be conserved in Drosophila species related to D. melanogaster. The results suggest that T-elements may play a role in the structure and/or function of telomeres.

An eclectic DNA structure adopted by human telomeric sequence under superhelical stress and low pH.

We have found, with the aid of 2-D gel electrophoresis, that double-stranded human telomeric repeat, (T2AG3)12.(C3TA2)12, being cloned within a plasmid, forms a protonated superhelically-induced structure. Experiments on chemical and enzymatic probing also indicate that the human telomeric repeats adopt an unusual structure. We have proposed an eclectic model for this structure in which four different elements coexist: a non-orthodox intramolecular triplex stabilized by the canonical protonated C.G*C+ base-triads and highly enriched by noncanonical base-triads; the intramolecular quadruplex formed by a portion of the G-rich strand; the single-stranded region encompassing a portion of the G-rich strand and, probably, the (C,A)-hairpin formed by a portion of the C-rich strand.

He-T family DNA sequences in the Y chromosome of Drosophila melanogaster share homology with the X-linked stellate genes.

The genome of Drosophila melanogaster contains a class of repetitive DNA sequences called the He-T family, which is unusual in being confined to telomeric and heterochromatic regions. The specific He-T fragment designated Dm665 was cloned in yeast by selection for an autonomously replicating sequence (ARS). Dm665 contains a restriction fragment length polymorphism (RFLP) that is specific to males and thus derives from the Y chromosome. Deletion mapping using X-Y translocations indicates that sequences homologous to Dm665 occur in at least one major cluster in each arm of the Y chromosome. Among 20 yeast artificial chromosome (YAC) clones containing Drosophila sequences homologous with Dm665, four clones derive from defined regions of the long arm of the Y and two from the short arm. The sequence of Dm665 is 2443 bp long, consists of 59% A + T, and contains no significant open reading frames or direct or inverted repeats. However, Dm665 contains a region of 650 bp that shares homology with portions of the X-linked locus Stellate.

[Hoppel-family of mobile elements of Drosophila melanogaster, flanked by short inverted repeats and having preferential localization in the heterochromatin regions of the genome]. / Hoppel-semeistvo mobil'nykh élementov Drosophila melanogaster, flankirovannoe korotkimi invertirovannymi povtorami i imeiushchee aredpochtitel'nuiu lokalizatsiiu v geterokhromatinovykh oblastiakh genoma.

A mobile element (ME) having 91% homology with Dm1360 (Kholodilov et al., 1987) has been cloned from the Drosophila melanogaster genome and sequenced. The family of ME was designated hoppel. The members of this family are flanked by short inverted repeats likewise P, hobo and HB. The hoppel is hybridized with 10-30 euchromatic sites of polytene chromosomes of different Drosophila stocks. Abundant hybridization with heterochromatic regions of chromosomes-chromocenter, pericentric heterochromatin, the 4 chromosome and telomeres was observed in all stocks of D. melanogaster examined and in D. simulans. At least six genomic variants of ME differing in length of the central part were revealed. Hoppel possesses ARS activity similar to the P element. Two ME hoppel were shown to be arranged as a direct repeat in the recombinant phage.

[A family of repeated sequences in Drosophila genome with telomeric localization: properties and polymorphism]. / Semeistvo povtoriaiushchikhsia posledovatel'nostei genoma drozofily, imeiushchee telomernuiu lokalizatsiiu: svoistva i polimorfizm.

The previously cloned Drosophila genome fragment Dm665 (2.4 kb) hybridizing with telomers on polytene chromosomes is a representative of the family of repeats, a part of which being organized in tandem clusters. The repeats are not transcribed in cell culture, are species-specific and represented in 200-250 copies per haploid genome. In natural and laboratory Drosophila lines polymorphism has been revealed with regard to homology with Dm665 in the telomeres.

[Changes in the intervertebral disks in disorders of segmental blood supply of the spine]. / Izmenenie mezhpozvonochnogo diska pri narushenii segmentarnogo krovosnabzheniia pozvonochnika.

In 50 mature Chinchilla rabbits a model of chronic insufficiency of blood supply in the lumbar vertebral bodies has been disturbed as a result of unilateral sectioning of the segmentary arteries and veins. By means of light and transmissive electron microscopy the dynamics of structural changes has been followed in tissue of the intervertebral discs for 3 months after the operative intervention. Under hypoxia in the ground substance of the pulposus++ nucleus even proteoglycans granular-filamentous network gradually develops and floccular material and transverse striated filamentous aggregates are accumulated. Notochord cells are subjected to certain degenerative changes and die. Simultaneously fibroblastic cells of the pulposus++ nucleus periphery become activated, they produce glycosaminoglycans and collagen. As a result the hydrated tissue of the pulposus++ nucleus is substituted for a newly formed fibrous cartilage. The process of fibroses in the intervertebral disc is completed in 3 months after blood circulation has been disturbed in the vertebral bodies.

[Extra- and intraorganic blood channel of the rabbit lumbar vertebrae in health and after cutting the segmentary arteries and veins]. / Ekstra- i intraorgannoe krovenosnoe ruslo poiasnichnykh pozvonkov krolikov v norme i pri pererezke segmentarnykh arterii i ven.

Extra- and intraorganic blood bed of the lumbar vertebrae has been investigated by means of the cast method and vital injection of the vessels with Indian ink-gelatin mixture and subsequent serial translucent preparations. Existence of constant topographo-anatomical relations has been stated between the segmentary arteries and veins with the lumbar vertebrae. Peculiarities in spatial organization of the microcirculatory bed have been revealed in different zones of the vertebral body, as well as peculiarity of blood supply of the epiphyseal osseous marginal plate. Topography and localization of changes in the intraorganic vertebral blood bed have been studied under conditions of bilateral crossing of the segmentary vascular fasciculi at the level of one, two and three vertebrae. Compensatory resources of the vertebral column blood bed are discussed, when large extra-organic trunks in the lumbar part are damaged.

[Congenital partial gigantism of the upper extremities in children]. / Vrozhdenyi chastichnyi gigantizm verkhnikh konechnostei u detei.

Angio-and phlebography, as well as pathomorphological studies were made on epiphyseal cartilaginous plate, diaphyseal bone tissue and skin of patients with partial gigantism of upper extremities. Significant developmental anomalies were found in the formation of palmar arches and digital arteries, as well as hypoplasia and aplasia of deep brachial and antebrachial veins. Light and electron microscopy revealed epiphyseal plate dystrophy and dysplasia, tubular bone osteoporosis, subcutaneous fat hyperplasia. The data obtained suggest a pathogenetic relationship between the vascular formation and the development of some malformations and growth abnormalities of upper extremities.

[Vascular and microscopic changes in hip joint tissues in Perthes' disease]. / Sosudistye i mikroskopicheskie izmeneniia v tkaniakh tazobedrennogo sustava pri bolezni Pertesa.

Electron-microscopic and angiographic studies of hip joints (healthy and sick) were performed. Bone-cartilaginous tissue and tissue of a joint capsula from 14 patients (7 to 14 years old) obtained during the operation were studied; angiography was performed in 6 patients during their life. Degenerative processes with a predominance of a hydropic dystrophy develop in the joint cartilage of the femur head. Collagen structures undergo mucoid swelling and dysproteinosis. Edema of the joint capsula, mainly its deep layers, is characteristic for this disease. Pathomorphological changes develop against the background of a vascular deficiency.

[Characteristics of bone tissue of rats after flight aboard biosputnik Kosmos-1129]. / Kharakteristika kostnoi tkani krys posle poleta na biosputnike "Kosmos-1129".

Bones of rats flown for 19 days onboard Cosmos-1129 were examined. The examination included bone mass, density, mineral composition, reconstruction parameters, and elemental composition at R + 1, R + 6, and R + 29. After flight the rats developed osteoporosis in the spongy structures of tubular bones and a smaller thickness of the cortical layer of the diaphysis; they showed no mineralization of the microstructures, a slight decrease of the Ca concentration, and a normal content of P. At R + 6 these changes progressively developed and at R + 29 they returned to normal.

[Ultrastructure of the contact surfaces of joints]. / Ul'trastruktura trushchikhsia poverkhnostei v sustave.

Scanning and transmissive electron microscopy of the rubbing surfaces in the human and rabbit knee joints has demonstrated that on the articular cartilage and meniscus there is a globular layer bordering the articular cavity. The globules are round, 500-1,200 nm in the diamter. The size of the globules and their arrangement density are not constant. Small globules (less than 100 nm) occur more often near the collagenous fibrillae of the sublayer. Large globules (up to 2,800 nm) are ball-shaped or flattened and found in aged persons.

[Dysplastic changes in the development of bone tissue in congenital pseudarthrosis]. / Displaticheskie narusheniia razvitiia kostnoi tkani pri vrozhdennykh lozhnykh sustavakh.

Angiographic examinations of shin blood vessels were carried out in 11 patients of 2 1/2 to 16 years with congenital false joints, and in 3 of these patients also pathomorphological and ultrastructural studies of the bone and cartilage tissue from the false joint area were performed. The deepest disorders of the blood supply were found at the level of the false joint. Dysplastic changes in the bone consisted in disorders of normal osteogenesis and atypical development of the cartilage, thinning of the bone structures, ultrastructural invalidity of osteocytes and insufficient mineral saturation of the organic matrix. Dystrophy of chondrocytes and deficient ultrastructure of collagen fibrills were noted.

[Osteoporosis in the absence of support for the extremity]. / Osteoporoz pri otsutstvii opory konechnosti.

In dogs, the lower part of the right extremities was amputated, thus generating a support-free state of the femur. On day 90 after the amputation bone resorption reached a high level and by the end of the year declined. The mature bone microstructures showed a higher degree of mineralization, whereas the young bone microstructures which were in predominance in the support-free femur displayed a lower degree of mineralization. In bone, the content of Ca decreased, that of K increased, while the content of Na and P remained unchanged. The development of osteoporosis in the support-free femur did not involve only quantitative variations in the mineral component.

[Structural and functional characteristics of the intervertebral disks of infants in the 1st year of life]. / Strukturno-funktsional'naia kharakteristika mezhpozvonochnykh diskov detei pervogo goda zhizni.

By means of the transmissive microscopic method, rearrangement of the intervertebral discs (ID) has been studied in children at early postnatal period, with special reference to changes in physiological loading on the spinal column when the infant acquires vertical position. Due to substitution of the fibroblastic cells by the cartilaginous ones with an active synthesis of glycosamineglycans and their secretion into the ground substance, hydration and turgor of the nucleus pulposus are provided. By the end of the first year, an initial stage of the collagenous fibrils formation can be observed in the nucleus pulposus. During the first months, cellular composition of the ID is essentially changed. In all parts of the disc the number of actively secreting cells is increasing. Tissue consolidation, increasing volume of the fibrous ring and turgor of the hydrated nucleus pulposus ensure increasing loading on the spinal column at the child's walking.