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PubMed2002

Migrating transient bone marrow edema syndrome of the knee: MRI findings in a new case.

We report a case of transient bone marrow edema syndrome migrating within two different compartments of the same knee. This unusual pattern of migration of the marrow edema, which has been previously described only in three cases of transient osteoporosis, may raise the suspicion of an aggressive disease. Radiologists should be aware of this phenomenon in order to avoid an aggressive management of this self-limiting disease.

Bone Marrow Diseases↗
PubMed1997

Spatial chain patterns of intra-urban migration.

"This research analyzes quantitatively the track of individual chain-type migration of many residents to determine how they move in response to changes in their lives, i.e., whether there is spatial regularity on the chain patterns of intra-urban migration. The study area for this research is the industrial city of Yokkaichi, Japan. The study helps us to understand the state of intra-urban migration at the non-aggregate level for all residents during a 15-year period. Special attention is given to the age at which a resident relocates, and to the interval between two successive movements, i.e., the stationary period."

Age Factors↗
PubMedDate not supplied

Population growth, fertility, mortality and migration in drought prone areas in Ethiopia.

To assess the population dynamics of drought-prone communities, we investigated 605 households in the pastoralist Boran community of Dubluk and in the agricultural community of Elka, both located in southern Ethiopia. The age and sex composition of the population as well as records of births, deaths and patterns of migration were observed for 2 consecutive years. Repeated surveys of the same households revealed much higher rates for deaths and births than did cross-sectional surveys with a one-year recall period. Indirect mortality estimates showed that the under 5 years mortality rates (per 1000 births) were 135 in Dubluk and 219 in Elka. Highest crude death rates were observed in Elka during periods of meningitis and malaria epidemics. During the period of observation, death rates fluctuated to a greater extent than birth rates. Both communities had very high rates of natural increase: in Dubluk 39.0/1000 and in Elka 37.1/1000. In Dubluk, this rate was far higher than any previously recorded and may have indicated that fertility regulating mechanisms, traditionally inherent in the pastoralist social organization, had become weaker as part of cultural changes. Dubluk represented a semi-nomadic society with a moderately high mobility pattern. Peak periods of migration coincided with times of food scarcity in Elka.

Adolescent↗
PubMed1994

Primordial germ cell migration.

Primordial germ cells are migratory cells. They arise very early in embryogenesis and have a similar pattern of migration in Drosophila, Xenopus, chick and mouse. In each case the primordial germ cells associate with the developing gut from which they migrate to the gonads during organogenesis. Germ cells proliferate mitotically from the time they begin to migrate to the time they colonize the genital ridges. From the study of mouse primordial germ cells, we now know of a number of agents which affect primordial germ cell proliferation, migration and adhesion in vitro. More recently, we have studied the interactions between primordial germ cells and the cells and extracellular matrix molecules on their migratory route. By labelling germ cells in whole-mount preparations with an antibody to the germ cell marker SSEA-1, we have studied the spatial distribution of germ cells in situ using confocal microscopy. This study has revealed that germ cells link up with each other forming extensive networks during migration.

Animals↗
PubMed1982

Migration within the periphery: Haitian labor in the Dominican sugar and coffee industries.

"This article presents data on the employment of Haitian labor in the sugar and coffee sectors in the Dominican economy. The Haitian cyclical pattern of migration is related to the enclave pattern of development as it has occurred in the Dominican Republic. The common features of both coffee and sugarcane production which stimulate the reliance on cheap foreign labor are discussed."

Agriculture↗
PubMed1994

Growth hormone inhibits normal B-cell differentiation and neutrophils' chemotaxis in vitro.

In acromegalic patients we have previously described a low ability of B-lymphocytes to differentiate into plasma cells under PWM stimulation, and a decreased chemotaxis of polymorphonuclear leukocytes (PMN) towards N-formylmethionylphenilalanine (FMP). In this study we examined the effect of exogenous GH over these immune functions in normal cells. PMN were purified by dextran sedimentation, incubated with recombinant human GH (0 to 20 ng/ml) and subjected to stimulation with FMP. PBMC were cultured with or without PWM, in the presence of GH (between 0 and 100 ng/ml). Plasma cells were determined as hemolysis plaque forming cells and also by immunofluorescence. GH, in a dose-dependent way, decreased directed migration of PMN (5 ng/ml: 1.787 +/- 148 microns; 10 ng/ml: 1.581 +/- 221 microns; 20 ng/ml: 1.569 +/- 149 microns, all as mean +/- S.E.M.), when compared to similar values of untreated PMN (0 ng/ml 2.085 +/- 139 microns). GH treatment did not modify spontaneous migration. Net migration showed the same pattern as directed migration. GH decreased dose-dependently the PWM-driven differentiation of B-lymphocytes into plasma cells to 60% of the basal level. Although not significantly, GH tended to increase spontaneous B-cell differentiation. These results could account for the already described defect in B-cell differentiation and PWN chemotaxis in acromegaly, emphasizing the relationship between the endocrine and immune systems.

Adult↗
PubMedDate not supplied

Ethical concerns in nurse migration.

International nurse migration is natural and to be expected. Recently, however, those who have fostered nurse migration believe that it will solve nursing shortages in developed countries and offer nurse migrants better working conditions and an improved quality of life. Whether natural or manipulated, migration flow patterns largely occur from developing to developed countries. In this article, nurse migration is examined using primary health care (PHC) as an ethical framework. The unmanaged flow of nurse migrants from developing to developed countries is inconsistent with "health for all" principles. Removing key health personnel from countries experiencing resource shortages is contrary to PHC equity. Often, nurse migrants are placed in vulnerable, inequitable work roles, and employing nurse migrants fails to address basic causes of nurse shortages in developed countries, such as dissatisfaction with work conditions and decreased funding for academic settings. Nurse migration policies and procedures can be developed to satisfy PHC ethics criteria if they (1) leave developing countries enhanced rather than depleted, (2) contribute to country health outcomes consistent with essential care for all people, (3) are based on community participation, (4) address common nursing labor issues, and (5) involve equitable and clear financial arrangements.

Attitude of Health Personnel↗
PubMed2000

Neutrophil antigen 5b is carried by a protein, migrating from 70 to 95 kDa, and may be involved in neonatal alloimmune neutropenia.

BACKGROUND: Neutrophil antigen 5b has been described as involved in transfusion reactions and not in neonatal alloimmune neutropenia. CASE REPORT: Anti-5b was found in the serum of a mother of a persistently neutropenic newborn, who had several bacterial infections. The neutropenia responded to treatment with recombinant human granulocyte-colony-stimulating factor. Immunoprecipitation experiments performed with this and three other 5b antisera identified a protein, migrating from 70 to 95 kDa, as carrier of 5b. The observed pattern of migration may point to heavy glycosylation of this protein. RESULTS: Six 5b-negative donors were identified among 54 screened white donors, for a 5b gene frequency of 0.66. CONCLUSION: Alloimmunization to 5b in pregnancy is rare. In the patients with neonatal neutropenia analyzed in the last decade, this was the first case discovered.

Antigens↗
PubMed1998

Neural precursor cell chain migration and division are regulated through different beta1 integrins.

Proliferation and tangential migration of neural precursor cells are essential determinants of CNS development. We have established cell culture models of both these processes using neural precursor cells grown as neurospheres. The pattern of migration that we observe in these cells is homotypic and occurs in the absence of a glial or neuronal scaffold, and is therefore equivalent to that previously described as chain migration. To determine the role of integrins in proliferation and migration, we have analysed the expression pattern of integrins on neurosphere cells and then performed blocking peptide and antibody experiments. Neurosphere cells express five major integrins, alpha5 beta1, alpha 6Abeta1, alphav beta1, alphav beta5 and alpha vbeta8 and, in addition, express low levels of alpha 6Bbeta1. Chain migration is inhibited by blocking the alpha 6beta1 integrin. Proliferation, by contrast, is inhibited by blocking the other beta1 integrins, alphav beta1 and alpha5 beta1. These results show that integrins are important regulators of neural precursor cell behaviour, with distinct beta1 integrins regulating proliferation and migration. They also demonstrate a novel role for the alpha6 beta1 integrin in the cell-cell interactions underlying homotypic chain migration.

Animals↗
PubMed2002

Glacial-induced altitudinal migrations in Armeria (Plumbaginaceae) inferred from patterns of chloroplast DNA haplotype sharing.

In contrast to northern European areas where large-scale migrations occurred to recolonize territories after glacial periods, species in southern regions survived and diverged without large geographical displacements. As a result of the importance of orography in much of the southern areas, such displacements must have involved populations ascending or descending mountains. The present study provides support for glacial-induced altitudinal migrations from chloroplast phylogeographic patterns in Armeria (Plumbaginaceae) in southeast Spain. One hundred and five sequences of the trnL-F spacer were obtained from seven species. Fifteen different haplotypes were recognized, their genealogy was inferred, and associations with geography were explored using nested clade analysis. Seven instances were detected in which the same haplotype is shared by two or three species within a particular massif. In all the cases, at least one of the species involved displayed different haplotypes in other areas; in most, the haplotype shared is predominant either in one of the species involved or in the massif. These patterns of haplotype sharing strongly suggest horizontal transfer between species. In one of the massifs (Sierra Nevada) the three species involved in haplotype sharing (A. splendens, A. filicaulis ssp. nevadensis, A. villosa ssp. bernisii) occur at markedly different altitudinal belts. It is argued that altitudinal migrations within the contraction-expansion model provide the best explanation for the current pattern, and that at least in one case it resulted in the formation of a new hybrid taxon, A. filicaulis ssp. nevadensis.

Altitude↗
PubMed2006

Distinct mechanisms regulate hemocyte chemotaxis during development and wound healing in Drosophila melanogaster.

Drosophila melanogaster hemocytes are highly motile macrophage-like cells that undergo a stereotypic pattern of migration to populate the whole embryo by late embryogenesis. We demonstrate that the migratory patterns of hemocytes at the embryonic ventral midline are orchestrated by chemotactic signals from the PDGF/VEGF ligands Pvf2 and -3 and that these directed migrations occur independently of phosphoinositide 3-kinase (PI3K) signaling. In contrast, using both laser ablation and a novel wounding assay that allows localized treatment with inhibitory drugs, we show that PI3K is essential for hemocyte chemotaxis toward wounds and that Pvf signals and PDGF/VEGF receptor expression are not required for this rapid chemotactic response. Our results demonstrate that at least two separate mechanisms operate in D. melanogaster embryos to direct hemocyte migration and show that although PI3K is crucial for hemocytes to sense a chemotactic gradient from a wound, it is not required to sense the growth factor signals that coordinate their developmental migrations along the ventral midline during embryogenesis.

Actins↗
PubMed1978

Metropolitan deconcentration: subareal in-migration and central city to ring mobility patterns among southern SMSAs.

The analysis of in-migration streams and subareal residential mobility patterns for moves made between 1965 and 1970 in SMSAs in the East South Central and South Atlantic census divisions indicates that, despite their historical contexts, these metropolitan areas now show spatial differentiation patterns similar to those of the great cities of the Northeast. The white population has increased in ring areas primarily because of in-migration rates; the black population in the central cities has increased primarily because of in-migration rates to those subareas. Little variation in these patterns across SMSA size categories was apparent.

Black or African American↗
PubMed1997

Interactions of Eph-related receptors and ligands confer rostrocaudal pattern to trunk neural crest migration.

BACKGROUND: In the trunk of avian embryos, neural crest migration through the somites is segmental, with neural crest cells entering the rostral half of each somitic sclerotome but avoiding the caudal half. Little is known about the molecular nature of the cues-intrinsic to the somites-that are responsible for this segmental migration of neural crest cells. RESULTS: We demonstrate that Eph-related receptor tyrosine kinases and their ligands are essential for the segmental migration of avian trunk neural crest cells through the somites. EphB3 localizes to the rostral half-sclerotome, including the neural crest, and the ligand ephrin-B1 has a complementary pattern of expression in the caudal half-sclerotome. To test the functional significance of this striking asymmetry, soluble ligand ephrin-B1 was added to interfere with receptor function in either whole trunk explants or neural crest cells cultured on alternating stripes of ephrin-B1 versus fibronection. Neural crest cells in vitro avoided migrating on lanes of immobilized ephrin-B1; the addition of soluble ephrin-B1 blocked this inhibition. Similarly, in whole trunk explants, the metameric pattern of neural crest migration was disrupted by addition of soluble ephrin-B1, allowing entry of neural crest cells into caudal portions of the sclerotome. CONCLUSIONS: Both in vivo and in vitro, the addition of soluble ephrin-B1 results in a loss of the metameric migratory pattern and a disorganization of neural crest cell movement. These results demonstrate that Eph-family receptor tyrosine kinases and their transmembrane ligands are involved in interactions between neural crest and sclerotomal cells, mediating an inhibitory activity necessary to constrain neural precursors to specific territories in the developing nervous system.

Animals↗
PubMed1982

Volatility in the geographical structure of short-run US interstate migration.

"Migration is often thought to be a long-run phenomenon. However, it is shown here by means of labor-force migration estimates derived from the Continuous Work History Sample over the period 1958-1975, that US interstate migration is quite volatile over the short run with respect both to its adjustment to macroeconomic fluctuations and to its geographic structure. A hierarchical clustering routine is utilized to analyse yearly estimates of interstate gross in-migration and out-migration so as to identify the temporal stability and characteristics of the geographical patterns of migration. States enter the national migration linkage tree at different levels for different years, depending upon the level of short-run economic activity." It is also shown that "when national economic conditions worsen, labor-supply adjustments are more localized and the degree of interstate interdependence is less than in times of economic boom."

Americas↗
PubMed1984

Chemotactic behavior of myoblasts.

Earlier studies have suggested that myogenic cells of somite origin migrate into the developing limb, but little is known about the factors affecting the pattern of migration. In order to understand the migratory behavior of myogenic cells, embryonic skeletal muscle cells were tested for their ability to migrate chemotactically using a modified Boyden chamber assay system. It is shown here, for the first time, that embryonic skeletal muscle cells have the capacity to migrate toward a gradient of platelet-derived growth factor (PDGF) and PDGF-like factors present in serum and chick embryo extract (CEE). On the other hand, nonmyogenic limb mesenchyme cells do not exhibit such a response. A hypothesis is proposed here that chemotactic factors from the already patterned vasculature might influence the distribution of skeletal muscle cells during early limb development.

Animals↗