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At least 487 records · Page 27Linked to original sources
PubMed2005

Detection of a novel dystrophin gene mutation through carrier analysis performed during prenatal diagnosis in a case with intragenic recombination.

OBJECTIVES: To report a multi-technical approach to Duchenne muscular dystrophy (DMD) mutation testing through carrier analysis, in the prenatal diagnosis of a male foetus without a known mutation segregating in the family and with inconclusive results of linkage analysis. METHODS: Haplotype analysis with the DMD region markers for assigning the carrier status of the mother and for prenatal diagnosis of foetal DNA; semiquantitative multiplex analysis of maternal and foetal DNA for the promoter and for 34 exons of the DMD gene; sequencing analysis of the maternal and foetal DNA for confirmation of the results. RESULTS: Because of an intragenic recombination of the DMD gene in foetal DNA, haplotype analysis gave inconclusive results. Semiquantitative PCR analysis displayed a pattern compatible with a heterozygous exon 60 mutation in the mother's DNA, while foetal DNA showed a normal migration pattern. Sequencing analysis confirmed the presence of a novel 7 base-pair deletion in exon 60 of the DMD gene in the mother and excluded the deletion in the foetus. CONCLUSION: Semiquantitative PCR results allowed the DMD mutation detection in the mother and the exclusion in the foetus, showing its crucial importance in prenatal diagnosis in those cases where linkage analysis is not conclusive.

DNA Mutational Analysis↗
PubMed2003

Distinct mechanisms mediate the initial and sustained phases of cell migration in epidermal growth factor receptor-overexpressing cells.

Elevated levels of epidermal growth factor receptor (EGFR) are predictive of increased invasion and metastasis in many human cancers. In the present study, we have shown that two distinct pathways regulate cell migration in EGFR-overexpressing invasive cells such as MDA 468 breast cancer cells: mitogen-activated protein kinase (MAPK or ERK 1 and 2) pathways play a major role in early stages to cell migration; and protein kinase C delta isoforms (PKC-delta) play a significant role in later stages of sustained cell migration. Inhibition of MAPK activity with MAP kinase kinase (MEK) inhibitor PD98059 blocks early stages of cell migration (up to 4 h); however, cells revert back to enhanced cell migration after 4 h. While inhibition of PKC-delta activity with rottlerin or dominant-negative PKC-delta expression blocks sustained cell migration after 4 h and up to 12 h, the combination of MAPK and PKC inhibitors completely blocked transforming growth factor alpha (TGF-alpha)-induced cell migration in EGFR-overexpressing breast cancer cells. However, inhibition of MAPK activity completely blocked cell migration in low EGFR-expressing non-invasive breast cancer cells such as MCF-7 cells. Forced overexpression of EGFR in MCF-7 cells (EGFR/MCF-7 cells) resulted in cell migration patterns seen in MDA 468 cells, that is, MAPK pathways play a major role in early stages to cell migration, and PKC-delta plays a major role in later stages of sustained cell migration. The above data demonstrate that EGFR-overexpressing invasive cells have the ability to compensate the loss of MAPK-mediated signaling through activation of PKC-delta signaling for cell migration, which plays a major role in invasion and metastasis. In addition, data suggest that inhibition of MAPK and PKC-delta signaling pathways should abrogate cell migration and invasion in EGFR-overexpressing human breast cancer cells.

Breast Neoplasms↗
PubMed1993

A geographic analysis of non-Russian minorities in Russia and its ethnic homelands.

"The paper...analyzes the characteristics of 27 million non-Russians who constituted 18 percent of the population of the Russian Federation and its 31 ethnic homelands in 1989. Utilizing data from all Soviet censuses (from 1926), it reviews long-term historical trends; growth patterns related to urban-rural differences, family size, regional contrasts in rates of natural increase, and specific ethnic traits; migration patterns; factors influencing language shifts to the Russian; effect of location inside or outside homeland; and the influences of transportation, cities, and economic development in individual homelands."

Communication↗
PubMed2002

Moving around in a worm: netrin UNC-6 and circumferential axon guidance in C. elegans.

How does an extracellular guidance molecule direct multiple growth cones to different positions? The answer is important for understanding the development of complex neural connections. UNC-6 is a member of the netrin family of guidance proteins. It has phylogenetically conserved domains that mediate its different guidance and branching activities. In the Caenorhabditis elegans embryo, UNC-6 is secreted ventrally and a pattern of circumferential axon tracts develops as pioneer growth cones bearing UNC-5 and UNC-40 receptors are directed towards, or away from, the ventral sources. Following the first migrations, UNC-6 from additional sources allows more complex migration patterns to emerge. In addition, at specific dorsoventral positions, locally restricted extracellular molecules alter growth cone responses to UNC-6, causing circumferentially migrating growth cones to turn and longitudinal nerves to develop. These observations show that extracellular guidance molecules can direct complex arrangements of migrating growth cones in vivo by eliciting different types of responses, by spatially and temporally regulating their expression and by working in concert with other extracellular molecules.

Animals↗
PubMed2004

Decrease of parafollicular thyroid C-cells in experimental esophageal atresia: further evidence of a neural crest pathogenic pathway.

Adriamycin-induced experimental esophageal atresia (EA) is often associated with malformations of neural crest (NC) origin, such as abnormal pharyngeal pouch derivatives like the thymus and the parathyroids. The aim of the present study was to examine whether NC-derived thyroid C-cells were abnormal in a rat model. Pregnant rats received intraperitoneally either 2 mg/kg Adriamycin (EA) or vehicle (controls) on days 8 and 9 of gestation. Fetuses were recovered on day 21, and blocks including the trachea and thyroid were fixed in formalin, coronally sectioned at 3-mum widths, and stained with standard hematoxylin and eosin until the largest area of thyroid was reached. From this point on, the 1st, 10th, and 20th slices were immunohistochemically stained with anti-calcitonin antibody. Positively-stained cells in each section of the gland were counted using a computer-assisted image analysis method, and the results were averaged. The distribution of the cells within the gland was assessed as well. Comparisons between EA and control rats were made by nonparametric tests with a significance threshold of p<0.05. The number of C-cells was dramatically reduced in EA animals compared with controls (32.4+/-36 vs. 92.3+/-60.5, p<0.001). Histology of the thyroid was similar in both groups, but the distribution of positive C-cells within the gland followed an abnormal pattern in EA rats. Adriamycin causes a pattern of NC-derived malformations, including a severe decrease in thyroid C-cells accompanied by abnormal distribution or migration patterns. These results represent further evidence of the involvement of NC organogenic control dysregulation in the pathogenesis of EA and its associated malformations. The similarities between the rat model and the clinical picture strongly support investigating other subclinical NC-derived anomalies in patients with EA.

Animals↗
PubMed2006

A mutation in factor I that is associated with atypical hemolytic uremic syndrome does not affect the function of factor I in complement regulation.

Factor I (FI) is the major complement inhibitor that degrades C3b and C4b in the presence of cofactors such as factor H (FH) and membrane cofactor protein (MCP). Recently, mutations and polymorphisms in complement regulator molecules FH and MCP but also in FI have been associated with atypical hemolytic uremic syndrome (aHUS). HUS is a disorder characterized by hemolytic anemia, thrombocytopenia and acute renal failure. In this study, we report three unrelated patients with an identical heterozygous mutation, G261D, in the FI heavy chain who developed severe aHUS at different time points in their lives. Two of the patients also have polymorphisms in FH previously associated with risk of developing aHUS. Testing in particular one patient and control serum samples we did not observe major differences in complement hemolytic activity, FI plasma levels or the capability to degrade C4b or C3b. A recombinant protein was produced in order to analyze the functional consequences of the mutation. Mutant FI had a slightly different migration pattern during electrophoresis under reducing conditions. An alteration due to alternative splicing or glycosylation was ruled out, thus the altered migration may be due to proximity of the mutation to a cysteine residue. The recombinant mutant FI degraded C3b and C4b in a manner comparable to wild-type protein. In conclusion, despite the association between the heterozygous mutation in FI and aHUS we did not observe any abnormalities in the function of FI regarding complement regulation.

Adult↗
PubMed1995

Chemical selectivity in micellar electrokinetic chromatography: characterization of solute-micelle interactions for classification of surfactants.

The influence of surfactant type on migration behavior and chemical selectivity in micellar electrokinetic chromatography (MEKC) is investigated through linear solvation energy relationships (LSER) and functional group selectivities. In LSER modeling, solutes' capacity factors are correlated with their structural descriptors such as size, dipolarity, and hydrogen-bonding abilities. Using the LSER methodology, useful information about the nature of solute interactions with different types of surfactant aggregates can be obtained since capacity factor in MEKC is directly related to solute distribution between the bulk aqueous solvent and micelles. High correlations were observed for different LSER models of migration behavior in MEKC for a group of 60 uncharged aromatic compounds of non-hydrogen bonding (NHB), hydrogen-bonding acceptor (HBA) bases, and hydrogen-bonding donor (HBD) acids. In two anionic, hydrocarbon micellar systems of sodium dodecyl sulfate (SDS) and sodium cholate (SC), retention is primarily influenced by the size of molecules and their hydrogen bond accepting basicity. Their dipolarity/polarizability and hydrogen bond donating acidity play minor roles. Capacity factors of solutes in SDS and SC systems increase with their size and decrease for stronger hydrogen bond acceptor bases. These results are similar to those observed for other systems where hydrophobic interactions play a major role, e.g., solute distribution in the 1-octanol-water solvent system or retention in reversed phase LC. In MEKC with an anionic fluorocarbon surfactant, lithium perfluorooctanesulfonate (LiPFOS), however, size and solute HBD acidity are the two predominant factors. The LSER results indicate that compounds find the SDS micellar environments slightly less cohesive (i.e., more apolar) than the SC micelles, while the LiPFOS micelles are the most cohesive among the three surfactant aggregates and 1-octanol provides the least cohesive environment. The fluorocarbon micelles of LiPFOS, on the other hand, are the strongest hydrogen bond donor acids, followed by SDS, SC, and 1-octanol, respectively. The SC micelles have the most hydrogen bond acceptor basic characteristics, followed by 1-octanol, SDS, and LiPFOS micelles. It can be concluded that selectivity differences between these surfactant types in MEKC is primarily due to hydrogen-bonding interactions rather than the dipolar interactions. Comparing the perfluorinated and the hydrocarbon surfactants, even solute size can play a role in selective migration patterns. In addition, information from polar and hydrophobic group selectivities confirm the LSER conclusions about the underlying interactions that control migration behavior and chemical selectivity in MEKC.(ABSTRACT TRUNCATED AT 400 WORDS)

Chromatography, Liquid↗
PubMed2005

Migration history, acculturation, and breast cancer risk in Hispanic women.

BACKGROUND: Migrant studies have shown that breast cancer risk increases in women who move from countries with low incidence rates to countries with high rates. We examined the influence of migration history and acculturation on breast cancer risk in Hispanic women ages 35 to 79 years. METHODS: In a population-based case-control study conducted in the San Francisco Bay Area, information on migration history, language usage, and other risk factors for breast cancer was collected through an in-person interview for 991 cases and 1,285 controls. RESULTS: Breast cancer risk was 50% lower in foreign-born Hispanics than U.S.-born Hispanics. Risk increased with increasing duration of residence in the United States, decreasing age at migration, and increasing acculturation. Among long-term foreign-born residents, risk was lower among Hispanics who moved to the United States at age > or =20 years and those who spoke mostly Spanish. The difference in risk between third-generation or higher-generation Hispanics and recent migrants from rural areas was approximately 6-fold in postmenopausal women and 4-fold in premenopausal women. Adjustment for differences in the distribution of breast cancer risk factors greatly attenuated the associations with migration patterns in premenopausal women; reduced risks remained only in those who resided in the United States for <10 years or migrated at age > or =30 years. In postmenopausal women, a 25% to 30% lower risk remained among long-term residents and those who migrated to the United States before age 20 years. CONCLUSIONS: These findings suggest the importance of yet unidentified protective factors among both recent premenopausal migrants and postmenopausal migrants.

Acculturation↗
PubMed1980

Patterns of Sardinian migration.

In the first part of this paper, the authors trace "the history of Sardinian migration from the late nineteenth century to the present time. In the second part an attempt is made to test some of the hypothesized causes of migration. Census variables related to these causes and to the spatial pattern of migration are identified and analysed by the technique of stepwise multiple regression." The analysis, based on data for communes, covers the inter-censal period 1961-1971. The emphasis is on out-migration

Demography↗
PubMed2006

The evolution of genetic topologies.

This manuscript explores the simultaneous evolution of population genetic parameters and topological features within a population graph through a series of Monte Carlo simulations. I show that node centrality and graph breadth are significantly correlated to population genetic parameters Phi(ST) and M; (rho=-0.95;rho=-0.98, respectively), which are commonly used in quantifying among population genetic structure and isolation by distance. Next, the topological consequences of migration patterns are examined by contrasting N-island and stepping stone models of gene movement. Finally, I show how variation in migration rate influences the rate of formation of specific topological features with particular emphasis to the phase transition that occurs when populations begin to become fixed due to restricted movement of genes among populations. I close by discussing the utility of this method for the analysis of intraspecific genetic variation.

Biological Evolution↗
PubMed1997

Microgel electrophoresis: sensitivity, mechanisms, and DNA electrostretching.

Based on the treatment of microgels to remove proteins, we speculate that proteins may be bound to DNA in the microgels even after electrophoresis. We speculate that some DNA single-strand breaks may be a reflection of these protein-DNA complexes. We suggest methods to limit such artifacts, and present data demonstrating a lymphocyte DNA double-strand break sensitivity of 12.5 rads and day-to-day reproducibility of microgel electrophoresis using these principles. Extending these principles, we describe DNA behavior during alkaline and neutral microgel electrophoresis based on observations of the stained DNA and its migration patterns. During microgel electrophoresis, individual DNA molecules behave as if anchored at one end while the other end is free to migrate in response to the electric field. We capitalize on this behavior by developing a neutral microgel method to stretch chromosomes.

DNA Damage↗
PubMed2002

Cell movement patterns during gastrulation in the chick are controlled by positive and negative chemotaxis mediated by FGF4 and FGF8.

During gastrulation in amniotes, epiblast cells ingress through the primitive streak and migrate away to form endodermal, mesodermal, and extraembryonic structures. Here we analyze the detailed movement trajectories of cells emerging at different anterior-posterior positions from the primitive streak, using in vivo imaging of the movement of GFP-tagged streak cells. Cells emerging at different anterior-posterior positions from the streak show characteristic cell migration patterns, in response to guidance signals from neighboring tissues. Streak cells are attracted by sources of FGF4 and repelled by sources of FGF8. The observed movement patterns of anterior streak cells can be explained by an FGF8-mediated chemorepulsion of cells away from the streak followed by chemoattraction toward an FGF4 signal produced by the forming notochord.

Animals↗
PubMed1994

Cell viability and migration in nerve isografts and allografts.

Even though autogenous nerve grafts are used frequently, there is little information concerning cell survival rates and migration patterns, following peripheral nerve grafting. Labeling techniques with a vital fluorescent stain (PKH-26, Zynaxis Cell Science, Malvern, PA) allow cell migrations from both the nerve graft and host nerve to be tracked for up to 45 days from the time of nerve transplantation. With this labeling technique, two phases of nerve graft incorporation were identified, early and late, in an animal model using inbred Lewis and Brown-Norway rats. In genetically identical Lewis rats, isografts were performed as a means of modeling the autografts used clinically. At approximately 3 days after isogeneic transplantation, with the proximal host nerve end labeled, there was an early migration of host cells from the proximal nerve end into the epineural tissue of the nerve graft. At 25 days, a late phase was evident, with fluorescent labeling of host cells into the perineural and endoneural tissues. When the nerve grafts were labeled, the label persisted for up to 45 days, indicating viability of the graft. Cells migrated from the labeled nerve graft into the distal host nerve segment. Cellular migration from peripheral nerve tissue, following allograft transplantation, was initially similar to the isograft studies. But after 25 days, with the proximal host nerve end labeled, a significant decrease in the labeled host cells migrating into the graft was noted (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1999

Gene genealogies in geographically structured populations.

Population genetics theory has dealt only with the spatial or geographic pattern of degrees of relatedness or genetic similarity separately for each point in time. However, a frequent goal of experimental studies is to infer migration patterns that occurred in the past or over extended periods of time. To fully understand how a present geographic pattern of genetic variation reflects one in the past, it is necessary to build genealogy models that directly relate the two. For the first time, space-time probabilities of identity by descent and coalescence probabilities are formulated and characterized in this article. Formulations for general migration processes are developed and applied to specific types of systems. The results can be used to determine the level of certainty that genes found in present populations are descended from ancient genes in the same population or nearby populations vs. geographically distant populations. Some parameter combinations result in past populations that are quite distant geographically being essentially as likely to contain ancestors of genes at a given population as the past population located at the same place. This has implications for the geographic point of origin of ancestral, "Eve," genes. The results also form the first model for emerging "space-time" molecular genetic data.

Genealogy and Heraldry↗
PubMed1984

Demographic consequences of migration trends in Puerto Rico: 1950-1980.

"This paper examines the evolution and changes in migration patterns [in Puerto Rico] through the 1970's based on data from the 1980 census. The focus is on demographic consequences of migration, particularly with regard to population growth, redistribution and changing age structure." A final section is concerned with the socioeconomic implications of migration. (summary in FRE, SPA)

Age Distribution↗
PubMed1980

Re-evaluation of the lymphocyte migration through the high-endothelial venules. Light and electron microscopic studies on the opossum's lymph node.

We have described two types of lymphocyte migration through the HEV. In the first case the lymphocytes do not show constriction ring during the diapedesis. 97% of lymphocytes migrate in this manner. In this migration pattern the lymphocyte gets through the endothelium by means of flexibility and pliability of the endothelium. It is suggested that these lymphocytes migrate into the blood from the lymph node. In the second case the lymphocytes undergo morphological changes, they form constriction ring and they migrate from the blood into the lymph node.

Animals↗
PubMed1998

Immunological characterization of adenosine A2A receptors in human and porcine cardiovascular tissues.

Antipeptide antibody was raised in rabbit against the sequence (361-390) of RDC-8, the presumed adenosine A2A receptor cDNA from canine. The antibody titer was estimated by solid phase radioimmunoassay. Western blot analysis under reducing conditions identified a major 45 +/- 1 kDa protein in bovine striatal membranes. This immunoreactive band was competed in the presence of excess peptide. Furthermore, the antibody recognized a single 45-kDa immunoreactive band in membranes from cells transfected with the recombinant human adenosine A2A receptors, whereas, fail to cross-react with membranes from cells transfected with recombinant rat A1 and human A3 receptors. Membranes from human and porcine coronary artery, ventricle, atria and platelets (human only) showed a major immunoreactive band at 45 +/- 1 kDa size. Under nonreducing conditions, the migration patterns of the immunoreactive bands were not altered indicating the absence of interchain disulfide bond. The 45-kDa immunoreactive band co-migrated with 2-[4-(2-¿2-[(4-aminophenyl)methylcarbonylamino]ethyl-aminocarbo nyl¿et hyl)phenyl]ethylamino-5'-Nethylcarboxamidoadenosine photoaffinity labeled A2A adenosine receptor using SANPAH as the photoaffinity cross-linker. We provide immunological evidence for the presence of A2A adenosine receptor in human cardiovascular tissues that exists as a 45-kDa monomeric protein. This study also presents evidence for the presence of A2A adenosine receptor in ventricle and atria in both human and porcine.

Adolescent↗
PubMedDate not supplied

Genetic typing of Corallium rubrum.

Corallium rubrum taxonomy is based on morphologic criteria; little is known about its genome. We set up a rapid, easy method based on amplified fragment length polymorphism to characterize the genetic patterns of C. rubrum in an attempt to understand better the evolutionary relations between species from diverse geographic areas and to help define migration patterns. Applying this procedure to C. rubrum specimens from Spain and Italy, we identified 6 AFLP amplification fragments common to the 4 coral populations studied and 4 fragments that differentiated between these populations. Using this characterization we were able to plot a "genetic identity card" of this commercially harvested species, which is also a marker of pollution.

Animals↗