Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “structural variants”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,333 records · Page 74Linked to original sources
PubMedDate not supplied

[Ultrastructural organization of liposomes and isolated glycoproteins of enveloped viruses obtained by using the nonionic detergent MESK].

Materials on comparative ultrastructural analysis of isolated glycoproteins (GP) of influenza, parainfluenza, and Venezuelan equine encephalomyelitis viruses as well as liposomes reconstructed on their basis prepared with the use of MECK, a nonionic detergent, are presented. Original virions, subvirion particles, and isolated GP were characterized by typical morphology and remained intact in highly purified and concentrated suspensions owing to the use of the sparing and effective method of treatment with MECK. After removal of the detergent typical micellar aggregates were shown to form from GP monomers for all three viruses under study. The forming rosettes morphologically and biologically are similar to those isolated from ortho-, paramyxo-, and togaviruses using the Triton X-100 detergent. Stages of liposome formation and interaction with cell membrane were studied electron microscopically. A common feature for liposomes from GP of all the three viruses consisted in the formation of two morphological variants of structural complexes: filaments of various lengths and composition in them of GP and vesicles, the arrays of GP in which were similar or identical to those of viral membrane. Liposomes from Sendai virus GP possessed hemolytic activity, however, their interaction with the cell studied by means of the immunoferritine label occurred not by fusion but apparently as a result of destruction of the cell membrane at the sites of protein F contact with plasmalemma and formation in the latter of defects leading to erythrocyte lysis.

Animals↗
PubMed1973

The importance of the included serum proteins in the immune response in rabbits to a rat skin xenograft.

Various substances were isolated from rat skin including, protein-dermatan sulfate, certain other species of heavy and light protein-mucopolysaccharides, five electrophoretically separable nonstructural glycoproteins and a crude and two "purified" variants of structural glycoproteins. When the serum proteins contaminating these substances were removed as completely as possible, none of these produced an accelerated immune response to a rat skin graft in appropriately preimmunized rabbits, and none of those that were tested had a blocking effect on the immune response. On the other hand, the contaminated products and undenatured and denatured rat serum produced accelerated immune responses to a rat skin graft in appropriately preimmunized rabbits. These observations, together with those on skin reactions to the isolated products and to rat serum in rabbits sensitized by rat skin grafts, emphasize the importance of the included serum proteins in the immune response to this type of xenograft.

Adsorption↗
PubMed1982

Structure of amplified normal and variant dihydrofolate reductase genes in mouse sarcoma S180 cells.

We constructed a gene library from a murine cell line with amplified dihydrofolate reductase (dhfr) genes by inserting random segments of DNA into lambda Ch4A. From this library, the dhfr gene and 30 kilobase pairs of surrounding DNA were cloned, and the restriction map was determined. All of the coding regions were sequenced and show that the gene spans a total of 31 kilobase pairs and has five intervening sequences in the coding portion of the gene. In addition, two classes of variant dhfr genes were found in the amplified line, which were amplified and present at levels of 10 to 30% of the normal dhfr genes. Numerous repeated sequences were located throughout the gene region, some of which share homology with previously defied families of repeats.

Animals↗
PubMed1984

Molecular cloning of adeno-associated virus variant genomes and generation of infectious virus by recombination in mammalian cells.

Continued passage of the human parvovirus, adeno-associated virus (AAV), at high multiplicity of infection in human cells results in the accumulation of AAV particles containing variant genomes. We have analyzed the structure of individual variant AAV genomes by molecular cloning in the Escherichia coli plasmid, pBR328. Each of the AAV inserts in six individual recombinant plasmids contained a single internal deletion but in contrast to a previous model, the locations of the deletions were nonrandom. The molecular cloning protocol also generated recombinant plasmids containing the entire AAV2 DNA sequence which yielded infectious AAV particles when transfected into human 293 cells in the presence of helper adenovirus using a DEAE-transfection procedure. Infectious AAV genomes were also generated by recombination when cells were jointly transfected with a mixture of plasmids containing two different mutant AAV genomes. The efficiency of this recombination appear to be influenced by the degree of homology between the mutant AAV genomes.

Base Sequence↗
PubMed1984

[Possibilities of eradicating the persistent HBsAg carrier state].

Five HBsAg carriers were examined by clinical, biochemical, radionuclide, immunologic and histomorphologic methods. Different variants of structural and functional relations were established. Attempts were made to eradicate the persistent virus carrierstate with the aid of the antiviral drug virasol, the immunomodulating drug levamisole, nonspecific (BCG vaccine) and specific (original corpuscular vaccine against hepatitis B) immunostimulants. No positive therapeutic effect was obtained. The difficulties and possibilities of a further study into the title problem with due regard for integration mechanisms of infection and prospects of the effective prophylaxis of virus transmission from the mother to the child at birth are discussed.

Adult↗
PubMed1980

[Canine fibrinogen glycopeptides].

Canine fibrinogen was digested by a complex of proteases from Streptomyces griseus. The degradation products were purified by gel-filtration, DEAE-cellulose chromatography and electrophoresis, resulting in nine glycopeptides, eight of which contained aspartic acid and one--serine. The other amino acids were found only in trace amounts. The glycopeptides were shown to contain hexoamines, mannose, galactose and sialic acid. The oligosaccharide chains form a sequence of structurally similar variants. The individual microheterogeneity of canine fibrinogen with respect to carbohydrate chains was detected. A comparison of the carbohydrate composition of fibrinogen and glycopeptides suggests the presence of four carbohydrate chains in the protein molecule.

Amino Acids↗
PubMed1976

[Posttraumatic pyogenic and granulomatous encephalitis. An animal experimental contribution on inflammation (author's transl)].

The present studies were performed to elucidate the factors responsible for the relative resistance of the brain to bacterial infections. As a model, group A streptococci were used to produce an experimental brain infection in mice. Attention was focussed on the activity of brain macrophages, the function of which to date is poorly understood. The primary purpose of the experiments was to compare the types of inflammation elicited in the brain by the injection of either killed or living group A streptococci. As a result, two fundamentally different types of encephalitis were observed histologically. A granulomatous inflammation was induced by killed streptococci; when deposited in the brain by intracerebral injection, these were phagocytosed by invading mononuclear macrophages and polymorphonuclear granulocytes during the first day p.i. There was no necrosis of brain tissue excepting the stab wound at the site of injection. The number of granulocytes in the inflammatory infiltrates decreased during the first week p.i. whereas, during the same period, the number of macrophages forming granuloma-like cell accummulations increased. At the beginning of the third week a fading of the granulomatous encephalitis was observed. In contrast, living streptococci produced a pyogenic inflammation of the meninges as well as of the grey and white matter in the region of the stab wound combined with extended tissue necrosis surrounding deposits of bacteria. This pyogenic infection progressed until the end of the first week, forming a brain abscess. A phlegmonous spreading of the pyogenic inflammation predominantly in the white matter and pyocephalus internus was also observed. In contrast to the increase of mononuclear macrophages in the border zone of the abscesses, the granulocytic inflammation decreased. During the second and third weeks p.i. granulation tissue consisting of proliferating connective tissue cells, macrophages and lymphocytes replaced pyogenic necrosis. A secondary purpose was to determine the fate of living and killed streptococci within the pyogenic and granulomatous encephalitis. In these studies immunohistologic, electron microscopic, bacteriologic and serologic methods were employed in addition to the techniques already mentioned. In the majority of the experimental animals streptococci were killed by granulocytes within the first week after injection of the living bacteria. At this time, most of the streptococci were contained within granulocytes and macrophages located to the periphery of the brain abscesses. Corresponding to the granulomatous encephalitis produced by injection of killed streptococci it was possible to detect persistent cell wall material in macrophages by immunohistology. By electronmicroscopy streptococci and their cell walls were found within the phagocytic vacuoles of macrophages. During the course of degradation the group-specific cell wall carbohydrate was enzymatically converted into the group A-variant specific structure...

Animals↗
PubMedDate not supplied

[The multinucleate cells of the spermatogenic layer in rats as a criterion of hypoxic damage to the testis].

The formation and dynamics of transformations of multinucleated cells in the spermatogenic layer was studied in mature male albino rats in a model experiment with 10-12 min. long clinical death followed by revivification at different periods of the postreanimation period. The maximum formation of multinucleated cells is observed on the 2nd-3rd days after revivification, and further their occurrence becomes less. With an increase of degenerative alterations in the nuclei and cytoplasm of multinucleated cells, the latter become isolated from the spermatogenic layer causing disturbances of its structure. A variant with the multiple formation of multinucleated cells is described resulting in an injury of the spermatogenic layer at a considerable distance. A supposition is put forward of the relationship of the formation of multinucleated cells with the clonal syncytial principle of organization of the developing sex cells and the cycle of spermatogenesis. The appearance of multinucleated cells is an undoubtable indicator of degenerative alterations of the spermatogenic layer under conditions of hypoxia.

Animals↗
PubMed1993

[Pseudolesions in liver sonography].

Several common hepatic ultrasound pseudolesions are presented that may closely resemble pathological conditions. The majority of these pitfalls is caused by normal anatomic structures, anatomical variants of the liver or the perihepatic regions, and benign alterations of the echotexture of the liver. Exact knowledge and a precise scanning technique by an experienced sonographer are essential to avoid mistaking such findings for true liver disease. In some instances (especially when dealing with anatomical variants) computed tomography is also helpful.

Diagnosis, Differential↗
PubMed1996

Spermatogenesis in Drosophila.

A short summary on the present knowledge on spermatogenesis in Drosophila is given which also points out particular questions of interest in the context of this morphogenetic process. Such points of interest are the formation of lampbrush loops in primary spermatocytes, the chromosomal events during meiosis, the occurrence of chromatin rearrangements and the regulation of gene activities at the posttranscriptional level. The activities and some major conclusions from my laboratory are subsequently described. They include studies of the expression of histone variants, the structure and function of lampbrush loops and the expression of genes participating in sperm morphogenesis.

Animals↗
PubMed1996

The spectrum of beta-thalassemia mutations in Malays in Singapore and Kelantan.

The spectrum of beta-thalassemia mutations in Malays in Singapore and Kelantan (Northeast Malaysia) was studied. Allele specific priming was used to determine the mutations in beta-carriers at -28, Codon 17, IVSI #1, IVSI #5, Codon 41-42 and IVSII #654 along the beta-globin gene. The most common structural hemoglobin variant in Southeast Asia, Hb E, was detected by DNA amplification with restriction enzyme (Mnl1) analysis. Direct genomic sequencing was carried out to detect the beta-mutations uncharacterized by allele-specific priming. The most prevalent beta-mutations in Singaporean Malays were IVSI #5 (45.83%) followed by Hb E (20.83%), codon 15 (12.5%) and IVSI #1 and IVSII #654 at 4.17% each. In contrast, the distribution of the beta-mutations in Kelantan Malays differed, with Hb E as the most common mutation (39.29%) followed by IVSI #5 (17.86%), codon 41-42 (14.29%), codon 19 (10.71%) and codon 17 (3.57%). The beta-mutations in Kelantan Malays follow closely the distribution of beta-mutations in Thais and Malays of Southern Thailand and Malays of West Malaysia. The AAC-->AGC base substitution in codon 19 has been detected only in these populations. The spectrum of beta-mutations in the Singaporean Malays is more similar to those reported in Indonesia with the beta-mutation at codon 15 (TGG-->TAG) present in both populations. The characterization of beta-mutations in Singaporean and Kelantan Malays will facilitate the establishment of effective prenatal diagnosis programs for beta-thalassemia major in this ethnic group.

Alleles↗
PubMed1997

p53 mediates permanent arrest over multiple cell cycles in response to gamma-irradiation.

A new technique that monitors cell cycle progression over multiple cycles was used to gain insight into how p53 limits the emergence of variants with structural chromosome alterations following gamma-irradiation. G0-synchronized, p53+ (with a functional p53 pathway) normal human fibroblast and epithelial strains underwent a dose-dependent permanent arrest in the initial G0-G1 phase after irradiation. The dose-response curves indicate that a single event, such as an irreparable DNA break, may be sufficient to induce arrest. p53+ cells that escaped the initial G0-G1 phase after irradiation entered S phase in at least two waves. However, many of these cells underwent long-term arrest in subsequent phases. In contrast, virtually all of the cells in isogenic p53- (with a nonfunctional p53 pathway) strains escaped from the first G0-G1 phase without delay, regardless of the dose. p53- cells were also eliminated in subsequent phases but at significantly lower frequencies. Consistent with these findings, the reproductive viability of p53- cells was higher than p53+ cells. The nonclonogenic fraction appeared to be eliminated within three cycles for both cell types. In addition, artificial holding in G0 after irradiation, which allows for the repair of potentially lethal damage, led to similar increases in survival in p53+ and p53- cells. These data are inconsistent with the hypothesis that the primary function of p53-dependent G0-G1 arrest in response to gamma-irradiation is to allow additional time for DNA repair. Rather, they indicate that p53 helps maintain genetic stability by eliminating cells with damaged chromosomes from the reproductively viable population.

Apoptosis↗
PubMedDate not supplied

[Preventive measures for allergic diseases].

Allergic diseases, particularly asthma and asthma equivalents, are among the most frequent disorders seen in the pediatric clinic. Approximately 25% of children from developed countries have presented wheezing in recent years, and half of these children later experience major asthma attacks. Likewise, 25% of children between 8 and 11 years have at some time used beta agonists and at least 10% of them use preventive asthma medication. Prevention measures for allergic asthma include: 1) avoiding allergic sensitization; 2) avoiding the presentation of disease in sensitized patients; and 3) preventing symptoms after the disease has appeared. Allergic diseases have a multifactorial origin that includes genetic, perinatal, and specific and non-specific environmental factors. From a genetic point of view, asthma is a multifactorial and heterogeneous pathology with a variable degree of penetration and phenocopy. Allergy is more frequent among the offspring of atopic parents. Genetic variations in different chromosomes affect molecules and receptors involved in atopy: IgE elevation, Fce1 receptor and chromosome 11; IL-4 and chromosome 3; gamma interferon and chromosome 12; TcR a/d receptor and chromosome 14; TcR-beta and chromosome 7; and the main histocompatibility complex HLA I and II and chromosome 6. Likewise, it has been confirmed that genetic variants affect structures in the impact organs, such as the beta 2 receptors of IL-4 soluble receptors, which favor bronchial hyperreactivity. Recently, somatometric measures have been related (low weight and large head circumference at birth) with a later increase in IgE and the occurrence of asthma. The environmental factors most closely involved in the occurrence of asthma are: diet (early exposure to sensitizing foods); domestic, outside, and occupational seroallergens; pollution (particularly smoking and urban and industrial pollution); and infections, particularly viral infections. In the present study, the methods used for the early identification of children at risk are evaluated, as well as the role of the primary care pediatrician in the early detection of allergic children and the interventions that they carry out. Finally, an analysis is made of the preventive measures that should be taken in children at risk of allergic disease, particularly: 1) increasing awareness of health, 2) reduction of exposure to smoking. 3) reduction of urban and industrial pollution, 4) delayed introduction of certain foods, reduction in the level of domestic allergens, 6) control of infections, and 7) pharmacological measures designed to prevent the occurrence of asthma in children.

Adult↗
PubMed1999

Advances in indolo[2,3-a]carbazole chemistry: design and synthesis of protein kinase C and topoisomerase I inhibitors.

Indolo[2,3-a]carbazoles, their pyrrolo[3,4-c]anellated variants and structurally closely related bisindolylmaleimides represent a biologically highly interesting class of natural compounds which are potential anticancer agents. According to the ongoing literature new and efficient synthetic methods yield a great variety of these compounds which have been reported in detail. The biological activities and the inhibitory activities against the target enzymes protein kinase C and topoisomerase I are also discussed including structure activity relationships. A molecular binding model of the protein kinase C inhibitors with the target enzyme at the atomic level is presented and supported by X-ray crystallographic structures and by molecular modelling studies.

Antineoplastic Agents↗
PubMed1993

Prolactin variants in term and preterm human milk: altered structural characteristics, biological activity and immunoreactivity.

This study was undertaken to determine if PRL variants differing in structural characteristics as well as biological activity and immunoreactivity are present in human milk and to assess whether the physiological state of the mammary gland (premature initiation of lactation, progression of lactation) influences the forms or activity of human milk-borne PRL. Human milk samples were collected in early (day 1-5) or mature lactation (1-4 months) from women delivering term (T) or preterm (PT) infants. Milk was fractionated on Sephadex G-100, Concanavalin A-Sepharose, or Phosphogel to estimate molecular weight (MW), degree of glycosylated PRL(G), and degree of phosphorylated (P) PRL, respectively. Prolactin-like bioactivity (B) was measured by the PRL-dependent proliferation of the Nb-2 lymphoma cell and PRL-like immunoreactivity (I) by radioimmunoassay (RIA) using NIDDK reagents. Milk obtained from mothers of T infants contained significantly greater B than I-PRL at each stage of lactation (early: B = 132 +/- 13.9 P.E./ml, I = 83.43 +/- 12 P.E./ml, mature: B = 41.74 +/- 8.9 P.E./ml, I = 27.19 +/- 5.5 P.E./ml; P < 0.01-0.001). PRL-like bioactivity was greatest in early milk produced by mothers of T infants and declined as lactation progressed. No differences in B or I-PRL were evident for milk collected from mothers of preterm infants at any stage of lactation. In early lactation the PRL-like bioactivity of milk collected from mothers of T infants was significantly greater than in unfractionated milk collected from mothers of PT infants (P < 0.05). The number of PRL variants present in milk was characteristic of the stage of lactation and gestation (T early > PT early; T early > T mature). Early milk from mothers of T infants contained an average of 5 bioactive PRL variants, early milk from mothers of PT infants an average of 4 bioactive variants, and mature milk from mothers of T infants an average of 3 bioactive variants. The distribution of molecular weights associated with PRL variants in milk infranatant was variable among subjects within a specific stage of lactation/gestation. However, the representative range of molecular weights of PRL variants identified in milk sample was similar between groups (T early: < 8, 16, 20, 24, 25-28, 32, 42, > 66; PT early: 16, 20, 23, 25-28, 32, > 66; T mature: 20, 25-28, 32, 35, > 66).(ABSTRACT TRUNCATED AT 400 WORDS)

Breast↗