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PubMed1990

Genomic organization of the mouse pore-forming protein (perforin) gene and localization to chromosome 10. Similarities to and differences from C9.

Genomic clones encompassing the entire coding region of the mouse lymphocyte pore-forming protein gene (Pfp) have been isolated and used to determine its intron-exon organization. In contrast to C9, Pfp has a simple structure, consisting of only three exons (two of which encode polypeptide), a large 5' intron, and a single, smaller intron that is situated approximately one-third of the way through the protein-coding portions of the gene. The regions encoding the homologous domains of PFP and C9 are encoded on exons 7, 8, 9, and 10 of C9, but form only approximately half of the open reading frame of exon III in Pfp. Although encoding polypeptides with related functions, the two genes possess such sharply contrasting structures as to suggest that their analogous regions may have risen independently, by a process of convergent evolution. Using a panel of somatic cell hybrid cell lines, Pfp has been mapped to chromosome 10.

Amino Acid Sequence↗

PubMedDate not supplied

[Description of palpebral involvement in Fraser's syndrome].

GOAL: Fraser's syndrome is a rare multiple malformation involving the eyes, with cryptophthalmos. In its complete form, cryptophthalmos is a serious malformation with absence of eyelids and palpebral fissure. A review of ophthalmological signs is presented. CASE REPORT: A case of Fraser's syndrome is presented. Ophthalmological and somatic examination as well as evolution are described. RESULTS: Incomplete cryptophthalmos with symblepharon and bilateral palpebral coloboma are present. Surgical treatment with palpebral reconstruction allowed preservation of visual acuity in one eye. DISCUSSION: Ophthalmological signs are present in 93% of cases. Eyelid involvement such as symblepharon, and partial or complete coloboma are relatively frequent, whereas cryptophthalmos in its complete form are much more rare. CONCLUSION: Treatment involves palpebral reconstructive surgery in order to preserve visual function.

Abnormalities, Multiple↗

PubMed1994

The axio-somatic model in embryonic and tumoral development.

The growth and evolution of human tissues observed in embryogenesis and neoplasia are both reduced to a cellular theoretical axio-somatic model. The unlimited expansion and phenotype change of the model, are assured by the continuous generation of new cellular mitotic phenotypes which are grafted in a sequential order. Neogeneration results from the interaction between two cells of specific origins and situations: (a) axial cells of actual germ cell origin, generators and vectors of mitotic potential, (b) mitotically exhausted somatic cells of distal phenotypes, involved in meiotic recombinations, generating potential of neodifferentiation. The potentialities of both, axis and soma, are transformed by 'fertilization' in effectively growing new mitotic phenotypes. Bi-potent differentiation of germ line derived cells in gametopoiesis and haematopoiesis, is the source of the axial phenotype, identified in tissues as specific acid fast 'lymphoid' cells and/or vectors, formed by highly condensed hyperchromatinic nuclei and/or micronuclei endowed with DNAs of centromeric and kinetochoric types, wrapped in ceramide rich photo-affinity biomembranes.

Cell Differentiation↗

PubMed1996

[Criteria for somatization studied in an outpatient clinic for general internal medicine].

OBJECTIVE: To compare the evolution of bodily symptoms and the frequency of medical consultation using three different operational definitions of 'somatization'. DESIGN: Descriptive follow-up study. SETTING: General Internal Medicine Outpatient Clinic of Leiden University Hospital, the Netherlands. METHOD: Information about physical and psychic symptoms and about the somatic-medical diagnosis was collected in a group of 158 newly referred patients. The concept of 'somatization' was operationalized in three ways: a) seeking medical consultation for somatically unexplained symptoms; b) seeking medical consultation for somatically unexplained symptoms combined with an anxiety disorder or a depressive disorder according to the 'present state examination'; c) seeking medical consultation for somatically unexplained symptoms combined with a somatization disorder or hypochondria according to the Diagnostic and statistical manual of mental disorders (DSM) III R criteria. After a follow-up period of 1.2 years, information was collected from the entire study group about the evolution of the physical symptoms and the frequency of medical consultation. RESULTS: Patients with somatically unexplained symptoms combined with a somatization disorder or hypochondria were characterized in the follow-up by numerous physical symptoms and a high frequency of medical consultation. Compared with the other patients with unexplained symptoms, they visited the general practitioner during the follow-up period 2.5 times as often, saw specialists twice as often and were admitted to a 'somatic' hospital, 6 times as often. CONCLUSION: Using criteria of low restrictiveness for somatization, a large group of patients were identified with a relatively normal (average) illness behaviour. Using more restrictive criteria led to identification of a smaller group with more extreme illness behaviour.

Adult↗

PubMed2000

Using antibody catalysis to study the outcome of multiple evolutionary trials of a chemical task.

Catalytic aldolase antibodies generated by immunization with two different, but structurally related, beta-diketone haptens were cloned and sequenced to study similarities and differences between independently evolved catalysts. Kinetic and sequence analysis coupled with mutagenesis, structural, and modeling studies reveal that the defining event in the evolution of these catalysts was a somatic mutation that placed a lysine residue in a deep, yet otherwise unrefined, hydrophobic pocket. We suggest that covalent chemistries may be as readily selected from the immune repertoire as the traditional noncovalent interactions that have formed the basis of immunochemistry until this time. Further, we believe that these experiments recapitulate the defining events in the evolution of nature's enzymes, particularly as they relate to chemical mechanism, catalytic promiscuity, and gene duplication.

Amino Acid Sequence↗

PubMed1997

p53 mutations in breast cancer: incidence and relations to tumor aggressiveness and evolution of the disease.

Breast cancer is a polymorphic disease and, until now, nodal invasion and steroid receptor levels remain the most powerful and widely used prognostic indicators. Molecular oncology has proven the importance of somatic genetic events in cancer genesis and evolution. In breast cancer a number of genetic aberrations have been proposed to bear impact on disease outcome. Greatest significance has been associated to ERBB2 amplification and overexpression. More recently p53 mutations have been suggested to bear meaning in terms of cancer evolution. We discuss here the molecular epidemiology of p53 mutations in human breast tumors and the clinico-pathological significance that can be associated to them.

Breast Neoplasms↗

PubMed1986

Mechanisms of DNA sequence amplification and their evolutionary consequences.

DNA sequence amplification is a phenomenon that occurs predictably at defined stages during normal development in some organisms and has been shown to occur spontaneously, but sporadically, in a variety of cells, including mammalian cells, selected for overproduction of a gene product. Developmentally programmed gene amplification includes rDNA amplification during oögenesis in amphibia, chorion protein gene amplification in Drosophila and the chromosomal changes accompanying macronuclear formation in ciliates. Selected gene amplification is illustrated by mutant mammalian cells which have been selected in vitro or in vivo for the overproduction of a gene product. In these cells the unit of DNA that is amplified is much larger than the gene under selection, and appears to be formed by multiple recombination events, which bring together sequences not normally adjacent to each other. Often the product of amplification can be seen microscopically as aberrant chromosome forms. The vast majority of DNA amplification events occur in somatic nuclei, and thus would not have any direct effect on the evolution of a genome. However, the ability to amplify DNA in somatic cells does have consequences for the composition of the genomes of the organisms in which it can occur, and should DNA amplification occur, even sporadically, in germ-line cells the potential effect on evolution would be great.

Amphibians↗

PubMed1999

Heritable germ and somatic cell lineage competitions in chimeric colonial protochordates.

Theories of evolution that state natural selection acts on individuals have been modified to include multiple levels of selection. Here we demonstrate in chimeric protochordates that primitive germ cell (pgc) and somatic cell (psc) lineages have traits that also make them likely units of natural selection. Specifically, by using microsatellites to determine the genetic identity of various somatic and gametic tissues within vascularly fused Botryllus schlosseri chimeras, we show that genetically distinct pgc and psc can compete for access to developing gonads and somatic organs, and that this competition is hierarchical, reproducible, and heritable. Given that a single, highly polymorphic locus (Fu/HC) controls whether two contacting colonies fuse or reject, our findings also support a leading hypothesis for why the highly polymorphic histocompatibility loci common to many metazoa may have arisen or been maintained: to limit supercompetitor lineages to histocompatible kin.

Animals↗

PubMed1992

Evolutionary somatic cell changes in cervical tumour progression quantitatively evaluated with morphological, histochemical and kinetic parameters.

The somatic cell changes which characterise malignancy evolution in human cervical preneoplastic and neoplastic lesions have been assessed on histological sections by means of a computerised image analyser. Many features have been simultaneously measured on each cell of the lesions studied, and the following results have been obtained: Some features, mainly kinetic, show continuously increasing values which express changes correlated to the increasing malignancy; other features, especially related to nuclear atypia, cellular heterogeneity and the degree of aneuploidy, have values dropping at the level of early stromal infiltration, which can be morphometrically characterised as composed of relatively homogeneous phenotypes; these features seem to express the degree of genetic instability and relate to the evolutionary somatic cell changes; tumour progression evolves through sequential discontinuous steps, each of them characterised by specific phenotypical features of the neoplastic cell population; the neoplastic cells in the foci of early stromal infiltration and vascular invasion, phenotypically more homogeneous than the parent cell populations of carcinoma in situ and infiltrating carcinoma, seem to possess a greater genetic stability.

Aneuploidy↗

PubMed1999

Evolution of antigen binding receptors.

This review addresses issues related to the evolution of the complex multigene families of antigen binding receptors that function in adaptive immunity. Advances in molecular genetic technology now permit the study of immunoglobulin (Ig) and T cell receptor (TCR) genes in many species that are not commonly studied yet represent critical branch points in vertebrate phylogeny. Both Ig and TCR genes have been defined in most of the major lineages of jawed vertebrates, including the cartilaginous fishes, which represent the most phylogenetically divergent jawed vertebrate group relative to the mammals. Ig genes in cartilaginous fish are encoded by multiple individual loci that each contain rearranging segmental elements and constant regions. In some loci, segmental elements are joined in the germline, i.e. they do not undergo genetic rearrangement. Other major differences in Ig gene organization and the mechanisms of somatic diversification have occurred throughout vertebrate evolution. However, relating these changes to adaptive immune function in lower vertebrates is challenging. TCR genes exhibit greater sequence diversity in individual segmental elements than is found in Ig genes but have undergone fewer changes in gene organization, isotype diversity, and mechanisms of diversification. As of yet, homologous forms of antigen binding receptors have not been identified in jawless vertebrates; however, acquisition of large amounts of structural data for the antigen binding receptors that are found in a variety of jawed vertebrates has defined shared characteristics that provide unique insight into the distant origins of the rearranging gene systems and their relationships to both adaptive and innate recognition processes.

Amphibians↗

PubMedDate not supplied

[Comparative double-blind study of bromazepam versus prazepam in non-psychotic anxiety].

The efficacy of bromazepam and prazepam for the different components of anxiety: inhibition, asthenia and somatisation is evaluated in a multi-centric, comparative and randomised study, conducted as double blind and in parallel groups in 159 adult patients showing a manifest anxiety according to the F.D.A. criteria. After a 7 day wash-out period, the patients receive either bromazepam in a 12 mg/d dose or prazepam in a 40 mg/d dose, over 4 weeks (D0-D28), then in a decreasing dose from D28 to D43; follow-up is carried out using the anxious inhibition scale W.P.2, auto-questionnaire A.D.A., the Hamilton anxiety scale and the Tyrer questionnaire (benzodiazepine withdrawal symptoms questionnaire). Patients are evaluated seven times during the study: at day 7 for inclusion, day 0 for randomisation, then day 7 and day 14 for following visits, at day 28 for efficacy and tolerance evaluation, and at day 50 for utilisation and withdrawal evaluation. The major efficacy criteria are the evolution of inhibition, asthenia and somatisation as compounds of anxiety respectively evaluated by W.P.2 scale, asthenic partial score of autoquestionnaire A.D.A. and somatic partial score of Hamilton anxiety scale. The analysis of results don't show any significant difference between the two groups on the evolution of the components asthenia and inhibition. However the evolution of the somatic component clearly makes a significant difference in favour of bromazepam. There is also a significant difference in terms of global anxiolytic action efficacy, in favour of bromazepam.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed2001

The targeting of somatic hypermutation closely resembles that of meiotic mutation.

We have compared the microsequence specificity of mutations introduced during somatic hypermutation (SH) and those introduced meiotically during neutral evolution. We have minimized the effects of selection by studying nonproductive (hence unselected) Ig V region genes for somatic mutations and processed pseudogenes for meiotic mutations. We find that the two sets of patterns are very similar: the mutabilities of nucleotide triplets are positively correlated between the somatic and meiotic sets. The major differences that do exist fall into three distinct categories: 1) The mutability is sharply higher at CG dinucleotides under meiotic but not somatic mutation. 2) The complementary triplets AGC and GCT are much more mutable under somatic than under meiotic mutation. 3) Triplets of the form WAN (W = T or A) are uniformly more mutable under somatic than under meiotic mutation. Nevertheless, the relative mutabilities both within this set and within the SAN (S = G or C) triplets are highly correlated with those under meiotic mutation. We also find that the somatic triplet specificity is strongly symmetric under strand exchange for A/T triplets as well as for G/C triplets in spite of the strong predominance of A over T mutations. Thus, we suggest that somatic mutation has at least two distinct components: one that specifically targets AGC/GCT triplets and another that acts as true catalysis of meiotic mutation.

Base Sequence↗

PubMed1995

Peripheral neurotoxicity of taxol in patients previously treated with cisplatin.

BACKGROUND: Taxol is a new anticancer drug that acts as a tubulin polymeration enhancer. Its major toxicities are myelosuppression, hypersensitivity, and mucositis, but it also induces peripheral nerve damage. The use of taxol has recently been proposed for platinum-resistant cancers, but in these cases there is a possibility of cumulative toxicity in the peripheral nervous system. METHODS: Twenty-two patients affected by a relapse of cisplatin-treated ovarian cancer were examined clinically and neurophysiologically to determine the evolution of taxol-induced peripheral somatic and autonomic neurotoxicity and the possible cumulative effect of a combination of taxol and cisplatin. Each patient was examined before, during, and after taxol treatment (using a dose of 135 or 175 mg/m2 in 3 hours every 3 weeks). RESULTS: No patients were excluded from the study because of unacceptable toxicities of any kind. The serial examinations demonstrated that taxol induced onset of (or worsening of preexisting) neuropathic symptoms and signs in almost all the patients. The features were those of a distal, symmetrical, sensory polyneuropathy due to an axonopathy. Motor nerves and the autonomic nervous system were unaffected. Taxol neurotoxicity appeared early in the course of the treatment (i.e., after three courses) and was not severely disabling. In most cases after the early onset of peripheral neuropathy, stabilization of this side effect occurred. CONCLUSIONS: Considering the low doses of taxol used in this study, the sensory nerve damage was unexpectedly severe. It appears that a cumulative, but not dose-limiting, neurotoxic effect occurs using taxol in patients previously treated with cisplatin.

Adult↗

PubMed1992

Transcription factors, translocations and haematological malignancies.

Haematological malignancies arise as a consequence of clonal evolution driven by an accumulation of somatic mutations. Many haematological malignancies are associated with chromosome translocations that have provided powerful tools for the identification of proto-oncogenes implicated in the pathogenesis of leukaemia/lymphoma. The recent characterisation of several translocation breakpoints associated with human haematological tumours has demonstrated that genes encoding transcription factors are frequently involved. Direct alteration of transcription factor activity by somatic mutation may represent a particularly powerful leukaemogenic event.

Gene Expression Regulation, Leukemic↗

PubMed2002

Wolbachia density and virulence attenuation after transfer into a novel host.

The factors that control replication rate of the intracellular bacterium Wolbachia pipientis in its insect hosts are unknown and difficult to explore, given the complex interaction of symbiont and host genotypes. Using a strain of Wolbachia that is known to over-replicate and shorten the lifespan of its Drosophila melanogaster host, we have tracked the evolution of replication control in both somatic and reproductive tissues in a novel host/Wolbachia association. After transinfection (the transfer of a Wolbachia strain into a different species) of the over-replicating Wolbachia popcorn strain from D. melanogaster to Drosophila simulans, we demonstrated that initial high densities in the ovaries were in excess of what was required for perfect maternal transmission, and were likely causing reductions in reproductive fitness. Both densities and fitness costs associated with ovary infection rapidly declined in the generations after transinfection. The early death effect in D. simulans attenuated only slightly and was comparable to that induced in D. melanogaster. This study reveals a strong host involvement in Wolbachia replication rates, the independence of density control responses in different tissues, and the strength of natural selection acting on reproductive fitness.

Adaptation, Physiological↗

PubMed1983

Acquired alpha-thalassemia in preleukemia is due to decreased expression of all four alpha-globin genes.

A somatic mutation(s), acquired during the evolution of preleukemia in a 75-year-old Caucasian male of North European origin, resulted in a marked decrease in alpha-globin mRNA. The small amount of alpha-globin mRNA present in bone marrow cells was normally processed, had a normal (alpha 1/alpha 2)-globin mRNA ratio, and was translated normally. No detectable zeta-globin mRNA was found. The alpha- and zeta-globin genes were both hypomethylated and restriction endonuclease maps of the alpha- and zeta-globin genes were comparable in the patient's marrow and fibroblast DNA. The data are most consistent with the acquisition of a mutation(s) that resulted in decreased expression of all four alpha-globin genes.

Aged↗

PubMed2001

Human T-cell leukemia virus type 1 receptor expression among syncytium-resistant cell lines revealed by a novel surface glycoprotein-immunoadhesin.

The envelope glycoproteins of human T-cell leukemia virus type 1 (HTLV-1) perform functions that are crucial for virus entry into cells. The surface glycoprotein (SU) is responsible for viral recognition of, and binding to, target cells through its interaction with an unknown cell surface receptor. To facilitate molecular analysis of the receptor-binding properties of SU and to characterize the cellular receptor employed by HTLV-1, we have expressed a recombinant SU fused to the Fc domain of human immunoglobulin G. Here, we demonstrate that this novel SU-immunoadhesin retains both the biochemical properties of Fc and the receptor-binding specificity of the HTLV-1 SU. We use this SU-immunoadhesin to demonstrate, by direct cell surface binding assays, that the receptor used by HTLV-1 has been conserved through vertebrate evolution. Moreover, using murine-human somatic cell hybrids we provide data that do not support the previously assigned location for the HTLV-1 receptor on human chromosome 17. Most importantly, we show that many cell lines that are resistant to HTLV-1 envelope-mediated infection and syncytium formation express functional receptors that are recognized by the HTLV-1 SU. Based on our results, we suggest that for some HTLV-1-resistant cell lines the block to viral entry occurs at a late post-receptor-binding step of the entry process. Our findings will be of value in developing new strategies to identify the cellular receptor used by HTLV-1.

Animals↗

PubMed1984

Transformation of the Hprt gene with DNA from spermatogenic cells. Implications for the evolution of X chromosome inactivation.

DNA-mediated transformation of hypoxanthine guanine phosphoribosyl transferase (HPRT)-deficient cells was used to assess the state of the chromosome Hprt gene in spermatogenic cells. It had been shown previously that DNA from the inactive X chromosome of somatic cells functions poorly or not at all in HPRT transformation, indicating that DNA modification is involved in somatic cell X chromosome inactivation (XCI). In contrast, DNA from mature sperm does function in HPRT transformation suggesting that DNA modification may not be the basis of XCI in mature sperm. In this paper, transformation of HPRT- mouse and hamster cells has been performed to test the nature of XCI during earlier stages of spermatogenesis. DNA from these developing murine germ cells was shown to be capable of HPRT transformation, extending the observation that XCI in sperm does not appear to involve a DNA modification. We also show here that DNA from mature sperm of marsupials functions in HPRT transformation, a result consistent with a role for sperm XCI in the evolution of somatic X inactivation.

Animals↗