Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Minor: Evolution”

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 1,045 records · Page 58Linked to original sources
PubMed2001

Perinatal transmission of major, minor, and multiple maternal human immunodeficiency virus type 1 variants in utero and intrapartum.

Previous studies have provided conflicting data on the presence of selective pressures in the transmission of a homogeneous maternal viral subpopulation to the infant. Therefore, the purpose of this study was to definitively characterize the human immunodeficiency virus type 1 (HIV-1) quasispecies transmitted in utero and intrapartum. HIV-1 envelope gene diversity from peripheral blood mononuclear cells and plasma was measured during gestation and at delivery in mothers who did and did not transmit HIV perinatally by using a DNA heteroduplex mobility assay. Children were defined as infected in utero or intrapartum based on the timing of the first detection of HIV. Untreated transmitting mothers (n = 19) had significantly lower HIV-1 quasispecies diversity at delivery than untreated nontransmittting mothers (n = 18) (median Shannon entropy, 0.711 [0.642 to 0.816] versus 0.853 [0.762 to 0.925], P = 0.005). Eight mothers transmitted a single major env variant to their infants in utero, and one mother transmitted a single major env variant intrapartum. Four mothers transmitted multiple HIV-1 env variants to their infants in utero, and two mothers transmitted multiple env variants intrapartum. The remaining six intrapartum- and two in utero-infected infants had a homogeneous HIV-1 env quasispecies which did not comigrate with their mothers' bands at their first positive time point. In conclusion, in utero transmitters were more likely to transmit single or multiple major maternal viral variants. In contrast, intrapartum transmitters were more likely to transmit minor HIV-1 variants. These data indicate that different selective pressures, depending on the timing of transmission, may be involved in determining the pattern of maternal HIV-1 variant transmission.

Evolution, Molecular↗
PubMed1992

The riddle of the uvula.

Since ancient times, the uvula has been a subject of interesting and contradictory observations. On the one hand, it was regarded as having a functional role in speech and in immunology, but on the other hand it was regarded as a potentially hazardous organ, possibly responsible for sudden infant death syndrome. None of these hypotheses, however, has been proved. In a previous study on patients undergoing uvulopalatopharyngoplasty, we suggested that the most important function of the uvula is connected with the muscularis uvula. Its function could be related to drinking while bending over. This previous assumption was that the uvula is a phylogenetic remnant from mammals that drink while bending their neck downward. In the present study, the soft palate of eight different mammals was macroscopically and microscopically studied and compared. Of all animals in the study, a small underdeveloped uvula was found only in two baboons. We found that the human uvula consists of an intermix of serous and seromucous glandular masses, muscular tissue, and large excretory canals. The serous and seromucous glands are absent in the other mammals. Thus, the uvula is a highly sophisticated structure, capable of producing a large quantity of fluid saliva that can be excreted in a short time. Both uvula and speech serve to differentiate human beings from animals. Our conclusion is that the uvula is possibly an accessory organ of speech, and may be another marker of human evolution that differentiates man from other mammals.

Animals↗
PubMed2000

Hydrogen peroxide yields during the incompatible interaction of tobacco suspension cells inoculated with Phytophthora nicotianae.

Rates of H(2)O(2) production by tobacco suspension cells inoculated with zoospores from compatible or incompatible races of the pathogen Phytophthora nicotianae were followed by direct measurement of oxygen evolution from culture supernatants following catalase addition. Rates of HO(2)(*)/O(2)(-) production were compared by following the formation of the formazan of sodium, 3'-[1-[phenylamino-carbonyl]-3,4-tetrazolium]-bis(4-methoxy-6-nitro) benzene-sulfonic acid hydrate. In the incompatible interaction only, both reactive oxygen species (ROS) were produced by the cultured host cells in a minor burst between 0 and 2 h and then in a major burst between 8 and 12 h after inoculation. Absolute levels of H(2)O(2) could not be accurately measured due to its metabolism by host cells, but results are consistent with the majority of H(2)O(2) being formed via dismutation of HO(2)(*)/O(2)(-). The effects of inhibitors of endogenous Cu/Zn superoxide dismutase (diethyldithiocarbamate) and catalase (3-amino-1,2,4-triazole and salicylic acid) were also examined. Yields of ROS in the presence of the inhibitors diphenylene iodonium, allopurinol, and salicylhydroxamic acid suggest that ROS were generated in incompatible host responses by more than one mechanism.

Catalase↗
PubMed2002

Hypertransaminasemia in pediatric celiac disease patients and its prevalence as a diagnostic clue.

OBJECTIVES: The aims of this study were to evaluate the following: 1) the prevalence of hypertransaminasemia (HT) in a pediatric celiac disease (CD) and its relation with clinical parameters; 2) the frequency of HT as the only manifestation of pediatric CD; and 3) the evolution of HT after a gluten free diet. METHODS: A total of 114 consecutive pediatric CD patients were studied (60% with classical and 40% with atypical forms). Antiendomisyum antibodies and anti-tissue transglutaminase antibodies were determined in patients with a clinical suspicion of CD (including unexplained chronic HT), in patients at risk, and in patients with preoperative increased ALT activity for minor surgery. CD was confirmed by duodenal biopsy. At baseline, the relationship between clinical factors and aminotransferase status was univariately and multivariately assessed. After starting a gluten free diet, patients were followed up, until serological markers cleared and serum aminotransferase normalized. RESULTS: HT occurred in 32% of patients (37 of 114) at diagnosis. HT was the only manifestation of CD in five patients (4.3%). Patients with HT were younger (2.9 +/- 0.4 yr) than patients with normal aminotransferases (5.1 +/- 0.5 yr) (p = 0.007). A higher percentage of patients with classical CD tend to have abnormal aminotransferases (73%; 95% CI = 65-81%) than do patients with atypical CD (27%; 95% CI = 19-35%) (p = 0.068). Logistic regression analysis showed that only younger age was significantly associated with HT (p = 0.039; OR = 0.8; 95% CI = 0.71-0.99). Aminotransferases normalized with a gluten free diet in all 35 patients who were followed-up, either before (n = 18) or at the same time (n = 17) as serological markers cleared. CONCLUSIONS: HT is a frequent finding in pediatric CD patients and, in a substantial proportion, may be the only manifestation of CD. Thus, serological markers of CD should be introduced in the first step of the diagnostic workup of liver diseases in pediatric patients.

Adolescent↗
PubMed1994

Transcription of a variant human U6 small nuclear RNA gene is controlled by a novel, internal RNA polymerase III promoter.

Promoter elements in the 5' flanking regions of vertebrate U6 RNA genes have been shown to be both necessary and sufficient for transcription by RNA polymerase III. We have recently isolated and characterized a variant human U6 gene (87U6) that can be transcribed by RNA polymerase III in vitro in the absence of any natural 5' or 3' flanking sequences. This gene contains 10 nucleotide differences from the previously characterized human U6 gene (wtU6) within the coding region but has no homology to wtU6 in the upstream promoter region. By constructing chimeras between these two genes, we have shown that mutation of as few as two nucleotides in the coding region of the human U6 RNA gene is sufficient to create an internal promoter that is functional in vitro. A T-to-C transition at position 57 and a single T deletion at position 52 produce an internal U6 promoter that is nearly as active in vitro as the external U6 polymerase III promoter utilized by wtU6. Neither of these residues is absolutely conserved during evolution, and both of these nucleotide changes occur within the previously noted A box homology. Deletion and linker scanning mutations within the coding region of this variant U6 gene suggest that, in addition to the central region including bp 52 and 57, sequences at the extreme 5' end of the gene are critical for efficient transcription. In contrast, flanking sequences have a minor effect on transcriptional efficiency. This arrangement is unique among internal RNA polymerase III promoters and may indicate unique regulation of this gene.

Base Sequence↗
PubMed1990

The closely related Drosophila sry beta and sry delta zinc finger proteins show differential embryonic expression and distinct patterns of binding sites on polytene chromosomes.

Serendipity (sry) beta (beta) and delta (delta) are two finger protein genes resulting from a duplication event. Comparison of their respective protein products shows interspersed blocks of conserved and divergent amino-acid sequences. The most extensively conserved region corresponds to the predicted DNA-binding domain which includes 6 contiguous fingers; no significant sequence conservation is found upstream and downstream of the protein-coding region. We have analysed the evolutionary divergence of the sry beta and delta proteins on two separate levels, their embryonic pattern of expression and their DNA-binding properties in vitro and in vivo. By using specific antibodies and transformant lines containing beta-galactosidase fusion genes, we show that the sry beta and sry delta proteins are maternally inherited and present in embryonic nuclei at the onset of zygotic transcription, suggesting that they are transcription factors involved in this process. Zygotic synthesis of the sry beta protein starts during nuclear division cycles 12-13, prior to cellularisation of the blastoderm, while the zygotic sry delta protein is not detectable before germ band extension (stage 10 embryos). Contrary to sry delta, the zygotic sry beta protein constitutes only a minor fraction of the total embryonic protein. The sry beta and delta proteins made in E. coli bind to DNA, with partly overlapping specificities. Their in vivo patterns of binding to DNA, visualised by immunostaining polytene chromosomes, differ both in the number and position of their binding sites. Thus changes in expression pattern and DNA-binding specificity have contributed to the evolution of the sry beta and delta genes.

Animals↗
PubMed2003

Update on the therapeutic approaches to brain tumors.

Neuro-oncology is a rapidly growing field of study. The understanding of brain tumors has expanded in pace with advances in the field of molecular biology and genetics. Diagnoses are more accurate, biopsy and surgical intervention safer, radiotherapy more focused and chemotherapy safer and better tolerated. Novel strategies based on the understanding of brain tumor biology are emerging as targeted approaches to therapy. Despite all this, only a minority of patients with certain subsets of brain tumors have experienced prolonged survival. This review focuses on the standard and emerging therapies for the two most common categories of brain tumors: gliomas and meningiomas. Primary CNS lymphoma, while a relatively rare tumor, is also included as a topic of discussion as the achievements in its treatment represent the principal strides in the evolution of neuro-oncology.

Angiogenesis Inhibitors↗
PubMed1986

[Renal complications of anti-cancer chemotherapy].

This review is not intended as a complete study of the nephrotoxicity of chemotherapy agents used in the treatment of cancer. The number of these drugs that are cytotoxic has considerably increased in the last few years and our information is incomplete for many of them. We therefore reviewed the observations reported in the literature. Cis-platinum, streptozotocin, methotrexate at high doses, mithramycin and mitomycin are highly nephrotoxic. Other drugs, such as nitrosoureas, celiptium are less nephrotoxic while some appear to rarely induce nephrotoxicity. Anticancer drug nephrotoxicity is characterized by its particular insidiousness, its time of occurrence and its evolution. Since no clinical manifestations accompany the lesions, nephrotoxicity must be sought routinely. It can occur early or late, may be constant as of the first course or appear only after a certain cumulative dose and even occasionally after such a long interval that its cause may appear to be in doubt. The severity of this nephrotoxicity ranges from the usual first minor urinary anomalies to terminal renal failure. The pathophysiogenic mechanisms of the nephrotoxicity remain in most cases obscure. The mode of penetration into the cells is not known. There are fewer data on the interaction between the toxic agent and the cellular metabolism. In most cases, the drug itself in unchanged form does not seem to be the causative agent, which appears rather to be its metabolite. These metabolites are not always identified. Thus nephrotoxicity of antitumoral agents has not been given sufficient attention. Only better knowledge of their action within the kidney will eventually lead to progress in preventing their harmful side effects.

Alkylating Agents↗
PubMed1985

Hospice in the United States. Multiple models and varied programs.

This article has reviewed the evolution of hospice care as a discrete cluster of services in the United States from the mid-1960s until the early 1980s. It describes the psychosocial conditions produced by the dominance of cure-oriented medical technology in the medical care system and the reaction to them that hospice programs have come to express. The 6 major organizational models and their minor variations have been described, as were sources and methods of reimbursement until the implementation of the Medicare Hospice Benefit. Finally, the emergence of standards of care for this new service were outlined and the development of the JCAH Hospice Standards and Accreditation mechanism was emphasized.

Community Health Services↗
PubMed1998

[Salivary gland tumors. Apropos of 48 surgical cases].

The interest of tumors of salivary gland has increased according to the nosology, diagnosis and therapeutic aspects. This study object to appreciate the frequency of this pathology at the ENT Department of the University Hospital Center of Ouagadougou and to report our experience in their diagnostic and therapeutic management. We have collected 48 cases, representing 2% of the department surgery activity and 7% of the tumors operated between 1985 and 1996. This report has concerned 32 parotid tumors (66.7%), 10 submaxillary tumors (20.8%), 6 minor gland tumors (12.5%). This series was composed of 28 women and 20 men with an average age of 41 years. Diagnosis management was based on clinical, radiologic and echographic examination. The correlation between preoperative and histological diagnosis was correct in 88.7% cases. Benign tumors represented 83.3% of the cases with essentially pleomorphic adenomas, and the malignant tumors 16.7% cases. Post operative evolution was simple in 85.4% cases. After 3 years, local recurrence occurred in 4 cases. The prognosis of malignant tumors has been unsatisfactory: the survival rate at 3 years has been 20%.

Adenoma↗
PubMed1998

Evolution of peptides that modulate the spectral qualities of bound, small-molecule fluorophores.

BACKGROUND: Fluorophore dyes are used extensively in biomedical research to sensitively assay cellular constituents and physiology. We have created, as proof of principle, fluorophore dye binding peptides that could have applications in fluorescent dye-based approaches in vitro and in vivo. RESULTS: A panel of Texas red, Rhodamine red, Oregon green 514 and fluorescein binding peptides, termed here 'fluorettes', was selected via biopanning of a combinatorial library of 12-mer peptides fused to a minor coat pIII protein of the filamentous bacteriophage M13. The 'best' fluorette sequences from each of the groups were subjected to further mutagenesis, followed by a second biopanning to select a new generation of improved fluorettes. Phage were selected that had higher avidity for each fluorophore except Rhodamine red. Of these, peptides were characterized that could specifically and with high affinity bind at least one dye, Texas red, in solution. In addition, the binding of certain peptides to Texas red shifted the peak excitation and/or the emission spectra of the bound dye. CONCLUSIONS: Peptides in the context of phage display could readily be selected that could bind to small-molecule fluorophores. The affinities of selected mutant fluorettes could be increased by mutation and further selection. Only a subset of the free peptides could bind free dyes in solution, suggesting that phage context contributed to the selection and ability of certain peptidic regions to independently bind the dyes. Future screens might lead to the creation of other dye-binding peptides with novel characteristics or Texas red derivatives with cross-linking substituents might be designed to increase the utility of the system.

Amino Acid Sequence↗
PubMed1989

New evidence for trans-species evolution of the H-2 class I polymorphism.

A serological survey using alloantisera specific for the H-2 class I antigens in Japanese wild mice. Mus musculus molossinus, revealed a high frequency of the H-2Kf antigen. This antigen has also been found in European wild mice, M. m. domesticus and M. m. musculus. In this survey, the H-2Kf antigen was characterized through the use of ten newly isolated monoclonal antibodies raised against cells of a Japanese wild mouse, and by Southern blot analysis using an H-2K locus-specific probe which hybridizes with the 3' end of the gene. The serologically identified H-2Kf antigens revealed several minor variations in reactivities to the monoclonal antibodies. However, all the antigens examined could be clearly separated into two types with respect to the restriction fragment length polymorphism (RFLP) pattern. The first type, found together with a single, characteristic RFLP pattern, was always associated with the presence of reactivity to one particular monoclonal antibody MS54. The second type, found to represent different RFLP patterns, is associated with the absence of reactivity to MS54. This concordance between the presence of an antigenic determinant and a particular RFLP was observed not only within Mus musculus subspecies but also in a different species: M. spretus, carrying the same antigenic determinant, gave an identical RFLP to that of the other MS54-positive Mus musculus subspecies. The data suggest that the antigenic determinant specific for MS54 is an ancient polymorphic structure which has survived the long period of diversification of Mus species (approximately 2-3 million years) without alteration, and is associated with a stable DNA structure at the 3' end of the H-2K gene.

Animals↗
PubMed2006

Dynamic evolution at pericentromeres.

Pericentromeres are exceptional genomic regions: in animals they contain extensive segmental duplications implicated in gene creation, and in plants they sustain rearrangements and insertions uncommon in euchromatin. To examine the mechanisms and patterns of plant pericentromere evolution, we compared pericentromere sequence from four Brassicaceae species separated by <15 million years (Myr). This flowering plant family is ideal for studying relationships between genome reorganization and pericentromere evolution-its members have undergone recent polyploidization and hybridization, with close relatives changing in genome size and chromosome number. Through sequence and hybridization analyses, we examined regions from Arabidopsis arenosa, Capsella rubella, and Olimarabidopsis pumila that are homologous to Arabidopsis thaliana pericentromeres (peri-CENs) III and V, and used FISH to demonstrate they have been maintained near centromere satellite arrays in each species. Sequence analysis revealed a set of highly conserved genes, yet we discovered substantial differences in intergenic length and species-specific changes in sequence content and gene density. We discovered that A. thaliana has undergone recent, significant expansions within its pericentromeres, in some cases measuring hundreds of kilobases; these findings are in marked contrast to euchromatic segments in these species that exhibit only minor length changes. While plant pericentromeres do contain some duplications, we did not find evidence of extensive segmental duplications, as has been documented in primates. Our data support a model in which plant pericentromeres may experience selective pressures distinct from euchromatin, tolerating rapid, dynamic changes in structure and sequence content, including large insertions of mobile elements, 5S rDNA arrays and pseudogenes.

Arabidopsis↗
PubMed1987

Evolutionary changes in the developmental expression of silkmoth chorion genes and their morphological consequences.

Discrete changes in silkmoth choriogenesis have occurred during evolution, as exemplified in the present report in Antheraea polyphemus and Hyalophora cecropia. At the level of morphology, the chorion of A. polyphemus has surface structures, called aeropyle crowns, that are absent from H. cecropia. Aeropyle crowns form during the very late period of choriogenesis and consist of two substructures--lamellae and filler. Filler is present in H. cecropia in greatly reduced amounts. At the level of protein synthesis, overall similarities in the two species are maintained until the very late period of choriogenesis, when synthesis of aeropyle crown components is maximal. In H. cecropia, very late period-specific proteins are reduced in number and abundance. Several of these minor proteins are candidates for E1 and E2, the components of filler. E1 and E2 RNAs are about 35 times more abundant in A. polyphemus, despite very similar gene copy numbers and times of expression in the two species. These results support the hypothesis that evolutionary changes in chorion morphology have resulted from regulatory changes in the expression of chorion genes, either at the level of transcription or mRNA decay. The hypothesis that evolutionary changes in chorion morphology are based on terminal addition onto a preexisting developmental program is discussed.

Animals↗
PubMed1983

Comparison of the D-lactate stereospecific dehydrogenase of Limulus polyphemus with active-site regions of L-lactate dehydrogenases.

Lactate dehydrogenase (D-lactate:NAD+ oxidoreductase, EC 1.1.1.28) from the horseshoe crab, Limulus polyphemus, a dimeric enzyme stereospecific for D-lactate, has been purified by affinity chromatography. Maleyl tryptic peptides containing arginine residues isolated from the Limulus enzyme have been characterized and sequenced. The small peptides obtained from similarly treated L-lactate-specific enzyme homologs define major portions of the substrate and coenzyme binding regions and are virtually identical among L-lactate-specific enzymes. Although the six small peptides and free arginine isolated from the Limulus enzyme indicate that the small number of arginine tryptic peptides are located in a few discrete consecutive clusters similarly to the L-lactate dehydrogenases, the peptides nevertheless show no obvious sequence homology to the corresponding peptides from L-lactate dehydrogenases. These results indicate that this lactate dehydrogenase of altered substrate specificity either evolved with major rearrangements of the active site if it evolved from an L-lactate dehydrogenase, or that D-lactate dehydrogenases have evolved from a different protein. The results contradict proposed models which suggest that minor changes in the spatial orientation of pyruvate resulting from minimal rearrangement of the active site could accommodate the change in substrate specificity.

Amino Acid Sequence↗
PubMed1998

Extramedullary presentation of chronic myelogenous leukemia with p190 BCR/ABL transcripts.

We present here a rare case of Philadelphia chromosome (Ph)-positive chronic myelogenous leukemia having p190 BCR/ABL with a malignant clinical picture of extramedullary blast crisis at onset, followed by rapid evolution to bone-marrow blast crisis. The patient was a 44-year-old woman presenting with leukocytosis and multiple lymph-node swelling in the neck. Lymph-node biopsy revealed a myeloperoxidase-positive blastoma with cell-surface markers of myeloid and T-lymphoid lineages. Fluorescence in situ hybridization and the reverse transcription polymerase chain reaction detected a minor BCR breakpoint but failed to detect a major BCR breakpoint. By single-strand conformation polymorphism and direct sequencing, no alteration in the TP53 gene was found, and no additional chromosomal abnormalities other than Ph were identified. The present case suggests that p190 BCR/ABL is associated with the aggressive course of the disease.

Adult↗
PubMed2002

Emergence and selection of RNA virus variants: memory and extinction.

Two features of viral quasispecies are reviewed: the presence of memory genomes as minority components of their mutant spectra, and viral extinction due to enhanced mutagenesis. Memory has been documented with several genetic markers of the important animal picornavirus foot-and-mouth disease virus (FMDV). The presence of memory genomes in viral quasispecies may accelerate their adaptive response whenever a selective constraint has already been experienced by a viral population during previous stages of its evolution. Enhanced mutagenesis has been shown to lead to losses of infectivity of a number of RNA viruses: poliovirus, vesicular stomatitis virus, human immunodeficiency virus type 1 and FMDV. These observations, based on the theoretical prediction of the existence of a copying error-threshold for maintenance of genetic information, may contribute to the development of a new antiviral strategy.

Animals↗
PubMed2006

Recessive missense mutations in LAMB2 expand the clinical spectrum of LAMB2-associated disorders.

Congenital nephrotic syndrome is clinically and genetically heterogeneous. The majority of cases can be attributed to mutations in the genes NPHS1, NPHS2, and WT1. By homozygosity mapping in a consanguineous family with isolated congenital nephrotic syndrome, we identified a potential candidate region on chromosome 3p. The LAMB2 gene, which was recently reported as mutated in Pierson syndrome (microcoria-congenital nephrosis syndrome; OMIM #609049), was located in the linkage interval. Sequencing of all coding exons of LAMB2 revealed a novel homozygous missense mutation (R246Q) in both affected children. A different mutation at this codon (R246W), which is highly conserved through evolution, has recently been reported as causing Pierson syndrome. Subsequent LAMB2 mutational screening in six additional families with congenital nephrotic syndrome revealed compound heterozygosity for two novel missense mutations in one family with additional nonspecific ocular anomalies. These findings demonstrate that the spectrum of LAMB2-associated disorders is broader than previously anticipated and includes congenital nephrotic syndrome without eye anomalies or with minor ocular changes different from those observed in Pierson syndrome. This phenotypic variability likely reflects specific genotypes. We conclude that mutational analysis in LAMB2 should be considered in congenital nephrotic syndrome, if no mutations are found in NPHS1, NPHS2, or WT1.

Child, Preschool↗