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PubMed1989

Patterns of migration indicate sexual transmission of HTLV-I infection in non-pregnant women in Papua New Guinea.

The prevalence of infection with human T-cell leukaemia virus (HTLV-I) was studied in Madang Province on the north coast of Papua New Guinea. Serum specimens collected from non-pregnant women in 17 villages were tested for anti-HTLV-I by gelatin particle agglutination screening and confirmed by immunofluorescence and Western blotting. Overall, 13.9% of subjects were antibody-positive, with the prevalence of antibodies varying from less than 10% to 30% in villages situated less than 10 km apart. Two groups of migrant women were identified, and in both a parity-related increase in antibody prevalence which occurred only after marriage suggested that the predominant mode of transmission in migrant women was sexual. There was no parity-associated increase in anti-HTLV-I in indigenous women, and in contrast to migrant women, nulliparous indigenous women had a high prevalence of antibody (16.8% vs. 0%; p = 0.005). Vertical transmission cannot be excluded in indigenous women. No correlation was detected between the prevalence of anti-HTLV-I and a variety of indices of malarial infection.

Emigration and Immigration↗
PubMed1996

A comparison of the patterns of migration and the destinations of homotopically transplanted neonatal subventricular zone cells and heterotopically transplanted telencephalic ventricular zone cells.

The cells arising in the anterior part of the subventricular zone (SVZa) migrate along a well-demarcated pathway which lacks radial glial fibers to the olfactory bulb where they differentiate into interneurons of the granule cell layer or glomerular layer (Luskin, 1993, Neuron 11, 173). To analyze the mechanisms underlying this highly directed migration, we have compared the migratory behavior of unmanipulated SVZa-derived cells to that of homotopically transplanted SVZa cells and of heterotopically transplanted telencephalic ventricular zone (VZ) cells that ordinarily migrate in association with radial glial fibers. To identify the phenotype of the SVZa progenitor cells prior to their transplantation, we characterized them in vitro using cell type-specific markers. After 1 day in culture nearly all the SVZa cells were stained with TuJ1, a neuron-specific marker; only an occasional cell exhibited a glial phenotype as judged by the presence of GFAP-immunoreactivity. This indicates that SVZa cells express a neuronal phenotype. To reveal the spatiotemporal distribution of homotopically transplanted neonatal SVZa cells in a host brain, dissociated SVZa cells from Postnatal Day 0 (P0)-P2 animals were labeled with the lipophilic dye PKH26 or the cell proliferation marker BrdU and implanted into the SVZa of host animals of the same age. Within the first week after transplantation there were vast numbers of labeled cells throughout the pathway. Over the next 2 weeks the labeled cells migrated into the overlying cellular layer of the olfactory bulb and began to differentiate, and within 4 weeks the transplanted cells had reached their final positions in the granule cell and glomerular layers of the olfactory bulb in the same proportions as for unmanipulated SVZa-derived cells. While en route to the olfactory bulb the homotopically transplanted cells never strayed from the migratory pathway. In contrast, heterotopically transplanted VZ cells from the embryonic telencephalon did not undergo migration although they did differentiate. These results demonstrate that the homotopically transplanted SVZa-derived cells adopt a mode of migration indistinguishable from that ordinarily utilized by SVZa-derived neurons and that the VZ cells are unable to decipher the same set of guidance cues.

Animals↗
PubMed1995

Phenotypic analysis of migrant, efferent lymphocytes after implantation of cold preserved, peripheral nerve allografts.

Cold-preservation of peripheral nerve allografts in vitro (3 weeks, 5 degrees C) was performed to determine its effect on local lymphocyte migration patterns in vivo. Lymphocyte migration was assessed by continuously monitoring the cell output in the regional lymph for nearly 1 month. Cold-preservation delayed or prevented the typical biphasic increase in efferent lymphocyte output observed after fresh allograft implantation. It also decreased the output of activated lymphocytes (CD 5 and MHC class II positive) compared with that seen in the fresh allograft response. These changes suggest that the host immune response to preserved nerve allografts is altered over a prolonged period in vivo (3 weeks). Cold-preservation may be a useful method of reducing allograft immunogenicity, thereby limiting systemic immunosuppression requirements for the successful clinical utilization of peripheral nerve allografts.

Animals↗
PubMed1995

In search of counterurbanisation: some evidence from Devon on the relationship between patterns of migration and motivation.

"The term counterurbanisation is frequently used to describe the redistribution of a population away from major cities and metropolitan areas and towards more rural areas. The widespread nature of this phenomenon has attracted much attention, yet the concept remains relatively under-developed, and even the basic definition lacks rigour. It is not surprising, therefore, that there has been a lack of cumulative evidence as to the extent of the process and little agreement as to its significance. In essence, ambiguity surrounds the types of movement that should be admitted, the necessary motives for movement and the appropriate measures for both. This paper offers some preliminary suggestions for a more structured approach to the problem. It draws on original survey data from Devon [England], a county which has experienced substantial net in-migration, both to examine the contribution of three alternative definitions of counterurbanisation and to consider how these issues relate to motivation."

Behavior↗
PubMed2005

Hematology patterns of migrating European eels and the role of EVEX virus.

We show that European eels infected with the rhabdovirus EVEX (Eel Virus European X) virus, developed hemorrhage and anemia during simulated migration in large swim tunnels, and died after 1000-1500 km. In contrast, virus-negative animals swam 5500 km, the estimated distance to the spawning ground of the European eel in the Sargasso Sea. Virus-positive eels showed a decline in hematocrit, which was related to the swim distance. Virus-negative eels showed a slightly increased hematocrit. Observed changes in plasma lactate dehydrogenase (LDH), total protein and aspartate aminotransferase (AAT) are indicative of a serious viral infection. Based on these observations, we conclude that eel virus infections may adversely affect the spawning migration of eels, and could be a contributing factor to the worldwide decline of eel.

Animal Migration↗
PubMed2005

Interprovincial migration of physicians in Canada: What are the determinants?

This paper analyzes factors contributing to interprovincial migration of physicians in Canada. It (1) compares the migration patterns of the general practitioners and specialists (medical and surgical); (2) analyzes the changing patterns of out-migration over time via the interactions between the province of residence and time period; (3) analyzes the effect of language as a determinant of migration out of predominantly French speaking Quebec. A logistic formulation of discrete-time hazard model was employed to estimate the probability of moving from the current province of residence. Sets of physician's individual characteristics variables along with dummy variables to reflect the provincial characteristics and various time-periods were included in the model. The model was extended to allow for interaction effects between the province of residence and time-period, and also between language and Quebec (the only province in Canada which is predominantly French speaking) as province of residence. The results suggest that physician's age, specialty, province of residence have significant impact on interprovincial migration of physicians. The probability of moving differs significantly across province of residences in various time-periods.

Adult↗
PubMed2003

Development of genetic differentiation and postzygotic isolation in experimental metapopulations of spider mites.

We studied the development of genetic differentiation and postzygotic isolation in experimental metapopulations of the two-spotted spider mite, Tetranychus urticae Koch. A genetically diverse starter population was made by allowing six inbred sublines to interbreed. Then three migration patterns were tested: no migration, or one or three immigrants per subpopulation per generation. Variations in four traits were investigated: allozymes, acaricide resistance, diapause, and hatchability. In the allozymes, acaricide resistance, and diapause, genetic variation among subpopulations became high in metapopulations with no migration, but not in the others, which showed that one immigrant is enough to prevent genetic differentiation. Hatchability, which was decreased by interbreeding among the six sublines, gradually recovered in succeeding generations. In metapopulations with no migration, hatchability was reduced again after in-migration at the 15th generation. Different karyotypes or coadapted gene complexes can survive in different subpopulations by genetic drift, and both Wolbachia-infected and -noninfected subpopulations may be selected, which would lead to postzygotic isolation between isolated subpopulations. Our results indicate that sampling effects such as genetic drift or stochastic loss of Wolbachia produce postzygotic isolation in laboratory populations of spider mite.

Animals↗
PubMed2004

Systemic treatment with either cyclosporin A or methotrexate does not influence the T helper 1/T helper 2 balance in psoriatic patients.

Cyclosporin A and methotrexate are highly effective drugs in the treatment of psoriasis. It was hypothesized that these therapies might modulate T helper cell cytokine secretion patterns or T cell migration patterns. Flow cytometric determination of interferon-gamma (IFNgamma) and interleukin 4 (IL4) producing T helper cell frequencies, as well as of cutaneous lymphocyte associated antigen (CLA) expressing T cell frequencies was performed in patients suffering from severe psoriasis, before, during, and after a scheduled immunosuppressive regimen with either cyclosporin A or methotrexate. Both cyclosporin A and methotrexate treatment reduced the psoriasis area severity index score after 12 weeks of treatment. Cyclosporin A treatment reduced the frequencies of IL4-producing CD4(pos) T cells, without significantly affecting the T helper 1 to T helper 2 (Th1/Th2) balance but in conjunction with the decreasing number of peripheral blood eosinophil counts. In methotrexate-treated patients, the Th1/Th2 balance was unaffected. Cessation of both therapies resulted in increased numbers of IFNgamma- as well as IL4-producing CD4(pos) T cells as compared to before initiation of oral therapy. Methotrexate, but not cyclosporin A, treatment reduced the frequencies of circulating skin-homing CLA(pos) T cells. This effect was reversed by 4 weeks after withdrawal of methotrexate therapy. We conclude that (1) neither cyclosporin A nor methotrexate affects the balance between Th1 and Th2 cells; (2) exaggerated cytokine production by T helper cells after cessation of oral cyclosporin A or methotrexate drug treatment may contribute to the reappearance of psoriatic skin lesions; and (3) decrease of circulating skin-homing T cells may be responsible for part of the therapeutic effect of methotrexate in severe psoriasis.

Adult↗
PubMed1996

Altered patterns of migration of cytokine-producing T lymphocytes in skin-grafted naive or immune mice following in vivo administration of anti-VCAM-1 or -ICAM-1.

Naive or preimmunized (to B10.BR or BALB.k) C3H/HeJ mice received skin grafts from multiple minor histoincompatible B10.BR or BALB.k mice following antigen-specific portal venous (p.v.) pretransplant transfusion, a protocol known to produce prolongation of graft survival in naive animals. In addition, groups of mice received intravenous (i.v.) infusion following transplantation with a mixture of monoclonal antibodies (mAb) to vascular adhesion molecule-1L: very late activation antigen-4 (VCAM-1:VLA-4) or intracellular adhesion molecule-1:lymphocyte function-associated antigen-3 (ICAM-1:LFA-1). Cells were harvested from different tissues of the grafted mice at various times post grafting. RNA was extracted and analysed, using polymerase chain reaction, for expression of different cytokines potentially involved in the regulation of graft rejection [interleukin-2 (IL-2), IL-4, IL-6, IL-10, tumour necrosis factor-alpha, interferon-gamma and transforming growth factor-beta]. In addition, using limiting dilution analysis, we investigated the frequency of allo-specific and third-party reactive cells producing IL-2 and IL-4 in vitro in different tissues of grafted mice following these treatments. The mAb treatment protocol which produced optimum increases in graft survival in naive versus immune mice was different, with anti-LFA-1:ICAM-1 superior for naive mice compared with anti-VLA-4:VCAM-1, and vice versa for immune animals. However, in each case, increased survival was associated with increases local to the graft in the frequency of occurrence of antigen-specific type-2 cytokine-producing cells.

Animals↗
PubMed1988

Changing patterns of migration and regional economic growth in the U.S.: a demographic perspective.

During the 1970s and early 1980s, the South and West census regions accounted for over 90% of incremental national population, which was easily the highest percentage accounted for by these regions in the nation's history. This paper stresses the importance of powerful demographic forces that contributed to the regional shift, but it does not ignore important economic factors. A major theme of the paper is that because the baby boom has now largely matured out of the most mobile age classes, population and employment growth differentials that strongly favored the South and West will moderate in the future.

Age Factors↗
PubMed1988

Changing patterns of migration in the Adriatic region.

International migration in the Adriatic countries of Albania, Greece, Italy, San Marino, and Yugoslavia is briefly examined using data from official and other published sources. The main types of migratory movements identified by the author within the region are "1) economically motivated migration (legal and clandestine); 2) immigration of refugees for resettlement; 3) immigration with the scope of final resettlement in a third country (transit movements); [and] 4) return migration by former emigrants."

Albania↗